Chapter 1 / Clinical Features of Cardiogenic Shock 5
unequivocally evident. In the earlier phases of shock or in less severe circumstances,
these signs may be more subtle. For example, a reduction in urine output or slight con-
fusion may represent a state preceding shock. To complicate matters, in certain shock
states, these signs are characteristically absent. For example, clear lung fields typically
characterize shock resulting from cardiac tamponade or predominantly right ventricu-
lar dysfunction. The signs of shock may also be affected by chronic or current medical
therapy. For example, a patient taking oral β-blockers on a chronic basis may not be
tachycardic during shock, although the heart rate may be much more rapid than in the
basal state. Therefore, it is important to evaluate these signs in the context of the spe-
cific clinical setting.
Additional systemic features may reflect the severity of shock. For example,
prominent jugular venous distention in a patient with shock may indicate severely
increased preload. Peripheral cyanosis may reflect reduced cardiac output and
severely increased peripheral vascular resistance. These signs, however, are usually
not specific to the various etiologies. For example, increased jugular venous disten-
tion may occur as a result of severe left ventricular dysfunction as well as right ven-
tricular dysfunction.
FEATURES BASED ON ETIOLOGY
Systemic signs may be detected that shed light on the etiology of cardiogenic shock,
but not on the severity of the condition. For example, cutaneous manifestations of
infective endocarditis, murmurs of valvular diseases, or murmurs of intracardiac shunts
may be readily appreciated during the physical exam. One should not forget, however,
that a new cardiac condition could complicate an existing cardiac disease (e.g.,
myocardial infarction occurring in a patient with long-standing valvular heart disease).
DIFFERENTIAL DIAGNOSIS
The cardiac patient may also have concomitant noncardiac conditions or may be tak-
ing medications with the potential of adversely affecting the cardiovascular system. For
example, in the elderly patient taking a long list of medications who presents with
fever, severe hypotension, and confusion, and is also found to have cardiac dysfunc-
tion, it may be difficult to assess accurately the contribution of the cardiac dysfunction
to the clinical scenario.
Several noncardiac conditions may cause a state that resembles cardiogenic shock.
These conditions should be considered before making the diagnosis of cardiogenic
shock. For example, pulmonary embolism can severely reduce cardiac output, with
typical clinical features mimicking shock complicating right ventricular infarction such
as jugular venous distention. Aortic dissection as a cause of shock often also poses a
difficult diagnostic challenge; it can cause excruciating chest or back pain, mimicking
the typical anginal pain of acute coronary syndromes. Noncardiac conditions such as
aortic dissection can also involve the heart either initially or eventually. Aortic dissec-
tion, for example, can propagate retrogradely, causing acute aortic regurgitation or
coronary artery dissection.
A thorough physical examination is therefore critical to diagnose cardiogenic shock,
to understand the underlying mechanism for shock, and to exclude noncardiac reasons
for shock. Moreover, findings easily derived from the physical exam are also of prog-
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