A 68-year-old man presents to the emergency department with progressively worsening shortness of breath over the past 2 weeks. He also reports intermittent episodes of lightheadedness and chest heaviness. The patient admits to feeling increasingly fatigued and notes an unintentional 15-lb weight loss over the last 2 months. He denies any fever or recent trauma. He has three-year history of metastatic colon cancer for which he has received multiple rounds of chemotherapy, most recently 3 months ago. His current medications include a multivitamin, ondansetron as needed for nausea, and a proton pump inhibitor. He has a 30-pack-year smoking history and drinks 2-3 glasses of wine on the weekends. Vital signs are temperature 36.7°C (98.1°F), blood pressure 90/64 mmHg, pulse 118 beats/min, and respirations 18/min. On physical examination, the patient appears pale and anxious. Jugular venous distension is noted when the patient lies supine with the torso elevated to 45 degrees. Heart sounds are faint on auscultation, and lung fields demonstrate fine inspiratory crackles bilaterally.
Which of the following additional findings is most likely to be present in this patient?
B) xaggerated fall of blood pressure on inspiration
This patient’s clinical presentation, with progressive shortness of breath, hypotension, tachycardia, and distant heart sounds combined with jugular venous distension, is highly suggestive of cardiac tamponade. In this condition, enough fluid (such as blood or an effusion) accumulates in the pericardial space to cause compression of the heart and reduce cardiac output. Additionally, there is equilibration of diastolic pressures in all four chambers of the heart.
In this patient, the likely etiology of tamponade is his underlying colon cancer, which can lead to pericardial effusion either through direct malignant infiltration or as a paraneoplastic phenomenon. Other common causes of cardiac tamponade include trauma, post-myocardial infarction (e.g., ventricular free wall rupture), complications following cardiac surgery (post-pericardiotomy syndrome), and infections.
A key hemodynamic finding in cardiac tamponade is pulsus paradoxus, a >10 mmHg drop of systolic blood pressure (SBP) on inspiration. In a healthy patient, inspiration causes only a slight reduction in left ventricular stroke volume and hence a physiologic drop in SBP of up to 10 mmHg. In tamponade, this effect is amplified due to the limited cardiac filling, leading to a more significant (>10 mmHg) drop in systolic blood pressure.
Additional supportive findings on electrocardiography (ECG) in cardiac tamponade include low-voltage QRS complexes and electrical alternans, which result from the “swinging” motion of the heart within a large pericardial effusion. Echocardiography classically demonstrates right atrial and right ventricular collapse. The treatment of choice is pericardiocentesis or surgical drainage to relieve the pressure on the heart.
Answer choice A: Biatrial enlargement on echocardiography, is incorrect. Biatrial enlargement is more typically seen in constrictive pericarditis, a chronic condition characterized by a thickened, noncompliant pericardium. It usually occurs as a result of recurrent idiopathic or viral pericarditis, cardiac surgery, radiation therapy, or tuberculous pericarditis.
Answer choice C: Holosystolic murmur that radiates to the axilla, is incorrect. This finding is characteristic of mitral regurgitation, which results from incompetence of the mitral valve. Mitral regurgitation is seen as a complication of myocardial infarction, mitral valve prolapse, and left ventricular dilation. Mitral regurgitation is unrelated to the hemodynamic compromise and pericardial fluid accumulation seen in cardiac tamponade.
Answer choice D: Splitting of second heart sound on expiration, is incorrect. Normally, splitting of the second heart sound (S2) is heard on inspiration. Paradoxical splitting of S2 (split heard on expiration) is most commonly associated with conduction delays, such as those seen in left bundle branch block or in severe aortic stenosis. It is not a feature of cardiac tamponade.
Answer choice E: Weak pulses with a delayed peak, is incorrect. Described as “pulsus parvus et tardus,” this finding is typically associated with aortic stenosis. Aortic stenosis is most commonly seen in older patients with age-related calcification of aortic valves or in younger patients with early-onset calcification of bicuspid aortic valve.
Key Learning Point
Cardiac tamponade is a life-threatening condition resulting from the accumulation of fluid in the pericardial space, leading to reduced cardiac output. It may result from malignancy, trauma, post-myocardial infarction complications, post-cardiac surgery, or infection. Classic findings include hypotension, jugular venous distension, distant heart sounds, and pulsus paradoxus—an exaggerated fall in systolic blood pressure on inspiration. ECG findings such as low-voltage QRS complexes and electrical alternans, along with right atrial and ventricular collapse on echocardiography further support the diagnosis. Pericardiocentesis is the treatment of choice.
