Figure 7.1.1
Note the presence of r′ in V1–V2 with a small ST ascent in V1–V2 and a negative T wave in V1. What is the explanation?
Questions
A. There are many causes that may explain r′ in V1–V2:
1. High location of electrodes in V1 and V2
2. Pectus excavatum
3. Wolff–Parkinson–White (WPW)
4. Athlete’s ECG
5. Right ventricular hypertrophy
6. Partial right bundle branch block
7. Brugada pattern type 2: Saddle-back type
8. Arrhythmogenic right ventricular dysplasia (ARVD)
9. Hyperkalemia
10. Lateral MI
B. Which of these causes best explains the r′ in V1 shown in the ECG of Figure 7.1.1?
Interpretation, Answer and Comments
The correct answer is 7, Brugada pattern.
A. The electrodes are located in the correct place: the fourth intercostal space (ICS). It was not necessary to record the ECG in the second ICS. However, it is always recommended to do so, as seen in Figure 7.1.2.
Figure 7.1.2 Electrocardiogram of a young male with non-vasovagal syncope. A. The ECG in the fourth ICS is suspicious of Brugada pattern type 2 (V2). B. With the electrodes located in the second ICS, the ECG is typical of Brugada pattern type 2. The diagnosis was confirmed by the ajmaline test, whereby the typical ECG pattern type 1 was observed.
B. Recently, the characteristics of r′, especially the slope of the descending arm, have been shown to be useful in the differential diagnosis, especially between Brugada pattern type 2, athlete’s heart, right ventricular hypertrophy, and incomplete bundle branch block.
a. Chevallier et al. reported that a wider angle between the two arms in V1–V2 (>58°) as a diagnostic criteria for Brugada pattern type.
b. According to Serra et al., a triangle base > 180 ms (4 mm) is very suggestive of Brugada pattern type 2 (Se 85, Sp 96, PPV 95, NPP 88). In doubtful cases, the ajmaline test may confirm the diagnosis.
In this case (Figure 7.1.3), the base measures 188 ms, indicating Brugada pattern, a diagnosis that was supported by clinical family history and a positive ajmaline test. Athletes, right ventricular hypertrophy (RVH), and partial right bundle branch block present a quicker descending slope of r′ (see Figure 7.1.4).
Figure 7.1.3 In the r′ of V2 the base of the triangle may be measured to demonstrate if it is > or < 160 ms (4 mm).
Figure 7.1.4 A. A typical case of an athlete with r′ in V1 and V2. The slope of the descending arm is very quick (triangle base 40 ms). B. An example of V2 in a case of Brugada pattern type 2. Note the clear upstroke of ST and the much longer triangle base (184 ms) when compared to the athlete (40 ms) due to the slower descending arm of the triangle.
C.Usually, only Brugada pattern type 2 and sometimes pectus excavatum, present ST elevation in V1–V2. In Table 7.1.1, we see the ECG criteria for Brugada pattern type 2 according to the new consensus paper published in 2012.1
Table 7.1.1
Type 2: Brugada pattern. ECG characteristics (modified from Bayés de Luna et al.)1
For this typical saddle-back pattern present in V1-V2, the following characteristics are present:
a. High take-off in r′ (which often does not coincide with J point) ≥ 2 mm
b. Descending arm of r′ coincides with beginning of ST (is often not well seen).
c. Minimum ST ascent ≥ 0.5 mm.
d. ST is usually followed by a positive T wave in V2 (T peak > ST minimum > 0) and variable morphology in V1.
e. The characteristics of the triangle formed by r′ allow different criteria useful for diagnosis to be defined (see text and Figures 7.1.3–7.1.5).
• β angle2
• Duration of the base of the triangle of r′ at 5 mm from the high take-off greater than 4 mm3
f. The duration of QRS is usually longer in BrP type 2 than in other cases with r′ in V1. There is a mismatch between V1 and V6 that may also be seen in ARVD and hyperkalemia (see Figure 7.5.5).
g. It is necessary to record the ECG in the second ICS (see Figure 7.1.2), and to perform an ajmaline test if there is any doubt.
D.The patient does not present pectus excavatum. Furthermore, the P wave in V1 is not negative and the descending limb of r′ is very quick.
E. There is no delta wave and the PR interval is normal, thus excluding Wolff–Parkinson–White syndrome.
F. The differential diagnosis between Brugada pattern type 2 and athletes is also based on the characteristics of r′ (see Figures 7.1.4 and 7.1.5).
Figure 7.1.5 Proposed diagnostic algorithm for patients with r′ in leads V1–V2 with the most important differential diagnosis characteristics.
Baranchuk et al.4 published an algorithm that summarizes its criteria. It is recommended to follow this algorithm to help in carrying out the correct diagnosis.
G. Cases of RVH usually correspond to an atrial septal defect and in some cases of mild pulmonary hypertension. In these cases the base of triangle is narrow. In some occasions, auscultation of a murmur and an abnormal echocardiogram may help in differential diagnosis.
H. In arrhythmogenic right ventricular dysplasia (ARVD) and hyperkalemia, the base of triangle may be wider than 160 ms and may also be seen in both cases as a mismatch between V1 and V6 (Figure 7.1.5). However, in these cases the following characteristics may help the diagnosis (Figure 7.1.5).5
a. Hyperkalemia. Positive T wave in V1–V2 > 7 mm.
b. ARVD. No ST elevation in V1–V2. Negative and usually symmetric T wave in V1–V4.
I. Finally, in rare cases of lateral myocardial infarction MI in V1 a final r′ may be present but usually with the pattern Rr′ or rsr′. What is not seen is the rSr′ morphology.
Conclusion
The presence of r′ in V1–V2 is a frequent finding that obliges us to perform a careful differential diagnosis because there are many causes that may present this pattern, some of which are potentially dangerous. Although an experienced cardiologist may reach the diagnosis easily, it is recommended to follow Baranchuk’s algorithm,4,5 and consult Table 7.1.1.
References
1. Bayés de Luna A, Brugada J, Baranchuk A, et al. Current electrocardiographic criteria for diagnosis of Brugada pattern: A consensus report. J Electrocardiol. 2012;45:433–442.
2. Chevallier S, Forclaz A, Tenkorang J, et al. New electrocardiographic criteria for discriminating between Brugada types 2 and 3 patterns and incomplete right bundle branch block. J. Am. Coll. Cardiol. 2011;58:2290.
3. Serra G, Baranchuk A, Bayés de Luna A, et al. New electrocardiographic criteria to differentiate type-2 Brugada pattern from the electrocardiogram of healthy athletes with r′ wave in leads V1/V2. Europace. 2014;16:1639–1645.
4. Baranchuk A, Enriquez A, Garcia-Niebla J, et al. Differential diagnosis of rSr′ pattern in leads V1-V2 comprehensive review and proposed algorithm. Ann. Noninvasive Electrocardiol. 2015; 20 (1): 7–17.
5. Bayés de Luna A. Clinical Electrocardiography, Fourth Edition. Hoboken, NJ. Wiley-Blackwell. 2012:103.
Pedro Brugada, MD, PhD Sergio Richter, MD | CASE 7.2 |
Figure 7.2.1
Eighteen different genes are now known to be related to Brugada syndrome. The most commonly found abnormalities in families with Brugada syndrome are related to mutations in the cardiac sodium-channel gene SCN5A. However, mutations in genes encoding for potassium and calcium cardiac channels can also cause the Brugada phenotype.
Question
1. Given the electrocardiogram (ECG) abnormalities, what are the most likely affected genes in the patients in panels A and B?
1. Panel A calcium channel, panel B potassium channel.
2. Panel A sodium channel, panel B potassium channel.
3. Panel A sodium channel, panel B sodium channel.
Answer
The correct answer is 2.
References
1. Brugada P. Brugada syndrome: More than 20 years of scientific excitement. J. Cardiol. 2016 Mar.;67(3):215–20.
2. Brugada P, Brugada J. Right bundle branch block, persistent ST-segment elevation and sudden cardiac death: A distinct clinical and electrocardiographic syndrome. A multicenter report. J. Am. Coll. Cardiol. 1992;20:1391–1396.
3. Antzelevitch C. The Brugada syndrome: Diagnostic criteria and cellular mechanisms. Eur. Heart J. 2001;22:356–363.
4. Brugada J, Brugada R, Brugada P. Right bundle branch block, ST-segment elevation in lead V1 through V3 and sudden cardiac death: A marker for sudden death in patients without demonstrable structural heart disease. Circulation. 1998;97:457–460.
5. Brugada P, Brugada J, Roy D. Brugada syndrome 1992–2012: 20 years of scientific excitement, and more. Eur. Heart J. 2013;34:3610–3615.
Pedro Brugada, MD, PhD Sergio Richter, MD | CASE 7.3 |
Patient History
The ECG on February 5th (precordial leads only) was recorded immediately after cardiopulmonary resuscitation in a 40-year-old Japanese male. It shows the typical features of a type 1 ECG compatible with Brugada syndrome. Within the following days, the ST elevation disappears. The ECG is no longer a type 1, but a type 2 or type 3 Brugada ECG.
Figure 7.3.1
Question
Are there any features on the ECGs of February 7th–13th that would make you suspicious of Brugada syndrome even if you did not have the ECG of February 5th available?
Answer
The ECGs from February 7th–13th show an R′ that does not correspond to a simple incomplete right bundle branch block. The R′ is too broad. The angle between the ascending limb of the S wave and the descending limb of the R′ is too wide (see Figure 7.3.2). Although this feature is not diagnostic of Brugada syndrome, it should make you suspicious about the diagnosis.
Figure 7.3.2 ECGs from February 7th–13th. Precordial leads V1 and V2.
References
1. Brugada P. Brugada syndrome: More than 20 years of scientific excitement. J. Cardiol. 2016 Mar.;67(3):215–20.
2. Brugada P, Brugada J. Right bundle branch block, persistent ST-segment elevation and sudden cardiac death: A distinct clinical and electrocardiographic syndrome. A multicenter report. J. Am. Coll. Cardiol. 1992;20:1391–1396.
3. Antzelevitch C. The Brugada syndrome: Diagnostic criteria and cellular mechanisms. Eur. Heart J. 2001;22:356–363.
4. Brugada J, Brugada R, Brugada P. Right bundle branch block, ST-segment elevation in lead V1 through V3 and sudden cardiac death: A marker for sudden death in patients without demonstrable structural heart disease. Circulation. 1998;97:457–460.
5. Brugada P, Brugada J, Roy D. Brugada syndrome 1992–2012: 20 years of scientific excitement, and more. Eur. Heart J. 2013;34:3610–3615.
Pedro Brugada, MD, PhD Sergio Richter, MD | CASE 7.4 |
Patient History
This 12-lead ECG of a young male with recurrent syncope is normal. Administration of a sodium channel blocker (in this case ajmaline) unmasks the typical Brugada ECG pattern.
Figure 7.4.1
Discussion
Administration of a sodium channel blocker to unmask a possible Brugada syndrome is mandatory in all patients with syncope of unknown origin as well as in patients with isolated atrial fibrillation (atrial fibrillation may be the first manifestation of Brugada syndrome). Although ajmaline is preferred for this purpose, flecainide, procainamide, and pilsicainide are also used. This pharmacologic test can also be used to unmask family member carriers of the disease.
Figure 7.4.2 Phenocopies: Not all ECGs that look like Brugada syndrome are Brugada syndrome. Two examples of phenocopies are shown: A patient with pectus excavatum and a patient with a mediastinal tumor. Used with permission from Tarín et al. Pacing Clin. Electrophysiol. 1999;22:1264.
References
1. Brugada P. Brugada syndrome: More than 20 years of scientific excitement. J. Cardiol. 2016 Mar.;67(3):215–20.
2.
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