Ann Thorac Surg 1998;66:1829-1830
© 1998 The Society of Thoracic Surgeons
How to Do It
Alternative technique of right-sided outflow cannula insertion for right ventricular support
Todd M. Dewey, MDa,
Jonathan M. Chen, MDa,
Talia B. Spanier, MDa,
Mehmet C. Oz, MDa
a Columbia University, College of Physicians and Surgeons, New York, New York, USA
Accepted for publication June 10, 1998.
Address reprint requests to Dr Oz, Columbia-Presbyterian Medical Center, Milstein Pavilion 7-435, 177 Fort Washington Ave, New York, NY 10032
e-mail: (mco2{at}columbia.edu)
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Abstract
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Right ventricular assist devices are an important part of the armamentarium of cardiac surgeons for the treatment of right-sided circulatory failure after cardiac transplantation or insertion of a left ventricular assist device. However, right ventricular assist device insertion can be technically challenging in the setting of pulmonary hypertension because of a number of concomitant anatomic and physiologic phenomena. We present a technique for the insertion of the right ventricular assist device outflow cannula that is easier and faster to insert, and safer to explant, especially if cardiopulmonary bypass is to be avoided.
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Introduction
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Pulmonary hypertension and right-sided circulatory failure remain the major cause of early morbidity and mortality early after left ventricular assist device insertion and cardiac transplantation [1, 2]. Right ventricular assist devices (RVADs) remain an important part of the therapeutic armamentarium available to cardiac surgeons for the treatment of right-sided circulatory failure, either alone, or as a part of biventricular assistance [3, 4].
However, the insertion of RVADs in the setting of pulmonary hypertension can often be difficult because of a number of concomitant anatomic and physiologic phenomena. First, long-standing pulmonary hypertension can render the pulmonary artery thin-walled and therefore friable, making insertion difficult of both pursestring sutures and the RVAD outflow cannula itself. Bleeding often recurs after the patient has been moved or awakens in the intensive care unit and the thin-walled pursestring site is on torque. Although a sewn outflow cannula such as is available with the ABIOMED (Danvers, MA) system, or that created by the surgeon [4], provides a salutary benefit in reducing both early and late bleeding, the anastomosis can be technically challenging and mandates reinstitution of cardiopulmonary bypass. Additionally, right ventricular distension after separation from cardiopulmonary bypass in this setting can render direct visualization of the pulmonary artery, and therefore of a possible suture-line bleeding site, challenging. We present a technique for the insertion of the RVAD outflow cannula through the right ventricular outflow tract and into the pulmonary artery that obviates these concerns and that additionally provides faster insertion and easier explantation, especially if cardiopulmonary bypass is to be avoided.
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Technique
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After cannulation of the right atrium for inflow to the RVAD, two pursestring sutures are placed along the right ventricular outflow tract anteriorly. Through a single stab wound in the right ventricle, the RVAD outflow cannula is placed through the right ventricular outflow tract and directed into the pulmonary artery, where it can be palpated and adjusted. For the ABIOMED system, we use the malleable 36F straight cannula with a Dacron velour cuff to fix the shaft in a subcutaneous tunnel. Both pursestrings are then secured with snares, and right ventricular assistance is begun (Figs 1, 2).
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Fig 1. Photograph of ABIOMED cannula insertion through the right ventricular free wall. Note the puckered appearance of the right ventricle, which is gathered around the right ventricular assist device cannula. The inflow cannula to the left-sided device is seen entering the apex of the heart, our preferred approach. The left-sided outflow graft courses to the right of the right ventricular assist device outflow cannula and is sewn to the greater curvature of the aorta.
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Fig 2. Illustration of right ventricular assist device outflow cannula traversing the pulmonary valve. Note that the end of the cannula is proximal to the bifurcation of the pulmonary artery. Although significant pulmonic valve insufficiency has been reported, we have not experienced it.
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When decannulation is planned, the outflow cannula is simply removed and the pursestring sutures are sequentially secured. Because the insertion site may be made anteriorly and inferiorly, reinforcement pursestring sutures are easily placed under direct vision.
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Comment
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Cannulation of the pulmonary artery for right ventricular assistance in the setting of pulmonary hypertension can be fraught with complications because of bleeding and visualization difficulties. The method we describe is advantageous for a number of reasons, most owing to its simplicity. Insertion of the cannula through the right ventricular outflow tract allows for easy positioning into the pulmonary artery, which itself is often obscured by a dilated right ventricle. This insertion can be completed either on or off cardiopulmonary bypass, and the cannula itself is easy to adjust according to flow dynamics. Although a less frequent complication from this approach, continued cannulation site bleeding is easily repaired with reinforcing sutures in the right ventricle under direct vision with this technique. Finally, removal of the cannula at the time of RVAD explantation, or at the time of cardiac transplantation, is usually more straightforward and associated with less bleeding than the classic cannulation of the pulmonary artery.
We have used this technique for RVAD cannulation in 5 patients to date without complications of bleeding, hemolysis, or flow limitation. More importantly, trivial or no pulmonary insufficiency has been noted by transesophageal echocardiography. In vivo data in 4 cows confirm that no impedence to flows up to 6 L is identified and minimal trauma to the pulmonary artery or valve is present at explantation. The right ventricular endocardial surface is ecchymotic at the cannulation site and this is likely thrombogenic; however, the risk of stenosis after pursestring closure of the pulmonary artery is avoided. In addition, thrombus formation or infection is avoided if the sewn graft remains in place after explantation, the likely choice of most surgeons. We present this strategy as a useful adjunctive technique to be added to the armamentarium of cardiac surgeons using RVADs.
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References
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- Chen J.M., Levin H.R., Rose E.A., et al. Experience with right ventricular assist devices for perioperative right-sided circulatory failure. Ann Thorac Surg 1996;61:305-310.[Abstract/Free Full Text]
- Chen J.M., Levin H.R., Michler R.E., Prusmack C.J., Rose E.A., Aaronson K.D. Reevaluating the significance of pulmonary hypertension prior to cardiac transplantation: determination of optimal thresholds and quantification of the effect of reversibility on perioperative mortality. J Thorac Cardiovasc Surg 1997;114:627-634.[Abstract/Free Full Text]
- Argenziano M., Choudhri A.F., Moazami N., et al. A randomized, placebo-controlled trial of inhaled nitric oxide in LVAD recipients with pulmonary hypertension. Ann Thorac Surg 1998;65:340-345.[Abstract/Free Full Text]
- Williams M.R., Quaegebeur J.M., Hsu D.T., Addonizio L.J., Kichuk M.R., Oz M.C. Biventricular assist device as a bridge to transplantation in a pediatric patient. Ann Thorac Surg 1996;62:578-580.[Abstract/Free Full Text]
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Abstract
Introduction
