When does ventricular depolarization occur?

The isoelectric period (ST segment) following the QRS and ending at the beginning of the T wave is the time at which both ventricles are completely depolarized.

What is a ventricular depolarization?

Ventricular depolarization occurs in part via an accessory pathway (AP) directly connecting the atrium and ventricle and thus capable of conducting electrical impulses into the ventricle bypassing the AV-His Purkinje conduction system.

What is the order of depolarization in the heart?

The atrial depolarization spreads to the atrioventricular (AV) node, passes through the bundle of His (not labeled), and then to the Purkinje fibers which make up the left and right bundle branches; subsequently all ventricular muscle becomes activated.

Does the right or left ventricle depolarize first?

The right ventricle will depolarize after the left. The V1 lead is closest to the right ventricle. It will identify depolarization of the right ventricle (current flowing towards the lead) as a positive deflection and left ventricular depolarization (current flowing away from the lead) as a negative deflection.

What happens during depolarization of the heart?

Depolarization of the heart is the orderly passage of electrical current sequentially through the heart muscle, changing it, cell by cell, from the resting polarized state to the depolarized state until the entire heart is depolarized. What is meant by repolarization of the heart muscle?

What causes depolarization of the ventricles?

The AV node slows the impulses from the SA node, firing at a normal rate of 40-60 bpm, and causes depolarization of the ventricular muscle tissue and ventricular contraction. Sympathetic nervous stimulation increases the heart rate, while parasympathetic nervous stimulation decreases the heart rate.

Is depolarization a systole?

The P wave represents depolarization of the atria and is followed by atrial contraction (systole). Atrial systole extends until the QRS complex, at which point, the atria relax. The QRS complex represents depolarization of the ventricles and is followed by ventricular contraction.

Why are 12 leads used for the EKG?

The 12-lead ECG gives a tracing from 12 different “electrical positions” of the heart. Each lead is meant to pick up electrical activity from a different position on the heart muscle. This allows an experienced interpreter to see the heart from many different angles.

What happens when ventricles depolarize?

The atria begin to contract following depolarization of the atria and pump blood into the ventricles. The ventricles begin to contract, raising pressure within the ventricles.

Is depolarization contraction or relaxation?

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 happens to the muscles of the ventricles during depolarization?

Ventricular depolarization is followed by contraction (ventricular systole) and an increase in pressure in the ventricles. Ventricular repolarization causes relaxation of ventricular muscles ( ventricular diastole).

What’s the difference between activation and ventricular repolarization?

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. On the surface ECG, ventricular repolarization components include the J-wave, ST-segment, and T- and U-waves.

When does the period of atrial repolarization occur?

Atrial systole extends until the QRS complex, at which point, the atria relax. The QRS complex represents depolarization of the ventricles and is followed by ventricular contraction. The T wave represents the repolarization of the ventricles and marks the beginning of ventricular relaxation.

What is the difference between depolarization and VR?

Likewise, people ask, what is ventricular depolarization? Ventricular depolarization and activation is represented by the QRS complex, whereas ventricular repolarization (VR) is expressed as the interval from the beginning of the QRS complex to the end of the T wave (QT interval).