Unilateral Renal Artery Sympathetic Denervation May Reduce Blood Pressure in Patients With Resistant Hypertension

Abstract

A 29-year-old woman with essential resistant systemic hypertension for 17 years was referred for catheterbased renal sympatethic denervation (RSD). Despite optimal medical therapy including 9 different antihypertensive drugs (thiazides, angiotensin-converting enzyme inhibitors, calcium channel blockers, espironolactone, a-agonists, hidralazine, b-blockers, a-blockers, and amiloride), her mean blood pressure (BP) was 142/ 102 mm Hg (ambulatory BP monitoring measurement). The patient was hospitalized for 1 week before the procedure to exclude the diagnosis of pseudo-resistant hypertension. The benefits and complications were explained in detail before signing informed consent. Under conscious sedation, an 8F-long sheath was introduced into the right femoral artery and advanced to the aorta. Bilateral angiography revealed a left renal artery with a diameter of 5.2 mm and length of 10.9 mm and a right renal artery with a diameter of 5.1 mm and a length of 24 mm. A total of 5 lesions were circumferentially applied to the right renal artery with a distance of at least 5 mm between each lesion using an open-irrigated catheter. The duration of each lesion was 60 seconds. Satisfactory impedance drop was observed during each ablation point signifying appropriate tissue heating. At the end of the ablation, dye injection demonstrated signs of dissection most likely due to trauma caused by the long sheath at the ostia. A stent was immediately deployed with success and there were no apparent complications. Given that, in addition to unfavorable left renal artery anatomy, the decision was made to stop the procedure. The catheters were removed and manual compression was carried out. The patient was discharged 3 days later in stable condition and on 2 antihypertensive drugs. At 1-month follow-up, one more antihypertensive agent was added to the therapy (BP = 146/106 mm Hg). Ambulatory BP monitoring at 3 months demonstrated a mean BP of 133/ 82 mm Hg. At 6 months, the patient was still taking 3 medications, and mean BP was 132/78 mm Hg (Table). Renal angiography at 6 months revealed patent stent and no renal artery abnormalities. DISCUSSION This unique case suggests that unilateral catheter-based RSD may reduce BP in patients with resistant hypertension. Radiofrequency catheter ablation has been used for the treatment of cardiac arrhythmias for several decades. Recent studies have shown benefits of catheterbased RSD as an alternative strategy for BP control in patients with resistant chronic hypertension. Lesion formation depends on several factors such as proper electrode-tissue contact, power and duration applied, and type of catheter used, among others. In several clinical settings such as left ventricular tachycardia ablation, it is crucial to generate lesions deeply enough to penetrate into the myocardial tissue. However, excessive electrode tip temperature may lead to coagulum and char formation, which limits power delivery. That being said, many efforts have been undertaken in order to optimize power delivery into the myocardial tissue without exceeding electrode tip temperature. Irrigation of the catheter tip has been developed and is now a well-established method to enhance the depth of tissue penetration of radiofrequency energy without causing excessive electrode tip temperature, and therefore enlarging lesion size. Considering the location of the renal nerves deep into the adventitia, we hypothesized that the use of irrigated catheters could be more beneficial than solid-tip catheters in this setting. This could explain the better results observed in this case compared with previous published data. 1 On the other hand, our results are consistent with the publication of Ahmed and colleagues in which 10 patients with resistant hypertension underwent bilateral RSD with a saline-irrigated radiofrequency catheter. The authors showed reduction in the systolic/diastolic blood pressure of 21/11 mm Hg. 2 Large studies, however, need to be performed to demonstrate consistent benefit.