Anesthetics and automaticity in latent pacemaker fibers. IV. Effects of isoflurane and epinephrine or norepinephrine on automaticity of dominant and subsidiary atrial pacemakers in the canine heart. Anesthesiology 1993 Sep;79(3):555-62
Date
09/01/1993Pubmed ID
8363082Scopus ID
2-s2.0-0027194275 (requires institutional sign-in at Scopus site) 3 CitationsAbstract
BACKGROUND: Anesthesia and surgery may be associated with atrioventricular junctional or ventricular rhythm disturbances. These may be caused by alteration of automaticity of primary and subsidiary pacemakers.
METHODS: The direct effects of isoflurane, alone or in combination with epinephrine (E) and norepinephrine (NE), as well as single effects of E and NE, were examined on automaticity of primary and subsidiary atrial pacemakers (SAP) using a perfused canine right atrial preparation (n = 29). Preparations were perfused with oxygenated Krebs' solution at a constant perfusion pressure of 87 mmHg and a temperature of 36.5 +/- 0.5 degrees C. Delivered concentrations of isoflurane of 1.4 and 2.8% corresponded to measured perfusate concentrations of 315 +/- 7 and 617 +/- 16 microM in experiments with E (n = 14), and 316 +/- 10 and 610 +/- 26 microM in experiments with NE (n = 15). Epinephrine or NE perfusate concentrations were 2 and 5 micrograms/l or 5 and 10 micrograms/l, respectively. To determine the site of earliest activation, extracellular recordings were made from the SA node region and distal sites (approximately 1, 2, and 3 cm) along the sulcus terminalis, the previously reported locations of SAP. Sites of earliest activation shifts from SA node to SAP were scored 1, 2, or 3 depending on the distance from the control pacemaker. The summed shift scores (magnitude score) were normalized by dividing by the total number of preparations for each experimental condition.
RESULTS: Exposure to isoflurane, NE, or E alone did not produce a significant increase in the incidence of pacemaker shifts or normalized pacemaker shift scores. Only the high dose of E significantly increased the incidence of pacemaker shifts and normalized shift scores. Dysrhythmogenic potential of E and NE tended to be greater after earlier exposure to isoflurane. Every combination of isoflurane with E or NE produced a significant increase in the incidence of pacemaker shifts and normalized shift scores.
CONCLUSIONS: It was concluded that isoflurane with E or NE acts synergistically to increase dysrhythmic potential in the arterial tissue.
Author List
Boban M, Atlee JL 3rd, Vicenzi M, Kampine JP, Bosnjak ZJMESH terms used to index this publication - Major topics in bold
AnimalsDogs
Epinephrine
Female
In Vitro Techniques
Isoflurane
Male
Norepinephrine
Sinoatrial Node