Practical ways to reduce radiation dose for patients and staff during device implantations and electrophysiological procedures.

Despite the advent of non-fluoroscopic technology, fluoroscopy remains the cornerstone of imaging in most interventional electrophysiological procedures, from diagnostic studies over ablation interventions to device implantation. Moreover, many patients receive additional X-ray imaging, such as cardiac computed tomography and others. More and more complex procedures have the risk to increase the radiation exposure, both for the patients and the operators. The professional lifetime attributable excess cancer risk may be around 1 in 100 for the operators, the same as for a patient undergoing repetitive complex procedures. Moreover, recent reports have also hinted at an excess risk of brain tumours among interventional cardiologists. Apart from evaluating the need for and justifying the use of radiation to assist their procedures, physicians have to continuously explore ways to reduce the radiation exposure. After an introduction on how to quantify the radiation exposure and defining its current magnitude in electrophysiology compared with the other sources of radiation, this position paper wants to offer some very practical advice on how to reduce exposure to patients and staff. The text describes how customization of the X-ray system, workflow adaptations, and shielding measures can be implemented in the cath lab. The potential and the pitfalls of different non-fluoroscopic guiding technologies are discussed. Finally, we suggest further improvements that can be implemented by both the physicians and the industry in the future. We are confident that these suggestions are able to reduce patient and operator exposure by more than an order of magnitude, and therefore think that these recommendations are worth reading and implementing by any electrophysiological operator in the field.

Relation of interatrial block to new-onset atrial fibrillation in patients with Chagas cardiomyopathy and implantable cardioverter-defibrillators.

Chagas cardiomyopathy is an endemic disease in Latin America. A significant proportion of patients develop atrial fibrillation (AF), which may result in stroke and increased morbidity or mortality. Interatrial block (IAB) has been associated with the development of AF in different clinical scenarios. The aim of our study was to determine whether IAB can predict new-onset AF in patients with Chagas cardiomyopathy and implantable cardioverter-defibrillators (ICDs). We conducted a retrospective study of patients with Chagas cardiomyopathy and ICDs from 14 centers in Latin America. Demographics, clinical, and device follow-up were collected. Surface electrocardiograms were scanned at 300 dpi and maximized ×8. Semiautomatic calipers were used to determine P-wave onset and offset. Partial IAB was defined as a P wave of >120 ms and advanced IAB as a P wave of >120 ms with biphasic morphology (±) in inferior leads. AF events and ICD therapies were reviewed during follow-up by 2 independent investigators. A total of 80 patients were analyzed. Mean age was 54.6 ± 10.4 years, and 52 (65%) were male. Mean left ventricular ejection fraction was 40 ± 12%. IAB was detected in 15 patients (18.8%), with 8 (10.0%) partial and 7 (8.8%) advanced. During a follow-up of 33 ± 20 months, 11 patients (13.8%) presented with new AF. IAB (partial + advanced) was strongly associated with new AF (p <0.0001) and inappropriate therapy by the ICD (p = 0.014). In conclusion, IAB (partial + advanced) predicted new-onset AF in patients with Chagas cardiomyopathy and ICDs.

Fragmented surface ECG was a poor predictor of appropriate therapies in patients with Chagas' cardiomyopathy and ICD implantation (Fragmented ECG in CHAgas' Cardiomyopathy Study).

BACKGROUND: Main causes of death in chronic Chagas' cardiomyopathy (CChC) are progressive congestive heart failure and sudden cardiac death. Implantable cardioverter defibrillators (ICD) have been proved an effective therapy to prevent sudden death in patients with CChC. Identification of predictors of sudden death remains a challenge. OBJECTIVE: To determine whether surface fragmented ECG (fQRS) helps identifying patients with CChC and ICDs at higher risk of presenting appropriate ICD therapies. METHODS: Multicenter retrospective study. All patients with CChC and ICDs were analyzed. Clinical demographics, surface ECG, and ICD therapies were collected. RESULTS: A total of 98 patients were analyzed. Another four cases were excluded due to pacing dependency. Mean age was 55.5 ± 10.4 years, male gender 65%, heart failure New York Heart Association class I 47% and II 38%. Mean left ventricular ejection fraction (LVEF) 39.6 ± 11.8%. The indication for ICD was secondary prevention in 70% of patients. fQRS was found in 56 patients (59.6%). Location of fragmentation was inferior (57.1%), lateral (35.7%), and anterior (44.6%). Rsr pattern was the more prevalent (57.1%). Predictors of appropriate therapy in the multivariate model were: increased age (P = 0.01), secondary prevention indication (P = 0.01), ventricular pacing >50% of the time (P = 0.004), and LVEF <30% (P = 0.01). The presence of fQRS did not identify patients at higher risk of presenting appropriate therapies delivered by the ICD (P = 0.87); regardless of QRS interval duration. CONCLUSIONS: fQRS is highly prevalent among patients with CChC. It has been found a poor predictor of appropriate therapies delivered by the ICD in this population.

Fragmented QRS as a predictor of arrhythmic events in patients with hypertrophic obstructive cardiomyopathy.

OBJECTIVES: This study aims to determine whether fragmented QRS (fQRS) in the surface electrocardiogram (ECG) at implantable cardioverter defibrillator (ICD) implant can predict arrhythmic events using appropriate therapy delivered by the ICD as a surrogate. BACKGROUND: Hypertrophic obstructive cardiomyopathy (HOCM) is a genetic disorder associated with life-threatening arrhythmias frequently requiring an ICD. Seeking a noninvasive method of risk stratification remains a challenge. METHODS: This paper is a retrospective, multicenter study of patients with HOCM and ICD. Surface 12-lead ECGs were analyzed. Appropriate therapy was validated by a blinded Core Lab. Univariate and multivariate analyses were performed. A p value of <0.05 was considered significant. RESULTS: We included 102 patients from 13 centers. Mean age at implant was 41.16 ± 18.25 years, 52% were male. Mean left ventricular ejection fraction was 61.56 ± 9.46% and two thirds had heart failure according to the New York Heart Association class I. Secondary prophylaxis ICD implantation was the indication for implant in 40.2% of cases. About half received a single-chamber ICD. fQRS was present at the time of diagnosis in 21 and in 54% at ICD implant. At a mean follow-up of 47.8 ± 39.3 months, 41 patients (40.2%) presented with appropriate therapy. In a multivariate logistic regression, predictors of appropriate therapy included fQRS at implant (odds ratio [OR], 16.4; 95% confidence interval [CI], 3.6-74.0; p = 0.0003), history of combined ventricular tachycardia/fibrillation/sudden death (OR, 14.3; 95% CI, 3.2-69.3; p = 0.001) and history of syncope (OR, 5.5; 95% CI, 1.5-20.4; p = 0.009). Ten deaths (9.8%) occurred during the follow-up. fQRS in the lateral location increased the risk of appropriate therapy (p < 0.0001). CONCLUSIONS: fQRS predicts arrhythmic events in patients with HOCM and should be considered in a model of risk stratification.

Taquicardia por reentrada nodal recurrente en paciente con transposición congénita corregida de grandes vasos. Utilización de mapeo no fluoroscópico / Use of non-fluoroscopic mapping in recurrent atrioventricular nodal reentrant tachycardia in a patient with corrected transposition of the great arteries

La complejidad anatómica y la variabilidad en el sistema de conducción en la transposición congénita corregida de los grandes vasos plantean intervenciones con el uso de recursos tecnológicos que faciliten un desenlace favorable. Describimos un caso de ablación de taquicardia por reentrada intranodal en donde el mapeo no fluoroscópico facilitó una intervención compleja.

The anatomy in congenital corrected transposition of the great arteries is complex and the conduction system may experience large degrees of variation. Invasive procedures should be done with the use of the highest possible technological sources to warrant success. We describe here, a patient with recurrent atrioventricular node reentry tachycardia where non-fluoroscopic navigation system helped in a complex ablation.

[Use of non-fluoroscopic mapping in recurrent atrioventricular nodal reentrant tachycardia in a patient with corrected transposition of the great arteries]. / Taquicardia por reentrada nodal recurrente en paciente con transposición congénita corregida de grandes vasos. Utilización de mapeo no fluoroscópico.

The anatomy in congenital corrected transposition of the great arteries is complex and the conduction system may experience large degrees of variation. Invasive procedures should be done with the use of the highest possible technological sources to warrant success. We describe here, a patient with recurrent atrioventricular node reentry tachycardia where non-fluoroscopic navigation system helped in a complex ablation.

A reappraisal on lidocaine-sensitive repetitive, uniform atrial tachycardia.

BACKGROUND: Lidocaine sensitive, repetitive atrial tachycardia is an unusual arrhythmia whose electrophysiologic substrate remains undefined. We aimed to analyze the electropharmacologic characteristics of this arrhythmia with emphasis on its cellular substrate and response to drug challenges. METHODS: We retrospectively analyzed a series of 18 patients from an electrocardiographic and electrophysiologic perspective and the response to pharmacological challenge. RESULTS: There was no evidence of structural heart disease in 12 patients, 4 patients presented with systemic hypertension; one patient had a prior myocardial infarction and one a mitral valve prolapse. The arrhythmia depicted a consistent pattern in nine patients. The first initiating ectopic beat showed a long coupling interval, the cycle length of the second atrial ectopic beat presented the shortest cycle length and a further prolongation was apparent towards the end of the atrial salvos. Conversely, in the other nine cases, the atrial tachycardia cycle length was erratic. The arrhythmia was suppressed by asynchronous atrial pacing at cycle lengths longer than those of the atrial tachycardia. Intravenous lidocaine eliminated the arrhythmia in all patients, but intravenous verapamil suppressed the atrial tachycardia in only two patients while adenosine caused a transient disappearance in 2/8 patients. Only one patient responded to all the three agents. Radiofrequency ablation was successfully performed in 10 patients. CONCLUSIONS: Repetitive uniform atrial tachycardia can be sensitive to lidocaine. In few cases, this rare focal arrhythmia may be also suppressed by adenosine and/or verapamil, which suggests a diversity of electrophysiologic substrates that deserve to be accurately identified.

Brugada phenocopy: new terminology and proposed classification.

Brugada syndrome is a channelopathy characterized on ECG by coved ST-segment elevation (≥2 mm) in the right precordial leads and is associated with an increased risk of malignant ventricular arrhythmias. The term Brugada phenocopy is proposed to describe conditions that induce Brugada-like ECG manifestations in patients without true Brugada syndrome. An extensive review of the literature identified case reports that were classified according to their suspected etiological mechanism. Future directions to learn more about these intriguing cases is discussed.

Permanent pacing in patients with Chagas' disease.

BACKGROUND: Chagas' disease is an endemic disease in most Latin American countries. The cardiomyopathy associated with this condition often requires permanent pacing due to bradycardia. The aim of this study was to compare the indications for pacemaker implantation, intraoperative measurements, and long-term follow-up of patients with Chagas' cardiomyopathy (ChCM) and ischemic cardiomyopathy (ICM) referred for pacemaker implantation. METHODS: Retrospective study including consecutive patients with ChCM (Group 1) and ICM (Group 2), who underwent pacemaker implantation in a single center. RESULTS: We analyzed 360 patients. Patients in Group 1 were younger (66.29 ± 7.01 vs 75.3 ± 7.11 years; P = 0.0001) and more often male (72% vs 60%; P = 0.05). Sinus node dysfunction (SND) was more prevalent in Group 1 (70% vs 52%; P = 0.03). Atrioventricular block was less prevalent in Group 1 (30% vs 48%; P = 0.04). No significant differences were found with respect to left ventricular ejection fraction (54.2 ± 9.1 vs 53.4 ± 8.2%; P = NS) and baseline QRS duration (119 ± 34 vs 108 ± 29 ms; P = NS). Right bundle branch block was more frequent in Group 1 (44% vs 12%; P = 0.0001), and left bundle branch block in Group 2 (6% vs 22%; P = 0.0001). Implantation time was longer in Group 1 (39 ± 19 vs 29 ± 13 minutes; P = 0.001) and was with higher atrial and ventricular pacing thresholds (1.4 ± 0.8 vs 1.0 ± 0.5 V; P = 0.001 and 1.2 ± 0.8 vs 0.6 ± 0.8 V; P = 0.001, respectively). During a follow-up of 42.8 ± 13.6 months, Group 1 had a higher incidence of new atrial fibrillation (34% vs 25.5%; P = 0.001), and there was a nonsignificant trend toward more displacements of the ventricular lead (6% vs 3.5%; P = 0.3). There were no deaths during the follow-up. CONCLUSIONS: ChCM patients receiving pacemakers are younger and more frequently have SND compared to those with ICM. Pacemaker implant is longer in patients with ChCM disease and is with higher pacing thresholds. The incidence of new atrial fibrillation during the follow-up is significantly higher in patients with ChCM.

"Benign" early repolarization versus malignant early abnormalities: clinical-electrocardiographic distinction and genetic basis.

In the great majority of cases the ECG pattern of early repolarization (ERP) is a benign phenomenon observed predominantly in teenagers, young adults, male athletes and the black race. The universally accepted criterion for its diagnosis is the presence, in at least two adjoining leads, of ≥ 1 mm or 0.1 mV ST segment elevation. In benign ERP reciprocal ST segment changes are possible only in lead aVR. In contrast, reciprocal ST segment changes can be observed in several leads in idiopathic ventricular fibrillation (IVF) and acute coronary syndrome. In benign ERP the ST segment and T wave patterns have a relative temporal stability. IVF is an entity with low prevalence, possibly familiar, and characterized by the occurrence of VF events in a young person. More frequently this occurs in male subjects without structural heart disease and with otherwise with normal ECG even using high right accessory leads and/or after ajmaline injection. Several clinical entities cause ST segment elevation include asthenic habitus, acute pericarditis, ST segment elevation myocardial infarction, Brugada syndrome, congenital short QT syndrome, and idiopathic VF. In these circumstances clinical and ECG data are most important for differential diagnosis. In IVF the modifications could be dramatic and predominantly at night during vagotonic predominance when J waves > 2 mm in amplitude. The ST/T abnormalities are dynamic, inconstant, and reversed with isoproterenol. Convex upward J waves, with horizontal/descending ST segments or "lambda-wave" ST shape are suggestive of IVF with early repolarization abnormalities. Premature ventricular contractions with very short coupling and "R on T" phenomenon are characteristics with two pattern: When originate from right ventricular outflow tract left bundle branch block morphology and from peripheral Purkinje network, left bundle branch block pattern. The inherited-familial forms are not frequent in IVF; however mutations were identified in the genes KCNJ8, DPP6, SCN5A, SCN3B, CACNA1C, CACNB2, and CACNA2D1. The management of IVF has class I indication for ICD implantation. Ablation therapy is considered additional to ICD implantation in those patients with repetitive ventricular arrhythmia. Quinidine is a highly efficient drug that prevents recurrence.

Bidirectional ventricular tachycardia: a hallmark of catecholaminergic polymorphic ventricular tachycardia.

Catecholaminergic polymorphic ventricular tachycardia is a familial cardiac arrhythmia that is related to RYR2 or CASQ2 gene mutation. It occurs in patients with structurally normal heart and causes exercise-emotion triggered syncope and sudden cardiac death. We present a 13 year-old girl with recurrent episodes of exercise-related syncope and prior history of sudden death in a first degree relative.

Resultados del uso de marcapasos definitivo en pacientes con cardiopatía chagásica y con enfermedad coronaria / Results of the use of definitive pacemakers in patients with chagasic cardiomyopathy and in patients with coronary artery disease

En la mayoría de los países de Latinoamérica, la enfermedad de Chagas es endémica y la miocardiopatía isquémica es la primera causa de afección cardíaca. Ambas entidades conviven generando un modelo biológico y epidemiológico único, y al ser enfermedades de evolución crónica, por diversos motivos pueden requerir el implante de un marcapasos definitivo. El objetivo del presente trabajo fue comparar los motivos de implante, detalles técnicos y evolución de pacientes referidos para tratamiento con marcapasos definitivo y portadores de miocardiopatía chagásica o miocardiopatía isquémica.

Resultados del uso de marcapasos definitivo en pacientes con cardiopatía chagásica y con enfermedad coronaria / Results of the use of definitive pacemakers in patients with chagasic cardiomyopathy and in patients with coronary artery disease

En la mayoría de los países de Latinoamérica, la enfermedad de Chagas es endémica y la miocardiopatía isquémica es la primera causa de afección cardíaca. Ambas entidades conviven generando un modelo biológico y epidemiológico único, y al ser enfermedades de evolución crónica, por diversos motivos pueden requerir el implante de un marcapasos definitivo. El objetivo del presente trabajo fue comparar los motivos de implante, detalles técnicos y evolución de pacientes referidos para tratamiento con marcapasos definitivo y portadores de miocardiopatía chagásica o miocardiopatía isquémica. (AU)