What happens when a patient has a left bundle branch block?

When a patient has a left bundle branch block, the electric signals are indeed impeded from traveling through the left ventricle. This occurs because the left bundle branch, which conducts impulses to the left side of the heart, is blocked. As a result of this blockage, the electrical activation of the heart is delayed in the left ventricle compared to the right ventricle.

This delay is reflected on an electrocardiogram (ECG) by a widening of the QRS complex, indicating an alteration in the usual conduction pattern through the ventricles. This can lead to a decreased efficiency of the heart’s pumping ability, as the coordinated contraction between the right and left ventricles is disrupted. Overall, this condition can lead to various symptoms, including heart palpitations or signs of heart failure, depending on the underlying heart health of the patient and the presence of any other cardiac conditions.

The other choices provided do not accurately describe the characteristic effects of a left bundle branch block on the cardiac conduction system or the electrocardiogram's appearance.