MEDICINE
CARDIOLOGY
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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has a shorter-than-normal refractory period, increasing the likelihood of severe bradycardia.
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is experiencing an extended refractory period, making the ventricles more vulnerable to dysrhythmias.
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is depolarizing too quickly, which significantly increases the potential for reentry in the AV junction.
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has a shortened refractory period and may be caused by factors such as hypocalcemia or pericarditis.
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Detailed explanation-1: -Prolonged QT interval. A prolonged QT interval is an irregular heart rhythm that can be seen on an electrocardiogram. It reflects a disturbance in how the heart’s bottom chambers (ventricles) send signals. In a prolonged QT interval, it takes longer than usual for the heart to recharge between beats.
Detailed explanation-2: -In people who have LQTS, the ion channels may not work well, or there may be too few of them. This may disrupt electrical activity in the heart’s lower chambers, or ventricles, and cause dangerous arrhythmias.
Detailed explanation-3: -The danger inherent in a prolonged QT is that excessive QT prolongation carries a risk of sudden cardiac death (SCD) due to polymorphic tachycardia, also known as TdP. Prolongation of ventricular repolarization often leads to oscillation in the membrane potential called early after depolarization (EAD).
Detailed explanation-4: -In experimental models, prolongation of the QT interval is associated with the occurrence of early after-depolarizations. Early after-depolarizations of sufficient amplitude can generate premature action potentials that lead to cardiac arrhythmias that may progress to ventricular fibrillation and sudden cardiac death.