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Biomedical subjects

W Dembitsky

Publications and source records attributed to W Dembitsky.

11 recordsLinked to original sources
PubMed2001

Long-term use of a left ventricular assist device for end-stage heart failure.

BACKGROUND: Implantable left ventricular assist devices have benefited patients with end-stage heart failure as a bridge to cardiac transplantation, but their long-term use for the purpose of enhancing survival and the quality of life has not been evaluated. METHODS: We randomly assigned 129 patients with end-stage heart failure who were ineligible for cardiac transplantation to receive a left ventricular assist device (68 patients) or optimal medical management (61). All patients had symptoms of New York Heart Association class IV heart failure. RESULTS: Kaplan-Meier survival analysis showed a reduction of 48 percent in the risk of death from any cause in the group that received left ventricular assist devices as compared with the medical-therapy group (relative risk, 0.52; 95 percent confidence interval, 0.34 to 0.78; P=0.001). The rates of survival at one year were 52 percent in the device group and 25 percent in the medical-therapy group (P=0.002), and the rates at two years were 23 percent and 8 percent (P=0.09), respectively. The frequency of serious adverse events in the device group was 2.35 (95 percent confidence interval, 1.86 to 2.95) times that in the medical-therapy group, with a predominance of infection, bleeding, and malfunction of the device. The quality of life was significantly improved at one year in the device group. CONCLUSIONS: The use of a left ventricular assist device in patients with advanced heart failure resulted in a clinically meaningful survival benefit and an improved quality of life. A left ventricular assist device is an acceptable alternative therapy in selected patients who are not candidates for cardiac transplantation.

Activities of Daily Living↗
PubMed2001

Multicenter clinical evaluation of the HeartMate vented electric left ventricular assist system in patients awaiting heart transplantation.

BACKGROUND: Despite advances in heart transplantation and mechanical circulatory support, mortality among transplant candidates remains high. Better ways are needed to ensure the survival of transplant candidates both inside and outside the hospital. METHODS: In a prospective, multicenter clinical trial conducted at 24 centers in the United States, 280 transplant candidates (232 men, 48 women; median age, 55 years; range, 11-72 years) unresponsive to inotropic drugs, intra-aortic balloon counterpulsation, or both, were treated with the HeartMate Vented Electric Left Ventricular Assist System (VE LVAS). A cohort of 48 patients (40 men, 8 women; median age, 50 years; range, 21-67 years) not supported with an LVAS served as a historical control group. Outcomes were measured in terms of laboratory data (hemodynamic, hematologic, and biochemical), adverse events, New York Heart Association functional class, and survival. RESULTS: The VE LVAS-treated and non-VE LVAS-treated (control) groups were similar in terms of age, sex, and distribution of patients by diagnosis (ischemic cardiomyopathy, idiopathic cardiomyopathy, and subacute myocardial infarction). VE LVAS support lasted an average of 112 days (range, < 1-691 days), with 54 patients supported for > 180 days. Mean VE LVAS flow (expressed as pump index) throughout support was 2.8 L x min(-1) x m(-2). Median total bilirubin values decreased from 1.2 mg/dL at baseline to 0.7 mg/dL (P =.0001); median creatinine values decreased from 1.5 mg/dL at baseline to 1.1 mg/dL (P =.0001). VE LVAS-related adverse events included bleeding in 31 patients (11%), infection in 113 (40%), neurologic dysfunction in 14 (5%), and thromboembolic events in 17 (6%). A total of 160 (58%) patients were enrolled in a hospital release program. Twenty-nine percent of the VE LVAS-treated patients (82/280) died before receiving a transplant, compared with 67% of controls (32/48) (P <.001). Conversely, 71% of the VE LVAS-treated patients (198/280) survived: 67% (188/280) ultimately received a heart transplant, and 4% (10/280) had the device removed electively. One-year post-transplant survival of VE LVAS-treated patients was significantly better than that of controls (84% [158/188] vs 63% [10/16]; log rank analysis P =.0197). CONCLUSION: The HeartMate VE LVAS provides adequate hemodynamic support, has an acceptably low incidence of adverse effects, and improves survival in heart transplant candidates both inside and outside the hospital. The studies of the HeartMate LVAS (both pneumatic and electric) for Food and Drug Administration approval are the only studies with a valid control group to show a survival benefit for cardiac transplantation.

Cohort Studies↗
PubMed1999

CardioWest total artificial heart: a retrospective controlled study.

The CardioWest total artificial heart (TAH) is a pneumatic device that is used as a bridge to heart transplantation and the only TAH available that totally replaces the failing ventricles. It has been utilized in selected centers in the U.S.A. with approval from the Food and Drug Administration. Strict criteria have been developed to select candidates to be bridged with the TAH. The patient must be a heart transplant candidate of age >18 and <59 years with a body surface area (BSA) > or = 1.7 m2, cardiac index (CI) <2.0 L/min/m2, and 2 inotropic agents or 1 plus an intraaortic balloon pump (IABP). A total of 24 heat transplant candidates (Group A) met the entry criteria and underwent placement of the TAH between January 1993 and July 1996. Group A consisted of 23 males; 16 patients had an IABP. The control group (Group B) consisted of 18 heart transplant candidates who met the TAH entry criteria but never received a TAH. Group B consisted of 15 males; 14 patients had an IABP. Preimplantation pulmonary vascular resistance (PVR) (Wood units), serum creatinine (mg/dl), and total bilirubin (mg/dl) were determined in both groups. The mean values for Groups A and B were, respectively, age: 47 and 47 years, BSA: 2.01 and 1.93 m2, CI: 1.5 and 1.8 L/min/m2, PVR: 2.88 and 2.47 Wood units, creatinine: 1.5 and 1.6 mg/dl, and bilirubin: 1.8 and 1.4 mg/dl. In Group A, 1 patient died on the TAH, 1 patient died after transplant, and 22 patients reached transplant and were discharged home for a survival rate of 91.7%. In Group B, 10 patients died while waiting for a heart transplant. Of the 8 patients transplanted, 7 survived and were discharged home for a survival rate of 38.9% (p = 0.0003). In summary the CardioWest TAH provided an excellent and successful method of bridging patients to heart transplantation with a reasonable risk.

Female↗
PubMed1997

International experience with the CardioWest total artificial heart as a bridge to heart transplantation.

As the number of potential heart donors remains constant and the number of potential recipients continuous to increase, the need for circulatory devices to bridge patients becomes more important. The CardioWest total artificial heart (TAH) is a pneumatic, implantable system that totally replaces the failing ventricles. It has been utilized worldwide as a bridge to heart transplantation in 79 patients. There were 73 males and six females who received the TAH. Currently three patients remain on the device waiting for transplantation. A total of 55 patients (70%) were transplanted of which 50 survived (91% of patients transplanted) and were discharged home. Idiopathic/dilated cardiomyopathy was the most common etiology followed by ischemic cardiomyopathy. The mean duration of implant was 34 days (range 0-186 days) and the mean age of the group was 45 years (range 16-62 years). Twenty-one patients died while on the device. Multiple organ failure was the major cause of death. There were a total of 255 complications in this group that included reoperation, bleeding, hepatic failure, renal failure, respiratory failure, neurologic events, thromboembolic events, infections, device malfunction, and fit complications. This represented a mean complication rate of three events per patient. The survival rate for the CardioWest TAH of 91% of the patients who reached transplantation is an improvement over that of the Symbion registry (55% of those transplanted) probably as a result of a better patient selection and better control of the coagulation system. These results are also comparable to those survival results obtained with other biventricular and left ventricular assist devices currently available.

Adolescent↗
PubMed1992

Prolonged extracorporeal support for ARDS using surface-heparinized equipment.

Severely ill ARDS patients present major supportive challenges when conventional ventilatory support is failing. A patient is described who was treated with venovenous extracorporeal lung support for 28 days, using surface-heparinized circuitry. Her recovery illustrates the potential for salvage of near-terminal ARDS patients when complications of support can be minimized.

Adult↗
PubMed1987

Thromboendarterectomy for chronic, major-vessel thromboembolic pulmonary hypertension. Immediate and long-term results in 42 patients.

Since 1970, forty-two patients with pulmonary hypertension due to chronic, thromboembolic obstruction of the major pulmonary arteries have had pulmonary thromboendarterectomy at the University of California, San Diego, and the San Diego Veterans Medical Centers. Duration of symptoms before admission averaged 4.4 years, with many alternative diagnoses having been made. At admission, 29 patients had class IV disease by New York Heart Association criteria, and 12, class III. Immediately after surgery, pulmonary vascular resistance declined significantly (p less than 0.001) from 897 +/- 352 dynes/s.cm-5 to 278 +/- 135 dynes/s.cm-5. Seven patients with class IV disease died in the postoperative period. Of the 35 survivors (mean follow-up, 28 months), 16 had class I disease; 18, class II; and 1, class III. Of the 17 patients who have returned for cardiac catheterization at 4 to 12 months after surgery, a further decline (p less than 0.05) in pulmonary vascular resistance has occurred. This experience indicates that the disorder is commoner than we previously suspected and that thromboendarterectomy is feasible, even in patients with severe and protracted hemodynamic compromise.

Adult↗
PubMed1979

The importance of hyperkalemia in a cold perfusion solution: a correlative study examining myocardial function, metabolism, tissue gases, and substrates.

Twenty-four pigs were studied to assess the effect of potassium in a cardioplegic solution on the ability of the swine myocardium to maintain functional and metabolic integrity following induced ischemia. The pigs were evaluated on total and right heart bypass with measurement at normothermia and after a one-hour intervention of stroke volume (SV), coronary blood flow (CBF), myocardial oxygen consumption (MVO2), and lactate extraction. Myocardial tissue gases (PmO2 and PmCO2) were continuously monitored and, at the conclusion of the procedure tissues were analyzed for adenosine triphosphate (ATP). There were five interventions: (1) hypothermic perfusion (28 degrees C) (Group 1); (2) hypothermic ischemia (28 degrees C) (Group 2); and hypothermic ischemia with a cardioplegic solution (nonlactated Ringer's solution, pH 7.4, 4 degrees C) using (3) normokalemia (4 mEq of potassium chloride/L, 300 mOsm/L (Group 3), (4) hyperkalemia (43 mEq of KCl/L, 390 mOsm/L) (Group 4), and (5) normokalemia with increased osmolarity (3.6 mEq of KCl/L, 400 mOsm/L) (Groups 5). A significant decrease in SV and elevation in peak PmCO2 were seen in all groups subjected to ischemia except those protected with hyperkalemic solution. We conclude that the presence of hyperkalemia in a cold root perfusion solution provides better myocardial protection than cold root perfusion alone. Furthermore, potassium arrest appears to be more protective than coronary perfusion at 28 degrees C.

Animals↗
PubMedDate not supplied

Effect of LVAD outflow conduit insertion angle on flow through the native aorta.

BACKGROUND AND AIM: The goal of this study was to evaluate the effect of surgical anastomosis configuration of the aortic outflow conduit (AOC) from a continuous flow left ventricular assist device (LVAD) on the flow fields in the aorta using CFD simulations. The geometry of the surgical integration of the LVAD is an important factor in the flow pattern that develops both in series (aortic valve closed, all flow through LVAD) and in parallel (heart pumping in addition to LVAD). METHODS: CFD models of the AOC junctions simulate geometry as cylindrical tubes that intersect at angles ranging from 30 degrees to 90 degrees. Velocity fields are computed over a range of cardiac output for both series and parallel flow. RESULTS: Our results demonstrate that the flow patterns are significantly affected by the angle of insertion of the AOC into the native aorta, both during series and parallel flow conditions. Zones of flow recirculation and high shear stress on the aortic wall can be observed at the highest angle, gradually decreasing in size until disappearing at the lowest angle of 30 degrees. The highest velocity and shear stress values were associated with series flow. CONCLUSIONS: The results suggest that connecting the LVAD outflow conduit to the proximal aorta at a shallower angle produces fewer secondary flow patterns in the native cardiovascular system.

Anastomosis, Surgical↗
PubMedDate not supplied

Infections with the CardioWest total artificial heart.

The CardioWest total artificial heart is a pneumatically driven device that totally replaces the failing ventricles. It is currently used as a bridge to heart transplantation in selected centers in the United States under a study by the Food and Drug Administration. Twenty-seven patients have undergone placement of the total artificial heart since 1993 with the intention to bridge to transplantation. Inclusion criteria included candidacy for heart transplantation, cardiac index (CI) < 2.0 L/min/m2, and maximal inotropic support. The population consisted of 25 men and 2 women of mean +/- SD age 46.5 +/- 10.3 years, body surface area 2.01 +/- 0.17 m2, and duration of implant 52 +/- 42 days. Initial diagnosis included ischemic cardiomyopathy (n = 10), idiopathic (n = 10), viral (n = 4), valvular (n = 2), and graft failure (n = 1). Infectious complications were defined as systemic (evidence of leukocytosis or fever) or local. The population experienced 64 infections (range, 0-9 per patient): 45 systemic and 19 local. Three patients did not experience any infection. Twenty-five patients reached transplantation, and were discharged home for a survival rate of 92.6%. Two patients died during the bridge, one because of mechanical failure, and one because of infection (mediastinitis). Therefore, death attributable to infections occurred in 3.7%. Previous reports of the total artificial heart experience in the late 1980s described death rates as high as 40%. Although infectious complications are common in patients who are bridged to heart transplantation with the total artificial heart, mortality from infections is 10 times less than previously reported. This may be the result of a better strategy for bridging to transplantation that includes patient selection, mobilization, early central line removal, and waiting until all possible infections are resolved before proceeding to transplantation.

Female↗