Biomedical subjects

P Litwak

Publications and source records attributed to P Litwak.

7 recordsLinked to original sources

PubMed1979

Platelet turnover studies associated with left ventricular assist device (LVAD) implantation.

Calves given LVADs have been studied to determine changes in platelet turnover induced by the device and modified by time and anticoagulants. Passivation with time occurs but is surprisingly incomplete even one month later and despite coumadin, aspirin and dipyridamole. Without these drugs, enhanced platelet turnover and local thrombus formation on the device is exaggerated. Sequential platelet turnover studies may be useful to quantitate, monitor and/or predict thromboembolic events.

Animals↗

PubMed1979

A volume sensor for a pneumatically driven LVAD.

The volume sensor has proven to be a valuable tool in the operation and characterization of our pneumatically driven LVAD. It compensates for the decoupling between driver and LVAD that occurs in pneumatically actuated LVADs due to gas compressibility. Uses to which we have put the volume sensor represent only a small fraction of the potential applications. Additional uses contemplated include: Use as an alternate or backup for the R-wave detection network currently used to achieve synchronization with the natural heart. This could be done by starting the LVAD ejection phase when the filling flow rate drops below a given threshold, indicating that the left ventricle has finished filling the LVAD. Use for feedback for closed loop control of plate motion. Such control could reduce actuation delays without overdriving the LVAD. Use as a diagnostic tool to aid in the study of the LVAD and its interaction with the cardiovascular system. When used in conjunction with information on left ventricular, aortic, and drive pressures, it is possible to determine the resistance, inertia and compliant characteristics of the major elements of the LVAD and the vascular system to which it is joined.

Assisted Circulation↗

PubMed1978

Lumbar spondylectomy in the subhuman primate.

Removal of the 2nd or 3rd lumbar vertebrae (or both) has been accomplished in the subhuman primate (Macaca mulatta). Variations between this animal and the dog in posture, vertebral column anatomy, and spinal cord blood supply made no apparent difference in the results when compared with those in previous experiments. All macaques were able to clinb and to use their hind legs in a normal manner within 3 days after surgical operation. Once hair had regrown over the surgical incision, persons not familiar with the animals were not able to identify the animals that had undergone surgical operation. If a single vertebra was removed, use of spinous process and a single vertebral body plate was sufficient to stabilize the vertebral column. Except for 1 rhesus macaque whose spinous process plates were removed 20 days after the operation, vertebral columns of macaques (n = 3) that underwent single spondylectomy healed in nearly normal alignment. With the removal of 2 lumbar vertebrae, the previously described stabilization procedure was not sufficient to prevent kyphotic deformity of the vertebral column. Spinous process plates from 1 macaque were removed after 64 days. However, all these macaques (n = 3) could climb and use their legs as well as others in the colony.

Animals↗

PubMed1976

Aggressive pharmacologic and surgical treatment of spinal cord injuries in dogs and cats.

Aggressive pharmacologic and surgical treatment of spinal cord injuries in 22 dogs and 3 cats resulted in a recovery rate of 44% of all 25 animals. Excluding 5 animals that were euthanatized at surgery because of visualized cord transection and 5 that died during surgery because of secondary lesions, the recovery rate was 73%. This is compared with a recovery rate of 39% (7/18) for animals treated with more conservative methods at the same institution during an earlier period. Of the 7 animals without spinal cord transection and treated within 4 hours of injury, all recovered, pointing to the merits of early surgical intervention.

Aminocaproates↗

PubMed1976

Surgical preparation of miniature swine for atherosclerosis research.

A 2-stage surgical procedure for chronic intestinal, vascular, and lymphatic sampling in miniature swine is described. Cannulas were placed in the jejunum and ileum, followed by a 2nd implantation of indwelling catheters in the portal and hepatic veins, caudal vena cava, abdominal aorta, and cisterna chyli. The techniques used proved that miniature swine can be surgically adapted to meet experimental requirements.

Animals↗

PubMed1975

A vascular catheter-implanting device.

A catheter-implanting device (CID) was developed to aid in the placement of vascular catheters in blood vessels located deep in the body cavities, with minimal vascular damage or blood loss.

Animals↗

PubMedDate not supplied

Thoratec VAD system as a bridge to heart transplantation.

As of October 1988 the Thoratec ventricular assist device system was used in 72 heart transplant candidates at 20 medical centers in five countries. All patients were in imminent risk of dying before donor heart procurement, with a mean cardiac index of 1.6 +/- 0.5 L/min/m2 and a pulmonary capillary wedge pressure of 27 +/- 8 mm Hg, in spite of maximal medical therapy. The ventricular assist device system consists of a prosthetic ventricle (Pierce-Donachy design) with a 65 ml pumping chamber, made of Thoratec's BPS-215M polyurethane, appropriate cannulae for atrial or ventricular inflow and for arterial outflow connections, and a pneumatic drive console. The devices can be used for partial or complete support of the pulmonary and systemic circulations. Fifty-eight (81%) of the 72 patients received biventricular devices and 14 received support only on the left side of the heart. Average flow rate was 5.0 +/- 0.7 L/min on the left side and 4.3 +/- 0.7 on the right. Fifty-four patients (75%) recovered sufficiently to undergo heart transplantation after a median of 4.4 days (mean, 14.3 days; range, 8 hours to 81 days), and 45 of them have been discharged from the hospital (83% early posttransplant survival and 63% overall survival from implant to discharge). Of 14 patients supported for more than 30 days, 11 underwent heart transplantation, and nine were discharged alive. The actuarial 1- and 2-year posttransplant survival rates are 78% and 75%. We conclude that these heterotopic prosthetic devices provide an effective method of maintaining blood flow to vital organs until a donor heart can be procured.(ABSTRACT TRUNCATED AT 250 WORDS)

Actuarial Analysis↗