Minimally Invasive Ozaki Technique for Aortic Valve Reconstruction
This video demonstrates the minimally invasive Ozaki technique for aortic valve reconstruction, including thoracoscopic harvesting of the pericardium and Ozaki aortic valve repair technique via an upper ministernotomy. The Ozaki technique basically replaces all three aortic cusps using glutaraldehyde-treated autologous pericardium. The advantages of this method are that there is no foreign material implanted and no requirement for postoperative anticoagulation. The technique preserves the natural aortic root expansion in systole with maximal effective orifice area and the coordination of the left ventricle, aortic annulus, sinus of Valsalva, and aorta.
A 45-year-old man was admitted to the authors’ department with a history of dyspnea on exertion and palpitations. Preoperative transthoracic echocardiography (TTE) demonstrated severe aortic regurgitation with an eccentric jet directed towards the anterior mitral leaflet, secondary to a prolapsing noncoronary cusp and mild leaflet restriction. The authors performed this technique via a 4 cm upper ministernotomy. The sternum was opened and a full dose of heparin was given. Direct aortic cannulation was performed via the Seldinger technique and venous cannulation was done via the femoral vein to provide a clear operative field.
To harvest the pericardium, the authors used three trocars, two in the fourth and sixth intercostal spaces at the level of the anterior axillary line and the other in the fifth intercostal space at the level of the midaxillary line. Before harvesting the pericardium, full flow cardiopulmonary bypass was achieved to decompress the heart and deflate the lung. Similar to minimally invasive mitral valve surgery, the pericardium was opened 2 cm distal to the phrenic nerve and the incision extended anteriorly toward the sternum. Care should be taken not to damage the phrenic nerve, which may result in diaphragm paralysis.
The authors assessed the ministernotomy using the thoracoscopic camera. Traction sutures are placed on the pericardium and exteriorized through the sternotomy to facilitate the harvesting. Because a large patch of pericardium is essential in the Ozaki technique, one should go slowly and carefully until the left ventricular apex is clearly visualized. The borders of pericardial resection should be the phrenic nerves on both sides. Meticulous hemostasis is critical. Fat tissue and the left pleura is bluntly dissected to expose the pericardium on the left side, and one should go as far as possible to the left in order to have an adequate patch. The authors stopped the endoscopic harvesting when they reached the pulmonary trunk. The patch was taken out via the sternotomy. The excised pericardium was then treated with 0.6% glutaraldehyde solution with a buffer for 10 minutes. The treated pericardium was rinsed three times with physiologic saline solution for six minutes each.
The aortic clamp was applied as usual, and an aortotomy was performed. The authors’ preference for myocardial protection is Custodiol® solution, redosed every 120 minutes. The diseased aortic leaflets were carefully excised. The intercommissural distance was measured using the sizing apparatus by providing appropriate leaflet tension, similar to reproducing the annulus during diastole. Correct measurement is vital for this operation. The new pericardial cusps were then drawn on the rinsed pericardial patch, using the Ozaki template with the size corresponding to the measured value. The pericardial patch was subsequently trimmed with an original template from the treated pericardium.
The annular margin of the pericardial cusp was sutured with running 4-0 Prolene® stitches to each annulus. First, stiches were made with a ratio of 3 on pericardium to 1 on native annulus. When the length of both pericardial patch and the annulus are almost the same, a 1:1 ratio was then used. The smooth inner surface of pericardium was placed on the left ventricular side.
The authors started with the right coronary cusp. The lowest point on the native annulus was marked and sutured to the middle point of the new cusp. The pericardial cusp was sutured thoroughly to the right side, up to the top of the commissure. The needle was then straightened and pushed through the aorta at the level of the commissure. The authors performed the same suture to the left side of the cusp and ended at the left-right commissure. The left cusp was then sewn to the native aortic annulus in the same manner. The noncoronary cusp was the last one to be reconstructed. The commissural coaptation was secured with additional 4-0 Prolene® sutures. The extended wings of the cusp help to provide more tolerance to shear stress and facilitate coaptation. The result was excellent, with a windmill shape of the new reconstructed pericardial valve.
In the authors’ initial experience, they utilized peripheral femoral artery and vein cannulation, however in their most recent series, they opted for central aortic cannulation to minimize potential complications from retrograde perfusion. Two chest tubes were placed using the previously-placed trocar sites. Intraoperative transesophageal echocardiography demonstrated trivial aortic regurgitation with no gradient through the new valve. TTE three months postoperatively showed the same result.
Ozaki S, Kawase I, Yamashita H, et al. A total of 404 cases of aortic valve reconstruction with glutaraldehyde-treated autologous pericardium. J Thorac Cardiovasc Surg. 2014;147(1):301-306.