Ambulatory blood pressure and neuroendocrine control after diet-assisted gastric restrictive surgery

Obesity, Hypertension, and Bariatric Surgery

PURPOSE OF REVIEW

Obesity increases the risk of hypertension. However, blood pressure decreases before any significant loss of body weight after bariatric surgery. We review the mechanisms of the temporal dissociation between blood pressure and body weight after bariatric surgery.

RECENT FINDINGS

Restrictive and bypass bariatric surgery lower blood pressure and plasma leptin levels within days of the procedure in both hypertensive and normotensive morbidly obese patients. Rapidly decreasing plasma leptin levels and minimal loss of body weight point to reduced sympathetic nervous system activity as the underlying mechanism of rapid blood pressure decline after bariatric surgery. After the early rapid decline, blood pressure does not decrease further in patients who, while still obese, experience a steady loss of body weight for the subsequent 12 months. The divergent effects of bariatric surgery on blood pressure and body weight query the role of excess body weight in the pathobiology of the obesity phenotype of hypertension. The decrease in blood pressure after bariatric surgery is moderate and independent of body weight. The lack of temporal relationship between blood pressure reduction and loss of body weight for 12 months after sleeve gastrectomy questions the nature of the mechanisms underlying obesity-associated hypertension.

Changes in Central 24-h Ambulatory Blood Pressure and Hemodynamics 12 Months After Bariatric Surgery: the BARIHTA Study

BACKGROUND

Weight loss is associated to blood pressure (BP) reduction in obese patients. There is no information on central 24-h BP changes after bariatric surgery (BS).

METHODS AND RESULTS

In this study, we analyzed changes in 24-h BP 12 months following BS, with intermediate evaluations at 1, 3, and 6 months, in severely obese adults. The primary endpoint was aortic (central) 24-h systolic BP changes. Circadian BP patterns and hypertension resolution were also assessed. As secondary endpoints, we analyze changes in central 24-h diastolic BP as well as in all office and ambulatory peripheral BP parameters. Obese adults scheduled for BS as routine clinical care were recruited. We included 62 patients (39% with hypertension, 77% women, body mass index, 42.6 ± 5.5 kg/m²). Reduction in body weight was mean (IQR) 30.5% (26.2-34.4) 1 year after BS. Mean (95% CI) change in central 24-h systolic BP was - 3.1 mmHg (- 5.5 to - 0.7), p = 0.01 after adjustment for age, sex, and baseline hypertensive status. BP parameter changes were different between normotensives and hypertensives. Mean (95% CI) change in central 24-h systolic BP was - 5.2 mmHg (- 7.7 to - 2.7), p < 0.001, in normotensives and - 0.5 mmHg (- 5.1 to 4.0), p = 0.818, in hypertensives. There was a remission of hypertension in 48% of patients. Most patients had a reduced dipping pattern, similarly at baseline and 12 months after BS.

CONCLUSIONS

Among patients with severe obesity, there was a substantial central 24-h systolic BP decrease 12 months following BS. Importantly, this change was observed in those patients with normal BP at baseline.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT03115502.

Reduction of 24-h blood pressure variability in extreme obese patients 10 days and 6 months after bariatric surgery depending on pre-existing hypertension

Bariatric surgery is considered as a first line treatment in extreme obese patients to achieve a reduction in health risks. However, after surgical procedure obese patients with normal blood pressure (BP) levels still present residual risk, which may be partly related to lack of correction of BP profile and variability.

AIM

To evaluate short (10 days) and mid-term (6 months) changes of mean values, profile and variability of BP after bariatric surgery in extremely obese patients with and without hypertension.

MATERIALS & METHODS

A follow-up of cross-sectional study was conducted in 90 obese patients (aged 41.7 ± 11.3, BMI = 46.7 ± 5.7 kg/m2), who met the eligibility criteria and underwent bariatric surgery. Each patient underwent 24-h ambulatory BP monitoring with profile and variability estimation before, 10 days and 6 months after the intervention.

RESULTS

Sixty-seven (74.4%) patients had hypertension. Significant decrease from baseline in mean values of systolic and diastolic BP in 10 days (p < .005) and 6 months (p < .005) follow-up were observed only in patients with hypertension. Moreover, only hypertensive subjects revealed significant reduction (p < 0,05) from baseline in 24-h systolic and diastolic BP weighted standard deviation and average real variability after surgical procedure. No changes were found in dipping status.

CONCLUSIONS

Bariatric surgery not only decreased BP levels, but also contributed to reduction in BP variability in early period after intervention mainly in patients with pre-existing hypertension.

Long-term sympathoinhibitory effects of surgically induced weight loss in severe obese patients

Weight loss improves insulin sensitivity and exerts sympathomodulatory effects. No data, however, are available on the effects of the weight loss induced by vertical sleeve gastrectomy on sympathetic neural drive, insulin sensitivity, and their reciprocal cross talks. In 10 severe obese hypertensives (age, 54.0±2.3 years [mean±SEM]), we measured sphygmomanometric blood pressure, heart rate, body mass index, homeostatic model assessment index, plasma leptin, muscle sympathetic nerve traffic (microneurography), and baroreflex sensitivity (vasoactive drug technique). Measurements were performed 2 to 3 days before surgery and repeated 6 and 12 months after the procedure. Ten matched hypertensive obeses not undergoing gastrectomy served as controls. Six months after bariatric surgery, a significant (P<0.05) reduction in body mass index (-9.1±1.4 kg/m(2)), sphygmomanometric systolic blood pressure (-10.2±4.5 mm Hg), heart rate (-11.0±2.4 bpm), homeostatic model assessment index (-3-3±1.3 AU), plasma leptin (-53.6±8.8 μg/L), and muscle sympathetic nerve traffic (-15.0±3.4 bursts/100 heart beats) was observed. The weight loss, the plasma leptin reduction, and the sympathetic inhibition were maintained after 12 months, whereas homeostatic model assessment index showed a tendency to return toward presurgery values. A significant improvement in baroreflex control of sympathetic nerve traffic was observed both 6 (+32.1%; P<0.05) and 12 months (+60.7%; P<0.01) after gastrectomy. No significant changes in the above-mentioned variables were detected in the control group. These data provide evidence that massive weight loss induced by sleeve gastrectomy triggers profound sympathoinhibitory effects, associated with a stable and significant reduction in plasma leptin levels, whereas the improvement in insulin sensitivity was attenuated with time and unrelated to the sympathoinhibition.

Obesity, hypertension, and chronic kidney disease

Obesity is a major risk factor for essential hypertension, diabetes, and other comorbid conditions that contribute to development of chronic kidney disease. Obesity raises blood pressure by increasing renal tubular sodium reabsorption, impairing pressure natriuresis, and causing volume expansion via activation of the sympathetic nervous system and renin–angiotensin–aldosterone system and by physical compression of the kidneys, especially when there is increased visceral adiposity. Other factors such as inflammation, oxidative stress, and lipotoxicity may also contribute to obesity-mediated hypertension and renal dysfunction. Initially, obesity causes renal vasodilation and glomerular hyperfiltration, which act as compensatory mechanisms to maintain sodium balance despite increased tubular reabsorption. However, these compensations, along with increased arterial pressure and metabolic abnormalities, may ultimately lead to glomerular injury and initiate a slowly developing vicious cycle that exacerbates hypertension and worsens renal injury. Body weight reduction, via caloric restriction and increased physical activity, is an important first step for management of obesity, hypertension, and chronic kidney disease. However, this strategy may not be effective in producing long-term weight loss or in preventing cardiorenal and metabolic consequences in many obese patients. The majority of obese patients require medical therapy for obesity-associated hypertension, metabolic disorders, and renal disease, and morbidly obese patients may require surgical interventions to produce sustained weight loss.

The longer-term effects of Roux-en-Y gastric bypass surgery on sodium excretion

BACKGROUND

Obesity is an independent risk factor for hypertension and chronic kidney disease. During the first months after bariatric surgery, an improvement of sodium excretion has been described. The aim of this work was to study the influence of bariatric surgery on sodium excretion at more than a year after the intervention.

METHODS

Patients who have undergone Roux-en-Y gastric bypass (RYGB) and who had collected a 24-h urine sample before surgery more than 12 months ago were asked to participate. A second 24-h urine sample was collected. Blood pressure and weight were measured. The difference in sodium excretion before and after surgery was calculated, and the relationship with blood pressure and weight loss was investigated.

RESULTS

We included 33 patients; the median follow-up time was 21 months (range 14-41). Sodium excretion was high before surgery (median 195 mmol/day, IQR range 167-247) and decreased by 18 % after surgery (median 160 mmol/day, IQR range 118-205, p = 0.015), while there were significant improvements in body weight (% EWL 80.9 ± 21.8), systolic blood pressure (126 to 120 mmHg, p = 0.02), and diastolic blood pressure (84 to 77 mmHg, p = 0.002), even with a reduced number of antihypertensive drugs.

CONCLUSIONS

After RYGB and considerable weight loss, sodium excretion remains high in the longer term. The profound improvement in blood pressure cannot be explained by reductions in sodium excretion after RYGB.