Postocardiotomy Failure after Ross Operation: Implantation of Intravascular Flow Pump through Pulmonary Autograft

Introduction

The Impella Recover system is an intravascular left ventricular assist device that has recently been introduced into clinical practice. The inexpensive device is technically easy to insert across the aortic valve into the left ventricular cavity by a vascular graft sewn into the ascending aorta. Size and design of the device allow closure of the thoracotomy, thus permitting safe transfer of the patient to the intensive care unit. After hemodynamic stabilization, the device can be removed easily and is associated with good attributes for weaning [[1], [2], [3]]. Since intravascular microaxial pumps have only recently been introduced into clinical practice, there is as yet little experience available on their implantation in patients after aortic valve procedures.

We implanted the Impella Recover system after the failure of other methods of circulatory support in a patient after a Ross procedure. This report aims to encourage surgeons to take the device into consideration as a technique for circulatory support even in patients having undergone aortic valve procedures.

Clinical Summary

A 54-year-old patient with a bicuspid aortic valve was admitted for operative repair of a severe aortic stenosis. Due to the stenosis, the left ventricular function was reduced to 0.4. In consideration of the patient's age and personal preference, valve replacement was performed as Ross procedure. During the operation, cardioplegia was delivered in a retrograde fashion through a coronary sinus catheter and resulted in immediate electromechanical arrest of the heart. The procedure was technically uneventful; an aortic homograft was implanted in a pulmonary position.

During weaning from cardiopulmonary bypass, the patient developed low cardiac output with a rise in filling pressures and an increased need for inotropic support. Visually, an akinetic and indurated left ventricle contrasted with a good right-sided ventricular function. We considered an accidental lesion of the left coronary as a possible cause; however, flow measurement showed excellent perfusion of the left anterior descending artery. In the presence of the properly functioning right ventricle, insufficient myocardial protection during cardiopulmonary bypass was unlikely. Despite prolonged myocardial reperfusion and implantation of an intra-aortic balloon pump, the patient could not be weaned from CPB. Inotropics were increased further: a bolus of Milrinon 0.02 (mg/kg) was given. We considered further left ventricular support and opted to implant an Impella Recover microaxial pump due to its easy implantation technique and - in comparison to other devices - the relatively minimal damage to the ventricle with subsequent chances for ventricular recovery.

A 10-mm vascular graft was sewn to the ascending aorta. The device was inserted in a retrograde fashion under transesophageal echocardiographic guidance across the pulmonary autograft and into the left ventricle ([Figs. 1] and [2]). Implantation resulted in a flow of 4.2 l/min. Anticoagulation was achieved by heparinization to an activated partial thromboplastin time of 50 - 60 seconds. With an adrenalin requirement of 0.25 (µg/kg/min) and a noradrenalin requirement of 2.0 (µg/kg/min), the patient's hemodynamic condition remained uncertain and continuously deteriorated over the next 24 hours. Cardiopulmonary resuscitation was repeatedly necessary. On the first postoperative day, troponin was increased to a maximum of 1400 ng/ml, confirming severe myocardial infarction. Despite further ventricular support, the patient died two days later of global myocardial failure resistant to therapy. During autopsy, no macroscopic damage of the autograft by contact of the microvascular flow pump to the leaflets was evidenced.

Fig. 1 The Impella Recover 100 device is inserted across the pulmonary autograft and positioned in the left ventricle. Fig. 2 Impella microaxial flow pump prior to implantation. The device is inserted in a retrograde fashion through a 10-mm vascular prosthesis sewn to the ascending aorta.

Comment

We present a case of postcardiotomy failure most likely caused by a stunned myocardium in a patient after aortic valve replacement by pulmonary autograft. An intravascular flow pump was implanted for further ventricular support, which was inserted through the autograft into the left ventricle. Since implantation is technically feasible even after replacement of the aortic valve, we encourage surgeons not to exclude microaxial flow pumps as a therapeutic option in these patients, if circulatory support is required. Although implantation did not result in ventricular recovery in the current case, patients having undergone aortic valve procedures may also be candidates for this type of support device if needed. However, when choosing the device, one should keep the limited pumping capacity in mind, which under physiological conditions is around 3.0 - 4.5 l/min.

In the case presented here, no macroscopic damage of the leaflets was found after two days of pump use. Since a maximum duration of 14 days of short-term use of Impella is permitted, the function of an implanted autograft should be closely monitored.

References

• 1 Siegenthaler M P, Brehm K, Strecker T, Hanke T, Nötzold A, Olschewski M, Weyand M, Sievers H, Beyersdorf F. The Impella Recover microaxial left ventricular assist device reduces mortality for postcardiotomy failure: a three-center experience.  J Thorac Cardiovasc Surg. 2004;  127 812-822
• 2 Jurman M J, Siniawski H, Erb M, Drews T, Hetzer R. Initial experience with miniature axial flow ventricular assist devices for postcardiotomy heart failure.  Ann Thorac Surg. 2004;  77 1642-1647
• 3 Catena E, Milazzo F, Pittella G, Paino R, Colombo T, Garatti A, Vitali E, Merli M. Echocardiographic approach in a new left ventricular assist device: Impella Recover 100.  J Am Soc Echocardiog. 2004;  17 470-473