In cardiac tamponade (T) right atrial (RA) essentially equals intrapericardial pressure (IPP) so that transmural LV filling pressure may be estimated as pulmonary wedge (PW) minus RA. Although exact equality of mean RA and PW is sought in T, the respiratory variation in LV filling underlying pusus paradoxus would suggest variation in instantaneous (PW-RA). Simultaneous PW and RA were measured in 8 T pts, along with IPP, arterial pressure (AP), heart rate (HR), and cardiac output (CO), during T and after pericardiocentesis (P) of 710±500 ml.
Results: RA(mm) PW(mm) IPP(mm) AP(mm) HR(/min) CO(L/min) T 15±3 18±4 14±3 97±22 95±25 5.2±1.7 P 8±3 10±3 2±2 89±29 89±29 7.1±2.0 P <0.001 <0.01 <0.001 ns ns <0.01
The difference in RA and PW means during T was significant (p<0.001). pulsus decrased from 19±5 to 9±5 mm with p, (<0.001). expiratory (pw-ra) was 6±2 mm while inspiratory decrase in oipp was 5±3 mm, less than the normal 8-10 mm decrease in intrathoracic pressure.
Conclusion: In tamponade (1) diastolic equalization of PW and RA is predominantly inspiratory; (2) a decrease in (PW-RA) with inspiration while transpericardial pressure increases suggests direct right-left diastolic competition.
Boltwood C, Rieders D, Gregory KW, Shah P, "Inspiratory tracking sign in pericardial disease," Circulation (Suppl.II) 70:11-103, 1984.