Electrical Conduction System, ECGs & Arrhythmias

Basic EPU Lessons 3 and 4

What does the “lub” sound correspond to?

Ventricular systole (contraction)

What does the “dub” sound correspond to?

Ventricular diastole (relaxation)

What part of the normal conduction pathway activates the left atria?

Through Bachman’s bundle

Which side of the heart is least forgiving to clots and why?

The left side, because it pumps out to the aorta which branches to the carotid arteries, increasing risk of stroke

What side is more forgiving of clots and why?

The right side, because the pulmonary capillaries act as effective filters for blood clots

Cardiac tamponade

rapid/excessive buildup of blood, fluid or pus in the pericardial sac that squeezes the heart and prevents proper filling

when might an epicardial ablation be necessary?

When an endocardial ablation lesion is not deep enough to reach the target tissue

Where are common triggers of atrial fibrillation (AF)?

the pulmonary veins

Why were balloon-based ablation solutions developed?

Because the pulmonary vein openings are irregular

Do all cardiac cells have the potential for automaticity?

Yes

What is the intrinsic rate of the SA node?

60-100bpm

What is the intrinsic rate of the AV node?

40-60 bpm`

What is the intrinsic rate of the purkinje network and ventricular cells?

20-40 bpm

Cardiac action potential