A 64-year-old man comes to the emergency department due to worsening dizziness and shortness of breath for the past several days. The patient was diagnosed with advanced stage lung cancer 6 months ago and is receiving palliative care. The patient has no other medical history. Blood pressure is 85/45 mm Hg, pulse is 122/min and regular, and respirations are 22/min. Pulse oximetry is 94% on room air. There are undulations in blood pressure at different phases of respiration. On physical examination, the point of maximal impulse is not palpable, and heart sounds are distant. Chest x-ray reveals diffuse pulmonary metastatic disease and new enlargement of the cardiac silhouette. Which of the following hemodynamic changes are most likely present in this patient due to his current cardiac condition?

Question

Quizplus · Accepted Answer

11ec160b_3a82_459f_9249_f7b367c67e59_MD0001_00 This patient's hypotension, distant heart sounds, and new enlargement of the cardiac silhouette on chest x-ray in the setting of advanced malignancy are consistent with cardiac tamponade. Cardiac tamponade results from an accumulation of fluid within the relatively noncompliant pericardium, leading to an increase in pericardial pressure. The increased pericardial pressure compresses the relatively low-pressure, right-sided heart chambers and restricts diastolic filling of the right side of the heart to cause obstructive shock. In addition to Beck's triad (ie, hypotension, distant heart sounds, jugular venous distension), other common signs of tamponade include an absent point of maximum impulse and pulsus paradoxus (ie, >10 mm Hg drop in systolic blood pressure with inspiration). In tamponade, the compressed right atrium is decreased in size, and elevated right atrial pressures are transmitted backward to the vena cava, causing increased central venous pressure. With decreased right-sided filling, less blood is pumped through the pulmonary circulation to the left atrium and left ventricle, resulting in decreased stroke volume and cardiac output (and causing hypotension and shock). Although the volume of blood reaching the left atrium is reduced, left atrial pressure is increased due to external compression by the excessive pericardial fluid (Choices A, B, C, and E). As tamponade progresses, diastolic pressures in all 4 cardiac chambers (ie, right atrium, right ventricle, left atrium [estimated by pulmonary capillary wedge pressure], left ventricle) increase and equalize with pericardial pressure (and with one another), eliminating the normal pressure gradients and stagnating blood flow within the heart. Educational objective: Cardiac tamponade involves increased pericardial pressure that restricts diastolic filling of the right-sided heart chambers, leading to obstructive shock with increased central venous pressure and decreased stroke volume and cardiac output. As tamponade progresses, diastolic pressures in all 4 cardiac chambers increase and equalize with pericardial pressure (and with one another), stagnating blood flow within the heart.

A 64-Year-Old Man Comes to the Emergency Department Due to Worsening