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Biomedical subjects

J Barak

Publications and source records attributed to J Barak.

13 recordsLinked to original sources
PubMed1989

In-vitro evaluation of a valveless cardiac-assist pump.

Diseases of the cardiovascular system are a major health-care problem. Nearly 50% of all deaths are due to cardiovascular disease. A number of cardiovascular patients experience heart failure, mostly of the left ventricle, and require some form of mechanical support. Cardiac-assist devices are used widely in the treatment of patients with damaged heart muscle. Cardiac-assist devices have been introduced recently to maintain circulation in heart failure patients, until a suitable heart transplant donor is found. Earlier types of left ventricular assist devices were the copulsation and the counterpulsation pumps, which increased the efficiency of the vascular system and decreased the workload on the failed heart. In this study, the authors investigated the performance of a valveless cardiac assist device that can be operated in copulsation, counterpulsation, or any intermediate mode with the left ventricle. The device has only one connection to the ascending aorta, no valves, and a common inlet/outlet. The authors measured the hemodynamic parameters in all modes and have suggested an optimal mode of operation in a left ventricular heart failure mode.

Heart Diseases↗
PubMed1989

Mechanical, biochemical, and structural effects of vitamin D deficiency on the chick heart.

The effects of vitamin D deprivation on the chick heart were investigated from three aspects: cardiac contractility (+/- dP/dT), intracellular high-energy phosphorus compounds, and structural differences. Four-week-old vitamin D-deficient chicks were divided into four groups: Group A served as the normal group and received subcutaneous injections of cholecalciferol; Groups B and C were vitamin D-deficient hearts but perfused differently; Group D received daily subcutaneous injections of 5 micrograms of 1,25(OH)2D3. When the isolated spontaneously beating hearts (modified Langendorff preparation) were perfused with Krebs-Henseleit (KH) solution containing a calcium concentration of 2.5mM, the myocardial contractility of the vitamin D-deficient hearts was significantly increased when compared with group A. After the isolated heart had beaten for one hour, the myocardial contractility in the vitamin D-deficient hearts was found to decline to significantly lower values. Presacrifice administration of 1,25(OH)2D3 improved cardiac performance. Vitamin D deficiency resulted in an enhanced rate of decline of the intracellular high-energy phosphorus compounds. No differences were found in the microscopic study. These observations suggest that vitamin D has a role in cardiac function.

Adenosine Triphosphate↗
PubMed1989

The effect of colloid osmotic pressure on the survival of sheep following cardiac surgery.

The occurrence of late complications in implanted cardiac prosthetic valves has emphasized the need for the development of an animal model in which these complications are reproducible. Sheep constitute an excellent model for chronical and pathological studies of prosthetic devices. In our experience, survival of sheep following implantation of prosthetic valves is closely related to postoperative serum colloid osmotic pressure (C.O.P.). The normal range as measured in 28 healthy sheep was 16.67 +/- 0.55 mm Hg. A protocol was developed to maintain the colloid hydrostatic pressure gradient (C.H.P.G.) as close as possible to the normal physiological range, and to delay the extubation until the C.O.P. was within this range, and the C.H.P.G. greater than 7 mm Hg. Using the above protocol, a new tri-leaflet polyurethane valve was inserted into eight, five to seven month old sheep in place of the mitral and tricuspidal valves. One hour after terminating the extacorporeal circuit, the C.O.P. was measured at 13.10 +/- 0.96; but within five to six hours, it rose to 17.1 +/- 1.1. During the same period, the C.H.P.G. increased from 3.02 +/- 0.96 to 7.6 +/- 0.50 mm Hg. The postoperative period was uneventful, and all animals survived. We have thus concluded that the routine measurement and monitoring of C.O.P. constitutes a guide of great clinical importance.

Animals↗
PubMed1988

Hidden loop jejunostomy--an experimental model.

A hidden loop jejunostomy, the placement of a proximal small bowel loop under the skin of dogs, is described. A feeding tube was inserted in the loop at a later date, which enabled feeding for at least 6 weeks. This procedure was well tolerated by the 10 dogs involved in this experimental model. It should be considered as a possible surgical procedure at initial explorative laparotomy in patients with advanced cancer originating at the gastric cardia or esophagogastric junction.

Animals↗
PubMed1984

Emergency mitral and aortic valve replacement during acute rheumatic fever in a 5-year-old child.

Emergency combined mitral and aortic valve replacement was performed during an attack of acute rheumatic fever in a 5-year-old boy. He made an uneventful recovery and has remained asymptomatic 1 year after the operation. From this and other authors' clinical experience, we believe that the decision to operate on these patients should be based on the severity of the disability and the hemodynamic disturbances rather than on the activity or inactivity of the rheumatic process.

Acute Disease↗
PubMed1980

Partial distal pancreatectomy with a hand-held CO2 laser. An experimental study.

Partial distal pancreatectomy was performed in dogs with CO2 laser. Results were compared with those obtained with use of diathermy and scalpel. Postoperative hyperamylasemia appeared in all the animals. The highest peaks in the laser and scalpel groups were found on the fifth postoperative day, after which they gradually returned to normal; the highest levels appeared in the diathermy group on the 21st day, and returned to normal only after 56 days. Pancreatography showed a sealed duct in the laser and diathermy groups although no duct ligation was performed. Histological study of the laser group disclosed initial thermal injury at the cut section with no damage to the nearby parenchyma, followed later by a smooth, thin scar. In the diathermy and scalpel groups, the injured zone became enlarged later by active parenchymal and interlobular inflammation in the underlying tissue.

Amylases↗
PubMedDate not supplied

Induction of controlled cardiac tamponade in the management of massive unexplained postcardiotomy bleeding. Case report and review of the literature.

Massive unexplained bleeding is a catastrophic complication of open heart surgery. The following paper describes a successful attempt to terminate such a hemorrhage by induction of controlled cardiac tamponade which caused augmentation of mediastinal pressure without hemodynamic decompensation, thereby aiding in hemostasis. This modality has not previously reported. Few events in clinical medicine are so ominous as the major unexplained hemorrhage. Diffuse bleeding from multiple transected small vessels may be controlled by mechanical techniques which apply pressure directly over the bleeding area. However, where the mediastinum is the source of bleeding, application of such a direct pressure with a closed chest, is both technically difficult and potentially risky. Reported attempts to stop bleeding by increasing the mediastinal pressure included the induction of pneumothorax, and the increase of positive end expiratory pressure (PEEP) has been published. To the best of our knowledge, a deliberate induction of controlled cardiac tamponade in order to terminate prolonged unexplained massive postcardiotomy hemorrhage has not been reported so far.

Aged↗
PubMedDate not supplied

Massive arterial air embolism during cardiopulmonary bypass.

Massive arterial air embolism occurred in two patients during 1250 open heart operations. Emergency measures led to complete recovery in both cases. Flow reversal, hypothermia and anti-oedema measures may be adequate in some clinical situations for total recovery after this catastrophic accident.

Cardiopulmonary Bypass↗