Fast Five Quiz: Myocardial Infarction Clinical Keys

Yasmine S. Ali, MD

Disclosures

November 13, 2020

Physical examination findings for MI vary; one patient may be comfortable in bed, with normal examination results, whereas another patient may be in severe pain, with significant respiratory distress and a need for ventilatory support.

In patients with acute inferior-wall MI with right ventricular involvement, distention of neck veins is commonly described as a sign of failure of the right ventricle. Impaired right ventricular function also leads to systemic venous hypertension, edema, and hepatomegaly.

In general, the patient's blood pressure is initially elevated (hypertension due to peripheral arterial vasoconstriction resulting from an adrenergic response to pain, anxiety, and ventricular dysfunction). Alternatively, hypotension can also be seen. Usually, this indicates either right ventricular MI or severe left ventricular dysfunction due to a large infarct area or impaired global cardiac contractility.

Fever is usually present within 24-48 hours, with the temperature curve generally parallel to the time course of elevations of the blood creatine kinase level. Left ventricular function and peak body temperature or determined markers of inflammation are not significantly correlated.

On palpation, lateral displacement of the apical impulse, dyskinesis, a palpable S4 gallop, and a soft S1 sound may be found. These signs indicate diminished contractility of the compromised left ventricle. Paradoxical splitting of S2 may reflect the presence of left bundle branch block or prolongation of the pre-ejection period with delayed closure of the aortic valve, despite decreased stroke volume. A new mitral regurgitation murmur (typically holosystolic near the apex) indicates papillary muscle dysfunction or rupture, or mitral annular dilatation; it may be audible even when cardiac output is substantially decreased.

Read more about the physical findings associated with MI.

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