Search PubMed⌕ Search

Biomedical subjects

W E Pae

Publications and source records attributed to W E Pae.

At least 37 records · Page 2Linked to original sources
PubMed1995

Linear end-systolic pressure-volume relationship during pulsatile left ventricular bypass represents native heart function.

This study assessed whether the end-systolic pressure-volume relationship obtained without any interventions during pulsatile left ventricular bypass adequately represents native heart function. In 11 anesthetized Holstein calves, left ventricular pressure was measured with a micromanometer while left ventricular volume was simultaneously calculated from orthogonal left ventricular diameters measured with ultrasonic dimension transducers. End-systolic pressure and volume data were subjected to linear regression analysis to achieve an end-systolic pressure-volume relationship. Data from both caval occlusions and aortic occlusion were used for the control end-systolic pressure-volume relationship (median r = 0.941, slope = 7.4 +/- 0.8 mm Hg per milliliter per 100 gm left ventricular weight; mean +/- standard error of the mean). During left atrial-aortic bypass with a Pierce-Donachy pneumatic assist pump in the asynchronous mode, the end-systolic pressure-volume relationships were obtained without interventions to change ventricular loading conditions. During maximal ventricular unloading during full to empty pumping, termed 100%, the resulting narrow range of pressure and volume data did not yield highly linear end-systolic pressure-volume relationships (median r = 0.669, slope = 4.9 +/- 0.9 mm Hg per milliliter per 100 gm left ventricular weight). However, at reduced rates off pumping, the end-systolic pressure-volume relationships were considerably linear (80%, median r = 0.819; 60%, median r = 0.868; 40%, median r = 0.899). Slopes did not significantly differ from control values (80%, 6.9 +/- 1.1; 60%, 8.2 +/- 1.1; 40%, 7.8 +/- 1.1). The end-systolic pressure-volume relationship obtained without exogenous load changes during asynchronous, pulsatile left ventricular bypass represents native left ventricular systolic function.

Animals↗
PubMed1995

Alternatives to human heart replacement.

The continuing and increasing discrepancy between the number of available donor hearts and the number of patients who might benefit from cardiac transplantation has prompted efforts in the development of xenotransplantation, mechanical assist devices, and cardiomyoplasty techniques. We briefly review recent work in these three fields. The results of experimental xenotransplantation between closely related species are improving slowly with currently available drugs, and clinical trials in this field may be possible in the near future. Implantable ventricular assist devices are also at a stage of development where permanent implantation is likely to be followed by a reasonable and worthwhile period of patient survival. With regard to cardiomyoplasty, steady progress is being made in clarifying exact indications and patient selection, as well as confirming the potential benefits.

Animals↗
PubMed1994

Left ventricular mechanics during synchronous left atrial-aortic bypass.

The purpose of this study was to analyze left ventricular mechanics during asynchronous, pulsatile left atrial-aortic bypass before and after microsphere injection with the pressure-volume relationship. In 14 anesthetized Holstein calves, left ventricular pressure was measured with a micromanometer and ultrasonic dimension transducers measured left ventricular orthogonal diameters. Ellipsoidal geometry was used to calculate simultaneous left ventricular volume. Contractility index, pressure-volume area, external work, and potential energy were calculated during steady-state contractions. These measurements were repeated during pulsatile left atrial-aortic bypass. To induce heart failure, we injected microspheres into the left main coronary artery, and the protocol for baseline and pulsatile left atrial-aortic bypass was repeated. Despite the significant differences in the baseline contractility index (7.4 +/- 0.7 mm Hg/ml versus 4.7 +/- 0.5 mm Hg/ml), contractility index remained the same during pulsatile left atrial-aortic bypass in control and heart failure modes, respectively. Pulsatile left atrial-aortic bypass significantly decreased end-diastolic volume (22% and 17%), pressure-volume area (58% and 48%) and external work (74% and 69%, all p < 0.05) during control and heart failure measurements, respectively. However, it did not change end-systolic volume or potential energy. In conclusion, asynchronous pulsatile left atrial-aortic bypass did not affect left ventricular contractile state in either the normal or failing heart. Although decreased pressure-volume area accounts for the reduction in myocardial oxygen consumption, unchanged potential energy suggested a limited unloading of the ventricle.

Animals↗
PubMed1993

Ventricular assist devices and total artificial hearts: a combined registry experience.

Data submitted voluntarily to the combined registry for the past 6 years on the use of ventricular assist devices for postcardiotomy cardiogenic shock in 965 patients and for circulatory support in conjunction with cardiac transplantation in 544 patients were analyzed. Of those patients whose ventricular function was expected to recover, approximately 45% were weaned from circulatory support and 25% were discharged from the hospital. Weaning status and hospital discharge were not different regardless of the type of original operative procedure or the pump design used. In the potential cardiac transplant group, 69% ultimately underwent transplantation and 66% were discharged from the hospital. The demographics (age and sex) of this group parallel those of patients undergoing isolated cardiac transplantation, and the 1- and 2-year survival estimates for patients requiring only univentricular support were equivalent to those of patients having isolated orthotopic cardiac transplantation. Ventricular assist devices are able to provide reasonable and safe circulatory support in both the postcardiotomy cardiogenic shock and the bridge-to-transplantation applications.

Cause of Death↗
PubMed1993

Heart transplantation for tumor.

Unresectable cardiac tumors, although unusual, are often rapidly fatal. A 31-year-old woman presented with a large tumor arising from the left ventricle and causing symptoms of a constrictive cardiomyopathy. After evaluation with echocardiography, angiography, and computed tomography, an exploration was carried out to confirm the extent of disease. Orthotopic heart transplantation was subsequently performed when a donor organ became available. She is now alive and disease-free 12 months after transplantation.

Adult↗
PubMed1993

A long-term ventricular assist system.

An implantable, electrically powered pump that will provide tether-free circulatory support is being developed. The blood pump consists of a seamless polyurethane sac within a polysulfone case. Björk-Shiley Monostrut valves provide unidirectional flow. The blood sac is compressed by a pusher plate with a stroke of 1.9 cm and actuated by a brushless direct-current electric motor and motion translator. The current unit is completely sealed, and inductive coupling techniques provide the electrical energy. The system has an implantable electronic control system as well as a battery that provides 30 minutes of operation when the external coil is disconnected. During normal operation, however, the pump is powered by a portable battery pack or by house current. The unit can pump 8.5 L/min at physiologic pressures. Twenty-six animals have had circulatory support for a period of more than 1 week. The average period of pumping was 62 days; the longest was nearly 8 months. Experiments were terminated in 18 animals because of pump-related problems and in 8 because of biologically related problems. Studies to date are very encouraging and suggest that, with further refinement, a reliable 2-year assist pump that will have important clinical application can be developed.

Animals↗
PubMed1992

Platelet and fibrinogen survival in calves implanted with artificial heart and ventricular assist device--correlation with autopsy findings.

The two main ingredients of blood clots formed on artificial surface are platelets and fibrinogen. In this study, we measured platelet and fibrinogen survival in calves implanted with total artificial heart (TAH) and left ventricular assist device (LVAD), and correlate these data with autopsy findings. Platelet survival with autologous 111In-labeled platelets was performed on nine calves implanted with TAH and five with LVAD. Fibrinogen survival with 131I-labeled homologous fibrinogen was performed on six calves with TAH and three with LVAD. Platelet survival was significantly shortened in both groups of animals: 5.89 +/- 0.52 days, control 6.46 +/- 0.31 days, p = 0.0013; fibrinogen survival was normal: 8.79 +/- 1.20 days, control 8.64 +/- 1.16 days. At autopsy two calves with TAH had multiorgan thromboembolism. Two other animals with TAH and four with LVAD had focal renal infarcts. Most animals had minor clot formation within the prosthetic device. Major septic complications occurred in four calves with TAH and one with LVAD. Continuous platelet activation by artificial surface probably explains the shortened platelet survival and thromboembolic complications.

Animals↗
PubMed1992

Development of malignant hyperthermia during mitral valve replacement.

Malignant hyperthermia is a genetically predisposed, potentially fatal disorder triggered by anesthetic agents. The early diagnosis and treatment of malignant hyperthermia is essential, yet often difficult, because the signs and symptoms of this disorder are not unique to the disease. When the patient is also undergoing cardiopulmonary bypass this disorder may be very difficult to recognize. In this article, we report a case of malignant hyperthermia diagnosed during mitral valve replacement and discuss the preoperative and postoperative management possibilities. The unusualness of this case stems from the fact that the patient had centronuclear myopathy. Although reported with other types of myopathies, centronuclear myopathy has rarely been associated with malignant hyperthermia. This episode of malignant hyperthermia was diagnosed by intraoperative measurements showing increased oxygen consumption despite hypothermic cardiopulmonary bypass.

Adult↗
PubMed1992

Hematologic and hemostatic complications associated with long-term use of total artificial heart: clinical and experimental observations.

The two most serious complications associated with long-term use of a total artificial heart (TAH) are thromboembolism and infection. In this article, we review our experience in one patient implanted with a pneumatic TAH for 396 days, and in 24 calves implanted with the same type of device for 70 to 353 (median 150) days. During his survival with the TAH, our patient suffered several thromboembolic episodes despite adequate anti-coagulation with warfarin. Autopsy showed widespread thrombotic lesions, mostly in the brain. Throughout his survival, the patient had markedly elevated plasma beta-thromboglobulin and fibrinopeptide A levels, indicating sustained activation of platelets and the coagulation system secondary to blood contact with the artificial surface. Long-term use of TAH in calves causes significant mechanical hemolytic anemia and a small reduction in the total leukocyte and neutrophil counts. The platelet count normalized to preimplantation levels by 25 to 35 weeks. At autopsy, thrombotic lesions and organ infarction were noted in 13 calves, and major septic complications were documented in 10 animals. Although impressive gains in the clinical and experimental use of TAH were achieved during the last 15 years, thromboembolism and infection remain challenging problems.

Anemia, Hemolytic↗
PubMed1992

Ventricular assist devices for postcardiotomy cardiogenic shock. A combined registry experience.

Data submitted voluntarily to the combined registry since its inception in 1985 to December 31, 1990, on the use of ventricular assist devices for postcardiotomy cardiogenic shock in 965 patients were analyzed. Approximately 45% of patients were weaned from temporary circulatory assistance and 24.6% reached hospital discharge regardless of the original operation. In 90% of patients who were discharged from the hospital, circulatory support was able to be discontinued by 1 week. Rates of weaning and discharge were statistically different and favored those patients requiring univentricular support only. Results were equal whether nonpulsatile centrifugal or pulsatile pneumatic devices were used for support. Although complications were frequent and multiple during assist pumping, patient variables including age greater than 70 years rather than direct complications caused by circulatory support were likely to affect overall outcome. In patients achieving hospital discharge, 2-year actuarial survival was 82% with 86% of patients being in New York Heart Association functional class I or II. In rare instances of device dependency in 43 patients (4.5%) with no contraindications to transplantation, 32 (74.4%) underwent bridge to cardiac transplant and 20 (62.5%) were discharged. This multi-institutional experience would continue to support the use of ventricular assist devices in postcardiotomy cardiogenic shock.

Adolescent↗
PubMed1991

Age-related changes in the efficacy of crystalloid cardioplegia.

Recent work has shown that multi-dose St. Thomas' Hospital cardioplegia solution (STHC) may not provide reliable protection of the neonatal myocardium. We have used an isolated working heart model to study the age-related development of this observation. Sets of eight hearts from 2-, 4-, 6-, and 8-week-old rabbits were subjected to 90 min of ischemia at 10 degrees C. STHC was infused at 30-min intervals in a dose of 10 ml/kg. There were no differences in the preservation of ATP stores during ischemia among the groups. The percentage recovery of preischemic mean aortic pressure, left atrial pressure, and heart rate were not different among groups, but the percentage recovery of aortic flow (AF) (expressed as means +/- standard error of the mean) was significantly lower in the 2- and 4-week hearts (44.1 +/- 8.2 and 66.2 +/- 7.7%) than in the 6- and 8-week hearts (93.0 +/- 6.4 and 97.6 +/- 4.7%). We have confirmed that the use of multi-dose STHC impairs recovery of ventricular function in the neonatal rabbit heart. This effect, however, diminishes rapidly as the immature animal develops and is not present by 6 weeks of age. Additional experimentation is necessary to identify those aspects of the developing myocardium that account for these observations.

Aging↗
PubMed1990

An electric artificial heart for clinical use.

Advances in microelectronics, high-strength magnets, and control system design now make replacement of the heart using an implantable, electrically powered pump feasible. The device described herein is a compact, dual pusher plate unit with valved polyurethane sac-type ventricles positioned at either end. The power unit consists of a small, brushless direct current motor and a motion translator. A microprocessor control system is used to regulate heart beat rate and provide left-right output balance. Bench studies lasting for as long as 1 year have been performed. Heart replacement with the electric heart has been performed in 18 calves since 1984. The longest survivor lived for more than 7 months. Among the causes of termination were component failure, thromboembolic complications, and bleeding. No major problem has been identified that precludes prolonged use of the electric heart. In the future the patient with end-stage heart disease will have an electric artificial heart as one therapeutic option.

Animals↗
PubMed1989

Mortality of coronary artery bypass grafting before and after the advent of angioplasty.

In an effort to determine whether the population of patients undergoing isolated coronary artery bypass grafting and the outcome of these operations have changed, we analyzed the records of two patient populations from our institution. Interventional cardiology techniques (angioplasty, thrombolysis) were not used at our institution before 1982. The records of 736 patients (group 1) who underwent isolated coronary artery bypass grafting from January 1975 to July 1981 were reviewed and compared with a group of 603 patients (group 2) who underwent operation from July 1985 to December 1987. The techniques of operation and myocardial preservation were virtually identical during the two periods. During the group 2 analysis period, 343 angioplasty procedures were performed. The patients in group 2 were significantly older, had increased preoperative New York Heart Association classification, had sustained more previous myocardial infarctions, and had more associated morbid medical conditions. There was a threefold increase in patients seen for reoperative revascularization procedures and a fourfold increase in emergency operations. Overall mortality, although not significantly different, did increase slightly from 2.69% in group 1 to 3.83% in group 2. Mortality after elective procedures remained essentially unchanged (2.05% for group 1 and 1.90% for group 2).

Aged↗