Brugada syndrome electrocardiogram
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
There are three electrocardiographic patterns associated with Brugada syndrome: Type I, Type II and Type III. The diagnosis of Brugada syndrome is based upon the presence of Type I EKG changes. Patients with Type II or Type III Brugada patterns can convert to a Type I Brugada pattern following the administration of sodium channel blockers such as ajmaline and flecainide. Type 1 Brugada syndrome may always be present on the EKG, or it may be elicited by the administration of particular drugs (e.g., Class IC antiarrythmic drugs that blocks sodium channels such as ajmaline, flecainide) or it may be unmasked by various triggers or risk factors.
Type 1 Brugada pattern is characterized by ST elevations in leadsV1-V3 with a right bundle branch block (RBBB). A prolongation of the PR interval is also frequently seen. The EKG changes of Brugada syndrome can vary over time, depending on the autonomic balance and the administration of antiarrhythmic drugs. Adrenergic stimulation decreases the ST segment elevation, while vagal stimulation worsens it. The administration of class Ia, Ic and III drugs increases the ST segment elevation, as does fever. Exercise decreases ST segment elevation in some patients but increases it in others (after exercise when the body temperature has risen). The changes in heart rate induced by atrial pacing are accompanied by changes in the degree of ST segment elevation. When the heart rate decreases, the ST segment elevation increases and when the heart rate increases the ST segment elevation decreases.
The three patterns of Brugada syndrome (Type I,II,III) are shown below:
Diagnostic Criteria for Brugada Syndrome[1]
1. The presence of Type 1 ST-segment elevation in more than one right precordial lead (V1-V3). Type I ST elevation must be observed either spontaneously or following the administration of a sodium channel blocking agent.
2. One or more of the following criteria must also be met:
- Family history of sudden cardiac death (SCD) (<45 years old)
- Documented ventricular fibrillation (VF)
- Polymorphic ventricular tachycardia
- Coved-type ECG changes in family members
- Inducibility of ventricular tachycardia (VT) with programmed electrical stimulation (PES)
3. The patient is also diagnosed as having Brugada syndrome when a Type 2 (saddleback pattern) or Type 3 ST-segment elevation is observed in more than one right precordial lead under baseline conditions and that can be converted to the diagnostic Type 1 pattern following administration of a sodium channel blocker.
Type 1 Brugada Syndrome
As shown by the tracing below, the EKG characteristics of Type 1 Brugada syndrome include the following EKG findings in the right precordial leads (V1-V3):
- a) A broad P-wave with some PQ prolongation
- b) J point elevation in the right precordial leads (V1-V3)
- c) Coved ST segment elevation
- d) An inverted T wave
Typically these changes are in the right precordial leads but these EKG changes can occur in the inferior [2] or left precordial leads[3]. The fact that these cases may represent atypical variants of Brugada syndrome is supported by the observation that these cases were associated with SCN5A genetic abnormalities.
Shown below is an example of the EKG characteristics in Type I Brugada syndrome - a right bundle branch block morphology in leads V1-3 and ST segment elevation in leads V1-3:
Unmaksing Type 1 Brugada Syndrome
The electrocardiographic findings of Type 1 Brugada syndrome are often concealed, but may be unmasked by placing the leads higher on the chest (i.e. using the "Brugada Leads") or by infusion of a sodium channel blockers. Infusion of a sodium channel blocker may also convert a Type II or Type III Brugada pattern to a Type I Brugada pattern to establish a definitive diagnosis of the syndrome.
Unmasking Brugada Syndrome by Positioning the EKG Leads Higher on the Chest Wall: The Brugada Leads
The The electrocardiographic findings of Brugada syndrome can be unmasked by placing the electrocardiographic leads higher on the chest. The EKG leads should be placed on the second and third intercostal space rather than the fourth intercostal space as shown below. When the electrodes are placed in this higher position they are called Brugada leads.
Sodium Channel Blocker Challenge
Agents
Several sodium channel blockers are effective in unmasking Type 1 Brugada syndrome and in converting Type II and III Brugada syndrome to Type I to establish the diagnosis of Brugada syndrome. These agents include:
- Ajmaline 1 mg/kg/5 min IV
- Flecainide 2 mg/kg/10 min IV or 400 mg PO
- Procainamide 10 mg/kg/10 min IV
- Pilsicainide 1 mg/kg/10 min IV
When to Terminate the Sodium Channel Blocker Infusion
The sodium challenge should be terminated when:
- A diagnostic Type 1 Brugada pattern ST-segment elevation develops
- The ST segment elevation in Type 2 increases by ≥ 2 mm
- Premature ventricular beats or other arrhythmias develop
- the QRS widens to ≥ 130% of baseline
Type II Brugada Syndrome
The Type II Brugada pattern is not diagnostic of Brugada syndrome. The Type II Brugada pattern is characterized by a "saddleback appearance" to the ST segment. The ST segment must be elevated greater than 2 mm, and the trough of the ST segment elevation at the bottom of the saddle must be elevated > 1 mm. The Type II Brugada pattern may alternate with the Type I Brugada pattern at different times in the same patient.
In order for a patient with type II Brugada pattern to be diagnosed as having Brugada syndrome, there must be a conversion of the Type II pattern to a Type I pattern with greater than 2 mm of ST segment elevation in the right precordial leads (either spontaneously or following infusion of a sodium channel blocking agent). In addition to these electrocardiographic changes, the required clinical criteria to establish the diagnosis of Brugada syndrome described above for the Type I brugada pattern must also be present.
Shown below are examples of the Type II Brugada pattern demonstrating J point elevation, and a "saddle shaped" ST segment:
Type III Brugada Syndrome
The Type 3 Brugada pattern is associated with either a "saddleback" or a "coved" appearance but the magnitude of ST-segment elevation is <1 mm. Normal 0 false false false EN-US X-NONE X-NONE
A sodium channel blocker infusion can be administered to convert a type III Brugada pattern to a type I Brugada pattern to facilitate the definitive diagnosis of Brugada syndrome, however the conversion of a type III Brugada pattern to a type II Brugada pattern is not considered diagnostic of the Brugada syndrome.[1]
References
- ↑ 1.0 1.1 Antzelevitch C, Brugada P, Borggrefe M, Brugada J, Brugada R, Corrado D, Gussak I, LeMarec H, Nademanee K, Perez Riera AR, Shimizu W, Schulze-Bahr E, Tan H, Wilde A (2005). "Brugada syndrome: report of the second consensus conference". Heart Rhythm : the Official Journal of the Heart Rhythm Society. 2 (4): 429–40. PMID 15898165. Unknown parameter
|month=ignored (help);|access-date=requires|url=(help) - ↑ Kalla H, Yan GX, Marinchak R (2000). "Ventricular fibrillation in a patient with prominent J (Osborn) waves and ST segment elevation in the inferior electrocardiographic leads: a Brugada syndrome variant?". Journal of Cardiovascular Electrophysiology. 11 (1): 95–8. PMID 10695469. Unknown parameter
|month=ignored (help);|access-date=requires|url=(help) - ↑ Horigome H, Shigeta O, Kuga K, Isobe T, Sakakibara Y, Yamaguchi I, Matsui A (2003). "Ventricular fibrillation during anesthesia in association with J waves in the left precordial leads in a child with coarctation of the aorta". Journal of Electrocardiology. 36 (4): 339–43. PMID 14661171. Retrieved 2012-10-14. Unknown parameter
|month=ignored (help)