[Evolution of pacing modes in patients with implanted pacemakers. Personal considerations on a case load of 171 patients]. / Evoluzione della modalità di stimolazione nei pazienti portatori di pace-maker. Considerazioni personali su una casistica di 171 casi.

In this study retrospectively analyse pacemaker-implantation activity carried out during the last 5 years at the Laboratory of Electrophysiology, affiliated with the Cattedra di Cardiologia of the University of Naples--II Ateneo. Evolution in pacing modes is considered with regard to the patient age, the underlying pathologies and the technical progress in the field. The study has been performed in our laboratory, which is fit up for electrophysiologic studies and implantation of either temporary or permanent pacemakers. Patients included in this study have been implanted in our laboratory either for urgency or for election. They have been retrospectively divided into two groups (age < 65 yrs, 129 patients, and age < 65 yrs, 42 patients); in addition the patients have been classified according to the pathology leading to the implantation: atrio-ventricular block (second degree or third degree), low frequency fibrillation, sick sinus syndrome and carotid sinus syndrome. 171 patients have been examined, of whom 129 > 65 yrs. and 42 < 65 yrs. As for the pacing indication, 54 were atrio-ventricular block (56.1%), 50 were sick sinus syndrome (31.6%), 20 low frequency fibrillation (11.7%), and 1 was carotid sinus syndrome (0.6%). The ratio between single- and dual-chamber pacemakers has been progressively changing: in 1987 we implanted 33 single-chamber and no dual-chamber pacemaker, compared to 7 single- and 23 dual-chamber pacemaker implanted in the last year. This trend is in good agreement with literature data.

[Slow and fast AV nodal pathways in tachycardia complicating Wolff-Parkinson-White syndrome: report of a case]. / Partecipazione delle vie lenta e rapida del nodo AV nella tachicardia della preeccitazione ventricolare: descrizione di un caso.

Electrophysiologic studies in a patient with intermittent ventricular pre-excitation revealed several types of paroxysmal narrow-QRS tachycardia (PSVT). One type of PSVT was characterized by normal retrograde atrial sequences with P waves occurring simultaneously with QRS. This type of PSVT reflected AV nodal reentry with anterograde slow pathway and retrograde fast pathway conduction. A second PSVT reflected alternation of anterograde fast and slow AV nodal pathway conduction and retrograde anomalous pathway conduction. A third PSVT reflected anterograde slow AV nodal pathway and retrograde anomalous pathway conduction. Moreover, discontinuous AV nodal conduction curves (A1A2/H1H2), characteristic of dual AV nodal pathway conduction, were obtained with programmed atrial extra stimulation. These observations suggest that dual AV nodal pathway conduction can coexist with abnormal bypass tract and can be the cause of PSVT in patients with Wolff-Parkinson-White syndrome.

[EGG and arrhythmia in subjects with implanted dual-chamber VDD and DDD pacemakers]. / ECG e aritmie in soggetti portatori di stimolatori bicamerali VDD e DDD.

The ECGs of four patients with implanted dual chamber VDD and DDD PMKs are shown to demonstrate the difficulty of their interpretation and show some arrhythmias related to dual chamber pacing. In the first patient the DDD PMK caused a high ventricular frequency synchronizing on the atrial fibrillation "f" waves which occurred suddenly some time after PMK implantation; this problem was solved by programming the PMK in VVI. The second and third case, with implanted DDD and VDD PMK respectively, exemplify atrial sensing dysfunction due to atrial catheter displacement. In the fourth patient, with implanted VDD PMK, VDD stimulation periods and VVI ones alternated due to non-adjusted programming. Therefore, the paper re-emphasizes the need for accurate and periodic controls of patients with implanted PMK to correct dysfunction or undesirable patterns of stimulation.