Related Experiment Video
Updated: Aug 5, 2026
07:58
Induction and Assessment of Ischemia-reperfusion Injury in Langendorff-perfused Rat Hearts
Published on: July 27, 2015
Repolarisation and refractoriness during early ischaemia in humans
P M Sutton1, P Taggart, T Opthof
1The Hatter Institute, Department of Cardiology, University College London Hospitals, Grafton Way, London WC1E 6DB, UK. peter.sutton@ucl.ac.uk
Heart (British Cardiac Society)
|September 20, 2000
Summary
During early ischemia, effective refractory period (ERP) lengthens while action potential duration (APD) shortens in patients with coronary artery disease. This dissociation impacts arrhythmogenesis.
Area of Science:
- Cardiovascular Physiology
- Cardiac Electrophysiology
- Ischemic Heart Disease
Background:
- The effective refractory period (ERP) and action potential duration (APD) are critical determinants of cardiac electrical stability.
- Understanding their behavior during acute ischemia is vital for managing arrhythmias in patients with coronary artery disease.
Purpose of the Study:
- To investigate changes in human ventricular ERP during the initial minutes of global ischemia.
- To examine the relationship between ERP and APD during this ischemic period.
Main Methods:
- Monophasic action potential duration (MAPD) and ERP were measured in 26 patients undergoing cardiac surgery.
- Ischemia was induced via aortic cross-clamping for three minutes.
- ERP was assessed using the extrastimulus technique at varying stimulus strengths.
Main Results:
- Mean ERP significantly lengthened after three minutes of ischemia in both low and high stimulus groups.
- MAPD significantly shortened during ischemia, independent of stimulus strength.
- The correlation between ERP and APD deteriorated significantly within one minute of ischemia.
Conclusions:
- Global ischemia in patients with coronary artery disease leads to an increase in ERP and a decrease in APD.
- The dissociation between ERP and APD during early ischemia suggests a shift towards post-repolarization refractoriness.
- These electrophysiological changes may contribute to the arrhythmogenesis observed in acute ischemic events.
Related Concept Videos
01:30Cardiac Action Potential
Cardiac action potentials are essential for proper heart function, enabling the rhythmic contractions needed for adequate blood circulation. Nodal cells and Purkinje fibers, specialized for electrical conduction, generate these action potentials.
The cardiac action potential process involves a series of phases characterized by the movement of ions across the cardiac cell membranes, leading to the depolarization and repolarization of the cardiac myocytes.
Ionic Basis of Cardiac Action Potentials
The cardiac action potential process involves a series of phases characterized by the movement of ions across the cardiac cell membranes, leading to the depolarization and repolarization of the cardiac myocytes.
Ionic Basis of Cardiac Action Potentials
01:15Ischemic Stroke ll: Pathophysiology
An ischemic stroke occurs when a cerebral blood vessel becomes obstructed, most often by a thrombus or embolus, interrupting the delivery of oxygen and glucose to brain tissue. Because neurons rely on continuous aerobic metabolism, energy failure begins within minutes of reduced perfusion. The region receiving the least blood flow becomes the infarct core, an area of irreversible cellular death. Surrounding this core lies the penumbra, a zone of hypoperfused but still viable tissue that is...