Mario F. Pompili

Port-access coronary artery bypass grafting: A proposed surgical method

Minimally invasive surgical methods have been developed to provide patients the benefits of open operations with decreased pain and suffering. We have developed a system that allows the performance of cardiopulmonary bypass and myocardial protection with cardioplegic arrest without sternotomy or thoracotomy. In a canine model, we successfully used this system to anastomose the internal thoracic artery to the left anterior descending coronary artery in nine of 10 animals. The left internal thoracic artery was dissected from the chest wall, and the pericardium was opened with the use of thoracoscopic techniques and single lung ventilation. The heart was arrested with a cold blood cardioplegic solution delivered through the central lumen of a balloon occlusion catheter (Endoaortic Clamp; Heartport, Inc., Redwood City, Calif.) in the ascending aorta, and cardiopulmonary bypass was maintained with femorofemoral bypass. An operating microscope modified to allow introduction of the 3.5x magnification objective into the chest was positioned through a 10 mm port over the site of the anastomosis. The anastomosis was performed with modified surgical instruments introduced through additional 5 mm ports. In the cadaver model (n = 7) the internal thoracic artery was harvested and the pericardium opened by means of similar techniques. A precise arteriotomy was made with microvascular thoracoscopic instruments under the modified microscope on four cadavers. In three other cadavers we assessed the exposure provided by a small anterior incision (4 to 6 cm) over the fourth intercostal space. This anterior port can assist in dissection of the distal internal thoracic artery and provides direct access to the left anterior descending, circumflex, and posterior descending arteries. We have demonstrated the potential feasibility of grafting the internal thoracic artery to coronary arteries with the heart arrested and protected, without a major thoracotomy or sternotomy.

Port-access mitral valve replacement in dogs

OBJECTIVE The objective was to assess mitral valve replacement in a minimally invasive fashion by means of port-access technology. METHODS Fifteen dogs, 28 +/- 3 kg (mean +/- standard deviation), were studied with the port-access mitral valve replacement system (Heartport, Inc., Redwood City, Calif.). Eleven dogs underwent acute studies and were sacrificed immediately after the procedure. Four dogs were allowed to recover and then were sacrificed 4 weeks after operation. Cardiopulmonary bypass was conducted by femoral cannulation with an endovascular balloon catheter for aortic occlusion, root venting, and antegrade delivery of cardioplegic solution. Catheters were inserted in the jugular vein for pulmonary artery venting and retrograde delivery of cardioplegic solution. Through the oval port, a prosthesis (St. Jude Medical, Inc., St. Paul, Minn., or CarboMedics, Inc., Austin, Texas) was inserted through the left atrial appendage and secured to the anulus with sutures. Deairing was performed. RESULTS Cardiopulmonary bypass duration was 114 +/- 24 minutes and aortic crossclamp time was 68 +/- 14 minutes. All animals were weaned from cardiopulmonary bypass in sinus rhythm. Cardiac output and pulmonary artery occlusion pressure were unchanged (2.8 +/- 0.7 L/min and 7 +/- 3 mm Hg before operation vs 2.6 +/- 0.6 L/min and 9 +/- 4 mm Hg after operation). There was no mitral regurgitation according to left ventriculography in 13 of 15 dogs. In two dogs there was interference with prosthetic valve closure by residual native anterior leaflet tissue. Pathologic examination otherwise showed normal healing without perivalvular discontinuity. Microscopic studies showed no damage to the valve surfaces. Transthoracic echocardiography of the four dogs in the long-term study showed normal ventricular and prosthetic valve function 4 weeks after the operation. CONCLUSION Mitral valve replacement with a minimally invasive method has been demonstrated in dogs. A clinical trial is in progress.

Port-access coronary artery bypass with cardioplegic arrest: acute and chronic canine studies

BACKGROUND Our goal is to perform minimally invasive coronary artery bypass grafting without sacrificing the benefits of myocardial protection with cardioplegia. METHODS Twenty-three dogs underwent acute studies and 4 dogs underwent survival studies. The left internal mammary artery was taken down using a thoracoscope. Cardiopulmonary bypass was conducted via femoral cannulas and using an endovascular balloon catheter for ascending aortic occlusion, root venting, and delivery of antegrade blood cardioplegia. Pulmonary artery venting was achieved with a jugular vein catheter. An internal mammary artery-to-coronary artery anastomosis was performed using a microscope through a 10 mm port. RESULTS All animals were weaned from cardiopulmonary bypass in sinus rhythm without inotropes. Cardiopulmonary bypass duration was 104 +/- 28 minutes and aortic clamp duration was 61 +/- 22 minutes. Cardiac output and pulmonary artery occlusion pressure were unchanged. The internal mammary artery was anastomosed to the left anterior descending artery (25) or the first diagonal (2) with patency shown in 25 of 27. One dog in the survival study had a very short internal mammary artery pedicle under tension and was euthanized for excessive postoperative hemorrhage. Three weeks postoperatively the remaining dogs had angiographically patent anastomoses, normal transthoracic echocardiograms, and histologically normal healing and patent grafts. CONCLUSIONS Endovascular cardiopulmonary bypass using a balloon catheter is effective in arresting and protecting the heart to allow thoracoscopic internal mammary artery-to-coronary artery anastomosis.

Port-access cardiac operations with cardioplegic arrest

BACKGROUND A less invasive approach to cardiac surgery has been propelled by recent advances in video-assisted surgery. Previous obstacles to minimally invasive cardiac operations with cardioplegic arrest included limitations in operative exposure, inadequate perfusion technology, and inability to provide myocardial protection. METHODS Port-access technology allows endovascular aortic occlusion, cardioplegia delivery, and left ventricular decompression. The endoaortic clamp is a triple-lumen catheter with an inflatable balloon at its distal end. Antegrade cardioplegia is delivered through a central lumen, which also acts as an aortic root vent, a second lumen is used as an aortic root pressure monitor, and a third lumen is used for balloon inflation to provide aortic occlusion. RESULTS Experimental and clinical studies have demonstrated the feasibility of port-access coronary artery bypass grafting and port-access mitral valve procedures. Endovascular cardiopulmonary bypass using the endoaortic clamp was effective in achieving cardiac arrest and myocardial protection to allow internal mammary artery to coronary artery anastomosis in a still and bloodless field. Intracardiac procedures, such as mitral valve replacement or repair, have been successfully performed clinically. CONCLUSION The port-access system effectively achieves cardiopulmonary bypass and cardioplegic arrest, thereby enabling the surgeon to perform cardiac procedures in a minimally invasive fashion. This system provides for endovascular aortic occlusion, cardioplegia delivery, and left ventricular decompression.

Closed-Chest Cardiopulmonary Bypass and Cardioplegia: Basis for Less Invasive Cardiac Surgery

BACKGROUND We developed a method of closed-chest cardiopulmonary bypass to arrest and protect the heart with cardioplegic solution. This method was used in 54 dogs and the results were retrospectively analyzed. METHODS Bypass cannulas were placed in the right femoral vessels. A balloon occlusion catheter was passed via the left femoral artery and positioned in the ascending aorta. A pulmonary artery vent was placed via the jugular vein. In 17 of the dogs retrograde cardioplegia was provided with a percutaneous coronary sinus catheter. RESULTS Cardiopulmonary bypass time was 111 +/- 27 minutes (mean +/- standard deviation) and cardiac arrest time was 66 +/- 21 minutes. Preoperative cardiac outputs were 2.9 +/- 0.70 L/min and postoperative outputs were 2.9 +/- 0.65 L/min (p = not significant). Twenty-one-French and 23F femoral arterial cannulas that allowed coaxial placement of the ascending aortic balloon catheter were tested in 3 male calves. Line pressures were higher, but not clinically limiting, with the balloon catheter placed coaxially. CONCLUSIONS Adequate cardiopulmonary bypass and cardioplegia can be achieved in the dog without opening the chest, facilitating less invasive cardiac operations. A human clinical trial is in progress.

Port-access bilateral internal mammary artery grafting for left main coronary artery disease: canine feasibility study.

Abstract Background: To extend the applications of minimal access cardiac surgery, an endovascular cardiopulmonary bypass (CPB) system that allows cardioplegia delivery and cardiac venting was used to perform bilateral internal mammary artery (IMA) bypass grafting in six dogs. Methods: The left IMA (LIMA) was taken down thoracoscopically from three left lateral chest ports, followed by the right IMA (RIMA) from the right side. One left‐sided port was extended medially 5 cm with or without rib resection, to expose the pericardium. Both IMAs were divided and exteriorized through the left anterior mediastinotomy. Flow and pedicle length were satisfactory in all cases. Femoral‐femoral bypass was used and the heart arrested with antegrade delivery of cardioplegic solution via the central lumen of a balloon catheter inflated to occlude the ascending aorta. All anastomoses were made through the mediastinotomy under direct vision. In five studies the RIMA was attached to the left anterior descending artery (LAD) and the LIMA to the circumflex, and in one study the RIMA was tunneled through the transverse sinus to the circumflex and the LIMA was anastomosed to the LAD. All animals were weaned from CPB in sinus rhythm without inotropes. CPB duration was 108 ± 27 minutes (mean ± SD) and the clamp duration was 54 ± 10 minutes. Results: Preoperative and postoperative cardiac outputs were 2.9 ± 0.71/min and 2.4 ± 0.31/min, respectively (p = NS), and corresponding pulmonary artery occlusion pressures were 6 ± 3 mmHg and 7 ± 2 mmHg, respectively (p = NS). All 12 grafts were demonstrated to be fully patent. Postmortem examination revealed well aligned pedicles and correctly grafted target vessels. Conclusion: This canine model demonstrates the potential for a less invasive approach to the surgical management of left main coronary artery disease in humans.

Port-access cardiac surgery: a system analysis.

Cardiopulmonary bypass (CPB) has been established as safe and effective, and is essential to the performance of a variety of cardiac surgical procedures. A method of closed chest CPB with cardioplegia to facilitate thoracoscopic or video-assisted cardiac surgical procedures was first proposed in 1993. The essential components included femoral vein–femoral artery CPB, and a transfemoral ascending aortic balloon catheter which could occlude the ascending aorta and arrest the heart.1 A similar system was successfully tested in dogs.2 Pulmonary artery venting and retrograde coronary sinus cardioplegia, with respective catheters placed via the jugular veins, were also used in this system.3 The clinical aims of this system were to reduce patient discomfort, morbidity, and hospital costs, and to permit faster rehabilitation and better cosmetic results. Following the first procedure using the endovascular CPB system to allow minimally invasive, or port-access, coronary artery bypass grafting (CABG) at Stanford University Medical Center in April 1995,4 over 2200 cases world-wide have been performed. This includes multivessel CABG, mitral valve replacement and repair (MVR), right heart surgical procedures, and combined procedures.5 This paper presents the technique and functional data of the bypass system as used in the first 115 patients. In particular, the pressure and flow characteristics of the peripheral catheters in providing adequate systemic perfusion, cardioplegia and cardiac decompression are analysed. The safety and efficacy of the aortic balloon occlusion catheter is also examined. The surgical results have been reported elsewhere.4,5

Minimally invasive coronary artery bypass grafting

Minimally invasive cardiac surgery has generated a tremendous amount of enthusiasm in the cardiology and cardiac surgical communities. Coronary revascularization without cardiopulmonary bypass through a small anterior thoracotomy or mediastinotomy has been introduced as an alternative to the conventional approach. An endovascular or port-access technique for cardiopulmonary bypass and cardioplegic arrest has been developed for use in cardiac surgery. This peripherally based system achieves aortic occlusion, cardioplegia delivery, and left ventricular decompression; thus, coronary revascularization and various cardiac procedures can be effectively performed in a less invasive fashion than conventional median sternotomy. Continued technical advances in minimally invasive cardiac surgery will facilitate these procedures, increase patient safety, and contribute to acceptable long-term results.

Minimally invasive cardiac surgery using the heartport technique

Abstract Background: Minimally invasive cardiac surgery has been developed in part as a result of progress in video-assisted and endovascular surgical techniques. Port-access cardiac surgery, which provides cardiopulmonary bypass, cardioplegic arrest, myocardial protection, and ventricular decompression, permits various procedures to be performed through smaller, less invasive incisions. Methods: Proper patient selection is emphasised in order to minimise potential complications with the port-access system. For port-access coronary revascularisation procedures, a limited left anterior thoracotomy allows harvesting of the internal mammary artery and access to the target coronary arteries. The ascending aorta can be exposed for placement of vein grafts. For port-access mitral valve surgery, a limited right thoracotomy provides direct visualisation of the left atrium and the mitral valve. Results: The feasibility and efficacy of port-access coronary revascularisation and mitral valve surgery have been demonstrated in experimental and clinical settings. Peripheral cardiopulmonary bypass with cardioplegic arrest has been reproducibly achieved based on indices of cardiac function. Port-access multivessel coronary revascularisation and port-access mitral valve procedures have been performed with acceptable results. Conclusions: The port-access catheter system effectively achieves peripheral cardiopulmonary bypass, aortic occlusion, cardioplegia delivery, and left ventricular decompression. Alternative, less invasive methods of coronary revascularisation and various intracardiac procedures can be performed without a conventional median sternotomy.