accp-seek board review question of the month

A 78-year-old
accp-seek board review question
of the month
ICU Admission for Anterior Myocardial
Infarction With Shortness of Breath*
Steven M. Hollenberg, MD, FCCP
(CHEST 2004; 125:1577–1578)
woman is admitted to the ICU with
an anterior myocardial infarction. She is treated
with aspirin, thrombolytic therapy, and nitrates. Her
clinical course is uneventful until the third hospital
day, when she has sudden onset of shortness of
breath. Her BP is 95/55 mm Hg, pulse rate is 124
beats/min, and respiratory rate is 32 breaths/min.
Cardiovascular examination reveals jugular venous
*From the ACCP-SEEK program, reprinted with permission.
Items are selected by Department Editors Richard S. Irwin, MD,
FCCP, and John G. Weg, MD, FCCP. For additional information,
phone 1-847-498-1400.
Reproduction of this article is prohibited without written permission
from the American College of Chest Physicians (e-mail:
permissions@chestnet.org).
Correspondence to: Steven M. Hollenberg, MD, FCCP, Cooper
Hospital, Division of Cardiology, 366 Dorrance, One Cooper
Plaza, Camden, NJ 08103; e-mail: hollenberg-steven@
cooperhealth.edu
distention, soft heart sounds, and a pansystolic murmur.
She has bibasilar crackles. A chest radiograph
shows pulmonary edema. Her ECG shows sinus
tachycardia and an evolving anterior myocardial infarction.
A pulmonary artery catheter is inserted, and
the following readings are obtained: right atrium
pressure, 6 mm Hg (56% O 2 saturation); right
ventricular pressure, 40/6 mm Hg (55% O 2 saturation);
pulmonary artery pressure, 40/23 mm Hg
(mean, 30 mm Hg; 57% O 2 saturation); pulmonary
artery occlusion pressure, 24 mm Hg (v waves to 40);
and cardiac output, 3.5 L/min. Which of the following
is most appropriate at this time?
A. Pericardiocentesis
B. Mitral value surgery
C. Repeat thrombolytic therapy
D. Cardiac catheterization and angioplasty
E. Surgical repair of the ventricular septum
www.chestjournal.org CHEST / 125 /4/APRIL, 2004 1577

Answer: B. Mitral value surgery
Acute mitral regurgitation after myocardial infarction
presents with pulmonary edema and cardiogenic
shock. The presence of a new holosystolic murmur,
along with a large v wave on the pulmonary artery
occlusion tracing, is diagnostic of this complication.
Ischemic mitral regurgitation is more commonly associated
with inferior myocardial infarction and ischemia
or infarction of the posterior papillary muscle, but can
occur with anterior infarction, particularly in patients
with multivessel disease. In the presence of cardiogenic
shock, the pansystolic murmur can be soft or inaudible
above the pulmonary edema, and may be limited to
early systole because of rapid equalization of pressures
in the left atrium and left ventricle.
Rupture of the interventricular septum can be
difficult to distinguish clinically from acute mitral
regurgitation due to papillary muscle rupture; in
both, patients have a systolic murmur, and large v
waves in the pulmonary artery occlusion tracing may
be seen with septal rupture due to high pulmonary
flow. With septal rupture, however, there is a step-up in
oxygenation from the right atrium to the right ventricle
of 5% due to left-to-right shunting. Because there is
no step-up in the patient described in this question,
option E is incorrect. Pump failure due to reocclusion
of the infarct artery is a possible cause of cardiogenic
shock after myocardial infarction, but most cases of
shock due to pump failure develop in the first 24 h, and
neither the v wave nor the murmur is characteristic.
Thus, options C and D, measures to re-establish pa-
Figure 1. Echocardiographic image of a ruptured papillary muscle.
tency of an occluded artery, are incorrect. Pericardial
tamponade (option A) can result from rupture of the
left ventricular free wall and lead to shock after myocardial
infarction, but the hemodynamic profile is
characterized by elevation and equalization of intracardiac
pressure not seen in our patient.
Echocardiography is often useful to diagnose
acute mitral regurgitation after myocardial infarction,
and can rule out other causes of acute decompensation
such as free wall rupture, tamponade, and
pump failure. An echocardiographic image of a
ruptured papillary muscle is shown in the accompanying
Figure 1 (arrow). Management includes afterload
reduction with nitroprusside and intra-aortic
balloon pumping as temporizing measures. Inotropic
or vasopressor therapy may be needed to support
cardiac output and BP. Definitive therapy, however,
is surgical valve repair or replacement, which should
be undertaken as soon as possible because clinical
deterioration can be sudden.
Selected Readings
Bolooki H. Emergency cardiac procedures in patients in cardiogenic
shock due to complications of coronary artery disease.
Circulation 1989; 79: I-137–I-148
Hollenberg SM, Kavinsky CJ, Parrillo JE. Cardiogenic shock.
Ann Intern Med 1999; 131:47–59
Khan SS, Gray RJ. Valvular emergencies. Cardiol Clin 1991;
9:689–709
Meister SG, Helfant RH. Rapid bedside differentiation of ruptured
interventricular septum from acute mitral insufficiency.
N Engl J Med 1972; 287:1024–1025
1578 ACCP-SEEK Board Review Question of the Month