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AF Association PO Box 6219 Shipston-on-Stour CV37 1NL +44 (0) 1789 867 502 ™ AF A [email protected] www.afa.org.uk www.afa.org.uk Rate limiting calcium channel blockers

Introduction activity levels. Rate limiting calcium channel

blockers can be used alone or in combination Rate limiting calcium channel blockers- The calcium channel blockers are a type of with other medication such as beta blockers medication which affect many cells within the or . body. It is split into two families, the Dihydropyridines which mainly have a role in : The rate limiting calcium the management of and high channel blockers are effective pressure which share these properties but also reducing medications. However their related have a use in changing the rate and rhythm of medication, the Dihydropyridines, are more the heart. The second group can be used either commonly used in this setting. alone or in conjunction with other medications to help in the management of atrial fibrillation. Side effects and problems The two examples are verapamil and diltiazem. : Due to their effect on the strength How do they work on heart muscle contraction the rate limiting calcium channel blockers should not be used in These medications affect the way that calcium who have problems with the strength salts are moved into the muscular cells of the of their heart beat. These patients are classed body. In the arteries this leads to widening of as having heart failure also referred to as left the artery and this causes a drop in blood ventricular impairment. pressure. In the heart this leads to a less contractual force on the muscle cells and Lightheadedness: Due to their ability to drop the P reduces the overall force of the heart beat. This blood pressure, in some people this may give atient information change to the flow of calcium also affects the a sensation of lightheadedness or dizziness. conduction of the heart beat from the upper chambers of the heart to the lower chambers. Ankle swelling: Due to their effect in widening In this way it has an effect of slowing the heart the arteries and veins these medications can beat. This is unlike beta blocking medications occasionally cause ankle swelling. This will that slow the heart beat by also having an return to normal when the medication effect on the adrenalin receptors in the heart. is discontinued.

Clinical use Use with beta blockers: Diltiazem can be used in conjunction with beta blockers to Antiarrhythmic: Rate limiting calcium channel assist with heart rate reduction. The companion blockers can be used to try to maintain the verapamil should only be used together heart in its normal rhythm. Verapamil is the with a under specialist guidance. most frequently used drug for this purpose and is often used in people who cannot tolerate beta blocker medication.

Rate reduction: Some patients with atrial Author: Dr Matthew Fay, GP fibrillation find that their heart races which can Endorsed: Professor A John Camm, EP cause unpleasant symptoms and reduce their Mrs Jayne Mudd, Arrhythmia Nurse Specialist

Founder & Chief Executive: Trudie Lobban MBE Trustees: Professor A John Camm, endorsed by by ® Professor Richard Schilling, Mrs Jayne Mudd and Dr Matthew Fay www.aa-international.org (c) 2011 Registered Charity No. 1122442 Affiliate Re-printed January 2011 1