Key Points
- To explore how changes in ventricular activation affect R-wave amplitude on ECG during acute myocardial ischemia.
- Studied nine open-chest dogs during myocardial ischemia induced by left circumflex coronary artery occlusion.
- Measured R-wave amplitude changes in various ECG leads and correlated them with intramyocardial conduction times and hemodynamics.
- Analyzed changes in left ventricular dimensions and cardiac output before and after occlusion.
- In the first 30 seconds post-artery ligation, intramyocardial conduction time increased by 11.3% above control (p < 0.001), followed by a ZRWA decrease of 16.8% below control (p < 0.001).
- A subsequent phase showed intramyocardial conduction slowing to 135.1% above control (p < 0.001) while 2RWA increased by 53.1% above control (p < 0.001).
- Conduction time along the specialized conduction system showed no significant changes.
Structured PICO
PPopulation9 open-chest dogs
IInterventionAcute myocardial ischemia induced by one-stage occlusion of the left circumflex coronary artery
CComparatorBaseline (control) before occlusion
OOutcomeRelationship between changes in the sum of R-wave amplitude (ZRWA) and intramyocardial conduction timessurrogate
During acute myocardial ischemia, changes in R-wave amplitude on the surface ECG are closely correlated with a biphasic pattern of intramyocardial conduction changes.