Vasomotor wave and blood pressure response to erect posture after operation for aortic coarctation.

Low frequency fluctuations (five to 10/min) in blood pressure, that is vasomotor waves, were recorded in the erect position in 18 patients operated upon for an isolated aortic coarctation six to eight and a half years previously, and compared with vasomotor waves in six age matched normotensive controls with respect to frequency and amplitude. The investigation was carried out by simultaneous intra-arterial blood pressure radiotelemetry recordings from the brachial and femoral arteries in all but four of the controls. While the vasomotor wave frequency and blood pressure response to the erect posture was of the same order in the two groups, a highly significant difference was found with the amplitude of the vasomotor waves, being higher in the controls than in the patients. Furthermore, the results seem to indicate a negative correlation between age at the time of surgical repair and vasomotor wave activity (mmHg/min). It is suggested that the reduced vasmotor wave activity is brought about mainly by a disturbed input (from the baroreceptors) to the brainstem oscillator(s), caused by a combination of preoperative hypertension and prolonged exposure to high blood pressure.