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Contraction that squeezes blood towards the exit is more efficient than a simple squeeze from all directions. Although the ventricular stimulus originates from the AV node in the wall separating the atria and ventricles, the Bundle of His conducts the signal to the apex. Depolarization propagates through cardiac muscle very rapidly.
Ventricular relaxation, or diastole, follows repolarization of the ventricles and is represented by the T wave of the ECG. It too is divided into two distinct phases and lasts approximately 430 ms. [1] During the early phase of ventricular diastole, as the ventricular muscle relaxes, pressure on the remaining blood within the ventricle begins ...
It is a form of cardiac arrhythmia in which ectopic foci within either ventricular or atrial myocardium, or from finer branches of the electric transduction system, cause additional beats of the heart. Some medications may worsen the phenomenon. [citation needed] Ectopic beats are considered normal and are not indicative of cardiac pathology.
The ventricular system is continuous with the central canal of the spinal cord from the fourth ventricle, [3] allowing for the flow of CSF to circulate. [ 3 ] [ 4 ] All of the ventricular system and the central canal of the spinal cord are lined with ependyma , a specialised form of epithelium connected by tight junctions that make up the blood ...
Acute occurrence is usually non-life-threatening, but chronic occurrence can progress into tachycardia, [1] bradycardia or ventricular fibrillation. [2] In a normal heart beat rhythm, the SA node usually suppresses the ectopic pacemaker activity due to the higher impulse rate of the SA node.
Ventricular escape beats occur when the rate of electrical discharge reaching the ventricles (normally initiated by the heart's sinoatrial node (SA node), transmitted to the atrioventricular node (AV node), and then further transmitted to the ventricles) falls below the base rate determined by the rate of Phase 4 spontaneous depolarisation of ventricular pacemaker cells. [1]
Percussive pacing, also known as transthoracic mechanical pacing, is the use of the closed fist, usually on the left lower edge of the sternum over the right ventricle in the vena cava, striking from a distance of 20 – 30 cm to induce a ventricular beat (the British Journal of Anaesthesia suggests this must be done to raise the ventricular pressure to 10–15 mmHg to induce electrical activity).
Pre-excitation syndrome is a heart condition in which part of the cardiac ventricles are activated too early. [1] Pre-excitation is caused by an abnormal electrical connection or accessory pathway between or within the cardiac chambers.