Browsing by Author "Reichart, B"

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    Adenosine and its role in cardioplegia : experimental evaluation in the isolated rat heart and in an-vivo primate model
    (1997) Boehm, Dieter Hermann; Opie, Lionel H; Reichart, B
    This study was designed to investigate the role of adenosine, an endogenous cardioprotectant agent, without high potassium and as cardioplegic additive to high potassium solutions. Adenosine cardioplegia and potassium cardioplegia supplemented by adenosine (K + ADO) were investigated in terms of hemodynamic, metabolic and ultrastructural recovery in the isolated rat heart and in the in-vivo baboon model during periods of global myocardial ischemia, simulating the clinical situation during open heart surgery. The results obtained in both models show that adenosine improved postischemic hemodynamic function when used without high potassium cardioplegia. The combination of adenosine and high potassium was less effective in both models in terms of hemodynamic recovery; however, improved rhythm stability and coronary vasodilatation were still present. In addition adenosine alone was able to induce fast electromechanical arrest in the isolated rat heart. However, failure of even high concentrations of adenosine to limit ventricular fibrillation in the baboon exclude its use as cardioplegic agent on its own without additional interventions. It appears likely that adenosine without high potassium is cardioprotective via activation of A₁ receptors and opening of ATP-sensitive potassium channels, a mechanism which is probably non-functional in a high potassium environment. In view of the limited cardioprotection achieved with the combination of adenosine and high potassium further studies should aim for additional interventions to induce cardioplegia with adenosine and normokalemic solutions.
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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.