Continuous coronary venous K+ monitoring ([K+]gcv) reflected increases in extracellular K+ during ischemia (from 3.87 to 4.84 mM), serving as a sensitive marker except at very low coronary flow.
Does continuous coronary venous K+ monitoring accurately reflect extracellular myocardial K+ accumulation during myocardial ischemia in a swine model?
Coronary venous K+ monitoring is a sensitive marker for detecting early myocardial ischemia, though it loses accuracy at very low coronary flow rates.
Background: Myocardial ischemia causes accumulation of extracellular myocardial K+ (K+e). However, the relation between K+e, and local coronary venous K+, i.e., K+ in the great coronary vein (K+gcv) has not been established. To determine the sensitivity of K+gcv as a marker of myocardial ischemia, we continuously measured K+e, using intramyocardial K+-selective plunge electrodes, and K+gcv, using a catheter-tip K+ electrode inserted into the great cardiac vein, during two types of ischemia. Methods and Results: In in-situ pig hearts, ischemia was induced by implementing a progressive decrease in carotid-to-left anterior descending artery (LAD) shunt flow from 40 to 0 mL/min at constant heart rate (100-130/min) and a progressive increase in heart rate from 100 to 160 beats/min at the threshold flow. The progressive decrease in LAD flow to 5 mL/min caused parallel increases in K+e (from 3.87 ± 0.37 to 8.65 ± 1.13 mM) and K+gcv (from 3.87 ± 0.37 to 4.84 ± 0.43 mM). However, below 5 mL/min, K+gcv failed to reflect the increase in K+e and often decreased. The progressive increase in heart rate at the threshold flow caused parallel changes in K+e (from 4.08 ± 0.36 to 4.87 ± 0.14 mM, n = 3) and K+gcv (from 3.08 ± 0.42 to 4.18 ± 0.43 mM). The verapamil- and propranolol-induced changes in K+e during low-flow ischemia were reflected by changes in K+gcv. Conclusions: Change in K+gcv is a sensitive marker of myocardial ischemia, except at very low coronary flow. Thus, K+gcv can be used to detect early myocardial ischemia.
Watanabe et al. (Sun,) conducted a other in Myocardial ischemia. Continuous coronary venous K+ monitoring vs. Extracellular myocardial K+ monitoring was evaluated on Sensitivity of [K+]gcv as a marker of myocardial ischemia. Continuous coronary venous K+ monitoring ([K+]gcv) reflected increases in extracellular K+ during ischemia (from 3.87 to 4.84 mM), serving as a sensitive marker except at very low coronary flow.