Coarctation of the aorta. A long-term follow-up study after surgery.

Coarctation of the aorta is characterized by a high blood pressure in the upper part of the body and a decreased blood pressure in the lower part. Without surgery it leads to an increased mortality from hypertensive manifestations. However, even after surgery 20--25 per cent of these patients are reported to have a persistent hypertension. Moreover, an increased cardiovascular mortality has been reported. The aim of the present investigations was to study the long-term results after coarctectomy with special emphasis on reactions to hard muscular work and to study some of the possible mechanisms behind this persistent hypertension. Nineteen men aged 16--28 years, operated upon for coarctation of the aorta at an average age of 10 years (range 6--16 years), were investigated 10--11 years after surgery with respect to cardiac and pulmonary function, the state of the vessels and muscle metabolism. Lung function and the intrapulmonary gas exchange were normal, as was the maximal aerobic work capacity. Cardiac output and stroke volume and the arterio-venous oxygen difference were also normal, even during maximal exercise. More than half of the group had a systolic hypertension, both at rest and during exercise, in the upper part of the body, while the diastolic pressure was generally normal. A systolic blood-pressure gradient between the arm and the leg was observed and its was increased during exercise. Corresponding differences in the mean and diastolic pressures were also found during exercise. An increased muscle-lactate concentration in the leg and an increased muscle/blood lactate quotient during exercise indicated a somewhat impaired blood-flow to the leg muscle. The systemic vascular resistance in the right hand during maximal vasodilation was increased much more than the blood-presssure elevation indicated, while the baroreflex sensitivity was adequate. The findings favour early operation for coarctation of the aorta and indicate the necessity of thorough, and probably lifelong, follow-up of these patients. Moreover, blood pressure, either measured at rest or measured during exercise, cannot be used as a measure of the anatomical result after surgery. Key-words: Baroreflex sensitivity, cardiac output, coarctatio aorte, exercise test, hypertension, intra-arterial blood pressure, lung volumes, muscle metabolism, oxygen uptake, peripheral resistance, pulmonary gas exchange.