Third degree heart block occurs when the electrical signal from the heart’s atria, or top chambers, cannot reach the ventricles, or bottom chambers. Without treatment, the heart may eventually stop.

Sinus rhythm; 3rd degree AV block; Ventricular pacing; This ECG shows ventricular pacing. Note the pacer spike prior to each QRS complex, most apparent in leads V5 and V6.

Third-degree heart block is the most serious of the three types of heart block. It's often triggered by a heart attack but can also have other causes.

Trained athletes commonly (up to 80%) show ECG changes such as sinus bradycardia, first-degree atrioventricular (AV) block and early repolarisation, which result from physiological adaptation of the ...

This is not recognizable on the 12-lead ECG because the time that SA node fires is not able to be ... Third-degree sinoatrial exit block occurs when no SA nodal action potentials are able to leave ...

Third-degree heart block prevents the electrical signal from the atria from reaching the ventricles. This leads to a very low escape rhythm from the ventricles, which can lead to severe complications.

If not treated effectively, second-degree heart block can lead to ongoing symptoms, such as fainting and low blood pressure, or to more serious complications if the condition worsens into third ...