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Intraoperative transesophageal echocardiography is indicated in the placement of the implantable left ventricular assist device (Heartmate®)
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INTRAOPERATIVE TRANSESOPHAGEAL ECHOCARDIOGRAPHY IS INDICATED IN THE PLACEMENT OF THE IMPLANTABLE LEFT VENTRICULAR ASSIST DEVICE (HEARTMATE@) R. M. Savage, P.M. McCarthy, S. Insler, M. O’Conner, M. Licina, E. Kraenzler, WJ. Stewart, N.J. Starr, J.D. Thomas Departments of Cardiothoracic Anesthesiology, Ca:,diology, and Thoracic and Cardiovascular Surgery The Cleveland Clinic Foundation Heart Center, Cleveland, Ohio, IJ.S.A., 44195-5076 30% of all heart transplant patients die while they are Introduction: waiting for a suitable donor heart. Consequently, implantable left vem.ricular assist devices (LVADs) are indicated in a rapidly expanding population of patients with end-stage cardiomyopathy as a prolonged bridge to transplant. Transesophageal echocardiography (TEE) has been used extensively intraoperatively, however little has been reported regarding the utility of intraoperative TEE in the placement of the implantable LVAD. Patients and Methods: Following informed consent and institutional ethical review by the Research Proposal Committee, we implanted 7 left ventricular assist devices as a bridge to heart transplant (mean = LVAD 3.2 mos.) in the previous 10 month period. The (Thermocardio Systems, Inc. , Wobum, Massachusetts, HEARTMATE@ 1000 IP) consists of a pneumatically driven pump with a left ventricular apical outflow cannula for blood withdrawal and an ascending aortic graft for blood inilow. These devices were implanted in patients with either end-stage dilated or ischemic cardiomyopathy in whom both transthoracic (TTE) as well as intraoperative TEE were performed before and after LVAD implantation. A Hewlett Packard SONOS OR Ultrasound System with a biplane transducer capable of color flow (CF), continuous wave (CW), and pulse. wave (PW) Doppler imaging in addition to acoustic quantification (AQ) edge detection with fractional area of change (end diastolic area-end systolic area/ end-diastolic area) capability was utilized on all patients. Intraoperative monitoring of all patients included left atria1 catheters, right ventricular ejection fraction (RVEF) thermodilution catheters, and routine anaesthetic monitors. Hemodynamic variables recorded intraoperatively inciuded pulmonary artery pressures (systolic, diastolic, and mean), transptdmonary pressure gradient (pulmonary artery mean pressure left atria1 pressurekuterial pressures (systolic, diastolic, and mean), central venous pressure, right ventricular ejection fraction and thermodilution cardiac output. TEE measurements included RV AQ (end-diastolic area, end-systolic area, and fractional area of change), RV dP/dt estimated from the CW Doppler interrogation of the tricuspid regurgitant flR) jet, , right atria1 and ventricular sizes, and CF determination of regurgitant lesions. Results: 5 of 7 patients have been successfully implanted with the LVAD. 4 patients have received an orthotopic heart transplant. 1 patient has been implanted with the LVAD and has been discharged to the ward service where he is undergoing physical conditioning and rehabilitation while waiting for a suitable donor. 2 patients have expired with multisystem organ failure. Pre-implantation, only the intraoperative TEE versus the ‘ITE was capable of diagnosing a LV apical thrombus and a patent foramen ovale (PFO) which was closed thereby preventing a potential right to left shunt with hypoxemia or embolization following LVAD implantation. Post-implantation, the TEE imaging and CF Doppler assisted with confirmation of correct positioning and proper functioning of the apical outflow cannula by demonstrating nonturbulent flow into LVAD and adequate filling of the left ventricle. Trivial aortic regurgitation was noted in 4 patients pre-implantation and in one patient significantly increased following LVAD placement resulting in a aortic-LV-LVAD circuit necessitating a 25% increase in LVAD pump flow compared to the right sided thermodilution cardiac
output. Pre-operatively right ventricular dysfunction was predicted in 3 patients on the basis of C/W Doppler estimation of RV dP/dt & 250 mm Hg/ set) RVEF 5 17%, and RVAQ FAC 2 16% in the setting of an elevated transpulmonary gradient Q 30 mm Hg). Post-LVAD implantation RVAQ FAC improved from 28.1% + 8.2% to 40.1% + 5.2% (p 2 0.001). RVEF improved from 11.1% + 5.8% to 20.3% or 6.2% @ 5 0.01) In one patient, clinical RV failure persisted despite improved RVEF and RVAQ FAC. Color flow Doppler demonstrated 4 + tricuspid regurgitation. The right atria1 areas decreased by an average of 15% and the right ventricular area decreased by an average of 25%. TEE estimations of pulmonary artery pressures have assisted in determining the pulmonary vascular response to LVAD and optimal timing of transplantation. Discussion: There have been previous reports of TEE being used in patients with temporary mechanical assist devices. These reports focused on the TEE’s ability to guide the process of weaning ventricular assistl. In addition reports have focused on the TEE’s ability to assist in evaluating extent of right ventricular dysfunction, the presence of atria1 or ventricular thrombi, and the detection of pericardial fluid or clot2. Magovern et al3 and Wilansky et al.4 have previously described the finding of a patent foramen ovale by contrast echocardiography in the setting of hypoxemia during left ventricular assist. In addition to these previous citings, this current report has focused on the crucial role that the TEE plays in the palcement of the implantable LVAD. Conclusions: 1) TEE can determine the degree of RV dysfunction pre-LVAD implantation 2) TEE is capable of defining the severity and etiology of RV dysfunction post-implantation 3) TEE provides crucial information in LVAD placement in identifying potential right to left shunts, embolic sources, and aortic regurgitation (a potential LVAD-aortic-LV circuit) 4) Time permitting, TEE is indicated in all patients receiving an impalntable LVAD. NOTE: A brief video will be shown if facilities permit
References: 1)
Kormos, R., Borovetz, H.S., Gasior, T., et al. Experience with mechanical support in mortally ill cardiac transplant candidates. Ann Thorac Surg, 49:261-72,199O.
2)
Brack M, Olson JDPederscn WR. Transesophageal echocardiography in patients with mechanical circulatory assist. Ann Thorac. Surg, 52:1306,1991.
3)
Magovem JA, Pae WE, Richcnbacher WE, The importance of patent foramen OVALE in left ventricular assist pumping. Trans Am Sot Artif Organs 32:449-53.1986.
4)
Baldwin RT, Duncan JM, Frazier OH et al. Patent foramen ovalc: a cause of hypoxemia in patientson left ventricular support. Ann Thorac Surg 52:865-7,199l.
INTRAOPERATIVE TRANSESOPHAGEAL ECHOCARDIOGRAPHY IS INDICATED IN THE PLACEMENT OF THE IMPLANTABLE LEFT VENTRICULAR ASSIST DEVICE (HEARTMATE@) R. M. Savage, P.M. McCarthy, S. Insler, M. O’Conner, M. Licina, E. Kraenzler, WJ. Stewart, N.J. Starr, J.D. Thomas Departments of Cardiothoracic Anesthesiology, Ca:,diology, and Thoracic and Cardiovascular Surgery The Cleveland Clinic Foundation Heart Center, Cleveland, Ohio, IJ.S.A., 44195-5076 30% of all heart transplant patients die while they are Introduction: waiting for a suitable donor heart. Consequently, implantable left vem.ricular assist devices (LVADs) are indicated in a rapidly expanding population of patients with end-stage cardiomyopathy as a prolonged bridge to transplant. Transesophageal echocardiography (TEE) has been used extensively intraoperatively, however little has been reported regarding the utility of intraoperative TEE in the placement of the implantable LVAD. Patients and Methods: Following informed consent and institutional ethical review by the Research Proposal Committee, we implanted 7 left ventricular assist devices as a bridge to heart transplant (mean = LVAD 3.2 mos.) in the previous 10 month period. The (Thermocardio Systems, Inc. , Wobum, Massachusetts, HEARTMATE@ 1000 IP) consists of a pneumatically driven pump with a left ventricular apical outflow cannula for blood withdrawal and an ascending aortic graft for blood inilow. These devices were implanted in patients with either end-stage dilated or ischemic cardiomyopathy in whom both transthoracic (TTE) as well as intraoperative TEE were performed before and after LVAD implantation. A Hewlett Packard SONOS OR Ultrasound System with a biplane transducer capable of color flow (CF), continuous wave (CW), and pulse. wave (PW) Doppler imaging in addition to acoustic quantification (AQ) edge detection with fractional area of change (end diastolic area-end systolic area/ end-diastolic area) capability was utilized on all patients. Intraoperative monitoring of all patients included left atria1 catheters, right ventricular ejection fraction (RVEF) thermodilution catheters, and routine anaesthetic monitors. Hemodynamic variables recorded intraoperatively inciuded pulmonary artery pressures (systolic, diastolic, and mean), transptdmonary pressure gradient (pulmonary artery mean pressure left atria1 pressurekuterial pressures (systolic, diastolic, and mean), central venous pressure, right ventricular ejection fraction and thermodilution cardiac output. TEE measurements included RV AQ (end-diastolic area, end-systolic area, and fractional area of change), RV dP/dt estimated from the CW Doppler interrogation of the tricuspid regurgitant flR) jet, , right atria1 and ventricular sizes, and CF determination of regurgitant lesions. Results: 5 of 7 patients have been successfully implanted with the LVAD. 4 patients have received an orthotopic heart transplant. 1 patient has been implanted with the LVAD and has been discharged to the ward service where he is undergoing physical conditioning and rehabilitation while waiting for a suitable donor. 2 patients have expired with multisystem organ failure. Pre-implantation, only the intraoperative TEE versus the ‘ITE was capable of diagnosing a LV apical thrombus and a patent foramen ovale (PFO) which was closed thereby preventing a potential right to left shunt with hypoxemia or embolization following LVAD implantation. Post-implantation, the TEE imaging and CF Doppler assisted with confirmation of correct positioning and proper functioning of the apical outflow cannula by demonstrating nonturbulent flow into LVAD and adequate filling of the left ventricle. Trivial aortic regurgitation was noted in 4 patients pre-implantation and in one patient significantly increased following LVAD placement resulting in a aortic-LV-LVAD circuit necessitating a 25% increase in LVAD pump flow compared to the right sided thermodilution cardiac
output. Pre-operatively right ventricular dysfunction was predicted in 3 patients on the basis of C/W Doppler estimation of RV dP/dt & 250 mm Hg/ set) RVEF 5 17%, and RVAQ FAC 2 16% in the setting of an elevated transpulmonary gradient Q 30 mm Hg). Post-LVAD implantation RVAQ FAC improved from 28.1% + 8.2% to 40.1% + 5.2% (p 2 0.001). RVEF improved from 11.1% + 5.8% to 20.3% or 6.2% @ 5 0.01) In one patient, clinical RV failure persisted despite improved RVEF and RVAQ FAC. Color flow Doppler demonstrated 4 + tricuspid regurgitation. The right atria1 areas decreased by an average of 15% and the right ventricular area decreased by an average of 25%. TEE estimations of pulmonary artery pressures have assisted in determining the pulmonary vascular response to LVAD and optimal timing of transplantation. Discussion: There have been previous reports of TEE being used in patients with temporary mechanical assist devices. These reports focused on the TEE’s ability to guide the process of weaning ventricular assistl. In addition reports have focused on the TEE’s ability to assist in evaluating extent of right ventricular dysfunction, the presence of atria1 or ventricular thrombi, and the detection of pericardial fluid or clot2. Magovern et al3 and Wilansky et al.4 have previously described the finding of a patent foramen ovale by contrast echocardiography in the setting of hypoxemia during left ventricular assist. In addition to these previous citings, this current report has focused on the crucial role that the TEE plays in the palcement of the implantable LVAD. Conclusions: 1) TEE can determine the degree of RV dysfunction pre-LVAD implantation 2) TEE is capable of defining the severity and etiology of RV dysfunction post-implantation 3) TEE provides crucial information in LVAD placement in identifying potential right to left shunts, embolic sources, and aortic regurgitation (a potential LVAD-aortic-LV circuit) 4) Time permitting, TEE is indicated in all patients receiving an impalntable LVAD. NOTE: A brief video will be shown if facilities permit
References: 1)
Kormos, R., Borovetz, H.S., Gasior, T., et al. Experience with mechanical support in mortally ill cardiac transplant candidates. Ann Thorac Surg, 49:261-72,199O.
2)
Brack M, Olson JDPederscn WR. Transesophageal echocardiography in patients with mechanical circulatory assist. Ann Thorac. Surg, 52:1306,1991.
3)
Magovem JA, Pae WE, Richcnbacher WE, The importance of patent foramen OVALE in left ventricular assist pumping. Trans Am Sot Artif Organs 32:449-53.1986.
4)
Baldwin RT, Duncan JM, Frazier OH et al. Patent foramen ovalc: a cause of hypoxemia in patientson left ventricular support. Ann Thorac Surg 52:865-7,199l.