Ann Thorac Surg 2000;69:1273-1275
© 2000 The Society of Thoracic Surgeons
HOW TO DO IT
Minimally invasive resection of congenital subaortic stenosis
Kagami Miyaji, MDa,
Robert L. Hannan, MDa,
Jorge W. Ojito, CCPa,
Jeffrey A. White, MSa,
Redmond P. Burke, MDa
a Department of Cardiovascular Surgery, Miami Children’s Hospital, Miami, Florida, USA
Address reprint requests to Dr Burke, Division of Cardiovascular Surgery, Miami Children’s Hospital, 3200 SW 60 Ct, Suite 102, Miami, FL 33155-4069
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Abstract
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Fifteen consecutive patients with membranous subaortic stenosis underwent resection by a minimal-access approach through a partial upper sternotomy using a cardioscope. There were no operative deaths and no postoperative complications. Twelve patients (80%) were extubated in the operating room. The mean hospital stay was 3.1 days, and 3 patients (20%) needed blood products. Our experience demonstrates that this modified approach is a safe and effective surgical option for resection of subaortic stenosis.
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Introduction
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In congenital cardiac surgery, the need of small incisions and improved cosmetic results has continued to increase. Video-assisted thoracoscopic vascular ring division [1] and video-assisted thoracoscopic patent ductus arteriosus ligation [2] with excellent results have been reported. Several authors have used minimally invasive or less invasive procedures to repair atrial septal defect [3, 4] and ventricular septal defect [5].
Since March 1997, 15 patients with subaortic stenosis have undergone minimally invasive subaortic membrane resection through a small incision and partial upper sternotomy in our institution. Age ranged from 2 to 16 years (mean age, 6.7 years) and weight, from 12.0 to 65.0 kg (mean weight, 26.0 ± 13.8 kg). There were 10 boys and 5 girls. In all patients, the diagnosis of subaortic membranous stenosis was made by echocardiography. The preoperative systolic pressure gradient between the left ventricle and the aorta measured by echocardiography ranged from 25 to 125 mm Hg (mean gradient, 55.1 ± 22.8 mm Hg). Four patients had mild aortic regurgitation.
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Surgical technique
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After the induction of anesthesia and the placement of appropriate monitoring lines, the patient is placed in a supine position, prepared, and draped. Transesophageal echocardiography is performed to allow evaluation of the preoperative and postoperative subaortic lesions. A midline limited skin incision (approximately 4 to 9 cm in length) is made, starting from the sternal manubrium and proceeding caudad. The upper part of the sternal body is exposed, and a neurosaw (Gold cutters-GOL2; Anspach, Palm Beach, FL) is used to enter the second or third interspace on the right side, partially transecting the sternal body. The upper portion of the manubrium is divided with a standard sternal saw. A small sternal retractor is used to gradually retract the upper sternum. After pericardiotomy and the placement of traction sutures, pursestring sutures are placed on the ascending aorta just proximal to the innominate branch and the right atrial appendage.
The patient is heparinized, and the ascending aorta and the right atrium are cannulated. The patient is placed on cardiopulmonary bypass (CPB) and cooled to 28°C. A venous drainage technique using a centrifugal pump, which is called venous pull CPB, is used to achieve enough perfusion flow (80 to 100 mL · kg-1 · min-1) with a single low-profile venous cannula. The aorta is cross-clamped, and blood cardioplegia is administered through the aortic root. After cardiac arrest is achieved, carbon dioxide is infused into the operative field at 4 L/min to prevent air embolism. A vent line is placed through the dome of the left atrium.
An incision is made in the aorta and extended down into the noncoronary sinus. After exposure of the aortic valve leaflet, an intraoperative cardioscope (4-mm, 30-degree angled; Smith & Nephew Dyonics, Inc, Andover, MA) [6] is used to visualize the subaortic lesion (Fig 1A). The subaortic fibromembrane is incised and removed using blunt and sharp dissection. Care is taken to avoid injuring the conduction system and anterior leaflet of the mitral valve. Inspection of the subaortic area using an endoscope is performed to confirm a complete resection (Fig 1B).
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Fig 1. (A) After exposure of the aortic valve leaflets, an intraoperative cardioscope (4-mm, 30-degree angled) is advanced to explore the subaortic area. A discrete subaortic membrane can be seen. (B) After the subaortic fibromembrane has been incised and removed, repeat inspection of the subaortic area with an endoscope confirms that there is no residual obstructive lesion. The left ventricular outflow tract can be clearly seen.
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After the aortic incision has been closed, the left side of the heart is deaired and the aortic cross-clamp, removed. The patient is rewarmed and weaned from CPB. In 1 patient with supravalvar and valvar aortic stenosis, supravalvar aortoplasty and aortic valvoplasty were performed. Intraoperative transesophageal echocardiography is performed to inspect the aortic valve and the mitral valve and to look for any residual subaortic stenosis. Heparin sodium is reversed with protamine sulfate, and cannulas are removed. A single drain is placed in the pericardial space, and the sternum is reapproximated with interrupted stainless steel wires. Finally, the fascia is closed in two layers followed by subcuticular skin closure.
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Results
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The length of the incision ranged from 4.0 to 9.0 cm (mean length, 5.3 ± 1.6 cm). The intraoperative cardioscope was used in all 15 patients. The mean time of operation (defined as the time from skin incision to dressing of the incision) was 153.7 ± 36.2 minutes (range, 115 to 225 minutes). The mean CPB and cross-clamp times were 68.0 ± 15.9 minutes (range, 50 to 113 minutes) and 42.1 ± 14.8 minutes (range, 20 to 77 minutes), respectively. The postoperative systolic pressure gradient between the left ventricle and the aorta measured by echocardiography was 6.1 mm Hg, and there was no pressure gradient in 11 patients (73%). Twelve patients (80%) were extubated in the operating room.
There were no hospital deaths and no postoperative complications. The duration of hospital stay was 3.1 ± 1.4 days (range, 2 to 7 days). Three patients (20%) needed blood products (250 mL of red blood cells).
The mean follow-up is 15.3 months (range, 2.1 to 27.1 months). During this time, no patient has died or needed reoperation.
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Comment
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In adult cardiac surgical procedures, minimal-access techniques have been applied in the management of a variety of intracardiac lesions, including aortic and mitral valve procedures and coronary artery bypass grafting. In congenital cardiac surgical interventions, video-assisted thoracoscopic vascular ring division [1] and patent ductus arteriosus ligation [2] with excellent results were reported in 1995. Minimal-access procedures for repair of atrial septal defect [3, 4] and ventricular septal defect [5] were presented in 1998 with a primary focus on operative techniques.
New CPB strategies have been developed to accommodate the minimally invasive approach. We have advanced to a central cannulation strategy using single venous cannulation through the right atrial appendage with a modified drainage technique incorporating a centrifugal pump. As a result, we are able to achieve high flows (80 to 100 mL · kg-1 · min-1) through smaller venous cannulas with no postoperative organ failure and no low systemic venous saturation, results indicating that tissue perfusion was adequate during CPB.
The transaortic approach for subaortic stenosis was selected, and an intraoperative video-assisted cardioscope was used to expose the subaortic lesion in all patients. After resection of the subaortic fibromembrane, and the subaortic area was inspected using an endoscope to confirm that no obstructive lesion remained. In 1994, one of us with coworkers [6] reported that video-assisted cardioscopy is feasible for imaging small, inaccessible structures during repair of complex congenital heart defects. Video-assisted cardioscopy allows atraumatic visualization and magnification of inaccessible structures while avoiding vigorous cardiac manipulation and extended incisions. Minimally invasive surgical procedures in coordination with this technique can be useful, especially in complex congenital cardiac operations.
Our results suggest that resection of subaortic stenosis through a partial upper sternotomy using a cardioscope is a safe and effective procedure. Long-term follow-up and further experience will be necessary to ensure that the excellent short-time results are maintained over time.
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References
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Burke R.P., Rosenfeld H.M., Wernovsky G., Jonas R.A. Video-assisted thoracoscopic vascular ring division in infants and children. J Am Coll Cardiol 1995;25:943-947.[Abstract]
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Burke R.P., Wernovsky G., van der Velde M., Hansen D., Castañeda A.R. Video-assisted thoracoscopic surgery for con-genital heart disease. J Thorac Cardiovasc Surg 1995;109:499-508.[Abstract/Free Full Text]
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Black M.D., Freedom R.M. Minimally invasive repair of atrial septal defects. Ann Thorac Surg 1998;65:765-767.[Abstract/Free Full Text]
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Barbero-Marcial M., Tanamati C., Jatene M.B., Atik E., Jatene A.D. Transxiphoid approach without median sternotomy for the repair of atrial septal defects. Ann Thorac Surg 1998;65:771-774.[Abstract/Free Full Text]
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Lin P.J., Chang C.-H., Chu J.-J., et al. Minimally invasive cardiac surgical techniques in the closure of ventricular septal defect. Ann Thorac Surg 1998;65:165-170.[Abstract/Free Full Text]
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Burke R.P., Michielon G., Wernovsky G. Video-assisted cardioscopy in congenital heart operations. Ann Thorac Surg 1994;58:864-868.[Abstract]
Accepted for publication November 16, 1999.
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Abstract
Introduction
