A 78-year-old man with a past history remarkable
only for gout is seen because of the
acute onset of chest pain. He describes a 4-day prodrome of rhinorrhea,
nonproductive
cough, myalgias, and anorexia. Approximately 8 hours before he is seen
in the emergency
room (ER), he began to notice the gradual onset of sharp substernal
chest pain, worse
with inspiration, relieved by sitting up, and associated with diaphoresis.
The pain is slightly worse with exertion but is not relieved by
sublingual nitroglycerin
(NTG) administered in the ER, although morphine sulfate and oxygen
do seem to alleviate
his discomfort. His temperature is 101◦F (38.5◦C), his
heart rate is 105 beats per minute
and regular, his respiratory rate is 17 per minute, and his blood pressure
is 105/65 mmHg.
The remainder of the physical examination is normal. The electrocardiogram
(ECG) is
interpreted by the ER staff to show "sinus tachycardia with ST-segment
elevations inferiorly
and nonspecific ST- and T-wave changes elsewhere." An arterial blood
gas determination
performed on room air shows normal arterial oxygenation. The chest
radiographic study
is normal.
The ER staff starts an IV heparin drip and a platelet glycoprotein
IIb-IIIa inhibitor
infusion for the treatment of a presumed acute coronary syndrome
(ACS) An IV
NTG infusion and oxygen therapy are instituted but, despite these
measures, the pain
continues. The cardiac catheterization team is called to consider
coronary angiography.
Antacid therapy does not relieve the pain and only morphine sulfate
seems to offer relief.
Blood tests reveal a normal troponin, normal electrolytes, normal
D-dimer, and normal
renal function. The hemoglobin is normal but the white blood cell
count is mildly elevated.
The patient is taken to the catheterization laboratory and his coronary
angiogram
reveals diffuse, mild, nonobstructive coronary artery disease (CAD).
The IIb-IIIa inhibitor AQ3
is discontinued. When the patient is transferred to the coronary
care unit, the ECG shows
continued "evolution'' with ST-segment elevations of less than 2
mm in leads I, II, III, aVL,
aVF, and V2 to V6 that do not respond to IV NTG. The patient's chest
pain persists.
Further increments of NTG are given in an IV infusion and the patient's
blood pressure
begins to decrease. After 2 hours, the patient continues to writhe
in pain, complains of
feeling dizzy and having a severe headache, and vomits after the
fifth dose of IV morphine
sulfate. You are asked to see the patient and your examination reveals
sinus tachycardia,
a blood pressure of 82/50 mmHg (no pulsus paradoxus), a respiratory
rate of 16 per
minute, a temperature of 101◦F (38.5◦C), clear lung fields,
and no elevation in the
jugular venous pressure, but a three-component pericardial friction
rub is heard over the
precordium. The hemoglobin level is stable.
- What is the most likely clinical diagnosis of this patient's
chest pain?
- On the basis of your clinical impression of this patient's presentation,
what features
would be expected on the ECG?
- Is a normal troponin helpful in acute MI?
- What is the most effective treatment for acute pericarditis?
- What is the most likely cause of the hypotension in this patient?
Read the discussion
from Internal Medicine Casebook,
3e
Robert W Schrier MD
ISBN: 978-0-7817-6529-9 |
