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An unexpected surgical complication of ventricular assist device implantation identified by transesophageal echocardiography: a case report
An Unexpected Surgical Complication of Ventricular Assist Device Implantation Identified by Transesophageal Echocardiography: A Case Report Min Pu, MD, Edward R. Stephenson Jr, MD, William R. Davidson Jr, MD, and Benjamin C. Sun, MD, Hershey, Pennsylvania
Ventricular assist devices are used for circulatory support for patients with cardiogenic shock and refractory heart failure. Although early and late complications of left ventricular assist devices have been reported, we report a rare surgical complica-
A
patient with an acute myocardial infarction and cardiogenic shock may require a left ventricular (LV) assist device (LVAD) for hemodynamic stabilization. A LVAD is also used as a bridge to heart transplant in patients with refractory heart failure.1 There are early and late complications associated with LVAD implantation. Early detection of the mechanical (malfunction, malposition) or nonmechanical complication (eg, thrombus, infection) is important. Scalia et al2 described the use of echocardiography in identification of complications after LVAD implantation. Other studies reported use of transesophageal echocardiography (TEE) in assessing right ventricular and LV function, and in selecting the type of assist device.3-6 We report a rare and unexpected surgical complication of LVAD implantation, which required immediate surgical correction after identification by TEE.
CASE REPORT A man in his mid-50s was transferred to our institution from a regional hospital after an acute myocardial infarction complicated by a postinfarct ventricular septal defect and cardiogenic shock. He had undergone emergency attempted surgical repair and coronary artery bypass grafting, but was unable to be stabilized. The patient was From the Division of Cardiology (M.P., W.R.D.) and Department of Cardiothoracic Surgery, Milton S. Hershey Medical Center. Reprint requests: Min Pu, MD, Division of Cardiology, H047, Milton S. Hershey Medical Center, Penn State University, 500 University Dr, PO Box 850, Hershey, PA 17033-0850 (E-mail: [email protected]). Copyright 2003 by the American Society of Echocardiography. 0894-7317/2003/$30.00 ⫹ 0 doi:10.1067/S0894-7317(03)00636-9
1194
tion of a left ventricular assist device implantation. This unexpected surgical complication was accurately identified by transesophageal echocardiography. (J Am Soc Echocardiogr 2003;16:1194-7.)
transferred to our facility after the Abiomed BVS 5000 biventricular assist system (Abiomed, Danvers, Mass) was implanted. The patient had chest pain 3 days before admission to a local hospital. Physical examination on admission showed blood pressure of 120/80 mm Hg and heart rate of 90 bpm without significant heart murmur. Electrocardiogram demonstrated Q waves in II, III, and aVF leads. His total creatine kinase was 552 U/L. He was treated with heparin, clopidogrel, and tirofiban (Aggrastat, Merck, Whitehouse Station, NJ). One day later he had recurrent chest pain relieved by nitroglycerin. Echocardiography reported normal LV function. The next day chest pain suddenly developed associated with diaphoresis, tachycardia, severe dyspnea, and bilateral rales. A new heart murmur was found. Emergency cardiac catheterization was performed. He was found to have 99% occlusion of the right coronary artery and 85% occlusion of the left anterior descending coronary artery. Left ventriculogram demonstrated a ventricular septal defect. His hemodynamic status rapidly deteriorated with the development of pulmonary edema and cardiogenic shock. He was intubated and an intraaortic balloon pump was inserted. TEE at the local hospital revealed inferior and posterior wall akinesis and a large ventricular septal defect with significant left-to-right shunt. Emergency coronary bypass with repair of ventricular septum was performed. However, the patient could not be weaned from cardiopulmonary bypass. Biventricular mechanical support was initiated with Abiomed BVS 5000 assist devices. The patient remained in critical condition with hemodynamic instability. He was transferred to our institution directly from the operating room of the local hospital. On arrival, blood pressure was 84/56 mm Hg with a pulse of 114 bpm. He was intubated and sedated. The settings of the biventricular mechanical support were, for LVAD, heart rate of 41 bpm and flow rate of 3.3 L/min; for right ventricular assist device, heart rate of 51 bpm and
Journal of the American Society of Echocardiography Volume 16 Number 11
Figure 1 Four-chamber view of left ventricle (LV). Abnormal flow was detected by color Doppler in LV during LV assist device systole. flow rate of 4.0 L/min. Hemoglobin was 7.3 g and hematocrit was 21.7%. Although the patient received multiple units of blood, his hemoglobin dropped to 6.8 g and hematocrit dropped to 19.7%. The patient was urgently taken to the operating department for mediastinal exploration for presumed postoperative exsanguinating hemorrhage. An intraoperative TEE was requested by the cardiothoracic surgeon to assess hemodynamic instability, and right ventricular and LV function. Figure 1 demonstrates the 4-chamber view of the LV in the midesophagus using multiplane TEE (Sequioa, AcusonSiemens, Mountain View, Calif). The LV was dilated. There was an unusual flow signal detected by color Doppler in the middle of the LV. This flow was pulsatile with high flow velocity, directed toward the aortic valve. Figure 2 is the long-axis view of the aortic root. There was significant high flow velocity noted in the LV outflow tract. This high flow velocity passed through a widely open aortic valve synchronous with LVAD systole, which was clearly demonstrated by color Doppler mapping. There was no aortic cannula or flow detected by TEE although extensive search in multiple views was performed. Figure 3 is a 2-dimensional image of the LV in the transgastric shortaxis view. There was an unusual tubular-like echodensity seen in the LV. Pulsed wave Doppler study detected abnormal high velocity flow in the LV (Figure 4). Multiplane 2-dimensional color Doppler images were performed, demonstrating the outlet cannula of the LVAD was in the LV. The cardiothoracic surgeon was immediately informed. Direct inspection by the cardiothoracic surgeon confirmed the diagnosis of misplacement of the LVAD cannulae. The outlet of LVAD cannula was inserted into the LV and the inlet cannula was placed in the right superior pulmonary vein. The patient was placed on cardiopulmonary bypass. The misplaced LVAD cannulae were removed. New cannulae were placed with the inlet in the LV and outlet in the ascending aorta. Figure 5
Pu et al 1195
Figure 2 Long-axis view of left ventricle (LV) and ascending aorta. High velocity flow was ejected from LV into aorta across aortic valve during LV assist device systole.
Figure 3 Short axis of left ventricle in transgastric view. Tubular structure was seen in midventricle adjacent to lateral ventricular wall with high velocity flow. depicts the results of repositioning the cannulae. The size of LV was significantly reduced in comparison with the Figure 1. There was no more abnormal color flow in the LV. Laminar blood flow toward the inlet cannula in the LV apex was demonstrated. Flow from the LVAD outlet in the ascending aorta was demonstrated in the aorta long-axis view. Blood flow did not cross the aortic valve in systole and there was no aortic regurgitation (Figure 6). Figure 7, A, illustrates the diagram of a normal implantation of Abiomed BVS 5000 LVAD with the inlet cannula in the left atrium and the outlet cannula in the ascending aorta (left atrium-aorta cannulation). Figure 7, B, illustrates a normal LV-aorta cannulation with the inlet cannula in the LV and
1196 Pu et al
Journal of the American Society of Echocardiography November 2003
Figure 4 Transgastric view. Abnormal high velocity flow was detected by pulsed wave Doppler in left ventricle. Figure 6 Long-axis view of left ventricle and ascending aorta after replacement of outlet cannula. Flow from outlet cannula was seen in ascending aorta. Aortic valve was in persistently closed position. There was no aortic regurgitation.
Figure 5 Four-chamber view after misplaced outlet cannula was removed. New cannulae were placed with inlet in left ventricle (LV) and outlet in ascending aorta. LV cavity size was reduced with laminar flow toward inlet in LV apex.
the outlet cannula in the ascending aorta; and Figure 7, C, illustrates misplacement of the outlet cannula in the LV in this case report.
DISCUSSION Mechanical circulatory assist devices have been applied clinically to support patient’s circulation in critical conditions with hemodynamic instability caused by acute or chronic cardiac pump failure or used as a bridge to heart transplant. There are a number of complications associated with mechanical circulatory assistance.2 Echocardiography, in par-
Figure 7 Schematic of implantation of Abiomed BVS 5000 left ventricular (LV) assist device in normal position with inlet cannula in left atrium (LA) and outlet cannula in ascending aorta (LA-aorta cannulation [A]) or with inlet cannula in LV and outlet cannula in ascending aorta (LVaorta cannulation [B]). Misplacement of outlet cannula in LV in current case (C).
ticular TEE, has proved to be an invaluable tool in diagnosis and management of mechanical complications associated with LVAD. Understanding of basic physiology of the LVAD is a key to diagnosis of its complications. Briefly, the LV is unloaded by the LAVD, which pumps blood from the LV directly into the aorta, bypassing the aortic valve. Unidirectional flow is ensured by xenograft-valved conduits at the inlet and outlet of the blood chamber. The LVAD drains blood from the LV and ejects it at arterial pressure into the aorta with resulting subphysiologic LV pressures.7 The retrograde aorta-to-LV gradient is very high. As a result, the aortic valve remains in a closed position during
Journal of the American Society of Echocardiography Volume 16 Number 11
normal LVAD function. LV volume is significantly decreased after implantation of a LVAD. On TEE examination, reduced LV volume with persistent closure of the aortic valve along with adequate cardiac output through a LVAD usually indicates normal function of the LVAD. When the LV is not decompressed after LVAD implantation, careful examination of cannula position should be undertaken. In this case, the first unusual sign noted by the TEE examiner was a dilated LV. The second abnormal sign attracting the examiner’s attention was a widely opened aortic valve synchronous with significant high blood flow velocity in the LVAD systole. This unusual flow pattern in the LV was detected by color and pulsed wave Doppler. The examiner was unable to locate the outlet cannula within the aorta. The combination of these findings strongly suggested abnormal LVAD connections. Diagnosis of misplacement of the LVAD cannula was correctly made. A high level of alertness for both common and uncommon complications of LVAD, even totally unexpected complications, is essential. This case report addresses that special training is necessary for a cardiothoracic surgeon who plans to implant ventricular assist devices. Echocardiographer plays an important role in identification of rare surgical complications such as the one herein reported.
Pu et al 1197
REFERENCES 1. Delgado DH, Vivek R, Ross HJ, Verma S, Smedira NG. Mechanical circulatory assistance: state of art. Circulation 2002; 106:2046-50. 2. Scalia GM, McCarthy PM, Savage RM, Smedira NG, Thomas JD. Clinical utility of echocardiography in the management of implantable ventricular assist devices. J Am Soc Echocardiogr 2000;13:754-63. 3. Simon P, Owen AN, Moritz A, Rokitansky A, Laczkovics A, Wolner E, et al. Transesophageal echocardiographic evaluation in mechanically assisted circulation. Eur J Cardiothorac Surg 1991;5:492-7. 4. Brack M, Olson JD, Pedersen WR, Goldenberg IF, Gobel FL, Pritzker MR, et al. Transesophageal echocardiography in patients with mechanical circulatory assistance. Ann Thorac Surg 1991;52:1306-9. 5. Hauptman PJ, Body S, Fox J, Couper GS, Loh E. Implantation of a pulsatile external left ventricular assist device: role of intraoperative transesophageal echocardiography. J Cardiothorac Vasc Anesth 1994;8:340-1. 6. Kececioglu D, Galal O, Halees Z, Fadely F, Wilson N, Vogt J. Transesophageal echocardiography in children with cardiac assist. Thorac Cardiovasc Surg 1994;42:21-4. 7. McCarthy PM, Savage RM, Fraser CD, Vargo R, James KB, Goormastic M, et al. Hemodynamic and physiologic changes during support with an implantable left ventricular assist device. J Thorac Cardiovasc Surg 1995;109:409-17.
Ventricular assist devices are used for circulatory support for patients with cardiogenic shock and refractory heart failure. Although early and late complications of left ventricular assist devices have been reported, we report a rare surgical complica-
A
patient with an acute myocardial infarction and cardiogenic shock may require a left ventricular (LV) assist device (LVAD) for hemodynamic stabilization. A LVAD is also used as a bridge to heart transplant in patients with refractory heart failure.1 There are early and late complications associated with LVAD implantation. Early detection of the mechanical (malfunction, malposition) or nonmechanical complication (eg, thrombus, infection) is important. Scalia et al2 described the use of echocardiography in identification of complications after LVAD implantation. Other studies reported use of transesophageal echocardiography (TEE) in assessing right ventricular and LV function, and in selecting the type of assist device.3-6 We report a rare and unexpected surgical complication of LVAD implantation, which required immediate surgical correction after identification by TEE.
CASE REPORT A man in his mid-50s was transferred to our institution from a regional hospital after an acute myocardial infarction complicated by a postinfarct ventricular septal defect and cardiogenic shock. He had undergone emergency attempted surgical repair and coronary artery bypass grafting, but was unable to be stabilized. The patient was From the Division of Cardiology (M.P., W.R.D.) and Department of Cardiothoracic Surgery, Milton S. Hershey Medical Center. Reprint requests: Min Pu, MD, Division of Cardiology, H047, Milton S. Hershey Medical Center, Penn State University, 500 University Dr, PO Box 850, Hershey, PA 17033-0850 (E-mail: [email protected]). Copyright 2003 by the American Society of Echocardiography. 0894-7317/2003/$30.00 ⫹ 0 doi:10.1067/S0894-7317(03)00636-9
1194
tion of a left ventricular assist device implantation. This unexpected surgical complication was accurately identified by transesophageal echocardiography. (J Am Soc Echocardiogr 2003;16:1194-7.)
transferred to our facility after the Abiomed BVS 5000 biventricular assist system (Abiomed, Danvers, Mass) was implanted. The patient had chest pain 3 days before admission to a local hospital. Physical examination on admission showed blood pressure of 120/80 mm Hg and heart rate of 90 bpm without significant heart murmur. Electrocardiogram demonstrated Q waves in II, III, and aVF leads. His total creatine kinase was 552 U/L. He was treated with heparin, clopidogrel, and tirofiban (Aggrastat, Merck, Whitehouse Station, NJ). One day later he had recurrent chest pain relieved by nitroglycerin. Echocardiography reported normal LV function. The next day chest pain suddenly developed associated with diaphoresis, tachycardia, severe dyspnea, and bilateral rales. A new heart murmur was found. Emergency cardiac catheterization was performed. He was found to have 99% occlusion of the right coronary artery and 85% occlusion of the left anterior descending coronary artery. Left ventriculogram demonstrated a ventricular septal defect. His hemodynamic status rapidly deteriorated with the development of pulmonary edema and cardiogenic shock. He was intubated and an intraaortic balloon pump was inserted. TEE at the local hospital revealed inferior and posterior wall akinesis and a large ventricular septal defect with significant left-to-right shunt. Emergency coronary bypass with repair of ventricular septum was performed. However, the patient could not be weaned from cardiopulmonary bypass. Biventricular mechanical support was initiated with Abiomed BVS 5000 assist devices. The patient remained in critical condition with hemodynamic instability. He was transferred to our institution directly from the operating room of the local hospital. On arrival, blood pressure was 84/56 mm Hg with a pulse of 114 bpm. He was intubated and sedated. The settings of the biventricular mechanical support were, for LVAD, heart rate of 41 bpm and flow rate of 3.3 L/min; for right ventricular assist device, heart rate of 51 bpm and
Journal of the American Society of Echocardiography Volume 16 Number 11
Figure 1 Four-chamber view of left ventricle (LV). Abnormal flow was detected by color Doppler in LV during LV assist device systole. flow rate of 4.0 L/min. Hemoglobin was 7.3 g and hematocrit was 21.7%. Although the patient received multiple units of blood, his hemoglobin dropped to 6.8 g and hematocrit dropped to 19.7%. The patient was urgently taken to the operating department for mediastinal exploration for presumed postoperative exsanguinating hemorrhage. An intraoperative TEE was requested by the cardiothoracic surgeon to assess hemodynamic instability, and right ventricular and LV function. Figure 1 demonstrates the 4-chamber view of the LV in the midesophagus using multiplane TEE (Sequioa, AcusonSiemens, Mountain View, Calif). The LV was dilated. There was an unusual flow signal detected by color Doppler in the middle of the LV. This flow was pulsatile with high flow velocity, directed toward the aortic valve. Figure 2 is the long-axis view of the aortic root. There was significant high flow velocity noted in the LV outflow tract. This high flow velocity passed through a widely open aortic valve synchronous with LVAD systole, which was clearly demonstrated by color Doppler mapping. There was no aortic cannula or flow detected by TEE although extensive search in multiple views was performed. Figure 3 is a 2-dimensional image of the LV in the transgastric shortaxis view. There was an unusual tubular-like echodensity seen in the LV. Pulsed wave Doppler study detected abnormal high velocity flow in the LV (Figure 4). Multiplane 2-dimensional color Doppler images were performed, demonstrating the outlet cannula of the LVAD was in the LV. The cardiothoracic surgeon was immediately informed. Direct inspection by the cardiothoracic surgeon confirmed the diagnosis of misplacement of the LVAD cannulae. The outlet of LVAD cannula was inserted into the LV and the inlet cannula was placed in the right superior pulmonary vein. The patient was placed on cardiopulmonary bypass. The misplaced LVAD cannulae were removed. New cannulae were placed with the inlet in the LV and outlet in the ascending aorta. Figure 5
Pu et al 1195
Figure 2 Long-axis view of left ventricle (LV) and ascending aorta. High velocity flow was ejected from LV into aorta across aortic valve during LV assist device systole.
Figure 3 Short axis of left ventricle in transgastric view. Tubular structure was seen in midventricle adjacent to lateral ventricular wall with high velocity flow. depicts the results of repositioning the cannulae. The size of LV was significantly reduced in comparison with the Figure 1. There was no more abnormal color flow in the LV. Laminar blood flow toward the inlet cannula in the LV apex was demonstrated. Flow from the LVAD outlet in the ascending aorta was demonstrated in the aorta long-axis view. Blood flow did not cross the aortic valve in systole and there was no aortic regurgitation (Figure 6). Figure 7, A, illustrates the diagram of a normal implantation of Abiomed BVS 5000 LVAD with the inlet cannula in the left atrium and the outlet cannula in the ascending aorta (left atrium-aorta cannulation). Figure 7, B, illustrates a normal LV-aorta cannulation with the inlet cannula in the LV and
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Journal of the American Society of Echocardiography November 2003
Figure 4 Transgastric view. Abnormal high velocity flow was detected by pulsed wave Doppler in left ventricle. Figure 6 Long-axis view of left ventricle and ascending aorta after replacement of outlet cannula. Flow from outlet cannula was seen in ascending aorta. Aortic valve was in persistently closed position. There was no aortic regurgitation.
Figure 5 Four-chamber view after misplaced outlet cannula was removed. New cannulae were placed with inlet in left ventricle (LV) and outlet in ascending aorta. LV cavity size was reduced with laminar flow toward inlet in LV apex.
the outlet cannula in the ascending aorta; and Figure 7, C, illustrates misplacement of the outlet cannula in the LV in this case report.
DISCUSSION Mechanical circulatory assist devices have been applied clinically to support patient’s circulation in critical conditions with hemodynamic instability caused by acute or chronic cardiac pump failure or used as a bridge to heart transplant. There are a number of complications associated with mechanical circulatory assistance.2 Echocardiography, in par-
Figure 7 Schematic of implantation of Abiomed BVS 5000 left ventricular (LV) assist device in normal position with inlet cannula in left atrium (LA) and outlet cannula in ascending aorta (LA-aorta cannulation [A]) or with inlet cannula in LV and outlet cannula in ascending aorta (LVaorta cannulation [B]). Misplacement of outlet cannula in LV in current case (C).
ticular TEE, has proved to be an invaluable tool in diagnosis and management of mechanical complications associated with LVAD. Understanding of basic physiology of the LVAD is a key to diagnosis of its complications. Briefly, the LV is unloaded by the LAVD, which pumps blood from the LV directly into the aorta, bypassing the aortic valve. Unidirectional flow is ensured by xenograft-valved conduits at the inlet and outlet of the blood chamber. The LVAD drains blood from the LV and ejects it at arterial pressure into the aorta with resulting subphysiologic LV pressures.7 The retrograde aorta-to-LV gradient is very high. As a result, the aortic valve remains in a closed position during
Journal of the American Society of Echocardiography Volume 16 Number 11
normal LVAD function. LV volume is significantly decreased after implantation of a LVAD. On TEE examination, reduced LV volume with persistent closure of the aortic valve along with adequate cardiac output through a LVAD usually indicates normal function of the LVAD. When the LV is not decompressed after LVAD implantation, careful examination of cannula position should be undertaken. In this case, the first unusual sign noted by the TEE examiner was a dilated LV. The second abnormal sign attracting the examiner’s attention was a widely opened aortic valve synchronous with significant high blood flow velocity in the LVAD systole. This unusual flow pattern in the LV was detected by color and pulsed wave Doppler. The examiner was unable to locate the outlet cannula within the aorta. The combination of these findings strongly suggested abnormal LVAD connections. Diagnosis of misplacement of the LVAD cannula was correctly made. A high level of alertness for both common and uncommon complications of LVAD, even totally unexpected complications, is essential. This case report addresses that special training is necessary for a cardiothoracic surgeon who plans to implant ventricular assist devices. Echocardiographer plays an important role in identification of rare surgical complications such as the one herein reported.
Pu et al 1197
REFERENCES 1. Delgado DH, Vivek R, Ross HJ, Verma S, Smedira NG. Mechanical circulatory assistance: state of art. Circulation 2002; 106:2046-50. 2. Scalia GM, McCarthy PM, Savage RM, Smedira NG, Thomas JD. Clinical utility of echocardiography in the management of implantable ventricular assist devices. J Am Soc Echocardiogr 2000;13:754-63. 3. Simon P, Owen AN, Moritz A, Rokitansky A, Laczkovics A, Wolner E, et al. Transesophageal echocardiographic evaluation in mechanically assisted circulation. Eur J Cardiothorac Surg 1991;5:492-7. 4. Brack M, Olson JD, Pedersen WR, Goldenberg IF, Gobel FL, Pritzker MR, et al. Transesophageal echocardiography in patients with mechanical circulatory assistance. Ann Thorac Surg 1991;52:1306-9. 5. Hauptman PJ, Body S, Fox J, Couper GS, Loh E. Implantation of a pulsatile external left ventricular assist device: role of intraoperative transesophageal echocardiography. J Cardiothorac Vasc Anesth 1994;8:340-1. 6. Kececioglu D, Galal O, Halees Z, Fadely F, Wilson N, Vogt J. Transesophageal echocardiography in children with cardiac assist. Thorac Cardiovasc Surg 1994;42:21-4. 7. McCarthy PM, Savage RM, Fraser CD, Vargo R, James KB, Goormastic M, et al. Hemodynamic and physiologic changes during support with an implantable left ventricular assist device. J Thorac Cardiovasc Surg 1995;109:409-17.