**4. Procedure**

#### **4.1. Patient preparation**

General considerations resemble those of the other interventional procedures. Fasting is needed for at least 8 hours for solid foods and 3 hours for liquids. The patient should be hydrated according to the standard protocols for the prevention of contrast-induced acute kidney injury. BMV and even transseptal catheterization can be performed with no or minimal contrast media; accordingly, contrast-induced nephropathy is not a major issue. Rapid heart rate in patients with AF might interfere in stable balloon dilatation and should be controlled. No specific pharmacologic pretreatment is needed before BMV, but most medications (betablockers, calcium channel blockers, digoxin, etc.) are routinely continued. Warfarin should be withheld for 3 days before the procedure. Instead, heparin is needed to be infused while the patient is under therapeutic INR levels (INR < 2). Heparin infusion is stopped 4 hours before the patient arrives at the catheterization laboratory. Preprocedural TEE is of paramount importance to exclude LA/LAA thrombi in all patients and should be performed preferably just before but not more than 2 weeks before BMV because the possibility of LA/LAA clot cannot be completely ruled out even with sinus rhythm. Antibiotic prophylaxis is not routinely prescribed before or during the procedure, but it might be needed if the aseptic barrier has been disrupted.

#### **4.2. Anesthesia**

Most BMV procedures can be performed under mild conscious sedation. Rarely, the patient has a tender septum and experiences discomfort during the transseptal puncture and might need analgesia and more sedation and exceptionally, general anesthesia. General anesthesia is also needed in uncooperative or unstable patients or when TEE is used to guide transseptal catheterization and BMV in difficult cases.

#### **4.3. Approaches**

The antegrade transvenous transseptal approach is most commonly used. The right femoral vein is preferred because appropriate alignment of the transseptal needle with the interatrial septum facilitates septostomy. The left femoral and rarely jugular veins also can be used [17, 18]. The femoral or radial arteries are used for hemodynamic monitoring, performing catheterization, and guiding the transseptal puncture. The retrograde non-transseptal approach from the femoral artery has been utilized with acceptable results; nonetheless, higher risks of arterial damage and more hemodynamic burden arising from the trans-aortic passage of the balloon catheter have limited its use [19].

#### **4.4. Transseptal puncture**

It is the first and very important step in performing a successful BMV. The transseptal puncture is the source of complexity and complications in many patients undergoing BMV. Although the puncture site is less important than that in the MitraClip and LAA occlusion, a central or slightly low puncture is recommended. An appropriate puncture site facilitates the crossing of the mitral valve by the balloon catheter. A low puncture is especially important when the double balloon or metallic commissurotome is used. Fluoroscopy is the fundamental imaging tool used to guide the transseptal puncture but TEE and intracardiac echocardiography (ICE) can help in difficult cases or for performing a site-specific puncture.

#### **4.5. Techniques**

**4. Procedure**

104 Interventional Cardiology

been disrupted.

**4.2. Anesthesia**

**4.3. Approaches**

**4.4. Transseptal puncture**

catheterization and BMV in difficult cases.

passage of the balloon catheter have limited its use [19].

**4.1. Patient preparation**

General considerations resemble those of the other interventional procedures. Fasting is needed for at least 8 hours for solid foods and 3 hours for liquids. The patient should be hydrated according to the standard protocols for the prevention of contrast-induced acute kidney injury. BMV and even transseptal catheterization can be performed with no or minimal contrast media; accordingly, contrast-induced nephropathy is not a major issue. Rapid heart rate in patients with AF might interfere in stable balloon dilatation and should be controlled. No specific pharmacologic pretreatment is needed before BMV, but most medications (betablockers, calcium channel blockers, digoxin, etc.) are routinely continued. Warfarin should be withheld for 3 days before the procedure. Instead, heparin is needed to be infused while the patient is under therapeutic INR levels (INR < 2). Heparin infusion is stopped 4 hours before the patient arrives at the catheterization laboratory. Preprocedural TEE is of paramount importance to exclude LA/LAA thrombi in all patients and should be performed preferably just before but not more than 2 weeks before BMV because the possibility of LA/LAA clot cannot be completely ruled out even with sinus rhythm. Antibiotic prophylaxis is not routinely prescribed before or during the procedure, but it might be needed if the aseptic barrier has

Most BMV procedures can be performed under mild conscious sedation. Rarely, the patient has a tender septum and experiences discomfort during the transseptal puncture and might need analgesia and more sedation and exceptionally, general anesthesia. General anesthesia is also needed in uncooperative or unstable patients or when TEE is used to guide transseptal

The antegrade transvenous transseptal approach is most commonly used. The right femoral vein is preferred because appropriate alignment of the transseptal needle with the interatrial septum facilitates septostomy. The left femoral and rarely jugular veins also can be used [17, 18]. The femoral or radial arteries are used for hemodynamic monitoring, performing catheterization, and guiding the transseptal puncture. The retrograde non-transseptal approach from the femoral artery has been utilized with acceptable results; nonetheless, higher risks of arterial damage and more hemodynamic burden arising from the trans-aortic

It is the first and very important step in performing a successful BMV. The transseptal puncture is the source of complexity and complications in many patients undergoing BMV. Although Thus far, several techniques have been introduced. Of those, the Inoue balloon technique has gained the most popularity because of its safety and effectiveness.

#### *4.5.1. Metallic commissurotome*

A reusable metallic dilator has been developed to decrease the cost of the procedure. It has been reported that the procedure is safe, with good acute and long-term results comparable to the Inoue technique [20]. The risk of LV perforation and subsequent tamponade with the metallic device should be considered. The more demanding nature of the procedure and concerns about the reused devices have limited this technique in many countries.

#### *4.5.2. Double balloon technique*

In this antegrade transseptal technique, a balloon-tipped catheter is used to cross the mitral valve followed by introducing an exchange-length (260 cm) wire through the catheter lumen securing its end in the LV or the descending aorta. A second wire should be introduced by the same way or using a dual-lumen catheter. Two balloons (15–20 mm in diameter) are introduced over the wires and positioned across the mitral valve and inflated simultaneously [21]. In theory, two balloons side-by-side can exert a more focused pressure on the commissures than a single balloon. This technique is relatively safe and effective but is not widely used because of being more time-consuming than the Inoue technique and more hazardous because of the risk of wire-induced LV perforation. The multi-track system is a newer variant of double-balloon valvuloplasty that provides effectiveness of double-balloon inflation using a single wire.

#### *4.5.3. Inoue balloon technique*

The Inoue balloon catheter is a dumbbell-shaped balloon that self-positions in the mitral valve because of its unique physical properties and mode of inflation. It has been made from two latex layers and a middle nylon layer, giving the balloon its specialized shape and inflation characteristics. The balloon inflates in three sequential stages. The distal end of the balloon inflates at the first stage, followed by the proximal half, to facilitate positioning across the mitral valve. Finally, inflation of the waist portion of the balloon separates commissures [22]. Several balloon sizes are available (24, 26, 28, and 30 mm in diameter), and each can be inflated in a 4-mm diameter zone. The reference balloon size (RS) is calculated based on the height of the patient (patient's height in cm rounded to the nearest 0, divided by 10, and 10 added to the ratio) or the newly introduced method of inter-commissural diameter [23–25]. In patients with pliable valves, an RS-matched balloon is selected but in patients with pre-existing MR, severe commissural calcification, significant subvalvular involvement, or very severe MS (MVA ≤ 0.5 cm<sup>2</sup> ), as well as in patients with special situations where they do not need very large valve areas or in patients whose complications are more common and difficult to manage (i.e., old patients, pregnancy, etc.), a balloon 1 size smaller than the RS is chosen [23].

Immediately after the transseptal puncture, confirming the position of the needle tip in the LA and septal dilation, 70–100 IU/kg of heparin is administered intravenously to achieve an activated clotting time (ACT) of 250–300 s. A spring pigtail-like stiff wire is placed in the LA and a 14-French dilator is used to dilate both the femoral subcutaneous track and the atrial septum. A previously vented, de-aired, and calibrated slenderized balloon is sent to the LA over the wire and then reshaped to its original deflated configuration by removing the stretching tube and the wire and pulling back the gold tube. If there is any resistance when crossing the inguinal area, redilating the area using a larger dilator definitely helps. To overcome the resistance across the septum, the operator turns the balloon catheter in one or other directions or dilates the septum with a peripheral balloon (6–8 mm in diameter). By changing the projection from the anteroposterior (AP) to the right-anterior oblique (RAO), the operator introduces the stylet and while the balloon is partially inflated at its distal end acting as a floating balloon, the operator directs the balloon catheter toward and across the mitral valve with a combination of rotating anticlockwise and pulling the stylet and pushing the balloon. Free movement of the balloon in the LV toward the apex shows that the balloon has not been entrapped in the subvalvular apparatus and papillary muscles. In the final step, the distal half is fully inflated and the balloon is retracted to catch the mitral valve, followed by the inflation of the proximal and central part of the balloon until the disappearance of the waist (**Figure 3**). If any kind of distortion in the contour of the balloon is seen, the inflation should not be continued because of the possibility of balloon entrapment and subsequent severe MR. The balloon should be inflated with a diluted contrast medium (contrast-saline ratio of 1:5) to minimize the inflation-deflation period (2–4 s). It is recommended that the balloon be inflated in a stepwise fashion started 2–4 mm below the calculated RS. The balloon size is then increased 1 mm in each step, and the procedure should be stopped if any of the following criteria is met: (1) final MVA >1.5 cm<sup>2</sup> or an increase in the valve area of 50%, (2) a fall in the mean gradient by 50% or from >10 to <5 mm Hg, (3) complete opening of at least one commissure, and (4) appearance or aggravation of MR >1+ (**Table 2**).

#### **4.6. Surveillance of the procedure**

Imaging modalities combined with fluoroscopy can help to guide the procedure, assess the results, and diagnose complications. Evaluation of the mean LA pressure, transmitral valve gradient, and the contours of LA pressure between the inflations might help but they are subjected to variations and are not reliable markers of the success or occurrence of the complications. In addition, the MVA, estimated by the Gorlin formula, is affected by atrial shunt and MR. TTE is integral to guiding the procedure and should be performed between the inflations and at the end of BMV. The planimetry-derived MVA, splitting of the commissures, and the severity of MR can be readily and reliably assessed in many patients

**Figure 3.** Inoue technique. Inflation of distal end of the balloon, retracted toward mitral valve (A–B). Inflation of proximal half catching the commissures in between (C). Full inflation of the balloon disappearing the waist (D).

using TTE. TEE needs general anesthesia and is difficult to perform in the catheterization laboratory but is helpful in patients with poor echo window and in pregnant women in whom fluoroscopy is of concern. The TEE also provides superior views to verify the positioning of the balloon in the mitral valve in difficult cases (**Figure 4**).

#### **4.7. Postprocedural considerations**

the ratio) or the newly introduced method of inter-commissural diameter [23–25]. In patients with pliable valves, an RS-matched balloon is selected but in patients with pre-existing MR, severe commissural calcification, significant subvalvular involvement, or very severe MS

large valve areas or in patients whose complications are more common and difficult to manage (i.e., old patients, pregnancy, etc.), a balloon 1 size smaller than the RS is chosen [23]. Immediately after the transseptal puncture, confirming the position of the needle tip in the LA and septal dilation, 70–100 IU/kg of heparin is administered intravenously to achieve an activated clotting time (ACT) of 250–300 s. A spring pigtail-like stiff wire is placed in the LA and a 14-French dilator is used to dilate both the femoral subcutaneous track and the atrial septum. A previously vented, de-aired, and calibrated slenderized balloon is sent to the LA over the wire and then reshaped to its original deflated configuration by removing the stretching tube and the wire and pulling back the gold tube. If there is any resistance when crossing the inguinal area, redilating the area using a larger dilator definitely helps. To overcome the resistance across the septum, the operator turns the balloon catheter in one or other directions or dilates the septum with a peripheral balloon (6–8 mm in diameter). By changing the projection from the anteroposterior (AP) to the right-anterior oblique (RAO), the operator introduces the stylet and while the balloon is partially inflated at its distal end acting as a floating balloon, the operator directs the balloon catheter toward and across the mitral valve with a combination of rotating anticlockwise and pulling the stylet and pushing the balloon. Free movement of the balloon in the LV toward the apex shows that the balloon has not been entrapped in the subvalvular apparatus and papillary muscles. In the final step, the distal half is fully inflated and the balloon is retracted to catch the mitral valve, followed by the inflation of the proximal and central part of the balloon until the disappearance of the waist (**Figure 3**). If any kind of distortion in the contour of the balloon is seen, the inflation should not be continued because of the possibility of balloon entrapment and subsequent severe MR. The balloon should be inflated with a diluted contrast medium (contrast-saline ratio of 1:5) to minimize the inflation-deflation period (2–4 s). It is recommended that the balloon be inflated in a stepwise fashion started 2–4 mm below the calculated RS. The balloon size is then increased 1 mm in each step, and the procedure should be stopped if any of

(2) a fall in the mean gradient by 50% or from >10 to <5 mm Hg, (3) complete opening of at

Imaging modalities combined with fluoroscopy can help to guide the procedure, assess the results, and diagnose complications. Evaluation of the mean LA pressure, transmitral valve gradient, and the contours of LA pressure between the inflations might help but they are subjected to variations and are not reliable markers of the success or occurrence of the complications. In addition, the MVA, estimated by the Gorlin formula, is affected by atrial shunt and MR. TTE is integral to guiding the procedure and should be performed between the inflations and at the end of BMV. The planimetry-derived MVA, splitting of the commissures, and the severity of MR can be readily and reliably assessed in many patients

least one commissure, and (4) appearance or aggravation of MR >1+ (**Table 2**).

), as well as in patients with special situations where they do not need very

or an increase in the valve area of 50%,

(MVA ≤ 0.5 cm<sup>2</sup>

106 Interventional Cardiology

the following criteria is met: (1) final MVA >1.5 cm<sup>2</sup>

**4.6. Surveillance of the procedure**

After the removal of the balloon catheter, the venous access site should be compressed to achieve hemostasis. The arterial access is managed depending on the site (femoral or radial). The patient should be monitored overnight in a step-down unit to detect complications. Most patients can be discharged within 1–2 days. In patients with AF, heparin can be restarted 3–4 hours after sheath removal, followed by warfarin. Bedside TTE can detect late accumulation of pericardial effusion. The patients who have developed complications need to be closely monitored in the intensive care unit. The PHT is affected by the change in compliance immediately after BMV; therefore, it is recommended to calculate the MVA by the PHT 2–3 Balloon reference size (RS)


Balloon size selection


Inflation mode


Closing criteria


MR, mitral regurgitation; MVA, mitral valve area; RS, reference size.

**Table 2.** Inoue balloon selection and inflation protocol.

**Figure 4.** Postprocedural 3D imaging of the mitral valve revealing final mitral valve area of 1.45 cm<sup>2</sup> .

days later. Direct planimetry yields the most accurate estimate of postprocedural MVA, but it might overestimate the MVA in the first day after the procedure and should be performed 1–2 days later allowing for the early loss [26]. TEE is not routinely recommended after successful BMV. If there is severe MR, TEE is essential for detecting its exact mechanism, which is important for further decision regarding conservative or invasive intervention.
