Use of nitroglycerin

Posted By  CCF Cardio MD-SGM on November 13, 1997 at 11:22:59:

In Reply to: Use of nitroglycerin posted by Edward Cabaniss on October 23, 1997 at 10:34:09:

: I have recently had problems with high cholesterol and blocked arteries.  Diet and medication have significantly lowered my cholesterol count.  Apparently, collateral circulation had already begun to develop naturally around the major blocked artery and doctors recommended medication and exercise rather than surgery.  I am taking aspirin, zocor, and norvasc.  They also recommended nitroglycerin to expand the blood circulation.  I have decided not to take the nitroglycerin because it is my belief that my collateral circulatory system will grow more rapidly if it is moderately stressed (e.g. the arteries have not been artificially expanded with nitroglycerin).  Is there any research which would support or criticize my approach?

[CCF Cardio MD-SGM]

Dear Mr. Cabaniss,
You pose a specific question that doesn't have an absolute answer. However, I'll try to discuss what I consider to be the relevant issues here...   Nitroglycerin does cause dilation of the coronary arteries, thus providing increased blood and oxygen to the heart muscle.  In addition, Nitroglycerin causes changes certain hemodynamic parameters that result in a reduction in myocardial work.  Finally, it may reduce platelet aggregation and thus help to inhibit the formation of microscopic blood clots in the coronary arteries.  These benefits are real and well documented.  We think that patients with coronary disease that have symptoms or signs of myocardial ischemia (such as angina, or evidence of ischemia on stress testing) should take nitroglycerin.  However, if there is no evidence of ischemia, the benefit of nitroglycerin is less clear.  
Regarding the issue of collateral circulation, you're correct in your understanding that the body will provide its own "micro"-bypasses to provide blood to heart tissue that is underperfused.  Nitroglycerin may, theoretically, retard this process, but there is no hard evidence to support this.  However, we do know that ischemia is a dangerous thing and must be treated aggressively.  If your doctors have prescribed nitroglycerin to treat ischemia, then it would be prudent to take this medication.  
Best of luck. Information provided in the heart forum is intended for information purposes only. Please consult your physician for specific diagnoses and recommendations.