COUPLED VS. UNCOUPLED PERICARDIAL CONSTRAINT - EFFECTS ON CARDIAC CHAMBER INTERACTIONS

The effects of pericardial constraint on cardiac chamber interactions were evaluated by mathematical model analyses based on a novel concept of coupled vs. uncoupled pericardial constraint. We hypothesized that the nature of pericardial constraint can be classified as a ''coupled '' constraint exerted by uniform liquid pressure or an ''uncoupled'' c onstraint exerted by regional surface pressure. The numerical solution of the model of atrioventricular interaction produced the characteris tic waveforms in venous flows and right atrial/ventricular pressures i n classical pericardial diseases. Coupled constraint accounted for the patterns in cardiac tamponade; uncoupled constraint accounted for tho se in constrictive pericarditis. Analytic solution of the model of ven tricular interdependence demonstrated that coupled constraint (tampona de) produced greater gains in ventricular interdependence, increasing the occurrence of pulsus paradoxus, whereas uncoupled constraint (cons triction) produced a greater effective right ventricular elastance, in creasing the likelihood of Kussmaul's sign. Thus the concept of couple d vs. uncoupled constraint may offer a coherent framework to understan d the characteristic steady-state and respiratory-induced hemodynamic events in multiple forms of pericardial diseases.