Wave In aVR Research Articles

ECG Response: December 24/31, 2013

HomeCirculationVol. 128, No. 25ECG Response: December 24/31, 2013 Free AccessResearch ArticlePDF/EPUBAboutView PDFView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissions ShareShare onFacebookTwitterLinked InMendeleyReddit Jump toFree AccessResearch ArticlePDF/EPUBECG Response: December 24/31, 2013 Originally published24 Dec 2013https://doi.org/10.1161/CIRCULATIONAHA.113.007191Circulation. 2013;128:2810A 64-year-old man presents to the emergency room with a history of 2 hours of substernal chest discomfort that radiates to his lower jaw and left arm. The discomfort is associated with severe diaphoresis. Physical examination demonstrates a blood pressure of 150/90 mm Hg, bibasilar rales, and an S4. Initial cardiac biomarkers are normal. However, based on the clinical presentation and the initial ECG (ECG A) the patient undergoes an urgent cardiac catheterization and an intervention is performed. On the following day a second ECG is obtained (ECG B).Download figureDownload PowerPointECG A: There is a regular rhythm at a rate of 120 bpm. There is a P wave before each QRS complex (+) with a stable PR interval (0.20 sec). The P waves are positive in leads I, II, aVF, and V4–V6. Hence this is a sinus tachycardia. The QRS complex duration is normal (0.08 sec). There are beat to beat changes in the axis (ie, a normal axis between 0° and +90°, ^; positive QRS complex in leads I and aVF) alternating with an extreme leftward axis between −30° and −90° (▴; positive QRS complex in leads I and negative QRS complex in leads II and aVF). There are 2 causes for an extreme left axis (ie, an inferior wall myocardial infarction in which there is a deep initial Q wave in leads II and aVF or a left anterior fascicular block in which the QRS complex in leads II and aVF has an rS morphology). This extreme leftward axis is a left anterior fascicular block. There is J point and ST segment elevation in leads V2–V6 (↓), consistent with an extensive ST segment elevation myocardial infarction of the anterior wall. The QT/QTc intervals are normal (280/400 ms). Also noted are beat to beat changes in the amplitude of the QRS complexes in leads V5–V6 (→), which is QRS or electric alternans. QRS or electric alternans is seen in several conditions including an acute ST elevation myocardial infarction, any rapid supraventricular tachycardia, decompensated heart failure, and a severe cardiomyopathy. In these situations the cause is beat to beat changes in calcium fluxes. QRS alternans is also seen in a large pericardial effusion or tamponade and the cause is shifting of the heart in a fluid filled pericardial sac. The beat to beat change in axis is possibly a manifestation of the QRS alternans, although it may also reflect an intermittent left anterior fascicular block resulting from the acute myocardial infarction.ECG B: The ECG obtained a day after the cardiac catheterization shows a regular rhythm at a rate of 64 bpm. There is a P wave before each QRS complex (+) with a stable PR interval (0.20 sec). The P wave is positive in leads I, II, aVF, and V4–V6, hence this is a normal sinus rhythm. The QRS complex duration is normal (0.08 sec), and there is an extreme left axis between −30° and −90° (positive QRS complex in lead I and negative QRS complex in leads II and aVF). This is a left anterior fascicular block which is now persistent. There is a QS complex in leads V1–V2 (↓), consistent with an anteroseptal myocardial infarction and T wave inversions in leads I, II, aVR (positive T wave in aVR is actually inverted), aVL, aVF, and V2–V6 (^). The T waves are symmetrically inverted, consistent with the recent ischemic event.Please go to the journal’s Facebook page for more ECG Challenges: http://goo.gl/cm4K7. Challenges are posted on Tuesdays and Responses on Wednesdays.FootnotesCorrespondence to Philip J. Podrid, MD, West Roxbury VA Hospital, Section of Cardiology, 1400 VFW Parkway, West Roxbury, MA 02132. E-mail [email protected] Previous Back to top Next FiguresReferencesRelatedDetails December 1, 2013Vol 128, Issue 25 Advertisement Article InformationMetrics © 2013 American Heart Association, Inc.https://doi.org/10.1161/CIRCULATIONAHA.113.007191PMID: 24366590 Originally publishedDecember 24, 2013 PDF download Advertisement SubjectsElectrocardiology (ECG)

Complete Absence of Precordial R Waves Due to Absence of Left‐Sided Pericardium

Poor R-wave progression (PRWP) in the precordial leads on random ECG is relatively frequent in the general population and includes a broad differential diagnosis. Here, we present for the first time a case of complete absence of precordial R waves associated with a prominent R wave in aVR due to the absence of the left-sided pericardium in a 44-year-old woman who experienced sudden cardiac death.

Right side or left side: an inconspicuous masquerade

Careful examination of the ECG in Fig. 1 shows inverted P waves in leads I, aVL and V2 to V6. Also notice the upright P waves in aVR and absence of R wave progression in the precordial leads. These are classic findings in dextrocardia. Hence the important physical examination finding in this patient would be better audibility of heart sounds on the right side of the precordium. Limb lead reversal causing ‘technical dextrocardia’ is a close differential diagnosis, but can be ruled out here as it would not explain the inverted P waves seen in V2 to V6.[1] Fig. 1 Standard 12-lead ECG Fig. 1 also shows a wide QRS complex with rSR’ pattern, resembling a right bundle branch block (RBBB), in the precordial leads. On close inspection, the wide S waves which are characteristically seen in the lateral leads in a RBBB are absent in this ECG. Hence the widened QRS complex in this ECG might be attributed to an intraventricular conduction delay. An ECG was deliberately repeated with the precordial leads kept on the right side of the chest and with reversal of leads aVR and aVL (Fig. 2). Now the ECG shows a complete RBBB with first-degree AV block. The wide S waves in the lateral leads and normalisation of P wave morphology are easily noticeable. The patient was eventually found to have episodes of ventricular tachycardia which caused her palpitations. Fig. 2 ECG done after reversal of limb leads and with chest leads kept on the right side of the precordium This case highlights how RBBB in a patient with dextrocardia can masquerade as an intraventricular conduction delay unless an ECG is taken with right-sided precordial leads.

Takotsubo cardiomyopathy resembling acute high lateral myocardial infarction

A 65-year-old female patient admitted to the emergency department was diagnosed with acute high lateral myocardial infarction, but later Takotsubo cardiomyopathy (TC) was discovered. She had squeezing chest pain that started shortly after an emotional stress. The electrocardiogram revealed a loss of R wave voltage in leads V1 to V4 and an ST-segment elevation in I and aVL. After an urgent coronary angiography and ventriculography, TC was considered, and supportive anti-ischemic treatment was started. The severe left ventricular systolic dysfunction improved and normalized during the follow-up. She was discharged without any complications. TC is a new entity of acute cardiac events, and patients usually recover completely without sequelae with proper diagnosis and management. An exact diagnosis may also prevent an inappropriate application in the setting of recurrences.

Posterior fascicular block obscuring the right bundle branch block pattern

☆ Competing interest: none ☆☆ No funding ⁎ Corresponding author at: Division of Cardiology, Ospedale Civile, 44042 Cento (FE) It E-mail address: alboni.cardiologia@gmail.com (P. Alboni). Fig. 1. Patient A. Sinus bradycardia, first degree atrioventricula block, right bundle branch b wave in V6 are absent. Patient B. Atrial flutter with variable, mainly 4:1, atrioventricular condu wave in aVR is absent and the S wave in V6 is very small.

Wide Complex Tachycardia in a Pediatric Diphenhydramine Overdose Treated With Sodium Bicarbonate

Diphenhydramine is an antihistamine commonly implicated in overdose. It has many pharmacologic effects, including sodium channel blockade. Overdoses in toddlers causing QRS prolongation are only rarely reported and never with effective use of sodium bicarbonate. We report a diphenhydramine overdose in a toddler with multiple markers of sodium channel blockade effectively treated with sodium bicarbonate. A 13-month-old infant girl was brought in by the emergency medical service for a witnessed tonic-clonic seizure. Two hours previously, the child had been found with an open bottle of 25-mg diphenhydramine tablets, 24 of which were missing. Midazolam was administered with seizure resolution. Examination revealed 4-mm reactive pupils; nystagmus; warm, dry, flushed skin; and altered mental status. Initial electrocardiograms revealed sinus tachycardia at a rate of 180 beats per minute, a prolonged QRS of 130 milliseconds (from a baseline of 65 milliseconds), and a positive terminal R wave in aVR, which later resolved after sodium bicarbonate treatment. The patient was discharged home the following day with no sequelae. Diphenhydramine toxicity is a common poisoning in children. Toxicity typically presents with signs and symptoms of the anticholinergic toxidrome. Diphenhydramine also has sodium channel-blocking properties, and this can be shown in the form of prolonged QRS and a terminal R wave in aVR. QRS prolongation and aVR abnormalities from diphenhydramine ingestion in a toddler have been reported, but effective use of sodium bicarbonate has not. Electrocardiographic finding consistent with sodium channel blockade should be recognized as a complication of pediatric diphenhydramine overdose, and they seem responsive to hypertonic sodium bicarbonate.

Acute myocardial infarction in a patient of dextrocardia and situs inversus totatis—when right is not right

Diagnosis of myocardial infarction in patients with dextrocardia and situs inversus is considerably difficult. The clinical diagnosis and electrocardiography (ECG) recognition in this setting poses significant challenges, as the clinical signs may be misleading and the ECG changes may simply be interpreted to be due to improper lead placement. In this case report we report one such case of acute myocardial infarction in a patient of situs inversus totalis. A deviated apex beat and heart sounds coupled with right axis deviation of P wave and QRS complexes in lead I, and positive R wave in aVR lead to the diagnosis of dextrocardia. Elevated ST segment in Vl and right-sided leads indicated acute myocardial infarction which was later confirmed by raised creatine phosphokinase-MB (CPK-MB) levels, and transthoracic echocardiography.

Specificity of the wide QRS complex tachycardia algorithms in recipients of cardiac resynchronization therapy

BackgroundWe assessed the specificity of wide QRS complex tachycardia (WCT) differentiating algorithms in patients with preexistent left bundle branch block (LBBB) and heart failure. MethodsThree hundred fourteen patients with resynchronization devices were retrospectively screened. electrocardiograms with supraventricular LBBB rhythm were used as a surrogate for supraventricular tachycardia QRS morphology. The Pava lead II criterion, ventricular activation velocity ratio (Vi/Vt) ratio in V2, Vereckei aVR, Brugada, Griffith, and Bayesian algorithms were investigated. ResultsThe WCT algorithms had a lower specificity (33%-69%) in patients with LBBB than in general WCT populations. The Pava lead II criterion and Brugada algorithm had higher specificity than other algorithms (P < .05). Several of the single criteria (absence of an RS complex in V1 through V6, initial R wave in aVR, Vi/Vt < 1 in V2) had specificities of 92% to 99%. ConclusionsIn patients with heart failure and LBBB, an electrocardiographic diagnosis of ventricular tachycardia should be based on selected, specific criteria rather than on WCT algorithms.

Effect of Limb Lead Electrodes Location on ECG and Localization of Idiopathic Outflow Tract Tachycardia: A Prospective Study

Different kinds of the surface ECG limb electrode positions may affect the limb lead vector and therefore the accuracy of the 12-lead ECG in localization of outflow tract ventricular tachycardia (OTVT). This study was intended to evaluate and compare the accuracy of the standard and the modified 12-lead ECG for localization of OTVT using the current published criteria. Twenty consecutive patients (10 men, mean age, 51.6 ± 13.4 years) with OT-VT were included. A standard ECG with the distal placement of the limb lead electrodes and a modified ECG with the limb electrodes placed on the torso were recorded during the OT-VT and were used for localization by 2 electrophysiologists who were blinded to the successful ablation site to compare the accuracy of the 2 ECGs. The R wave amplitude during OT-VT in lead I of the standard 12-lead ECG was significantly higher compared to the modified surface ECG (0.225 ± 0.145 mV vs 0.139 ± 0.111 mV, P = 0.032). The S wave in aVR during OT-VT was significantly more negative compared to the modified surface ECG (-0.682 ± 0.182 mV vs -0.527 ± 0.228 mV, P = 0.017). The rate of accurate localization of the successful ablation sites in the anterior versus posterior outflow tract by the 2 observers using standard ECG (70% and 80%) were higher compared to modified ECG (50% and 60%, P = 0.042). The R wave amplitude in lead I and the depth of the S wave amplitude in lead aVR of the standard surface ECG during OT-VT is significantly larger compared to the modified surface ECG. As the QRS morphology of the OT-VT is usually the first clue to the possible site of successful ablation, the standard 12-lead ECG should be used for more accurate localization of the origin of the OT-VT.

Clinical, Electrocardiographic, and Laboratory Findings in Children With Amitriptyline Intoxication

Amitriptyline is one of the major tricyclic antidepressants, and the data on amitriptyline poisoning in children are limited. To present our experiences with amitriptyline poisoning in children, particularly with regard to its effects on electrocardiogram (ECG) and relation with clinical status. Clinical, laboratory, and electrocardiographic findings in 52 children admitted with amitriptyline poisoning were reviewed. Patients were divided into 2 groups according to age, as 6 years or younger (group A) and older than 6 years (group B). Mean age was 4.6 +/- 3.0 years. Thirty-one patients were male, and 41 were 6 years or younger. Ingested amitriptyline dose was known in 23 patients (range, 2.3 mg/kg-27 mg/kg). The most frequent findings were lethargy (76.9%), sinus tachycardia (57.7%), and coma (48.1%). Four patients had a history of convulsion. The most common laboratory abnormalities were hyponatremia (26.9%) and leukocytosis (25%). Elevated transaminase levels were observed in 4 patients. In ECG, 11 (22.4%) patients had QTc prolongation and in 4 (8.2%) of them, it was significant. In 4 patients (8.2%), the QRS duration was 100 ms or longer and in 15 patients, the R wave in aVR was 3 mm or longer. The frequencies of clinical, laboratory, and electrocardiographic findings were similar between the 2 age groups (P > 0.05). No clinically apparent arrhythmias were observed. The positive predictive value of a widened QRS was 100% in terms of coma. None of the patients with an R wave in aVR of less than 3 mm developed convulsion; thus, the negative predictive value of an R wave in aVR of 3 mm or longer was 100% in terms of convulsion. Amitriptyline poisoning may result in severe toxicity. Frequencies of clinical, laboratory, and ECG findings were similar in the 2 age groups. Amitriptyline overdose results in some ECG changes that can possibly help to predict the results of poisoning. Absence of an R wave in aVR of 3 mm or longer predicts seizures with a high negative predictive value, and a QRS duration of 100 or longer ms predicts coma with a high positive predictive value.

Markers of Coronary Sinus Accessory Pathways in Pediatrics

Coronary sinus accessory pathways (CSAPs), atrioventricular connections formed by the coronary sinus myocardial coat, have been described in adult patients, but not systematically described in pediatric patients. Patients who underwent CSAP ablation were compared to patients with right posteroseptal (RPS) pathway ablation (control group) from November 2004 to June 2007. Retrospective reviews of preablation 12-lead electrocardiogram (EKG), fluoroscopic, and intracardiac electrogram data were then performed to identify electrophysiologic markers of CSAP. A total of 23 patients were identified: 13 with CSAP and 10 with RPS pathways. Preablation EKGs demonstrated preexcitation in 8/10 (80%) patients with RPS pathways versus 9/13 (69%) patients with CSAP (P = 0.66). Preexcitation with a negative delta wave in lead II was seen in 5/9 (56%) patients with CSAP versus 0/8 in RPS (P = 0.029), and preexcitation with a positive delta wave in augmented vector right (aVR) was seen in 9/9 (100%) patients with CSAP versus 3/8 (37.5%) with RPS (P = 0.009). Accessory pathway (AP) potentials were seen on the coronary sinus (CS) catheter in 6/13 (46%) of CSAP and in 0 RPS ablations (P = 0.019). Recurrence of tachycardia occurred in 5/13 (38%) of patients with CSAP and 1/10 (10%) of patients with RPS pathways (P = 0.18). CSAPs should be considered when preablation EKG demonstrates preexcitation with a negative delta wave in lead II and a positive delta wave in aVR, and if an AP potential is seen on the CS catheter. Recurrence of tachycardia postablation or the need for multiple ablations should raise suspicion for a CSAP.

Utility of 12‐Lead Electrocardiogram for Differentiating Paroxysmal Supraventricular Tachycardias in Dogs

The 12-lead surface ECG is validated for differentiating supraventricular tachycardias (SVT) in humans. Despite the description of SVT in veterinary medicine, no studies have analyzed the electrocardiographic features of this type of arrhythmias in dogs. To describe the specific electrocardiographic criteria used to differentiate the most common SVT in dogs. Twenty-three dogs examined at Clinica Veterinaria Malpensa for SVT with the mechanism documented by electrophysiologic studies (EPS). Twelve-lead electrocardiographic variables obtained from 14 dogs with orthodromic atrioventricular reciprocating tachycardia (OAVRT) and 9 dogs with focal atrial tachycardia (FAT) were compared. Dogs with FAT had faster heart rates (278 +/- 62 versus 229 +/- 42 bpm; P= .049) and less QRS alternans (33 versus 86%; P= .022). P waves appeared during tachycardia in 22 dogs, with a superior axis in 100% of OAVRT and 22% of FAT (P < .001). OAVRT was characterized by a shorter RP interval (85.0 +/- 16.8 versus 157.1 +/- 37.3 ms; P < .001) and smaller RP/PR ratio (0.60 +/- 0.18 versus 1.45 +/- 0.52; P < .001). Repolarization anomalies were present in 64% of OAVRT and no FAT (P < .001). Multivariate analysis identified QRS alternans and a positive P wave in aVR during tachycardia as independent predictors of arrhythmia type. Electrocardiographic criteria used in people for differentiating SVT can also be applied in dogs.

The Prognostic Value of T Wave Amplitude in Lead aVR in Males

Since there is an uncertainty regarding which of the 12 leads provides the most information, we investigated the association between repolarization phenomenon in all of the 12 leads and cardiovascular (CV) mortality. Retrospective cohort study was performed at Palo Alto Veterans Affairs Medical Center, Palo Alto, California, which included 24,270 consecutive male veterans with ECGs obtained for clinical reasons from 1987 to 2000. Analysis of computerized 12-lead resting ECGs was performed of all subjects excluding inpatients, patients with atrial fibrillation, WPW, QRS duration > 120 ms, and paced rhythms. Average follow-up was 7.5 years during which time there were 1859 CV deaths. While ST segment measurements in aVR were univariately predictive of CV death, T wave amplitude superseded them in multivariate survival analysis. In addition, T wave amplitude in aVR outperformed repolarization measurements in all other leads as well as other ECG criteria (Q waves, damage scores, LVH) for predicting CV mortality. As T wave amplitude became less negative in aVR, there was a progressive increase in relative risk (RR). When the T waves in aVR had a positive deflection (i.e., upward pointing) the RR for CV death was 5.0. T wave amplitude in lead aVR is a powerful prognostic marker for estimating risk of CV death. Upward pointing T waves (a simple visual criterion) was prevalent (7.3% of a clinical population) and was associated with an annual CV mortality of 3.4% and a risk of five times.

Abstract 1825: Abnormal ECG Markers suggest that Accentuated Intracardiac Conduction Delay is The Common and Distinguishing Feature of Patients with Spontaneous Type 1 ECG or SCN5A Mutation in Brugadas Syndrome

The conclusive diagnosis of Brugada Syndrome (BrS) is established in patients (pts) with spontaneous type 1 ECG or in carriers of a loss of function SCN5A mutation. We carried out a systematic analysis of ECG recordings in BrS pts to test the hypothesis that the presence of intraventricular (Intra-Ven) and atrioventricular (A-Ven) conduction delay is the distinguishing common feature of pts with SCN5A mutations (Mut+) and in pts with a spontaneous type 1 ECG pattern (spont-ECG). We assessed the following 5 ECG parameters: late potentials (quantified as RMS at 40 Hz), aVR sign (relative size of the R and q waves in aVR), QRS complex fragmentation (defined as an additional R′ or notching of the of S wave), PQ and QRS duration. We studied 200 consecutive BrS pts to define whether the prevalence of ECG markers correlate with 1) the presence of a SCN5A mutation (Mut+) or 2) the presence of a spontaneous type 1 pattern ECG (spont-ECG). Results are summarized in the table . Interestingly, Mut+ not only presented prolonged PQ (p&lt;0.003 vs Mut÷) as previously reported but more significantly they showed the presence of abnormal markers of intraventricular conduction (QRS duration, aVR sign and late potentials). Similarly, also the presence of a spont-ECG was associated with prolonged PQ and QRS intervals and with late potentials. Based on our ECG analysis we propose that Brugada syndrome is a disease characterized by impairment of A-Ven and Intra-Ven conduction, the presence of a mutation in the SCN5A gene and, the presence of a spontaneous type 1 ECG identify patients with accentuated conduction defects. These findings suggest that the presence of interventricular conduction delay is a landmark of BrS and should be considered as diagnostic markers in BrS.

Normalization of Negative T Waves in the Chronic Stage of Q Wave Anterior Myocardial Infarction as a Predictor of Myocardial Viability

We investigated whether spontaneous normalization of negative T waves (TWN) on infarct-related ECG leads (IRLs) in the chronic phase of Q wave anterior myocardial infarction (MI) could be a predictor of residual viability in infarct areas. We prospectively studied 35 patients (age 60 ± 8.6 years) in the chronic phase of Q wave anterior MI. Spontaneous TWN (group A, n = 23) were defined as negative T waves that became upright (≧0.15 mV) in ≧2 IRLs. The presence of negative T waves (group B, n = 12) was defined as symmetric or biphasic negative T wave of ≧0.15 mV. All patients underwent same-day rest ²⁰¹Tl-stress ^99mTc sestamibi dual-isotope myocardial perfusion SPECT and 24-hour ²⁰¹Tl reinjection imaging for ischemia and viability analysis. On scintigraphic examination, ischemic or viable myocardial segments were found in 18 patients (78%) with TWN and 4 patients (33%) of group B (p = 0.013). The use of TWN as a parameter had a marked influence on the sensitivity (82%), specificity (62%), positive (78%) and negative (67%) predictive values and accuracy (74%) of the diagnosis of viable myocardium. If we add the criterion of positive T waves in aVR with negative T waves to our criteria, we found that sensitivity (90%), positive (80%) and negative (80%) predictive values and accuracy (80%) increased. The results of our study suggest that analysis of TWN on IRLs is an accurate marker of residual viability and/or persistent peri-infarct ischemia in patients in the chronic stage of Q wave anterior MI, and therefore optimizes the diagnostic and therapeutic strategies after MI.

Paraseptal Accessory Pathway in Wolff-Parkinson- White-Syndrom: Ablation from the Right, from the Left or within the Coronary Sinus/Middle Cardiac Vein?

In 1999 the consensus statement "living anatomy of the atrioventricular junctions" was published. With that new nomenclature the former posteroseptal accessory pathway (APs) are termed paraseptal APs. The aim of this study was to identify ECG features of manifest APs located in this complex paraseptal space. ECG characteristics of all patients who underwent radiofrequency ablation of an AP during a 3 year period were analyzed. Of the 239 patients with one or more APs, 30 patients had a paraseptal AP with preexcitation. Compared to APs within the coronary sinus (CS) or the middle cardiac vein (MCV) the right sided paraseptal APs significantly more often showed an isoelectric delta wave in lead II and/or a negative delta wave in aVR. The left sided paraseptal APs presented a negative delta wave in II significantly more often compared to the right sided APs. According to the site of radiofrequency ablation, paraseptal APs are classified into 4 subgroups: paraseptal right, paraseptal left, inside the CS or inside the MCV. Subtle differences in preexcitation patterns of the delta wave as well as of the QRS complex exist. However, the definitive localization of APs remains reserved to the periinterventional intracardiac electrogram analysis.

Diagnosis

Diagnosis

Hereditary bundle branch defect: Right bundle branch blocks of different causes have different morphologic characteristics

Hereditary bundle branch defect is an autosomal dominant genetic disease that, in a large Lebanese family, was mapped to the long arm of chromosome 19. Affected individuals have various combinations of conduction defects such as right bundle branch block, left or right QRS frontal-axis deviation, or atrioventricular blocks. We now further characterize this disease with the presentation of a two-decade follow-up and analysis of electrocardiographic features and mutation-carrier status. The conduction block may be overt in the first year of life, and among affected individuals, there is a worsening of the conduction block in 5% to 15% of cases, leading to complete atrioventricular block and possibly to sudden death. A group of individuals had QRS anomalies in right precordial leads such as rsr′s′, rss′, or rSr′, which may account for partial right bundle branch blocks. In this group, which we referred to as having an “r′ pattern,” 53% were actually mutation carriers, and 19% evolved toward a complete fascicular block. By contrast, mutation carriers with a normal electrocardiogram remained normal. The QRS morphologic appearance in the right precordial leads of affected individuals and r′ pattern mutation carriers is notable for the absence or weakness of negative forces resulting in a rsR′ or rR′ morphology. In addition, an r′ pattern is highly suggestive of a mutation carrier status in the presence of a broad r wave in aVR and s in V 6 or a frontal-axis deviation. Finally, mutation carriers demonstrate a conduction block significantly more often in males than females (75% and 50%, respectively). This incomplete penetrance and slow evolution suggest that the actual prevalence of hereditary bundle branch defect is very much underestimated. (Am Heart J 1997;133:249-56.)

Prominent anterior QRS forces: Clinical, electrocardiographic and prospective study

Recent data suggest that the prominent anterior QRS forces (R greater than or equal to S in V1 and/or V2 leads), in the absence of posterior myocardial infarction, right ventricular hypertrophy, or WPW syndrome, are related to an intraventricular conduction disturbance, at times rate-dependent. We followed 240 subjects with prominent anterior QRS forces and without the above mentioned diseases (study group), (mean age: 44.6 +/- 16 years, mean follow-up: 8 +/- 2 years) and 240 subjects without the anterior displacement (control group), (mean age: 44.4 +/- 14 years, mean follow-up: 7.9 +/- 1.9 years). The age distribution, sex, prevalence of organic heart disease, and follow-up period did not show significant differences between the two groups. QRS duration, prevalence of left ventricular hypertrophy pattern, S1 S2 S3 morphology, terminal r wave in AVR and s wave in V6 were similar in the two groups. During the follow-up period the incidence of right and left bundle branch block and fascicular block was very similar in the two groups of patients. These data suggest that prominent anterior QRS forces do not appear to be related to an initial involvement of the main bundle branches and fascicles and do not increase the likelihood of appearance of an intraventricular block of more advanced degree. The clinical, ECG and prospective data are not helpful in localizing either the ventricle or the area of the ventricle affected by conduction disturbance responsible for the anterior displacement. Our data suggest that the prominent anterior QRS forces express a normal variant of ventricular depolarization and that this finding does not have, per se, any unfavourable clinical implication.

Case of left atrial rhythm associated with mirror-image dextrocardia

A girl of thirteen years was admitted to Iwate Medical University Hospital on December 22th, 1956, complaining of palpitation by physical exertion since childhood. She had a splendid physique and was well-nourished, and didn't have any acquired diseases at that time. But her heart had a shape of dextrocardia on chest x-ray film, and it had been recognized on physical and x-ray examinations that she had heterotaxia of abdominal organon. Marked systolic murmur was heard on the right sternal line in the IIIrd intercostal space. The right and left heart catheterization had revealed VSD and ASD. The right and left heart catheterization and the cineangiocardiography suggested strongly mirror image dextrocardia. Nevertheless in ECG, P waves in I, aVL and left precordial leads were positive with a P-R interval of 0.19 second, and P waves in aVR, V4R, V5R, and V6R were negative. So they didn't coincide with the ordinary ECG-criteria of mirror image dextrocardia. But mirror image dextrocardia, as well as VSD and foramen ovale, were made sure by operation. Namely the P wave pattern above mentioned was proved to represent left atrial rhythm. Also "dome and dart" type P waves were seen m V2. So this left atrial rhythm was fit for the lst type, according to the classification of M. MIRROWSKI. After operation, pacemaker wandering between sinus node and left atrium was seen without artificial procedures. In sinus rhythm, P waves in I, aVL and left precodial leads were negative with a P-R interval of 0.20 second and P waves in aVR, V4R, V5R and V6R were positive. Compression on eyeballs or carotid sinus failed to change the position of pacemaker. But posture change from supine to erect position converted left atrial rhythm to sinus rhythm.