Standardization of an experimental model of parabiotic isolated heart in rabbits

Abstract

The objective was to standardize an experimental model of parabiotic isolated heart in rabbits, testing their stability and durability for use in cardiovascular research. Sixty-six Norfolk-2000 rabbits were used and divided in 2 groups: donors of the isolated heart and support animals, in a total of 33 preparations. Circulatory support for the isolated heart was established with the aid of peristaltic pumps and the flow was kept constant (16ml/min.). An intraventricular balloon was inserted in the left ventriculum, and was adjusted to produce diastolic pressure of ± 10mmHg. Heart rate was established at 120 beats per minute with the use of a pacemaker. Hemodynamic, laboratory and histopathological parameters were evaluated. Of the 33 preparations, 13 were excluded according to preestablished criteria. Of the 20 remaining preparations, 10 completed the maximum protocol time (180 minutes). There was progressive hemodynamic deterioration with decrease of mean blood pressure (89.30±6.09mmHg->47.50±6.35mmHg) in the support animal. There was hemodynamic stability of the isolated heart for the 10 preparations that completed the 180 minutes of the protocol. Laboratory parameters showed progressive decrease of sodium, potassium and hemoglobin, which is compatible with hemodilution. Histopathology showed greater distance among the fibers, compatible with edema. The present model showed 100% stability and activity of the preparations within 60 minutes, and 50% of the active preparations were progressively lost within 180 minutes. The present model is viable for cardiovascular research.