Doctors have changed their view of high blood pressure, also termed hypertension. It was once believed the condition was sometimes a good thing required for survival (previously called “Essential Hypertension”). Now we know hypertension shortens life and may cause terrible complications like stroke, heart attack and heart failure.

Many studies over the past 20 years give clear evidence in both rodents and patients, once kidney disease of any cause begins, high blood pressure makes it progress to what we call end-stage renal failure (ESRD). The good news is once doctors learned hypertension was bad for us, they were able to make plans for lowering blood pressure level and thus to slow the bad course of chronic kidney disease (CKD). The new buzz word for slowing the march of CKD is “Renoprotection.”

At the center of renoprotection are two principles:

1. Do not do things that hurt the kidneys such as taking drugs known to injure the kidney (some antibiotics, high doses of lithium as examples).

2. Block the system that makes the blood pressure rise in diseases like diabetes.

We now understand a central enzyme called Angiotensin Converting Enzyme (ACE) stimulates formation of angiotensin II (a powerful vasoconstrictor, meaning it makes small arteries close off blood flow, in turn causing other harmful substances to be released). ACE secretion plays a major role in regulating blood pressure and reducing the burden on the heart. This improves the heart’s ability to pump blood around the body. It is the turnoff of blood flow that leads to growth of new blood vessels in the retina (back of the eye) that bleed in diabetes. Similarly, the reduction in blood flow stops the kidney from functioning and makes muscles work less well. Diseased blood vessels may hemorrhage (bleed) leading to strokes when the bleeding happens in the brain.

Drugs that stop or inhibit the action of ACE are called ACE inhibitors (ACEi). ACEi have become routine in the treatment of hypertension and congestive heart failure. They can also be used for diabetic nephropathy (kidney problems in people with diabetes) and after a heart attack should the heart muscle be not working well.

Examples of ACEi include:

• Benazepril – Cibacen
• Captopril – Capoten
• Cilazapril – Inhibace
• Enalapril – Renitec
• Lisinopril – Prinivil, Zestril
• Perindopril – Coversyl
• Quinapril _ Accupril
• Trandolapril – Gopten, Odrik

Like every drug prescribed, ACEi may have unwanted side effects. The most troublesome is a persistent dry cough that can afflict as many as 20 percent of the people taking the drug – they usually have to switch to another blood pressure lowering medicine. Other side effects are: low blood pressure, temporary worsening of kidney function, skin rash, stomach upset, light sensitivity, headache, dizziness, fatigue and taste disturbances. ACEi are one of the most frequent causes of a high blood potassium level that may interfere with the heart’s electrical action. All of these side effects mean frequent blood chemistry checks are needed whenever a patient continues on ACEi.

ACEi should not be taken when pregnant or breastfeeding or when the patient is known to be allergic to the drug. The doctor will tell the patient about other limits on the drug’s use especially if the patient has liver disease. In the first few days of starting ACEi therapy, the patient may get up slowly out of bed. Feeling dizzy or light-headed when standing up is also common.

A related series of drugs, called angiotensin receptor blockers (ARBs) achieve the same goal of stopping the unwanted blood pressure elevating action of angiotensin. Use of ARBs is now often combined with ACEis in a powerhouse renoprotection strategy that has delayed the onset of ESRD in patients with CKD for a decade and longer.

We really have come a long way from the time when we were crazy enough to believe that hypertension was essential to survival!

Eli Friedman, MD, is Chief of the Division of Renal Disease for State University of New York, Health Science Center at Brooklyn. He is also a Chairman of the AAKP Medical Advisory Board and is an AAKP Life Member. This article originally appeared in the April 2007 issue of Kidney Beginnings: The Magazine.