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Significant narrowing of the left main coronary artery is a high-risk condition with significant mortality risk. Bypass surgery is the current gold-standard treatment for unprotected left main (ULM) disease. Stenting utilizing drug-eluting stents (DES) is another therapeutic option for patients with ULM disease considered too high risk for bypass surgery or for patients who simply refuse bypass surgery. We have had great initial success with ULM stenting using DES in 10 selected patients at Baylor University Medical Center. Ongoing multicenter, international randomized studies comparing percutaneous coronary intervention with DES and bypass surgery will shed more light on the best treatment strategy for ULM coronary disease.

Despite the use of combination drug therapies, many patients still have uncontrolled hypertension. Resistant hypertension is defined as a blood pressure that remains above goal in spite of compliance on ≥3 antihypertensive medications of different classes, one of which must be a diuretic. Renal denervation therapy attempts to address this difficult-to-treat population by blocking the sympathetic nerve activity to the kidneys. Treatment of systemic hypertension with sympathectomy was initiated in the 1930s. In 1953, Smithwick and Thompson described 1266 cases of sympathectomies performed for treatment of patients with systemic hypertension. They found that there was a significant mortality benefit in the treated patients, but at a cost of a significant increase in morbidity, mainly due to postural hypotension, gastrointestinal disturbances, and impotence (1). Dr. Thompson went on to have a long and distinguished career. He practiced vascular surgery at Baylor for over 30 years, during which time he was the chairman of the Department of Surgery from 1982 to 1986. The Symplicity renal denervation system (Figure ​(Figure11) is a novel treatment utilizing a minimally invasive catheter-based procedure that uses radiofrequency to ablate the sympathetic nerves lying in the renal artery. It is believed that blocking the sympathetic nervous system will lead to a reversal of fluid and salt retention and reduce the inappropriate release of renin that is contributing to uncontrolled hypertension. Blocking the renal sympathetic nerves has also been shown to have beneficial effects on organs damaged by chronic sympathetic overactivity, including the blood vessels, kidneys, and heart (2). Figure 1. Symplicity renal denervation system. Image courtesy of Medtronic. The nonsurgical procedure is performed endovascularly with access through the femoral artery. Prior to denervation, a renal artery arteriogram is performed to rule out any hemodynamically significant renal artery stenosis. The renal nerves are arborized around the renal arteries and lie within the adventitial layer of the vessel (Figure ​(Figure22). The Symplicity renal denervation system is placed into each renal artery, and radiofrequency ablation (5–8 watts) is performed with four to six 120-second treatments starting distally and moving proximally, with spacing of 5 mm between treatment sites. Figure 2. Renal nerves arborized in the adventitial layer of the renal arteries. Image courtesy of Medtronic. The Symplicity HTN-1 Trial was a multicenter nonran­domized open-label proof-of-concept study that enrolled 153 patients with medically resistant hypertension. Patients received catheter-based renal denervation plus baseline antihypertensive medications and were followed for 36 months. At 6 months, the average drop in blood pressure in the patients was 22 mm Hg systolic and 10 mm Hg diastolic. These results at 36-month follow-up showed a 33 mm Hg systolic and 19 mm Hg diastolic blood pressure reduction (Figure ​(Figure33). There were no reported events of vascular injury or change in renal function (3). Figure 3. Symplicity HTN-1 Trial: 36-month results. Image courtesy of Medtronic. These data led to the Symplicity HTN-2 Trial, which was a multicenter international randomized controlled study comparing renal denervation plus baseline antihypertensive medications versus baseline medications alone. After 6 months, the treatment arm had a mean reduction of 33 mm Hg in the systolic blood pressure and 12 mm Hg in the diastolic blood pressure (Figure ​(Figure44). The control arm did not have any change in blood pressure. There were no major procedure or device-related events (4). Figure 4. Symplicity HTN-2 Trial results. Image courtesy of Medtronic. These two trials are the basis of the Symplicity HTN-3 Trial, which is a single-blinded, randomized controlled trial designed to evaluate the safety and effectiveness of the Symplicity renal denervation system in patients with resistant hypertension. This trial plans to enroll 530 patients who will be randomized to receive either renal denervation plus anti­hypertensive medications or a sham procedure and antihypertensive medications. The primary endpoints will be change in blood pressure from baseline at 6 months and the incidence of adverse events at 1 month following randomization. There are three inclusion criteria: 1) having an average systolic blood pressure ≥160 mm Hg; 2) being on three antihypertensive medications, one of which is a diuretic; and 3) being 18 to 80 years old. The exclusion criteria include 1) hemodynamically significant renal artery stenosis; 2) glomerular filtration rate