Prehospital ECG with ST-depression and T-wave inversion are associated with new onset heart failure in individuals transported by ambulance for suspected acute coronary syndrome.

Background: Prehospital electrocardiogram(s) (ECG) can improve early detection of acute coronary syndrome (ST-segment elevation myocardial infarction [STEMI], non-STEMI, and unstable angina) and inform prehospital activation of cardiac catheterization lab; thus, reducing total ischemic time and improving patient outcomes. Less is known, however, about the association of prehospital ECG ischemic findings and long term adverse clinical events. With this in mind, this study was designed to examine the: 1) frequency of prehospital ECGs for acute myocardial ischemia (ST-elevation, ST-depression, and/or T-wave inversion); and, 2) whether any of these specific ECG features are associated with adverse clinical events within 30 day of initial presentation to the emergency department (ED).

Effects of Verapamil and Pinacidil on Extracellular K, pH, and the Incidence of Ventricular Fibrillation during 60 Minutes of Ischemia.

Ca-channel antagonist verapamil and ATP-sensitive K-channel opener pinacidil are known to decrease the rise in extracellular K ([K]) level and pH (pH) that occurs during reversible acute myocardial ischemia and to lessen the accompanying activation delay. Verapamil is also known to decrease the incidence of ventricular tachycardia (VT)/fibrillation (VF) during acute myocardial ischemia; however, the effects of ATP-sensitive K-channel opener on the incidence of VT/VF are controversial. We studied, in an in vivo pig model, the effects of verapamil and pinacidil on the changes in [K] level and pH, local activation, and the incidence of VT/VF during 60 minutes of ischemia.

Effects of Propranolol and Verapamil on Changes in TQ and ST Segment Potentials During Graded Coronary Flow Reduction in a Porcine Myocardial Ischemia Model.

Acute myocardial ischemia causes TQ depression and ST elevation. However, the effects of cardioprotective drugs such as β-blockers and Ca-antagonists on the extent of TQ depression, ST elevation, and myocardial ischemic injury are not fully understood.We created a carotid-coronary shunt in 30 pigs, and extracellular K ([K]), TQ, and ST segments were recorded simultaneously with K-selective plunge electrodes placed in the left anterior descending artery (LAD) distribution during graded LAD flow reduction before and after administration of propranolol or verapamil.

Initial and Secondary ST-T Alternans During Acute Myocardial Ischemia in the In-Situ Pig Heart.

The factors responsible for the ST-T wave alternans (STTA) and associated arrhythmias during acute ischemia have not been clarified.In acutely ischemic porcine myocardium, we recorded transmural unipolar and bipolar electrocardiograms and mid-myocardial extracellular K(+) ([K(+)]e) from the center of the ischemic zone during 8-minute episodes of ischemia. Two different STTAs occurred.