Question

Mrs. T., a 74-year-old white woman, drove herself to the emergency department, arriving at 10:30 AM. She complained of substernal chest pain with radiation to her back that began 1 hour ago. The pain is not relieved by rest or one sublingual nitroglycerin. She describes the pain as dull and rates it a 7 on a scale of 10. She feels nauseated but has not vomited. Mrs. T. has a history of hypertension, diabetes, and elevated cholesterol levels. She has no known drug allergies. On physical examination, Mrs. T. is awake, alert, oriented, and anxious. Her skin is cool and diaphoretic. Blood pressure is 96/52 mm Hg; heart rate, 112 beats/min and regular; respiratory rate, 22 breaths/min; oxygen saturation, 92%; and temperature, 98°F (36.7°C). Cardiac examination reveals S1, S2, and an S3. She has no jugular venous distention. Peripheral pulses are present but thready, and there is 1+ pedal edema bilaterally. Auscultation of the lungs reveals bilateral basilar crackles. She has no evidence of cyanosis or clubbing. Her abdominal examination shows positive bowel sounds in all quadrants. Her abdomen is soft and nontender with no palpable masses. The nurse immediately records a 12-lead ECG that shows a 4-mm ST-segment elevation in leads II, II, and avF. Blood samples are drawn that reveal an elevated troponin level. Mrs. T. is given an aspirin, and an intravenous (IV) line is started. Her pain is treated with IV morphine sulfate. Mrs. T. is diagnosed with an acute STEMI in the inferior wall and is admitted to the coronary care unit. On day 2 after admission, Mrs. T complains of chest pain that is made worse by deep breathing and is somewhat relieved when she sits up and leans forward. She has a low-grade fever. On physical examination, she displays a pericardial friction rub upon auscultation of her heart.

1. Mrs. T. was diagnosed with an inferior wall myocardial infarction. What coronary artery is most likely occluded and what potential complications are priorities for you to monitor?

2. In addition to the routine 12-lead ECG, what other electrocardiographic monitoring steps should you take and why?

3.  What may be the cause of Mrs. T.’s pain on day 2?

Answer 1

1. The inferior wall myocardial infarction occurs due to infarction of inferior region of the heart. The inferior cardiac region is supplied by posterior descending artery branch of right coronary artery.

So the most probable artery to be occluded is right coronary artery.

The possible complication that may arise due to inferior wall myocardial infarction that needs continuous monitoring include :

• ventricular tachycardia or ventricular fibrillation
• cardiogenic shock
• acute mitral valve regurgitation
• acute ventricular septal defect
• bradycardia
• left ventricular aneurysm formation
• right ventricular infarction

2. The conventional 12 lead ECG monitoring is the main diagnostic tool for STEMI. Other electrocardiography includes use of more ECG leads to increase sensitivity of ECG. Continuous ECG is used to record the serial of ECG changes.

Other diagnostic measures include echocardiography, angiography, cardiac MRI and CT scan, measurement of cardiac markers.

3. The inferior wall myocardial infarction can lead to acute pericarditis. Acute pericarditis is the inflammation of the pericardium of heart characterised by sudden onset chest pain and pericardial friction rub.

The patient feels difficulty in breathing while lying flat or swallowing or while moving. This is relieved on leaning forward in seating position.

The most probable cause of patient’s chest pain on day 2 is acute pericarditis.