Ann Thorac Surg 1999;68:2326-2328
© 1999 The Society of Thoracic Surgeons
Case Reports
Isolated right ventricular assist for postcardiotomy myocardial infarction
Herbert B. Hangler, MDa,
Johannes O. Bonatti, MDa,
Herwig Antretter, MDa,
Peter Mair, MDb,
Ludwig C. Müller, MDa
a Department of Cardiac Surgery, Leopold-Franzens-University of Innsbruck, Innsbruck, Austria
b Department of Anesthesiology and Intensive Care Medicine, Leopold-Franzens–University of Innsbruck, Innsbruck, Austria
Address reprint requests to Dr Hangler, Department of Cardiac Surgery, Leopold-Franzens-University, Anichstr 35, A-6020 Innsbruck, Austria
e-mail: herbert.hangler{at}uibk.ac.at
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Abstract
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Due to myocardial infarction, profound postcardiotomy right heart failure developed in a 57-year-old man after implantation of an aortic homograft for infective aortic valve endocarditis. Despite maximum medical therapy and intraaortic balloon counterpulsation, signs of endorgan injury developed, and therefore a Thoratec (Pleasanton, CA) right ventricular assist device was implanted. After 17 days of support, myocardial and endorgan function had recovered and the fully mobilized patient was successfully weaned from support and discharged from the hospital.
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Introduction
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Acute myocardial infarction (AMI) following cardiac procedures can lead to profound right heart failure (RHF) that is refractory to pharmacologic therapy and intraaortic counterpulsation (IABP), with consequent endorgan injury. There are few reports of patients successfully weaned from isolated right ventricular assist device (RVAD) support for postcardiotomy RHF due to AMI [1]. This report illustrates successful mechanical circulatory support of a patient with profound RHF due to AMI after aortic valve replacement for infective endocarditis that could not be adequately treated with standard therapy.
A 57-year-old man presented with a 2 month history of recurrent chills, fever, and increasing exertional dyspnea. Aortic valve endocarditis with severe aortic regurgitation was diagnosed and coagulase negative staphylocci were cultured from blood samples. Because of worsening cardiac failure, inotropic support was started and the patient transferred for operation. Standard cardiopulmonary bypass (CPB) was established with moderate hypothermia to 32°C. Myocardial protection was achieved with anteretrograde cold blood cardioplegia. Uneventful aortic root replacement was performed using a cryopreserved homograft. Immediately after transfer to the intensive care unit, the patient showed signs of AMI on electrocardiogram with ST-segment elevation in the inferior leads, and RHF failure requiring inotropic support. Transesophageal echocardiography revealed right ventricular distention and hypokinesia with grossly preserved left heart function. As AMI was suspected, the patient was brought back to the operating room for reexploration and CPB was reestablished. An aortocoronary vein graft to the right coronary artery was placed on the beating heart for presumed embolic occlusion. Again, the patient was able to be weaned from CPB, but with IABP and inotropic support. During the following 24 hours, right ventricular function did not improve and inotropic support could not be reduced. Troponin T peak value (12 µg/L) confirmed myocardial injury. As signs of end-organ dysfunction, a rise in transaminase levels and decrease in urine output, developed, a pneumatic RVAD (Thoratec, Pleasanton, CA) was implanted without CPB.
As seen in Table 1, 3.3 to 4 L/min of RVAD flow in the full to empty mode provided adequate circulatory support, and the patient was weaned from the respirator 2 days after RVAD insertion. Due to renal failure, continuous hemofiltration was necessary for 4 days. Antimicrobial therapy with intravenous amoxicillin and gentamycin was administered, and oral anticoagulation was started after discontinuation of hemofiltration. In the following days, endorgan function improved, as indicated by an increase in urine output and a resolution of elevated serum transaminase levels. The patient was mobilized on support with increasing intensity. After 17 days of support, the RVAD was explanted without CPB. Simultaneously, an intraoperatively diagnosed thrombus in the right atrium was completely removed during inflow occlusion. The further recovery was uneventful and the patient was discharged on the 28th postoperative day. At 8 months follow-up, the patient is doing well, with only mild aortic insufficiency on echocardiographic reevaluation, and without thrombembolic complications or recurrent episodes of endocarditis.
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Comment
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Successful management of patients in cardiogenic shock after cardiac operations continues to present a great challenge, espescially when right heart failure is due to acute postcardiotomy myocardial infarction. Standard therapy for severe right heart failure consists of pharmacological inotropic support, volume loading, application of pulmonary vasodilators, and intraaortic counterpulsation. As the mean pulmonary artery pressure was 18 mm Hg and the central venous pressure 20 mm Hg, neither pulmonary vasodilators nor further volume loading seemed reasonable in this case. With intraaortic counterpulsation and pharmacological inotropic support, cardiac index could be stabilized between 2.0 to 2.5 L/min/m2. However, signs of end organ injury developed and therefore, in our opinion, a mechanical ventricular assist device was indicated. A venoarterial extracorporeal membrane oxygenator (ECMO) or centrifugal pump as a right ventricular assist, would have been a therapeutic option. Joyce and colleagues [2] reported a 24.4% survival rate in 168 patients with centrifugal right ventricular assist for postcardiotomy cardiogenic shock. Similar results with a survival rate of 30.4% were achieved by the Cleveland Clinic in 23 patients with a heparin coated ECMO system [3]. Nevertheless, in this patient a Thoratec RVAD was chosen because myocardial stunning after a period of 36 hours was unlikely, plus a troponin T peak value of 12µg/L indicated myocardial necrosis, and therefore need for a longer duration of mechanical support was suspected. After surgical repair of the infected aortic valve with a homograft and concomitant antimicrobial therapy according to the preoperative culture results, the infective state was not considered to be a contraindication for a mechanical assist device. There is still concern that periimplantation infections are potentially life threatening. However, there are reports that, in spite of an increased incidence of subsequent infections, these patients are not at higher risk for death or ventricular assist device-endocarditis [4]. Although in our patient the systemic infection could be controlled by antimicrobial therapy, eradication was not achieved as indicated by persistent bacteremia and positive RVAD explant culture. However, there was no evidence of device valve endocarditis after explantation. As changes in hemodynamic parameters with pump-on and pump-off measurements are critical indicators for successful weaning [5], exercise testing with 75 and 100 watts, with the RVAD flow reduced to 1.3 L/min, was performed with measurement of blood pressure, heart rate, and central venous pressure, as well as transthoracic echocardiography to evaluate right heart exercise capacity. These parameters did not deteriorate during exercise, and as expected, the patient was successfully weaned from the assist. Despite anticoagulation therapy with acenocoumarole, sinus rhythm, and adequate RVAD flow, a right atrial thrombus was found at device removal, possibly promoted by a procoagulant state in the presence of infection.
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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]
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Joyce L.D., Kiser J.C., Eales F., King R.M., Overton J.W., Toninato J.C. Experience with generally accepted centrifugal pumps. Ann Thorac Surg 1996;61:287-290.[Abstract/Free Full Text]
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Muehrcke D.D., McCarthy P.M., Stewart R.W., et al. Extracorporeal membrane oxygenation for postcardiotomy cardiogenic shock. Ann Thorac Surg 1996;61:684-691.[Abstract/Free Full Text]
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Argenziano M., Catanese K.A., Moazami N., et al. The influence of infection on survival and successful transplantation in patients with left ventricular assist devices. J Heart Lung Transplant 1997;16:822-831.[Medline]
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Termuhlen D.F., Swartz M.T., Ruzevich S.A., Reedy J.E., Pennington D.G. Hemodynamic predictors for weaning patients from ventricular assist devices. J Biomater Appl 1990;4:374-390.[Abstract/Free Full Text]
Accepted for publication April 24, 1999.
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Abstract
Introduction
