Invited Commentary

Abstract

The promise of transcatheter closure of congenital cardiac septal defects is the desirable elimination or minimization of a surgical incision as well as the avoidance of the pathophysiologic effects of cardiopulmonary bypass. This promise has been achieved to a significant extent for secundum atrial septal defects, which are now commonly closed in the cardiac catheterization laboratory. This promise has been less clearly achieved for congenital ventricular septal defects. Although ventricular septal defects have been successfully occluded by percutaneous transcatheter devices [1Fu Y. Bass J. Amin Z. et al.Transcatheter closure of perimembranous ventricular septal defects using the new Amplatzer membranous VSD occluder.J Am Coll Cardiol. 2006; 47: 319-325Abstract Full Text Full Text PDF PubMed Scopus (222) Google Scholar, 2Carminati M. Butera G. Chessa M. et al.Transcatheter closure of congenital ventricular septal defects: results of the European Registry.Eur Heart J. 2007; 28: 2361-2368Crossref PubMed Scopus (279) Google Scholar], enthusiasm for device closure has been tempered by a risk of complete heart block (3.5%) [3Zhou T. Shen X. Zhou S. et al.Atrioventricular block: a serious complication in and after transcatheter closure of perimembranous ventricular septal defects.Clin Cardiol. 2008; 31: 368-371Crossref PubMed Scopus (32) Google Scholar], which has been significantly higher than what is currently experienced with traditional surgical closure (<1%) [4Andersen H.O. de Leval M.R. Tsang V.T. Elliott M.J. Anderson R.H. Cook A.C. Is complete heart block after surgical closure of ventricular septum defects still and issue?.Ann Thorac Surg. 2006; 82: 948-957Abstract Full Text Full Text PDF PubMed Scopus (104) Google Scholar]. Many of the reports of transcatheter device closure of ventricular septal defects are from western populations in which the vast majority of defects are perimembranous. In view of the common location of the conduction axis along the edge of a perimembranous defect, I am surprised that the rate of complete heart block is not higher. On the other hand, when the ventricular septal defect (VSD) is in the doubly committed subarterial position, the conduction axis is likely to be protected by a rim of muscle [5Anderson R.H. de Leval M.R. The morphology of ventricular septal defects as related to the mechanics associated with aortic regurgitation.Semin Thorac Cardiovasc Surg Pediatr Card Surg Annu. 2006; : 140-146PubMed Google Scholar]. As such, the risk of complete heart block from device closure may be as low as that for surgical closure in these patients. Interestingly, transcatheter device closure of doubly committed subarterial VSDs has not been reported until now [6Chen Q. Chen L.-W. Wang Q.-M. Cao H. Zhang G.-C. Chen D.-Z. Intraoperative device closure of doubly committed subarterial ventricular septal defects: initial experience.Ann Thorac Surg. 2010; 90: 869-874Abstract Full Text Full Text PDF PubMed Scopus (31) Google Scholar].In the accompanying article [6Chen Q. Chen L.-W. Wang Q.-M. Cao H. Zhang G.-C. Chen D.-Z. Intraoperative device closure of doubly committed subarterial ventricular septal defects: initial experience.Ann Thorac Surg. 2010; 90: 869-874Abstract Full Text Full Text PDF PubMed Scopus (31) Google Scholar], the authors describe their minimally invasive technique and its successful application. The ability of the authors to enroll 15 of these patients for a 1-year period is impressive. This surely attests to the high activity of the center as well as to the Oriental population it serves. Importantly, these patients were carefully selected to have an isolated doubly committed subarterial defect with a significant Qp/Qs and no aortic regurgitation. The approach requires a small lower sternal incision for transventricular, transcatheter implantation without cardiopulmonary bypass. The implantation technique requires transesophageal echocardiography for imaging, which is well described in the report. Presently, the delivery system is too large to permit a percutaneous approach. The occlusion device, which is manufactured and available on the market in China, resembles an Amplatzer VSD (AGA Medical Corp, Plymouth, MN) device with important modifications. The asymmetric design helps with positioning, as well as minimizing, any interference with the aortic valve.Success in 13 of 15 patients for an innovative new technique is commendable. The failure in one case because of aortic regurgitation is understandable. More problems with aortic regurgitation might have been expected, as the position of this particular defect is likely to place the aortic valve in greater jeopardy than the conduction tissue. As we would anticipate, there was no complete heart block in the 13 successful implants, but many more implants without heart block will be required to confirm improved results compared with device closure of perimembranous defects. As with all new reports, longer-term follow-up will be important. A mean follow-up of 6 months indicates that the authors were anxious to share their exciting early results with us. Hopefully, the long-term results with regard to conduction and semilunar valve function will be as good as what we expect with traditional direct vision surgical closure. We shall see if other centers undertake this approach to the doubly committed subarterial VSD. I would expect the first will be centers in the Far East, where the prevalence of this VSD type is relatively high and the specific device required is readily available. Device developers and surgical innovators in the West may also want to take note. The promise of transcatheter closure of congenital cardiac septal defects is the desirable elimination or minimization of a surgical incision as well as the avoidance of the pathophysiologic effects of cardiopulmonary bypass. This promise has been achieved to a significant extent for secundum atrial septal defects, which are now commonly closed in the cardiac catheterization laboratory. This promise has been less clearly achieved for congenital ventricular septal defects. Although ventricular septal defects have been successfully occluded by percutaneous transcatheter devices [1Fu Y. Bass J. Amin Z. et al.Transcatheter closure of perimembranous ventricular septal defects using the new Amplatzer membranous VSD occluder.J Am Coll Cardiol. 2006; 47: 319-325Abstract Full Text Full Text PDF PubMed Scopus (222) Google Scholar, 2Carminati M. Butera G. Chessa M. et al.Transcatheter closure of congenital ventricular septal defects: results of the European Registry.Eur Heart J. 2007; 28: 2361-2368Crossref PubMed Scopus (279) Google Scholar], enthusiasm for device closure has been tempered by a risk of complete heart block (3.5%) [3Zhou T. Shen X. Zhou S. et al.Atrioventricular block: a serious complication in and after transcatheter closure of perimembranous ventricular septal defects.Clin Cardiol. 2008; 31: 368-371Crossref PubMed Scopus (32) Google Scholar], which has been significantly higher than what is currently experienced with traditional surgical closure (<1%) [4Andersen H.O. de Leval M.R. Tsang V.T. Elliott M.J. Anderson R.H. Cook A.C. Is complete heart block after surgical closure of ventricular septum defects still and issue?.Ann Thorac Surg. 2006; 82: 948-957Abstract Full Text Full Text PDF PubMed Scopus (104) Google Scholar]. Many of the reports of transcatheter device closure of ventricular septal defects are from western populations in which the vast majority of defects are perimembranous. In view of the common location of the conduction axis along the edge of a perimembranous defect, I am surprised that the rate of complete heart block is not higher. On the other hand, when the ventricular septal defect (VSD) is in the doubly committed subarterial position, the conduction axis is likely to be protected by a rim of muscle [5Anderson R.H. de Leval M.R. The morphology of ventricular septal defects as related to the mechanics associated with aortic regurgitation.Semin Thorac Cardiovasc Surg Pediatr Card Surg Annu. 2006; : 140-146PubMed Google Scholar]. As such, the risk of complete heart block from device closure may be as low as that for surgical closure in these patients. Interestingly, transcatheter device closure of doubly committed subarterial VSDs has not been reported until now [6Chen Q. Chen L.-W. Wang Q.-M. Cao H. Zhang G.-C. Chen D.-Z. Intraoperative device closure of doubly committed subarterial ventricular septal defects: initial experience.Ann Thorac Surg. 2010; 90: 869-874Abstract Full Text Full Text PDF PubMed Scopus (31) Google Scholar]. In the accompanying article [6Chen Q. Chen L.-W. Wang Q.-M. Cao H. Zhang G.-C. Chen D.-Z. Intraoperative device closure of doubly committed subarterial ventricular septal defects: initial experience.Ann Thorac Surg. 2010; 90: 869-874Abstract Full Text Full Text PDF PubMed Scopus (31) Google Scholar], the authors describe their minimally invasive technique and its successful application. The ability of the authors to enroll 15 of these patients for a 1-year period is impressive. This surely attests to the high activity of the center as well as to the Oriental population it serves. Importantly, these patients were carefully selected to have an isolated doubly committed subarterial defect with a significant Qp/Qs and no aortic regurgitation. The approach requires a small lower sternal incision for transventricular, transcatheter implantation without cardiopulmonary bypass. The implantation technique requires transesophageal echocardiography for imaging, which is well described in the report. Presently, the delivery system is too large to permit a percutaneous approach. The occlusion device, which is manufactured and available on the market in China, resembles an Amplatzer VSD (AGA Medical Corp, Plymouth, MN) device with important modifications. The asymmetric design helps with positioning, as well as minimizing, any interference with the aortic valve. Success in 13 of 15 patients for an innovative new technique is commendable. The failure in one case because of aortic regurgitation is understandable. More problems with aortic regurgitation might have been expected, as the position of this particular defect is likely to place the aortic valve in greater jeopardy than the conduction tissue. As we would anticipate, there was no complete heart block in the 13 successful implants, but many more implants without heart block will be required to confirm improved results compared with device closure of perimembranous defects. As with all new reports, longer-term follow-up will be important. A mean follow-up of 6 months indicates that the authors were anxious to share their exciting early results with us. Hopefully, the long-term results with regard to conduction and semilunar valve function will be as good as what we expect with traditional direct vision surgical closure. We shall see if other centers undertake this approach to the doubly committed subarterial VSD. I would expect the first will be centers in the Far East, where the prevalence of this VSD type is relatively high and the specific device required is readily available. Device developers and surgical innovators in the West may also want to take note. Intraoperative Device Closure of Doubly Committed Subarterial Ventricular Septal Defects: Initial ExperienceThe Annals of Thoracic SurgeryVol. 90Issue 3PreviewThe purpose of this study was to evaluate the safety and feasibility of intraoperative device closure of the doubly committed subarterial ventricular septal defect (VSD). Full-Text PDF