[An intrapatient comparison of adaptation to aerobic and anaerobic exertion during 3 types of physiological cardiac stimulation in chronotropic failure of the sinus node: DDD, VVIR and DDDR]. / Confronto intrapaziente dell'adattamento allo sforzo aerobico ed anaerobico durante tre tipi di stimolazione cardiaca fisiologica nell'insufficienza cronotropa del nodo del seno: DDD,VVIR e DDDR.

In sick sinus syndrome with chronotropic incompetence, dual-demand rate responsive pacing (DDDR) may be better than ventricular-inhibited rate responsive pacing (VVIR) and dual-demand pacing without rate responsive function (DDD). In order to compare exercise performance during different activity-driven pacing modes, 15 patients (9 males, 6 females; mean age 59 +/- 13 years), implanted with Synchrony 2020T pacemaker (Siemens-Pacesetter Inc, USA, activity sensor) for sick sinus syndrome, randomly performed 3 treadmill tests (modified Bruce protocol) during DDD, VVIR and DDDR pacing, with pacing heart rate, oxygen consumption (Q-Plex 5000, Quinton), work time, anaerobic threshold and human atrial natriuretic peptide level monitoring. Four patients were excluded from the data results (3 for normalization of chronotropic incompetence, 1 for angina pectoris during rate responsive pacing). Heart rate at the end of exercise was significantly higher during VVIR pacing mode (131 +/- 21 b/min) and DDDR (136 +/- 14 b/min) than during DDD pacing mode (105 +/- 21 b/min), p < 0.05. During DDDR we obtained a significantly higher work tolerance (652 +/- 161 s) and a higher oxygen uptake (22.7 +/- 7.1 ml/kg/min) than during DDD (565 +/- 106 s; 20.1 +/- 6.5 ml/kg/min) and VVIR (599 +/- 155 s; 18.8 +/- 6.5 ml/kg/min), p < 0.05. Also the work time and the oxygen uptake at anaerobic threshold were better during DDDR stimulation (350 +/- 119 s; 14.2 +/- 4.9 ml/kg/min) than during DDD (280 +/- 101 s; 12.2 +/- 4.6 ml/kg/min) and VVIR pacing mode (306 +/- 122 s; 11.6 +/- 4.60 ml/kg/min), p < 0.05. On the contrary, human atrial natriuretic factor values at the maximum exercise were lower during DDD (139 +/- 100 pg/ml) than VVIR (256 +/- 182 pg/ml) and DDDR (209 +/- 195 pg/ml) pacing mode, p < 0.05. In conclusion, DDDR pacing proved to be better than VVIR and DDD in patients with sick sinus disease and chronotropic incompetence.

[Isolated infarction of the right ventricle caused by occlusion of the non-dominant right coronary artery. Role of sequential atrioventricular stimulation]. / Infarto isolato del ventricolo destro da occlusione di un'arteria coronaria destra non dominante. Ruolo della stimolazione atrioventricolare sequenziale.

AIM: Description of a case report. PATIENT: The case of a 66-year old woman with cardiogenic shock due to isolated acute right ventricular infarction caused by occlusion of a diminutive right coronary artery is described. RESULTS: Her ECG showed the presence of junctional rhythm and ST elevation in V1-V2 and right precordial leads. Despite infusion of plasma expanders, atropine and inotropic agents, clinical conditions did not improve, but success was only achieved by means of atrioventricular (AV) sequential pacing which allowed good hemodynamic stabilization of the patient. CONCLUSIONS: It is noteworthy that occlusion even of a diminutive right coronary artery can induce cardiogenic shock, and that restoration of the physiological AV synchrony--although somewhat impaired by prolonged atrial stunning--has a markedly positive effect on the hemodynamic balance.

Effect of steroid eluting versus conventional electrodes on propafenone induced rise in chronic ventricular pacing threshold.

The aim of this study was to evaluate chronic ventricular pacing threshold increase after oral propafenone therapy. Eighty-three patients affected by advanced atrioventricular block and sick sinus syndrome were studied at least 3 months after pacemaker implantation, before and after oral propafenone therapy (450-900 mg/day based on body weight). The patients were subdivided into three groups according to the type of unipolar electrode that was implanted: group I (41 patients) Medtronic CapSure 4003, group II (30 patients) Medtronic Target Tip 4011, and group III (12 patients) Osypka Vy screw-in lead. In all cases a Medtronic unipolar pacemaker was implanted: 30 Minix, 23 Activitrax, 14 Elite, 12 Legend, and 4 Pasys. Propafenone blood level was measured in 75 patients 3-5 hours after propafenone administration. The pacing autothreshold was measured at 0.8 V, 1.6 V, and 2.5 V by reducing pulse width. At the three different outputs before and after propafenone, threshold increments were significantly lower in group I in comparison with group II and group III (propafenone ranging from < 0.001 to < 0.05). No significant difference was found in pacing impedance or in propafenone plasma concentration in the three groups. Strength-duration curves were drawn for each group at baseline and after propafenone administration. Before propafenone, in group I, the knee was markedly shifted to the left and downward as compared to the classic curve, so that the steep part was predominant; in group II and group III this shift was progressively less evident.(ABSTRACT TRUNCATED AT 250 WORDS)

Hypertrophic peripheral neuropathy (Dejerine-Sottas disease) associated with heart block. Case report presentation and review of the literature.

We present a case of a male suffering from hypertrophic peripheral neuropathy (Dejerine-Sottas disease) and severe involvement of the cardiac conductive tissue causing syncopal attacks. It is the first time that an association of this neuromuscular disease with cardiac involvement is described.

Physician perception of exercise electrocardiography as a prognostic test after acute myocardial infarction.

To determine how physicians interpret exercise electrocardiography with respect to prognosis after acute myocardial infarction (AMI), 29 cardiologists (all board certified) were presented a case history of a 50-year-old man with an uncomplicated AMI and asked to estimate the patient's risk of dying over the next year, the sensitivity and specificity of exercise electrocardiography with respect to 1-year mortality, and the patient's risk of dying given a positive and a negative test result. Each set of physician estimates did not differ from those derived from a review of the medical literature (difference not significant for each). Risk after the test was also calculated using the Bayes' theorem. Calculated versus estimated risks were compared after a negative (7 +/- 9 vs 11 +/- 11%) and a positive (27 +/- 22 vs 17 +/- 15%, differences not significant) test result. Estimated risks were more accurate for a negative result than for a positive one (89 +/- 10 vs 83 +/- 12%, p less than 0.001). Given a positive test result, 57% of the physicians recommended coronary angiography. However, their estimates of risk (30 +/- 23%) were not significantly different from the estimates of those physicians (14%) who recommended additional noninvasive testing (19 +/- 4%) or those (29%) who recommended medical therapy (28 +/- 26%) (difference not significant). Thus, cardiologists accurately estimated prognosis following AMI, but they were less accurate in assessing high risk than low risk, and their management decisions correlated poorly with their risk assessments.