What is transmural dispersion of repolarization?
Transmural dispersion of repolarization (TDR) was defined as the difference between the longest and the shortest repolarization times (activation time plus action potential duration (APD) measured at 90% repolarization, APD90) of intracellular APs recorded across the wall (typically M-cell minus epicardial cell …
What is repolarization of the heart?
Repolarization is the return of the ions to their previous resting state, which corresponds with relaxation of the myocardial muscle. 8. Depolarization and repolarization are electrical activities which cause muscular activity.
What does prolonged repolarization mean?
Conclusions Prolonged ventricular repolarization is a risk factor for ischemic heart disease and cardiovascular mortality in subjects with uncomplicated hypertension. Its prognostic significance adds to that of several traditional cardiovascular risk factors, including left ventricular hypertrophy.
What is the repolarization of the ventricles?
Ventricular repolarization is a complex electrical phenomenon which represents a crucial stage in electrical cardiac activity. It is expressed on the surface electrocardiogram by the interval between the start of the QRS complex and the end of the T wave or U wave (QT).
Is repolarization a contraction?
When the electrical signal of a depolarization reaches the contractile cells, they contract. When the repolarization signal reaches the myocardial cells, they relax. Thus, the electrical signals cause the mechanical pumping action of the heart.
What is repolarization of the ventricles?
Why is ventricular repolarization positive?
T and U waves The T wave represents ventricular repolarization. Generally, the T wave exhibits a positive deflection. The reason for this is that the last cells to depolarize in the ventricles are the first to repolarize.
Where does the repolarization of the ventricles occur?
Ventricular depolarization (activation) is depicted by the QRS complex, whereas ventricular repolarization is defined by the interval from the beginning of the QRS complex to the end of the T- or U-wave.
What happens during ventricular diastole?
Ventricular diastole is the period during which the two ventricles are relaxing from the contortions/wringing of contraction, then dilating and filling; atrial diastole is the period during which the two atria likewise are relaxing under suction, dilating, and filling.
What is repolarization phase?
Repolarization is a stage of an action potential in which the cell experiences a decrease of voltage due to the efflux of potassium (K+) ions along its electrochemical gradient. This phase occurs after the cell reaches its highest voltage from depolarization.
Which wave is ventricular repolarization?
The T wave represents the current of rapid phase 3 ventricular repolarization (see diagram above). The polarity of this wave normally follows that of the main QRS deflection in any lead.
Why is S wave negative?
You will also have seen a small negative wave following the large R wave. This is known as an S wave and represents depolarisation in the Purkinje fibres.