What effect may digitalis have on the QT interval?

What effect may digitalis have on the QT interval?

• A. Lengthened
• B. Shortened
• C. No change
• D. Inverted

Answer: (B)

Digitalis, a medication derived from the foxglove plant, is primarily used in the management of certain heart conditions, most notably atrial fibrillation and heart failure. One of its effects on the cardiovascular system is the influence it exerts on the QT interval. The QT interval on an electrocardiogram (ECG) represents the time it takes for the heart's ventricles to depolarize and then repolarize (essentially, it reflects the duration of the heart's electrical cycle). Digitalis can lead to shortening of the action potential duration, which directly affects the QT interval. This shortening occurs due to digitalis's effect on the cardiac action potential and its influence on calcium influx into the myocardial cells. When the action potential duration decreases, the QT interval also decreases. Therefore, as a result of these pharmacological interactions, digitalis is known to lead to a shortened QT interval on an ECG. Understanding this effect is crucial in clinical scenarios as changes to the QT interval can have significant implications for arrhythmia risk and overall patient management in cardiac conditions.

Digitalis, a medication derived from the foxglove plant, is primarily used in the management of certain heart conditions, most notably atrial fibrillation and heart failure. One of its effects on the cardiovascular system is the influence it exerts on the QT interval.

The QT interval on an electrocardiogram (ECG) represents the time it takes for the heart's ventricles to depolarize and then repolarize (essentially, it reflects the duration of the heart's electrical cycle). Digitalis can lead to shortening of the action potential duration, which directly affects the QT interval.

This shortening occurs due to digitalis's effect on the cardiac action potential and its influence on calcium influx into the myocardial cells. When the action potential duration decreases, the QT interval also decreases. Therefore, as a result of these pharmacological interactions, digitalis is known to lead to a shortened QT interval on an ECG.

Understanding this effect is crucial in clinical scenarios as changes to the QT interval can have significant implications for arrhythmia risk and overall patient management in cardiac conditions.