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.

Electrocardiogram

Type 1 Brugada pattern is characterized by ST elevations in leads V1-V3 with a right bundle branch block (RBBB) like pattern, although it is actually a cause of "pseudo right bundle branch block" as electrocardiographically right bundle branch block is not actually present. 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:

The table below is from ECGpedia and is adapted from Wilde et al.[1]

ST segment abnormalities in the different types of Brugada syndrome
Type I Type II Type III
J wave amplitude >= 2mm >= 2mm >= 2mm
T wave Negative Positive or biphasis Positive
ST-T configuration Coved type Saddleback Saddleback
ST segment (terminal portion) Gradually descending Elevated >= 1mm Elevated < 1mm

Brugada syndrome algorithm is shown below.

Type 1 Brugada Pattern

As shown by the tracing below, the EKG characteristics of Type 1 Brugada pattern include the following EKG findings in the right precordial leads (V1-V3):

Slight QT prolongation may also be observed, particularly in the right precordial leads.[2][3][4] Typically these changes are in the right precordial leads but these EKG changes can occur in the inferior [5] or left precordial leads[6]. 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 EKG characteristic in Type I Brugada syndrome - a right bundle branch block morphology in leads V1-3 and ST segment elevation in leads V1-3:

For more examples of Type I Brugada syndrome, click here

Unmaksing Type 1 Brugada Pattern

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 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.[7][8]

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:

When to Terminate the Sodium Channel Blocker Infusion

The sodium challenge should be terminated when:

  1. A diagnostic Type 1 Brugada pattern ST-segment elevation develops
  2. The ST segment elevation in Type 2 increases by ≥ 2 mm
  3. Premature ventricular beats or other arrhythmias develop
  4. The QRS widens to ≥ 130% of baseline

Precautions

The infusion should be carried out in a highly monitored area equipped to perform resuscitation. In an elderly patient with prolongation of the electrocardiographic intervals, the test is best performed in the electrophysiology laboratory. Exercise caution in the presence of pre-existing conduction abnormalities, or in the presence of QRS prolongation as the infusion may cause complete AV block. Isoproteronol can be used as an antidote should this complication should occur.

Type II Brugada Pattern

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 EKGs of the Type II Brugada pattern demonstrating J point elevation, and a "saddle shaped" ST segment:

Type III Brugada Pattern

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.

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.

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.[9]

Sources

Copyleft images obtained courtesy of ECGpedia, http://en.ecgpedia.org/index.php?title=Special:NewFiles&offset=&limit=500

References

  1. Wilde AA, Antzelevitch C, Borggrefe M, Brugada J, Brugada R, Brugada P, Corrado D, Hauer RN, Kass RS, Nademanee K, Priori SG, Towbin JA (2002). "Proposed diagnostic criteria for the Brugada syndrome: consensus report". Circulation. 106 (19): 2514–9. PMID 12417552. Retrieved 2012-10-14. Unknown parameter |month= ignored (help)
  2. Alings M, Wilde A. “Brugada” syndrome: clinical data and suggested pathophysiological mechanism. Circulation. 1999; 99: 666–673.
  3. Bezzina C, Veldkamp MW, van Den Berg MP, Postma AV, Rook MB, Viersma JW, Van Langen IM, Tan-Sindhunata G, Bink-Boelkens MT, van Der Hout AH, Mannens MM, Wilde AA. A single Na(+) channel mutation causing both long-QT and Brugada syndromes. Circ Res. 1999; 85: 1206–1213.
  4. Priori SG, Napolitano C, Gasparini M, Pappone C, Della Bella P, Brignole M, Giordano U, Giovannini T, Menozzi C, Bloise R, Crotti L, Terreni L, Schwartz PJ. Clinical and genetic heterogeneity of right bundle branch block and ST-segment elevation syndrome: a prospective evaluation of 52 families. Circulation. 2000; 102: 2509–2515.
  5. 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)
  6. 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)
  7. Shimizu W, Matsuo K, Takagi M, Tanabe Y, Aiba T, Taguchi A, Suyama K, Kurita T, Aihara N, Kamakura S (2000). "Body surface distribution and response to drugs of ST segment elevation in Brugada syndrome: clinical implication of eighty-seven-lead body surface potential mapping and its application to twelve-lead electrocardiograms". Journal of Cardiovascular Electrophysiology. 11 (4): 396–404. PMID 10809492. Unknown parameter |month= ignored (help); |access-date= requires |url= (help)
  8. sukhowong P, Tungsanga K. New electrocardiographic leads and the procainamide test for the detection of the Brugada sign in sudden unexplained death syndrome survivors and their relatives. Eur Heart J. 2001; 22: 2290–2296.
  9. 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)

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