This study was undertaken to assess the value of dual chamber pacing in the treatment of vasovagal syncope. In a preliminary study, on two patients the time to presyncope during head-up tilt before and after implanting pacemakers was determined. Both patients fainted with similar decreases in blood pressure at almost exactly the same time after tilting. In the main study, nine patients with pacemakers implanted as treatment for syncope were studied, in random order, with pacemakers on and either off or turned to minimum rate. The pacemakers prevented bradycardia but had no effect on the time to syncope in a progressive test of head-up tilt followed by the addition of graded lower body suction. It is concluded that cardiac pacing does not prevent or even delay the onset of postural syncope and infer that bradycardia is an unimportant component of vasovagal attacks.

1. This study was undertaken to determine whether, in a group of patients complaining of recurrent syncopal attacks but with no apparent cause, there was evidence of abnormal cardiovascular reflex control. 2. The steady-state responses of blood pressure, heart rate and cardiac output to head-up tilting were determined in 67 patients using entirely 'non-invasive' methods. In some patients we also studied the immediate response of pulse interval to carotid baroreceptor stimulation by neck suction. 3. Two of the patients developed vasovagal attacks during the 20 min test period of head-up tilting. Eighteen others showed postural hypotension, defined as a fall in blood pressure to outside the limits of two SDS from the mean values of age-related control subjects. 4. Patients who showed postural hypotension had a mean fall in cardiac output significantly larger than that in age-related control subjects. Responses in the nonhypotensive patients did not differ significantly from controls. 5. Stimulation of carotid baroreceptors resulted in significantly smaller responses of pulse interval in the patients defined as having postural hypotension compared with the non-hypotensive patients and with the age-related control subjects. 6. In some of the patients who did not show postural hypotension during the standard test, the duration of tilt was prolonged for up to 1 h. Five out of 26 patients developed vasovagal attacks. All the vasovagal patients showed an initial tachycardia and the response of pulse interval to neck suction was significantly larger than in the controls.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of nisoldipine on renal function after 6 weeks treatment was investigated in hypertensive patients with and without renal impairment. Nisoldipine was well tolerated and an effective antihypertensive agent when administered over a period of 6 weeks. There were no significant changes in glomerular filtration, cardiac output, plasma renin activity or serum biochemistry during nisoldipine administration. Effective renal plasma flow was unaffected by treatment in the patients with normal renal function, but in the patients with renal insufficiency, the value decreased by a mean of 12%. Nisoldipine had no major untoward effects on renal function after 6 weeks administration, but minor changes in renal haemodynamics in the patients with renal insufficiency would suggest that careful monitoring of renal function is indicated in such patients.

1. Cardiovascular responses to upright tilting were determined before and after treatment with the calcium antagonist, nisoldipine, in patients with essential hypertension and in patients of similar ages and similar degrees of hypertension complicated by renal impairment. 2. Cardiac output was determined by a single breath respiratory method and heart rate and blood pressure by an automatic sphygmomanometer. 3. During placebo treatment, the supine values of heart rate and blood pressure were similar in the two groups, but the renal patients had significantly higher cardiac outputs. Following nisoldipine treatment blood pressure was lower in both groups due to decreased vascular resistance; cardiac output was unchanged. 4. Upright tilting lowered cardiac output in both groups, but the fall in the patients with renal disease was greater. There were similar increases in heart rate, diastolic blood pressure and vascular resistance in both groups. After nisoldipine, in the renal patients the fall in cardiac output was again greater and there was also a fall in systolic blood pressure. 5. These results indicate that patients with hypertension complicated by renal impairment may have reduced orthostatic tolerance particularly after treatment with nisoldipine.