Crazy accessory pathway- going round the bend!

A 15-year-old boy with manifest preexcitation and recurrent palpitations had undergone an unsuccessful ablation procedure elsewhere and was subsequently referred to us. The ECG suggested a left free wall pathway but there was a pattern break in lead V2. This helped localise the accessory pathway to the summit region and achieve success.

For neonatal ECG screening there is no reason to relinquish old Bazett's correction.

Aims: There is an almost endless controversy regarding the choice of the QT correction formula to be used in electrocardiograms (ECG) in neonates for screening for long QT syndrome (LQTS). We compared the performance of four commonly used formulae and a new formula derived from neonates. Methods and results: From a cohort of 44 596 healthy neonates prospectively studied in Italy between 2001 and 2006, 5000 ECGs including 17 with LQTS-causing mutation identified by genotyping were studied using four QT correction formulae [Bazett's (QTcB), Fridericia's (QTcF), Framingham (QTcL), and Hodges (QTcH)]. A neonate-specific exponential correction (QTcNeo) was derived using 2500 randomly selected ECGs and validated for accuracy in the remaining 2500 ECGs. Digital ECGs were recorded between the 15th and 25th day of life; QT interval was measured manually in leads II, V5, and V6. To assess the ability to provide heart rate (HR) independent QT correction, regression analysis of the QTc-HR plots for all 5000 ECGs with each correction formula was done. QTcB provided the most HR independent correction with a slope closest to zero (slope +0.086 ms/b.p.m.) followed by QTcF (slope -0.308 ms/b.p.m.), QTcL (slope -0.364 ms/b.p.m.), and QTcH (slope +0.962 ms/b.p.m.). The QTc-HR slope of QTcNeo (QT/RR0.467) was similar to QTcB. The ability to correctly identify neonates with LQTS was best with QTcB, QTcF, and QTcNeo (comparable areas under the receiver operating characteristic curves) with positive predictive value of 39-40% and sensitivity of 100%. Cut-off values were 460 ms for QTcB, 394 ms for QTcF, and 446 ms for QTcNeo. Conclusions: The Bazett's correction provides an effective HR independent QT correction and also accurately identifies the neonates affected by LQTS. It can be used with confidence in neonates, although other methods could also be used with appropriate cut-offs.

A Study of Prehospital Delay Patterns in Acute Myocardial Infarction in an Urban Tertiary Care Institute in Mumbai.

OBJECTIVE: There is now increasing awareness about the need for early diagnosis in patients presenting with chest pain. Pre-hospital delay remains a major hurdle in the institution of early reperfusion therapy, which is crucial in salvaging 'at-risk' myocardium and reducing adverse cardiovascular events following ST elevation myocardial infarction (STEMI). This study aims to determine the incidence and the determinants of delayed presentation STEMI and the potential impact of such delay on adverse cardiovascular outcomes. METHODS: We prospectively evaluated all patients who were admitted in the emergency department of our hospital with STEMI from March 2014 to February 2016. Data was collected sequentially at the time of admission, discharge and during follow-up. Patients were evaluated with serial ECGs, continuous ECG monitoring and echocardiography. RESULTS: Out of 1386 patients with STEMI, delayed presentation was seen in 1148 (> 2 hrs) and 805 (> 4 hrs) patients. The duration from onset of symptoms to the presentation in the emergency room (pre-hospital delay) was 228 ± 341minutes.The door to needle time was 34 ± 24 minutes. The major factors for pre-hospital delay were misinterpretation of symptoms (45%) and transportation problems (27%). CONCLUSIONS: The problem of pre-hospital delay continues to remain a major hurdle in initiating timely reperfusion therapy in patients with acute STEMI. Lack of awareness and poor transportation facilities are the major contributors. It should be the goal of STEMI care programmes of the future to make a concerted effort to addressing these factors, in order to optimize the benefit of reperfusion therapy for this high risk group of patients.

'Hibernating' accessory pathway.

A 13-year-old boy presented with recurrent narrow QRS tachycardia from which he had been suffering for one year. An electrophysiology study revealed a concealed left lateral accessory pathway with inducible orthodromic atrioventricular re-entry tachycardia using the same pathway. The accessory pathway was ablated in January 2004. After the ablation, atrioventricular block was demonstrated (with adenosine), as was ventriculo-atrial block, and the patient had paroxysmal tachycardia one month later. This time, however, the electrocardiogram in sinus rhythm showed a negative delta wave in V1, suggestive of a right-sided accessory pathway. Another electrophysiology study showed no conduction across the left accessory pathway found earlier. The right accessory pathway, which had 'emerged' after the ablation, had an antegrade effective refractory period of 440 msec and a retrograde effective refractory period of <250 msec. Orthodromic atrioventricular re-entry tachycardia using this accessory pathway was easily inducible. The tricuspid annulus was mapped and the second accessory pathway was localized to the right anterolateral region. This was ablated successfully. This is a unique instance of a symptomatic 'hibernating' accessory pathway emerging in adolescence.

Arrhythmias Seen in Baseline 24-Hour Holter ECG Recordings in Healthy Normal Volunteers During Phase 1 Clinical Trials.

Regulatory agencies encourage sponsors to submit 24-hour ambulatory ECG data for assessing cardiac safety of new drugs, and some arrhythmias, hitherto considered rare, have been observed in some early-phase studies. Interpretation of these observations is difficult given the dearth of published data on the prevalence of cardiac arrhythmias seen during 24-hour continuous ECG monitoring in healthy volunteers (HV) from clinical trials. We analyzed drug-free ambulatory ECG recordings from 1273 HV (1000 males, 273 females; age 18-65 years) from 22 phase 1 studies that were analyzed in a core ECG laboratory; all subjects had normal screening ECGs. Supraventricular arrhythmias such as supraventricular premature complexes were observed in 60.8% of healthy volunteers, supraventricular tachycardia in 2.2%, and atrial fibrillation in 0.1%. Ventricular arrhythmias included premature ventricular complexes (PVCs) in 43.4%, >200 PVCs per 24 hours in 3.3%, multifocal PVCs in 5.3%, nonsustained ventricular tachycardia in 0.7%, and accelerated idioventricular rhythm in 0.3%. Bradyarrhythmias included sinus pause >3 seconds in 0.3%, and second-degree AV block in 2.4%. Complete heart block and torsades de pointes were not seen in any subject. Based on the observed incidence, we estimated the maximum number of healthy subjects in whom these arrhythmias may be seen as a matter of chance in studies with smaller sample sizes if the study drug has no arrhythmogenic effect. Our results and these estimates could help interpret whether cardiac arrhythmias observed in early-phase studies are due to chance or possibly are a drug effect.

Incessant fascicular VT presenting as cardiogenic shock with multi-organ dysfunction syndrome.

We report a rare clinical presentation of incessant idiopathic fascicular ventricular tachycardia (FVT), presenting as multi-organ dysfunction (MOD) syndrome with cardiogenic shock. Our patient was a 19-year-old male who presented with slowly progressive dyspnea from New York Heart Association (NYHA) II to NYHA IV at the time of presentation, palpitations, and dilated cardiomyopathy due to drug-refractory FVT. The patient was in cardiogenic shock with raised central venous pressures and required inotropic support for maintaining systolic blood pressure above 90 mmHg. The MOD was seen in the form of deranged liver and kidney parameters. Echocardiography showed a dilated left ventricle (LV, 58 mm at end-diastole, 52 mm at end-systole) and decreased ejection fraction (20%). Electrocardiography showed a wide-QRS tachycardia (QRS 140 ms, cycle length 440 ms), with RsR' in lead V1 and a QRS axis of -60°. After stabilization with ventilation, inotropic support, and cautious use of diuretics, an electrophysiologic study was performed. A Purkinje potential with early local ventricular activation was recorded from the LV inferoseptal region. The tachycardia was ablated at this site with radiofrequency (RF) energy (40 W for 35 sec). Over a 3-month follow-up, the patient remained asymptomatic and the LV size and function returned to normal. .

Radiofrequency ablation of incessant orthodromic tachycardia in a young child with a univentricular heart.

The incidence of supraventricular tachycardia is high in infants and children with congenital heart disease. We report a case of incessant orthodromic tachycardia in a child with a univentricular heart, which was successfully treated with radiofrequency ablation.

Catheter ablation of atrial tachycardia using a real-time position management mapping system.

Catheter ablation for atrial tachycardia is limited by its low success rate and prolonged procedure time because of difficulties in mapping the site of the tachycardia. A new three-dimensional mapping system, the Cardiac Pathways mapping system, using an ultrasound transducer, has recently become available. We report a case of focal atrial tachycardia ablation with this system.

'Rescue' radiofrequency ablation for atrial tachycardia presenting as cardiomyopathy in pregnancy.

A young primiparous lady presented with drug-refractory atrial tachycardia which had led to cardiomyopathy. Three attempts with electrical cardioversion were also unsuccessful. She was rescued by radiofrequency ablation.

Radiofrequency ablation of incessant atrial tachycardia in an infant.

Ectopic automatic atrial tachycardia, an uncommon type of supraventricular tachycardia in children and adults, has been reported to be resistant to medical therapy unlike reentrant supraventricular tachycardia. We report a case of incessant atrial tachycardia in an infant, which was successfully treated with radiofrequency catheter ablation.

Incessant atrial flutter after device closure of atrial septal defect: successful radio frequency ablation.

A four-month-old baby presented with failure to thrive and congestive cardiac failure precipitated by a lower respiratory tract infection. He was found to have a large ostium secundum atrial septal defect measuring 18 mm. This was successfully closed percutaneously by a device (Blockaid). A month after the device deployment the child developed typical atrial flutter. Despite rate control drugs the ventricular rate remained 140/min over the next several months. In view of the incessant atrial flutter with fast ventricular response, the child underwent radiofrequency ablation at the age of 2 years. An isthmus block was created which successfully terminated the tachycardia.

Atriofascicular pathways: Where to ablate?

BACKGROUND: Atriofascicular accessory pathway (AP), often referred to as Mahaim pathway, is an uncommon form of preexcitation. The usual target for ablation is at the site of a high-frequency potential along the tricuspid annulus (TA). We present our observations in mapping and ablation of 29 patients with atriofascicular APs. METHODS AND RESULTS: Twenty-nine consecutive patients who underwent radiofrequency ablation (RFA) for atriofascicular pathways comprised the series. Demographic factors, clinical features of the tachycardia, ablation site, and results were analyzed. The mean age was 19 +/- 8 years; 15 were men. Three patients had Ebstein's anomaly of the tricuspid valve. Four patients had an additional AP and two patients had concomitant typical atrioventricular nodal reentrant tachycardia. RFA was successful in 28 patients (97%); repeat ablation was required in two patients. The site of successful ablation was on the TA at the site of a sharp, high frequency potential in 15 patients (52%). In the remaining 14 patients, a potential was not found along the TA, and ablation was targeted at the ventricular insertion of the AP into the distal right bundle. At the successful ventricular ablation site, local ventricular activation preceded the surface electrocardiogram by 20 +/- 6 ms. Eight of the 14 patients (57%) undergoing ablation in the ventricle, developed right bundle branch block (RBBB). One patient who underwent successful ablation along the TA also manifested RBBB after ablation; however, this patient had Ebstein's anomaly and preexcitation had completely masked the RBBB. The mean procedure and fluoroscopy time was 150 +/- 32 and 35 +/- 12 minutes, respectively. CONCLUSIONS: In atriofascicular pathways, an AP potential was found along the TA in only 52% of patients. Ablation at the ventricular insertion site often resulted in RBBB (57%), but the AP was also successfully ablated.

Adenosine induced ventricular fibrillation in Wolff-Parkinson-White syndrome.

VF was observed in four patients (group A) with preexcited AF presenting to the emergency department who had been given 12 mg of adenosine. These patients were resuscitated and underwent electrophysiological study and catheter ablation of the accessory pathway (AP). In a control (group B) of five patients with manifest AP, sustained AF was induced by rapid atrial pacing during electrophysiological study and 12 mg of adenosine was administered. The ECG and electrophysiologic features in the two groups were compared. All patients had a single manifest AP. In group A, three patients had a left free-wall AP and one patient had a posteroseptal AP, while in the control group all had left free-wall APs. The antegrade AP effective refractory period (ERP) in groups A and B was 227 +/- 29 and 289 +/- 37 ms, respectively (P < 0.05). The atrial ERP was 210 +/- 17 versus 219 +/- 21 ms, respectively, in groups A and B (P > 0.05). The shortest R-R interval during AF in group A was 246 +/- 51 ms and 301 +/- 60 ms in group B (P value < 0.05). After adenosine, no patient in group B developed VF. Adenosine may cause VF when administered during preexcited AF. This phenomenon is seen in patients having APs with short refractory periods.

Primary radiofrequency ablation for incessant idiopathic ventricular tachycardia.

Fascicular VT and RVOT tachycardia are sometimes difficult to induce by programmed electrical stimulation (PES), despite pharmacologic provocation. In such instances, catheter mapping is hampered and efficacy of catheter ablation is difficult to judge. The study included nine patients who presented with incessant idiopathic VT and were directly taken to the electrophysiological laboratory for RF ablation. During the same period, elective ablation was performed on 108 patients with idiopathic VT. The success rate, procedural and fluoroscopy times number of energies, and the peak temperature were evaluated and compared. Of the nine patients, seven had incessant fascicular VT and two had RVOT tachycardia. The mean VT cycle length was 356 +/- 32 ms and the earliest endocardial activation time during VT was 23.6 +/- 6 ms relative to surface QRS complexes. A fascicular potential was not seen in three of the seven patients with fascicular VT. The mean procedural time was 71 +/- 32 minutes and 144 +/- 40 minutes (P = 0.023) while the fluoroscopy time was 14.6 +/- 4.6 minutes and 30 +/- 16 minutes (P < 0.001), respectively, in the primary ablation and elective groups. The total number of RF energies delivered was 2.0 +/- 1.3 versus 7.4 +/- 5.6 (P = 0.07), respectively. The significantly increased procedural time during elective ablation was largely due to time spent in fascicular VT induction. All patients in the primary ablation group were successfully ablated and none had a recurrence. Primary ablation is a safe and effective option in patients with incessant idiopathic VT. Moreover, in fascicular VT, it is superior to elective ablation in terms of success, fluoroscopy and procedural times.