Anna Lam

Failure rate and conductor externalization in the Biotronik Linox/Sorin Vigila implantable cardioverter-defibrillator lead

BACKGROUND We observed a case of conductor externalization in a Biotronik Linox lead. OBJECTIVE The purpose of this study was to investigate lead performance of the Linox lead and the identical Sorin Vigila lead and prevalence of conductor externalization. METHODS We compared lead performance of all Linox and Vigila leads implanted at our center (BL group; n = 93) with that of all Boston Scientific Endotak Reliance leads (ER group; n = 190) and Medtronic Sprint Quattro leads (SQ group; n = 202) implanted during the same period. We screened all patients in the BL group for conductor externalization. RESULTS We identified 8 cases of lead failures in the BL group (index case of conductor externalization, 6 cases of nonphysiological high-rate sensing, and 1 case of high-voltage conductor fracture). Prospective fluoroscopic screening of 98% of all active BL group cases revealed 1 additional case of conductor externalization. The median follow-up was 41, 27, and 29 months for the BL group, ER group, and SQ group, respectively; lead survival was 94.9%, 99.2%, and 100% at 3 years and 88%, 97.5%, and 100% at 5 years (P = .038 for BL group vs ER group and P = .007 for BL group vs SQ group using the log-rank test). Younger age at implant was an independent predictor of lead failure in the BL group (adjusted hazard ratio 0.85; 95% confidence interval 0.77-0.94; P = .001). CONCLUSION At our center, survival of the Linox lead is 88% at 5 years and significantly worse than that of other leads. Conductor externalization is present in a minority of failed Linox leads. Younger age at implant is an independent predictor of Linox lead failure.

Phenotypic Spectrum of HCN4 Mutations: A Clinical Case

The hyperpolarization-activated cyclic nucleotide-gated (HCN) cation (Na+/K+) currents (If/Ih) are generated by 4 members of the channel family (HCN1–4).1 These currents contribute to the pacemaker function2 in heart and brain.3 The HCN4 current is known to play a crucial role in the automaticity of the sinus node through the generation of a slow diastolic depolarization during the phase 4 of the cardiac action potential.4 Thus, it is a crucial channel for appropriate pacemaker activity and conduction system function because it facilitates rapid repolarization. Interestingly, HCN4 has been shown to be expressed in essentially the entire heart tissue.5 Mutations in HCN4 have been associated mainly with sick sinus syndrome phenotype6; however, in recent years, a broad spectrum of phenotypes has been reported, including sinus bradycardia,7 inappropriate sinus tachycardia,8 early-onset atrial fibrillation,9,10 atrio-ventricular block,11,12 idiopathic ventricular tachycardia,13 left ventricular noncompaction (LVNC),14–17 dilation of the aorta, and mood and anxiety disorders.19 In the present study, we report a case with sick sinus syndrome, LVNC, mood and anxiety disorders, and ventricular fibrillation (VF) hosting 2 novel HCN4 -pore mutations. The index patient was a 36-year-old man, who presented initially with mood and anxiety disorders characterized by important depressive episodes. Previous clinical records revealed a slightly impaired left ventricular function, paroxysmal atrial fibrillation, frequent premature ventricular complexes, and nonsustained tachycardia originating from the right ventricle. Therapy with β-blocker was initiated but discontinued shortly because of profound sinus bradycardia, which did not resume after washout. A cardiac magnetic resonance imaging excluded a right ventricular cardiomyopathy. The left ventricle showed an uncommon hypertrabeculation; however, the criteria for an LVNC were not fulfilled at that time. Eight years later, the patient was hospitalized because of heart failure and …

Unexplained Cardiac Arrest in an Apparently Healthy Young Woman: What Is the Underlying Substrate of the Arrhythmia?

An 18-year-old woman with a history of anorexia nervosa and multiple episodes of dizziness and syncope of unknown cause was transferred to the emergency department by ambulance 1 hour after starting to feel palpitations, dizziness, tightness in the chest, and presyncope at school. At the time of presentation, she was hemodynamically stable, but the symptoms persisted. The ECG recorded at admission is shown in Figure 1A. A supraventricular tachycardia with aberrancy was suspected. Conversion attempts first with vagal maneuvers (carotid sinus massage and Valsalva maneuver) followed by adenosine (6 mg IV) were unsuccessful, but the ventricular rate and the QRS duration normalized gradually within 12 hours. The full cardiovascular and laboratory workup showed unremarkable findings, and the patient was discharged with prescription of metoprolol 25 mg/d. Figure 1. ECG obtained at the time of initial admission and readmission to the emergency department. A , The ECG recorded at initial admission shows regular wide-QRS complex tachycardia with right bundle-branch block morphology and a ventricular rate of 120 bpm, no identifiable P waves, and no atrioventricular dissociation. B , The ECG recorded at readmission shows agonal heart rhythm with …

The search for atrial fibrillation and its impact on public health

Atrial fibrillation may be clearly symptomatic and is easily amenable to state-of-the-art treatment, most importantly oral anticoagulation therapy for the prevention of thromboembolism. However, atrial fibrillation may also go unnoticed for long periods in many patients. This silent or subclinical atrial fibrillation is nevertheless associated with thromboembolic risk just like clinically evident atrial fibrillation. Early detection of atrial fibrillation in patients at increased thromboembolic risk and consequent oral anticoagulation therapy may have a significant impact on public health. This review focuses on screening recommendations for atrial fibrillation and on the impact of silent atrial fibrillation in various clinical scenarios.

Ein Herz im Rasermodus

Eine 50-jahrige Patientin stellt sich wegen seit letzter Nacht persistierenden Palpitationen, retrosternalem Druckgefuhl und Schweissausbruch auf der Notfallstation vor.