A 21 y/o M presents with chest pain and sudden syncope while walking to class earlier this morning. He had no other preceding symptoms. There was no seizure activity reported by witnesses. He denies any past medical or surgical history. He reports he thinks his father has an abnormal heart rhythm, but isn’t aware of any other details.
Name 4 classic abnormalities to consider on EKG review of a young stable adult with syncope.
Then, match the arrhythmia with an associated term.
(A) Brugada Syndrome (1) Human Ether-a-go-go
(B) Wolf Parkinson White Syndrome (2) Saddleback
(C) Hypertrophic Cardiomyopathy (3) Crescendo-Decrescendo
(D) Prolonged QT (4) Bundle of Kent
Abnormality of cardiac voltage-gated sodium channels. Characteristic ECG findings are ST elevations that are seen in precordial leads and an incomplete RBBB. The three Brugada types are shown in the image below:
Type 1 ECG pattern shows pronounced elevation of the J point (arrow), a coved-type ST segment, and an inverted T wave in V1 and V2. Type 2 is shown with a saddleback ST-segment elevated by >1 mm. The pattern shown in the right panel is type 3 in which the ST segment is elevated < 1 mm.
Abnormal accessory electrical pathway between atria and ventricles, bypassing the AV node and allowing for both normal sinus impulses to travel normally via AV node, and more rapidly conducted signaling via the Bundle of Kent. This leads to ventricular pre-excitation and reentrant tachycardia, which may evolve to cardiogenic shock and ventricular fibrillation. On EKG, your classic findings will include a Delta wave, shortened PR Interval, and widened QRS, and secondary repolarization changes.
HCM is an autosomal dominant inherited disease characterized by LVH and can lead to LV outflow obstruction, diastolic dysfunction, MI, mitral regurgitation. Sudden death is thought to be due to tachyarrhythmia’s caused by myocyte disarray and myocardial fibrosis. The murmur of HCM is a systolic crescendo-decrescendo murmur, best heard at apex and lower left sternal border, and can be made louder by maneuvers that reduced preload such as Valsalva. It is made softer by squatting or leg elevation (raise preload) and by handgrip (raise afterload). ECG findings shown below include prominent voltages with repolarization changes, prominent abnormal Q wave in inferior and lateral leads, abnormal P waves (atrial enlargement).
A long QT can be congenital or acquired due to medication / metabolic abnormalities or bradyarrhythmias. Prolonged QT can lead to polymorphic ventricular tachycardia, known as Torsades de Pointes. It is precipitated by a sequence of long-short RR intervals. The pathophysiology of the prolonged QT syndrome is it generally thought to be related to ion channel abnormalities and specific genetic mutations. The human Ether-a-go-go gene is responsible for LQT2, as it codes for a subunit of a K ion channel. All forms of LQT relate to abnormal repolarization. Although there is no standard cutoff, generally QTc > 450 in a male, > 480 in a female is considered prolonged.
A: Prolonged QT, B: Evolution into Torsades de pointes
Thank you to Dr. Gutierrez and Dr. Hernandez for inspiring this pearl.