**Transradial Approach for Coronary Interventions: The New Gold Standard for Vascular Access?**

Antoine Guédès *CHU Mont-Godinne, University of Louvain Belgium* 

### **1. Introduction**

The perfect cardiac catheterization technique, including good diagnostic and therapeutic qualities, without risk and with no recovery time for the patient, does not exist. Obtaining initial access to the arterial circulation is the first and most frequent catheterization difficulty encountered by the interventional cardiologist during the procedure. Often, it is also the only difficult part of the exam for the patient because it may cause a vagal reaction or painful spasm. These procedural problems inevitably increase catheterization time and are sometimes the underlying causes of more significant complications. Arterial access is a crucial step of percutaneous cardiac procedures and therefore requires special attention.

Today, percutaneous coronary intervention (PCI) are usually performed via the femoral or radial arteries (a brachial approach may occasionally be required as third choice vascular access). Since the first demonstration of transradial approach feasibility in 1989, by Lucien Campeau, many studies have confirmed this initial experience and especially its safety and performances compared to transfemoral route. Nevertheless, a recent study reports that less than 2% of percutaneous coronary interventions were performed by a transradial approach in the United States between 2004 and 2007(1). The persistent discrepancy between current practice in vascular access site choice and known advantages of a radial access needs to be clarified, enlightened by recent data.

#### **2. Short overview of complications related to arterial access site choice for PCI**

Over the last three decades, advances in percutaneous coronary interventions techniques and contemporary pharmacotherapy have made these procedures safer and more reliable in a wide range of patients, often older and sicker than before.

#### **2.1 Bleeding after percutaneous coronary interventions**

In routine clinical practice, bleeding complications are a frequent non-cardiac outcome of therapy for acute coronary syndromes even in the case of an adequate arterial puncture technique. Aggressive antithrombotic regimens used in this setting even if highly powerful

Transradial Approach

at the end of the procedure.

thrombosis are observed.

**2.2.1 Pseudonaneurysm** 

for Coronary Interventions: The New Gold Standard for Vascular Access? 3

The main difficulty encountered when comparing trials which study the true incidence of haemorrhagic events linked to vascular access options remains the lack of a precise definition for this complication (18-20) or at least of a consensus taking into account main parameters in order to establish a bleeding severity score (clear identification of bleeding site, haematocrit /haemoglobin drop, hemodynamic consequences, treatments required…). Even if some authors (21) report a significant reduction in the incidence of major femoral bleeding complications over time (from 8.4 % in 1995 to 3.5 % in 2005), the single effective way to reduce majors bleeding related to a coronary angiography or intervention procedure, according to recent data, is to use radial access (2,11,22-24). In experts hands, this strategy allows a 50 to 75 % reduction in major bleeding events (24) with the greatest absolute benefit for obese patients and in the setting of acute myocardial infarction (primary or rescue coronary angioplasty). Therefore, radial access should be promoted as the preferential access site for percutaneous coronary interventions. Nevertheless the keys to preventing bleeding complications are well known: good knowledge and recognition of predisposing factors, meticulous examination of the access site before the puncture follow by a careful sheath placement in the artery without forceful manoeuvre and discontinuation of heparin

Other significant access site related complications encountered after a catheterization procedure are pseudoaneurysm, arterio-venous fistula, femoral laceration, femoral thrombosis with or without distal embolization, and any need for a surgical exploration or repair. Less frequently groin infection (puncture site abscess), neural damage and venous

A pseudoaneurysm is defined as an encapsulated hematoma or cavity (contained by surrounding tissues) communicating with the lumen of an artery because of a localized disruption of the media (Fig. 2). It mainly occurs after an inadequate artery compression

**2.2 Other frequent complications related to arterial access site** 

Fig. 1. Large right groin and forearm hematomas.

in reducing ischemic events, also expose patients to a higher rate of bleeding (related or not to the vascular access site).

More than two thirds of all bleeding complications involve the arterial access site and range from a local non significant hematoma to life-threatening bleeding (Fig. 1). The most common origins of bleedings not related to arterial access are gastrointestinal followed by cardiac tamponade and intracranial haemorrhage (2,3).

Retroperitoneal haemorrhage is more difficult to classify because of its double potential aetiology (often linked to manipulations related to a femoral approach but rarely occurring spontaneously in the case of anticoagulation and/or antiplatelet therapy). Retroperitoneal bleeding leading to a major bleed is reported to occur in approximately 0.1% to 0.3% of patient treated by a femoral access but is maybe an underestimate (2,4).

Risk factors for such complications are now well identified and could be divided in four categories (see Table 1).


Table 1. Factors associated with a higher bleeding risk (5-10)

Large randomized trials and registries with "real world" populations of patients have clearly identified clinical characteristics conferring a higher risk of bleeding: advanced age, female gender, obesity, low body weight, chronic renal disease, peripheral vascular disease and a previous history of bleeding. Procedural predictors for an increased bleeding risk include faulty puncture technique, sheath size, prolonged sheath time, use of glycoprotein (GP) IIb/IIIa inhibitors, vascular closure devices, intensity/duration of anticoagulation with heparin, but also vascular access strategy using femoral rather than radial artery(3,9,11-17).

in reducing ischemic events, also expose patients to a higher rate of bleeding (related or not

More than two thirds of all bleeding complications involve the arterial access site and range from a local non significant hematoma to life-threatening bleeding (Fig. 1). The most common origins of bleedings not related to arterial access are gastrointestinal followed by

Retroperitoneal haemorrhage is more difficult to classify because of its double potential aetiology (often linked to manipulations related to a femoral approach but rarely occurring spontaneously in the case of anticoagulation and/or antiplatelet therapy). Retroperitoneal bleeding leading to a major bleed is reported to occur in approximately 0.1% to 0.3% of

Risk factors for such complications are now well identified and could be divided in four








Large randomized trials and registries with "real world" populations of patients have clearly identified clinical characteristics conferring a higher risk of bleeding: advanced age, female gender, obesity, low body weight, chronic renal disease, peripheral vascular disease and a previous history of bleeding. Procedural predictors for an increased bleeding risk include faulty puncture technique, sheath size, prolonged sheath time, use of glycoprotein (GP) IIb/IIIa inhibitors, vascular closure devices, intensity/duration of anticoagulation with heparin, but also vascular access strategy using femoral rather than radial artery(3,9,11-17).





to the vascular access site).

categories (see Table 1).

cardiac tamponade and intracranial haemorrhage (2,3).

**Clinical Factors** - Advanced age

**Biochemical Factors** - Renal insufficiency

Table 1. Factors associated with a higher bleeding risk (5-10)

patient treated by a femoral access but is maybe an underestimate (2,4).

The main difficulty encountered when comparing trials which study the true incidence of haemorrhagic events linked to vascular access options remains the lack of a precise definition for this complication (18-20) or at least of a consensus taking into account main parameters in order to establish a bleeding severity score (clear identification of bleeding site, haematocrit /haemoglobin drop, hemodynamic consequences, treatments required…).

Even if some authors (21) report a significant reduction in the incidence of major femoral bleeding complications over time (from 8.4 % in 1995 to 3.5 % in 2005), the single effective way to reduce majors bleeding related to a coronary angiography or intervention procedure, according to recent data, is to use radial access (2,11,22-24). In experts hands, this strategy allows a 50 to 75 % reduction in major bleeding events (24) with the greatest absolute benefit for obese patients and in the setting of acute myocardial infarction (primary or rescue coronary angioplasty). Therefore, radial access should be promoted as the preferential access site for percutaneous coronary interventions. Nevertheless the keys to preventing bleeding complications are well known: good knowledge and recognition of predisposing factors, meticulous examination of the access site before the puncture follow by a careful sheath placement in the artery without forceful manoeuvre and discontinuation of heparin at the end of the procedure.

Fig. 1. Large right groin and forearm hematomas.

#### **2.2 Other frequent complications related to arterial access site**

Other significant access site related complications encountered after a catheterization procedure are pseudoaneurysm, arterio-venous fistula, femoral laceration, femoral thrombosis with or without distal embolization, and any need for a surgical exploration or repair. Less frequently groin infection (puncture site abscess), neural damage and venous thrombosis are observed.

#### **2.2.1 Pseudonaneurysm**

A pseudoaneurysm is defined as an encapsulated hematoma or cavity (contained by surrounding tissues) communicating with the lumen of an artery because of a localized disruption of the media (Fig. 2). It mainly occurs after an inadequate artery compression

Transradial Approach

interventions (2,4).

in the chapter.

(26,35).

**2.2.4 Arterial thrombosis** 

for Coronary Interventions: The New Gold Standard for Vascular Access? 5

Due to the increasing number of percutaneous cardiac procedures performed annually and to the worldwide operator preference for this vascular access, most arterial thromboses occur in the common femoral artery. Nevertheless the incidence of this serious adverse event remains very low after coronary intervention (<0.5%) probably because of the widespread use of high dose multi-drug antithrombotic therapy for percutaneous

The common femoral artery being the unique blood supply to the leg, an urgent diagnostic of this complication followed by immediate heparinization and mechanical or surgical thrombectomy are usually required. On the contrary, radial artery thrombosis is a relatively frequent asymptomatic condition (incidence: 3-6 %). It is a benign issue, with nearly no clinical sequelae observed after occlusion of this vessel, because of the double blood supply to the hand insured by the palmar arch. Many of these radial occlusions (40-60%) are spontaneously recanalized after one month (11,34). This specific point will be discussed later

**2.3 Impact of vascular closure devices on vascular access site complications** 

(up to 3.7% versus less than 0.7%, respectively) (37-40).

experience with these devices over time (4,42,44).

Today, closure devices are widely used to obtain a rapid hemostasis after percutaneous transfemoral approach but their safety remains largely controversial. Marginal evidences concerning the effectiveness of these devices are derived from pooled analyses of a heterogeneous group of small randomized trials, many of poor methodological quality

All of the approved arterial closure devices have proven their efficacy in obtaining immediate hemostasis after sheath removal, in allowing early ambulation, and in improving patient comfort (36). However, there is no report showing a clear reduction of access site complications related to their use (compared to efficacy of manual compression) especially after diagnostic angiography. In the setting of percutaneous coronary interventions, metaanalysis of randomized trials only showed a trend towards less access site related complications with some of these devices but also an increased risk with others (26,35). Additionally, four separate prospective studies have found that bleeding complications were more frequent with transfemoral access and closure device than with transradial access

There are still matters of concern about the use of these devices. For example they may increase the risk of hematoma and pseudoaneurysm formation (26,35,36,41-43). Moreover, early device failure rates and their impact on vascular access site complications are not always clearly reported in these trials but may decrease after the initial learning curve. Recently, data with the last generation of vascular closure devices suggest that their use may decrease vascular complications but these points had to be confirmed once again by large randomized trials because it maybe simply reflects a better patient selection and operator

When an arteriotomy closure device is used, some specific complications may occur in addition to those previously described for manual compression. A higher rate of access site infections (0.3% versus 0.05 % with manual compression) and more episodes of acute or late

following sheath withdrawal. Predisposing factors for this iatrogenic arterial trauma are impaired hemostasis and factors known to be associated with difficult and prolonged procedures (peripheral vascular disease, large sheath use, aggressive anticoagulation and/or fibrinolytic therapy, prolonged sheath and anticoagulation times) and in case of a femoral approach the concomitant use of an intra aortic balloon pump and an early ambulation after catheterization. The reported incidence for femoral access seems to be around 1% (maybe higher), and is lower in the case of radial access (≤ 0.2 %) (2,25-28).

An adequate recognition of this complication, which may occur more than one year after the catheterization procedure, is mandatory because of the risk of rupture estimated at approximately 4 % for large pseudoaneurysms (> 3cm) (29-31).

Fig. 2. Pseudoaneurysm of the radial artery (2D color-Doppler flow imaging)

#### **2.2.2 Arteriovenous fistula**

An arteriovenous fistula results from an overlying vein puncture during femoral artery catheterization, creating a communication between the two vessels after sheath removal. A high velocity and continuous jet originating from the artery and going into the vein lumen, is often easily demonstrated by color flow Doppler examination if clinical manifestations exist at the access site. The reported incidence is low in recent trials studying patients after a coronary angiography or intervention by femoral approach (0.1-2.2%) and extremely rare for radial approach (< 0.1%) (2,4,26).

By femoral approach, the occurrence of arteriovenous fistula and pseudonaneurysm is reported to be significantly higher if the puncture site is located distal to the division of the deep and superficial femoral arteries (25).

#### **2.2.3 Arterial wall dissection**

Arterial wall dissection is probably frequently unrecognized especially in cases of local dissection although its true incidence is hard to establish. Regarding published and already historical data for recognized dissection, the incidence of this arterial wall injury varies from 0.01% to 0.5% (32,33). However, when considering the fact that, as demonstrated by angiographic studies, 25% of patients admitted for a catheterization procedure had common femoral artery atherosclerotic plaques determining at least a 20 % stenosis, it is easy to understand that all intravascular foreign body as a needle or catheter may easily deflect off some of these plaques.

#### **2.2.4 Arterial thrombosis**

4 Coronary Interventions

following sheath withdrawal. Predisposing factors for this iatrogenic arterial trauma are impaired hemostasis and factors known to be associated with difficult and prolonged procedures (peripheral vascular disease, large sheath use, aggressive anticoagulation and/or fibrinolytic therapy, prolonged sheath and anticoagulation times) and in case of a femoral approach the concomitant use of an intra aortic balloon pump and an early ambulation after catheterization. The reported incidence for femoral access seems to be around 1% (maybe higher), and is lower in the case of radial access (≤ 0.2 %) (2,25-28).

An adequate recognition of this complication, which may occur more than one year after the catheterization procedure, is mandatory because of the risk of rupture estimated at

approximately 4 % for large pseudoaneurysms (> 3cm) (29-31).

**2.2.2 Arteriovenous fistula** 

radial approach (< 0.1%) (2,4,26).

**2.2.3 Arterial wall dissection** 

some of these plaques.

deep and superficial femoral arteries (25).

Fig. 2. Pseudoaneurysm of the radial artery (2D color-Doppler flow imaging)

An arteriovenous fistula results from an overlying vein puncture during femoral artery catheterization, creating a communication between the two vessels after sheath removal. A high velocity and continuous jet originating from the artery and going into the vein lumen, is often easily demonstrated by color flow Doppler examination if clinical manifestations exist at the access site. The reported incidence is low in recent trials studying patients after a coronary angiography or intervention by femoral approach (0.1-2.2%) and extremely rare for

By femoral approach, the occurrence of arteriovenous fistula and pseudonaneurysm is reported to be significantly higher if the puncture site is located distal to the division of the

Arterial wall dissection is probably frequently unrecognized especially in cases of local dissection although its true incidence is hard to establish. Regarding published and already historical data for recognized dissection, the incidence of this arterial wall injury varies from 0.01% to 0.5% (32,33). However, when considering the fact that, as demonstrated by angiographic studies, 25% of patients admitted for a catheterization procedure had common femoral artery atherosclerotic plaques determining at least a 20 % stenosis, it is easy to understand that all intravascular foreign body as a needle or catheter may easily deflect off Due to the increasing number of percutaneous cardiac procedures performed annually and to the worldwide operator preference for this vascular access, most arterial thromboses occur in the common femoral artery. Nevertheless the incidence of this serious adverse event remains very low after coronary intervention (<0.5%) probably because of the widespread use of high dose multi-drug antithrombotic therapy for percutaneous interventions (2,4).

The common femoral artery being the unique blood supply to the leg, an urgent diagnostic of this complication followed by immediate heparinization and mechanical or surgical thrombectomy are usually required. On the contrary, radial artery thrombosis is a relatively frequent asymptomatic condition (incidence: 3-6 %). It is a benign issue, with nearly no clinical sequelae observed after occlusion of this vessel, because of the double blood supply to the hand insured by the palmar arch. Many of these radial occlusions (40-60%) are spontaneously recanalized after one month (11,34). This specific point will be discussed later in the chapter.

#### **2.3 Impact of vascular closure devices on vascular access site complications**

Today, closure devices are widely used to obtain a rapid hemostasis after percutaneous transfemoral approach but their safety remains largely controversial. Marginal evidences concerning the effectiveness of these devices are derived from pooled analyses of a heterogeneous group of small randomized trials, many of poor methodological quality (26,35).

All of the approved arterial closure devices have proven their efficacy in obtaining immediate hemostasis after sheath removal, in allowing early ambulation, and in improving patient comfort (36). However, there is no report showing a clear reduction of access site complications related to their use (compared to efficacy of manual compression) especially after diagnostic angiography. In the setting of percutaneous coronary interventions, metaanalysis of randomized trials only showed a trend towards less access site related complications with some of these devices but also an increased risk with others (26,35). Additionally, four separate prospective studies have found that bleeding complications were more frequent with transfemoral access and closure device than with transradial access (up to 3.7% versus less than 0.7%, respectively) (37-40).

There are still matters of concern about the use of these devices. For example they may increase the risk of hematoma and pseudoaneurysm formation (26,35,36,41-43). Moreover, early device failure rates and their impact on vascular access site complications are not always clearly reported in these trials but may decrease after the initial learning curve. Recently, data with the last generation of vascular closure devices suggest that their use may decrease vascular complications but these points had to be confirmed once again by large randomized trials because it maybe simply reflects a better patient selection and operator experience with these devices over time (4,42,44).

When an arteriotomy closure device is used, some specific complications may occur in addition to those previously described for manual compression. A higher rate of access site infections (0.3% versus 0.05 % with manual compression) and more episodes of acute or late

Transradial Approach

CFA is relatively deep.

patients.

artery

• The ideal site of puncture may be hard to identify especially in obese patients.

• The inguinal crease is an unreliable landmark in more than two thirds of

• The strongest femoral pulse correctly identified the mid-CFA in 90 % of cases

• The most reliable landmark is probably the junction between the middle and the

CFA lies just near a major vein (Femoral

Table 2. Comparison of access site characteristics (46-48)

the Modified Allen's Test (49) or alternative tests, has been assessed.

**3.2 Learning curve and prerequisite conditions for a safe technique conversion** 

The same catheterization laboratory set up and patient preparation as for femoral procedures can be used for the radial approach and only minor adaptations to improve patient and operator comfort, especially for the puncture, are required. A good arm support system is the only inescapable element needed and a pulse oximeter (finger plethysmography) may be required to perform alternative tests in case of an abnormal

Transradial access is known to be technically more demanding and time consuming,

lower third of the femoral head (radiographic landmark)

Compression of the CFA may be hard • No hard and fixed structures behind the

Vein) and nerve (Femoral Nerve)

modified Allen's test (50,51).

especially during the early learning curve (52).

Puncture site is over the hip joint

for Coronary Interventions: The New Gold Standard for Vascular Access? 7

Distal RA had a superficial course, • This artery is easy to palpate even in

Puncture site is not over a joint

RA can easily be compressed with

just beneath the artery

• At the puncture site, radial bone is

RA is separated from median nerve and

minimal pressure

by the palmar arch

major veins

CFA is the unique blood supply to the leg Double blood supply to the hand insured

Its superficial course makes this artery easily accessible to puncture and, after the procedure, more amenable to compression (because of bone support beneath), even in obese patients. The puncture site is not over a joint, so compression devices are always stable and effective to ensure good hemostasis after sheath removal. Also wrist movements are not impaired after a transradial percutaneous intervention, which facilitates rapid recovery and makes an outpatient strategy feasible. Moreover, the radial artery is separated from median nerve and major veins of the forearm making post-catheter injuries of these structures rare. Lastly, the double blood supply to the hand makes hand ischemia an almost impossible complication if the presence of functional collaterals between the radial and the ulnar arteries, as judged by

• At the level of the puncture site, the artery lies just under skin and fascias

• The most reliable landmark is ideally 2-3 cm proximal to the flexor crease of the wrist (clinical landmark)

obese patients

**Common Femoral Artery (CFA) Radial Artery (RA)** 

limb ischemia (0.4% versus 0.1% for manual compression) are reported. The need for surgery, in case of device failure, is not commonly reported with details in the great majority of previous published trials. Nevertheless, surgery for partial embolization, to remove trapped components of these devices or after vessel laceration is uncommon(4,35).

Given the remaining uncertainty about their true impact on vascular complications and the difficulty to assess costs induced by specific vascular access complications, the widespread adoption of these devices following endovascular interventions is still controversial and needs to be clarified in the future (4,45).

#### **2.4 Conclusions**

All vascular access techniques, even if perfectly handled by the interventional cardiologist are linked with a minimal but inevitable rate of complications arising because materials enter atherosclerotic vessels. To avoid more serious clinical consequences for the patients, it is particularly important to give meticulous attention to the access site not only before the puncture but also in the hours following the procedure and to recognize predisposing factors for such complications.

#### **3. Anatomical considerations and technical aspects of a transradial approach**

#### **3.1 Favorable anatomical characteristics of the radial artery**

Differences observed in terms of vascular complications after radial and femoral percutaneous interventions are mainly based on favorable anatomical characteristics of the radial artery (compared to those describe for the common femoral artery) (Table 2 and Fig. 3).

Fig. 3. Landmarks for vascular access (48,50,51)

limb ischemia (0.4% versus 0.1% for manual compression) are reported. The need for surgery, in case of device failure, is not commonly reported with details in the great majority of previous published trials. Nevertheless, surgery for partial embolization, to remove trapped components of these devices or after vessel laceration is uncommon(4,35). Given the remaining uncertainty about their true impact on vascular complications and the difficulty to assess costs induced by specific vascular access complications, the widespread adoption of these devices following endovascular interventions is still controversial and

All vascular access techniques, even if perfectly handled by the interventional cardiologist are linked with a minimal but inevitable rate of complications arising because materials enter atherosclerotic vessels. To avoid more serious clinical consequences for the patients, it is particularly important to give meticulous attention to the access site not only before the puncture but also in the hours following the procedure and to recognize predisposing

**3. Anatomical considerations and technical aspects of a transradial approach** 

Differences observed in terms of vascular complications after radial and femoral percutaneous interventions are mainly based on favorable anatomical characteristics of the radial artery (compared to those describe for the common femoral artery) (Table 2 and

**3.1 Favorable anatomical characteristics of the radial artery** 

Fig. 3. Landmarks for vascular access (48,50,51)

needs to be clarified in the future (4,45).

factors for such complications.

**2.4 Conclusions** 

Fig. 3).


Table 2. Comparison of access site characteristics (46-48)

Its superficial course makes this artery easily accessible to puncture and, after the procedure, more amenable to compression (because of bone support beneath), even in obese patients. The puncture site is not over a joint, so compression devices are always stable and effective to ensure good hemostasis after sheath removal. Also wrist movements are not impaired after a transradial percutaneous intervention, which facilitates rapid recovery and makes an outpatient strategy feasible. Moreover, the radial artery is separated from median nerve and major veins of the forearm making post-catheter injuries of these structures rare. Lastly, the double blood supply to the hand makes hand ischemia an almost impossible complication if the presence of functional collaterals between the radial and the ulnar arteries, as judged by the Modified Allen's Test (49) or alternative tests, has been assessed.

#### **3.2 Learning curve and prerequisite conditions for a safe technique conversion**

The same catheterization laboratory set up and patient preparation as for femoral procedures can be used for the radial approach and only minor adaptations to improve patient and operator comfort, especially for the puncture, are required. A good arm support system is the only inescapable element needed and a pulse oximeter (finger plethysmography) may be required to perform alternative tests in case of an abnormal modified Allen's test (50,51).

Transradial access is known to be technically more demanding and time consuming, especially during the early learning curve (52).

Transradial Approach

spasm (56).

time and contrast volumes used for the procedures.

in order to prevent vascular injury and perforation.

**3.3 Difficult cases by transradial approach and limits of the technique** 

for Coronary Interventions: The New Gold Standard for Vascular Access? 9

demonstrates the equivalence of the two techniques in terms of complications at the level of the coronary tree (2). The number of guiding catheters required for the procedure, the rate of abrupt coronary closure, no reflow, dissection with reduced flow, perforation, catheter thrombus and stent thrombosis were similar in the two arms of the study. These observations had already emerged from the meta-analysis performed by Agostoni in 2004 (11), which did not show statistically significant differences in terms of procedural failure for studies performed after 1999. Similarly, no differences were shown in PCI procedural

Transradial approach is considered to be a difficult approach, first because of the puncture task but also for the frequent occurrence of spasm, difficult catheter selection or inability to

Spasm is usually related to prolonged or excessive catheter manipulation but may already occur during puncture or after sheath insertion. By using adequate doses of spasmolytic drugs (intra-arterial verapamil) at the beginning and during the procedure and small catheter size (5 French), refractory spasm becomes rare (1,1% versus 4,8% with 6 French catheters) (54). Interestingly, spasm more frequently occurs where difficulties are encountered in advancing the wire or the catheter and not only at the level of the radial artery (it can also be seen at the level of the upper limb or of the brachio-cephalic trunk). For experienced radial operators, spasm is not reported as a pertinent cause of radial approach failure during percutaneous coronary interventions (11,53). However, when resistance occurs, it is strongly recommended to perform an angiogram to adequately define the anatomy, spasm level or rarely stenosis or occlusion levels. Several studies have shown that intra-arterial verapamil and nitroglycerine are the most effective medications to prevent or to relieve spasms. Moreover, selective angiograms of the left and right coronary arteries (as well as left ventriculography) are possible with only one catheter by transradial approach (Optitorque TIG™ catheter, Terumo corp.). Thus, there should not be a need for three different catheter exchanges, which also helps in reducing the occurrence of spasm. In the same way, sheath-induced spasms are minimized and far less frequent when hydrophilic-coated materials are used. Hydrophilic coating also helps to reduce patient discomfort and facilitates sheath withdrawal (55). Finally, a higher incidence of radial artery thrombosis is documented in patients with periprocedural

Beginners frequently evoke loops, tortuosities and anatomic variants as one other major hurdle to overcome during learning curve. These unpredictable abnormalities are quite rare in current practice but the most challenging ones may require an alternative vascular access site. Tips and tricks, state of the art materials (especially hydrophilic wire and 0.014" PTCA guidewires) are helpful in overcoming these difficulties in a large majority of these cases. Solutions that work are often those associated with gentle wire and catheter manipulations

Another frequently advanced argument against transradial intervention is inadequate guiding support. Randomized trials performed after 2000 do not advocate this point when procedural success is compared to those reported for transfemoral PCI studies, especially when dedicated radial materials are used (2,11,37,57). Most radial arteries have a lumen

overcome difficult radial or vascular anatomy, especially during the learning curve.

The small caliber (2-3.5 mm in diameter) and the alpha–adrenergic innervations of the artery make the puncture task the key point of a successful transradial procedure.

When the accurate site of puncture has been correctly identified, the most critical step of the radial catheterization procedure begins. Different puncture techniques exist but the most commonly used today by experienced radial operators is the over-the-needle technique (50,51).

As described in many papers dedicated to transradial approach (53) puncture remains, for beginners, the cornerstone of the learning curve and it takes time to develop all the skills required, even for experienced interventionalists. Obtaining arterial access by a single or a limited number of puncture attempts is probably the best way to avoid difficulties linked to a refractory spasm following a difficult puncture.

This is the reason why, it is strongly recommended to take extra time to prepare and realize the puncture and to keep in mind that gentle and cautious manipulations will always pay off later. Failure of the puncture task (inability to puncture or to wire the artery) accounts for more than 50 % of transradial approach failures. Even if it takes approximately 200-300 cases to overcome initial difficulties, several studies confirms the reality of a long learning curve (53). During the beginner's phase of radial access experience, good patient selection with a readily palpable radial pulse is necessary to help perfect all the skills needed for this elegant technique. Weak radial pulses, small radial arteries, old patients, patients with known peripheral vascular disease or post CABG surgery should be avoided at this time. All these elements, required to identify patients with the most difficult access, are given by the bedside clinical evaluation of the patient, even if puncture is frequently less difficult than anticipated.

During the procedure, inability to cross forearm, arm or intra thoracic vasculature difficulties accounts for 10 % of transradial approach failures, inability to reach a coronary or graft ostia due to difficulties in rotating and manipulating the catheters for 10% and the remaining failures are related to the inability to reach a contra-lateral mammary graft.

An access site crossover, related to failure of initial strategy, is required in 6-7% of transradial procedures compared to less than 2% in case of femoral approach (including PCI procedures). For high volume radial operators or centers, lower crossover rates are reported (4-6%) (2,11,24,53). Once again, these data confirm the importance of experience and expertise when interventionalists are dealing with this approach.

In these conditions, with growing experience and state of the art materials, and if there is a systematic use of the contra-lateral radial artery in case of puncture failure on the initial side (the same technique is applied for femoral access) a very high success rate can be expected by this technique, approximately 98 % or more, with no significant differences among subgroups of patients (53).

After a while, when experience and confidence in the technique has grown, more adequate catheter choice and skills in their manipulations will ensure similar clinical results as in the femoral approach (2,11).

Indeed, PCI success rate is similar for the two approaches. The RIVAL study, the largest randomized trial comparing radial and femoral access for acute coronary syndromes,

The small caliber (2-3.5 mm in diameter) and the alpha–adrenergic innervations of the artery

When the accurate site of puncture has been correctly identified, the most critical step of the radial catheterization procedure begins. Different puncture techniques exist but the most commonly used today by experienced radial operators is the over-the-needle technique

As described in many papers dedicated to transradial approach (53) puncture remains, for beginners, the cornerstone of the learning curve and it takes time to develop all the skills required, even for experienced interventionalists. Obtaining arterial access by a single or a limited number of puncture attempts is probably the best way to avoid difficulties linked to

This is the reason why, it is strongly recommended to take extra time to prepare and realize the puncture and to keep in mind that gentle and cautious manipulations will always pay off later. Failure of the puncture task (inability to puncture or to wire the artery) accounts for more than 50 % of transradial approach failures. Even if it takes approximately 200-300 cases to overcome initial difficulties, several studies confirms the reality of a long learning curve (53). During the beginner's phase of radial access experience, good patient selection with a readily palpable radial pulse is necessary to help perfect all the skills needed for this elegant technique. Weak radial pulses, small radial arteries, old patients, patients with known peripheral vascular disease or post CABG surgery should be avoided at this time. All these elements, required to identify patients with the most difficult access, are given by the bedside clinical evaluation of the patient, even if puncture is frequently less difficult than

During the procedure, inability to cross forearm, arm or intra thoracic vasculature difficulties accounts for 10 % of transradial approach failures, inability to reach a coronary or graft ostia due to difficulties in rotating and manipulating the catheters for 10% and the remaining failures are related to the inability to reach a contra-lateral mammary graft.

An access site crossover, related to failure of initial strategy, is required in 6-7% of transradial procedures compared to less than 2% in case of femoral approach (including PCI procedures). For high volume radial operators or centers, lower crossover rates are reported (4-6%) (2,11,24,53). Once again, these data confirm the importance of experience and

In these conditions, with growing experience and state of the art materials, and if there is a systematic use of the contra-lateral radial artery in case of puncture failure on the initial side (the same technique is applied for femoral access) a very high success rate can be expected by this technique, approximately 98 % or more, with no significant differences among

After a while, when experience and confidence in the technique has grown, more adequate catheter choice and skills in their manipulations will ensure similar clinical results as in the

Indeed, PCI success rate is similar for the two approaches. The RIVAL study, the largest randomized trial comparing radial and femoral access for acute coronary syndromes,

expertise when interventionalists are dealing with this approach.

make the puncture task the key point of a successful transradial procedure.

a refractory spasm following a difficult puncture.

(50,51).

anticipated.

subgroups of patients (53).

femoral approach (2,11).

demonstrates the equivalence of the two techniques in terms of complications at the level of the coronary tree (2). The number of guiding catheters required for the procedure, the rate of abrupt coronary closure, no reflow, dissection with reduced flow, perforation, catheter thrombus and stent thrombosis were similar in the two arms of the study. These observations had already emerged from the meta-analysis performed by Agostoni in 2004 (11), which did not show statistically significant differences in terms of procedural failure for studies performed after 1999. Similarly, no differences were shown in PCI procedural time and contrast volumes used for the procedures.

#### **3.3 Difficult cases by transradial approach and limits of the technique**

Transradial approach is considered to be a difficult approach, first because of the puncture task but also for the frequent occurrence of spasm, difficult catheter selection or inability to overcome difficult radial or vascular anatomy, especially during the learning curve.

Spasm is usually related to prolonged or excessive catheter manipulation but may already occur during puncture or after sheath insertion. By using adequate doses of spasmolytic drugs (intra-arterial verapamil) at the beginning and during the procedure and small catheter size (5 French), refractory spasm becomes rare (1,1% versus 4,8% with 6 French catheters) (54). Interestingly, spasm more frequently occurs where difficulties are encountered in advancing the wire or the catheter and not only at the level of the radial artery (it can also be seen at the level of the upper limb or of the brachio-cephalic trunk). For experienced radial operators, spasm is not reported as a pertinent cause of radial approach failure during percutaneous coronary interventions (11,53). However, when resistance occurs, it is strongly recommended to perform an angiogram to adequately define the anatomy, spasm level or rarely stenosis or occlusion levels. Several studies have shown that intra-arterial verapamil and nitroglycerine are the most effective medications to prevent or to relieve spasms. Moreover, selective angiograms of the left and right coronary arteries (as well as left ventriculography) are possible with only one catheter by transradial approach (Optitorque TIG™ catheter, Terumo corp.). Thus, there should not be a need for three different catheter exchanges, which also helps in reducing the occurrence of spasm. In the same way, sheath-induced spasms are minimized and far less frequent when hydrophilic-coated materials are used. Hydrophilic coating also helps to reduce patient discomfort and facilitates sheath withdrawal (55). Finally, a higher incidence of radial artery thrombosis is documented in patients with periprocedural spasm (56).

Beginners frequently evoke loops, tortuosities and anatomic variants as one other major hurdle to overcome during learning curve. These unpredictable abnormalities are quite rare in current practice but the most challenging ones may require an alternative vascular access site. Tips and tricks, state of the art materials (especially hydrophilic wire and 0.014" PTCA guidewires) are helpful in overcoming these difficulties in a large majority of these cases. Solutions that work are often those associated with gentle wire and catheter manipulations in order to prevent vascular injury and perforation.

Another frequently advanced argument against transradial intervention is inadequate guiding support. Randomized trials performed after 2000 do not advocate this point when procedural success is compared to those reported for transfemoral PCI studies, especially when dedicated radial materials are used (2,11,37,57). Most radial arteries have a lumen

Transradial Approach

**3.4 Conclusions** 

without any delay.

transradial procedure to this day.

9% of patients in other studies.

for Coronary Interventions: The New Gold Standard for Vascular Access? 11

skilled operators (53,67). A successful selective opacification of the contra-lateral mammary artery can be expected in 50% of these particular cases if performed by an experienced operator using dedicated catheters (53).In our institution, we mainly use for this purpose the Outlook™ 4 French diagnostic catheter (Terumo corp.).To reach saphenous vein grafts, either left or right radial approaches can be chosen, with a similar success rate using standard catheter curves (63). Sometimes, a bilateral radial approach, during the same

Finally, there are only a few relative contraindications to a transradial approach: patients with a negative Allen test in both hands, patients with end-stage renal disease (just before the creation of an arteriovenous fistula for haemodialysis) and patients with known severe obstructive atherosclerotic disease at the level of the innominate, subclavian or upper limb arteries. Finally, some patients may have had previous coronary artery bypass surgery using

One challenge encountered with radial access is the steep learning curve, but this hurdle can be more easily overcome by following an educational program dedicated to this approach and addressed to interventionalists and fellows in training. The widespread diffusion of the technique in teaching centers as well as the growing interest of major cardiovascular societies and device industry for this approach will also progressively ensure its greater

Despite a proven safety profile leading to a drastic reduction of vascular access site bleeding, the transradial approach is not totally free of complications. Catheterizers must be aware of some rare complications, which are often minor and localized if recognized

**4.1 Post procedural radial artery thrombosis: The main pitfall of transradial approach?**  Although radial artery thrombosis is still a matter of concern after a transradial approach, this complication is usually benign because of the double blood supply to the hand insured by the two forearm arteries inter-connected at the level of the palmar arch. Moreover, handthreatening ischemia, with necrosis or clinical sequelae, has not been reported after a

As shown by studies that have planned post catheterization Doppler ultrasound examinations, the incidence of radial artery thrombosis ranges, in general, from 3% to 6% but one study reports a rate of 9.5% (34,56,68-71). A loss of radial pulse is reported in up to

The occlusion rate increases with the size of catheters used for the procedure (54,72) and is more precisely related to the ratio between the inner radial artery diameter and the sheath outer diameter (73) . The incidence of occlusion is 4% if the ratio is higher than 1 and rises

procedure, is necessary to obtain adequate images of the grafts.

a radial artery as a conduit which precludes radial access by this side.

penetration in the interventional cardiologists' community.

**4. Specific complications of transradial approach** 

dramatically to 13% in patients with a ratio of less than 1.

large enough to accommodate 6 French catheters and some large radial arteries are able to eventually accept 7 French catheters or larger, but these sizes are not often required.

Large lumen 6 French guiding catheters with dedicated radial shapes give good back up support and allow to perform a wide range of the most complex intracoronary procedures (ostial or bifurcation lesions, left main stenosis, chronic total occlusions, thrombectomy, rotational atherectomy, saphenous vein graft lesions, acute coronary syndromes and STelevation myocardial infarction) (2,58-63) but standard curves designed for femoral approach also work well in most cases.

Nevertheless, in routine clinical practice, 5 French guiding catheters make direct stenting easily feasible in the great majority of procedures. In a randomized comparison study, Dahm had even shown a trend in favor of the superiority of 5 French guiding catheters over 6 French guiding catheters in terms of procedural (95.4 versus 92.9 %, p =0,097) and clinical success (93.1 versus 90.5 %, p=0,097) (54).On the other hand, today, with larger sheathless guiding catheter technology, coronary techniques only accessible by a femoral way are far less numerous than before (64,65). For example, sheathless 7.5 French guiding catheters open the way for the most complex PCI techniques, in nearly all patients, by transradial approach but had smaller outer diameters than 6 French radial introducer sheaths.

As with the femoral approach, the ideal sizing and shape of guiding catheters is still, and will stay a matter for debate.

The side to choose for the first radial approach in a given patient also remains a controversial issue with no clear answer. In most centers, transradial coronary interventions are performed through the right radial artery, because this side offers a more comfortable working position for the operator, but on a technical point of view there is some evidence that catheter manipulation could be easier by a left-sided approach, because of similar sensations compared to a femoral way and perhaps offering more back-up support for guiding catheters. In the TALENT study, a randomized comparison of right versus left radial approach for diagnostic procedures, the left approach was associated with lower fluoroscopy time and radiation dose, reflecting an easier procedure, particularly in older patients (> 70 years) and for operators in training (66). The absence of a radial artery pulse or a negative Modified Allen's Test on one side, as well as the need to selectively cannulate a mammary bypass graft also frequently influence the choice. Today, long catheters allow to easily reach the infradiaphragmatic arterial system (renal, mesenteric, iliac, femoral or lower limb arteries but also for example a gastro-epiploic bypass graft). If these catheters are not available, a left radial approach saves ten centimeters of catheter length (by this route, catheters do not cross the arch of aorta).Similarly, the cerebrovascular pathology (carotid and vertebral arteries) can be imaged and eventually treated by transradial approach.

In routine clinical practice, the control of bypass grafts is also a frequent request. Angiography of the left internal mammary artery is easy to perform by the left radial approach (as for a right internal mammary artery by the right radial approach). In case of a bilateral mammary artery bypass graft, a right radial approach should be preferred but left internal mammary artery opacification by the right radial remains challenging even for skilled operators (53,67). A successful selective opacification of the contra-lateral mammary artery can be expected in 50% of these particular cases if performed by an experienced operator using dedicated catheters (53).In our institution, we mainly use for this purpose the Outlook™ 4 French diagnostic catheter (Terumo corp.).To reach saphenous vein grafts, either left or right radial approaches can be chosen, with a similar success rate using standard catheter curves (63). Sometimes, a bilateral radial approach, during the same procedure, is necessary to obtain adequate images of the grafts.

Finally, there are only a few relative contraindications to a transradial approach: patients with a negative Allen test in both hands, patients with end-stage renal disease (just before the creation of an arteriovenous fistula for haemodialysis) and patients with known severe obstructive atherosclerotic disease at the level of the innominate, subclavian or upper limb arteries. Finally, some patients may have had previous coronary artery bypass surgery using a radial artery as a conduit which precludes radial access by this side.

#### **3.4 Conclusions**

10 Coronary Interventions

large enough to accommodate 6 French catheters and some large radial arteries are able to

Large lumen 6 French guiding catheters with dedicated radial shapes give good back up support and allow to perform a wide range of the most complex intracoronary procedures (ostial or bifurcation lesions, left main stenosis, chronic total occlusions, thrombectomy, rotational atherectomy, saphenous vein graft lesions, acute coronary syndromes and STelevation myocardial infarction) (2,58-63) but standard curves designed for femoral

Nevertheless, in routine clinical practice, 5 French guiding catheters make direct stenting easily feasible in the great majority of procedures. In a randomized comparison study, Dahm had even shown a trend in favor of the superiority of 5 French guiding catheters over 6 French guiding catheters in terms of procedural (95.4 versus 92.9 %, p =0,097) and clinical success (93.1 versus 90.5 %, p=0,097) (54).On the other hand, today, with larger sheathless guiding catheter technology, coronary techniques only accessible by a femoral way are far less numerous than before (64,65). For example, sheathless 7.5 French guiding catheters open the way for the most complex PCI techniques, in nearly all patients, by transradial approach but had smaller outer diameters than 6 French radial introducer

As with the femoral approach, the ideal sizing and shape of guiding catheters is still, and

The side to choose for the first radial approach in a given patient also remains a controversial issue with no clear answer. In most centers, transradial coronary interventions are performed through the right radial artery, because this side offers a more comfortable working position for the operator, but on a technical point of view there is some evidence that catheter manipulation could be easier by a left-sided approach, because of similar sensations compared to a femoral way and perhaps offering more back-up support for guiding catheters. In the TALENT study, a randomized comparison of right versus left radial approach for diagnostic procedures, the left approach was associated with lower fluoroscopy time and radiation dose, reflecting an easier procedure, particularly in older patients (> 70 years) and for operators in training (66). The absence of a radial artery pulse or a negative Modified Allen's Test on one side, as well as the need to selectively cannulate a mammary bypass graft also frequently influence the choice. Today, long catheters allow to easily reach the infradiaphragmatic arterial system (renal, mesenteric, iliac, femoral or lower limb arteries but also for example a gastro-epiploic bypass graft). If these catheters are not available, a left radial approach saves ten centimeters of catheter length (by this route, catheters do not cross the arch of aorta).Similarly, the cerebrovascular pathology (carotid and vertebral arteries) can be imaged and eventually treated by transradial

In routine clinical practice, the control of bypass grafts is also a frequent request. Angiography of the left internal mammary artery is easy to perform by the left radial approach (as for a right internal mammary artery by the right radial approach). In case of a bilateral mammary artery bypass graft, a right radial approach should be preferred but left internal mammary artery opacification by the right radial remains challenging even for

eventually accept 7 French catheters or larger, but these sizes are not often required.

approach also work well in most cases.

sheaths.

approach.

will stay a matter for debate.

One challenge encountered with radial access is the steep learning curve, but this hurdle can be more easily overcome by following an educational program dedicated to this approach and addressed to interventionalists and fellows in training. The widespread diffusion of the technique in teaching centers as well as the growing interest of major cardiovascular societies and device industry for this approach will also progressively ensure its greater penetration in the interventional cardiologists' community.
