Time trends in the intracardiac potential recorded by pacemaker telemetry: comparison between steroid-eluting small area electrodes

We assessed the time course of electrograms sensed both in the atrium and ventricle by two different steroid-eluting electrodes: Medtronic Capsure SP (with an area of 5.5 mm2) and Z (with an area of 1.2 mm2). We considered 68 unipolar electrodes: 31 atrial (19 Capsure SP 4523 and 12 Capsure Z 4533) and 37 ventricular (24 Capsure SP 4023 and 13 Capsure Z 4033) implanted in 47 consecutive patients (30 men and 17 women, with an age of 72 +/- 9.4 years). The pacemaker model was Medtronic Elite 7077-7086 (DDD-DDDR) in 25 patients and Medtronic Legend 8419-8424 (VVIR-AAIR) in 22 patients. The endocavitary signal (all patients had spontaneous rhythm) was telemetrically obtained by a Medtronic 9790 device and acquired on a personal computer at implantation and 7, 30, and 180 days thereafter. The signal was studied both in the time domain and in the frequency domain by spectral analysis. The following parameters were calculated: amplitude (A): peak-to-peak value of the complex; slew rate (SR) peak negative first derivative; F0: frequency at which the power spectrum reaches its maximum value; and bandwidth (Bw): expressed as the distance between the -3 dB points and statistically analyzed by a two-way analysis of variance with factors "time" (four measurements) and "electrode" (Capsure SP and Z) and repeated measurements on the former. Ventricular sensing: no time or electrode effect (P > 0.1 in all comparisons) was found for F0, Bw, or SR, while a time effect (P < 0.04) not dependent on the type of electrode was found for the amplitude of the signal. In particular, a significant increase was found between the measurement at 6 months and that at implantation (P < 0.004). Atrial sensing: A, F0, and bandwidth were not affected by time or electrode (P > 0.09), while SR behaved differently over time (P < 0.05) in the two electrodes (the Capsure Z showed an increase at sixth month [P < 0.04] compared to implantation). In conclusion, the Medtronic Capsure SP and Z electrodes proved to be valid and substantially equivalent as far as concerns the measurement of the intracardiac potential despite the difference between their surface areas. Further studies should be devised to assess whether transitory decreases of atrial Bw in the first month of follow-up observed in a few patients for both electrodes could be responsible for clinical episodes of sensing deficit.

[Silent myocardial infarction caused by acute carbon monoxide poisoning]

This report describes a 63 year-old man who suffered an acute myocardial infarction after carbon monoxide exposure. When evaluated in the Emergency Room the patient was completely conscious and did not experience any chest pain. The electrocardiogram showed non-specific T wave abnormalities in inferolateral leads. The only sign consistent with a possible myocardial involvement was a slight increase in serum CPK. The electrocardiogram taken 12 hours later revealed a Q-wave inferior myocardial infarction, and CPK levels showed a typical elevation in the following 24 hours. The coronary angiography, performed about two weeks after admission, documented multiple obstructions in the main coronary branches. In the presence of a reduced coronary reserve, the onset of a prolonged myocardial ischemia might have been secondary to a decreased oxygen transport capacity of the blood, which lead to a decreased amount of oxygen available to the tissues. According to their experience, the authors emphasize the importance of a careful electrocardiographic and enzymatic monitoring of all patients in the first hours after CO exposure, because the typical chest pain may be absent.

Antiaggregating therapy in acute myocardial infarction

The clinical benefit of aspirin in the acute phase of myocardial infarction is dramatically suggested by the results of the ISIS-2 trial. However, the time course of pathophysiological events that lead to such a determining involvement of platelets still appears uncertain and further study is needed to single out exactly how early and how long antiplatelet drugs should be given, since there is a risk of bleeding complications due to the combination of the different antithrombotic therapies. Thrombolytic agents and heparin are in fact widely used for patients with acute myocardial infarction, even if the optimal schedule of treatment, including anti-aggregating therapy, is not yet firmly established. To avoid rethrombosis and to enhance the efficacy of coronary thrombolysis, thus reducing early mortality, several newer antiplatelet agents other than aspirin, such as antibodies against the platelet receptor of adhesive proteins, the glycoprotein IIb/IIIa and the RGD peptides, are currently under investigation.

[Well's syndrome with eosinophilic vasculitis, coronary aneurysms and myocardial infarction]

This report describes a 40-year-old man suffering from Well's syndrome (recurrent granulomatous dermatitis with eosinophilia) who presented an anterior myocardial infarction complicated by shock and 3rd degree A-V block. The patient died within 12 hours of admission to the hospital. At autopsy, both main coronary arteries showed proximal aneurysms occluded by thrombi. On light microscopy, the aneurysmatic coronary walls were infiltrated by numerous eosinophils, lymphocytes and plasma cells. Similar cellulitis, mainly perivascular, was found in kidneys and anterior mediastinum. Because the patient had been treated with large doses of diclofenac and piroxicam owing to painful arthralgias, the Authors discuss the possible allergic pathogenesis of the vasculitis.

[Acoustic, mechanical and electric alternans in heart tamponade. Clinical case and review of the literature]

The uncommon observation of alternation of the first heart sound in intensity, associated with mechanical and electric alternans is reported in a patient with cardiac tamponade due to large hemorrhagic pericardial effusion. Following pericardiocentesis and removal of 400 millilitres of fluid, all alternation phenomena disappeared. The combination of three alternation phenomena may be a helpful physical diagnostic sign of cardiac tamponade. The possible mechanisms of the "alternans" are discussed. It is suggested that variations in ventricular filling and emptying are the relevant pathogenetic factors.

[Informatics in cardiology: proposal for standardized terminology in clinical records and in permanent cardiac electrostimulation]

To make operative two medical computerized programs, one dedicated to the cardiological clinical record (PAC) and the other to permanent cardiac stimulation (PGP), we codified about 4000 terms concerning the general medical field and particularly the cardiological area. The importance of standardization of the medico-cardiological language is emphasized, specially in relation to the systematization of the information, necessary to work with computerized systems.

[Torsade de pointes caused by tricyclic antidepressive agents. Description of a clinical case]

Tricyclic antidepressant drugs are known to cause often electrocardiographic abnormalities and to induce sometimes cardiac rhythm disturbances. We report a case of a patient on antidepressant therapy (Desipramine Hydrochloride, 50 mg/die, and Dothiepin Hydrochloride, 150 mg/die), without any underlaying heart disease, admitted to our Coronary Care Unit for recurrent syncopal episodes. An ECG on admission showed Sinus Tachycardia with Ectopic Ventricular Beats and recurrent runs of Torsade de Pointes, a distinctive form of Ventricular Tachycardia. Lignocaine i.v. was only transiently effective. Both Isoprenaline and Atropine Sulphate i.v. were uneffective. Ventricular Fibrillation occurred and cardioversion was achieved by a single DC shock. Amiodarone i.v. and electrical overdrive only temporarily suppressed ventricular arrhythmias. Magnesium Sulphate i.v. (bolus + infusion) induced a definitive suppression of Torsades de Pointes. One day later no more arrhythmias were present.

[Use of the subclavian vein for permanent cardiac stimulation]

The experience on 101 cases of permanent cardiac stimulation is reported; in all of them, the access was via the subclavian vein. Punction of the subclavian artery, transient injury of the brachial plexus and pneumothorax, were seen in 4.3 and 3% respectively. Early electrode luxation was observed in 5% of the patients. As late complications there where two cases of destruction of the electrode protecting sheet and one electrode rupture. In spite of the potential risks directly related to the vein puncture, the subclavian puncture offers an excellent alternative for placing definitive pacing electrodes.

Myocardial infarction in a child aged ten with Duchenne muscular dystrophy

The authors describe the clinical picture, ECG, vectorcardiographic, and serum enzyme assays in one case of acute myocardial infarction occurring after a severe physical exertion in a child aged 10 with progressive muscular dystrophy of the Duchenne type. The picture differs considerably from the electrical aspects of "pseudonecrosis" that interstitial fibrosis of some portions of the left ventricle may produce in this myopathy.