This is a 68-year-old male patient who was cutting the grass when he experienced a “horrid pressure in my chest.” He says, “it feels like it is going to explode.” He rates his discomfort as an 8 on a scale of 10 and describes it as an intense pressure. He complains of feeling dizzy. His history includes being a Type II Diabetic for the past 10 years, hypothyroidism and HTN. He is a pack-a-day smoker for at least 30 years.
His father died at the age of 46 of a heart attack. His mother is alive and well. His 61-year-old brother just had “bypass surgery” last year. He takes “a pill for his thyroid and one for his high blood pressure,” but can’t identify what they are.
Physical examination reveals a moderately overweight male who is obviously uncomfortable. His skin is pale and diaphoretic. He is finding it hard to concentrate on questions because of the pain. His pulse is 78, weak but regular. His respirations are 26 with a pulse oximetry reading of 96%. His blood pressure is 92/64. He is placed on the monitor and found to be in sinus rhythm. A 12-lead ECG is completed and is shown above.
This is a large inferior wall infarction. Note the high ST-segment elevation in II, III, and aVF. There are reciprocal changes in the anterior wall (ST depression in V1, V2 and V3). This patient needs to be treated quickly for his STEMI. However, a significant number of inferior wall infarction affect the right ventricle. This information is important because these patients may be severely hypotensive if given nitroglycerin (NTG) and our patient is borderline hypotensive, to begin with.
This diagnosis can be made by moving V4 from the left side to the right side. If there is 1mm or more ST elevation in V4R, the right ventricle is involved and NTG should be held. This will not catch all right ventricular infarctions, but it will diagnose the large ones. These are more likely to develop hypotension with NTG.
TREATMENT: Our goal is getting this blood vessel open and saving heart muscle. We know that the longer the vessel remains closed, the more heart muscle will be lost. If we are an EMS provider, the receiving hospital should be notified immediately so that the cardiac catheterization laboratory can be ready when we get there. If we are an emergency department provider, the cardiac catheterization laboratory should be activated as soon as the diagnosis is made.
The patient should receive aspirin 325mg (he is not taking daily aspirin). He should get 4 baby ASA as they can be chewed and absorbed quicker than adult aspirin given PO.
An IV infusion of normal saline solution should be started to maintain his blood pressure. His current blood pressure is marginal at best and we know that inferior wall myocardial infarction can become hypotensive very quickly.
His pain should be treated. Morphine is the drug of choice for the pain of infarction. However, it should be used with caution in the treatment of unstable angina.
He does not require supplemental oxygen because his oxygen saturation is >94% on room air and he is not complaining of shortness of breath.