ACE inhibitors

Our specialist helpline nurse Robert Hall discusses the group of medications called ACE inhibitors, and their use in cardiomyopathy.

Angiotensin converting enzyme inhibitors, commonly known as ACE inhibitors, are one of the standard drugs to treat a heart failure condition, such as dilated cardiomyopathy. There are various types of ACE inhibitors and you can always recognise them as their names always end in ‘pril’. The most common one used currently is ramipril. The drug acts to interrupt the body’s response when there is a low blood pressure. 

Briefly, in order to regulate the blood pressure and the volume of fluid in the body there is a process called the ‘renin angiotensin’ system. When the body recognises there is a drop in the pressure of the blood flowing to the kidneys it causes a substance called renin to be released. This promotes the production of angiotensin I. The angiotensin converting enzyme then acts to convert the angiotensin I to produce the hormone angiotensin II. Angiotensin II has two main actions, firstly it causes constriction of the smooth muscles surrounding blood vessels in the body. Secondly, it promotes the production of a hormone called aldosterone. This acts to increase the reabsorption of sodium and water. The resulting tightening of the blood vessels and the increase in fluid volume in the body causes an increase in the blood pressure. 

Normally this control mechanism of the blood pressure responds to any changes and ensures the body maintains an adequate circulation of blood to the vital organs. However, when the heart is affected by a condition like dilated cardiomyopathy and already struggling to pump effectively the constricting of the blood vessels and the increase in blood volume can increase its workload and worsen symptoms. ACE inhibitors interrupt the conversion of angiotensin I, thereby reducing the production of angiotensin II. This lessens the workload of the heart and helps to improve its function.

As the drug has the effect of lowering the blood pressure it is necessary to start at a lower dose and increase it gradually, to allow the body to become accustomed to its action.

Common side effects of ACE inhibitors include a dry cough, increased blood potassium levels, fatigue, dizziness and a reduced kidney function. These may vary according to the type of ACE inhibitor. Where the side effects of ACE inhibitors cause difficulties people can usually be switched over to another group of drugs call angiotensin II receptor blockers, the ‘sartans’, e.g. losartan. These have a similar effect but rather than inhibit the production of angiotensin II they limit its effect.

This article is taken from an original discussion on our Facebook page (opens new window).
Read this article on Facebook.

© Cardiomyopathy UK. March 2018.