At the Bedside: Alterations of Systolic Upstroke
An 85-year-old male presents with progressive shortness of breath and pulmonary edema. Initial management with intravenous diuretics leads to symptomatic improvement but is followed by hypotension and poor peripheral perfusion. An arterial line is placed for hemodynamic monitoring. The tracing shows a slurred systolic upstroke, absent dicrotic notch, and narrow pulse pressure. A flush test ensures that the arterial catheter waveform is not artificially dampened. Which of the following best explain the clinical condition associated with this waveform?
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A) Aortic Stenosis
B) Mitral Regurgitation
C) Distributive (Septic) Shock
D) Decompensated Cirrhosis
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Correct Answer: A) Aortic Stenosis
Aortic stenosis classically produces an arterial waveform with a slurred, delayed systolic upstroke (pulsus parvus et tardus) and a narrow pulse pressure. Severe outflow obstruction limits the rate and magnitude of left ventricular ejection, resulting in reduced systolic pressure augmentation and delayed peak systole. In advanced disease, the dicrotic notch may be poorly defined or absent, reflecting reduced stroke volume and altered aortic valve dynamics.
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Incorrect Answer: B) Mitral regurgitation
Why this is incorrect:
Mitral regurgitation typically produces a wide pulse pressure due to increased stroke volume and rapid runoff into the low-pressure left atrium during systole. The arterial waveform often shows a brisk upstroke rather than a delayed or slurred one. While acute severe mitral regurgitation can cause pulmonary edema and hypotension, the arterial waveform does not characteristically demonstrate pulsus parvus et tardus or a narrow pulse pressure. Additionally, the absence of a dicrotic notch is not a defining feature of mitral regurgitation.
Incorrect Answer: C) Distributive (Septic) Shock
Why this is incorrect:
Sepsis is most commonly associated with a hyperdynamic circulation, particularly in early or distributive shock. Arterial waveforms in sepsis typically demonstrate a wide pulse pressure with a rapid systolic upstroke due to low systemic vascular resistance and high cardiac output. While late septic shock may lead to hypotension and poor perfusion, it does not produce the delayed systolic upstroke and narrow pulse pressure seen in fixed outflow obstruction. The waveform described is inconsistent with the vasodilatory physiology of sepsis.
Incorrect Answer: D) Decompensated cirrhosis
Why this is incorrect:
Decompensated cirrhosis is characterized by a hyperdynamic circulatory state, driven by systemic vasodilation and reduced effective arterial blood volume. This typically results in a wide pulse pressure and brisk systolic upstroke, not a delayed one. Although cirrhosis can be associated with hypotension and renal hypoperfusion, the arterial waveform findings described—particularly pulsus parvus et tardus and a narrow pulse pressure—are not characteristic of cirrhotic physiology.