Concept of coupled and uncoupled pericardial constraint

Concept of coupled and uncoupled pericardial constraint

Coupled pericardial constraint is exerted by uniform liquid pressure as in cardiac tamponade. Uncoupled pericardial constraint is regional surface pressure as occurs in constrictive pericarditis. Mathematical modeling has shown that coupled pericardial constraint produces greater ventricular interdependence increasing the chance of pulsus paradoxus in cardiac tamponade. Uncoupled pericardial constraint produces a greater right ventricular elastance increasing the likelihood of Kussmaul’s sign [1].

In coupled constraint of pericardial tamponade, uniform liquid pressure is exerted over the entire surface of the heart. This couples changes in volume of one chamber to changes in the volume of all others [2]. In contrast, uncoupled pericardial constraint in constrictive pericarditis is exerted by regional surface pressure which independently restricts changes in the volume of each chamber.

In coupled pericardial constraint of cardiac tamponade, venous flow becomes predominantly systolic and the x descent in right atrial pressure becomes more prominent. In uncoupled pericardial constraint of constrictive pericarditis, venous flow is mainly diastolic and the y descent becomes accentuated.

Greater gains in ventricular interdependence produced by coupled pericardial constraint in cardiac tamponade increases the likelihood of pulsus paradoxus. Greater effective right ventricular elastance produced by uncoupled pericardial constraint in constrictive pericarditis increases the likelihood of Kussmaul’s sign.

Ventricular interdependence is that property of the normal heart in which distension of one ventricle alters the distensibility and filling of the other [3]. Ventricular interdependence is exaggerated in cardiac tamponade when the coupled pericardial constraint limits the total contents in the pericardial sac. Exaggerated reciprocal changes in mitral and tricuspid E wave velocity in cardiac tamponade is a Doppler echocardiographic correlate of reciprocal changes in right and left ventricular filling.

References

1. Takata M, Harasawa Y, Beloucif S, Robotham JL. Coupled vs. uncoupled pericardial constraint: effects on cardiac chamber interactions. J Appl Physiol (1985). 1997 Dec;83(6):1799-813. doi: 10.1152/jappl.1997.83.6.1799. PMID: 9390949.
2. Tyberg JV. Invited editorial on “Coupled vs. uncoupled pericardial constraint: effects on cardiac chamber interactions”. J Appl Physiol (1985). 1997 Dec;83(6):1797-8. doi: 10.1152/jappl.1997.83.6.1797. PMID: 9390948.
3. Shaver JA, Reddy PS, Curtiss EI, Ziady GM, Reddy SC. Noninvasive/invasive correlates of exaggerated ventricular interdependence in cardiac tamponade. J Cardiol. 2001;37 Suppl 1:71-6. PMID: 11433831.