Ventricular interdependence (or ventricular coupling) is a phenomenon whereby the function of one ventricle is altered by changes in the filling of the other ventricle. This leads to a volume increase of one ventricle associated with a decreased volume in the opposite ventricle 1.
This condition is classically seen in constrictive pericarditis (called the septal bounce sign). In constrictive pericarditis, the thickened, fibrotic, and/or calcified non-compliant pericardium results in a fixed volume of the pericardial sac. The position of the interventricular septum depends on the relative pressure differences between the left ventricle (LV) and the right ventricle (RV) throughout the cardiac cycle and is also influenced by respiration.
During early diastole, there is rapid inflow of blood into the ventricles which causes a marked change in ventricular pressures. Because right ventricular filling begins slightly before left ventricular filling, the change in pressure equates to the paradoxical leftward motion of the interventricular septum 2. This phenomenon of ventricular interdependence leads to abnormal septal motion, called paradoxical septal motion or septal bounce. The septal bounce is accentuated during inspiration because of lower intrathoracic pressures when venous return to the right ventricle increases. This effect is reversed during exhalation when less blood is returned to the right ventricle 3. This phenomenon is also seen in cardiac tamponade, pulmonary hypertension, left bundle branch block, and right ventricular pacing 1.
History and etymology
A hypothesis of the ventricular interdependence concept was first made in 1910 by the French physiologist Hippolyte Marie Bernheim (1840-1919) subsequently also known as the 'Bernstein phenomenon'. He described a small series of patients with signs and symptoms of right heart failure where an autopsy revealed left ventricular hypertrophy with the septum protruding into the right ventricular cavity 4,5.
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