Comprehensive and Detailed Explanation From Exact Extract:

Constrictive pericarditis is characterized by thickening and fibrosis of the pericardium which restricts diastolic filling of the ventricles. Key echocardiographic features include a characteristic interventricular septal "bounce" or shift during early diastole due to the abrupt cessation of ventricular filling imposed by the rigid pericardium. This septal bounce reflects rapid early diastolic filling followed by a sudden halt as filling pressures equalize, a hallmark of constriction physiology.

Additionally, Doppler studies show marked respiratory variation in mitral and tricuspid inflow velocities (>25%), with an inspiratory increase in tricuspid inflow and a decrease in mitral inflow velocity, reflecting ventricular interdependence caused by the noncompliant pericardium. The mitral inflow typically shows a large E-wave with a small or absent A-wave and a steep deceleration slope, but importantly these velocities vary significantly with respiration, which is not the case in restrictive cardiomyopathy.

Hepatic vein Doppler often reveals a prominent a-wave and a deep y-descent with increased diastolic flow reversal during expiration, indicating elevated right atrial pressures and constrictive physiology.

The inferior vena cava (IVC) is usually dilated and shows no inspiratory collapse (i.e., no normal collapse with sniff test) because of elevated right atrial pressure and impaired venous return.

Therefore:

Option A is incorrect because mitral inflow in constrictive pericarditis shows significant respiratory variation, not absence of it.

Option B is incorrect because the hepatic vein is typically dilated with abnormal flow patterns, not normal size.

Option C is incorrect because the IVC is dilated and does NOT collapse normally with inspiration/sniff in constrictive pericarditis.

Option D is correct because the interventricular septal bounce is a classic feature reflecting ventricular interdependence and constrictive physiology.

These findings are summarized in the "Textbook of Clinical Echocardiography, 6e" (Catherine M. Otto, MD), Chapter 10 (Pericardial Disease), pages 280–285, with key illustrations showing septal bounce, Doppler inflow variations, hepatic vein flow patterns, and IVC findings in constrictive pericarditis. The "Mayo Clinic criteria" for echocardiographic diagnosis also emphasize ventricular septal shift as a critical feature, often combined with tissue Doppler annular velocity patterns and hepatic vein diastolic flow reversal for high diagnostic accuracy.