Chapter 27. Cardiovascular Diseases
A 70-year-old woman presents to the emergency department with sudden-onset chest and upper back pain and was found to have a type B aortic dissection for which she is being medically managed in the intensive care unit with close hemodynamic monitoring. She initially arrived with hypertension and tachycardia but has now become hypotensive. Bedside transthoracic echocardiogram is shown below. Which of the following is true regarding cardiac tamponade?
A. Pericardial fluid volume is predictive of clinical hemodynamic status.
B. Pericardiocentesis is indicated in all cases of cardiac tamponade.
C. Echocardiographic evidence of diastolic right atrial collapse is a specific finding of tamponade physiology.
D. Echocardiographic evidence that the inferior vena cava (IVC) fails to collapse during spontaneous respiration is a specific finding of tamponade physiology.
E. Intrapericardial pressure increases exponentially as pericardial fluid volume increases.
E. Point-of-care ultrasound is the modality of choice to quickly and safely evaluate patients with suspected tamponade physiology. Cardiac tamponade occurs when pericardial fluid disturbs cardiac function leading to decreased cardiac output and, in severe situations, complete hemodynamic collapse. Echocardiographic evidence of cardiac tamponade is characterized by collapse of the right atrium and ventricle during diastole. Right atrial collapse is not a specific finding for cardiac tamponade as it may also be found in patients with pleural effusions and severe dehydration. Failure of the IVC to collapse with respirations may be found in cardiac tamponade, but is also found in patients who have elevated right-sided pressures due to volume overload, pulmonary embolism, or valvular heart disease. Estimation of pericardial fluid volume is not generally predictive of clinical hemodynamic compromise as chronic pericardial effusions may expand the pericardium over time and not lead to significant tamponade. The concern in this patient is a type B dissection extending proximally into the ascending aorta leading to a retro type A dissection. Pericardiocentesis should be used with caution in cardiac tamponade secondary to aortic dissection, and the preference is for definitive surgical management. The correct answer is choice E as pericardial fluid has an exponential pressure-volume relationship.
A 65-year-old man with past hypertension, hyperlipidemia, peripheral vascular disease, and extensive tobacco use who underwent femoral-femoral bypass grafting was found to have ST-segment elevations upon emergence of anesthesia and was taken urgently for cardiac catheterization. Compared to acute coronary syndromes in the nonsurgical population, which of the following best describes perioperative myocardial infarctions?
A. Perioperative myocardial infarctions are more likely to be associated with acute plaque rupture rather than supply-demand mismatch.
B. Perioperative myocardial infarction is more likely to ...