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Obesity is associated with significant increases in arterial blood pressure, heart rate, and glomerular filtration rate (GFR). Previous studies have shown that obesity-induced hypertension is due, in part, to increased renal sympathetic activity which causes sodium and water retention. Recently, catheter-based renal denervation (RD) has been reported to lower arterial blood pressure in humans with ‘resistant’ hypertension. The current study was designed to test if RD lowers arterial blood pressure in obese, hypertensive canines. Obesity hypertension was created in mongrel hounds by feeding them a high fat diet for five weeks. Blood pressure and heart rate were measured 24-hours per day using arterial catheters and GFR with 125I-iothalamate clearance. After two weeks of control (Con) measurements, bilateral RD was performed in nine canines by radiofrequency ablation from within the renal arteries using the St. Jude Medical EnligHTNTM renal denervation system. Following RD, blood pressure was measured continuously for eight weeks and GFR was measured bi-weekly for six weeks. At the end of the eight-week period, both left and right renal arteries were collected for histological analysis, and kidney samples were obtained for renal catecholamine evaluation. Mean arterial pressure decreased from 109 ± 2 mmHg in the Con period to 99 ± 2 mmHg after RD (p<0.01). The largest change was seen in systolic blood pressure which fell from 157 ± 5 mmHg during the Con period to 132 ±2 mmHg after RD ( p<0.01). RD lowered diastolic blood pressure from 89 ± 2 mmHg to 85 ± 2 mmHg (p<0.01). There were no significant changes in heart rate (Con 96 ± 3 vs. RD 103 ± 6 beats per minute) or GFR (Con 90.5 ± 5.3 vs. RD 90.3 ± 3.6 mL/min). RD caused injury in at least 42% of the renal nerves observed and reduced renal tissue catecholamine by 47% (p<0.01). Histological examination of the renal arteries revealed minor endothelial and medial fibrosis in areas of the lesions and no signs of renal arterial stenosis were observed. Thus, catheter-based renal denervation lowers blood pressure in obese canines without compromising renal function or vascular integrity.
- 2013 American College of Cardiology Foundation