Questions on cardiac material

I got some really good questions on our cardiac material and thought I’d share them with you.

Q. Previously I thought that “pre-HTN” was a systolic BP of 140, and HTN was considered 160. Would you consider someone with a systolic over 140 to be hypertensive and put them on a preventative statin?

A. The diagnosis of hypertension is made when the average of 2 or more systolic pressure readings (on 2 or more separate visits) is greater than or equal to 140, OR when the average of 2 or more diastolic readings (on 2 or more separate visits) is greater than or equal to 90. Some sources say 3 visits; the point is, it can’t be just one reading on one visit.

Prehypertension is when a patient’s average blood pressure is between 120/80 and 140/90.

Usually, the first step after diagnosis (unless the patient has a very high blood pressure) is to make some lifestyle changes, including:

  • Eat a diet rich in potassium and fiber, and drink lots of water
  • Exercise regularly (30 minutes/day)
  • Quit smoking
  • Limit alcohol (1 drink/day for women, 2 drinks/day for men)
  • Limit sodium (less than 1,500 mg/day…the less the better!)
  • Reduce stress (meditation and yoga have been proven beneficial)
  • Stay at a healthy body weight.

If lifestyle changes don’t bring the blood pressure down to normal, then drug therapy is used.

Q. How are atherosclerotic plaques located in the body, and are they only checked for after an atherosclerotic event occurs?
A. Did you mean where? If so, they can occur anywhere in the arterial system (they almost never occur in the venous system). The most common and problematic places are the coronary arteries and the arteries serving the brain (like the carotid) – but plaques can be found anywhere: aorta, renal arteries, etc.

Generally, you only check for them once you have some indication that the patient has atherosclerosis…like symptoms of angina, or a transient ischemic attack (which is like a mini-stroke that is reversible), or something worse (like a myocardial infarction or a stroke). You can do an angiogram to see how blocked the coronary or carotid (or other) arteries are.

Q. Dr. Katz told us in physiology that a “normal” kidney would excrete all excess sodium, therefore a high sodium diet with a normal kidney was OK. Therefore, is a low sodium diet only beneficial in people with reduced renal sodium excretion associated with HTN?

A. I know – that is confusing. I am sure that Dr. Katz is right (and I also remember that from medical school): the kidney normally secretes excess sodium in the urine to maintain a normal blood sodium level. However, it is also true that low sodium diets (even in people with normal renal function) are associated with a lower risk of myocardial infarction, and high-sodium diets (even in people with normal renal function) are associated with a higher risk of myocardial infarction. I’m not sure how to reconcile these two findings – it seems that the kidney should simply excrete any excess sodium you ingest, thereby regulating blood pressure – but apparently there is more to it than that.

Interesting: cultures in which people ingest less than 50 mg of sodium a day (yes, 50!! Our guidelines say to eat less than 1,500!) have a very, very low incidence of myocardial infarction.

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