Saturday, Oct. 9 news tips


From the American Heart Association 58th Annual High Blood Pressure Research Conference

***Embargo times listed with each abstract***

All embargoes lift by 3 p.m. CDT (4 p.m. EDT) on the day of presentation. Presentation time is listed if embargo is different from presentation time.

3 p.m., Saturday, Oct. 9
(Presentation time: 6 p.m., Saturday, Oct. 9).
Abstract P37 Researchers urge caution for cardiovascular disease patients taking new alertness medication. Researchers evaluated the cardiovascular changes that occur when people take modafinil (Provigil), a wakefulness-promoting drug that treats daytime sleepiness associated with sleep apnea (brief periods of recurrent cessation of breathing during sleep), sleep disorders associated with working a night or rotating shift, and narcolepsy (a condition that induces excessive drowsiness and unintended sleep episodes during the day). Modafinil, which reduces fatigue and enhances wakefulness and concentration, has gained favor because it has fewer side effects than other stimulants.

In this randomized, double-blind crossover study, researchers studied 11 normal hospitalized volunteers (average age 31) given a placebo or 400 mg of modafinil. When taking modafinil, subjects had significant increases in resting heart rate (6.3 beats per minute), diastolic blood pressure (4 mmHg) and systolic blood pressure (5.5 mmHg). After finding these and other modafinil-induced changes in the autonomic nervous system (which adjusts heart rate, the heart's ability to contract, blood vessel size and blood pressure in response to stress), researchers encourage caution in using modafinil in patients with cardiovascular disease.

3 p.m., Saturday, Oct. 9
(Presentation time: 6 p.m., Saturday, Oct. 9).
Abstract P67 Low-salt diet keeps arteries flexible in people with difficult-to-control high blood pressure. For the first time in humans, researchers have shown that eating a low-salt diet can protect the arteries against stiffening in patients with resistant hypertension (uncontrolled on three or more medications). Researchers evaluated 120 people with resistant hypertension and determined that 34 had aldosteronism high levels of aldosterone (a hormone secreted by the adrenal glands that affects blood pressure and salt balance), but low plasma renin activity. Renin is an enzyme released by the kidney to help control the body's salt and fluid balance and blood pressure.

Using ultrasound, researchers measured the diameter of the brachial artery in the upper arm. The ability of an artery to relax and expand in response to increases in blood flow (FMD, or flow mediated dilation) is a sign of a flexible artery with a healthy inner lining (endothelium). In these 34 patients, they found that the 10 who were eating a low-sodium diet had significantly more flexible arteries (average FMD 2.6 percent) than the 24 eating a high-sodium diet (average FMD 1.6 percent). The groups were similar in age, body mass, blood pressure, medication use and aldosterone excretion. Five subjects who consumed very little sodium had the best FMD (3.4 percent). The results indicate that reducing salt intake can protect against aldosterone-induced reduction in blood vessel flexibility, and that measuring urinary aldosterone and sodium may help predict cardiovascular risk in patients with resistant hypertension.

Source: Eurekalert & others

Last reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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