A 24-year-old man comes to the physician with a 6-month history of intermittent palpitations. He reports a sudden onset of fluttering in his chest that lasts 30-40 minutes and stops spontaneously or after deep breathing maneuvers. The episodes occur about once a month and are not related to physical activity. He has no chest pain, dizziness, dyspnea, or syncope.
Jugular venous pressure is estimated at 4 cm H₂O. There are no cardiac murmurs or additional heart sounds. Peripheral pulses are 2+ and symmetrical bilaterally.
ECG is shown in this exhibit.
The PR interval duration is 100 msec and the QRS complex duration is 140 msec.
Which of the following findings would most likely be seen during episodes of palpitations in this patient?

Question

A 24-year-old man comes to the physician with a 6-month history of intermittent palpitations. He reports a sudden onset of fluttering in his chest that lasts 30-40 minutes and stops spontaneously or after deep breathing maneuvers. The episodes occur about once a month and are not related to physical activity. He has no chest pain, dizziness, dyspnea, or syncope.
Jugular venous pressure is estimated at 4 cm H₂O. There are no cardiac murmurs or additional heart sounds. Peripheral pulses are 2+ and symmetrical bilaterally.
ECG is shown in this exhibit.

The PR interval duration is 100 msec and the QRS complex duration is 140 msec.
Which of the following findings would most likely be seen during episodes of palpitations in this patient?

Quizplus · Accepted Answer

This patient's presentation and ECG findings are consistent with Wolff-Parkinson-White (WPW) syndrome. When there is no reentrant tachycardia in WPW patients, normal sinus impulses reach the ventricles first via the accessory pathway and shortly thereafter via the atrioventricular (AV) node. This leads to preexcitation and the classic findings of short PR interval, delta wave, and widened QRS on ECG. However, the majority of patients with WPW pattern on baseline ECG are asymptomatic. ECG findings accessory pathway WPW syndrome refers to patients with pre-existing WPW pattern on ECG who develop symptomatic supraventricular arrhythmias involving the accessory pathway. These symptoms include palpitations, lightheadedness, presyncope or syncope, chest pain, and sudden cardiac death (in about 1% of patients). Symptomatic supraventricular arrhythmias occur as the accessory pathway no longer pre-excites the ventricles but instead forms a reentrant circuit back to the atria. This causes the initial widened QRS complex to convert to a narrow QRS tachyarrhythmia. Atrioventricular reentrant (or reciprocating) tachycardia (AVRT) is the most common supraventricular arrhythmia and is found in up to 80% of WPW syndrome patients. AVRT usually manifests as a regular narrow QRS complex tachycardia on ECG. reentrant circuit (Choices A and B) Atrial fibrillation can occur in 15%-30% of patients with WPW syndrome. Accessory pathways with short refractory periods can preferentially transmit atrial impulses via the accessory pathway to the ventricle to cause an irregular (supraventricular tachycardia with aberrancy) or regular (ventricular tachycardia) wide QRS complex tachycardia. Rapid repetitive ventricular conduction can lead to rapid ventricular response and subsequent ventricular fibrillation. (Choice C) Junctional escape beats occur when the sinus rate falls below the discharge rate of the sinoatrial node. The AV node becomes the dominant pacemaker. However, junctional escape beats are not as commonly associated with WPW as narrow QRS complex tachycardias. (Choice E) Antidromic AVRT is the least common arrhythmia associated with WPW syndrome. Antegrade conduction occurs via the accessory pathway, and retrograde conduction occurs through the AV node/His-Purkinje system. This causes a regular wide QRS complex tachycardia. Educational objective: ECG findings in Wolff-Parkinson-White (WPW) pattern include short PR interval, delta wave, and widened QRS complexes. Asymptomatic patients have WPW pattern, and symptomatic patients have WPW syndrome. The most commonly associated supraventricular arrhythmia is atrioventricular reentrant (or reciprocating) tachycardia, a regular and narrow complex reentrant tachycardia. __________ References: WPW and preexcitation syndromes. (http://www.ncbi.nlm.nih.gov/pubmed/18368860)

A 24-Year-Old Man Comes to the Physician with a 6-Month