Association of congenital, diffuse electrical disease in children with normal heart: sick sinus syndrome, intraventricular conduction block, and monomorphic ventricular tachycardia.

INTRODUCTION Rhythm disturbances in children with structurally normal hearts are usually associated with abnormalities in cardiac ion channels. The phenotypic expression of these abnormalities ("channelopathies") includes: long and short QT syndromes, Brugada syndrome, congenital sick sinus syndrome, catecholaminergic polymorphic ventricular tachycardia, Lènegre-Lev disease, and/or different degrees of cardiac conduction disease. METHODS The study group consisted of three male patients with sick sinus syndrome, intraventricular conduction disease, and monomorphic sustained ventricular tachycardia. Clinical data and results of electrocardiography, Holter monitoring, electrophysiology, and echocardiography are described. RESULTS In all patients, the ECG during sinus rhythm showed right bundle branch block and long QT intervals. First-degree AV block was documented in two subjects, and J point elevation in one. A pacemaker was implanted in all cases due to symptomatic bradycardia (sick sinus syndrome). Atrial tachyarryhthmias were observed in two patients. The common characteristic ventricular arrhythmia was a monomorphic sustained ventricular tachycardia, inducible with ventricular stimulation and sensitive to lidocaine. In one patient, radiofrequency catheter ablation was successfully performed. No structural abnormalities were found in echocardiography in the study group. CONCLUSION Common clinical and ECG features suggest a common pathophysiology in this group of patients with congenital severe electrical disease.

A novel C-terminal truncation SCN5A mutation from a patient with sick sinus syndrome, conduction disorder and ventricular tachycardia.

OBJECTIVES Individual mutations in the SCN5A-encoding cardiac sodium channel alpha-subunit cause single cardiac arrhythmia disorders, but a few cause multiple distinct disorders. Here we report a family harboring an SCN5A mutation (L1821fs/10) causing a truncation of the C-terminus with a marked and complex biophysical phenotype and a corresponding variable and complex clinical phenotype with variable penetrance. METHODS AND RESULTS A 12-year-old male with congenital sick sinus syndrome (SSS), cardiac conduction disorder (CCD), and recurrent monomorphic ventricular tachycardia (VT) had mutational analysis that identified a 4 base pair deletion (TCTG) at position 5464-5467 in exon 28 of SCN5A. The mutation was also present in six asymptomatic family members only two of which showed mild ECG phenotypes. The deletion caused a frame-shift mutation (L1821fs/10) with truncation of the C-terminus after 10 missense amino acid substitutions. When expressed in HEK-293 cells for patch-clamp study, the current density of L1821fs/10 was reduced by 90% compared with WT. In addition, gating kinetic analysis showed a 5-mV positive shift in activation, a 12-mV negative shift of inactivation and enhanced intermediate inactivation, all of which would tend to reduce peak and early sodium current. Late sodium current, however, was increased in the mutated channels. CONCLUSIONS The L1821fs/10 mutation causes the most severe disruption of SCN5A structure for a naturally occurring mutation that still produces current. It has a marked loss-of-function and unique phenotype of SSS, CCD and VT with incomplete penetrance.

Radiofrequency catheter ablation of idiopathic ventricular tachycardia originating in the main stem of the pulmonary artery.

We report the case of a patient in whom successful radiofrequency catheter ablation of an idiopathic ventricular tachycardia (VT) originating in the main stem of the pulmonary artery was performed. After successful ablation of the index arrhythmia, which was an idiopathic right ventricular outflow tract VT, a second VT with a different QRS morphology was reproducibly induced. Mapping of the second VT revealed the presence of myocardium approximately 2 cm above the pulmonary valve. Application of radiofrequency energy at this site resulted in termination and noninducibility of this VT. After 6-month follow-up, the patient remained free from VT recurrences.

Frequent ventricular tachycardias: antiarrhythmic drug treatment or catheter ablation?

Antiarrhythmic drugs are used in at least 50% of patients who received an implantable cardioverter defibrillator (ICD). The potential indications for antiarrhythmic drug treatments in patients with an ICD are generally the following: reduction of the number of ventricular tachycardias (VTs) or episodes of ventricular fibrillation and therefore reduction of the number of ICD therapies, most importantly, the number of disabling ICD shocks. Accordingly, the quality of life should be improved and the battery life of the ICD extended. Moreover, antiarrhythmic drugs have the potential to increase the tachycardia cycle length to allow termination of VTs by antitachycardia pacing and reduction of the number of syncopes. In addition, supraventricular arrhythmias can be prevented or their rate controlled. Recently published or reported trials have shown the efficacy of amiodarone, sotalol and azimilide to significantly reduce the number of appropriate and inappropriate ICD shocks in patients with structural heart disease. However, the use of antiarrhythmic drugs may also have adverse effects: an increase in the defibrillation threshold, an excessive increase in the VT cycle length leading to detection failure. In this situation and when antiarrhythmic drugs are ineffective or have to be stopped because of serious side effects, catheter ablation of both monomorphic stable and pleomorphic and/or unstable VTs using modern electroanatomic mapping systems should be considered. The choice of antiarrhythmic drug treatment and the need for catheter ablation in ICD patients with frequent VTs should be individually tailored to specific clinical and electrophysiological features including the frequency, the rate, and the clinical presentation of the ventricular arrhythmia. Although VT mapping and ablation is becoming increasingly practical and efficacious, ablation of VT is mostly done as an adjunctive therapy in patients with structural heart disease and ICD experiencing multiple shocks, because the recurrence and especially the occurrence of "new" VTs after primarily successful ablation with time and disease progression have precluded a widespread use of catheter ablation as primary treatment.

Electrocardiographic pattern as a guide for management and radiofrequency ablation of idiopathic ventricular tachycardia.

BACKGROUND Idiopathic ventricular tachycardia (VT) often originates from the right ventricular outflow tract (RVOT), but foci deep to the endocardium, in the epicardium, or in the left ventricle are not uncommon. Although these extra-RVOT foci can be targeted with ablation, risks involved are higher and success rates lower. Simple electrocardiographic (ECG) criteria allowing (1) discrimination of RVOT foci from extra-RVOT foci and (2) assessment of the chance of success of a right heart ablation procedure are desirable. METHODS Twenty-five consecutive patients referred for radiofrequency (RF) ablation of idiopathic VT or severely symptomatic idiopathic ventricular premature contractions were included. Localization of VT origin and success rates of VT ablation in the RVOT were analyzed according to the ECG pattern. RESULTS The analysis of the R wave in V2 was the strongest single predictor of whether the VT had an RVOT or an extra-RVOT origin. An R wave amplitude < or =30% of the QRS amplitude designated the VT focus in the RVOT with positive and negative predictive values of 95 and 100%, respectively. Analysis of R wave duration in V2 had similar predictive values, whereas the R/S transition zone in precordial leads had slightly lower predictive values. Seventeen of 20 arrhythmias (85%) with an R wave amplitude < or =30% of the QRS amplitude in V2 could be successfully abolished by an exclusively right heart procedure. CONCLUSIONS The analysis of ECG pattern makes it possible to guide the management of patients with idiopathic VT in predicting the arrhythmias that can be safely targeted with RF ablation from the RVOT with high success rates.

Electroanatomic mapping of the endocardium. Implication for catheter ablation of ventricular tachycardia.

The electroanatomic mapping system Carto((R)) with its combination of anatomic and electrophysiologic information has substantially improved our understanding of arrhythmia mechanisms and substrates in patients with ventricular tachycardia (VT) and structural heart disease. Identification of the individual arrhythmogenic substrate and successful ablation guided by the combination of sinus rhythm voltage mapping and conventional electrophysiologic techniques like pace and activation/entrainment mapping are best described for patients with recurrent VT in remote myocardial infarction. In about 75-90% of the patients, the target VT can be ablated with acute success and the patients remain free of any VT recurrence in up to 75%. First results of electroanatomically guided ablation in patients with arrhythmogenic right ventricular dysplasia are promising. Data on ablation of VT in other structural heart diseases are very limited, since the arrhythmogenic substrate is very diffuse, e. g., in dilated cardiomyopathy, or there are only small patient numbers, e. g., for cardiac sarcoidosis or monomorphic VT after repair of congenital heart disease. In this article, the current status of electroanatomically guided endocardial mapping and ablation of VT in patients with structural heart disease is described.

Idiopathic ventricular outflow tract arrhythmias from the great cardiac vein: Challenges and risks of catheter ablation

INTRODUCTION Catheter ablation for idiopathic ventricular arrhythmia is well established but epicardial origin, proximity to coronary arteries, and limited accessibility may complicate ablation from the venous system in particular from the great cardiac vein (GCV). METHODS Between April 2009 and October 2010 14 patients (56 ± 15 years; 9 male) out of a total group of 117 patients with idiopathic outflow tract tachycardias were included undergoing ablation for idiopathic VT or premature ventricular contractions (PVC) originating from GCV. All patients in whom the PVC arose from the GCV were subject to the study. In these patients angiography of the left coronary system was performed with the ablation catheter at the site of earliest activation. RESULTS Successful ablation was performed in 6/14 (43%) and long-term success was achieved in 5/14 (36%) patients. In 4/14 patients (28.6%) ablation was not performed. In another 4 patients (26.7%), ablation did not abolish the PVC/VT. In the majority, the anatomical proximity to the left coronary system prohibited effective RF application. In 3 patients RF application resulted in a coronary spasm with complete regression as revealed in repeat coronary angiography. CONCLUSION A relevant proportion idiopathic VT/PVC can safely be ablated from the GCV without significant permanent coronary artery stenosis after RF application. Our data furthermore demonstrate that damage to the coronary artery system is likely to be transient.

True aneurysm of the peripheral pulmonary artery due to necrotizing giant cell arteritis

Pulmonary artery aneurysm in adults is a rare diagnosis. Most cases described in the literature are either associated with congenital heart disease or pulmonal arterial hypertension, respectively, or are not true aneurysms but rather pseudoaneurysms, which are usually iatrogenic. We present the case of a 68-year old female patient with the incidental finding of a true aneurysm of the right peripheral pulmonary artery with a maximum diameter of 4 cm. With increasing aneurysm diameter over time, the decision for a surgical resection was made. Complete resection of the aneurysm including lower lobe resection was performed. Histopathological examination showed necrotizing giant cell arteritis as the underlying cause. The postoperative course was uneventful and no signs of further disease activity were detected. To our knowledge, this is the first reported case of a pulmonary artery aneurysm caused by giant cell arteritis, whereas it should be noted that the distinction between Takayasu arteritis and giant cell arteritis is not clearly defined. Considering the high mortality associated with aneurysm rupture, surveillance is advocated for small aneurysms, whereas for larger aneurysms and those showing signs of progression in size despite medical therapy or even dissection, surgical intervention should be considered.

Left ventricular torsion abnormalities in septic shock and corrective effect of volume loading: a pilot study

BACKGROUND Ventricular torsion is an important component of cardiac function. The effect of septic shock on left ventricular torsion is not known. Because torsion is influenced by changes in preload, we compared the effect of fluid loading on left ventricular torsion in septic shock with the response in matched healthy control subjects. METHODS We assessed left ventricular torsion parameters using transthoracic echocardiography in 11 patients during early septic shock and in 11 age- and sex-matched healthy volunteers before and after rapid volume loading with 250 mL of a Ringer's lactate solution. RESULTS Peak torsion and peak apical rotation were reduced in septic shock (10.2 ± 5.2° and 5.6 ± 5.4°) compared with healthy volunteers (16.3 ± 4.5° and 9.6 ± 1.5°; P = 0.009 and P = 0.006 respectively). Basal rotation was delayed and diastolic untwisting velocity reached its maximum later during diastole in septic shock patients than in healthy volunteers (104 ± 16% vs 111 ± 14% and 13 ± 5% vs 21 ± 10%; P = 0.03 and P = 0.034, respectively). Fluid challenge increased peak torsion in both groups (septic shock, 10.2 ± 5.3° vs 12.6 ± 3.9°; healthy volunteers, 16.3 ± 4.5° vs 18.1 ± 6°; P = 0.01). Fluid challenge increased left ventricular stroke volume in septic shock patients (P = 0.003). CONCLUSIONS Compared with healthy volunteers, left ventricular torsion is impaired in septic shock patients. Fluid loading attenuates torsion abnormalities in parallel with increasing stroke volume. Reduced torsional motion might constitute a relevant component of septic cardiomyopathy, a notion that merits further testing in larger populations.

Reversal of myocyte hypertrophy by ventricular unloading: cardiac improvement without adrenergic receptor up-regulation and relocalization.

In previous studies, we found that the improved contractile ability of cardiac myocytes from patients who have had left ventricular assist device (LVAD) support was due to a number of beneficial changes, most notably in calcium handling (increased sarcoplasmic reticulum calcium binding and uptake), improved integrity of cell membranes due to phospholipid reconstruction (reduced lysophospholipid content), and an upregulation of adrenoreceptors (increased adrenoreceptor numbers). However, in the case presented here, there was no increase in adrenoreceptor number, which is something that we usually find in core tissue at the time of LVAD removal or organ transplantation; also, there was no homogeneous postassist device receptor distribution. However, the patient was well maintained for 10 months following LVAD implantation, until a donor organ was available, regardless of the lack of adrenoreceptor improvement. We conclude from these studies that cardiac recovery is the result of the initiation of multiple repair mechanisms, and that the lack of expected changes, in this case increased adrenoreceptors, is not always an accurate indicator of anticipated outcome. We suggest that interventions and strategies have to consider multiple, beneficial changes due to unloading and target a number of biochemical and structural areas to produce improvement, even if not all of these improvements occur.