The impact of bariatric surgery on renal and cardiac functions in morbidly obese patients

Abstract

Background. Cardiac adaptation to obesity includes both structural and functional alterations in the heart. The kidneys also suffer the consequence of excessive increase of body weight. This study aims to assess the functional, cardiac and renal changes in a cohort of morbidly obese patients, as well as changes after bariatric surgery-the last therapeutic option for these patients. Methods. Patients referred for bariatric surgery were prospectively included. In each case, transthoracic echocardiography and a blood test were performed before the procedure and repeated 1 year after surgery. The estimation of the glomerular filtration rate (GFR) was addressed by the Cockroft-Gault lean body weight formula. Results. Sixty-one patients completed the 1-year followup. Of these, 81.9% were female. The mean age was 41.1 ± 9.8 years and the mean body mass index was 47.4 ± 5 kg/m 2 , decreasing to 30.5 ± 5.07 kg/m 2 after the procedure. Before surgery, the estimated GFR was 92.7 ± 25.4 mL/min, with hyperfiltration being present in 14.8% of patients, whereas an impaired GFR was detected in 8.3%. Patients showed preserved systolic function and cardiac remodelling. Diastolic function was abnormal in 27.9% of patients. At the 1-year follow-up, favourable changes in the left ventricular geometry and related haemodynamic status were observed. There was no significant change in the estimated GFR in the overall group, although hyperfiltration was ameliorated in 9.8% and a poor GFR was improved in 3.3.%. The improvement was not associated with changes in either blood pressure or the BMI. However, in this group of patients the amelioration of the GFR was associated with an increased stroke volume and improvement in diastolic function. Conclusions. In morbidly obese patients, GFR is usually normal and only a small percentage of them show hyperfiltration or a reduced GFR. Bariatric surgery has a favourable impact on renal function in only a reduced group of patients who also experience an improvement in cardiac performance.

Metabolic risk factors in nondiabetic adolescents with glomerular hyperfiltration

“…We used the bedside Schwartz equation derived from the Chronic Kidney Disease in Children (CKiD) study to calculate eGFR: eGFR (mL/min/1.73 m 2 ) ¼ 0.413 Â height (cm)/serum creatinine (mg/dL) [33][34][35]. Participants were classified as either having hyperfiltration (eGFR !120 mL/min/1.73 m 2 ) [36][37][38][39][40] or normal filtration (eGFR 90-120 mL/min/1.73 m 2 ). Participants with eGFR <90 mL/min/1.73 m 2 were excluded because of the potential for early CKD [4].…”

“…We designated eGFR >120 mL/min/1.73 m 2 as hyperfiltration for several reasons. This definition has been previously used as the threshold for hyperfiltration in other studies [36][37][38][39][40]58]. A recent study found glomerular hyperfiltration to be linked to cardiovascular risk factors in nondiabetic adults with the highest 20% of GFR [5].…”

Deleterious Effects of Increased Intra-Abdominal Pressure on Kidney Function

“…Such IAP is known to induce adverse renal effects as shown by us in experimental models of pneumoperitoneum [5,6]. Moreover, kidney function at both the renal hemodynamic level and proteinuria has been improved in morbidly obese patients who underwent bariatric surgery, a useful way of losing weight in these subjects [94][95][96]. The mechanisms underlying the beneficial renal effects of bariatric surgery in severely obese patients are not known; however it could be attributed to improvement in glucose metabolism, cardiac function, hypertension, and probably reduction of IAP following the surgical procedure.…”

Role of Bariatric Surgery in Chronic Kidney Disease Patients

“…Inoltre, a distanza di 1 anno, non si sono osservate riduzioni significative dell'eGFR nei vari gruppi di trattamento, sebbene si sia registrato un miglioramento dello stato di iperfiltrazione glomerulare passando dal 14.8% al 9.8% dei pazienti. La percentuale di pazienti con funzione renale compromessa (eGFR <60 mL/min) si è ridotta dall'8.3% al 3.3% dopo 1 anno di follow-up, dimostrando un netto miglioramento del filtrato glomerulare (47).…”