How to interpret EKGs better than you document a rash: Syncope Part 1
Residents are well programed to recognize cardiovascular emergencies such as STEMIs at a glance. However, during a busy shift it can be easy to overlook dysrhythmias and other electrophysiologic urgencies and emergencies. Syncope is a prime example of a chief complaint that may be uncovered with an EKG alone -- however syncopal emergencies are often subtle and nuanced. Dr. Berberian joins EMRA*Cast with Alex Kaminsky to delve deeper into the pathophysiology and electrical findings associated with diagnoses such as WPW, Brugada and ARVD in part 1 of this series.
- Prevalence: 0.7 to 1.7 per 10,000
Accessory Pathway Connecting the atria to the ventricle. In some instances, this can cause the accessory pathway to travel FASTER than through the AV node.
- Orthodromic (Narrow): Travels down the AV node (can bypass)
- Antidromic (Wide): Bypasses AV node and UP the his-purkinje system.
Courtesy of CardioNetworks: Free use image
Image Courtesy of EMRA EKG Guide
Most common presentation is SVT. But also can present as atrial fibrillation.
Orthodromic (Narrow): Treat like SVT
Key Point: Procainamide is the most safe chemical cardioversion in WPW as it does not directly affect the AV node. Use of AV-nodal blockers in WPW (including Amiodarone) increases the risk of VT/VF.
***Blocking the AV node in a WPW patient in Atrial Fibrillation can precipitate bad ventricular rhythms. If you see A-fib GREATER than 220 minus age -- consider WPW.***
Antidromic (Wide): Treat Like V-Tach
- Prevalence: 5 in 10,000. Traditionally taught more common in Southeast Asian populations.
- Sodium Channelopathy which can lead to unstable dysrhythmias and ultimately cardiac death.
- Diagnosis is made both by EKG and clinical criteria
- “Coved” ST-Elevation >2mm with a negatively deflected T in right precordial leads (V1-V3)
- Potentially diagnostic as isolated EKG finding.
- ST elevation in right precordial leads (V1-V3) with a “saddleback.” Within the STE.
- Not completely diagnostic but concerning fr workup.
Clinical Criteria (EKG Findings PLUS one or more):
- Nocturnal Agonal Respirations
- Brugada gets WORSE with parasympathetic stimuli.
- Family member with known Type 1
- Observed/Documented VT/VF
- Sudden cardiac death in family member <45 (Take that history!)
Arrhythmogenic Right Ventricular Dysplasia/Cardiomyopathy (ARVD)
- Prevalence: Unknown, likely more than we thought. Mean age is 31. Also we don’t have great clinical criteria to full encompass this -- yet. Multiple genes linked to disease process. Variable inheritance patterns.
- Fibro-Fatty infiltration of the myocardium that replaces good “conductive” tissue with fibrinous infiltrates. Think: “Kinda like cirrhosis of the heart.”
- Causes paroxysmal ventricular rhythms. Can present as CHF.
Image Courtesy of EMRA EKG Guide
- Epsilon wave -- AKA “The Ditzle or Nubbin” (only in 30% of patients)
- T-wave inversions in right precordial leads (V1-V3) -- (85% of patients)
- Long S-wave repolarization delay >55ms (in 95% of patients)
- Slightly prolonged QRS >110ms (Right precordial leads)
- VT looks more like a Left-bundle morphology -- Appreciate that AFTER the patient is out of VT.
References / Resources
- EMRA EKG Guide
- Clinical Policy: Critical Issues in the Evaluation and Management of Adult Patients Presenting to the Emergency Department with Syncope: Huff J.S., Decker W.W., Quinn J.V., Perron A.D., Napoli A.M., Peeters S., Jagoda A.S.( 2007) Annals of Emergency Medicine, 49 (4) , pp. 431-444.
- Epidemiological profile of Wolff-Parkinson-White syndrome in a general population younger than 50 years of age in an era of radiofrequency catheter ablation. Lu C.-W., Wu M.-H., Chen H.-C., Kao F.-Y., Huang S.-K. (2014) International Journal of Cardiology, 174 (3) , pp. 530-534.
- Reference, G. (2019). Brugada syndrome. [online] Genetics Home Reference. Available at: https://ghr.nlm.nih.gov/condition/brugada-syndrome#statistics [Accessed 14 Feb. 2019].
- McNally E, MacLeod H, Dellefave-Castillo L. Arrhythmogenic Right Ventricular Cardiomyopathy. 2005 Apr 18 [Updated 2017 May 25]. In: Adam MP, Ardinger HH, Pagon RA, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2019. Available from: https://www.ncbi.nlm.nih.gov/books/NBK1131/