PubMed · 8164239
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A S Russell. 1993. Exercise myoglobinuria.. https://pubmed.ncbi.nlm.nih.gov/8164239/
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Independently of phenomena related to rejection, atherosclerosis of the grafted heart or high blood pressure, there exists a qualitative and quantitative degradation of response to exercise in heart transplant recipients. Maximal oxygen consumption is generally reduced to 40 to 60% of normal levels. There are several interactive mechanisms. Paradoxically, the transplanted heart is a clear demonstration of the fact that several other elements are involved in the organisms response to exercise. Indeed, ventilation, exercise load, peripheral circulation, muscle metabolism and neurohormonal response also play a role. Vasoactivity of the peripheral arteries limits distribution and extraction of oxygen during exercise. Noradrenaline, renin, atrial natriuretic factor, vasopressin and endothelin levels are normal at rest, but an overreaction occurs during exercise. The percentage of type I (oxidative) fibres is reduced in muscles. Cyclosporine has also been shown to have a toxic effect on mitochondria in muscles. The deinnervated transplanted heart is thus called upon to work in coordination with peripheral elements which have also undergone alterations. Consequently, response to exercise cannot be significantly increased above the level reached before transplantation. Usually patients are not greatly hindered in their daily activities and rarely complain of breathlessness. Nevertheless, an improvement would be appreciated. A coherent physical rehabilitation programme can increase maximal oxygen consumption by 25 to 30% in these patients, essentially via improvement in peripheral anomalies. It is more difficult to modify cardiac response.
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Excision of large space occupying bullae in patients with emphysema is an accepted procedure if the underlying parenchyma is compressed and relatively normal. This operation may relieve symptoms of dyspnea and improve exercise tolerance. The volume reduction operation is based on different concept and designed for the diffuse type of emphysema. Resection of the most diseased lung in patients with marked hyperinflation may relieve thoracic distension and improve respiratory mechanics. We are currently evaluating prospectively the use of bilateral thoracoscopic volume reduction for patients with advanced, diffuse emphysema. During the last 1 1/2 years over 20 patients have been operated on. The average FEV1 was 765 ml/sec preoperatively and improved 40% within 3 months with a range of 0-100%. The 12 minute walking distance improved more than 100%. There was no perioperative mortality. Bilateral thoracoscopic volume reduction surgery is a palliative procedure but offers significant improvement in pulmonary function and exercise capacity for many patients.