28. Which of the following right heart catheterization findings would be consistent with an acute ventricular septal defect?

A. Prominent V waves in the pulmonary artery capillary wedge pressure tracing

B. Increased right heart pressures and decreased left heart pressures with inspiration

C. Elevation and equalization of cardiac diastolic pressures

D. An oxygen step-up from the right atrium to the pulmonary artery

E. Prominent V waves in the right atrial pressure tracing

F. Both B and C

With an acute ventricular septal defect, right heart catheterization will show an “oxygen step-up” between the right atrium and right ventricle or pulmonary artery, since oxygenated blood will be present in the right ventricle or pulmonary artery. When infarction of the interventricular septum occurs, this area can thin with the remodeling process and, on occasion, a complete defect between the right and left ventricles can develop. This results in left to right shunting of blood and can be life-threatening when acute. A holosystolic murmur at the left lower sternal border occurs.

The ventricles are good at adapting to hemodynamic stress when gradually introduced, as in slowly worsening aortic regurgitation. However, when acute, ventricular failure and shock occurs, as is present with acute ventricular septal defect (VSD) formation. Emergency surgical repair is warranted in this setting. Without surgical intervention, the mortality rate is > 90%. Fortunately, with the early revascularization techniques now employed (eg, percutaneous coronary intervention), VSD formation is less common.

Choice A describes the findings in acute mitral valve regurgitation. When a large pressure is forced into the left atrium during systole from the mitral regurgitant volume, a large pressure wave is created, which is the V wave. Normal V waves are small; however, it becomes quite large with severe mitral regurgitation. Likewise, choice E describes severe tricuspid regurgitation, which has similar hemodynamics, only translated to the right heart.

Choice B and C describe ventricular interdependence that occurs during cardiac tamponade or constrictive pericarditis. Normally, the pericardium can expand as the heart fills; however, with cardiac tamponade from a large pericardial effusion or constrictive pericarditis, this cannot occur. As a person inspires, venous return is increased to the right heart and the interventricular septum bulges to the left impairing left ventricular filling, reducing left heart cardiac output and thus decreasing systemic pressure (increasing the “pulsus paradoxus”). As a person exhales, right ventricular filling decreases and the left heart fills causing the interventricular septum to bulge to the right impairing right ventricular filling. The diastolic pressures are elevated and equal since every cardiac chamber pressure influences the other since the heart is not able to expand as mentioned above.