Preliminary results of the human clinical trial SOUND-ITV: ultrasound mediated interventional treatment of resistent hypertension

Abstract

Purpose: Recent clinical evaluations confirmed positive results of renal denervation, a catheter based procedure that utilizes radiofrequency energy (RF) in the treatment of resistant hypertension. However, using RF energy causes transmural arterial damage before achieving denervation of the periarterial sympathetic nerve plexus. An in vitro trial evaluated ultrasound energy and found that the tested form of energy can minimize or even eliminate injury to the renal artery. Ultrasound energy has the ability to propagate thorough blood and produce controlled heating, without requiring direct contact with the tissue. Methods: We enrolled 10 patients with a history of drug-resistant hypertension (defined as systolic blood pressure ≥140 mmHg during 24 Hr ambulatory blood pressure BP monitoring), treated with ≥ 3 anti-hypertensive drugs. Additionally, renal artery diameter ≥5 mm was required. The SOUND-ITV study, utilized an ultrasound catheter (Sound Interventions, Inc, Stony Brook, NY). At the distal end of the catheter is a miniature, tubular piezoelectric transducer, which is placed inside a non-occlusive balloon that is inflated with sterile water within the renal artery. Water circulation maintains an acceptable catheter temperature. The piezoelectric transducer converts electrical energy to acoustic energy and emits it over the full circumference. The average number of energy applications delivered to each renal artery was 1, 8; the energy application time was less than 2 minutes per patient. Results: The mean values of ambulatory systolic BP before procedure were 169, 5 mmHg, at three months 147, 4 mmHg (P value equals 0.0407), and atsix months after procedure 154, 5 mmHg (P value equals 0.1975). The mean values of ambulatory diastolic BP before procedure were 95 mmHg, at three month 82, 2 mmHg (P value equals 0.0381), and at six months after procedure 83, 5 mmHg (P value equals 0.1364). Anesthesia was administered according to standard hospital protocol and procedure was well tolerated. Arterial spasms were not observed during the procedure. There were no changes in luminal dimensions. The post-treatment arterial lumen geometry was assessed by angiography (n 10) and IVUS (n 7) immediately post-procedure, and by CT scan (n=10) at 3 months. Conclusion: This first-in-man experience demonstrates the ability of circumferential intravascular therapeutic ultrasound to significantly improve blood pressure in patients with resistant hypertension. Longer term follow-up is necessary to confirm these results.