PubMed Health⌕ Search

Biomedical subjects

W H Bain

Publications and source records attributed to W H Bain.

At least 55 records · Page 3Linked to original sources
PubMed1978

Comparative studies of pulsatile and nonpulsatile flow during cardiopulmonary bypass. III. Response of anterior pituitary gland to thyrotropin-releasing hormone.

Previous studies have indicated that, during nonpulsatile cardiopulmonary bypass, the anterior pituitary gland fails to respond to the tropic stimulus of thyrotropin-releasing hormone (TRH). This is in contrast to the normal response seen during closed cardiac and general surgical procedures. The Stöckert pulsatile pump system described in Part I has been employed in a comparative study of TRH responses in 20 patients subjected to pulsatile or nonpulsatile perfusion during open-heart surgery. In the nonpulsatile group, a consistently subnormal response to TRH injection was again found. In the pulsatile group, however, the pituitary response to TRH was normal in nine patients out of 10. The quantitative difference between the groups was statistically highly significant (p less than 0.005). These results indicate that the subnormal pituitary function seen with nonpulsatile bypass may be prevented by the use of pulsatile perfusion.

Adult↗
PubMed1978

Comparative studies of pulsatile and nonpulsatile flow during cardiopulmonary bypass. I. Pulsatile system employed and its hematologic effects.

A new, commercially available roller pump system able to deliver pulsatile and nonpulsatile flow has been studied in patients undergoing elective open-heart surgical procedures. The pulsatile pump (Stöckert Instrumente) may be used with standard extracorporeal circuit equipment and consistently produces a peripheral arterial pulse pressure of 25 to 30 mm. Hg at mean flow rates of 3.5 to 4.0 L. per minute. Twenty patients, arbitrarily allocated to pulsatile or nonpulsatile groups, have been studied. There were no significant differences between the groups in respect of age, weight, bypass time, pump flow, or mean arterial pressure during bypass. Comparative studies of the hematologic effects of pulsatile and nonpulsatile perfusion were carried out. There was no evidence of increased hemolysis with pulsatile flow, nor was there increased depletion of red blood cells (RBC's) or platelets in the pulsatile group. This pulsatile pump system may therefore be used to produce pulsatile perfusion during cardiopulmonary bypass without the fear of producing excessive blood cell trauma.

Adult↗
PubMed1978

Comparative studies of pulsatile and nonpulsatile flow during cardiopulmonary bypass. II. The effects on adrenal secretion of cortisol.

Previous studies have indicated that a significant reduction in plasma cortisol levels occurs during nonpulsatile cardiopulmonary bypass as a result of adrenocorticol hypofunction. The Stöckert pulsatile pump system described in Part I has been employed in a comparative study of plasma cortisol levels in 20 patients subjected to pulsatile or nonpulsatile perfusion during open-heart surgery. The plasma cortisol response pattern in the nonpulsatile group was identical to the pattern previously described, with no significant rise in cortisol levels during the period of perfusion. In the pulsatile group, however, plasma cortisol levels rose significantly during perfusion, reaching a mean level at the end of perfusion which was highly significantly greater than that in the nonpulsatile group (p less than 0.001). Correction of the plasma cortisol values for the effect of hemodilution was performed and, again, corrected cortisol values indicated a highly significant increase in end-bypass levels in the pulsatile groups (p less than 0.001). These results clearly indicate that the reduction in cortisol secretion during nonpulsatile bypass may be prevented by the use of pulsatile perfusion.

Adrenal Glands↗
PubMed1977

Radiographic appearances of implanted transvenous endocardial pacing electrodes.

It is important to ensure correct positioning of long-term pacing electrodes. Electrocardiograms and the radiographic appearance of pacing electrodes are conventionally used to confirm the site of the pacing electrode. Electrocardiographic patterns from stimulation of the right ventricle and left ventricle of the heart through the coronary venous system and the limitations in the interpretations of these patterns have been well documented in the past. The appearances of chest x-ray films can also be misleading. In the present study performed on cadavers, detailed appearances of pacing electrodes placed electively in different sites in the right ventricle and in the coronary sinus and its radicles are described, and the limitations in the interpretations of such appearances are discussed.

Coronary Angiography↗
PubMed1977

Blood filter evaluation.

Massive blood transfusion and extracorporeal circulation result in bombardment of the small pulmonary arterioles with micro-aggregates which are mainly composed of cellular degradation products, damaged platelets and leukocytes, fibrin strands, portions of cellular membrane and protein precipitates. Such amorphous material can cause patients to die of respiratory insufficiency without underlying chest trauma. Increasing amounts of stored blood are transfused to patients and extracorporeal circulation has become one of the most useful techniques for surgeons. Unfortunately, these procedures are often accompanied by disturbing post-operative consequences. This is because micro-aggregates invade the capillary network of several organs, especially lungs, kidneys, brain and retina. It is why blood filtration has recently gained added interest because of widespread efforts to minimise the number or emboli which are either transfused or reinfused to the patient through the blood return line.

Blood↗
PubMed1976

Experience in the development of low haemolysis pumps.

In an attempt to provide a pulsatile pump with a low rate of haemolysis, two pulsatile pumps have been developed. These were compared with commercially available pulsatile and roller pumps. The blood flow and the rate of haemolysis were studied under similar conditions. Our pumps were significantly better than the commercial pumps as far as mechanical damage to the red blood cells was concerned. However, we carried out certain modifications to one of our pumps which resulted in a significant reduction in the amount of haemolysis over its previous performance.

Heart-Lung Machine↗
PubMed1976

Mitral valve replacement in the presence of severe pulmonary hypertension.

Thirty patients with severe preoperative pulmonary hypertension (pulmonary artery pressure range 90-165 mmHg, mean 118 mmHg) were reviewed following single mitral valve replacement, with prosthetic valves, within the last 10 years (1964-74). The early and late mortality for this group was no different from that of the total series of mitral valve replacements performed over the same period. Marked postoperative clinical improvement was accompanied by corresponding radiological and electrocardiographic changes. In addition there was a statistically highly significant haemodynamic improvement in the 21 survivors (mean survival time 5 1/2 years). At recatheterization the mean pulmonary artery pressure was 41-5%, the mean wedge pressure 46-3%, and the transpulmonary gradient (PAm-LAm) 36-1% of the preoperative values. It is concluded that gross pulmonary hypertension is not per se a contraindication to mitral valve replacement surgery.

Adult↗
PubMed1976

Chylothorax: report of a case complicating ductus ligation through a median sternotomy, and review.

An unusual case of chylothorax is described in a 4-year-old child after repair of a ventricular septal defect and ligation of a patent ductus arteriosus through a median sternotomy. Left chylothorax developed after a latent period of six days and was treated initially with continuous drainage and parenteral supplementation of proteins and lipids. Operative intervention with oversewing of the site of the leak in the anterior mediastinum proved necessary after three weeks. The anatomical variations of the thoracic duct are outlined to explain the occurrence of chylothorax after diverse intrathoracic operations. The physiological effects of a thoracic duct fistula and various aspects of management are reviewed.

Child, Preschool↗
PubMed1976

The cortisol response during heart-lung bypass.

The response patterns of plasma cortisol and plasma free cortisol have been studied in 20 consecutive patients undergoing cardiac surgery involving the use of heart-lung bypass. Sixteen consecutive patients undergoing closed mitral valvotomy have been used as controls. Total plasma cortisol levels fell at the onset of extracorporeal circulation (ECC) and did not rise significantly throughout the period of ECC. The peak cortisol level in the bypass patients occurred at 24 hours postoperatively with elevated levels still present at 48 hours. This pattern was significantly different from the control patients (P less than 0.001) who exhibited the typical cortisol stress response pattern. Synthetic ACTH stimulation of the adrenal cortex during heart-lung bypass produced a positive response (i.e., a rise in plasma cortisol greater than 7.5 mug/100 ml) in all six patients studied while the six mitral valvotomy patients had no response to synthetic ACTH administration during operation (P less than 0.01). Plasma free cortisol estimations indicate that a rapid and significant rise in % free cortisol occurred at the onset of ECC, but that despite the rise in percentage free, the overall plasma free cortisol concentration (i.e., total plasma cortisol X % free) was significantly lower during ECC in the bypass patients when compared with control (P less than 0.01). Twenty-four hours postoperatively these concentrations were significantly higher in the bypass patients (P less than 0.001).

Cardiac Surgical Procedures↗
PubMed1976

Experimental evaluation of mechanical haemolysis with Starr-Edwards, Kay-Shiley and Björk-Shiley valves.

Mechanical cell damage was studied in vitro with three types of prostheses: Starr-Edwards, Kay-Shiley and Björk-Shiley valves. Mechanical cell damage was found to be closely related to the flow characteristics in the prosthesis. Considering valves of similar orifice diameter, Björk-Shiley valves produced the lowest rate of haemolysis. This is due to the improved haemodynamic characteristics of the valve which resulted from the laminar type of flow. With Starr-Edwards valves, smaller sizes produced unacceptably high rates of haemolysis. Increasing the mean forward flow across the valve resulted in a disproportionate rise in the energy loss and the rate of haemolysis when compared with Björk-Shiley valves of similar annulus diameters.

Blood Flow Velocity↗
PubMed1976

The effect of hemodilution on plasma levels of cortisol and free cortisol.

The effect of hemodilution on plasma levels of total cortisol and free cortisol was studied in 12 patients undergoing open-heart surgery. In each case, at the onset of extracorporeal circulation (ECC) the hematocrit value was rapidly reduced to 25 to 30 per cent and was maintained around this level during perfusion. Total plasma cortisol levels fell significantly with the hemodilution (p less than 0.0001), but the plasma concentration of free, biologically active cortisol was maintained at its pre-dilution level because of an increase in the percentage of plasma cortisol existing in the free form. There was a highly significant correlation between the degree of hemodilution and the percentage rise in the free cortisol fraction (r = 0.79; p less than 0.001). These results indicate the presence of a compensatory mechanism associated with cortisol binding which maintains the plasma level of free, biologically active cortisol when hemodilution has reduced the plasma level of total cortisol.

Adult↗
PubMed1975

Tricuspid valve replacement: a five-year appraisal.

Organic disease of the tricuspid valve required surgery in 18% of all patients undergoing valve replacement over a five-year period. Differentiation of organic from functional disease is difficult and may be made only at open-heart surgery. The results of a series of 56 patients who underwent tricuspid valve replacement are presented; of these, 53 had organic disease. Operative mortality at the end of five years had fallen to 7% with significant clinical improvement in 79% of patients, a reduction in cardiothoracic ratio in 81%, and a low incidence of postoperative tricuspid incompetence.

Female↗
PubMed1975

Early results of heart valve replacement with the Björk-Shiley prosthesis.

The operation on and subsequent course of 88 patients with valve replacements using Björk-Shiley tilting disc prostheses has been reviewed in terms of mortality, clinical results, and valve function. The follow-up period varied between 6 months and 2 years. The hospital mortality was 17% and late mortality 8%. Of those who left hospital, 75% returned to full normal activity and required less (or no) drug therapy other than maintenance anticoagulation. There was one transient embolic episode. Significant intravascular haemolysis does not occur with this prosthesis.

Adult↗