Replacement of an intracorporeal left ventricular assist device

An intracorporeal left ventricular assist device was placed as a bridge to cardiac transplantation in a 51-year-old man after an acute myocardial infarction. After 126 days of support, the left ventricular assist device malfunctioned. The pump, which had a tear in its pneumatic drive line, was successfully replaced.     

Assessment of timing right ventricular assist device withdrawal using left ventricular assist device filling characteristics

Right ventricular assist devices (RVAD) are often needed on a short term basis in patients who develop RV failure after left ventricular assist device (LVAD) implantation. The purpose of this study was to use LVAD filling characteristics to help determine the timing for weaning a patient from RVAD support. Eleven patients (age 50 years +/- 15) supported with an LVAD (Novacor) and an RVAD (Biomedicus or ABIOMED) were studied. Eight patients (RV recovery group) were studied before RVAD removal and all were successfully weaned from RVAD support. Five patients (RV failure group) were studied at the time of RVAD placement to determine baseline characteristics of RV failure. Simultaneous measures of LVAD volume and routine hemodynamics were recorded during periods of high and low RVAD flow. The LVAD filling was assessed as the first derivative of LVAD volume and the mean filling rate for each cardiac cycle was calculated and averaged over 10 sec periods at both RVAD flows. The mean pump rate corrected filling rates did not change in the RV recovery group (89 +/- 13 vs. 87 +/- 8 ml/beat) and significantly decreased in the RV failure group (84 +/- 19 vs. 62 +/- 22 ml/ beat) (p < 0.001) with decreasing RVAD flow. These data suggest that LVAD filling rates may be used to assess RV systolic function and the proper timing of RVAD removal in selected patients.     

Emergency versus elective/urgent left ventricular assist device implantation

BACKGROUND: The risk and outcome in patients undergoing left ventricular assist device (LVAD) implantation on an emergency basis is still unclear. METHODS: Since April 1993, 40 patients received a Novacor and 8 patients a Heartmate LVAD in our institution. Patients with emergency LVAD placement were compared with the remainder in a retrospective manner. Parameters studied included underlying heart disease, preimplantation dysfunction of kidney, liver, lung, and cerebrum, interval of mechanical support, outcome, and complications. RESULTS: Patients with emergency LVAD placement predominantly were seen with postcardiotomy heart failure (47%) or acute myocarditis (20%) (group A) whereas elective and urgent candidates for LVAD implantation mainly had dilative cardiomyopathy (67%) or ischemic heart disease (30%) (group B). The incidence of secondary organ failure was significantly higher for all organs in group A patients (p < .01). Mean support interval in patients who underwent emergency LVAD implantation was lower (74+/-79 days vs 115+/-80 days), and fewer patients could be forwarded to heart transplantation in this group (22% vs 78%, p < .01). Moreover, bleeding complications were increased in group A (66% vs 30%, p < .01), but not thromboembolism and infection. CONCLUSION: In conclusion, the overall success rate after emergency LVAD implantation was lower, with bleeding being the most frequent complication. To achieve acceptable outcomes in disastrous situations, LVADs should be placed as early as possible.     

Long-distance transportation of patients with a paracorporeal left ventricular assist device

Patients in cardiogenic shock refractory to basic medical therapy may require specialised assistance in a multispeciality environment distant to the institution where they are first admitted. In such situations, transportation of these critical patients may be difficult and involve many risks. Here we describe the case histories of two patients who underwent implantation of a paracorporeal left ventricular assist device and were transferred to specialised institutions for extended treatment. The distance of transportation was 400 km and the patients were transported by ambulance and helicopter. Some aspects of logistics and complexity of long-distance transportation are also commented on.     

Influence of longer term left ventricular assist device support on valvular regurgitation

The authors previously published data that describe acute alterations in ventricular dimensions and in the severity of mitral and tricuspid regurgitation (MR/TR) after initiation of left ventricular assist device (LVAD) pumping. In the current study, measurements of ventricular size and regurgitant jet area acquired after LVAD implantation are presented. Eight patients had LVAD implanted pending cardiac transplantation (duration of assist 70-279 days; mean, 162 +/- 29 days). Echocardiograms were obtained at the time of LVAD implant and later during LVAD support (mean time for late echo, 95 +/- 32 days post-implant). Comparisons of pre-implant with late post-implant data showed: increased TR jet area (4.8 +/- 1.0 cm2 vs. 8.0 +/- 1.7 cm2 P < 0.05); increased right ventricular (RV) end-systolic dimension (31 +/- 4 vs 40 +/- 5 mm, P < 0.05); and increased RV end-diastolic dimension (35 +/- 4 vs. 45 +/- 5 mm, P < 0.065). Decreased MR jet area and decreased LV dimensions (P < 0.05) also were noted on comparison of pre-implant and late post-implant data. There were no significant differences between any immediate post-implant and late post-implant echocardiographic measurements. No patient had clinical evidence of RV failure. LV mechanical assist causes an acute increase in TR, presumably by volume loading the RV. TR and RV enlargement persisted but did not discernibly worsen on subsequent post-implant echocardiograms. LV dimensions and MR remained less than the pre-implant values on later post-implant determinations.     

Extracorporeal life support as a post left ventricular assist device implant supplement

Extracorporeal life support (ECLS) is indicated following left ventricular assist device (LVAD) implant for right heart failure or pulmonary dysfunction. From December 1991 to December 1996, 100 patients were supported with the implantable HeartMate LVAD. Of these, 12 patients were supported with ECLS post LVAD implant. Pre-operatively, 10 patients (83%) were on an intra-aortic balloon pump, 9 patients (75%) were intubated, and 8 patients (67%) required ECLS bridge to LVAD implant. Six patients (50%) were men, and patient age ranged from 28 to 63 years (mean 46 +/- 10 years). Duration of ECLS averaged 3 +/- 2 days (range, 1-9 days). Eight patients (67%) required a right ventricular assist device (RVAD) with an ECLS circuit, three patients (25%) required peripheral veno-venous ECLS, and one patient peripheral veno-arterial ECLS. Forty-five percent supported with ECLS post LVAD survived to transplant compared with the 81% supported with LVAD only. Early in this experience, three patients had RVAD support only and all three patients died. RVAD support (with or without ECLS) was 11% overall and declined from 14% in the first 50 patients to 8% in the second 50. ECLS post LVAD is relatively uncommon and its use is associated with reduced survival, but helps salvage these critically ill patients.     

Hemodynamic and physiologic changes during support with an implantable left ventricular assist device

To evaluate hemodynamic effectiveness and physiologic changes on the HeartMate 1000 IP left ventricular assist device (Thermo Cardiosystems, Inc., Woburn, Mass.), we studied 25 patients undergoing bridge to heart transplantation (35 to 63 years old, mean 50 years). All were receiving inotropic agents before left ventricular assist device implantation, 21 (84%) were supported with a balloon pump, and 7 (28%) were supported by extracorporeal membrane oxygenation. Six patients died, primarily of right ventricular dysfunction and multiple organ failure. Nineteen (76%) were rehabilitated, received a donor heart, and were discharged (100% survival after transplantation). Pretransplantation duration of support averaged 76 days (22 to 153 days). No thromboembolic events occurred in more than 1500 patient-days of support with only antiplatelet medications. Significant hemodynamic improvement was measured (before implantation to before explantation) in cardiac index (1.7 +/- 0.3 to 3.1 +/- 0.8 L/min per square meter; p < 0.001), left atrial pressure (23.7 +/- 7 to 9 +/- 7.5 mm Hg; p < 0.001), pulmonary artery pressure, pulmonary vascular resistance, and right ventricular volumes and ejection fraction. Both creatinine and blood urea nitrogen levels were significantly higher before implantation in patients who died while receiving support. Renal and liver function returned to normal before transplantation. We conclude that support with the HeartMate device improved hemodynamic and subsystem function before transplantation. Long-term support with the HeartMate device has a low risk of thromboemboli and makes a clinical trial of a portable HeartMate device a realistic alternative to medical therapy.     

Long-term in vivo left ventricular assist device study with a titanium centrifugal pump

A totally implantable centrifugal artificial heart has been developed. The plastic prototype, Gyro PI 601, passed 2 day hemodynamic tests as a functional total artificial heart, 2 week screening tests for antithrombogenicity, and 1 month system feasibility. Based on these results, a metallic prototype, Gyro PI 702, was subjected to in vivo left ventricular assist device (LVAD) studies. The pump system employed the Gyro PI 702, which has the same inner dimensions and the same characteristics as the Gyro PI 601, including an eccentric inlet port, a double pivot bearing system, and a magnet coupling system. The PI 702 is driven with the Vienna DC brushless motor actuator. For the in vivo LVAD study, the pump actuator package was implanted in the preperitoneal space in two calves, from the left ventricular apex to the descending aorta. Case 1 achieved greater than 9 month survival without any complications, at an average flow rate of 6.6 L/min with 10.2 W input power. Case 2 was killed early due to the excessive growth of the calf, which caused functional obstruction of the inlet port. There was no blood clot inside the pump. During these periods, neither case exhibited any physiologic abnormalities. The PI 702 pump gives excellent results as a long-term implantable LVAD.     

Clinical experience for ventricular assist device

We began applying of our VAD system clinically in 1982 and have subsequently obtained good results. The first case treated with the VAD returned to normal life. In a total of 70 cases of clinical applications this system there has been instance of apparatus dysfunction. Confirming the reliability and safety promised by the results of biological experiments. Here, we report the results of clinical application of the system in a total of 61 cases between August, 1985 and March, 1989. The following conclusions were reached: 1) Satisfactory weaning and survival rates were obtained i.e. 18 cases out of 61 cases (30%) survived over one month and 13 cases (21%) are currently surviving, even in elderly patients of 60 years of age or older. 2) The weaning rate and survival rates were good after approximately 1 week of support. Detailed evaluation of the recovery of the heart and functions of other major organs has led to the conclusion that the results can be improved further when the weaning period is carefully determined. 3) With regard to surgical factors, good findings were obtained when the artificial heart-lung bypass time was less than 6 hours. The VAD can be used in the early stages without vainly attempting weaning from the artificial heart-lung bypass. 4) There were no mechanical problems with the hardware of the blood pump drive assembly, etc., or noteworthy side effects.     

Anesthetic implications for implantation of a left ventricular assist device: a case study

Restenosis after coronary angioplasty is a major limitation of an otherwise highly effective and safe procedure for the treatment of atherosclerotic coronary artery disease. Although the advent of coronary stenting has reduced restenosis rates for selected patients, an overall restenosis rate of 20% to 25% remains. Despite numerous trials, no effective pharmacologic therapy has been found. Intracoronary irradiation is a new technique proposed to prevent restenosis after angioplasty. In animal models of restenosis after balloon injury, there is marked reduction of neointimal proliferation when the injured vessel is irradiated, using a variety of radiation sources and delivery systems. Early human trials have underscored the importance of careful source calibration and dosimetry. A small, randomized, double-blind, placebo-controlled study of intracoronary irradiation to prevent recurrent restenosis recently reported striking reductions in angiographic restenosis as well as clinical event rates. A number of important issues remain unresolved, such as defining which component of the arterial wall serves as the target tissue for radiation, the minimal effective dose, the maximum tolerable dose, and user-friendly radiation delivery systems. Further studies are needed to define the safety, efficacy and the ultimate usefulness of intracoronary irradiation as an adjunct to current procedures in interventional cardiology.     

Adjunctive use of inhaled nitric oxide during implantation of a left ventricular assist device

Human erythrocyte protein phosphatase 2A, which comprises a 34-kDa catalytic C subunit, a 63-kDa regulatory A subunit and a 74-kDa regulatory B' (delta) subunit, was phosphorylated at serine residues of B' in vitro by cAMP-dependent protein kinase (A-kinase). In the presence and absence of 0.5 microM okadaic acid (OA), A-kinase gave maximal incorporation of 1.7 and 1.0 mol of phosphate per mol of B', respectively. The Km value of A-kinase for CAB' was 0.17 +/- 0.01 microM in the presence of OA. The major in vitro phosphorylation sites of B' were identified as Ser-60, -75 and -573 in the presence of OA, and Ser-75 and -573 in the absence of OA. Phosphorylation of B' did not dissociate B' from CA, and stimulated the molecular activity of CAB' toward phosphorylated H1 and H2B histones, 3.8- and 1.4-fold, respectively, but not toward phosphorylase a.     

Right ventricular infarction during left ventricular assist system support

Clinical and pathologic findings are presented of the first reported case in the English-language medical literature of pseudomesotheliomatous adenocarcinoma (PMA) occurring in an HIV-infected patient. PMA is an uncommon variant of peripheral lung cancer which typically occurs in elderly male patients. It mimics a malignant mesothelioma in terms of its clinical presentation and gross and microscopic appearance. The occurrence of this rare tumor in a young HIV-infected patient suggests some association between HIV infection and the development of PMA.     

Overcoming right ventricular failure with left ventricular assist devices

BACKGROUND: Right ventricular failure can lead to circulatory collapse while on left ventricular assist device support. By shunting blood from the femoral vein to the left ventricular assist device, cardiac output can be increased, but arterial oxygen saturation will decrease. METHODS: To determine the effects on O2 delivery, a model was developed on the basis of O2 uptake in the lungs and whole body O2 consumption. An equation was derived that related cardiac output, pulmonary venous O2 saturation, O2 consumption, and the ratio of shunt-to-systemic blood flow to systemic O2 delivery. RESULTS: When total cardiac output increases, the shunt will increase systemic O2 delivery while decreasing arterial O2 saturation and leaving systemic venous O2 saturation unaltered. When total output does not increase, the shunt will decrease systemic O2 delivery, arterial O2 saturation, and systemic venous O2 saturation. CONCLUSIONS: The analysis suggests that measuring systemic venous oxygen saturation may be a useful way to monitor patient safety. A decrease in systemic venous O2 saturation when creating the shunt implies an inadequate increase in cardiac output.     

First use of an untethered, vented electric left ventricular assist device for long-term support

This report describes the first long-term (505-day) application of the vented electric (VE) HeartMate left ventricular assist device (LVAD) (Thermo Cardiosystems, Inc). The device consists of an abdominally placed, battery-powered titanium blood pump that, in contrast to earlier pneumatically powered systems, allows patients untethered freedom of movement. The batteries last 5 to 8 hours and can be changed on a rotating basis indefinitely. The patient, a 33-year-old man (90 kg, blood type O) with idiopathic cardiomyopathy, experienced end-organ heart failure (New York Heart Association [NYHA] class IV) while he was awaiting heart transplantation. When his hemodynamic criteria met those outlined in the protocol, we implanted the VE-LVAD as a bridge to transplantation. The patient was supported by the device for more than 16 months. His cardiac status returned to NYHA class I, and he was eventually allowed to take day trips outside the hospital as he awaited transplantation. The VE-LVAD enabled the patient to participate in activities such as eating in restaurants, going to movies, and practicing basketball shots. Unfortunately, the patient died suddenly due to a neurological thromboembolic event that occurred on day 503 of VE-LVAD support. The VE-LVAD improved native left ventricular function by chronic unloading, and ventricular remodeling resulted in a more normal configuration anatomically, physiologically, and ultimately, histologically and pathologically.