Intraventricular Conduction Disturbances Research Articles

症例 心室内伝導障害を伴った小児特発性sick sinus syndoromeの1例

症例 心室内伝導障害を伴った小児特発性sick sinus syndoromeの1例

Left bundle branch block, atrioventricular block, torsade de pointes and long QT syndrome: Is this too much for a rare cardiomyopathy?

Left ventricular noncompaction (LVNC) is now recognized as a distinct form of cardiomyopathy with a clinical presentation and natural history of its own. Common manifestations of LVNC include heart failure, ventricular arrhythmias and embolic events, but serious atrioventricular conduction disturbances are rarely reported in the literature. The authors describe the case of a 40-year-old woman who went to the emergency department due to syncope. The ECG revealed left bundle branch block (LBBB) and 2:1 atrioventricular block (AVB) and the patient was admitted for pacemaker implantation. During hospitalization she developed torsade de pointes and complete AVB with increased QTc. The echocardiogram showed images compatible with LVNC. This case provides additional evidence that LVNC may be complicated by 2:1 (or complete) AVB, intraventricular conduction disturbances (LBBB) and repolarization abnormalities (long QT). This combination of electrocardiographic changes has rarely been reported in the literature. We describe a series of affected patients, focusing on electrocardiographic characteristics.

Bloqueio completo de ramo esquerdo, bloqueio auriculoventricular, torsade de pointes e QT longo: será demasiado para uma rara miocardiopatia?

Left ventricular noncompaction (LVNC) is now recognized as a distinct form of cardiomyopathy with a clinical presentation and natural history of its own. Common manifestations of LVNC include heart failure, ventricular arrhythmias and embolic events, but serious atrioventricular conduction disturbances are rarely reported in the literature. The authors describe the case of a 40-year-old woman who went to the emergency department due to syncope. The ECG revealed left bundle branch block (LBBB) and 2:1 atrioventricular block (AVB) and the patient was admitted for pacemaker implantation. During hospitalization she developed torsade de pointes and complete AVB with increased QTc. The echocardiogram showed images compatible with LVNC. This case provides additional evidence that LVNC may be complicated by 2:1 (or complete) AVB, intraventricular conduction disturbances (LBBB) and repolarization abnormalities (long QT). This combination of electrocardiographic changes has rarely been reported in the literature. We describe a series of affected patients, focusing on electrocardiographic characteristics.

New Clinical and Electrocardiographic Classification in Patients with Idiopathic Ventricular Fibrillation

The presence of early repolarization (ER) recently has been considered as a prognostic marker for sudden cardiac death in patients with idiopathic ventricular fibrillation (IVF), but there are certain numbers of IVF patients lacking ER. We aimed to clarify the clinical and electrocardiographic characteristics of the patients with IVF in the presence and absence of ER. We studied 64 consecutive IVF patients from the Japan Idiopathic Ventricular Fibrillation Study (J-IVFS) registry, which subjected with at least one episode of documented VF in the absence of structural heart diseases and excluding Brugada syndrome. We assessed clinical and electrophysiological characteristics in the IVF patients with and without ER. ER was defined as J-point elevation of >0.1 mV in either inferior or lateral leads. Twelve-lead electrocardiogram (ECG) demonstrated 24 (38%) of 64 patients with ER (ER[+] group) and the remaining 40 (62%) patients without ER (ER[-] group ). ER[+] group had a male predominance (92% for males) and ER[-] group revealed nearly equal distribution in both sexes. While no patients in ER[+] group showed intraventricular conduction disturbance (CD) with abnormal axis deviation and/or bundle branch block in ECG, 9 in ER[-] group had signs of CD (ER[-]/CD[+] subgroup). ER[-]/CD[+] subgroup had prolonged P-R interval and QRS duration compared to other patient groups. We found 3 distinct ECG patterns in IVF patients. In addition to the presence and absence of ER, there is a subgroup without ER demonstrating intraventricular CD, which represents a distinct clinical entity of IVF.

Noninvasive Electrocardiographic Mapping to Improve Patient Selection for Cardiac Resynchronization Therapy: Beyond QRS Duration and Left Bundle Branch Block Morphology

This study sought to investigate whether noninvasive electrocardiographic activation mapping is a useful method for predicting response to cardiac resynchronization therapy (CRT). One third of the patients appear not to respond to CRT when they are selected according to QRS duration. We performed electrocardiographic activation mapping in 33 consecutive CRT candidates (QRS duration≥120 ms). In 18 patients, the 12-lead electrocardiographic morphology was left bundle branch block (LBBB), and in 15, it was nonspecific intraventricular conduction disturbance (NICD). Three indexes of electrical dyssynchrony were derived from intrinsic maps: right and left ventricular total activation times and ventricular electrical uncoupling (VEU) (difference between the left ventricular [LV] and right ventricular mean activation times). We assessed the ability of these parameters to predict response, measured using a clinical composite score, after 6 months of CRT. Electrocardiographic maps revealed homogeneous patterns of activation and consistently greater VEU and LV total activation time (LVTAT) in patients with LBBB compared with heterogeneous activation sequences and shorter VEU and LVTAT in NICD patients (VEU: 75 ± 12 ms vs. 40 ± 22 ms; p< 0.001; LVTAT: 115 ± 21 ms vs. 91 ± 34 ms; p= 0.03). LBBB and NICD patients had similar right ventricular total activation times (62 ± 30 ms vs. 58 ± 26 ms; p= 0.7). The area under the receiver-operating characteristic curve indicated that VEU (area under the curve [AUC]:0.88) was significantly superior to QRS duration (AUC: 0.73) and LVTAT (AUC: 0.72) for predicting CRT response (p<0.05). With a 50-ms cutoff value, VEU identified CRT responders with 90% sensitivity and 82% specificity whether LBBB was present or not. Ventricular electrical uncoupling measured by electrocardiographic mapping predicted clinical CRT response better than QRS duration or the presence of LBBB.

Rate-Dependent Bundle Branch Block: Not Only Phase 3 Exists

Rate-dependent bundle branch blocks are often related with increased heart rate(tachycardia-dependent or phase-3 bundle branch block). Less often, they arecaused by heart rate reduction (bradycardia-dependent or phase-4 bundle branchblock). Phase-3 block is the most common type of paroxysmal intraventricularconduction disturbances documented in several publications. However, few articlesdescribe phase-4 bundle branch block, and both mechanisms rarely coexist in thesame patient. We report the case of a patient admitted with acute myocardialinfarction, presenting with both tachycardia- and bradycardia-dependentparoxysmal intraventricular conduction disturbances.

Body Surface Electrocardiographic Mapping for Non-invasive Identification of Arrhythmic Sources.

The authors describe a novel three-dimensional, 252-lead electrocardiography (ECG) and computed tomography (CT)-based non-invasive cardiac imaging and mapping modality. This technique images potentials, electrograms and activation sequences (isochrones) on the epicardial surface of the heart. This tool has been investigated in the normal cardiac electrophysiology and various tachyarrhythmic, conduction and anomalous depo-repolarisation disorders. The clinical application of this system includes a wide range of electrical disorders like atrial arrhythmias (premature atrial beat, atrial tachycardia, atrial fibrillation), ventricular arrhythmias (premature ventricular beat, ventricular tachycardia) and ventricular pre-excitation (Wolff-Parkinson-White syndrome). In addition, the system has been used in exploring abnormalities of the His-Purkinje conduction like the bundle branch block and intraventricular conduction disturbance and thereby useful in electrically treating the associated heart failure (cardiac resynchronisation). It has a potential role in furthering our understanding of abnormalities of ventricular action potential (depolarisation [Brugada syndrome and repolarisation], long QT and early repolarisation syndromes) and in evaluating the impact of drugs on His-Purkinje conduction and cardiac action potential.

PROGNOSTIC EFFECT OF BLOCKADE OF THE RIGHT BUNDLE BRANCH BLOCK PATIENTS WITH ACUTE MYOCARDIAL INFARCTION

The study analyzes the influence on the prognosis of blockade of the right bundle branch block in patients with acute myocardial infarction. Score the prognostic value of blockade of the right bundle branch block was carried out in comparison with a group of patients without intraventricular conduction disturbances, and a group of patients with left bundle branch block. Established negative prognostic effect of blockade of the right bundle branch block in patients with acute myocardial infarction, and this negative effect was maintained after 30 days a year, 3 years.

Abstract 9473: Prognostic Significance of Temporal Increase in QRS Duration and Morphological Development of QRS Complex

Background: QRS duration and morphology provide an opportunity to derive useful prognostic information. But, prognostic value of temporal increase in QRS duration in relation to the morphological development is yet to be determined. Methods: From among a database containing 359,737 ECGs, digital analysis of 12-lead ECG was performed to select patients whose QRS duration increased from &lt;110 ms to ≥120 ms over time. The long-term prognosis was assessed according to QRS morphology. Hospitalization for heart failure was the primary end point, and the cardiovascular composite events of hospitalization for heart failure, device implantation, or cardiovascular death were the secondary end point. Results: We enrolled 143 patients (100 males; mean age, 58.9±11.1 years). During follow-up (mean, 12.0±5.3 years), QRS duration increased by 46.4±13.8 ms (49.6%), resulting in the development of right bundle branch block (RBBB) in 99 (69.2%) patients and non-RBBB (i.e., left bundle branch block,RBBB with left anterior hemiblock, or intraventricular conduction disturbance) in 44 (30.8%) patients. During a mean follow-up of 16.6±5.3 years, 44(30.3%),15(10.3%), and 6(4.1%) patients resulted in heart failure hospitalization,device implantation, and cardiovascular death, respectively. Cox proportional -hazards model showed that 1) the temporal increment of QRS duration was significantly associated with the primary end point (HR 1.98; 95% CI 1.05-3.80; P=0.04 for QRS duration ≥4 ms/year versus &lt;4 ms/year) and the secondary end point (HR 2.79;95% CI 1.55-5.00; P=0.0001 for QRS duration ≥5 ms/year versus &lt;5 ms/year),2) QRS morphology was significantly associated with the primary end point (HR 3.02;95% CI 1.59-5.73; P=0.0001 for non-RBBB versus RBBB) and the secondary end point (HR 2.82; 95% CI 1.57-3.09; P=0.001 for non-RBBB versus RBBB), and 3) the temporal increment of QRS duration and the QRS morphology of non-RBBB potentiated each other, leading to the higher primary end point rate (HR 7.73; 95% CI 2.90-22.74;P&lt;0.0001) and the higher secondary end point rate (HR 8.25; 95% CI 3.39-19.85; P&lt;0.0001). Conclusion: Newly developed wide QRS complex excluding RBBB played a significant role in heart failure hospitalization and cardiovascular events.

Loss of Function of hNa v 1.5 by a ZASP1 Mutation Associated With Intraventricular Conduction Disturbances in Left Ventricular Noncompaction

Background— Defects of cytoarchitectural proteins can cause left ventricular noncompaction, which is often associated with conduction system diseases. We have previously identified a p.D117N mutation in the LIM domain-binding protein 3–encoding Z-band alternatively spliced PDZ motif gene (ZASP) in a patient with left ventricular noncompaction and conduction disturbances. We sought to investigate the role of p.D117N mutation in the LBD3 NM_001080114.1 isoform (ZASP1-D117N) for the regulation of cardiac sodium channel (Na v 1.5) that plays an important role in the cardiac conduction system. Methods and Results— Effects of ZASP1-wild-type and ZASP1-D117N on Na v 1.5 were studied in human embryonic kidney-293 cells and neonatal rat cardiomyocytes. Patch-clamp study demonstrated that ZASP1-D117N significantly attenuated I Na by 27% in human embryonic kidney-293 cells and by 32% in neonatal rat cardiomyocytes. In addition, ZASP1-D117N rightward shifted the voltage-dependent activation and inactivation in both systems. In silico simulation using Luo-Rudy phase 1 model demonstrated that altered Na v 1.5 function can reduce cardiac conduction velocity by 28% compared with control. Pull-down assays showed that both wild-type and ZASP1-D117N can complex with Na v 1.5 and telethonin/T-Cap, which required intact PDZ domains. Immunohistochemical staining in neonatal rat cardiomyocytes demonstrates that ZASP1-D117N did not significantly disturb the Z-line structure. Disruption of cytoskeletal networks with 5-iodonaphthalene-1-sulfonyl homopiperazine and cytochalasin D abolished the effects of ZASP1-D117N on Na v 1.5. Conclusions— ZASP1 can form protein complex with telethonin/T-Cap and Na v 1.5. The left ventricular noncompaction-specific ZASP1 mutation can cause loss of function of Na v 1.5, without significant alteration of the cytoskeletal protein complex. Our study suggests that electric remodeling can occur in left ventricular noncompaction subject because of a direct effect of mutant ZASP on Na v 1.5.

Device therapy in Chagas disease heart failure

Chagas disease is the principal cause of chronic heart failure in areas where the disease is endemic. The medical treatment is the same recommended for non-Chagas disease patients. There is no evidence-based medicine support for device therapy in Chagas disease heart failure. Cardiac resynchronization therapy is recommended for Chagas disease heart failure patients with intraventricular conduction disturbances, mainly for those with left bundle branch block, and in advanced congestive heart failure refractory to targeted medical treatment, although this therapy is still polemic in Chagas disease heart failure. Implantable cardioverter–defibrillator (ICD) therapy is indicated to Chagas disease patients with left ventricular ejection fraction <30% for primary prevention of sudden cardiac death. ICD therapy is offered to patients for secondary prevention of sudden cardiac death. Patients with moderate left ventricular dysfunction and inducible arrhythmia at electrophysiological testing should receive ICD therapy.

Cardiac dysfunction in pediatric patients on renal replacement therapy

Dear Editor, We read with great interest the article by Malatesta-Muncher et al. entitled “Early cardiac dysfunction in pediatric patients on maintenance dialysis and post kidney transplant”, where the authors discussed the problem of “cardiorenal syndrome” which seems to be of high predictive importance in young patients with chronic kidney disease (CKD) on renal replacement therapy [1]. The authors investigated heart changes, using imaging techniques for structural study and sensitive biomarkers to assess myocardial function and metabolism, in order to examine the association of these parameters with left ventricular hypertrophy (LVH). They calculated that cardiac magnetic resonance (CMR) and MR spectroscopy (MRS) allow the detection of cardiac dysfunction earlier. They also concluded that young patients with advanced CKD and normal ejection fraction demonstrated early cardiac impairments accompanied by increased LV mass index, which suggested a development of maladaptive hypertrophy. In this regard, we would like to pay attention to our observations made in children with CKD, which revealed the usefulness of a non-invasive 87-electrode electrocardiographic method, BSPM (body surface potential mapping), in early detection of intraventricular conduction disturbances of various degrees. We have used isochrone maps that precisely reflect ventricular activation time (VAT maps). In the examined CKD children treated conservatively [2] or with renal replacement [3], the maps showed a varied abnormal distribution of prolonged VAT values, which suggested obstacles in the intraventricular conduction pathway. In patients hemodialyzed up to 12 months, the pattern specific for left bundle branch block (LBBB) was found, and after renal transplantation essential alleviation occurred, with a transformation to the left anterior fascicle block pattern. The patients hemodialyzed over 12 months manifested more significant disturbances of the complete LBBB type that were normalized after transplantation to the incomplete LBBB pattern. It is noteworthy that all patients demonstrated neither conduction abnormalities on standard ECG, nor left ventricular hypertrophy or compromised cardiac systolic function in echocardiography. Our results, being in strong relevance to the findings of Malatesta-Muncher et al., suggest that children with CKD, regardless of mechanisms responsible for LVH, adaptive or maladaptive, are at risk of developing progressive abnormalities in the intraventricular heart conduction system. Such disturbances of electrical activation propagation lead to delayed ventricular depolarization, which results in D. Polak-Jonkisz (*) Department of Pediatric Nephrology, Wroclaw Medical University, Borowska 213, Wroclaw 50-556, Poland e-mail: dorota.polak-jonkisz@am.wroc.pl

Orthodromic atrioventricular reciprocating tachycardia conducted with intraventricular conduction disturbance mimicking ventricular tachycardia in an English Bulldog

Electrocardiographic tracings of an English Bulldog referred for cardiogenic shock due to an orthodromic atrioventricular reciprocating tachycardia conducted with intraventricular conduction disturbance and mimicking ventricular tachycardia (VT) are presented. At admission the surface ECG showed a wide QRS complex tachycardia (WCT) that was converted to sinus rhythm using manual cardioversion (chest thump). This change revealed pre-existing right bundle branch block, and a final diagnosis of supraventricular tachycardia (SVT) with intraventricular conduction disturbance was made. Electrophysiologic study defined the SVT mechanism as an atrioventricular macroreentrant tachycardia mediated by a single mid-septal accessory pathway. The differentiation between various types of WCT is essential when antiarrhythmic therapy is considered. The surface ECG should be systematically evaluated in order to recognize the characteristic features of SVT and VT. Moreover chest thump procedure can be very helpful in the attempt to convert the rhythm to sinus rhythm and to correctly recognize the underlying arrhythmia.

QRS pattern and improvement in right and left ventricular function after cardiac resynchronization therapy: a radionuclide study

BackgroundPredicting response to cardiac resynchronization therapy (CRT) remains a challenge. We evaluated the role of baseline QRS pattern to predict response in terms of improvement in biventricular ejection fraction (EF).MethodsConsecutive patients (pts) undergoing CRT implantation underwent radionuclide angiography at baseline and at mid-term follow-up. The relationship between baseline QRS pattern and mechanical dyssynchrony using phase analysis was evaluated. Changes in left and right ventricular EF (LVEF and RVEF) were analyzed with regard to baseline QRS pattern.ResultsWe enrolled 56 pts, 32 with left bundle branch block (LBBB), 4 with right bundle branch block (RBBB) and 20 with non-specific intraventricular conduction disturbance (IVCD). A total of 48 pts completed follow-up. LBBB pts had significantly greater improvement in LVEF compared to RBBB or non-specific IVCD pts (+9.6 ± 10.9% vs. +2.6 ± 7.6%, p = 0.003). Response (defined as ≥ 5% increase in LVEF) was observed in 68% of LBBB vs. 24% of non-specific IVCD pts (p = 0.006). None of the RBBB pts were responders. RVEF was significantly improved in LBBB (+5.0 ± 9.0%, p = 0.007), but not in non-specific IVCD and RBBB pts (+0.4 ± 5.8%, p = 0.76). At multivariate analysis, LBBB was the only predictor of LVEF response (OR, 7.45; 95% CI 1.80-30.94; p = 0.006), but not QRS duration or extent of mechanical dyssynchrony.ConclusionsPresence of a LBBB is a marker of a positive response to CRT in terms of biventricular improvement. Pts with non-LBBB pattern show significantly less benefit from CRT than those with LBBB.

Effect of kidney transplantation on heart conduction disturbances in children treated with chronic hemodialysis - A pilot study

Aim of the study was to assess the effect of KT on heart conduction in HD children. Non-invasive electrocardiographic method of BSPM was used. Isochrone maps, presenting a VAT distribution, were taken from eight HD patients and 26 normal subjects. Patients were divided into two groups: I--three children were HD <12 months prior to KT; II--five children were HD >12 months prior to KT. After KT, the groups were marked as IP and IIP. Serum iPTH and phosphate levels were significantly higher in both HD groups than in controls, with a considerable normalization after transplantation. HD patients demonstrated neither conduction abnormalities on ECG nor left ventricular hypertrophy. Group-mean VAT maps revealed: I and II--similar patterns of complete LBBB; IP--partial normalization to a pattern of anterior fascicle block; IIP--preserved pattern of LBBB. Intraventricular conduction disturbances found in HD children using BSPM were alleviated by KT. Short HD therapy increases a chance of conduction disturbances regression after KT, contrary to the longer HD treatment. BSPM is more sensitive than standard ECG in detecting heart conduction impairments in the HD patients.

Biventricular Implantable Cardioverter-defibrillator Post-implant Radiology: A Unique Image

A 72-year-old man was hospitalized for congestive heart failure and had a favorable response to the intensive medical treatment received. The patient had a history of ischemic heart disease with chronic anterior infarction of several years’ duration and three-vessel disease revascularized percutaneously some years previously. Two years before the current hospitalization, he underwent aortic valve replacement surgery with implantation of a biologic prosthesis to treat a severe double aortic valve lesion. The patient’s left ventricular systolic function was very depressed, he had an intraventricular conduction disturbance of the left bundle branch block type with QRS width >150 ms, and he required repeated hospitalization for heart failure despite optimized medical treatment. Within this clinical profile, the patient underwent implantation of an automatic defibrillator with cardiac resynchronization therapy, with no incidents. The follow-up posteroanterior (Fig. 1A) and lateral (Fig. 1B) chest radiographs showed well-positioned electrodes and multiple, randomly distributed, radio-opaque nodules predominating in the left chest wall, upper left extremity and supraclavicular region, and bilateral cervical areas, as well as the upper portion of the abdomen. These features corresponded to shotgun pellets acquired during a hunting accident 20 years previously that did not cause serious internal injury. However, on fluoroscopy during defibrillator implantation, one of the pellets was found to be located within the right ventricular myocardial wall, and was seen to rhythmically shift along with the tip of the electrode implanted in the apex of the ventricle (black arrow). Figure 1.

Heart ventricular activation in VAT difference maps from children with chronic kidney disease

Children with chronic kidney disease (CKD) are affected by cardiovascular complications, including disturbances in the intraventricular conduction system. Body surface potential mapping (BSPM) is a non-invasive method of assessing the cardioelectrical field. Our aim was to investigate conduction disturbances in young CKD patients using ventricular activation time (VAT) maps. Our study comprised 22 CKD children (mean age: 13.1 ± 2.5 years) treated conservatively and 29 control patients. For each child 12-lead electrocardiogram (ECG) readings were taken, and blood pressure and serum concentrations of iPTH, Pi, t-Ca, creatinine, Fe+3, ferritin, and Hb, as well as eGFR were measured. All children underwent registration in the 87-lead BSPM system, and group-mean VAT maps and a difference map, which presents statistically significant differences between the groups, were created. The VAT map distribution in CKD patients revealed abnormalities specific to left anterior fascicle block. The difference map displays the areas of intergroup VAT changes, which are of discriminative value in detecting intraventricular conduction disturbances. Intraventricular conduction impairments in the left bundle branch may occur in children with CKD. BSPM enables conduction disturbances in CKD children to be detected earlier than using 12-lead ECG. The difference map derived from the group-mean isochrone maps precisely localizes the sites of disturbed conduction in the heart intraventricular conduction system.

Effectiveness of Cardiac Resynchronization Therapy by QRS Morphology in the Multicenter Automatic Defibrillator Implantation Trial–Cardiac Resynchronization Therapy (MADIT-CRT)

This study aimed to determine whether QRS morphology identifies patients who benefit from cardiac resynchronization therapy with a defibrillator (CRT-D) and whether it influences the risk of primary and secondary end points in patients enrolled in the Multicenter Automatic Defibrillator Implantation Trial-Cardiac Resynchronization Therapy (MADIT-CRT) trial. Baseline 12-lead ECGs were evaluated with regard to QRS morphology. Heart failure event or death was the primary end point of the trial. Death, heart failure event, ventricular tachycardia, and ventricular fibrillation were secondary end points. Among 1817 patients with available sinus rhythm ECGs at baseline, there were 1281 (70%) with left bundle-branch block (LBBB), 228 (13%) with right bundle-branch block, and 308 (17%) with nonspecific intraventricular conduction disturbances. The latter 2 groups were defined as non-LBBB groups. Hazard ratios for the primary end point for comparisons of CRT-D patients versus patients who only received an implantable cardioverter defibrillator (ICD) were significantly (P < 0.001) lower in LBBB patients (0.47; P < 0.001) than in non-LBBB patients (1.24; P = 0.257). The risk of ventricular tachycardia, ventricular fibrillation, or death was decreased significantly in CRT-D patients with LBBB but not in non-LBBB patients. Echocardiographic parameters showed significantly (P < 0.001) greater reduction in left ventricular volumes and increase in ejection fraction with CRT-D in LBBB than in non-LBBB patients. Heart failure patients with New York Heart Association class I or II and ejection fraction ≤ 30% and LBBB derive substantial clinical benefit from CRT-D: a reduction in heart failure progression and a reduction in the risk of ventricular tachyarrhythmias. No clinical benefit was observed in patients with a non-LBBB QRS pattern (right bundle-branch block or intraventricular conduction disturbances). URL: http://www.clinicaltrials.gov. Unique identifier: NCT00180271.

Electrocardiographic changes in hospitalized patients with leptospirosis over a 10-year period

SummaryBackgroundThe aim of this study was to investigate the incidence and type of ECG changes in patients with leptospirosis regardless of clinical evidence of cardiac involvement.Material/MethodsA total of 97 patients with serologically confirmed leptospirosis treated at the University Hospital for Infectious Diseases „Dr. Fran Mihaljević‟ in Zagreb, Croatia, were included in this retrospective study. A 12-lead resting ECG was routinely performed in the first 2 days after hospital admission. Thorough past and current medical history was obtained, and careful physical examination and laboratory tests were performed.ResultsAbnormal ECG findings were found in 56 of 97 (58%) patients. Patients with abnormal ECG had significantly elevated values of bilirubin and alanine aminotransferase, lower values of potassium and lower number of platelets, as well as more frequently recorded abnormal chest x-ray. Non-specific ventricular repolarization disturbances were the most common abnormal ECG finding. Other recorded ECG abnormalities were sinus tachycardia, right branch conduction disturbances, low voltage of the QRS complex in standard limb leads, supraventricular and ventricular extrasystoles, intraventricular conduction disturbances, atrioventricular block first-degree and atrial fibrillation. Myopericarditis was identified in 4 patients. Regardless of ECG changes, the most commonly detected infection was with Leptospira interrogans serovar Australis, Leptospira interrogans serovar Saxkoebing and Leptospira kirschneri serovar Grippotyphosa.ConclusionsThe ECG abnormalities are common at the beginning of disease and are possibly caused by the direct effect of leptospires or are the non-specific result of a febrile infection and metabolic and electrolyte abnormalities. New studies are required for better understanding of the mechanism of ECG alterations in leptospirosis.

Diagnostic criteria of broad QRS complex tachycardia: decades of evolution

Broad QRS complex tachycardia still presents a diagnostic challenge when confronted with a 12-lead electrocardiogram (ECG). The ECG differential diagnosis includes ventricular tachycardia vs. supraventricular tachycardia with functional aberration, pre-existing bundle branch block, intraventricular conduction disturbances, or pre-excitation. Despite all available criteria, broad complex tachycardias are still misdiagnosed or remain undiagnosed. This paper will briefly review the most recognized criteria.