Pacemakers are used in small children with increasing frequency for the treatment of life-threatening bradyarrhythmias. The epicardial approach is generally preferred in these patients, to avoid the risks of vessel thrombosis. We examined the feasibility and safety of transvenous pacemaker implantation in children weighing <10 kg, via subclavian puncture, using a 4 Fr sheath introduced after a venogram was performed to evaluate the vein diameter. Progressive dilation with 5, 6, and 7 Fr sheaths preceded the insertion and placement of the endocardial lead. A subaponeurotic pocket was created in the abdominal or pectoral regions, depending upon the patient's size. Between 2001 and 2007, we treated 12 patients (median age = 16 months; range 1-32; median weight = 7.9 kg; range 2.3-10.0; 7 males), of whom four weighed <5 kg. Indications for permanent pacing included postsurgical complete atrioventricular block (n = 8), sinus node dysfunction (n = 2), congenital atrioventricular block (n = 1), and long QT syndrome (n = 1). Single-chamber pacemakers were implanted in 10, and dual-chamber pacemakers in two patients. The patients were evaluated at 48 hours, 10 days, and at 3 and 6 months. The mean follow-up was 31.8 +/- 23.5 months. There were no procedural complications. Lead dislodgment occurred in one patient and required replacement of the ventricular lead. One patient died from septicemia. Endocardial pacemaker implantation was feasible and safe in children weighing <10 kg. This procedure is less invasive than the standard epicardial approach.
Pacemaker-mediated tachycardia (PMT) remains a clinical problem in patients with dual-chamber pacemaker despite technological advances. The onset mechanism of this tachycardia is sensing of retrograde atrial activation after ventricular stimulation. Repeated retrograde conduction perpetuates tachycardia. Postventricular atrial refractory period prolongation has been used for prevention of PMT, but this is not the solution in all cases. We present a case with PMT where the retrograde limb is a left accessory pathway, which is treated with radiofrequency ablation successfully.
Introduction Hypertrophic Obstructive Cardiomyopathy (HOCM) is an important cause of sudden death and heart failure, specially in young adults. Approximately 5% to 8% of patients are not suitable for transcoronary ablation, if myectomy is not feasible, Endocardial Radiofrequency Ablation of Septal Hypertrophy (ERASH) has shown acceptable efficacy and safety for left ventricular outflow tract (LVOT) gradient reduction. 20 ERASH cases have been reported in the literature. Case report 39 year old woman with diagnosis of HOCM, symptoms of dyspnea (NYHA III), and aborted sudden death as first clinical manifestation; a cardiac defibrillator was implanted. A transthoracic echocardiogram (TTE) revealed normal left ventricle (LV) ejection fraction, moderate mitral regurgitation (systolic anterior valve motion), basal inter-ventricular septal wall thickness of 20 mm generating a LVOT gradient of 51 mmHg. A coronary angiography showed inadequate septal branch anatomy to perform alcohol ablation. The patient refused myectomy. Heart Team decided to perform ERASH. Using a 3D Cardiac Mapping System and 2D Echocardiography, the basal interventricular septum received 50 Watts/50˚C radiofrequency ablation without any acute complication. Three days later, a TTE showed LVOT gradient 26 mmHg. The description of the LV mechanics is described on Table 1. Pre and post ERASH ventricular mechanics was analyzed including circumferential endocardial and mesocardial strain and strain rate, as well as longitudinal strain involved in the LV segments that received ERASH (Figure 1.) . Conclusion We report the analysis of ventricular mechanics after a successful case of ERASH, an alternative technique for treating HOCM. In our analysis, pre- ERASH longitudinal strain was significantly more negative at the basal anterior and anteroseptal segments than the other LV segments. This may be a predictor of focal LV remodeling at these segments in the future. Table 1. Pre ERASH Post ERASH Ventricular Segment Strain Strain Rate Strain Strain Rate Longitudinal Strain Basal Anteroseptal -14.4% -1.2 1/s -7% -0.6 1/s Endocardial Circumferential Strain Basal Anteroseptal -13.7% -1.9 1/s -32% -2.2 1/s Basal Anterior -44.6% -4.2 1/s -18.6% -1.6 1/s Mesocardial Circumferential Strain Basal Anteroseptal -7.7% -1.0 1/s -20.2% -1.2 1/s Basal Anterior -24.9% -1.7 1/s -13.8% -0.9 1/s Left ventricular mechanics pre and post ERASH. Abstract P1708 Figure 1.
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