Objective-To assess immediate and medium term results of transcatheter laser valvotomy with balloon valvoplasty in selected infants with pulmonary atresia and intact ventricular septum.

No abstract

The differences in the pattern of the vasoactive hormone release in response to the stress of surgery and cardiopulmonary bypass (CPB) (pulsatile n = 15 and non pulsatile n = 23) were studied in the adult patients with mitral valve disease (MVD), aortic valve disease (AVD), and the coronary artery disease (CAD). A differential stimulation of the osmoreceptors, baroceptors, renin-angiotensin and the sympathetico-adrenal systems in these patients, resulted in the variations in the pattern of hormone release. Patients with MVD showed a greater stimulation of osmoreceptors, baroceptors and release of Arginine vasopressin (AVP). Renin-angiotensin system was more easily triggered in patients with AVD or CAD; and sympathetico-adrenal system in patients with CAD. The renin-angiotensin-aldosterone axis was better preserved in patients with CAD (r = 0.49, p less than 0.001) than in the patients with MVD (r = 0.38, p less than 0.02). Plasma renin release showed a significant correlation with noradrenaline release in the patients with MVD (r = 0.47, p less than 0.01); but this relationship was lost in the patients with the CAD, due to an excessive noradrenaline release. Pulsatile bypass reduced but did not abolish this response. Under unfavourable conditions, the stress response may persist in the early post-operative period.

The use of cardioplegia (pharmacologically induced electromechanical arrest) to achieve the ideal conditions for cardiac surgical operations was introduced over 20 years ago in clinical practice. Since then a number of ingredients have been added in various proportions to different cardioplegic solutions and their evaluation in experimental laboratories and clinical practice has continued. Any additive to a cardioplegic solution should be investigated in experimental laboratories and asanguinous cardioplegic solutions should be carefully formulated to avoid extremes of ionic concentrations, pH and osmolarity. Cold blood cardioplegia has not been found advantageous when compared with conventional asanguinous solutions. A combination of pharmacologically induced arrest with cold asanguinous cardioplegic solution and topical hypothermia protects the myocardium better than topical hypothermia alone or normothermic cardioplegia, and continuous infusion of cardioplcgic solutions has proved no better.than multidose administration. Multidose administration of cold eardioplegie solutions with moderate hypothermia and surface cooling has been found most satisfactory for prolonged aortic cross clamping (up to two hours). Use of cardioplegia in recent years has undoubtedly improved the prognosis of a number of patlents undergoing surgical correction of complex cardiac lesions.CARDIAC SURGICAL PROCEDURES often require a bloodless, relaxed and motionless field during operation, which is easily accomplished by ischaemic arrest induced by cross clamping the aorta. Any period of ischaemia is accomplished by metabolic and structural changes which determine the functional recovery of the heart in the postoperative period. The safe period of ischaemia for the human heart is not clearly defined but 20-30 minutes is generally considered the upper limit. When aortic cross clamping time exceeds this period substantial subendocardial necrosis may occur, with low output syndrome in the postoperative period. The need for protection of the myocardium during ischaemic arrest has been well recognized and a number of methods including local t and systemic hypothermia, 2 intermittent coronary perfusion) retrograde coronary perfusion with cold blood, 4 coronary perfusion with cold lactated Ringer's solution, s tetrodoxin, 6 acetylcholine,7 chemical asanguinous K + cardioplegia, s cold blood cardioplegia, 9 have been used in experimental studies and clinical practice. Of these, hypothermia and pharmacological arrest with cold cardioplegic solutions have now gained wide acceptance in clinical practice.Department of Anaesthesia and Cardiovascular Unit, Killingbeck Hospital, Leeds, England.Reprint requests to Dr. R.R. Chatrath, Consultant Anaesthetist, Killingbeck Hospital, Leeds, LS 14 6UQ, England.Canad. Anaesth. Soc. J., vol. 27, no. 4, July 1980 METHODS OF MYOCARDIAL PROTECTION Topical hypothermiaHypothermia has been proved to be an effective method of myocardial preservation. It provides a bloodless arrested heart, lowers the energy re...