When an atrial contraction occurs, pacing stimulation is delivered to the LV upon expiration of a predetermined A-LV delay interval.

These can start in the upper or lower chambers of the heart (atrial or ventricular premature contractions).

The medical device preferably paces the ventricles in response to detected electrical activity in the atria indicative of atrial contraction.

The diastole has four phases: isovolumetric relaxation, rapid filling, diastasis, and atrial contraction.

If proper mechanical coupling is determined to not exist, an additional atrial contraction is induced within the same ventricular cycle to maintain atrial-ventricular mechanical coupling.

S4 is heard in late diastole and represents ventricular filling due to atrial contraction in the presence of a stiff ventricle.

The pulsation generator shifts gradually, which on the cardiogram looks like various modifications of the P wave, reflecting atrial contraction.[19]

Increased late diastolic filling is due to increased atrial contraction, and there is increased atrial size.

The A-H delay can be used by an electrostimulation energy delivery control circuit (212) for specifying timing between a paced or sensed atrial contraction and a His -bundle pacing time.

at atrial fibrillation there is a chaotic contraction of the atria.

The muscle mass assisting the atria is then stimulated at the same time as contraction of the atrial myocardium.

When an atrial contraction occurs, pacing stimulation is delivered to the LV upon expiration of a predetermined A-LV delay interval.

These can start in the upper or lower chambers of the heart (atrial or ventricular premature contractions).

The medical device preferably paces the ventricles in response to detected electrical activity in the atria indicative of atrial contraction.

Irregular heartbeat caused by very rapid contraction of the top two chambers of the heart (atrial fibrillation)