Circadian blood pressure variation in morbidly obese hypertensive patients undergoing gastric bypass surgery

Abstract

Impaired blood pressure (BP) variation, often found in obesity and hypertension, is associated with increased cardiovascular risk. The effect of obesity surgery on BP variation is unknown. We performed this study to investigate the effect of gastric bypass surgery on circadian BP variation in morbidly obese hypertensive subjects. The study group consisted of eight patients (mean age 35.0 +/- 9.1 years), with impaired circadian BP rhythm. Controls were eight well-matched subjects (34.6 +/- 9.8 years) with normal BP rhythm. All patients underwent gastric bypass surgery. The 24-h ambulatory BP measurements were performed before (baseline) and 8 weeks after gastric bypass surgery. Mean body weight in the study group and controls decreased from baseline of 129.0 +/- 21.9 kg and 134.1 +/- 27.2 kg to 116.7 +/- 21.1 kg (by 9.5% +/- 2.1%) and 121.6 +/- 25.7 kg (by 9.3% +/- 1.7%) after the surgery, respectively (P < .0001 v baseline). Mean 24-h, daytime, and night-time BP values decreased significantly and similarly in both groups. In the study group mean 24-h systolic and diastolic BP decreased from 154.7 +/- 12.3 mm Hg and 105.6 +/- 8.1 mm Hg to 138.5 +/- 9.3 mm Hg and 90.8 +/- 6.7 mm Hg and in controls from 158.2 +/- 16.5 mm Hg and 106.2 +/- 10.0 mm Hg to 136.3 +/- 10.8 mm Hg and 92.9 +/- 6.3 mm Hg (P < .0001 v baseline), respectively. Circadian BP rhythm in the study group returned to the normal profile (mean systolic nocturnal fall increased from 4.0% +/- 2.4% to 16.4% +/- 4.0% and diastolic, from 5.1% +/- 3.0% to 17.3% +/- 5.5%; P < .0001 v baseline), whereas it remained normal in the controls. Surgery-induced body weight loss in morbidly obese hypertensive subjects with impaired circadian BP variation is not only associated with BP reduction, but also with the restoration of normal BP rhythm.