The Conduction System of the Swine Heart (1)
The swine has often been used as an experimental model for ischemic heart disease and sudden death. The anatomy of the conduction system, however, has been infrequently studied. Therefore, it seemed appropriate to delineate the course of the conduction system in this animal and compare it with that of a man. birth control yasmin
Material and Methods
Five pigs ranging in weight from 30 to 40 kg and from 10 to 15 weeks of age were studied. The animals were sedated with ketamine 15 to 20 mg intramuscularly (IM), and then intubated. They were fully ventilated on room air (tidal volume, 10 ml/kg) and light anesthesia maintained using 0.25 to 0.75 percent halothane, to effect. Routine electrophysiologic studies were performed according to the methods outlined by Gillette and Garson. Quadripolar catheters were inserted percutaneously from the right and left groins and positioned at the superior vena cava-right atrial junction and across the tricuspid valve for pacing and intracardiac recording (Fig 1). Pacing was performed using a pacemaker (Grass S-88) with a custom-built programmable timing device. Intracardiac recordings were obtained on an eight-channel recorder (Beckman R612). Six hearts of various ages were compared with adult human hearts at a gross level and the conduction systems of two of the pig hearts were examined in the following manner.
Figure 1. His bundle recording of the pig. Intervals: HRA-LRA = 10 ms; LRA-H = 65 ms; H-V = 25 ms. HRA = high right atrium; HBE = His bundle electrocardiogram; A = atrial wave; H = His bundle spike; V = ventricular wave; and LRA = low right atrium.