Angina or MI-- What's the Diff?

     Angina is a heart condition that occurs when plaque builds up along the inner walls of the coronary arteries, narrowing the artery lumen (opening) and reduces the blood flowing through the artery to the heart muscle.  This results in a decrease amount of oxygen being supplied to the myocardium and causes ischemia.  The ischemia causes chest pain.  Stable angina is when the pain is predictable and follows a pattern, such as after exertion.  It will resolve with rest or with medication, such as a nitrate.  Stable angina is not a myocardial infarction, but may indicate a potential MI in the future.  Unstable angina is chest pain that does not follow a pattern and does not resolve with rest or medication.  In fact, it could occur at rest.  This indicates a very serious problem that requires immediate attention.  If the ischemia is not reversed quickly, the result could be an MI.

                                               

    

     In diagnosing an MI, an electrocardiogram (EKG or ECG) is performed.  During angina, there may be ST segment depression and/or T-wave inversion, indicating ischemia.  With prolonged ischemia, the ST segment will become elevated, indicating injury to the muscle.   During an infarction, when the tissue becomes necrotic, pathological Q-waves will form. 

 

                                          

 

 

 

       Cardiac enzymes, or markers, can also be used to diagnose an infarction.  The most reliable are  troponin levels, which become elevated after injury to the cardiac muscle occurs.  Sometimes a creatinine kinase (CK) is drawn, but is not as reliable because unlike troponins, which is sensitive to the cardiac muscle, CK level can become elevated with any skeletal muscle injury.

 

      To correct an infarction, an angioplasty may be ordered to locate the blockage in the coronary artery.  A balloon is guided along a wire into the artery and inflated at the site of the blockage to crush the plaque and widen the artery.  Sometimes a stent is placed in the artery to keep it open.

 

 

 

      For severe blockages, a coronary artery bypass graft (CABG) may be necessary.  This is when a healthy artery or vein is connected to the blocked coronary artery so that the blood flows past, or bypasses, the blockage.

 

     Telling the difference between angina and a myocardial infarction can be difficult since the symptoms are similar.  It is always best to seek medical attention, to be on the safe side, since untreated or unresolved ischemia can lead to permanent heart muscle damage or worse-- death.



 

 

Drug of the Week:  Nitroglycerin