A genomic phage clone containing a fulllength copy of a functional human gene for ferritin heavy chain has been isolated. The gene consists of four exons spanning approximately 3 kilobases and has been localized to chromosome 11. The functionality of the gene was demonstrated by the fact that both transient transfectants and stable transformants of murine fibroblasts actively transcribe human ferritin heavychain mRNA.

This initial psychometric investigation of the FPAS suggests that the FPAS may be useful in both clinical and research settings to assess patient acceptance of implantable cardiac devices.

BACKGROUND Atrioventricular (AV) nodal reentrant tachycardia is classically described as a reentrant rhythm entirely contained within the compact AV node. Although the concepts of longitudinal dissociation of two intranodal pathways and a distal common pathway are accepted, the proximal portion of the circuit remains undefined. Current reports suggest that the two pathways may be separable by atrial tissue and not contained entirely within the compact node. METHODS AND RESULTS We used an ice mapping method to demonstrate the slow and fast pathways of the reentrant circuit and their relation to the atrial septum around the AV node. Six patients with the usual form (slow-fast) of AV nodal reentrant tachycardia were mapped during surgery. In most patients, antegrade slow pathway localization was posterior and inferior to the compact AV node along the tricuspid annulus; in two patients, it was superior along the tendon of Todaro. Retrograde fast pathway localization was anterior or superior to the compact AV node in all patients. In all patients, anatomic distinction was made between the two pathways and the compact node. CONCLUSIONS We conclude that no upper common pathway exists within the compact AV node in the usual type of nodal reentrant tachycardia and that the perinodal atrial tissue is a requisite part of the tachycardia circuit.

The study assessed the long-term outcome of patients undergoing radiofrequency ablation of the right bundle for bundle branch reentrant ventricular tachycardia. Bundle branch reentrant tachycardia was diagnosed in 16 patients (ejection fraction 31% +/- 15%) who underwent electrophysiology study in our laboratory. All patients had His-Purkinje system conduction delay with mean HV interval of 68 +/- 8 ms. After ablation, right bundle branch block developed in 15 patients. One patient developed complete heart block, which was anticipated. One patient died of heart failure 9 months after ablation. Two patients were successfully bridged to heart transplantation 0.5 and 13 months, respectively, after ablation. Two patients received implantable defibrillators for other ventricular tachycardias. One patient had syncope 11 months after ablation, but there was no evidence of ventricular tachycardia or heart block in repeat electrophysiology study. This patient died suddenly 29 months after ablation. The remaining nine patients were alive and well for a mean follow-up of 19 +/- 10 months. Radiofrequency ablation of the right bundle branch is an effective therapy for treatment of bundle branch reentrant ventricular tachycardia. Survival is excellent provided that other types of ventricular tachycardia, when present, are treated as well. This technique may be helpful in management of patients who have unacceptable frequent shocks from their implanted defibrillators and may be helpful in avoiding implantation of such a device completely in others. In some patients with terminal heart failure and incessant ventricular tachycardia, this procedure can function as a bridge to cardiac transplantation.

Adenosine has been shown to inhibit anterograde and retrograde conduction through the atrioventricular (AV) node while having little or no effect on accessory pathway conduction. Its rapid onset of action and short half-life make it particularly suitable for repetitive measurements. In this study, the utility of adenosine was tested in assessing completeness of accessory pathway ablation. Sixteen patients with an accessory pathway were studied (eight surgical ablations, eight catheter ablations with radiofrequency energy). Before ablation, no accessory pathway was sensitive to adenosine. Twelve patients with pre-excitation showed high grade AV node block with maximal pre-excitation on the administration of adenosine during atrial pacing. Four patients with a concealed accessory pathway demonstrated high grade AV block without evidence of latent anterograde accessory pathway conduction. Preablation ventriculoatrial (VA) block was not observed in any of the 16 patients in response to adenosine during ventricular pacing. Immediately after accessory pathway ablation, all patients developed AV and VA block with the administration of adenosine during atrial and ventricular pacing, respectively. These findings were confirmed during follow-up study 1 week later. Atrioventricular block during atrial and ventricular pacing with adenosine affords a reliable and immediate assessment of successful pathway ablation.

The left-sided His-Purkinje system is the preferred retrograde route of impulse propagation during both left and right ventricular extrastimulation. Reentry within the His-Purkinje system elicited by right ventricular extrastimulation involves both bundle branches, whereas this reentry tends to occur within the left-sided His-Purkinje system during left ventricular pacing.

The Endotak lead system and ICD has been used to treat patients with malignant ventricular arrhythmias. We analyzed the clinical characteristics of 1,053 patients who underwent implantation of the Endotak lead system with or without a subcutaneous patch. Group A consisted of 567 patients receiving the Endotak lead with a subcutaneous patch; group B consisted of 486 patients receiving the Endotak lead alone. The 2-year survivals from sudden death, cardiac death, and total death in groups A and B were 97.6%/98.2% (P = 0.38), 88.6%/92.7% (P = 0.09), and 84.7%/86.8% (P = 0.06), respectively. Minimum tested effective defibrillation energy at implantation was 17.2 +/- 5.2 J for group A and 15.8 +/- 5.1 J for group B (P < 0.01). The operative mortality was 1.8% in group A and 0.6% in group B (P = 0.09). The incidence of lead dislodgment, malfunction, and infection was 6.7% for group A and 3.5% for group B (P < 0.01). Sudden death survival was excellent in both groups with less lead complications in group B. The Endotak lead alone may be the preferred choice of lead configuration in those patients who have adequate defibrillation thresholds at implant.

In most reports on patients receiving implantable cardioverter defibrillators, shocks were received mainly during the first 2 to 3 years. Thus, the question had been raised as to the need for device replacement after 3 or 4 years if no shocks had been received. In order to answer this question, shock experience in 184 patients receiving the implantable cardioverter defibrillator was analyzed. Patients were followed for a mean of 24 +/- 18.7 months. A patient's shock was judged to be appropriate if there was electrocardiographic documentation of sustained ventricular tachyarrhythmia at the time of shock or if it was preceded by sudden onset of presyncopal or syncopal symptoms. The majority of patients had coronary artery disease. In approximately two-thirds of patients, left ventricular ejection fraction was below 40%. One hundred fourteen patients had inducible sustained monomorphic ventricular tachycardia. On follow-up, there were 29 deaths, five of which were sudden. Sixty-eight patients received an appropriate shock during follow-up (37%). Over 90% of these 68 received their first shock within the 2 years after implant. The actuarial risk of receiving an appropriate shock by the fifth year after implant was 69%. Conversely, 31% of patients who survived 5 years had not received an appropriate shock. Hazard analysis indicates that there is a high incidence of first appropriate shock during the year following implant. Subsequently, the incidence dropped to a relatively steady rate with a rise in this rate during the fifth year. This analysis suggested a bimodal distribution of appropriate shocks.(ABSTRACT TRUNCATED AT 250 WORDS)