THE BEAT GOES ON:  THE CARDIOVASCULAR

SYSTEM AND CIRCULATORY PHYSIOLOGY

Audience Q & A

Question:  When is a pacemaker used?

Answer:  A pacemaker is used when there is a problem in the heart’s electrical system.  Electrical impulses from the heart’s pacemaker – the sinus node – sends impulses to the rest of the heart to cause it to beat in a coordinated fashion.  If a disease process causes an abnormality in the sinus node or anywhere else in the pathway, and the patient is experiencing symptoms because of this, then the patient will likely need a pacemaker.

--Conrad Smith, M.D.

Question:  What is the best way to detect a patient’s potential for heart disease?  What can I do to minimize my chances of heart trouble in the future?

Answer:  There are several ways to determine if someone is at risk for having coronary artery disease.  The simplest is to evaluate their risk factors.  The five commonly recognized risk factors are smoking, hypertension (high blood pressure), diabetes, elevated cholesterol, and a family history with a primary family member (mother, father, brother, or sister) who has coronary artery disease before the age of 50.

In addition, there are diagnostic tests that can be performed, such as an ultrafast CT, which can evaluate a patient for coronary artery calcification.  If the patient has a low calcium score, they are much less likely to have coronary artery disease.  A more sensitive method is a stress test that will determine, with an approximate accuracy rate of 90 percent, whether someone has significant coronary artery disease.  Finally, the diagnostic gold standard is cardiac catheterization, a procedure in which the coronary arteries are directly visualized with a special x-ray camera.

The best way for an individual to minimize the likelihood of having heart trouble is to know and modify risk factors as much as possible.  Here are some recommendations of benefit to anyone trying to avoid heart disease:

• Eat a diet low in saturated fat and cholesterol to keep total cholesterol value less than 200 mg/dl.
• Keep LDL (bad) cholesterol less than 135 mg/dl.
• Take prescribed medications exactly as ordered and be especially careful with diet if high blood pressure or diabetes have already been diagnosed.
• Eliminate smoking and encourage others to quit smoking to eliminate any exposure to second-hand smoke.
• Be particularly aggressive in working on risk factors if there is a family history of coronary artery disease, particularly in a primary relative.

--CS

Question:  What are stents made of?  What keeps them in place?  Why doesn’t the body reject them?

Answer:  Stents are made of stainless steel.  They are expanded to a size greater than or equal to the size of the vessel.  The stents are designed so that, when they are expanded appropriately, they are embedded into the vessel wall and won’t move.  After about six weeks, the body will grow a thin layer of cells over the stent.  The stent actually becomes a part of the vessel wall.  Many animal experiments were performed to evaluate the likelihood of an immune reaction (rejection) of the stent.  The studies showed no evidence of rejection with stainless steel, and the results were consistent with those of other metal devices that have been surgically implanted in the body without being rejected.

--CS

Answer:  Plaque is made up of fatty tissue.  The clot is made up of blood components – red blood cells, platelets, and proteins.  Clot-dissolving medicines called thrombolytics can break down the proteins, which act as a mesh upon which red blood cells and platelets form a clot.  If the clot is large, it can completely block a coronary artery and cause a heart attack.  The fatty tissue builds up over years, unlike the blood clot that can build up over minutes to hours.  Clot-dissolving medicines have no effect on the fatty tissue.

--CS