Widespread Electroanatomic Alterations of Right Cardiac Chambers in Patients with Myotonic Dystrophy Type 1

INTRODUCTION

Conduction disturbances and arrhythmias characterize the cardiac feature of myotonic dystrophy type 1 (MD1); a myocardial involvement has been suggested as part of the cardiac disease. The aim of our study was to investigate the underlying myocardial alterations using electroanatomic mapping (CARTO) and their possible correlation with genetic and neurological findings.

METHODS AND RESULTS

Right atrial and ventricular CARTO maps were obtained in 13 MD1 patients. Thirteen age-matched patients with paroxysmal supraventricular tachycardia and normal heart served as controls. Unipolar voltage (UNI-v), bipolar voltage (BI-v) amplitudes, bipolar potential duration (Bi-dur), and atrial propagation time (A-pt) were measured. UNI-v and BI-v in interatrial septum, anterolateral atrial wall, and right ventricle outflow tract were lower in MD1 patients than controls (P < 0.001). Bi-dur and A-pt were longer in MD1 patients than controls (P < 0.001, P = 0.046, respectively). A significant relationship was documented between CTG triplets and the percentage of Bi-v <0.5 mV in the atrial anteroseptal region (r = 0.6, P = 0.02).

CONCLUSIONS

Altered electroanatomic patterns are present in the right cardiac chambers in MD1 patients. Widespread myocardial alterations, not necessarily limited to the conduction system, may support the presence of a cardiac myopathy as part of the disease.

Rate-control or rhythm-control: where do we stand?

Atrial fibrillation is the most common sustained rhythm disturbance and its prevalence is increasing worldwide due to the progressive aging of the population. Current guidelines clearly depict the gold standard management of acute symptomatic atrial fibrillation but the best-long term approach for first or recurrent atrial fibrillation is still debated with regard to quality of life, risk of new hospitalizations, and possible disabling complications, such as thromboembolic stroke, major bleeds and death. Some authors propose that regaining sinus rhythm in all cases, thus re-establishing a physiologic cardiac function not requiring a prolonged antithrombotic therapy, avoids the threat of intracranial or extracranial haemorrhages due to Vitamin K antagonists or aspirin. On the contrary, advocates of a rate control approach with an accurate antithrombotic prophylaxis propose that such a strategy may avoid the risk of cardiovascular and non cardiovascular side effects related to antiarrhythmic drugs. This review aims to explore the state of our knowledge in order to summarize evidences and issues that need to be furthermore clarified.

Rate versus rhythm control in the management of patients with atrial fibrillation

The management of patients with atrial fibrillation involves three main areas: anticoagulation, rate control and rhythm control. Importantly, these are not mutually exclusive of each other. Anticoagulation is necessary for patients who are at a high risk of stroke; for example, those who are older than 75 years, or those who have hypertension, severe left ventricular dysfunction, previous cerebrovascular events, or diabetes. It is now clear that patients who are at a high risk of stroke require long-term anticoagulation with warfarin regardless of whether a rate-control or rhythm-control strategy is chosen. One possible exception might be patients who are apparently cured with catheter ablation. Several published trials comparing rate-control and rhythm-control strategies for the treatment of patients with atrial fibrillation have shown no difference in mortality between these approaches. The patients enrolled in these studies were typically over 65 years of age. Data comparing rate and rhythm strategies in patients who are younger than 60 years of age are limited. For more elderly patients, it seems reasonable to consider rate control as a primary treatment option and to reserve rhythm control for those who do not respond to rate control. For younger patients, we prefer to start with a rhythm-control approach and to reserve rate-control approaches for patients in whom antiarrhythmic drugs, ablation, or both, do not ameliorate the symptoms.

Safety and Feasibility of Coronary Sinus Left Ventricular Leads Extraction: A Preliminary Report

BACKGROUND

transvenous positioning of the left ventricular (LV) lead in a branch of the coronary sinus (CS) is generally the preferred implantation technique in biventricular pacing. Very few data are reported about removal of LV pacing leads positioned in a CS branch. Aim of the study was to describe our experience with percutaneous extraction of LV pacing leads in order to evaluate feasibility and safety of this procedure.

METHODS

we enrolled 392 patients who underwent a biventricular pacing implant. The indication for catheter removal was considered in case of definite diagnosis of infection and in some cases of lead dislodgement or diaphragmatic stimulation. LV lead extraction was first attempted by manual traction; in case of failure a locking stylet or locking stylet plus radiofrequency could be used.

RESULTS

twelve of 392 patients implanted needed LV lead removal. The leads had been in place for 13.9 +/- 11.7 months. Extraction was indicated in 5 of them for LV lead dislodgement or diaphragmatic stimulation, and in 7 patients for lead infection. In all cases manual traction succeeded to remove the LV lead. In 7 cases of infection, the right atrial and ventricular leads were removed. The mean total procedure time was 69 +/- 22 min. No complications were observed.

CONCLUSIONS

our study suggests that CS leads could be easily and safely removed without any complication, also when placed in a CS branch, at least for relatively young catheters.

A randomized evaluation of different approaches to coronary sinus venography during biventricular pacemaker implants

AIM

Biventricular implantation procedures require contrast venography of the coronary sinus. The aim of our study was to evaluate the efficacy and safety of contrast venography obtained by direct manual contrast injection into the guiding catheter, compared with venography obtained after occlusion of the coronary sinus by a Swan-Ganz catheter.

METHODS

Eighty-three patients were randomly assigned to direct or occlusive venography technique. The primary endpoint was complication rate. The secondary endpoints were rate of and time required for an adequate venography, total dose of contrast medium and total procedure time.

RESULTS

Four dissections of the coronary sinus were observed with the occlusive venography technique group while no complications were observed with the direct venography technique group (p=0.04). Rate of adequate venography was similar in the two groups (p=NS). The time needed for coronary sinus venography and the total dose of contrast medium was significantly lower in the direct venography technique group compared with the alternative (p<0.0001 and p=0.003, respectively); the total procedure time was not significantly different between the two groups (p=NS).

CONCLUSIONS

The direct venography technique shows a significantly lower incidence of complications and should be considered to be the first line approach to coronary sinus venography during biventricular pacemaker implantation.

Prolonged Asystolia in a Young Athlete: A Case of Sinus Arrest During REM Sleep

A young asymptomatic male athlete came to our laboratory to be enrolled in a research protocol on physical fatigue. Routine clinical and cardiological evaluations including echocardiogram were in the normal range. Several consecutive cardiopulmonary tests showed a fairly good tolerance to exercise, with no symptoms even when the effort was abruptly arrested. On the other hand, Holter ECG recordings showed long nocturnal sinus pauses. As he was absolutely asymptomatic and free from any structural heart disease, he underwent a follow-up with repeated Holter monitorings for one year. During this period he decided on his own to stop practising sports; in spite of this sharp reduction in his overall physical activity, consecutive Holter monitorings showed that the sinus pauses were progressively increasing in duration (up to 9.2 seconds). With the hypothesis of a malignant vagotonia, he underwent a tilt test; however, we could not elicit any pauses or symptoms. The pauses grew longer over time; a endocavitary electrophysiologic test was performed, which showed no evidence of disease. To rule out the hypothesis of a sleep apnoea syndrome, he also underwent a polysomnography, including EEG, eye movement electromyography, arterial blood oxygen saturation and thoracic impedance: no alterations were detected with the exception of the sinus pauses, which appeared to be strictly linked to REM sleep, as suggested by the concurrent increase in rapid eye movements and desynchronized EEG. We hence made a diagnosis of sinus arrest during REM sleep (SAdRS), a very uncommon disease belonging to the parasomnias. Pauses were then quantified for one month by implanting a ECG loop recorder. As the patient became more and more upset and worried, and the pauses increased to nearly 12 seconds, we decided to implant a pacemaker, which is the only therapeutic option established in the literature for patients with SAdRS.

A Randomized Comparison of Alternative Techniques to Achieve Coronary Sinus Cannulation During Biventricular Implantation Procedures

INTRODUCTION

Biventricular pacing system implantation is a time-consuming and challenging procedure. A critical step in biventricular pacemaker implantation is coronary sinus (CS) cannulation. CS cannulation can be achieved either using dedicated guiding catheters (guiding catheter alone positioning strategy, GCA) or with the aid of an electrophysiology catheter advanced inside the guiding catheter (electrophysiology catheter aided positioning strategy, EPA).

AIM OF THE STUDY

To evaluate whether the EPA technique is useful for reducing CS cannulation time compared to a conventional GCA technique.

METHODS

Thirty-four consecutive patients were randomly assigned to the GCA (18 patients) or EPA (16 patients) CS cannulation strategy.

RESULTS

Time to successful catheterization of CS was 5.0 +/- 2.4 min in the EPA group versus 10.1 +/- 5.4 min in the GCA group p = 0.004. Fluoroscopy time was 4.6 +/- 2.3 min in the EPA group versus 9.2 +/- 4.9 min in the GCA group p = 0.004. Total contrast dye volume to search and engage the CS ostium was 0.0 ml in the EPA group versus 14.3 +/- 3.4 ml in the GCA group p < 0.001.

CONCLUSIONS

Cannulation of CS with the adjunct of an electrophysiology catheter to dedicated delivery systems significantly reduces procedural time, fluoroscopy time and contrast dye volume compared to a conventional strategy.

Cardiac features of Emery–Dreifuss muscular dystrophy caused by lamin A/C gene mutations

AIMS

Retrospective studies have identified a mutation in the lamin A/C (LMNA) gene in patients selected on the basis of a phenotype characterized by dilated cardiomyopathy, atrioventricular conduction disturbances and sudden death. However, the features of cardiac abnormalities in patients with an initial diagnosis of Emery-Dreifuss muscular dystrophy (EDMD) are poorly known. Aim of the present study was to investigate the spectrum of cardiac disease in patients with an initial diagnosis of EDMD caused by a mutation in the LMNA gene.

METHODS AND RESULTS

Ten consecutive patients with EDMD and a LMNA gene mutation were evaluated with structured medical interview, physical examination, ECG, echocardiogram and 24-h Holter monitoring. Electrophysiological testing and cardiac catheterization were performed if a class 1 or 2 American Heart Association guidelines indication was present. Cardiac disease was found in eight of 10 patients and consisted in the variable combination of supraventricular arrhythmias, disorders of atrioventricular conduction, ventricular arrhythmias, dilated cardiomyopathy, non-dilated cardiomyopathy, restrictive cardiomyopathy and sudden death despite pacemaker implant.

CONCLUSIONS

Cardiac disease is common in patients with an initial diagnosis of EDMD caused by a mutation in the LMNA gene and consists of arrhythmias, disorders of atrioventricular conduction, cardiomyopathies and sudden death despite pacemaker implant.

Clinical, electrocardiographic and electrophysiological predictors of atrial fibrillation development in different cardiac substrates

We performed a review of the current literature in order to evaluate clinical, electrocardiographic and electrophysiologic parameters predictive of atrial fibrillation development. Clinical parameters were obtained from two large observational studies (the Framingham heart study and the Cardiovascular health study). Different laboratoristic predictors were also reviewed: ECG-derived predictors, among which we separately evaluated those derived from the 12-lead surface ECG and those derived from the signal averaged P-wave, and other electrophysiologic predictors as atrial monophasic action potential analysis. We also evaluated the clinical value of these different parameters in atrial fibrillation in patients with no overt structural heart disease and in the most common clinical conditions known to be related to atrial fibrillation development such as hypertension, heart failure, cardiovascular surgery.

Late occurrence of heart block after radiofrequency catheter ablation of the septal region: clinical follow-up and outcome

INTRODUCTION

There are few data regarding the occurrence of delayed heart block at least 24 hours after radiofrequency catheter ablation (RFCA) of AV nodal reentry or posteroseptal accessory pathways (APs). We investigated the late occurrence of heart block in this population, the clinical outcome, and whether findings at electrophysiologic study could have predicted its development.

METHODS AND RESULTS

Two of 418 patients with AV nodal reentry undergoing RFCA using a posterior approach and 1 of 54 patients with RFCA of a posteroseptal AP developed late heart block. Anterograde and retrograde AV nodal conduction before and after RFCA were normal. Patients received 12, 15, and 32 RFCA lesions, respectively, using a mean maximum power of 44 W. The RFCA sites were the posterior septum for posteroseptal AP and the posterior and mid-septum for patients with AV nodal reentry, with no His electrogram ever recorded at the ablation site. During RFCA, junctional tachycardia occurred with 1:1 VA conduction in the patient with a posteroseptal AP, but occasional intermittent single retrograde blocked complexes were present in both patients with AV nodal reentry. No rapid junctional tachycardia or >1 consecutive retrograde blocked complex was ever observed during RFCA. Persistent high-degree AV block with junctional escape developed 2 days after RFCA in the posteroseptal AP patient. A permanent pacemaker was implanted, and normal conduction was noted 16 days after RFCA. Both patients with AV nodal reentry complained of fatigue, mainly on exertion, 3 to 4 days after RFCA, and ECG-documented exercise-induced variable AV block was obtained. Because heart block resolved in our initial patient, a prolonged monitoring period was allowed. Symptoms disappeared at 13 and 8 days, and a follow-up treadmill test showed normal PR interval and no heart block. No recurrence of heart block has been seen in any of these three patients.

CONCLUSION

Late unexpected heart block after RFCA of AV nodal reentry and posteroseptal AP is rare, often resolves uneventfully in 1 to 2 weeks, and no specific electrophysiologic findings predicted its occurrence. Prolonged clinical observation is preferable to immediate pacemaker implantation in such patients.

Implantable defibrillator event rates in patients with unexplained syncope and inducible sustained ventricular tachyarrhythmias: a comparison with patients known to have sustained ventricular tachycardia

OBJECTIVES

To assess the clinical significance of inducible ventricular tachyarrhythmias among patients with unexplained syncope.

BACKGROUND

Induction of sustained ventricular arrhythmias at electrophysiology study in patients with unexplained syncope and structural heart disease is usually assigned diagnostic significance. However, the true frequency of subsequent spontaneous ventricular tachyarrhythmias in the absence of antiarrhythmic medications is unknown.

METHODS

In a retrospective case-control study, the incidence of implantable cardiac defibrillator (ICD) therapies for sustained ventricular arrhythmias among patients with unexplained syncope or near syncope (syncope group, n = 22) was compared with that of a control group of patients (n = 32) with clinically documented sustained ventricular tachycardia (VT). Sustained ventricular arrhythmias were inducible in both groups and neither group received antiarrhythmic medications. All ICDs had stored electrograms or RR intervals. Clinical variables were similar between groups except that congestive cardiac failure was more common in the syncope group.

RESULTS

Kaplan-Meier analysis of the time to first appropriate ICD therapy for syncope and control groups produced overlapping curves (p = 0.9), with 57 +/- 11% and 50 +/- 9%, respectively, receiving ICD therapy by one year. In both groups, the induced arrhythmia was significantly faster than spontaneous arrhythmias, but the cycle lengths of induced and spontaneous arrhythmias were positively correlated (R = 0.6, p < 0.0001). During follow-up, three cardiac transplantations and seven deaths occurred in the syncope group, and two transplantations and five deaths occurred in the control group (36-month survival without transplant 52 +/- 11% and 83 +/- 7%, respectively, p = 0.03).

CONCLUSIONS

In patients with unexplained syncope, structural heart disease and inducible sustained ventricular arrhythmias, spontaneous sustained ventricular arrhythmias occur commonly and at a similar rate to patients with documented sustained VT. Thus, electrophysiologic testing in unexplained syncope can identify those at risk of potentially life-threatening tachyarrhythmias, and aggressive treatment of these patients is warranted.

Electrograms for identification of the atrial ablation site during catheter ablation of accessory pathways

BACKGROUND

Catheter ablation of accessory pathways using radiofrequency current has been shown to be effective in patients with Wolff-Parkinson-White syndrome, by using either the ventricular or atrial approach. However, the unipolar electrogram criteria for identifying a successful ablation at the atrial site are not well established.

METHODS AND RESULTS

One hundred patients with Wolff-Parkinson-White were treated by delivering radiofrequency energy at the atrial site. Attempts were considered successful when ablation (disappearance of the delta wave) occurred in < 10 seconds. In eight patients with concealed pathway, the accessory pathway location was obtained by measuring the shortest V-A interval either during ventricular pacing or spontaneous or induced reciprocating tachycardia. In 92 patients both atrioventricular valve annuli were mapped during sinus rhythm, in order to identify the accessory pathway (K) potential before starting the ablation procedure. When a stable filtered (30-250 Hz) "unipolar" electrogram was recorded, the following time intervals were measured: (1) from the onset of the atrial to the onset of the K potential (A-K); (2) from the onset of the delta wave to the onset of the K potential (delta-K); and (3) from the onset of the K potential to the onset of the ventricular deflection (K-V). During unsuccessful versus successful attempts, A-K (51 +/- 11 ms vs 28 +/- 8 ms, P < 0.0001 for left pathways [LPs]; and 44 +/- 8 ms vs 31 +/- 8 ms, P < 0.02 for right pathways [RPs]) and delta-K intervals (2 +/- 9 ms vs -18 +/- 10 ms, P < 0.0001 for LPs; and 13 +/- 7 ms vs 5 +/- 8 ms, P < 0.02 ms for RPs) were significantly longer.

CONCLUSIONS

Short A-K interval (< 40 ms), and a negative delta-K interval recorded from the catheter positioned in the atrium are strong predictors of successful ablation of LPs and RPs. Therefore, the identification of the K potential appears to be of paramount importance for positioning of the ablation catheter, followed by analysis of A-K and delta-K unipolar electrogram intervals. However, it appears that the mere recording of K potential is not, per se, predictive of successful outcome, but rather the A-K and delta-K interval.

[Transcatheter radiofrequency ablation in supraventricular tachycardia in children: immediate results and mid-term follow-up]

OBJECTIVES

The purpose of this study was to evaluate the efficacy and safety of radiofrequency ablation of supraventricular tachycardias due to a reentry circuit in a group of closely followed-up pediatric patients.

PATIENTS

Forty-six pediatric patients (mean age 12.6 years, range 3-18) underwent a total of 48 radiofrequency ablation procedures for reciprocating supraventricular tachycardia. Thirty-nine had an orthodromic reentry tachycardia, 6 an atrioventricular node reentry tachycardia and 1 a permanent junctional reciprocating tachycardia.

METHODS

To ablate the overt accessory pathways, the Kent potential (K) was identified and then the shortest A-K, and delta wave-K intervals were measured. The shortest V-A interval was identified for those concealed. For the left-sided accessory pathways, we used the retrograde transaortic approach in 10 procedures and the transseptal approach in 18. Atrioventricular node reentry tachycardia was ablated at the site where the slow-pathway electrogram was recorded. Follow-up clinical data, electrocardiogram, 24-hours Holter monitoring and transesophageal atrial stimulation were obtained and evaluated.

RESULTS

Early: We performed a total of 48 procedures. Among 41 procedures performed in the 39 patients with accessory pathway, 38 were successful (92,6%). Mean fluoroscopy time was 31 +/- 18 min. For left sided accessory pathways, mean fluoroscopy time of procedures with retrograde approach was 45 +/- 10 min and with transseptal 23 +/- 12 min (p < 0.01). Ablation of slow-pathway in patients with intranodal reentry tachycardia was successful in 3/6 cases (50%). The patient with permanent junctional reciprocating tachycardia was successfully ablated. Late: All patients are alive and none was lost during the follow-up after a mean time of 12.9 months (range 5-33). Success at last follow-up was 100% in patients with an accessory pathway and 33% in patients with atrioventricular node reentry. In patient with permanent junctional reciprocating tachycardia, the arrhythmia appeared again one month after the procedure, thus a second successful attempt was performed.

COMPLICATIONS

Major complications (6,5%) including a right femoral vein thrombosis (one patient), an hematoma without pulse loss (one patient) and a non-sustained monomorphic ventricular tachycardia (one patient).

CONCLUSIONS

Our data show high efficacy of radiofrequency ablation in pediatric patients with accessory pathways. The risks are low at follow-up evaluation, but might be helpful a longer-term follow-up in order to evaluate the risk of a long fluoroscopy time and the arrhythmogenic effect of the scar.