Continuous monitoring of right ventricular volume changes using a conductance catheter in the rabbit.
To assess the reliability of conductance (G) catheter for evaluating right ventricular (RV) volume changes, a miniature (3.5F) six-electrode catheter was developed and tested in 11 New Zealand rabbit hearts. In five animals the heart was excised; in six it was left in the thorax. RV conductance was recorded while the RV was filled with blood in 0.25-ml steps at different left ventricular (LV) volumes. Linear correlation of measured conductance vs. reference volumes was computed. RV conductance was highly correlated with reference volume [correlation coefficient (r) ranging from 0.991 to 0.999]. Slope of regression lines was not significantly affected by LV volume variations in 1-ml steps or by acute conductance changes of structures surrounding the heart, whereas the intercept was affected only by the 0- to 1-ml LV volume change. In four rabbits, RV conductance changes during a cardiac cycle [stroke volume- (SV) G] were compared in vivo with electromagnetic flow probe-derived estimates of SV (SVem) as stroke volume was varied by graded inferior vena caval occlusion. SV-G correlated well with SVem (r ranging from 0.92 to 0.96). This correlation persisted after the thorax was filled with saline; however, significant differences were found in individual slopes (P < 0.001). These results show that the conductance catheter has a potential to reliably monitor in vivo relative RV volume changes in small-animal hearts.
Soldà
P L
PL
Department of Internal Medicine, University of Pavia, Italy.
Pantaleo
P
P
Perlini
S
S
Calciati
A
A
Finardi
G
G
Pinsky
M R
MR
Bernardi
L
L
D000758:Anesthesia; D000818:Animals; D006328:Cardiac Catheterization; D004553:Electric Conductivity; D004562:Electrocardiography; D066298:In Vitro Techniques; D011817:Rabbits; D013318:Stroke Volume / Q000502:physiology; D016278:Ventricular Function, Right / Q000502:physiology*