Browsing by Subject "Heart - Surgery"

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    Closed mitral valvotomy in pregnancy
    (1989) Vosloo, S M; Reichart, B
    Heart disease remains the most important non-obstetric cause of maternal mortality and morbidity during pregnancy, despite its low incidence of less than 1%. This is due to the decline in the number of deaths from haemorrhage, infection and toxemia. In addition, a striking change in the pattern of proportional distribution of organic heart disease in pregnant women is being noted, with a decrease in chronic rheumatic lesions and an increase in congenital cardiac disease. In the Third World rheumatic mitral valve disease remains a most important condition during pregnancy. It is currently rarely seen in Europe and the United States. Mitral stenosis is the most commonly encountered rheumatic heart lesion that complicates pregnancy. The normal circulatory changes during pregnancy aggravate this lesion as the reduced, fixed valve area obstructs blood flow from the left atrium to the left ventricle, causing pulmonary congestion and oedema. Careful and regular follow up of these patients is essential, and surgery is indicated if optimal medical management fails. Cardiac surgery duting pregnancy represents a risk to both the foetus and the mother. For most procedures extracorporeal circulation and heparinization are necessary and adds to the · adverse effects of the operation. Closed mitral valvotomy, however, is an excellent low risk operative procedure in patients with tight mitral stenosis without causing undue harm to the foetus. Cuttler described the first attempted surgery of the mitral valve in 1923 and since then the procedure has been improved to benefit many patients with tight mitral stenosis. The first reports of closed mitral valvotomy during pregnancy were in 1952. Al though a more precise valvotomy can be obtained with an open procedure, the closed operation avoids the risks of extracorporeal circulation, particularly detrimental to the foetus. This report is a review of the Groote Schuur Hospital experience of patients with mitral stenosis requiring closed mitral valvotomy during pregnancy since 1965. The aims of the study are to analyse the outcome of the pregnancy, the effects of valvotomy during pregnancy on both the mother and the foetus, and the outcome regarding restenosis of the mitral valve.
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    Studies of the laser thermal probe in cardiovascular disease
    (1989) Rosenthal, Eric; Curry, Paul V L
    The initial use of optical fibres to transmit laser energy intravascularly was accompanied by a high rate of perforations and the production of inadequate vascular channels when used for recanalisation. The laser thermal probe - in which all laser energy is converted into heat by a metal cap at the tip of the fibre, prior to tissue application - was one of the earliest modifications designed to overcome these problems. The studies in this thesis were concerned with the application of the laser thermal probe to percutaneous peripheral and coronary artery angioplasty and His bundle ablation. In vitro studies were commenced in March 1987 when the first (argon) laser generator was installed in the cardiac catheterisation laboratory at Guy's Hospital and these were followed by clinical studies in three groups of patients: nine with peripheral artery occlusions, three with coronary artery stenoses and four with supraventricular arrhythmias using either argon or Nd-YAG energies. Suggestions that enhanced safety might be possible with on-line monitoring and/or control of the probe temperature were studied by recording the temperature responses in simulated circulations at flow rates observed clinically. The highly variable temperatures recorded in blood indicate that these measures are unlikely to contribute to improvements in either efficacy or clinical safety. An earlier report of successful peripheral artery recanalisation using the laser thermal probe was confirmed in the patients studied here, though a learning curve was evident. Coronary laser angioplasty had also been performed in a few patients with a similar device but without as much success. A more flexible "over the wire" laser probe was assessed here, first in cadaver coronary arteries and then in three patients undergoing coronary angioplasty. The lack of success seen with this laser thermal probe relates to the considerable differences found between peripheral and coronary arteries: percutaneous accessibility, vessel size and the susceptibility to thermal injury being the most important. These aspects and subsequent developments in coronary laser angioplasty are discussed further. The final chapter considers a hitherto new area for laser thermal probe application the interruption of arrhythmia circuits. Cadaver and electrophysiological studies indicated that ablation of the bundle of His might be possible with this device - without the need for a general anaesthetic. The course of the first patient ever to undergo this procedure is described, as well as the implications for percutaneous His bundle ablation using other energy sources.