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Arterial dilation and reduced wave reflection. Benefit of dilevalol in hypertension
1Medical Professorial Unit, St. Vincent's Hospital, Sydney, New South Wales, Australia.
Insights
Dilevalol and atenolol equally reduced arterial stiffness in hypertensive patients. However, dilevalol more effectively reduced wave reflection, indicating a greater vasodilatory effect on arteries.
Area of Science:
- Cardiovascular Pharmacology
- Hypertension Management
- Arterial Biomechanics
Background:
- Essential hypertension is characterized by increased arterial stiffness and wave reflection.
- Labetalol and its isomer dilevalol are used to manage hypertension.
- Atenolol is a beta-blocker commonly prescribed for hypertension.
Purpose of the Study:
- To compare the effects of dilevalol and atenolol on arterial distensibility and wave reflection in patients with essential hypertension.
- To assess the impact of these antihypertensive drugs on pulse wave velocity (PWV) and augmentation index.
Main Methods:
- A double-blind, crossover, placebo-controlled trial involving 12 patients with essential hypertension.
- Administration of dilevalol (200-400 mg/day) and atenolol (50-100 mg/day) for 12 weeks each, separated by a placebo period.
- Noninvasive measurement of carotid pressure waveforms, aortic, arm, and leg PWV, and calculation of the augmentation index.
Main Results:
- Both dilevalol and atenolol significantly reduced brachial blood pressure and PWV in all measured arterial segments compared to placebo.
- There was no significant difference between dilevalol and atenolol in reducing arterial distensibility (PWV).
- Dilevalol significantly reduced the augmentation index (wave reflection) compared to atenolol, suggesting a greater peripheral vasodilatory effect.
Conclusions:
- Dilevalol and atenolol are equally effective in improving arterial distensibility in hypertensive patients.
- Dilevalol demonstrates a superior effect in reducing arterial wave reflection compared to atenolol.
- The enhanced reduction in wave reflection by dilevalol may be attributed to its vasodilatory properties on peripheral conduit arteries.
Abstract:
We compared dilevalol (an isomer of labetalol), 200-400 mg daily, against atenolol, 50-100 mg daily, in a double-blind, crossover, placebo-controlled trial with respect to effects on arterial distensibility (measured as pulse wave velocity [PWV]) and wave reflection (assessed from carotid pressure wave contour). Twelve patients of mean age 58 years (range 44-73 years) with essential hypertension (supine diastolic blood pressure 95-114 mm Hg) took active therapy for 12 weeks, separated by a 2-4 week placebo period. Carotid pressure waveforms were recorded noninvasively by applanation tonometry with a Millar micromanometer-tipped probe. PWV was measured between carotid and femoral arteries (aortic PWV), carotid and radial arteries (arm PWV), and femoral and pedal arteries (leg PWV). Early wave reflection was calculated from the ratio of the height of the peak of the carotid wave above its shoulder to the pulse pressure and was expressed as an augmentation index. Both drugs were equally effective in reducing brachial sphygmomanometric pressure and PWV in all three regions (active vs. placebo, p less than 0.001), but there was no significant difference between the two active therapies. However, the augmentation index (averaged during the treatment period) was significantly lower with dilevalol (19%) than with atenolol (28%, p less than 0.01), corresponding to a greater decrease of 5-8 mm Hg in carotid systolic pressure compared with the brachial artery. Although both drugs were equally effective in reducing arterial distensibility, the vasodilating action of dilevalol gave added benefit in reducing wave reflection, presumably through its vasodilatory effect on peripheral conduit arteries.