Despite the advances in both percutaneous and surgical treatment for coronary artery disease, there remains a significant patient population for whom these treatments either fail or inadequately resolve refractory angina. In this no-option patient population, where disease is so extensive and failure of previously attempted therapies precludes traditional treatment modalities, candidates have few alternatives. Researchers resurrecting an innovative approach first proposed in the 1950s by Goldman1 and Massimo,2 and then further studied by Munro and Allen3 in 1969, used a model that consisted of inserting a polymer tube into the left ventricle and then looping the tube, external to the heart, to a coronary artery. The flow rate average to the coronary artery was 30% of the baseline flow, and it was concluded that even if this were technically feasible, it would not successfully perfuse or revascularize the ventricular wall. While the appeal of sourcing the ventricle was certainly intriguing, the ability to demonstrate a physiological benefit had not been proven. Researchers began rethinking this concept of revascularizing the diseased myocardium by placing a cardiac shunt or conduit between the left ventricle (LV) and the anterior interventricular vein. The hypothesis of creating the LV-CA shunt was studied in animals and published in a paper entitled Direct Coronary Artery Perfusion from the Left Ventricle.4 The investigators in this experiment found that the LV-CA connection produced a high systolic antegrade flow (102 ml/minute peak) and high diastolic retrograde flow (-47 ml/minute peak), resulting in a 46% net forward flow of its baseline value based solely on ventricular sourcing. Therefore, perfusion could be achieved from systolic flow in compensated patients without alternatives.
Several groups have evaluated the use of ventricular-sourced blood to perfuse ischemia and reduce infarct size via the coronary sinus. Martin et al.5 evaluated a prosthetic left ventricle-to-coronary sinus shunt designed to provide retrograde perfusion of the venous system. Their studies showed a 73% reduction of infarct size in pigs by occluding the diagonal vessels off the left anterior descending artery. At Massachusetts General Hospital, Hayase and colleagues6 studied the placement of a conduit or implant manufactured by Percardia Inc. (Merrimack, New Hampshire). The VPASS implant was placed percutaneously between the ventricle and the coronary vein. Seven pigs were studied using the VPASS procedure, and at one-month post implantation, they underwent coronary angiography and a LV hemodynamic study to assess patency and wall motion. Dr. Hayase reported safe and potentially efficacious results in the preclinical experimentation with the VPASS implant. Dr. Peter Boekstegers et al.7 demonstrated concurrently that this procedure could be associated with significant preservation of regional myocardial function during ischemia in pigs, and could better perfuse the myocardium as evidenced in his magnetic resonance imaging perfusion studies.
The ability to percutaneously deliver a stent via the coronary sinus into the venous circulation and to provide oxygenated blood to patients with compromised arterial systems holds great promise. Preliminary studies of this procedure are currently awaiting approval in two centers: Instituto Dante Pazzanese de Cardiologia in Sao Paolo, Brazil, and Ospedale San Raffaele Milan, Italy. The Co-Investigators, Dr. Alex Abizaid, from Dante Pazzanese, Brazil, and Dr. Antonio Colombo, from San Raffaele, Italy, will implant this catheter-based ventricle-to-coronary vein bypass system, manufactured by Percardia, Inc. The percutaneous delivery system includes the VPASS Myocardial Implant (Figure 1), the VGUIDE guide catheter (Figure 2), which consists of a 14 French guide catheter with an internal dilator that is positioned in the coronary sinus, the VCROSS Myocardial Access Catheter (Figure 3), and the VPASS Delivery Catheter (Figure 4). If the results of these studies are positive and proof of the concept translates into a reproducible procedure equivalent to bypass, but performed in the catheterization laboratory, then no-option patients could benefit significantly from this approach.
1. Goldman A. Experimental methods for producing a collateral circulation to the heart directly from the ventricle. <i>J Thorac Surg</i> 1956;31:364-374. <p>2. Massimo C, Boffi L. Myocardial revascularization by a new method of carrying blood directly from the left ventricular cavity into the coronary circulation.<i> J Thorac Surg</i> 1957;34:257-264. </p><p>3. Munro I, Allen P. The possibility of myocardial revascularization by creation of a left ventriculocoronary artery fistula. <i>J Thorac Cardiovasc Surg</i> 1969;58:25-32. </p><p>4. Suehiro K, Burkhoff D. Direct coronary artery perfusion from the left ventricle. <i>J Thorac Cardiovasc Surg</i> 2001;121:307-315. </p><p>5. Martin JS, et al. LV-powered coronary sinus retroperfusion reduces infarct size in acutely ischemic pigs. <i>Ann Thorac Surg</i> 2000;69:84-89. </p><p>6. Boekstegers P, et al. Percutaneous approach to a stent-based ventricle-to-coronary vein bypass (VPASS): Comparison to catheter-based selective pressure regulated retroinfusion of the coronary vein. (Accepted for publication in <i>Eur Heart J</i>, 2005). </p><p> 7. Hayase M, et al. Catheter-based ventricle-coronary vein bypass. (Accepted for publication in <i>Catheter Cardiovasc Interv</i>, 2005). </p><p>8. Boekstegers P, Raake P, Al Ghobainy R, et al. Stent based approach for ventricle-to-coronary artery bypass. <i>Circulation</i> 2002;106:1000-1006.</p>
