Diagnosis of Arrhythmogenic Right Ventricular Dysplasia‐Cardiomyopathy: Value of Standard ECG Revisited

Background: The diagnostic dilemma in arrhythmogenic right ventricular dysplasia‐cardiomyopathy (ARVD/C) is that a single diagnostic test does not exist and that there is a need for broadening diagnostic criteria. As standard ECG contributes significantly to clinical diagnosis and represents a tool for screening in family studies ECG data should be revisited. Methods and Results: In a cohort of 265 patients (159 males, mean age 46.8 years) with ISFC/ESC criteria of ARVD/C ECG features were reevaluated. QRS duration in (V1 + V2 + V3)/(V4 + V5 + V6) ≥ 1.2—called localized right precordial QRS prolongation—was present in 261/265 patients (98%) and represents the essential finding. Right precordial epsilon potentials were found in 23% in standard and in 75% in highly amplified and modified recording technique. Right precordial T wave inversions were present in 143 cases (54%) and ST‐segment elevation of different types in 66 patients (25%). Localized prolongation of inferior QRS complexes could be found in 58 cases (22%), complete right bundle branch block with T inversions beyond V2 in most cases in 17 patients (6%), incomplete right bundle branch block in 38 cases (14%), pseudo‐incomplete right bundle branch block in 8 patients (3%), and right precordial R wave reduction in 14 cases (5%). Conclusion: With regard to sensitivity and already known specificity an ECG score for the diagnosis of ARVD/C was developed with high probability of ARVD/C in cases with ≥4 points, possibly without the need for an additional imaging technique. Standard ECG with additional highly amplified and modified recording technique represents a single diagnostic test with high value in the clinical diagnosis of ARVD/C and should be used as a first line tool in noninvasive family screening.           A.N.E. 2003; 8(3):238‐245     

Special features of right bundle branch block in patients with arrhythmogenic right ventricular cardiomyopathy/dysplasia

We searched for special features in patients with complete and incomplete right bundle branch block diagnosed as having arrhythmogenic right ventricular cardiomyopathy/dysplasia. Whether right bundle branch block is a frequent finding in arrhythmogenic right ventricular cardiomyopathy should be studied. The question is whether special features exist such as T-wave inversions, localized right precordial QRS prolongation and r'/s ratio<1. RESULTS: ARVC could be diagnosed according to ISFC/ESC criteria in 374 patients. CRBBB was found in 22 cases (6%) and iCRBBB was present in 47 cases (12.5%). In CRBBB T wave inversions ≥ V4 was found in 10 cases (n.s.) and r'/s ratio<1 was present in 12 cases (p<0.001). In iCRBBB T wave inversions ≥ V4 was found in 10 cases (n.s.) and ST segment elevation in right precordial leads was present in 19 cases (p<0.005). In all patients with ARVC localized right precordial QRS prolongation was found. Patients with CRBBB have a bad prognosis: 17 of 22 patients developed biventricular heart failure requiring heart transplantation and diuretic therapy. CONCLUSIONS: CRBBB and iCRBBB are infrequent findings in arrhythmogenic right ventricular cardiomyopathy. Complete right bundle branch block is characterized by r'/s ratio<1. There are no significant T wave inversions ≥ V4. Incomplete right bundle branch block is characterized by ST segment elevation in right precordial leads but not by T wave inversions ≥ V4.     

致心律失常性右心室心肌病的心电图特征

目的探讨国人致心律失常性右心室心肌病患者临床心电图特征。方法分析32例致心律失常性右心室心肌病患者体表心电图各项参数。结果心电图记录到Epsilon波12例,QRS时间（V1＋V2＋V3）／（V4＋V5＋V6）≥1.2共15例,终末激动时间延长17例,出现QRS波群碎裂23例,可见异常Q波8例,V1～V3T波倒置且不存在束支传导阻滞14例,完全性右束支传导阻滞3例,不完全性右束支传导阻滞1例。28例记录到室性心动过速。结论Epsilon波、QRS时间（V1＋V2＋V3）／（V4＋V5＋V6）≥1.2、终末激动时间延长≥55ms及QRS波群碎裂是致心律失常性右心室心肌病特征性的体表心电图改变。     

ECG Features that suggest a potentially life-threatening arrhythmia as the cause for syncope

Syncope is a risk factor for sudden cardiac death (SCD) in many conditions associated with structural heart disease as well as inherited heart disease. The ECG in patients with syncope should be examined carefully for signs of structural heart disease, such as myocardial infarction or cardiomyopathy; signs of conduction system disease, such as bundle branch block or atrioventricular block; and signs of primary electrical disease. Important forms of cardiomyopathy accompanied by ECG changes include hypertrophic cardiomyopathy (HCM), and arrhythmogenic right ventricular dysplasia (ARVD/C). Common ECG findings in HCM include left ventricular hypertrophy by voltage, repolarization abnormalities, QRS widening, pseudoinfarction patterns, and slurred QRS upstroke mimicking delta waves. Classical ECG findings of ARVD/C include T-wave inversions and epsilon waves in the right precordial leads (V₁–V₃). Important forms of primary electrical disease which may result in syncope include Wolff–Parkinson–White syndrome, long QT syndrome, and Brugada syndrome, which is characterized by coved ST-segments in the right precordial leads, associated with a history of syncope, ventricular arrhythmia, or sudden cardiac death in probands or family member. There are three Brugada ECG patterns; however, only type I (spontaneous or induced) is considered diagnostic. Recently, studies have suggested that patients with J-point elevation or early repolarization pattern on ECG are at elevated risk of SCD. The clinical significance of finding early repolarization in a patient with syncope is unknown and should be a subject of future research.     

The Presence of Epsilon Waves in All Precordial Leads (V1–V6) in a 13‐Year‐Old Boy with Arrhythmogenic Right Ventricular Dysplasia (ARVD)

Electrocardiographic feature is included in the diagnostic criteria for arrthythmogenic right ventricular dysplasia (ARVD) based on the Revised Task Force criteria 2010. The epsilon wave, which reflects delayed conduction of the right ventricle, is considered to be one of the major diagnostic criteria. We reported a 13‐year‐old Thai boy with ARVD who presented with ventricular tachycardia. The presence of epsilon wave in all precordial leads (V₁–V₆) was observed in standard 12‐lead EKG. Extensive scarring of the right and left ventricle was seen on cardiac MRI. The extensive Epsilon wave found in this patient may reflect the extensive ventricular wall involvemen.     

The Electrocardiographic Manifestations of Arrhythmogenic Right Ventricular Dysplasia

The ECG is abnormal in most patients with arrhythmogenic right ventricular dysplasia (ARVD). Right ventricular parietal block, reduced QRS amplitude, epsilon wave, T wave inversion in V1-3 and ventricular tachycardia in the morphology of left bundle branch block are the characteristic changes that reflect the underlying genetic predetermined pathology and pathoelectrophysiology. Recognizing the characteristic ECG changes in ARVD will be of help in making a correct diagnosis of this rare disease.     

36例致心律失常性右室心肌病的心电图特征和临床观察

目的探讨致心律失常性右室心肌病(ARVC)的心电图特征和临床表现。方法回顾分析符合欧洲心脏病协会ARVC诊断标准的36例患者的心电图参数、临床表现、超声心动图、腔内电生理检查等临床资料。结果36例中男26例、女10例,年龄37±13岁;33例表现为心悸、胸闷,11例同时伴有晕厥,2例有家族性猝死史。心电图研究发现10例(28%)出现Epsilon波,29例(81%)右胸(V1～V3)导联QRS波时限≥110ms;在29例无右束支传导阻滞的患者中,右胸导联分别有16例(55%)出现T波倒置、18例(62%)出现S波升支时间≥55ms;17例(47%)QRSd1/QRSd2(V1～V3导联与V4～V6导联QRS波时间平均值之比)≥1.2;24例(67%)出现室壁阻滞;27例(75%)记录到持续性或非持续性室性心动过速。29例超声心动图表现为严重的右室受累。25例行腔内电生理检查,20例诱发出右室起源的室性心动过速,即刻射频消融成功11例。结论ARVC好发于青年男性,是引起晕厥、室性心律失常和室壁运动异常的重要原因,Epsilon波、右胸导联QRS波时限≥110ms与T波倒置、右室起源的室性心律失常为其特征性的心电图改变,QRSd1/QRSd2≥1.2、室壁阻滞、右胸导联S波升支时间≥55ms有助于该病的诊断,经导管射频消融治疗室性心动过速成功率低。     

Risk stratification of sudden cardiac death and malignant ventricular arrhythmias in right ventricular dysplasia-cardiomyopathy

Arrhythmogenic right ventricular dysplasia-cardiomyopathy is in most cases a benign cause of ventricular arrhythmias in young patients. The major reason of mortality is sudden arrhythmic death with an annual rate of 2-3% as the first manifestation of the disease in most cases. Little is known about risk factors of sudden arrhythmic death so far. The purpose of the retrospective study was to classify risk factors from invasive and non-invasive examinations. METHODS: In a cohort of 121 consecutive patients sampled from 1986 to 1998 the value of right ventricular dilatation, left ventricular involvement analysed by angiocardiography or echocardiography and standard ECG parameters such as precordial T wave inversions, right precordial ST elevation, precordial QRS dispersion, left precordial JT interval prolongation and complete right bundle branch block were determined. The whole cohort of patients were divided into two groups with high arrhythmic risk (aborted or non-aborted sudden death, recurrent ventricular tachycardia despite medical treatment, recurrent syncopes) and low risk (frequent ventricular premature beats, non sustained ventricular tachycardia, uneventful course under medical therapy). RESULTS: From angiocardiography or echocardiography in a quantitative approach right ventricular dilatation (p<0.0001) and additional left ventricular abnormalities (p<0.0001) could be identified as major risk factors. From an ECG point of view increased precordial QRS dispersion > or =50 ms (p<0.01) with complete right bundle branch block and right ventricular dilatation in most cases and precordial T wave inversions beyond V3 (p<0.0001) and the phenomenon of left precordial JT interval prolongation (JT dispersion > or =30 ms) in cases of additional left ventricular abnormalities represented non-invasive predictors of recurrent arrhythmic events. Right precordial ST segment elevation could be excluded as risk factor of sudden arrhythmic death. CONCLUSIONS: Right ventricular dilatation with ECG depolarisation abnormalities and additional left ventricular involvement with striking ECG repolarisation abnormalities could be identified as strong risk factors of recurrent arrhythmic events in ARVD with unfavorable prognosis.     

Epsilon Waves Detected by Various Electrocardiographic Recording Methods in Patients with Arrhythmogenic Right Ventricular Cardiomyopathy

We analyzed the shape and distribution of epsilon waves by 3 various methods of electrocardiographic recording in patients with arrhythmogenic right ventricular cardiomyopathy.Thirty-two patients who met recognized diagnostic criteria for arrhythmogenic right ventricular cardiomyopathy were included in this study (24 men and 8 women; mean age, 42.3 ± 12.9 yr). Epsilon waves were detected by standard 12-lead electrocardiography (S-ECG), right-sided precordial lead electrocardiography (R-ECG), and Fontaine bipolar precordial lead electrocardiography (F-ECG). We found 3 types of epsilon waves: wiggle waves, small spike waves, and smooth potential waves that formed an atypical prolonged R'' wave. The most common configuration was small spiked waves. In some circumstances, epsilon waves were evident in some leads (especially in leads V₁ through V₃), but notches were recorded in the other leads during the corresponding phase. These waves could be detected only by S-ECG in 1 patient, R-ECG in 3 patients, and F-ECG in 5 patients; the rates of epsilon-wave detection by these 3 methods were 38% (12/32), 38% (12/32), and 50% (16/32), respectively. However, the detection rate using combined methods was significantly higher than that by S-ECG alone (SF-ECG 56% vs S-ECG 38%, P = 0.0312; and SRF-ECG 66% vs S-ECG 38%, P = 0.0039). In addition, the rate of widespread T-wave inversion (exceeding V₃) was significantly higher in patients with epsilon waves than in those without (48% vs 9%, P = 0.029), as was ventricular tachycardia (95% vs 64%, P = 0.019).These 3 electrocardiographic recording methods should be used in combination to improve the detection rate of epsilon waves.Key words: Arrhythmias, cardiac/etiology; arrhythmogenic right ventricular dysplasia/diagnosis; cell communications/genetics; electrocardiography/methods/standards; epsilon waves; gap junctions; genetic predisposition to disease; heart function tests; sensitivity and specificity; ventricular dysfunction, rightArrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited heart-muscle disease that predominantly affects the right ventricle (RV), especially the triangle of dysplasia. It is characterized pathologically by RV myocardial atrophy with fibrofatty replacement and clinically by ventricular electric instability with ventricular tachycardia (VT) or ventricular fibrillation that may lead to sudden death, primarily in young people and athletes.^1,2 Epsilon waves are an important diagnostic clue for ARVC. Peters and colleagues³ found the prevalence of epsilon waves to be 23% in standard 12-lead electrocardiography (S-ECG) and 75% in Fontaine bipolar precordial lead ECG (F-ECG). In the present study, we applied jointly the S-ECG, right-sided precordial lead ECG (R-ECG), and F-ECG to analyze preliminarily the shape and distribution of epsilon waves, and to compare the impact of the various methods of ECG recording on the detection rate of epsilon waves.     

致心律失常性右心室心肌病一家系报告

目的 探讨家族性致心律失常性右心室心肌病的心电图特点。方法报道致心律失常性右心室心肌病患者一家系并结合文献分析其特点。结果本家系中右心室心肌病的发病率很高,男女患病比例相仿,疾病的表现度有较大的可变性,有时可无症状。先证者心电图发现Epsilon波且以V3R最为明显,所有患者V1～V3QRS波群终末部均有挫折,QRS时间均〉110ms,V3～V4均有T波倒置现象。结论致心律失常性右心室心肌病存在明显的遗传倾向,临床上以室性心律失常及猝死为主要表现,心电图具有相对特征性改变。     

The value of different electrocardiographic depolarization criteria in the diagnosis of arrhythmogenic right ventricular dysplasia/cardiomyopathy

Background

The use of electrocardiographic (ECG) depolarization and repolarization criteria plays a large role in the diagnosis of arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C). Different ECG algorithms should be analyzed in making the diagnosis of ARVD/C with the use of normal and modified recording techniques.

Methods

In a cohort of 343 patients (210 men and 133 women; mean age, 46.0 ± 13.7 years) meeting the Task Force of the Working Group on Myocardial and Pericardial Diseases of the European Society of Cardiology and the Scientific Council on Cardiomyopathies of the International Society and Federation of Cardiology diagnostic criteria for ARVD/C, the value of different ECG criteria (eg, localized right precordial QRS prolongation defined as QRS duration in (V1+V2+V3)/(V4+V5+V6) of 1.2 or higher, right precordial QRS prolongation with QRS in V1-3 of 110 milliseconds or higher, epsilon potentials in the right precordial leads, S-wave upstroke in V1-3 of 55 milliseconds or higher, and right precordial T-wave inversions) was analyzed with the use of a normal recording technique and a highly amplified and modified recording technique (n = 207) at a paper speed of 50 mm/s. Fifty-two phenotypically and genotypically unaffected individuals identified by systematic screening in 24 families (30 men; mean age, 42.4 ± 8.3 years) were treated as control subjects.

Results

In the normal as well as highly amplified and modified recording techniques, the incidence of localized right precordial QRS prolongation was 98% (100%), that of QRS in V1-3 of 110 milliseconds or higher was 75% (80%), that of prolonged right precordial S-wave upstroke was 84% (60%), that of epsilon potentials was 23% (77%), and that of right precordial T-wave inversions was 55%. Four of 6 patients without the phenomenon of localized right precordial QRS prolongation with the use of the normal recording technique had a prolonged S-wave upstroke of 55 milliseconds or higher. In the control group, localized right precordial QRS prolongation, QRS in V1-3 of 110 milliseconds or higher, and epsilon potentials could not be identified. An S-wave upstroke of 55 milliseconds or higher was present in 2 of 3 cases, and T-wave inversions were found in 3.

Conclusions

Electrocardiographic depolarization criteria for ARVD/C analyzed in this large cohort of patients meeting the International Society and Federation of Cardiology/European Society of Cardiology criteria presented with high sensitivity and specificity in comparison with those in the control group of phenotypically and genotypically unaffected individuals defined by systematic screening in 24 families with ARVD/C. The incidence of right precordial T-wave inversions was much lower, indicating that not only patients with overt right ventricular dilatation and dysfunction were included. Electrocardiographic algorithms, including localized right precordial QRS prolongation, prolonged S-wave upstroke, and epsilon potentials, with the use of the normal recording technique and the amplified and modified recording technique at a paper speed of 50 mm/s contribute significantly to the noninvasive diagnosis of ARVD/C.     

When should we diagnose incomplete right bundle branch block?

An rSr' pattern with QRS duration of less than 0.12 s in theright precordial leads can be due to incomplete right bundlebranch block (which may progress to complete right bundle branchblock) or can be a normal electrophysiological variant. To identifyother ECG features that may help to distinguish between thesetwo possibilities, ECGs of 15 patients who progressed from normalto complete right bundle branch block through an intermediaterSr' pattern of incomplete right bundle branch block were analysed.The following features in the right precordial leads (V₁, V₂)that preceded or accompanied the appearance of the rSr' wereidentified: diminution of the S wave depth (100%), inversionof ratio of the S wave depth to SV₁,/SV₂ (93%), slurring ofthe downstroke or upstroke of the S wave (27%) and prolongationof the QRS duration to 0.10 s (73%). When a further 79 subjectswith rSr' pattern in the right precordial leads and QRS durationof <0.12 s were divided into those with SV₁/SV₂ ratio >1.0 and those with SV₁/SV₂ < 1.0, compared with the latterthe subjects with SV₁/SV₂ ratio > 1.0 were found to be significantlyolder (59.8±18.4 years vs 32.8±18.1 years, P<0.001),to exclusively show S wave slurring (37% vs 0%), and to morelikely have a QRS duration 0.10s (74% vs 7%). The findings indicatethat when faced with a single ECG showing an rSr' pattern inthe right precordial leads and QRS duration 0.12 s, severalother features, and in particular the relative sizes of theS waves in V₁ and V₂, may be useful in distinguishing rSr' dueto incomplete right bundle branch block from ‘normal’rSr'.     

Right Ventricular Infarction Mimicking Anterior Infarction

It is rare to observe ST elevation in anterior derivations caused by right ventricular branch occlusion. We described the case of a patient with unstable angina who developed acute right ventricular myocardial infarction with ST‐segment elevation in anterior precordial leads (V₁–V₄) shortly after coronary angiography. Coronary angiogram revealed total occlusion of the right coronary artery (RCA) proximally to the right ventricular branch. This reminds us that the presence of diffuse ST‐segment elevation in the precordial leads could be due to acute RCA occlusion. The differentiation of these two entities is important, as their therapies are quite different.     

The Presence of Giant Epsilon Waves in a Patient with Arrhythmogenic Right Ventricular Cardiomyopathy

Epsilon wave, which is a major diagnosis criterion for arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVD/C), is defined as small amplitude potentials. The present case is a 49‐year‐old man with a history of syncope and palpitations for 6 months. The ECG documented ventricular tachycardia (VT) when the patient has palpitations. However, there has been a giant epsilon wave in sinus rhythm. Electroanatomic mapping also has a prominent double potential identified on ABL catheter. The amplitude of epsilon wave reached 0.9 mV, which might be the maximum epsilon wave until now.     

Epicardial Macro-Reentrant Ventricular Tachycardia Exhibiting an Endocardial Centrifugal Activation Pattern in a Case with Arrhythmogenic Right Ventricular Cardiomyopathy

A 55-year-old man with arrhythmogenic right ventricular cardiomyopathy underwent catheter ablation of ventricular tachycardia (VT) with left bundle branch block and left superior axis QRS morphology with an early precordial transition. Endocardial mapping during the VT revealed a focal activation pattern from a small region of low voltage in the left ventricular (LV) septum. Despite earliest endocardial activation in the LV septum, epicardial mapping demonstrated a macro-reentrant circuit with successful catheter ablation at an inferior peritricuspid annular site. Activation from the reentrant circuit propagated through the scar area in the epicardial right ventricle to the remote endocardial LV breakout site.     

心电图评价致心律失常性右心室心肌病病变程度的临床价值

目的 分析致心律失常性右心室心肌病(ARVC)患者的病变程度与心电图表现之间的关系.方法 分析61例已确诊的ARVC患者,根据心脏核磁共振成像(MRI)检查结果,将其按病变侵犯部位分为右心室局部病变组、右心室弥漫病变组、双心室病变组,分析比较三组的心电图特征.结果 心脏MRI结果显示右心室局部病变组19例(31%),右心室弥漫病变组28例(46%),双心室病变组14例(23%).心电图正常者3例,三组中各1例.伴有Epsilon波的患者24例(39%)、V1～V3导联的QRS波时限≥110 ms的患者21例(34%)、V1～V3导联S波升支≥55 ms的患者17例(28%)、完全右束支传导阻滞的患者10例(16%)、病理性Q波的患者9例(15%),这些指标的发生率均随病变程度的加重而增高(右心室局部病变组＜右心室弥漫病变组＜双心室病变组).Epsilon波、V1～V3导联的QRS波时限≥110 ms、完全性右束支传导阻滞(RBBB)、病理性Q波的发生率在双心室病变组中要高于右心室局部病变组,且两组间比较差异有统计学意义(P＜0.05).V1～V3导联S波升支≥55 ms的发生率在双心室病变组中要高于右心室局部病变组,且两组间比较差异有统计学意义(P＜0.05);在双心室病变组要高于右心室弥漫病变组,且两组间比较差异均有统计学意义(P均＜0.05).一度房室传导阻滞的发生率在双心室病变组中要高于右心室弥漫病变组,且两组间比较差异有统计学意义(P＜0.05).右心室局部病变组患者心电图T波倒置多局限于V1导联,右心室弥漫病变组和双心室病变组T波倒置多数表现于胸前导联V1～V3或超过V3导联的胸前导联、以及下壁导联.结论 心电图正常并不能排除ARVC.ARVC患者T波倒置在12导联心电图上具有很高的发生率,并且T波倒置在胸部导联的延伸与病变程度是相关的,T波倒置的范围可以提示ARVC病变累及的程度.

Abstract：

Objective To analyze the relationship between electrocardiographic (ECG) features and disease severity in patients with the arrhythmogenic right ventricular cardiomyopathy (ARVC). Method The study group consisted of 61 subjects with a definite diagnosis of ARVC on the basis of published guideline criteria and patients were divided into 3 subgroups according to the extent of diseased myocardium defined by cardiac magnetic resonance imaging (MRI): Group A: local involvement (n = 19, 31% ), Group B: diffuse involvement of whole right ventricle ( n = 28, 46% ) and Group C: involvement of both right and left ventricles ( n = 14, 23% ). Results Normal electrocardiogram was shown in 1 patient in each group.Epsilon wave was detected in 24 (39%) patients, QRS duration was prolonged [≥ 110 ms( V1 -V3 )] in 21 (34%) patients, S-wave upstroke was prolonged (≥55 ms) in 17 (28%) patients, complete right branch bundle block was evidenced in 10 ( 16% ) patients and pathologic Q waves was found in 9 ( 15% ) patients. The incidence of above abnormal ECG changes was increased in proportion to the degree of disease severity (group A ＜ group B ＜ group C). Incidence of Epsilon wave and prolonged QRS duration [≥ 110 ms (V1 - V3 )] were significantly higher in Group C than in Group A. Incidence of prolonged S-wave upstroke ( ≥55 ms) was significantly higher in Group C than in Group A and Group B. T-wave inversion in V1 leads was often found in Group A. T-wave inversion in inferior leads ( V1 - V3 leads or beyond V3 ) was often presented in Group B and Group C. Conclusions Normal ECG does not exclude the possibility of diagnosis of ARVC. The extent of T-wave inversion in the precordial leads and incidence of Epsilon wave, prolonged QRS duration [≥ 110 ms (Vt -V3 )] and prolonged S-wave upstroke ( ≥55 ms) were related to degree of disease severity in patients with ARVC.     

Right bundle branch block: electrocardiographic and prognostic features

The electrocardiographic appearances and the significance of right bundle branch block were described at the beginning of the 20th century. Typical appearances include prolongation > 0.12 s of the QRS complex, RR' or rR' or Rr' appearances in V1 and widened S waves in the leads exploring the left ventricle (SI, aVL, V5 and V6). A delay in the appearance of the intrinsic deflection > 0.08 s may also be observed in the right precordial leads and negative T waves with ST depression may be seen in V1 and sometimes in V2. Left axis deviation of the QRS complex greater than - 45 degrees suggests associated left anterior hemiblock. Right axis deviation beyond + 120 degrees is equivocal. The principal differential ECG diagnosis is the Brugada syndrome, a familial arrhythmogenic autosomal dominant cardiomyopathy of variable penetration. This diagnosis is suggested when ECG abnormalities are observed in patients with a personal or family history of sudden death. Right bundle branch block only seems to have haemodynamic consequences in cardiac failure with associated asynchrony of the left ventricle or in certain cases of right ventricular dilatation encountered in congenital heart disease. The prognosis of right bundle branch block in the absence of underlying cardiac disease is good but it may be poor in other cases, particularly coronary artery disease. Moreover, the prognosis of right bundle branch block to complete atrioventricular block is rare in the absence of associated cardiac disease.     

Characteristics of ventricular tachycardia arising from the inflow region of the right ventricle

IntroductionVentricular tachycardia (VT) arising from the right ventricular inflow (RVI) region is uncommon. There is minimal literature on the clinical and electrocardiographic characteristics of RVI VT.MethodsA retrospective analysis of patients with RVI VT who underwent electrophysiology study between 2006 and 2011 was performed. Patients with structural heart disease (including arrhythmogenic right ventricular dysplasia) were excluded.ResultsSeventy patients underwent an electrophysiology study for VT arising from the right ventricle during the study period. Nine patients (13%) met the inclusion criteria for RVI VT and were the subject of this analysis. The median age was 46 years (range, 14-71), and VT cycle length was 295 milliseconds (range, 279-400 milliseconds). All VTs had an left bundle-branch block morphology. An inferiorly directed QRS axis was noted in 7 (78%) of 9 patients and a left superior axis in 2 (22%) of 9 patients. A QS or rS pattern was noted in all patients in aVR and V₁. A transition from S to R wave occurred in V₃ to V₅ in all patients, with 78% of the patients transitioning in V₄ or V₅. Ablation was attempted in 8 (89%) of 9 patients and was successful in 6 (67%) of 9 patients. Ablation was limited in all unsuccessful patients due to the proximity to the His and risk of complete heart block.ConclusionsElectrocardiographic findings of a left bundle-branch block with a normal QRS axis, QS or rS patterns in aVR and V₁, and late S to R transition (V₄/V₅) are commonly found in RVI VT. Because of the proximity to the His, ablation of RVI VT may be more challenging than that of right ventricular outflow tract VT.