Concordance of distinguishing electrocardiographic features during sinus rhythm with the location of accessory pathways in the Wolff-Parkinson-White syndrome

Knowledge of the location of accessory pathways in patients with Wolff-Parkinson-White (WPW) syndrome is pertinent to patient management. Despite the recognition that features of delta waves present during maximal preexcitation reflect ventricular activation at different sites around the anulus fibrosus, the value of electrocardiographic patterns observed during sinus rhythm, when ventricular preexcitation is often not maximal for identifying accessory pathway locations, has not been determined. In this study, 12-lead electrocardiograms recorded during sinus rhythm from 66 patients with WPW syndrome were analyzed for delta-wave polarity, QRS axis in the frontal plane, the pattern of precordial R-wave transition, and concordance between electrocardiographic patterns and the site of the accessory pathway determined using catheter and intraoperative computer mapping. Electrocardiograms from patients with left lateral sites showed negative delta waves in leads I or aVL, a normal QRS axis and early precordial R-wave transition (20 of 24 patients); left posterior sites manifested negative delta waves in II, III and aVF and a prominent R wave in V1 (14 of 16 patients); posteroseptal sites had negative delta waves in II, III and aVF, a superior QRS axis and an R less than S in V1 (all 16 patients); right free wall locations manifested negative delta waves in aVR, a normal QRS axis, and R-wave transition in V3-V5 (6 of 6 patients); and anterior septal sites had negative delta waves in V1 and V2, a normal QRS axis, and R-wave transition in V3-V5 (4 of 4 patients). Characteristic electrocardiographic patterns were not observed in 5 patients because of insufficient preexcitation. Each had a left lateral or left posterior pathway. Overall, the proposed electrocardiographic criteria derived during sinus rhythm identified correctly the accessory pathway location in 60 of 66 patients (91%). Thus, the electrocardiogram provides the physician with a reliable noninvasive means of regionalizing the location of accessory pathways in patients with WPW syndrome.     

Electrocardiographic and electrophysiologic characteristics of midseptal accessory pathways

BACKGROUND : The purpose of the present study was to investigate the electrocardiographic and electrophysiologic characteristics of right midseptal (RMS) and left midseptal (LMS) accessory pathways (APs), and to develop a stepwise algorithm to differentiate RMS from LMS APs. METHODS AND RESULTS: From May 1989 to February 2004, 1591 patients with AP-mediated tachyarrhythmia underwent RF catheter ablation in this institution, and 38 (2.4%) patients had MS APs. The delta wave and precordial QRS transition during sinus rhythm, retrograde P wave during orthodromic tachycardia, and electrophysiologic characteristic and catheter ablation in 30 patients with RMS APs and 8 patients with LMS APs were analyzed. There was no significant difference in electrophysiologic characteristics and catheter ablation between RMS and LMS APs. The polarity of retrograde P wave during orthodromic tachycardia also showed no statistical difference between patients with RMS and LMS APs. The delta wave polarity was positive in leads I, aVL, and V3 to V6 in patients with RMS and LMS APs. Patients with LMS APs had a higher incidence of biphasic delta wave in lead V1 than patients with RMS APs (80% vs. 15%, P=0.012). The distributions of precordial QRS transition were different between RMS APs (leads V2; n = 10, V3; n = 7 and V4; n = 3) and LMS APs (leads V1; n = 1 and V2; n = 4) (P = 0.03). The combination of a delta negative wave in lead V1 or precordial QRS transition in lead V3 or V4 had a sensitivity of 90%, specificity of 80%, positive predictive value of 95%, and negative predictive value of 66% in predicting an RMS AP. CONCLUSIONS: Delta wave polarity in lead V1 and precordial QRS transition may differentiate RMS and LMS APs.     

An electrocardiographic algorithm for determining the location of pacemaker electrode in patients with right bundle branch block configuration during permanent ventricular pacing

The expected morphology of right ventricular pacing is a left bundle branch block (LBBB) pattern. However, right bundle branch block (RBBB) can also be seen during permanent right ventricular pacing. The aim of this study was to develop an electrocardiographic algorithm to differentiate this benign condition from septal and free wall perforation with subsequent left ventricular pacing. Three hundred consecutive patients who had permanent ventricular or dual-chamber pacemaker implantation between 1999 and 2000 were screened and 25 patients (8.3%) who exhibited RBBB configuration were included in the study. Echocardiograms and chest radiographs were evaluated in order to identify the pacing lead location in this group. The authors formed a study group with their own 25 patients and 22 cases of RBBB with permanent pacemaker from previous publications (total 47 patients). Frontal axis, QRS morphology in lead V(1), and the precordial transition point, which is defined as the precordial lead where R wave amplitude is equal to S wave amplitude, were examined. Placement of precordial leads V(1) and V(2) 1 interspace lower than the standard location (Klein maneuver) eliminated the RBBB pattern in 12 patients. RBBB pattern with "true right ventricular pacing" was detected in 24 of the 25 patients, and in 11 of the 22 patients reported in the literature (total 35 patients). Right ventricular pacing was correctly identified in 34 of 35 patients with use of criteria including left superior axis deviation, RS or qR morphology in lead V(1), and precordial transition at lead V(3) with a high sensitivity and specificity. A simple surface electrocardiogram can accurately predict the lead location in patients having RBBB morphology with right ventricular pacing.     

形态心电图标准在原有束支阻滞伴宽QRS波群心动过速鉴别诊断中的特异性评价

为探讨形态心电图标准是否适用原有束支阻滞（ＢＢＢ）或心肌梗塞患者合并宽ＱＲＳ波群心动过速的鉴别诊断,选择窦性心律呈ＢＢＢ的患者２０５例［左束支阻滞（ＬＢＢＢ）４５例、右束支阻带（ＲＢＢＢ）１６０例］,分析形态心电图标准用于鉴别宽ＱＲＳ波群心动过速的特异性。胸导联ＱＲＳ波群图形一致、胸导联无ＲＳ型;ＲＢＢＢ时任一胸导联ＲＳ时限＞１００ｍｓ,Ｖ１导联单向（Ｒ）或双向（ｑＲ、ＱＲ、ＲＳ）、呈左兔耳征,Ｖ６导联或ａＶＦ导联Ｑ波,Ｖ６导联Ｒ／Ｓ＜１;ＬＢＢＢ时,Ｖ１、Ｖ２导联ｒ波时限＞３０ｍｓ,Ｖ１、Ｖ２导联Ｓ波降支钝挫,Ｖ６导联或ａＶＦ导联ｑ（Ｑ）波等１２条特异性较高。ＱＲＳ波群时限＞１４０ｍｓ;ＲＢＢＢ时电轴重度左、右偏,ａＶＦ导联Ｒ／Ｓ＜１;ＬＢＢＢ时Ｖ１、Ｖ２导联ＲＳ时限＞６０ｍｓ,Ⅰ导联负向ＱＲＳ波群,Ｖ４较Ｖ１导联Ｓ波振幅更深等７条特异性较低。心肌梗死合并宽ＱＲＳ波群心动过速时采用上述标准鉴别诊断有一定局限。     

左束支阻滞型特发性室性心动过速的心电图特征对射频消融成功的影响初探

对心电图呈左束支阻滞型的特发性室性心动过速 (简称室速 )的临床特点和心电图进行分析 ,以了解哪些因素可以预测此类患者从右室流出道行射频消融的成功率。对 2 6例特发性室速的患者进行电生理检查和射频消融手术 ,全部患者室速时的心电图呈左束支阻滞。结果 :2 6例中 ,2 2例于右室流出道进行了成功消融 ,成功和未成功消融的患者临床特征和电生理无明显区别 ,成功消融的患者中胸前V1 导联心电图呈rS型 (1 2例 )和QS型 (1 0例 ) ,而 4例未成功者 ,V1 导联均呈rS型 ,其中 2例经主动脉于左冠状窦消融成功。在成功与未成功消融患者中 ,V1 导联有无R波无明显区别 ,但V1 导联无R波预示室速可以从右室流出道成功消融 ,成功消融的室速患者胸前导联的平均移行区在V4导联 ,而未成功患者胸前导联的移行区在V3 或V2 导联。结论 :某些心电图呈左束支阻滞 ,且额面电轴正常或右偏的特发性室速患者不能成功从右室流出道消融 ,V1 导联有r波且移行区在V3 导联或之前者提示此类心电图特征的室速可能非起源于右室流出道 ,部分可能起源于左室流出道     

Prevalence and electrocardiographic forms of the Wolff-Parkinson-White syndrome

In a routine electrocardiographic study of 133929 subjects aged from 20 to 73, 136 cases of the Wolff-Parkinson-White syndrome were detected, 6 with intermittent pre-excitation. In this study, the prevelance of WPW was about 1 in a 1000, the highest incidence being in the 20-40 year age group with an equal sex ratio. The ECG analysis of the 136 cases consisted in determining the orientation of the delta wave in the precordial leads to establish the right or left ventricular origin of the pre-excitation, calculating the direction of the delta wave vector in the frontal plane to find out the anterior, lateral or posterior origin of the pre-excitation and analyse the position of the QRS axis to assess the appearances of the latest ventricular activity. The 136 ECGs were then classified according to electrophysiological criteria and the results of mapping: 1. Left ventricular pre-excitation; 74 cases characterised by a dominant delta wave in the right precordial leads. These cases were subdivided into: - 30 cases with posterior paraseptal pre-excitation, axis of the delta wave deviated superiorly and to the left, between -30 degrees and -60 degrees; - 20 cases of lateral pre-excitation with the vector of the delta wave deviated inferiorly and to the right between +100 degrees and +120 degrees; - 24 cases of anterior paraseptal pre-excitation with high amplitude delta and QRS deflections in all precordial leads and a delta wave axis between +50 degrees and +80 degrees. 2. Right ventricular pre-excitation; 62 cases characterised by a negative or isoelectric delta wave in the right precordial leads, including: - 14 posterior paraseptal pre-excitation with significant delta wave axis deviation between -30 degrees and -60 degrees; - 33 lateral pre-excitation with the delta and QRS axis pointing directly to the left at about 0 degrees; - 15 cases of anterior paraseptal pre-excitation with the delta wave axis between +50 degrees and +80 degrees. The cases with terminal forces of left ventricular activation in the same direction as the delta wave, superiorly and to the left at -60 degrees or inferiorly and to the right at +120 degrees, forming a single deflection of over 0,12 seconds' duration, are the result of delayed activation of the anterior or posterior fascicle of the left bundle after a long delay. On the other hand, the cases in which the direction of the pre-excitation is the same but the final part of ventricular activation moves away from the delta are probably the result of tension between the activation of the normal and accessory pathways.     

An unusual bundle-branch block

We report a case of right bundle-branch block (RBBB) showing a QRS configuration typical for left bundle-branch block (LBBB) in leads V(5) and V(6). The QRS axis was at +90 degrees, and the QRS duration was 0.14 second. There were wide S waves in leads I and aVL, suggesting at first glance an RBBB, but the QRS morphology in the inferior leads (monophasic R wave with secondary ST-T changes) was more consistent with an LBBB. Lead V(1) suggested an RBBB, whereas leads V(5) and V(6) showed a monophasic R wave as in LBBB; moreover, a negative T wave, typical of LBBB, was present in lead V(5). Placement of the electrodes of leads V(4), V(5), and V(6) 2 intercostal spaces above restored in these leads a QRS configuration suggestive of RBBB. The diagnostic problem was mainly caused by the inferior direction of the QRS axis. Because the electrode of V(6) is normally placed below the electrical center of the heart, namely, on a plane that is not orthogonal to the sagittal plane, a vector directed mainly inferiorly and slightly to the right does not project on the negative part but on the positive of the lead line. For this reason, the S waves normally observed in the left precordial leads with RBBB disappear. The superior displacement of the electrodes "normalizes" the plane upon which the lead lines lie, thereby restoring the expected QRS configuration.     

Ventricular tachycardias mimicking those arising from the right ventricular outflow tract

INTRODUCTION: Ablation of ventricular tachycardia (VT) arising from the right ventricular outflow tract (RVOT) has proven highly successful, yet VTs with similar ECG features may originate outside the RVOT. METHODS AND RESULTS: We reviewed the clinical, echocardiographic, and ECG findings of 29 consecutive patients referred for ablation of monomorphic VT having a left bundle branch block pattern in lead V1 and tall monophasic R waves inferiorly. Nineteen patients (group A) had VTs ablated from the RVOT, and 10 patients (group B) had VTs that could not be ablated from the RVOT. The QRS morphology during VT or frequent ventricular premature complexes was the only variable that distinguished the two groups. During the target arrhythmia, ECGs of group B patients displayed earlier precordial transition zones (median V3 vs V5; P < 0.001), more rightward axes (90 +/- 4 vs 83 +/- 5; P = 0.002), taller R waves inferiorly (aVF: 1.9 +/- 1.0 vs 2.4 +/- 0.5; P = 0.020) and small R waves in lead V1 (10/10 vs 9/19; P = 0.011). Radiofrequency catheter ablation from the RVOT failed to eliminate VT in any group B patient, but ablation from the left ventricular outflow tract (LVOT) eliminated VT in 2 of 6 patients in whom left ventricular ablation was attempted. CONCLUSION: The absence of an R wave in lead V1 and a late precordial transition zone suggest an RVOT origin of VT, whereas an early precordial transition zone characterizes VTs that mimic an RVOT origin. The latter VTs occasionally can be ablated from the LVOT. Recognition of these ECG features may help the physician advise patients and direct one's approach to ablation.     

正常人右胸导联心电图T波形态的性别差异

目的探讨正常人右胸导联心电图男女T波形态差异规律及临床意义。方法测量240名正常人右胸导联心电图,比较男女T波形态及变化规律。结果Vl→V3R→V6R直立T波出现率逐渐减少,倒置T波出现率逐渐增多。女性以倒置T波为主,男性以直立T波多见,差异有显著意义(P<0.01)。V1→V6R的T波变化规律:可均倒置,女性多于男性(P<0.01);也可由直立→双相→平坦→倒置,男性多于女性(P<0.01),但未见由倒置→直立。结论正常人右胸导联心电图T波形态男女差异显著,应引起临床注意。     

Electrocardiogram in patients with fasciculoventricular pathways: a comparative study with anteroseptal and midseptal accessory pathways.

OBJECTIVES: The purpose of this study was to describe the ECG profile of a cohort of patients with fasciculoventricular pathways and compare the profile with the ECG of patients with anteroseptal and midseptal accessory pathways. BACKGROUND: Electrophysiologic findings suggest fasciculoventricular pathways insert into the septal region. Findings also suggest the 12-lead surface ECG during sinus rhythm is similar to the ECG of patients with anteroseptal and midseptal bypass tracts. METHODS: Four different observers analyzed the 12-lead ECG of seven patients with fasciculoventricular pathways (group I) and the ECG of 20 patients with midseptal AV accessory pathways (group II) and 20 patients with anteroseptal AV accessory pathways (group III). The following variables were analyzed: ECG frontal plane QRS and delta wave axis; angle between the QRS and the delta wave axis; QRS width; R/S ratio in lead III; presence of a negative delta wave in inferior leads; and precordial lead transition to R/S >1. RESULTS: The ECG of fasciculoventricular pathways shows a variable pattern. It shares some features with an anteroseptal accessory pathway and others with a midseptal accessory pathway. A narrower QRS width was the most important variable in distinguishing a fasciculoventricular pathway from a septally located AV bypass tract (P <.0001). The angle between the QRS and the delta wave frontal plane axis could differentiate a fasciculoventricular pathway from an anteroseptal bypass tract (P <.0001) but not from a midseptal accessory pathway. CONCLUSIONS: The sinus rhythm ECG of patients with fasciculoventricular pathways shows similarities with ECGs of patients with anteroseptal and midseptal accessory pathways, but the QRS complex usually is narrower. The ECG recorded during sinus rhythm cannot reliably differentiate fasciculoventricular pathways with a broad QRS complex from anteroseptal or midseptal bypass tracts.     

Radiofrequency catheter ablation of upper septal idiopathic left ventricular tachycardia exhibiting left bundle branch block morphology

Idiopathic left ventricular (LV) tachycardia usually exhibits right bundle branch block morphology. There are only a few sporadic cases that exhibit left bundle branch block (LBBB) morphology. We report a patient whose QRS complex during ventricular tachycardia (VT) was relatively narrow (100 msec) and exhibited LBBB (precordial R wave transition between V3 and V4) and a normal frontal plane axis. This VT was ablated successfully by radiofrequency current applied to the LV upper septum, where the earliest endocardial activation was recorded.     

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.     

Surface electrocardiographic clues suggesting presence of a nodofascicular Mahaim fiber

Standard electrocardiograms from 87 consecutive patients with tachycardia of left bundle branch block configuration were analyzed retrospectively for features that might be characteristic of tachycardia utilizing a nodofascicular Mahaim fiber. The study group consisted of 13 patients with nodofascicular tachycardia, 34 with supraventricular tachycardia and aberrant conduction over the His-Purkinje system, 22 with ventricular tachycardia and 18 with antidromic tachycardia utilizing a right-sided accessory atrioventricular pathway. Six variables present during tachycardia of left bundle branch block configuration were predictive of a nodofascicular fiber: cycle length between 220 and 450 ms, QRS axis of 0 to -75 degrees, QRS duration 0.15 second or less, R wave in lead I, rS wave in precordial lead V1 and a precordial transition from a negative to a positive QRS complex after lead V4. All six criteria were present in 16 of the 87 patients. No patient with ventricular tachycardia satisfied these criteria, whereas 3 of 34 with supraventricular tachycardia, 1 of 18 with antidromic tachycardia and 12 of 13 with tachycardia using a nodofascicular fiber did. It is concluded that analysis of the surface electrocardiogram during tachycardia may suggest the presence of a nodofascicular fiber.     

Electrocardiographic associations of right precordial Q waves help to distinguish anterior myocardial infarction from aortic stenosis

Right precordial Q waves are ECG evidence of anterior myocardial infarction and can be present in patients with pathological left ventricular hypertrophy particularly caused by aortic stenosis. The aim of this study was to investigate the ECG features associated with Q waves in aortic stenosis and those in anterior myocardial infarction. We studied 16 patients with anterior myocardial infarction and 19 patients with aortic stenosis by means of ECG, echocardiography and clinical history. On the ECG, heart rate (70 +/- 20 beats/min vs. 83 +/- 20) and QT interval (380 +/- 65 ms vs. 390 +/- 50) did not differ between the two conditions. PR interval (160 +/- 15 ms vs. 185 +/- 30, P<0.05) and QRS duration (80 +/- 7.0 ms vs. 95 +/- 15, P<0.01) were both longer in patients with aortic stenosis than in those with myocardial infarction. The Q wave voltage in V1 (1.0 +/- 0.55 mV vs. 1.5 +/- 0.60) or V2 (1.3 +/- 0.5 mV vs. 1.8 +/- 0.85) and R wave voltage in V5 (0.7 +/- 0.7 mV vs. 2.1 +/- 0.9) or V6 (0.7 +/- 0.4 mV vs. 1.5 +/- 0.7, all P<0.01) were significantly less in patients with anterior myocardial infarction than in those with aortic stenosis. Q wave voltage over 1.3 mV in V1 or R wave voltage over 1.5 mV in V5 can differentiate aortic stenosis from anterior myocardial infarction with a sensitivity of 79% for each and specificities of 81 and 93.8%, respectively. Though the frontal QRS axis was similar in the two groups (28 +/- 45 degrees vs. 14 +/- 35, P>0.05), the horizontal QRS axis pointed laterally (-30 +/- 20 degrees) in aortic stenosis and posteriorly (-60 +/- 20 degrees, P<0.01) in anterior myocardial infarction. A horizontal QRS axis between zero and -45 degrees detected the presence of aortic stenosis with a sensitivity of 94.7% and a specificity of 81.3%. On echocardiography, left ventricular hypertrophy was found in most patients (94.7%) with aortic stenosis but not in those (0%) with anterior myocardial infarction. Left ventricular end diastolic dimensions (5.1 +/- 0.7 cm vs. 5.1 +/- 0.9, P>0.05) were similar in the two groups but the end systolic dimension was increased in patients with aortic stenosis (4.0 +/- 0.9 cm vs. 3.4 +/- 0.6, P<0.05). The systolic left ventricular function (shortening fraction: 23 +/- 8.0% vs. 34 +/- 7.0; Vcf: 0.8 +/- 0.26 circ/s vs. 1.3 +/- 0.26, both P<0.01) was significantly impaired in patients with aortic stenosis compared to those with myocardial infarction. In conclusion, in the presence of right precordial Q waves, the simple 12-lead ECG can provide important information on distinguishing anterior myocardial infarction from aortic stenosis. In particular, the QRS voltage in the chest leads and horizontal QRS axis can differentiate anterior myocardial infarction from aortic stenosis with high sensitivity and specificity.     

70岁以上健康老年人右胸及后壁导联心电图特点分析

目的研究70岁以上健康老年人右胸及后壁导联心电图特点。方法对212例70岁以上健康老年人右胸及后壁导联的P波、QRS波及ST段进行形态观察及测量分析。结果(1)右胸导联rS波形检出率为31.1%～58.1%;QS波形检出率为14.0%～23.3%;V4R导联(QS波除外)、V5R导联各波振幅低于V3R导联(P<0.05);(2)后壁V7～V9导联qR波形检出率为50.0%～87.7%;R波形检出率为7.1%～34.9%;与V7导联比较,V8、V9导联qR波形的出现率递增,R波形出现率及R波振幅均呈现递减(P<0.05);(3)ST段:V3R～V5R导联97.5%～98.9%位于等电位线;V7～V9导联97.2%～98.5%位于等电位线;极少数抬高者幅度<0.05mV,无ST段下降;(4)T波:V3R～V5R导联61.3%～79.2%为平坦,21.8%～25.8%为倒置;V7～V9导联45.1%～78.5%为平坦,20.0%～53.7%为直立。结论建立70岁以上老年人右胸及后壁导联心电图的诊断标准具有实际的临床意义。     

Electrocardiogram in pulmonary heart disease--clinical evaluation of right chest leads

A clinical study was made to evaluate the usefulness of electrocardiograms in right precordial leads (V3r or V4R) for the diagnosis of cardiac complications among patients with chronic pulmonary disease. Walsh and colleagues reported that the change of direction in the terminal vector of QRS loop in the vector cardiogram is useful for the evaluation of chronic pulmonary heart disease. They showed that the terminal vectors of QRS loops tend to deviate to the right and/or posterior direction in the early stage of chronic pulmonary heart disease. We utilized the electrocardiograms in the right precordial leads to detect the second R waves, which are thought to reflect the terminal vectors of QRS loops in the vectorcardiograms. When the electrocardiograms in the right precordial leads were compared, the second R waves in leads V3R or V4R were more frequently observed among patients with chronic pulmonary heart disease than those without. However, in the same two groups, the frequency of second R waves in leads V5R or V6R didn't differ. We conclude that the second R waves in leads V3R or V4R in a patient with chronic lung disease suggest the presence of chronic pulmonary heart disease as a complication.     

Analysis of the effects of the continuous electrode paste band on precordial leads of the electrocardiogram

OBJECTIVE - To determine if the application of a continuous electrode paste band on precordial leads results in alteration of the electrocardiographic tracing as compared with an adequate amount of electrode paste, and if the former condition does not cause uniform morphologies from V1 to V6. METHODS - The amplitude and morphology of the electrocardiographic waves on the precordial leads in electrocardiographic tracings, which were performed with standard (control group) or excessive (continuous band) application of the electrode paste, were compared. RESULTS - None of the 106 patients studied showed uniformity of the QRS morphology from V1 to V6. The eletrocardiographic alterations identified in the tracings performed with a continuous electrode paste band that showed statistical significance in relation to the control group were the following: inversion of the P wave in V1; inversion of the T wave in V1, V2, and V3; appearance of R' waves in V1 and V2; disappearance of S waves in V1; appearance of S waves in V5 and V6; alterations in the amplitude of almost all waves, in all leads. CONCLUSION - Application of a continuous electrode paste band in the precordial leads may cause significant alterations in the electrocardiographic tracing obtained.     

Absent right precordial R waves are associated with reduced left ventricular function and poor prognosis in patients with aortic stenosis

Right precordial Q waves can be present in patients with aortic stenosis as well as in those with anterior myocardial infarction. In order to evaluate the relationship of right precordial Q waves to left ventricular function and prognosis in patients with aortic stenosis, we studied 49 such patients with no history of myocardial infarction, by means of ECG, clinical history and echocardiography. 15 (31%) patients had Q waves in both V1 and V2 and 34 (69%) did not. There were no differences in age (77+/-9.0 years vs. 78+/-9.7), follow-up time (15+/-9.0 months vs. 18+/-10), gender (female:male 8:7 vs. 15:19), aortic valve gradient on Doppler (70.0+/-20 mmHg vs. 71+/-20) and left ventricular mass (360+/-118 g vs. 320+/-80) between the two groups (all P=NS). Left ventricular shortening fraction (22+/-9.0% vs. 28+/-8.5, P<0.05), ejection fraction (51+/-15% vs. 62+/-12, P<0.01) and circumferential fibre shortening (0.8+/-0.3 circ/s vs. 1.0+/-0.3, P<0.0s) were all significantly reduced in patients with right precordial Q waves compared to those without. During a mean follow-up of 1.5 years, 9 out of 15 (60%) patients with right precordial Q waves died compared with only 5 out of 34 (15%) patients with a normal QRS pattern died (P<0.01). In summary, a right precordial QS ECG pattern is present in nearly 1/3 patients with aortic stenosis and is associated with impaired left ventricular systolic function and adverse prognosis.     

Right precordial ST and QRS changes in the diagnosis of right ventricular infarction

Two groups of patients with anatomically proved acute myocardial infarction were compared in order to study specificity and sensitivity of the ECG criteria previously described in clinical and experimental right ventricular infarction ( RVI ). Group 1 included 21 patients with left inferior infarction and with a variable degree of right ventricular involvement; group 2 included nine patients with myocardial infarction confined to the left inferior wall. In both groups the presence of ST elevation (at least 0.05 mV) and the morphology of the QRS complex in V4R , V3R, and V1 were assessed in ECGs performed at the time of admission. Also, in order to evaluate the morphology of the ST segment and QRS complex in right precordial leads in normal subjects, an ECG with 12 standard and four right precordial leads ( V6R to V3R) was performed in 82 subjects (group 3) without clinical and ECG evidence of heart disease. Our data reveal that in normal subjects an rS pattern is always present in V3R and frequently (91%) in V4R . On the contrary, the presence of QS or QR complexes in both V4R and V3R are specific markers of right ventricular necrosis (specificity 100%; sensitivity 78%). The presence of injury and necrosis waves in V4R or V4R to V3R during inferior infarction is a useful diagnostic criterion in that it insures a highly specific diagnosis of acute RVI in the great majority (76 and 71%, respectively) of the cases with autopsy evidence of right ventricular involvement.     

Successful radiofrequency catheter ablation of epicardial left ventricular outflow tract tachycardia from the anterior interventricular coronary vein

We report a case of idiopathic left ventricular outflow tract (LVOT) tachycardia that was eliminated by a radiofrequency application from the anterior interventricular coronary vein (AIV). The ECG exhibited QRS complexes with an inferior axis and atypical left bundle branch block pattern with an early transition of the precordial R waves at V3. Several radiofrequency applications from the coronary cusps and endocardial LVOT were not effective. Radiofrequency applications in the AIV, where the activation preceded the onset of the QRS by 30 msec, successfully eliminated the tachycardia. The AIV may be an optional site for radiofrequency ablation of idiopathic epicardial LVOT tachycardia.