Intraventricular Conduction Blocks Research Articles

Cardiac arrhythmias and conduction abnormalities in patients with type 2 diabetes

The association between type 2 diabetes (T2D) and the development of cardiac arrhythmias and conduction disturbances has not been extensively studied. Arrhythmia was defined as atrial fibrillation and flutter (AF/AFl), ventricular tachycardia (VT) and ventricular fibrillation (VF), and conduction abnormality as sinus node disease (SND), atrioventricular (AV) block or pacemaker implantation, and intraventricular conduction blocks (IVCB). Incidence rates and Cox regression were used to compare outcomes, and to assess optimal levels for cardiometabolic risk factors and risk associated with multifactorial risk factor control (i.e., HbA1c, LDL-C, systolic blood pressure (SBP), BMI and eGFR), between patients with versus without T2D. The analyses included data from 617,000 patients with T2D and 2,303,391 matched controls. Patients with diabetes and the general population demonstrated a gradual increase in rates for cardiac conduction abnormalities and virtually all age-groups for AF/AFI showed increased incidence during follow-up. For patients with versus without T2D, risks for cardiac arrhythmias were higher, including for AF/AFl (HR 1.17, 95% CI 1.16–1.18), the composite of SND, AV-block or pacemaker implantation (HR 1.40, 95% CI 1.37–1.43), IVCB (HR 1.23, 95% CI 1.18–1.28) and VT/VF (HR 1.08, 95% CI 1.04–1.13). For patients with T2D who had selected cardiometabolic risk factors within target ranges, compared with controls, risk of arrythmia and conduction abnormalities for T2D vs not were: AF/AFl (HR 1.09, 95% CI 1.05–1.14), the composite of SND, AV-block or pacemaker implantation (HR 1.06, 95% CI 0.94–1.18), IVCB (HR 0.80, 95% CI 0.60–0.98), and for VT/VF (HR 0.97, 95% CI 0.80–1.17). Cox models showed a linear risk increase for SBP and BMI, while eGFR showed a U-shaped association. Individuals with T2D had a higher risk of arrhythmias and conduction abnormalities than controls, but excess risk associated with T2D was virtually not evident among patients with T2D with all risk factors within target range. BMI, SBP and eGFR displayed significant associations with outcomes among patients with T2D.

Ventricular conduction abnormalities and associated outcome among reduced ejection fraction to mid-range heart failure patients

Intra-ventricular conduction blocks can impair prognosis of heart failure (HF), but their specific impact is not well established, sometimes even controversial. This study aimed to analyse the clinical profile and outcomes of HF patients with left bundle branch block (LBBB), right bundle branch block (RBBB), IVCD (intra-ventricular conduction delay) and left anterior fascicular block (LAFB). A total of 187 patients with reduced ejection fraction to mid-range HF, were enrolled in this study. They were sub grouped within their electrical morphology into respectively: LBBB (24%), RBBB (7.5%), IVCD (8%), LAFB (10.5%) and narrow QRS (< 110ms; 43.5%). We analyzed their baseline clinical variables and outcomes after a median follow-up of 22 months [IQR:10–33]. Survival was assessed using multiple Cox regression analysis. LBBB was associated with more marked LV dilation ( P = 0.018). Patients with RBBB, presented overt signs of congestive HF ( P = 0.045) and depressed right ventricular motion ( P = 0.019). Those with IVCD, had intermediate echocardiographic characteristics between LBBB an RBBB. The LAFB group reported more history of coronary heart disease ( P = 0.029). Death occurred in 57 patients. Univariate survival analyses, showed that patients with RBBB had higher risk of cardiac death and pump failure readmissions in comparison to LBBB ( P = 0.023); and narrow QRS (all-cause mortality: P = 0.01; pump failure readmissions: P = 0.009). After multiple covariate adjustment, RBBB was an independent risk factor for all-cause mortality ( P = 0.047). HF patients presenting with intra-ventricular conduction blocks had significantly different clinical profiles. RBBB had greater clinical severity and was associated with higher risk of mortality and pump failure re-hospitalization and was an independent predictor of all-cause mortality. LBBB had more severe echocardiographic characteristics but in contrast, did not predict worse outcome.

Intraventricular conduction blocks in Nigerians with hypertensive heart disease

Background: Hypertension is highly prevalent in Nigeria and globally. Intraventricular conduction blocks contribute to morbidity and mortality in hypertension. The objective of the study was to determine the prevalence and pattern of intraventricular conduction blocks in adult Nigerians with hypertensive heart disease. Materials and methods: This was a retrospective study of the resting 12-lead electrocardiograms of adult patients with hypertensive heart disease attending the Cardiology Unit of the Federal Medical Centre (FMC), Ido-Ekiti, Nigeria. The data collected was doubly entry into SPSS 20.0 software. Results: Resting electrocardiograms of 543 adult Nigerians with hypertensive heart disease were studied. There were 336 (61.9%) males and 207 (38.1%) females. Mean age and standard deviation of the patients was 61.3±9.7 years. About a quarter (24.7%) of the patients had intraventricular conduction blocks. Left anterior fascicular block was the most common (52.2%) occurring singly or in combinations with other blocks. Intraventricular conduction blocks were more prevalent in patients with hypertensive heart failure (31.0% versus 23.9%, p = 0.24)though not statistically significant. Conclusion: This study shows that there is a high prevalence of intraventricular conduction blocks in adult Nigerians with hypertensive heart disease. The subset with heart failure has a higher prevalence than those without heart failure. Left anterior fascicular block is the most common type. Key words: Hypertension, heart failure, intraventricular conduction blocks, adult Nigerians

Association between cardiac disorders and a decades-previous history of diphtheria

A long, prior history of diphtheria is common among middle-aged and elder European adults. The aim of the present study was to determine whether the risk of reduced ventricular function and impaired intraventricular conduction is increased in individuals with a history of diphtheria. A study population of 2,480 subjects (1,222 women) aged 45 years or older who were recruited for the Study of Health in Pomerania were available for the present analyses. Left ventricular function was assessed by echocardiography. Intraventricular conduction blocks were diagnosed using electrocardiograms. Multivariable analyses revealed that individuals with a history of diphtheria had neither an increased odds for reduced fractional shortening (OR 1.21, 95% CI 0.69-2.11; p=0.51) nor an increased odds for intraventricular conduction blocks (OR 0.90, 95% CI 0.55-1.46; p=0.67). However, regression models revealed two-way interactions between the exposure variable and hypertension with respect to both endpoints. A history of diphtheria increased the odds for both endpoints in normotensive but not in hypertensive individuals. The findings show that a history of diphtheria several decades previously in a patient is a risk marker for reduced cardiac function and impaired intraventricular conduction in individuals at low risk for these disorders.

Electrocardiographic manifestations: bundle branch blocks and fascicular blocks

Intraventricular conduction block is the general name given to a varied group of electrocardiographic entities. All share a common finding of some degree of delay in ventricular activation; recognition of these blocks hinges upon analysis of the QRS complex, as well as the ST-T changes associated with them. Bundle branch block (right or left), and fascicular block (left anterior or left posterior) are all examples of intraventricular conduction block. Causation of intraventricular conduction block may be cardiac or noncardiac; early recognition of the etiology may be of clinical importance. This article reviews the basic anatomy and physiology related to intraventricular conduction blocks, and then examines each in terms of electrocardiographic definition and clinical correlation.

Comparison of the Action Mechanisms of Gonyautoxins and Tetrodotoxi on the Cardiovascular System in the Rabbit

We investigated the effects of gonyautoxins (GTXs) and tetrodotoxin (TTX) on cardiovascular function in 60 adult rabbits following injections of oxprenolol (β-blocker) or oxprenolol (β-blocker) and phentolamine (α-blocker). The effects of GTXs (3.0, 5.0 or 7.0 MU/kg, i. v.) and TTX (5.0, 7.0 or 11.3 MU/kg, i. v.) on cardiovascular function were assessed by measuring the electrocardiogram (ECG) and mean aortic pressure (MAP) changes in anesthetized rabbits. The ECG was monitored with A-B lead and MAP with a cathetertransducer system. In rabbits pretreated with oxprenolol (0.1mg/kg, i. v.), atrioventricular and intraventricular conduction blocks were observed but the same arrhythmia as in the intact animal was not observed after the administration of GTXs, while no remarkable effects of TTX on the cardiac function were apparent in the ECG. In rabbits treated with both phentolamine (0.05mg/kg, i. v.) and oxprenolol (0.1mg/kg, i. v.), ECG findings after the injection of GTXs or TTX were similar to those observed in the animals given only oxprenolol. GTXs induced hypotension whereas TTX had no effect on MAP except at higher dose. These results suggest that TTX depresses the sympathetic cardiac nerves and the arteriolar muscles at higher dose, while GTXs facilitate the sympathetic cardiac nerves but directly depress the cardiac and the arteriolar muscles.

Intraventricular conduction blocks. Part I. Introduction and electrocardiographic identification of right and left bundle branch block

Intraventricular conduction blocks. Part I. Introduction and electrocardiographic identification of right and left bundle branch block

Clinical and anatomic implications of intraventricular conduction blocks in acute myocardial infarction.

The electrocardiogram in 480 patients with acute myocardial infarction showed right bundle-branch block (RBBB) with normal QRS axis in 18 patients (3.7%), left bundle-branch block (LBBB) in 31 (8%), RBBB and left anterior hemiblock (LAH) in 23 (4.8%), RBBB and left posterior hemiblock (LPH) in four (1%), LAH alone in 20 (4%), LPH in one (0.2%), and no evidence of intraventricular conduction (I-V) disturbance in 383 (80%). Eighteen of the 97 patients with I-V block showed 1° A-V block, and seven of the 18 (39%) showed abrupt progression to high-grade A-V block, while only six of 79 (8%) without 1° A-V block showed similar progression. Cause of death in patients with I-V block was cardiac failure and/or shock in 92%; only three instances of primary asystole occurred. The incidence of complete heart block was higher in the I-V disease group (15%) than in the group without block (5%), but not significantly. Patients with LAH or RBBB and LAH usually had occlusion of the left anterior descending artery with extensive septal infarction, while patients with RBBB or LBBB had a more variable pattern of vessel involvement. Presence of I-V block in patients with acute myocardial infarction implies a hectic clinical course with poor prognosis, but does not justify prophylactic temporary transvenous intracardiac pacing except perhaps in the subgroup with associated 1° A-V block.