| Popis: |
On a rabbit heart, isolated and perfused, hypocalcic saline (CaCl 2 -0.4 mmole/L.) was used to provoke an electromechanical dissociation, that is, mechanical activity stopped while electrical activity persisted. On these hearts in complete arrest the atrioventricular conduction pathway was cut; as a result a third degree A-V block was recorded. In the two cases reported on, substitution of a normocalcic solution to the hypocalcic one provoked a return to sinus rhythm while the septum had been totally severed as demonstrated by histological examination of case No. 2. In this latter case, the passage to A-V block or sinus rhythm according to whether the perfused solution was hypocalcic or normocalcic occured gradually; all the types of A-V blocks were recorded, in particular a second degree A-V block (Mobitz Type I) while the experimental lesion was distal. The authors discuss these phenomena and in particular the possible role of an extra-Hisian conduction pathway. Further research might lead to useful applications in heart surgery. |
