Normal Structural Heart Research Articles

Fractured epicardial lead in paediatric patients: can they be safely repaired?

Abstract Funding Acknowledgements Type of funding sources: None. Background/Introduction Before bipolar epicardial leads became widely available and used by heart surgeons, unipolar epicardial leads were frequently implanted in small children requiring permanent pacing. Main complications are lead fractures causing pacing/sensing defect. Therefore, patients should undergo new epicardial or endocardial lead implantation with relevant procedural risks, especially in complex congenital heart disease (CHD). Proximal fractures, close to the generator, may be repaired using a dedicated Unipolar Lead Adapter and Extension, with reduced operative risks. Purpose of the study is the retrospective analysis of the outcome of the repair of unipolar epicardial leads in young patients (pts) in a single tertiary paediatric center. Methods Consecutive patients with proximal fracture underwent a trial of lead repair using the lead adapter/extension, during general anaesthesia, cefuroxime antibiotic profilaxis, from 2004 to 2020. Lead data (threshold, sensing, impedance) were compared before and after the repair procedure. Results 18 patients with CHD (12pts, 10 of whom complex, 6 post-Fontan) or normal structural heart (6pts), who underwent pacemaker implantation at 2.5 (0.7-5.8)years of age for congenital/postoperative atrioventricular block (11pts) and sinus node dysfunction (7pts), showed lead (7 atrial, 11 ventricular) fractures after chronic pacing. At 13 (8-17)years of age, all leads were successfully repaired without any complications. Follow-up was 4 (2-6)years. Four pts (22%) showed again fractures of the repaired lead, after 1 month, 1and 3 years (2pts). Electrical lead parameters are shown in table 1: there were not significant differences between consecutive time of controls, also in the atrial and ventricular lead subgroups. Table 1.-------------------Pre-repair;--intraprocedural;---1 month;----------1 year;-------------4 years. Threshold (V/0.4 ms):--1.1 (0.7-1.4);--1.0 (0.8-1.6);-------1.2 (0.9-1.5);-----1.2 (0.9-2.1);-------1.5 (1.1-1.8). Sensing (mV):--------- 7 (2.4-12);------5.4 (1.3-15);-------4 (1.5-11);----------5 (1.6-12);---------3 (2-10). Impedance (ohm): 343 (289-407);---350 (246-415);--346 (250-432);--374 (250-589);--362 (220-470). Conclusion The repair of fractured unipolar epicardial leads in young patients is a safe and effective procedure, with few complications during follow-up. Effective repair can delay more aggressive procedures.

ACMG SF v3.0 list for reporting of secondary findings in clinical exome and genome sequencing: a policy statement of the American College of Medical Genetics and Genomics (ACMG)

ACMG SF v3.0 list for reporting of secondary findings in clinical exome and genome sequencing: a policy statement of the American College of Medical Genetics and Genomics (ACMG)

Minimising radiation exposure in catheter ablation of ventricular arrhythmias

BackgroundConventional fluoroscopy guided catheter ablation (CA) is an established treatment option for ventricular arrhythmias (VAs). However, with the complex nature of most procedures, patients and staff bare an increased radiation exposure. Near-zero or zero-fluoroscopy CA is an alternative method which could substantially reduce or even eliminate the radiation dose. Our aim was to analyse procedural outcomes with fluoroscopy minimising approach for treatment of VAs in patients with structurally normal hearts (SNH) and structural heart disease (SHD).MethodsFifty-two (age 53.4 ± 17.8 years, 38 male, 14 female) consecutive patients who underwent CA of VAs in our institution between May 2018 and December 2019 were included. Procedures were performed primarily with the aid of the three-dimensional electro-anatomical mapping system and intra-cardiac echocardiography. Fluoroscopy was considered only in left ventricular (LV) summit mapping for coronary angiography and when epicardial approach was planned. Acute and long-term procedural outcomes were analysed.ResultsSixty CA procedures were performed. Twenty-five patients had SHD-related VAs (Group 1) and 27 patients had SNH (Group 2). While Group 1 had significantly higher total procedural time (256.9 ± 71.7 vs 123.6 ± 42.2 min; p < 0.001) compared to Group 2, overall procedural success rate [77.4% (24/31) vs 89.7% (26/29); p = 0.20)] and recurrence rate after the first procedure [8/25, (32%) vs 8/27, (29.6%); p = 0.85] were similar in both groups. Fluoroscopy was used in 3 procedures in Group 1 where epicardial approach was needed and in 4 procedures in Group 2 where LV summit VAs were ablated. Overall procedure-related major complication rate was 5%.ConclusionsFluoroscopy minimising approach for CA of VAs is feasible and safe in patients with SHD and SNH. Fluoroscopy could not be completely abolished in VAs with epicardial and LV summit substrate location.

Can hypoglycemic episodes in type 1 diabetics trigger cardiac arrhythmias?

BackgroundSudden nocturnal death is a syndrome that usually affects patients with diabetes mellitus type 1 (DM1), being described mainly due to ventricular arrhythmias in response to nocturnal hypoglycemia. ObjectivesEvaluate the relation between hypoglycemia and ventricular arrhythmias in patients with DM1 and normal structural heart. MethodProspective, observational study with DM1 patients and normal structural heart on echocardiogram aged 18–60 years, of both sexes receiving insulin therapy for at least five years. Intermittent glucose reading device was implanted (iPro2 – Medtronic/USA) and 24hr ambulatory electrocardiographic recording by the Holter system (Cardios Systems – Brazil). Patients were monitored for hypoglycemia without any type of induction (interstitial glucose <70 mg/dl) and cardiac arrhythmias within 24 h. ResultsThirty-two patients were evaluated, with mean-age of 35 years, being 16 men. Eleven patients (34%) did not have hypoglycemia, other 3 (27.3%) also had no arrhythmia, while 8 (72.7%) had arrhythmias interpreted as irrelevant. The other 21 patients (66%) presented some hypoglycemic episodes and 10 (47.6%) did not present arrhythmias, whereas 11 (52.4%) presented arrhythmias considered not clinically significant, as also found in non-diabetic individuals. ConclusionIn patients with DM1 without structural heart disease there was no relationship between cardiac arrhythmia and episodes of hypoglycemia.

Brugada Syndrome: Progress in Genetics, Risk Stratification and Management.

Brugada syndrome (BrS) is one of the most common causes of sudden cardiac death in normal structural heart individuals. First characterised in 1992, the global prevalence of BrS is unclear, with estimates placing it at around 0.05% and presenting most frequently in southeast Asian countries. This review aims to summarise the development in the understanding of BrS and, importantly, progress in its management, underpinned by knowledge regarding its genetics and molecular mechanisms. It also provides update on risk stratification and promising new therapies for BrS, including epicardial ablation. Future studies are required to increase understanding of the pathogenesis of this disease and to guide clinical practice.

The effects of interleukin 17A on left stellate ganglion remodeling are mediated by neuroimmune communication in normal structural hearts

BackgroundIt is reported interleukin (IL)-17A, a classical proinflammatory cytokine, is implicated in neuroimmune-associated remodeling in neural plasticity and pathological conditions. However, the effect of IL-17A on left stellate ganglion (LSG) remodeling remains unclear. ObjectiveThis study was performed to determine whether exogenous IL-17A promotes LSG remodeling and destabilize ventricular electrophysiological properties (EPs) in normal canines. Methods24 beagles were randomly allocated into three groups. In the first group, animals were subjected to 0.1 ml phosphate buffer saline (PBS) microinjection of into LSG (n = 8), an equivalent IL-17A was administrated in the second group (n = 8), and an equivalent anti-IL-17A mAb plus IL-17A was administrated in the third group (n = 8). The ventricular EPs, neural function and activity of the LSG were determined at baseline and 30 min after administration. In the end, LSG tissues were collected. ResultsCompared with the control group, the experimental group had a significantly shorter effective refractory period (ERP) and action potential duration (APD)90, an increased ERP, APD90, Smax dispersion, and APD alternans cycle length; and steepened APD restitution curves. In addition, IL-17A enhanced the neural function and activity of the LSG, upregulated the expressions of neuropeptides and proinflammatory cytokines and cells. And all these effects were attenuated by anti-IL-17A mAb. Importantly, IL-17 receptor A (IL-17R-A) was detected in sympathetic neurons in the LSG. ConclusionIL-17A promoted LSG remodeling by regulating the neural inflammation response. It did so by binding to IL-17R-A, resulting in unstable ventricular electrophysiology in normal structural hearts.

Pregnancy with uncorrected tetralogy of Fallot (TOF), pulmonary atresia and major aorto-pulmonary collateral arteries (MAPCA)

Abstract Pregnancy with uncorrected tetralogy of Fallot (TOF) is a rare event, and increases the risk for fetal growth restriction and adverse outcomes related to worsening right-to-left shunt, cyanosis, pulmonary hypertension and arrhythmia. Obstetric management is made on a case-by-case basis. Patients who remain stable can achieve term pregnancies and the mode of delivery can be based on obstetric indications. We present the case of a 21-year-old primigravida with baseline cyanosis, oxygen saturation 90% at rest (74% with activities), hematocrit 50%, and echocardiogram showing pulmonary atresia, ventricular septal defect (VSD), and major aorto-pulmonary collateral arteries (MAPCA). We managed her with aspirin, metoprolol and oxygen supplementation. She delivered at 38 weeks (fetal growth restriction) via cesarean; she received epidural and endocarditis prophylaxis. Three years later, she presented pregnant and had a repeat cesarean at term. Both newborns had normal structural hearts. Knowledge of the cardiovascular physiology during pregnancy and baseline assessment, and a multidisciplinary management are key aspects in the management of these cases during pregnancy.

Evaluation of right ventricular function in patients with complete right bundle branch block with normal structural heart

Background: The impact of a RBBB in cases with structural heart disease on cardiac function has been evaluated extensively. However, literature about the impact of an isolated complete RBBB without structural heart disease on cardiac function of the right ventricle is limited. Aim: To assess right ventricular function in patients with complete RBBB in normal structural heart patients Material and Methods: Hospital based observational study in 100 patients aged ? 18 years. Cases (50) consisted of patients with isolated complete right bundle branch blocks without structural heart disease while the control group consisted of 50 healthy adults. The diameter, end-diastolic area, end-systolic area, and right ventricular (RV) fractional area ,pulse wave tissue velocity at lateral tricuspid annulus ,TAPSE and E/A ratio were obtained to evaluate RV morphologic and systolic and diastolic function . Results : Although ,the measurements of RA area ,RV basal dimension , RV fractional area change ,TAPSE ,RIMP and S' at lateral tricuspid tissue annulus were in normal limits in block group but there was statistical significant difference in between the patients with blocks and controls(p <0.05 ) . The myocardial performance index (Tei index) of the lateral tricuspid tissue annulus was significantly increased. Chi square test and t test was applied to compare the same variable between the group and p value of ? .05 was considered statistically significant. Conclusions : In patients with isolated complete right bundle branch blocks, systolic and diastolic functions are impaired in the RV and follow-up is needed.

Ablation of Atrial Fibrillation: Patient Selection, Periprocedural Anticoagulation, Techniques, and Preventive Measures After Ablation.

Atrial fibrillation (AF) is the most common arrhythmia encountered by cardiologists and is a major cause of morbidity and mortality. Risk factors for AF include age, male sex, genetic predisposition, hypertension, diabetes mellitus, sleep apnea, obesity, excessive alcohol, smoking, hyperthyroidism, pulmonary disease, air pollution, heart failure, and possibly excessive exercise. The management of AF involves decisions about rate versus rhythm control. Asymptomatic patients are generally managed with rate control and anticoagulation. Symptomatic patients will desire rhythm control. Rhythm control options are either antiarrhythmic agents or ablation, with each having its own risks and benefits. Ablation of AF has evolved from a rare and complex procedure to a common electrophysiological technique. Selection of patients to undergo ablation is an important aspect of AF care. Patients with the highest success rates of ablation are those with normal structural hearts and paroxysmal AF, although those with congestive heart failure have the greatest potential benefit of the procedure. Although pulmonary vein isolation of any means/energy source is the approach generally agreed on for those with paroxysmal AF, optimal techniques for the ablation of nonparoxysmal AF are not yet clear. Anticoagulation reduces thromboembolic complications; the newer anticoagulants have eased management for both the patient and the cardiologist. Aggressive management of modifiable risk factors (hypertension, diabetes mellitus, sleep apnea, obesity, excessive alcohol, smoking, hyperthyroidism, pulmonary disease, air pollution, and possibly excessive exercise) after ablation reduces the odds of recurrent AF and is an important element of care.

Prevalence and characteristics of myocardial crypts in Japanese patients referred for cardiovascular magnetic resonance

Background Myocardial crypts are narrow, blood-filled invaginations within the left ventricle (LV) wall and detected by cardiovascular magnetic resonance (CMR). Recent studies show that a higher prevalence of crypts in patients with hypertrophic cardiomyopathy (HCM) and genotype positive but phenotype negative relatives. Other studies show that myocardial crypts are relatively common in the normal population and incidental variants of local myocardial structures. However, these studies were performed in the western countries and the prevalence and kinds of HCM are different between Japanese and Western people. We aimed to investigate the prevalence and characteristics of myocardial crypts in Japanese people by using CMR. Methods We examined retrospectively 266 consecutive patients (mean age 63.0±15.4 years, 65.8% male) referred for CMR. Crypts were defined as >50% invagination into normal myocardium. We performed 1.5T cardiac MRI including conventional cine imaging and late gadolinium enhancement (LGE) imaging. The location and the number of crypts were evaluated by using a 17-segment model. The prevalence of crypts was compared between patients groups. We also investigated the location of LGE, family history and the first recognition of abnormal ECG in the patients with crypts. Results Crypts were identified in 12 patients (4.5%). Among them, ten patients were with HCM (83%) and 1 patient with congenital heart disease and 1 patient with arrhythmia but with normal structural heart. The prevalence of myocardial crypt is significantly higher in patients with HCM (10 of 82: 12.2%) than in patients without HCM (2 of 184: 1.1%) (P=0.0002). In 10 patients with HCM and crypt, 3 patients had apical hypertrophy. There was no significant difference in prevalence of crypts between HCM patients with apical hypertrophy and those without apical hypertrophy (3 of 23:13.0%, 7 of 59: 11.8%, respectively). Eight patients had single crypt and 4 patients had multiple crypts. All patients had at least one crypt at LV basal level and most popular location was LV basal inferior wall (10 patients). LGE was found in 6 patients and all were with HCM. Two patients had LGE in the same segment with crypt. There were 5 patients with HCM with family histories of sudden death or LV hypertrophy or dilated cardiomyopathy, but no patient without HCM had family history. Abnormal ECG findings were detected under age of 20 in four patients with HCM but in no patients without HCM. Conclusions Myocardial crypts were more frequently seen in the patients with HCM and also seen in the patients with other cardiac diseases in Japan. Although genetic tests were not performed in these patients, genetic factors were suggested in the patients with myocardial crypts and HCM. Funding N/A.

Ventricular tachycardia originating from the septal papillary muscle of the right ventricle: electrocardiographic and electrophysiological characteristics.

Premature ventricular complexes (PVCs) and ventricular tachycardia (VT) arising from papillary muscles of both ventricles have recently been described. There is a lack of data on VT originating from the right ventricular papillary (RV PAP) muscles. There have been no prior studies focused on the electrocardiogram (ECG) features and ablation of PVC/VT arising from the septal papillary muscle of the right ventricle. Among 155 consecutive patients with normal structural heart who underwent catheter ablation of PVC/VT, 8 patients with PVC/VT from the septal RV PAP muscle were identified. The site of origin of the arrhythmias was identified through activation/pace mapping and intracardiac echocardiography. All patients underwent radiofrequency ablation of the arrhythmia. Data on 8 consecutive patients (2 men, age 42 ± 13 years old) were collected. All patients had a preserved ejection fraction (60 ± 4%). Septal RV PAP arrhythmias had a left superior axis and negative concordance or late R-wave transition in precordial leads. PVCs were spontaneous in 5 cases, were induced by isoprotenerol in 2 cases and by isoproterenol plus phenylephrine in another one. PVCs were never induced with calcium bolus and only rarely with burst pacing. Adenosine never terminated VT or suppressed the VT/PVCs. Radiofrequency, fluoroscopic, and procedural time were, respectively, 10.3 ± 3, 36.4 ±11.3, and 76.3 ± 27.5 minutes. During a mean follow-up of 8 ± 4 months, mean PVC burden was reduced from 14 ± 3% preablation to 0.1 ± 0.2% postablation. PVCs and VT originating from septal RV papillary muscle could have a typical ECG pattern due to the site of the muscle involved. Radiofrequency ablation of this anatomic area is feasible and effective.

Ventricular fibrillation triggered by PVCs from papillary muscles: clinical features and ablation.

Animal studies showed that papillary muscles can be sources of ventricular fibrillation (VF) in both the left and right ventricle, but this occurrence in humans has been described only in patients with ischemic heart disease. To investigate the role of papillary muscle premature ventricular contractions (PVCs) as triggers for VF and the safety and feasibility of catheter ablation in these patients. Six patients (2 male; age, 40 ± 11 years; 5 with a normal structural heart and 1 with nonischemic cardiomyopathy) with history of VF resulting in repetitive implantable cardioverter defibrillator shocks, despite antiarrhythmic drug therapy, and a papillary muscle focus of PVCs triggering VF were included and underwent mapping and ablation of PVCs. PVCs were observed to trigger VF and localized by mapping the earliest activation point that matched pace mapping of the same area. In 2 patients, PVCs originated from the left ventricle at the posteromedial papillary muscle; in 4 patients, PVCs originated from the right ventricle, at the posterolateral papillary muscle. Elimination of the triggering PVC was obtained in these areas after 19 ± 12 minutes by radiofrequency application. During a follow-up of 58 ± 11 months using ambulatory monitoring and defibrillator memory interrogation, no patients had recurrence of symptomatic ventricular arrhythmias. Papillary muscles from both ventricles represent an anatomic structure potentially involved in the onset of VF, also in normal structural heart. PVCs arising from this area can be successfully eliminated by radiofrequency ablation, resulting in freedom from recurrent VF at long-term follow-up.

The feasibility and correlation of atrial fibrillation vulnerability test to the indices of atrial substrates using atrial burst decremental pacing

Pulmonary vein isolation and atrial substrate modification using catheter ablation have been developed as a standard treatment for atrial fibrillation (AF). However, the standard end-point for these procedures is still not well established. This study aimed to investigate the characteristics among positive and negative AF vulnerability patients with normal structural heart, in order to define the endpoint of the atrial substrate modification. Fifty supraventricular tachycardia patients with normal heart structure referred for electrophysiological study and catheter ablation were enrolled. After eliminating the underling arrhythmias, the basic cycle length, effective refractory period of the right atrium, and the P wave indices in 12-lead electrocardiograms were measured. The AF vulnerability test was performed by atrial burst decremental pacing with a pacing cycle length decreasing from 290 ms to 200 ms. The AF vulnerability test was considered as positive when the duration of the induced AF or atrial tachyarrhythmias (ATs) was longer than 10 seconds. The parameters of atrial substrates were compared between patients with positive and negative values of the AF vulnerability test. ATs or AF were induced in 24 (48%) patients. Among these patients, 12 (24%) induced ATs or AF were found to be sustained (duration more than 10 seconds). However, only two of these patients could reproduce the positive result after 10 minutes of the first induced protocol. Comparing the patient baseline characteristics, P wave characteristics and cardiac echo parameters, there were no significant differences between the positive and negative AF vulnerability groups. In conclusion, AF and ATs could be induced in patients with a structurally normal heart. The traditional clinical indices of atrial substrates were not significantly different between the positive and negative AF vulnerability patients. Protocols other than atrial burst decremental pacing should be investigated to evaluate the endpoint of the atrial substrate modification.

Safety and outcomes of cryoablation for ventricular tachyarrhythmias: Results from a multicenter experience

Catheter ablation of ventricular arrhythmias (VAs) with cryoenergy has not been widely reported. The purpose of this study was to assess the feasibility and safety of cryoablation for VA. Cases where cryoablation of VA was attempted as the initial strategy or was considered to prevent potential damage to other structures such as the coronary arteries, phrenic nerve, and His bundle were collected. Thirty-three patients with either normal heart or structural heart disease undergoing VA ablation using cryoenergy at six different institutions were enrolled in the study. Epicardial access was obtained when appropriate. Fifteen patients (7 men) underwent endocardial ablation, 13 (9 men) epicardial ablation (from the coronary sinus in 7), and 5 (2 men) aortic cusp ablation. Mean age was 54 ± 8 years, and ejection fraction was 45% ± 5%. In 15 (45%) patients, VAs were successfully ablated, whereas cryoablation was unsuccessful in the remaining 18 (55%) patients. Cryoablation was successful in all parahisian cases (100%). In three patients, epicardial cryoablation was successful after several failed attempts with open irrigated catheter. An aortic dissection occurred during catheter placement in the aortic cusp. At follow-up of 24 ± 5 months, all patients with acute success were free from clinical VA. Use of cryoenergy for ablation of VA has excellent success for arrhythmias near the His bundle; however, success rates at other sites appear less favorable. Cryoablation may be considered as an alternative approach for reducing complications during ablation of VAs originating from sites close to other relevant cardiac structures (conduction system, coronary arteries, phrenic nerve) and, in rare cases, could be used epicardially when radiofrequency energy applications have failed.

Heart rate variability in patients with syncopes

Syncope may be the result of primary bradycardia or tachycardia, vasovagal syncope, or noncardiac syncope. Risk factors and outcome scores to predict prognosis in patients with syncope have been developed. Although these correlate with morbidity and mortality in patients with syncope, their relationship with the mechanism of syncope has not been investigated.The purpose of this study was to identify clinical predictors of primary bradycardia in a cohort of patients undergoing prolonged monitoring for unexplained syncope.One hundred nineteen patients underwent prolonged monitoring with an implantable or external loop recorder after assessment at a single-center, tertiary care arrhythmia service. Fifty-two patients with recurrent syncope during monitoring were classified according to the mechanism of syncope (International Study on Syncope of Uncertain Etiology [ISSUE] classification). Clinical predictors of primary arrhythmic syncope were identified.Twenty patients were classified with primary arrhythmia and 32 patients were classified with nonarrhythmic syncope. Five clinical variables were associated with primary arrhythmia: left bundle branch block, structural heart disease, and syncope without prodrome increased the likelihood of primary arrhythmia; a normal baseline ECG and history of syncope in childhood decreased the likelihood of primary arrhythmia. After multiple logistic regression, risk factors for the diagnosis of primary arrhythmia included syncope without warning symptoms and structural heart disease. The presence of left bundle branch block correlated perfectly with primary arrhythmia, whereas a normal ECG reduced the likelihood of primary arrhythmia.Clinical predictors of primary arrhythmia in patients with recurrent syncope include normal ECG and structural heart disease. Left bundle branch block is an important finding in patients with unexplained syncope.

Myocardial Apelin Production is Reduced in Humans With Left Ventricular Systolic Dysfunction

Background Apelin is a novel endogenous peptide with inotropic and vasodilatory properties that is the ligand for the APJ receptor. Apelin and APJ are widely distributed in the vasculature of a number of organs and peripheral venous apelin is reduced in heart failure (HF). The location of apelin production in humans with and without HF was investigated. Methods and Results Plasma apelin and brain natriuretic peptide (BNP) concentrations in coronary sinus (CS), aorta (Ao), and renal vein (RV) of individuals with HF (n = 9) were compared to subjects with normal structural hearts (n = 8). In HF the concentration of CS apelin was reduced compared with controls (310 pg/mL [interquartile range 290-390] vs. 470 pg/mL [340-570], P < .035) but Ao apelin (330 pg/mL [275-375] vs. 340 pg/mL [230-455], P = .76) and RV apelin (290 pg/mL [280-360] vs. 370 pg/mL [273-410], P = .56) were unchanged. Plasma BNP was increased at all sampling sites in patients with HF as compared with controls. A step down from CS to Ao to RV in all subjects was observed. The step down in apelin from CS to Ao (470 pg/mL [310-595] vs. 320 pg/mL [225-482], P < .04) in control subjects was not apparent in patients with HF. Conclusions These novel data show that apelin is produced in the human heart and that production is reduced in individuals with HF. In contrast to BNP, apelin production is not exclusive to the heart.

Predicting the cause of syncope from clinical history in patients undergoing prolonged monitoring

Syncope may be the result of primary bradycardia or tachycardia, vasovagal syncope, or noncardiac syncope. Risk factors and outcome scores to predict prognosis in patients with syncope have been developed. Although these correlate with morbidity and mortality in patients with syncope, their relationship with the mechanism of syncope has not been investigated. The purpose of this study was to identify clinical predictors of primary bradycardia in a cohort of patients undergoing prolonged monitoring for unexplained syncope. One hundred nineteen patients underwent prolonged monitoring with an implantable or external loop recorder after assessment at a single-center, tertiary care arrhythmia service. Fifty-two patients with recurrent syncope during monitoring were classified according to the mechanism of syncope (International Study on Syncope of Uncertain Etiology [ISSUE] classification). Clinical predictors of primary arrhythmic syncope were identified. Twenty patients were classified with primary arrhythmia and 32 patients were classified with nonarrhythmic syncope. Five clinical variables were associated with primary arrhythmia: left bundle branch block, structural heart disease, and syncope without prodrome increased the likelihood of primary arrhythmia; a normal baseline ECG and history of syncope in childhood decreased the likelihood of primary arrhythmia. After multiple logistic regression, risk factors for the diagnosis of primary arrhythmia included syncope without warning symptoms and structural heart disease. The presence of left bundle branch block correlated perfectly with primary arrhythmia, whereas a normal ECG reduced the likelihood of primary arrhythmia. Clinical predictors of primary arrhythmia in patients with recurrent syncope include normal ECG and structural heart disease. Left bundle branch block is an important finding in patients with unexplained syncope.

Electrical heart disease: Genetic and molecular basis of cardiac arrhythmias in normal structural hearts

Purely electrical heart diseases, defined by the absence of any structural cardiac defects, are responsible for a large number of sudden, unexpected deaths in otherwise healthy, young individuals. These conditions include the long QT syndrome, Brugada syndrome, catecholaminergic polymorphic ventricular tachycardia and the short QT syndrome. Collectively, these conditions have been referred to as channelopathies. Ion channels provide the molecular basis for cardiac electrical activity. These channels have specific ion selectivity and are responsible for the precise and timely regulation of the passage of charged ions across the cell membrane in myocytes, and the summation of their activity in cardiac muscle defines the surface electrocardiogram. Impairment in the flow of these ions in heart cells may mean the difference between a normal, prosperous life and the tragedy of a sudden, unexpected death due to ventricular arrhythmia. The present paper reviews the current clinical and molecular understanding of the electrical diseases of the heart associated with sudden cardiac death.

Age-Related Head-Up-Tilt Test Cardiac-Hemodynamic Profile in Vasovagal Syncope

Objective To determine the age-related cardio-hemodynamic profile (CHP) during head up tilt test (HUT) in patients with neurally mediated syncope (NMS). Methods 97 subjects (M/F=43/54) with a clinical history of NMS and normal structural heart underwent HUT (70°) 30-minute protocol. 73 patients had positive HUT response (mean time to syncope of 19±7 min) and were included for study analysis. Patients were divided in three study groups for comparison according to age: A = 66 years old (77±6). Beat-to-Beat heart rate (HR, bpm), mean blood pressure (MAP) and cardiac impedance were recorded and total peripheral resistance index (TPRI, dyne*s*m2/cm^5) and left ventricular work index (LVWI, mmHg*l/min/m2) were calculated using the Task Force Monitor (CNSystem, AU). Variables were compared at rest, 5 minutes of HUT (ES) and during -2 and -5 minutes prior to the onset of syncope. One-way ANOVA and Student's t test were applied. Results Variables are shown as means ± SD. Increased baseline HR was found in younger patients (Group A) compared with group B and C (76±15 vs. 67±12, p=0.017; 76±15 vs. 69±11, p=0.076). No statistical differences were found in MAP during HUT comparing groups. TPRI and LVWI are shown in the table as follows ![Graphic][1] Conclusion Distinct age-related CHP alterations can be documented in patients with NMS provoked by HUT. Younger NMS patients have an increased chronotropic and inotropic activity during rest and OS as well as a decreased vascular reactivity during HUT. Central and peripheral cardiovascular compensatory mechanisms during orthostatic stress may trigger distinct vasovagal responses that vary depending on age. [1]: /embed/graphic-1.gif

Effect of verapamil on QT interval dynamicity

Using measurements of QT/RR slopes with a computerized Holter system, QT interval dynamicity was evaluated in 19 patients with normal structural heart before and 2 months after oral treatment with verapamil prescribed for paroxysmal atrioventricular nodal reentrant tachycardia. Verapamil significantly shortened QT at low heart rates, mainly in the diurnal period, and this characteristic may explain, in part, the previously reported protective effect of verapamil against torsades de pointes.