What is the proposed mechanism of action for beta blockers in the treatment of heart failure?

Increased adrenergic activity in patients with congestive heart failure can downregulate cardiac beta-adrenergic receptors and cause peripheral vasoconstriction. Beta blockers can attenuate these deleterious effects of chronic catecholamine stimulation. Clinically, this has translated into improvements in hemodynamics, symptoms, exercise tolerance, and left ventricular function. Beta blockers, however, have not been shown to decrease mortality in this setting.

1In patients with left ventricular (LV) hypertrophy induced by hypertension, do beta blockers reduce LV mass? How do they compare with other agents?

Beta blockers have been shown to cause regression of LV mass in hypertensive patients with LV hypertrophy. In a meta-analysis, LV mass was reduced an average of 8%, as compared to 15% for angiotensin-converting enzyme (ACE) inhibitors, and 8.5% for calcium channel blockers. Diuretics decreased LV mass an average of 11.3%, but this was attributed to a reduction in LV volume and not reversal of wall hypertrophy as seen with the other drug classes.

1A hypertensive patient presents with an acute aortic dissection. What would proper emergency management include?

While immediate lowering of blood pressure is essential acute therapy for aortic dissection, initial use of nitroprusside may increase the force and velocity (dP/dT) of ventricular contraction, which may increase aortic shear forces and accelerate the propagation of the dissection. By reducing dP/dT, beta blockers decrease aortic shear forces and allow safer introduction of nitroprusside. Labetalol, with its combined beta- and alpha-adrenergic blockade, can be administered intravenously and is a single agent alternative to the more traditional therapy.

The opinions and assertions contained herein are the private views of the authors and are not to be construed as official or reflecting the views of the Department of the Army or Department of Defense.

What anticoagulant and antiplateiet agents are commonly used in cardiology?

The main anticoagulants used are warfarin, given orally, and heparin, given intravenously or subcutaneously. The antiplatelet drug used in the most recent clinical trials is aspirin.

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