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67. Wolff-Parkinson-White: Who’s Afraid of the Big Bad Wolff?
Keywords
Wolff-parkinson-whiteVentricular pre-excitationAccessory pathwayCase 1
Pertinent History
A 32-year-old male presented to the emergency department complaining of a “racing heart beat.” He explained that earlier in the morning, while eating breakfast, he felt his heart pounding and beating very fast. He expressed that he felt somewhat light-headed when walking. He denied any associated symptoms such as fever, chest pain or pressure, cough, or recent alcohol use. He drank a cup of coffee this morning which is a normal for him to do.
No Relevant Past Medical or Surgical History
Social History
Married with one child. He is a nonsmoker and denies illicit drug use. He admitted to occasional alcohol use.
Family History
There was no family history of sudden cardiac death.
Pertinent Physical Examination
Except as noted below, the findings of a complete physical exam are within normal limits.
Vitals: 98.7F/37C; HR, 203; BP, 115/62; RR, 18.
General: Alert, thin, and pale male sitting on the cot in minimal distress.
Cardiovascular: Tachycardic, regular rhythm, 2+ peripheral pulses, warm and well perfused.
Pertinent Test Results
Laboratory studies were unremarkable.
ED Management
The patient was connected to a continuous 12-lead ECG machine. Carotid massage and Valsalva maneuvers were attempted without termination of his rhythm; 12 mg of adenosine was administered via rapid push method and the rhythm subsequently terminated. The following ECG was obtained prior to adenosine.
Patient’s EKG Before Adenosine
EKG courtesy of Colin Kaide, MD
Patient’s EKG After Adenosine
EKG courtesy of Colin Kaide, MD
Case 2
Pertinent History
A 40-year-old female was brought to the emergency department by EMS after she had an episode of syncope while at work. She expressed that she had been feeling unwell throughout the day and felt especially out of breath. She had associated nausea without vomiting or fevers. She worked at a warehouse and had been carrying some boxes when she suddenly became lightheaded and collapsed to the floor. Per bystanders, she was unconscious for only a few seconds. Upon awakening, she was immediately alert and oriented. Coworkers did not witness tonic-clonic activity. Upon EMS arrival, the patient’s blood glucose was 124. EMS reported that the ECG obtained showed an irregularly irregular wide-complex rhythm.
No Relevant Past Medical or Surgical History
Social History
Employed at a warehouse. She smokes marijuana and cigarettes daily, while using alcohol socially. She denied other drug use.
Relevant Family History
The patient’s father had an unknown heart condition and suffered from a sudden cardiac death.
Pertinent Physical Examination
Except as noted below, the findings of a complete physical exam are within normal limits.
Vitals: 99.1, BP 102/50; HR, 210; RR, 18; O2, 97%.
General: An alert, age-appropriate female sitting up in the cot, who appears somewhat diaphoretic.
HEENT: Dry mucous membranes.
Cardiovascular: Tachycardic, irregularly irregular rhythm, thready pulses.
Extremities: Clammy extremities and skin.
Pertinent Labs
Laboratory studies, including thyroid studies and HCG, were unremarkable.
Patient’s EKG
EKG courtesy of Andrew King, MD
ED Management
The patient was placed on a cardiac monitor and intravenous access was obtained. The ECG was read as atrial fibrillation with rapid ventricular response (RVR) and was given diltiazem 15 mg intravenously in attempt to improve the ventricular rate; however, over the next few minutes, the patient appeared more diaphoretic, pale, and drowsy. Repeat vitals showed a BP 70/42 with a HR 261. Given her decompensation, synchronized cardioversion was performed which terminated the rhythm. A repeat ECG showed findings that were concerning for underlying WPW.
Learning Points
Priming Questions
- 1.
What is the pathophysiology for WPW and what are the characteristic EKG findings?
- 2.
What is the best approach to management of a symptomatic WPW patient?
- 3.
What agents should be avoided in WPW patients presenting with irregular wide complex tachycardia?
Introduction/Background
- 1.
The Wolff-Parkinson-White (WPW) pattern was first described by Drs. Wolff, Parkinson, and White in 1930 from 11 case reports of patients identified to have short PR intervals and bundle branch block who resultantly developed supraventricular tachycardia and atrial fibrillation [1, 2].
- 2.
WPW is a form of ventricular pre-excitation in which an accessory pathway exists between the atria and the ventricles. These pathways allow for conduction of impulses between the atria and ventricle to occur in addition to the normal conduction through the atrioventricular (AV) node and the His-Purkinje pathway.
- 3.
The pattern occurs in about 0.13–0.25% of the general population, whereas the syndrome, the development of a tachyarrhythmia leading to symptoms, occurs in 0.07–1.8% of those with the pattern. Most people with WPW are asymptomatic with no associated arrhythmias [3, 4]. Sudden cardiac death is rare, with a rate of 0.00125–0.0015 per patient-year [5] with rates being slightly higher in children [6].
Physiology/Pathophysiology
- 1.
Normal conduction between the atria and ventricles occurs through the AV node and then proceeds rapidly down the His-Purkinje system to cause ventricular contraction. When accessory pathways exist, some of these signals will transmit down these pathways to reach the ventricle.
A shortened PR interval is created because unlike the AV node which slows electrical signals, the accessory pathway allows for signals to pass quickly.
Once these accessory signals reach the ventricles, they travel much slower than those signals which propagate through the His-Purkinje system. In WPW, there are signals going down both the AV node/His-Purkinje system and the accessory pathway. This leads to the characteristic delta wave, or slurred upstroke of the QRS, on ECG [7].
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