The effect of ischemia and alterations of heart rate on myocardial potassium balance in man.
TLDR
Myocardial potassium loss was correlated with increments in heart rate and was followed by potassium uptake during the post-pacing period and was closely associated with myocardial lactate production at a ratio of 1 mEq of potassium being lost for each 2 millimoles of lactate produced.Abstract:
Myocardial electrolyte balance and lactate metabolism were studied in 30 patients before, during, and after a period of atrial pacing utilizing a continuous automated sampling technic with simultaneous electrocardiographic and hemodynamic observations. Eight patients with coronary artery disease who had no symptoms during pacing and four normal subjects demonstrated myocardial potassium loss but no abnormalities in lactate metabolism, the electrocardiogram, and hemodynamics during pacing. Myocardial potassium loss was correlated with increments in heart rate and was followed by potassium uptake during the post-pacing period. Eighteen subjects developed angina during pacing associated with hemodynamic and electrocardiographic abnormalities. This ischemic group showed significantly greater myocardial potassium loss during pacing than the non-ischemic group, and this was closely associated with myocardial lactate production at a ratio of 1 mEq of potassium being lost for each 2 millimoles of lactate produced. Increased acidity of coronary sinus blood also accompanied potassium loss during ischemia. No significant changes were seen in sodium balance in either group during the study.read more
Citations
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Dynamics and Consequences of Potassium Shifts in Skeletal Muscle and Heart During Exercise
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TL;DR: It is concluded that despite modifying factors coming into play during muscle activity, the K(+) shifts with high-intensity exercise may contribute substantially to fatigue in skeletal muscle, whereas in the heart, except during ischemia, theK(+) balance is controlled much more effectively.
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TL;DR: The determination of the duration of the pause following cessation of atrial pacing provides a technique for recognition of abnormalities of SAN function.
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References
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Journal ArticleDOI
Ion fluxes in cardiac excitation and contraction and their relation to myocardial contractility.
Journal ArticleDOI
Sequential Alterations in Myocardial Lactate Metabolism, S-T Segments, and Left Ventricular Function During Angina Induced by Atrial Pacing
TL;DR: Abnormalities in myocardial lactate metabolism have been demonstrated with greater regularity during pacing-induced angina than during angina precipitated by exercise or isoproterenol.
Journal ArticleDOI
Reversible Cardiac Failure During Angina Pectoris
TL;DR: It is evident that the ischemic ventricle is operating on a depressed ventricles function curve and this depression of function is reversible following cessation of pacing and can be prevented by the prior administration of nitroglycerin.
Journal ArticleDOI
Electrolyte alterations in acute myocardial ischemic injury.
TL;DR: The data indicate that objective chemical evidence of the death of myocardial cells develops slowly in areas of permanent ischemia primarily because of the reduced flow of blood through the ischemic injured tissue.
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