Left ventricular function during support with an asynchronous pulsatile left ventricular assist device.

BACKGROUND: Left ventricular assist devices (LVADs) are frequently used to maintain patients with severe heart failure until heart transplantation becomes possible. Some patients may experience recovery of LV function during such support. Therefore, it is essential to be able to monitor changes in LV function in this setting. METHODS: We studied LV function in 10 patients (median age 34 years, 9 male) who had LVADs implanted because of severe heart failure due to dilated cardiomyopathy a median of 4 months previously. Median pre-implant ejection fraction was 27% and all patients had been on maximal medical therapy, including intravenous inotropic support, prior to insertion of the LVAD. RESULTS: During LVAD support there were cyclical variations in LV dimensions, fractional shortening (FS) and transmitral flow, related to changes in the phase relationship of the LV and the LVAD. The "best" FS occurred when LV systole coincided with device filling and the "worst" FS when LV systole coincided with device ejection. Median FS with the pump switched off was 18% (10% to 32%). Pump-off FS was significantly greater than the "worst" FS with the pump on (5%, p = 0.002), and similar to the "best" pump-on FS (19%, p = NS). CONCLUSIONS: LV function could be studied echocardiographically during LV support and brief periods of interruption in support. Function varied according to the phase relationship of the LV and LVAD. The "best" FS measured during LVAD support was more closely related to the FS with the device switched off than the "worst" pump on FS. The "best" pump-on LV function is therefore most representative of intrinsic LV performance and can be used as a guide to recovery and the potential need for pump-off studies.     

Disease-specific remodeling of cardiac mitochondria after a left ventricular assist device

BACKGROUND: Failing hearts can exhibit elements of structural and molecular "reverse remodeling" after support with a left ventricular assist device (LVAD). The present study examined LVAD-induced remodeling of cardiac mitochondria. METHODS: Left ventricular tissue from 20 failing and 21 LVAD-supported hearts, catagorized as ischemic (ICM) or dilated (DCM) cardiomyopathy and four nonfailing hearts were studied. Myocyte mitochondrial ultrastructure was assessed by high-performance liquid chromatography determination of cardiolipin, a specific lipid component of the inner membrane, and its three major molecular species: L4, L3O, and L2O2. RESULTS: Both failing and LVAD-supported hearts exhibited a reduction in cardiolipin content that was independent of the type of cardiomyopathy. However, in failing/ICM hearts, there was a 25% increase in the L4/L3O ratio and a 70% increase in the L4/L2O2 ratio, indicating a change in cardiolipin composition. These alterations were normalized by LVAD support. In sharp contrast, molecular species ratios in DCM hearts were the same as those in nonfailing hearts regardless of whether LVAD support had been used or not. CONCLUSIONS: These data demonstrate LVAD-induced reverse remodeling of myocyte cardiolipin composition in ICM but not DCM hearts.     

Circulatory support in infants with post-cardiopulmonary bypass left ventricular dysfunction using a left ventricular assist device

Extracorporeal membrane oxygenation has been advocated as the most appropriate mode of circulatory support in the paediatric age group for post-cardiopulmonary bypass ventricular dysfunction. The results in infants who have predominantly left ventricular failure, or who require such support in order to be weaned off bypass, have been disappointing. Three infants with severe left ventricular dysfunction following cardiopulmonary bypass for correction of congenital heart defects have been managed with a left ventricular assist device. Two required this form of circulatory support in order to be weaned from full bypass while in the third infant it was instituted for progressive left ventricular dysfunction postoperatively. All three were less than 10 kg in weight. Left atrial appendage to aortic bypass was effected using a closed loop circuit with a constrained vortex pump (Biomedicus). Duration of support ranged between 40 and 146 h. One infant made a complete recovery and was able to be discharged home 20 days postoperatively. Another made a circulatory recovery such that both mechanical and inotropic support could be discontinued but had sustained massive neurological damage. The third died of progressive left ventricular dysfunction. This experience with a left ventricular assist device demonstrates that it is technically feasible in small infants, and can be performed to good effect in infants with predominant left ventricular dysfunction following cardiac surgery. It may well be more appropriate than extracorporeal membrane oxygenation in this group of patients.     

Endotoxaemia during left ventricular assist device insertion

Editor—We read with interest the excellent article byDr O’Malley and colleagues on 12 left ventricular assistdevice (LVAD) insertion patients, describing the associationbetween endotoxaemia     

Myocardium-sparing cannulation technique for left ventricular assist device support

The left atrium and the left ventricular apex are the most commonly used sites of inflow cannulation for postcardiotomy left ventricular support. A new cannulation technique that requires only an ascending aortotomy is introduced. This procedure can be undertaken with equipment present in any cardiac operating room and may prove to cause fewer complications than conventional cannulation techniques.     

Left ventricular pressure and volume unloading during pulsatile versus nonpulsatile left ventricular assist device support

BACKGROUND: Nonpulsatile axial or centrifugal pumps are the latest generation of left ventricular assist devices (LVAD). Whether left ventricular (LV) unloading and outcome in these devices is similar to pulsatile LVADs during long-term support has not been investigated. We compared LV unloading and mortality between different types of LVAD support (pulsatile versus nonpulsatile). METHODS: In 31 patients undergoing long-term LVAD implantation (nonpulsatile = 10, pulsatile = 21) preoperative and postoperative echocardiographic and hemodynamic assessment with right heart catheterization had been obtained. RESULTS: All patients had similar echocardiographic, hemodynamic, and clinical heart failure characteristics at baseline. The degree of LV pressure unloading was the same in both device types, caused by similar reduction of mean pulmonary pressure (18.6 +/- 5.1 versus 18.3 +/- 7.5 mm Hg) and pulmonary capillary wedge pressure (8.9 +/- 4.4 versus 8.0 +/- 7.0 mm Hg). Left ventricular volume unloading was pronounced with a pulsatile device owing to a statistically significant higher pump output (5.1 +/- 1.0 L/min) in comparison with nonpulsatile LVADs (3.6 +/- 0.9 L/min, p < 0.001). Echocardiographic-determined end-systolic indicators confirm this augmentation in pulsatile LVADs. Etiology or the time interval of hemodynamic reassessment had no impact in left ventricular pressure unloading, but LV volume unloading decreased between day 60 and 120 in patients with nonpulsatile LVADs. The preoperative and postoperative transplant mortality was comparable in both groups. CONCLUSIONS: Left ventricular pressure unloading is similar in patients with nonpulsatile as compared with pulsatile implantable long-term assist devices. Left ventricular volume unloading is pronounced in pulsatile LVADs.     

Cardiac resurrection after bone-marrow-derived mononuclear cell transplantation during left ventricular assist device support

We describe a novel therapy of mononuclear cell transplantation combined with a left ventricular assist device (LVAD) for severe ischemic heart failure. Significant myocardial recovery by the LVAD rarely occurs in the severely failing heart. We undertook successful mononuclear cell transplantation in a patient who sustained an acute myocardial infarction that had resulted in the LVAD therapy. The heart regained good function after cell transplantation, and the LVAD was explanted 6 weeks later. These results suggest that this novel therapy could be an alternative to cardiac transplantation for severe ischemic heart failure.