**The Hybrid Operating Room**

Georg Nollert, Thomas Hartkens, Anne Figel, Clemens Bulitta, Franziska Altenbeck and Vanessa Gerhard *Siemens AG Healthcare Sector, Forchheim Germany* 

## **1. Introduction**

72 Special Topics in Cardiac Surgery

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> The integration of interventional and surgical techniques is demanding a new working environment for an interdisciplinary cardiovascular team: the hybrid operating room, where angiographic imaging capabilities are integrated in an operating suite. A deep understanding of the clinical applications, the current and future technology, and their implications on workflows is needed for a sound room design.

### **2. Clinical applications in cardiovascular therapy**

### **2.1 Definition of hybrid procedures**

The definition of hybrid procedures in the literature varies widely. A strict definition of a hybrid procedure is a major procedure that combines a conventional surgical part including a skin incision with an interventional part using some sort of catheter-based procedure guided by fluoroscopic or MRI imaging in a hybrid room without interruption. Wider definitions include procedures where the interventional and surgical parts are done in sequence, where a surgical part is only necessary in case of emergency or even minor procedures as venous cut downs. Sometimes, fluoroscopy guided interventions performed by surgeons (e.g. endovascular aortic repair in aortic abdominal aneurysms) are referred to as hybrid procedures. The term hybrid procedure in the radiology world may also refer to the combination of two imaging modalities for diagnostics or therapeutic purposes. In this chapter, the strict definition of hybrid procedures is applied and only procedures with fluoroscopic imaging are included, as interventional MRI still is in its very early stage.

### **2.2 Pediatric cardiac surgery**

Although surgery remains the treatment of choice for most congenital cardiac malformations, interventional cardiology approaches are increasingly being used in simple and even complex lesions. The percutaneous approach can be challenging due to low patient weight or poor vascular access, induced rhythm disturbances and hemodynamic compromise (Bacha et al., 2007). Difficult and complex anatomy as in double-outlet right ventricle or transposition of the great arteries, or acute turns or kinks in the pulmonary arteries of tetralogy of Fallot patients can make percutaneous procedures challenging if not impossible (Sivakumar et al., 2007). However, surgery also has its limitations. Examples are operative closure of multiple apical muscular ventricular septal defects, adequate and

The Hybrid Operating Room 75

Routine evaluation of bypass grafts is the first indication for imaging in coronary artery bypass grafting. In a study designed and published by the Vanderbilt Heart and Vascular Institute (Zhao et al., 2009), routine intraoperative completion angiography performed in a fully functional hybrid operation room detected important defects in 97 of 796 (12% of the grafts) venous coronary artery bypass grafts in 366 adult patients (14% of the patients) with complex coronary artery disease. Their findings in completion angiography at the end of the operation included suboptimal anastomoses, poor lie of the venous bypass graft, and bypasses to not diseased vessels. The angiography findings led to a change in the management, including minor adjustments of the graft, traditional surgical revision or

Surgical bypass grafting and percutaneous coronary artery revascularization are traditionally considered isolated options. A simultaneous hybrid approach may allow an opportunity to match the best strategy for a particular anatomic lesion. Revascularization of the left anterior descending artery with the left internal mammary artery is by far the best treatment option in terms of long term results. Integrating this therapy with percutaneous coronary angioplasty (hybrid procedure) offers multi-vessel revascularization through a mini-thoracotomy. Particularly in high risk patients, morbidity and mortality decreases in comparison to conventional surgery (Kon et al., 2008; Bonatti et al., 2008). A study from FuWai Hospital in Beijing (Hu et al., 2011) reports on 104 patients with multivessel coronary artery disease who were compared with the same sized group of patients undergoing offpump surgery matched by propensity scores. The patients treated with the hybrid approach had a significantly lower ICU stay and intubation time and experienced less complications in terms of bleeding and transfusions needs. At a median follow up of 18 months, patients undergoing the hybrid procedure also had a significantly higher freedom from major adverse cardiac or cerebrovascular events (99 % vs. 90.4 %; p = 0.03). The hybrid procedure

Conventional aortic valve replacement for aortic stenosis is based upon standardized guidelines with excellent outcomes particularly in younger patients at relatively low-risk and will remain the gold standard for aortic valve replacement in the upcoming years. However, transcatheter techniques have developed to valid alternatives in high-risk patients in whom conventional surgical techniques are considered too invasive and risky. The Partner trial (Leon et al., 2010) using the Edwards Sapien valve demonstrated that patients with severe aortic stenosis, who are not eligible for conventional aortic valve replacement because of too high risk, benefit overwhelmingly from TAVI in comparison to standard therapy including valvuloplasty at one year in terms of survival (Cohort B, Leon et al., 2010). In addition, 700 enrolled very high risk patients undergoing TAVI for severe aortic stenosis had comparable mortality rates to those receiving conventional aortic valve replacements at one year (Cohort A, 25% vs. 26%). The transfemoral approach was used on approximately two-thirds of TAVI patients, while the transapical approach was used in the

remaining third, unlike Cohort B where only the transfemoral approach was used.

Joint recommendations of the European Society of Cardiology and the European Association of Cardio-thoracic Surgery consider the hybrid operating room the optimal environment for these new therapeutic options (Vahanian et al., 2008). In Germany, joint recommendations of the German Society of Cardiology and the German Society of Cardiac,

percutaneous coronary interventions, resulting in optimal bypass outcomes.

was also less costly than an exclusively percutaneous strategy.

**2.4 Transcatheter aortic valve implantation (TAVI) procedures** 

**2.3 Coronary artery disease** 

lasting relief of peripheral pulmonary artery stenosis, or management of a previously implanted stenotic stent. Combining interventions and surgery into a single therapeutic procedure potentially leads to reduction of complexity, cardiopulmonary bypass time, risk, and to improved outcomes. The hybrid approach to hypoplastic left heart syndrome serves as a role model of the hybrid concept for congenital heart disease. Extracorporeal circulation and deep hypothermic circulatory arrest in infants can be avoided (or at least shortened), as shown in the extensive experience of several groups (Bacha et al., 2006; see Fig. 1).

Fig. 1. Hypoplastic left heart syndrome. Intraoperative post-Fontan evaluation of the superior and inferior venae cavae as well as the stented pulmonary arteries. Imaging: Courtesy of Prof. Berger, Dr. Ewert German Heart Center, Berlin, Germany (Nollert et al., 2010)

Completion angiography in congenital heart diseases is another important concept. Residual structural lesions after cardiac surgery for congenital heart disease may complicate the postoperative recovery and result in poor outcomes. Therefore, intraoperative assessment of the newly created anatomy in 2D with fluoroscopy may help to avoid these complications. Rotational angiography with 3D reconstruction of the soft tissues (DynaCT) results in an even better delineation of the 3D anatomy and may change surgical strategy in a substantial subgroup of patients with CHD. Holzer and colleagues (R.J. Holzer et al., 2009) reported their experience with this imaging modality with 31 patients (median age and weight: 7.5 months and 6.5 kg, respectively) who underwent 32 complex surgical procedures, most of them involving pulmonary artery and/or aortic arch reconstructions. The angiograms were performed with regular catheters in a dedicated hybrid suite. Unexpected disorder was identified in 18 procedures (56%), including right and left pulmonary artery and coronary stenoses. The therapeutic strategy was modified in nine of 32 procedures (28%) and included surgical revision, hybrid therapy, early catheterization and a change in medical management. No major adverse events were noted. These advantages may be achieved in the operating room rapidly with fast image processing and even a reduction of contrast media and ionizing radiation dose (Pedra et al., 2011). The combination of an angiography system in the OR with magnetic resonance imaging may even further reduce dose and contrast and add additional functional data (Lurz et al., 2009).

lasting relief of peripheral pulmonary artery stenosis, or management of a previously implanted stenotic stent. Combining interventions and surgery into a single therapeutic procedure potentially leads to reduction of complexity, cardiopulmonary bypass time, risk, and to improved outcomes. The hybrid approach to hypoplastic left heart syndrome serves as a role model of the hybrid concept for congenital heart disease. Extracorporeal circulation and deep hypothermic circulatory arrest in infants can be avoided (or at least shortened), as

shown in the extensive experience of several groups (Bacha et al., 2006; see Fig. 1).

Fig. 1. Hypoplastic left heart syndrome. Intraoperative post-Fontan evaluation of the superior and inferior venae cavae as well as the stented pulmonary arteries. Imaging: Courtesy of Prof. Berger, Dr. Ewert German Heart Center, Berlin, Germany (Nollert et al.,

contrast and add additional functional data (Lurz et al., 2009).

Completion angiography in congenital heart diseases is another important concept. Residual structural lesions after cardiac surgery for congenital heart disease may complicate the postoperative recovery and result in poor outcomes. Therefore, intraoperative assessment of the newly created anatomy in 2D with fluoroscopy may help to avoid these complications. Rotational angiography with 3D reconstruction of the soft tissues (DynaCT) results in an even better delineation of the 3D anatomy and may change surgical strategy in a substantial subgroup of patients with CHD. Holzer and colleagues (R.J. Holzer et al., 2009) reported their experience with this imaging modality with 31 patients (median age and weight: 7.5 months and 6.5 kg, respectively) who underwent 32 complex surgical procedures, most of them involving pulmonary artery and/or aortic arch reconstructions. The angiograms were performed with regular catheters in a dedicated hybrid suite. Unexpected disorder was identified in 18 procedures (56%), including right and left pulmonary artery and coronary stenoses. The therapeutic strategy was modified in nine of 32 procedures (28%) and included surgical revision, hybrid therapy, early catheterization and a change in medical management. No major adverse events were noted. These advantages may be achieved in the operating room rapidly with fast image processing and even a reduction of contrast media and ionizing radiation dose (Pedra et al., 2011). The combination of an angiography system in the OR with magnetic resonance imaging may even further reduce dose and

2010)

### **2.3 Coronary artery disease**

Routine evaluation of bypass grafts is the first indication for imaging in coronary artery bypass grafting. In a study designed and published by the Vanderbilt Heart and Vascular Institute (Zhao et al., 2009), routine intraoperative completion angiography performed in a fully functional hybrid operation room detected important defects in 97 of 796 (12% of the grafts) venous coronary artery bypass grafts in 366 adult patients (14% of the patients) with complex coronary artery disease. Their findings in completion angiography at the end of the operation included suboptimal anastomoses, poor lie of the venous bypass graft, and bypasses to not diseased vessels. The angiography findings led to a change in the management, including minor adjustments of the graft, traditional surgical revision or percutaneous coronary interventions, resulting in optimal bypass outcomes.

Surgical bypass grafting and percutaneous coronary artery revascularization are traditionally considered isolated options. A simultaneous hybrid approach may allow an opportunity to match the best strategy for a particular anatomic lesion. Revascularization of the left anterior descending artery with the left internal mammary artery is by far the best treatment option in terms of long term results. Integrating this therapy with percutaneous coronary angioplasty (hybrid procedure) offers multi-vessel revascularization through a mini-thoracotomy. Particularly in high risk patients, morbidity and mortality decreases in comparison to conventional surgery (Kon et al., 2008; Bonatti et al., 2008). A study from FuWai Hospital in Beijing (Hu et al., 2011) reports on 104 patients with multivessel coronary artery disease who were compared with the same sized group of patients undergoing offpump surgery matched by propensity scores. The patients treated with the hybrid approach had a significantly lower ICU stay and intubation time and experienced less complications in terms of bleeding and transfusions needs. At a median follow up of 18 months, patients undergoing the hybrid procedure also had a significantly higher freedom from major adverse cardiac or cerebrovascular events (99 % vs. 90.4 %; p = 0.03). The hybrid procedure was also less costly than an exclusively percutaneous strategy.

### **2.4 Transcatheter aortic valve implantation (TAVI) procedures**

Conventional aortic valve replacement for aortic stenosis is based upon standardized guidelines with excellent outcomes particularly in younger patients at relatively low-risk and will remain the gold standard for aortic valve replacement in the upcoming years. However, transcatheter techniques have developed to valid alternatives in high-risk patients in whom conventional surgical techniques are considered too invasive and risky. The Partner trial (Leon et al., 2010) using the Edwards Sapien valve demonstrated that patients with severe aortic stenosis, who are not eligible for conventional aortic valve replacement because of too high risk, benefit overwhelmingly from TAVI in comparison to standard therapy including valvuloplasty at one year in terms of survival (Cohort B, Leon et al., 2010). In addition, 700 enrolled very high risk patients undergoing TAVI for severe aortic stenosis had comparable mortality rates to those receiving conventional aortic valve replacements at one year (Cohort A, 25% vs. 26%). The transfemoral approach was used on approximately two-thirds of TAVI patients, while the transapical approach was used in the remaining third, unlike Cohort B where only the transfemoral approach was used.

Joint recommendations of the European Society of Cardiology and the European Association of Cardio-thoracic Surgery consider the hybrid operating room the optimal environment for these new therapeutic options (Vahanian et al., 2008). In Germany, joint recommendations of the German Society of Cardiology and the German Society of Cardiac,

The Hybrid Operating Room 77

detected by conventional completion angiography. In addition, conventional CT evaluations before discharge did not reveal any endoleak which was not previously seen in DynaCT. In addition, the hybrid operating room allowed for immediate treatment of the endoleaks, if required. In the near future, off the shelf fenestrated aortic stents will become available for the treatment of extensive aortic disease. These fenestrated stents have to be rotated in the aorta, such that the fenestrations cover the branches of the aorta. For these highly complex procedures, 3D imaging in a hybrid operating room may be extremely helpful for the

The combination of the surgical epicardial approach with the interventional endocardial approach for the treatment of rhythm disturbances in particular atrial fibrillation offers theoretically advantages over conventional endocardial or epicardial therapy alone. First reports emphasized the potential benefit. Krul and coworkers from Amsterdam (Krul et al., 2011) reported on 31 patients with atrial fibrillation (AF); thereof 13 with persistent and two with permanent AF. A minimally-invasive approach combining thoracoscopic pulmonary vein isolation (PVI) and ganglionated plexus (GP) ablation with intraoperative electrophysiological confirmation of PVI was performed in order to decrease recurrences of AF during follow-up. Results at one year follow-up were very encouraging, with 86% of the patients without recurrence of AF. A hybrid approach for drug-refractory ventricular tachycardia was described by Michowitz (Michowitz et al., 2010). Fourteen patients (most of them after previous cardiac surgery) underwent surgical ablation with an epicardial approach with concomitant electrophysiological mapping. The authors conclude that the surgical access with subxiphoid window and limited anterior thoracotomy in the

Pacemakers and implantable cardioverter defibrillators (ICD), particularly bi-ventricular systems, may be optimally implanted in a hybrid OR environment, because the hybrid operating theatre offers the required superior angulation and imaging capabilities in comparison to mobile C-arms, and the higher hygienic standards compared to cathlabs. DynaCT angiographic 3D imaging may prove useful for imaging the venous system of the heart. The coronary sinus can be depicted in 3D and than be overlaid over the fluoroscopy

Hybrid operating rooms outside cardiovascular therapies are currently more and more used in neurosurgery, traumatology, orthopedics, urology, and general surgery. Interdisciplinary

The need for hybrid operating theatres is not restricted to cardiac surgery. Vascular surgeons and neurosurgeons have equally developed hybrid procedures necessitating angiography systems in the OR. Furthermore, hybrid operating rooms are already in use by abdominal surgeons, traumatologists, orthopedic surgeons, and even urologists. Imaging needs, hygienic requirements, and room set up - particularly for neurosurgery - may be considerably different. Other surgical disciplines may want to introduce navigation systems, magnetic resonance imaging, endoscopy, biplane angiography systems, or a lateral position of anesthesia equipment. However, the hybrid operating rooms are more commonly shared with interventionalists including cardiologists, interventional radiologists,

navigation of wires and devices.

**2.7 Hybrid surgery for rhythm disturbances** 

electrophysiology lab is feasible and safe.

usage may be considered.

image to better guide placement of the left ventricular lead.

**2.8 Other applications outside cardiovascular therapy** 

Thoracic and Vascular Surgery demand a hybrid operating room or hybrid cathlab as a prerequisite for a TAVI program.

Currently two valves, the Corevalve (Medtronic, Minneapolis, MN) and the Sapien valve (Edwards, Irvine, CA) have been granted CE mark in 2007 and are successfully being implanted. Several newer generation valves aim to improve the results by more sophisticated designs to decrease the common current TAVI complications of aortic regurgitation, misplacement, and heart block. Advanced image guidance by dedicated 2D and 3D applications (e.g. syngo Aortic Valve guide, Siemens; Heart Navigator, Philips; C-THV, Paieon) may further simplify navigation and deployment of the devices. Some of the upcoming TAVI valves (e.g. Symetis Acurate, Jena Valve, Embracer, Medtronic) have dedicated mechanisms to anchor in the sinuses. Therefore, anatomically correct rotation of the valve within the aortic annulus is needed to optimally deploy the devices. 3D imaging may prove highly valuable to understand the correct relationships between the valve and the annulus.

### **2.5 Mitral valve repair**

For repair of mitral regurgitation, various devices are currently under investigation and await FDA approval. Currently, it is also not quite clear which of the devices will be used in a hybrid operating room, because some approaches will most likely be performed in regular cathlabs. In Europe, only the MitralClip Mitral valve repair system (Abbott Vascular, Santa Clara, CA) has received CE mark in 2008. Studies for FDA clearance are ongoing. The MitralClip is creating a double orifice mitral valve by connecting the free edges of the anterior and posterior leaflets at the A2 / P2 level. The Everest II trial (Feldman et al., 2011) compared the MitralClip with surgical mitral valve with repair in patients with moderate or severe mitral valve surgery, who were candidates for mitral valve surgery and demonstrated superior safety at the expense of inferior efficacy. Experimentally, prostheses for mitral und tricuspid valve replacement are under development and certainly will be available within the next years. Complex hybrid procedures may arise where the various parts of the mitral valve apparatus (e.g. chordae, leaflet and ring) are repaired on a beating heart in combination with purely interventional techniques (e.g. MitralClip). For imaging purposes, fluoroscopy will most likely be combined with 2D and 3D ultrasound and a fusion of these modalities may become helpful. The reason is that the metal devices are optimally imaged without artifacts by fluoroscopy whereas the valve itself is better evaluated with ultrasound. As an alternative to transesophageal echocardiography, the use of intracardiac 2D and 3D echo (Accunav and Accunav V, Siemens AG Healthcare, Montainview, CA) may prove useful, because it would allow avoiding general anesthesia in selected patients.

### **2.6 Thoracic endovascular aortic repair (TEVAR)**

Thoracic endovascular aortic repair (TEVAR) has become a valid alternative to open repair. In selected cases, EVAR, in combination with open surgery, is even applied for pathologies of the aortic arch and distal ascending aorta (Walsh et al., 2008). Endoleaks are common complications of EVAR and may be missed by angiographic evaluation. CT-like imaging with the angiographic C-arm enables the surgeon to diagnose this complication intraoperatively and correct it. A group from University of London (Biasi et al., 2009) demonstrated in a study of 80 patients undergoing EVAR that 3D imaging with DynaCT in the operating room was able to detect endoleaks in 5 patients. These endoleaks were not

Thoracic and Vascular Surgery demand a hybrid operating room or hybrid cathlab as a

Currently two valves, the Corevalve (Medtronic, Minneapolis, MN) and the Sapien valve (Edwards, Irvine, CA) have been granted CE mark in 2007 and are successfully being implanted. Several newer generation valves aim to improve the results by more sophisticated designs to decrease the common current TAVI complications of aortic regurgitation, misplacement, and heart block. Advanced image guidance by dedicated 2D and 3D applications (e.g. syngo Aortic Valve guide, Siemens; Heart Navigator, Philips; C-THV, Paieon) may further simplify navigation and deployment of the devices. Some of the upcoming TAVI valves (e.g. Symetis Acurate, Jena Valve, Embracer, Medtronic) have dedicated mechanisms to anchor in the sinuses. Therefore, anatomically correct rotation of the valve within the aortic annulus is needed to optimally deploy the devices. 3D imaging may prove highly valuable to understand the correct relationships between the valve and

For repair of mitral regurgitation, various devices are currently under investigation and await FDA approval. Currently, it is also not quite clear which of the devices will be used in a hybrid operating room, because some approaches will most likely be performed in regular cathlabs. In Europe, only the MitralClip Mitral valve repair system (Abbott Vascular, Santa Clara, CA) has received CE mark in 2008. Studies for FDA clearance are ongoing. The MitralClip is creating a double orifice mitral valve by connecting the free edges of the anterior and posterior leaflets at the A2 / P2 level. The Everest II trial (Feldman et al., 2011) compared the MitralClip with surgical mitral valve with repair in patients with moderate or severe mitral valve surgery, who were candidates for mitral valve surgery and demonstrated superior safety at the expense of inferior efficacy. Experimentally, prostheses for mitral und tricuspid valve replacement are under development and certainly will be available within the next years. Complex hybrid procedures may arise where the various parts of the mitral valve apparatus (e.g. chordae, leaflet and ring) are repaired on a beating heart in combination with purely interventional techniques (e.g. MitralClip). For imaging purposes, fluoroscopy will most likely be combined with 2D and 3D ultrasound and a fusion of these modalities may become helpful. The reason is that the metal devices are optimally imaged without artifacts by fluoroscopy whereas the valve itself is better evaluated with ultrasound. As an alternative to transesophageal echocardiography, the use of intracardiac 2D and 3D echo (Accunav and Accunav V, Siemens AG Healthcare, Montainview, CA) may prove useful, because it would allow avoiding general anesthesia in

Thoracic endovascular aortic repair (TEVAR) has become a valid alternative to open repair. In selected cases, EVAR, in combination with open surgery, is even applied for pathologies of the aortic arch and distal ascending aorta (Walsh et al., 2008). Endoleaks are common complications of EVAR and may be missed by angiographic evaluation. CT-like imaging with the angiographic C-arm enables the surgeon to diagnose this complication intraoperatively and correct it. A group from University of London (Biasi et al., 2009) demonstrated in a study of 80 patients undergoing EVAR that 3D imaging with DynaCT in the operating room was able to detect endoleaks in 5 patients. These endoleaks were not

prerequisite for a TAVI program.

the annulus.

**2.5 Mitral valve repair** 

selected patients.

**2.6 Thoracic endovascular aortic repair (TEVAR)** 

detected by conventional completion angiography. In addition, conventional CT evaluations before discharge did not reveal any endoleak which was not previously seen in DynaCT. In addition, the hybrid operating room allowed for immediate treatment of the endoleaks, if required. In the near future, off the shelf fenestrated aortic stents will become available for the treatment of extensive aortic disease. These fenestrated stents have to be rotated in the aorta, such that the fenestrations cover the branches of the aorta. For these highly complex procedures, 3D imaging in a hybrid operating room may be extremely helpful for the navigation of wires and devices.
