Which condition is associated with no pulse and potential death if immediate pacemaker support is not provided?

Third-degree AV block, also known as complete heart block, is characterized by a complete dissociation between the atrial and ventricular electrical activities. In this condition, the atria and ventricles beat independently of each other, often leading to a significant drop in heart rate and cardiac output. The ventricles may rely on an escape rhythm, which is usually much slower than the normal heart rate.

This lack of coordinated electrical activity can result in a severely reduced heart rate, potentially leading to inadequate blood flow and, consequently, the absence of a palpable pulse. If immediate intervention, such as pacemaker support, is not provided, patients are at high risk of severe complications, including syncope, hemodynamic instability, or even death, due to ineffective heart function.

In contrast, conditions like first-degree and second-degree AV block do not typically result in complete dissociation between atrial and ventricular rhythms and usually do not lead to loss of pulse or immediate life-threatening situations. Sinus bradycardia may present with a slow heart rate, but there is usually still some degree of coordinated activity, and patients often have a pulse. Thus, in cases where there is an absence of a pulse and the risk of death without immediate intervention is present,