Heart rate variability patterns before ventricular tachycardia onset in patients with an implantable cardioverter defibrillator. Participating Investigators of ICD-HRV Italian Study Group.

Time- and frequency-domain analysis of heart rate variability (HRV) has been proven effective in describing alteration of autonomic control mechanisms and in identifying patients with increased cardiac and arrhythmic mortality. Patients with implantable cardioverter defibrillators offer the opportunity to evaluate HRV patterns before ventricular tachycardia (VT) and under control conditions. We therefore analyzed time- and frequency-domain parameters of short-term HRV and power-law behavior of RR interval time series at rest, at 15 to 30 minutes, and immediately before VT. In comparison to control conditions, lower values of mean cycle length duration and total power were observed before VT. Spectral analysis indicated that the low- to high-frequency ratio was significantly higher (5.5 +/- 0.6 vs 2.8 +/- 0.3) immediately before VT than during rest. Both findings were consistent with the shift of sympathovagal balance toward sympathetic predominance and reduced vagal tone. Before VT, a more negative value of the scaling exponent beta of the power-frequency relation (-1.57 +/- 0.04 vs -1.33 +/- 0.04) also confirmed the presence of an altered HRV pattern in comparison to controls. Thus, both abnormal autonomic modulation and dynamic patterns of HRV seem to characterize the minutes before arrhythmia onset in these patients.

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.

High impedance low energy pacing leads: long-term results with a very small surface area steroid-eluting lead compared to three conventional electrodes.

We evaluated the handling performance at implant, and the long-term atrial and ventricular electrical performance of a new generation using a very small surface area (1.2 mm2) steroid-eluting electrode (Medtronic CapSure Z). We compared the performance of CapSure Z to that of traditional passive fixation leads, with and without steroid elution. The study was conducted during 2 years of follow-up. We studied 188 patients (105 males and 83 females; mean age 71 +/- 7 years). All of the patients were implanted with a dual chamber pacemaker and the same type of lead in both chambers. Forty-one patients received CapSure Z leads, 25 patients received Target Tip leads (8-mm2 surface area; no steroid elution), 63 patients received CapSure leads (8-mm2 surface area; steroid elution), and 59 patients received CapSure SP leads (5.8-mm2 surface area; steroid elution). The four groups were homogeneous in regards to sex, age, cardiac disease, and reason for implant. At follow-up, the CapSure Z lead showed sensing values comparable to the other leads, with lower pacing thresholds and higher pacing impedance in both chambers. We evaluated the mean current drained from the pacemaker by the different types of leads when using safe, low energy output settings. We found that by using CapSure Z leads, the mean current was significantly lower than that of the other types of leads (0.42 microA for CapSure Z ventricular lead vs 0.85 for CapSure SP, 1.42 for CapSure, and 1.54 for Target Tip). Thus, the use of the CapSure Z lead, combined with low energy output programming, will increase pacemaker longevity compared to the use of traditional leads and standard output programming.

[Electromechanical dissociation in myocardial infarction. Anatomical-clincal study of 82 cases]. / Dissociazione elettromeccanica nell'infarto miocardico. Studio anatomo-clinico di 82 casi.

UNLABELLED: In our experience electromechanical dissociation (EMD) is the most common mechanism of fatal cardiac arrest in patients with acute myocardial infarction (AMI). METHODS: We reviewed retrospectively 82 autopsy cases of AMI in whom the medical record documented EMD as terminal cardiac arrest in order to outline the clinical and pathologic features of different subgroups: 26 cases with external cardiac rupture (CR) were compared with 56 cases without CR. In turn, inside the latter series, 16 cases of sudden EMD were compared with 40 cases of EMD occurring in the terminal phase of cardiac shock. RESULTS: In comparison with those without CR, patients with CR showed at multiple regression analysis less evidence of left ventricular failure (p < 0.05); less extended infarct areas (p < 0.01); more frequent sudden EMD (p < 0.05). Most patients with CR had massive pericardial effusion; cardiac rhythm at the onset of EMD was seldom slow in those cases. In the group without CR no discriminant characteristics were found in cases of sudden EMD vs cases preceded by cardiac shock. CONCLUSIONS: In case of CR EMD occurs in less extensively damaged hearts and is generally sudden; in AMI without CR EMD may affect patients with severe depression of pump performance, but not necessarily in shock. EMD after an AMI may result from several factors: cardiac tamponade is prevalent in the presence of CR; in cases without CR our data don't permit to conjecture a distinct pathogenesis for sudden EMD in comparison with cases preceded by shock.

Accuracy of telemetry signals in the post-implantation monitoring of electrograms sensed by pacemakers.

Monitoring of electrograms (EGMs) sensed by pacemakers (PMs) during their lifetime is the utmost importance, since changes of these signals, due to modifications of the electrode-myocardial interface may occur compromising the proper functioning of the PM. Since after implantation these intracardiac signals are accessible only by means of a telemetry system, it is necessary to ascertain how faithfully the telemetric signals reproduce the direct ones. To this aim we devised an accurate method, based on linear system theory, which allows the estimation of the transfer function of the PM-telemetry system and the comparison of a set of time and frequency domain parameters (wave amplitude, slew rate, frequency at the spectrum peak and bandwidth) computed on both direct and telemetric signals. To overcome the problem that these two signals cannot be recorded simultaneously, an appropriate model of the input and output signals of the PM-telemetry system and of their interrelationship was identified. This model relies on a set of reasonable assumptions about the nature of the direct signal (supposed to have a fixed morphology within a predefined analysis window) and of noise sources corrupting both the direct and telemetric signals. Owing to the involvement of deterministic and stochastic signals, the theory of quasi-stationary signals was employed to obtain the system transfer function. To test our method, direct and telemetric recordings were performed on 12 patients with atrial sensing carrying Medtronic Pacemakers (Mod Elite 7077/7086, programmer Mod 9760) with unipolar steroid eluting leads (Medtronic Capsure 4523). The results we obtained demonstrate that the specific system considered acts as a low-pass filter with a -3 dB frequency at about 90 Hz this ensures that the telemetric signal contains almost all the information of the direct one and can be used to monitor the changes of the signals sensed by the PM.

[The early echocardiographic diagnosis of a massive pulmonary embolism]. / Diagnosi ecocardiografica precoce di embolia polmonare massiva.

BACKGROUND: In several cases of clinically suspected massive pulmonary embolism (MPE), a lung perfusion scanning and/or a pulmonary angiography are not quickly available or feasible. METHODS: Fifty patients admitted to our ICU with a clinically suspected MPE underwent an echocardiographic (Echo) investigation very shortly after onset (within 2 hours in 38 cases, and within 6 hours in 12). An Echo-Doppler study was also performed in 18 patients. RESULTS: Highly significant differences (p < 0.001) emerged between patients with PE and healthy age-mates for each type of Echo measurement and in all views. The RVDD/LVDD ratio turned out to be the most frequently affected parameter, being altered in 96% of cases. An abnormal diastolic leftward shift of the interventricular septum was detected in 81% of cases. Only one of our 50 patients failed to show any evidence of RV pressure overload; however, this was a patient with a severe dilated cardiomyopathy. In 22 cases in whom hemodynamic monitoring was performed, no significant correlation emerged between RVDD and LVDD, on one hand, mean PAP and cardiac index on the other. All 18 patients examined by Echo-Doppler had mild to moderate tricuspid regurgitation with a peak RV-RA gradient of 38 +/- 7 mm Hg (range 31-53 mm Hg). Seven patients (14%) were found to harbor right heart thrombi when first examined. Overall mortality in this uncommonly high risk population was as high as 28%. CONCLUSIONS: In a clinical setting suggesting a MPE, an Echo study conducted very shortly after onset may corroborate a tentative diagnosis of PE, thereby permitting timely fibrinolytic therapy pending a lung scan and/or angiography, or in situations where such imaging facilities are not available or readily usable.

[Heart arrest in acute pulmonary embolism. An anatomo-clinical study]. / L'arresto cardiaco nell'embolia polmonare acuta. Studio anatomo-clinico.

The Authors describe the modalities and mechanisms of cardiac arrest (CA) in the course of acute pulmonary embolism (PE). Clinical data refer to 39 CA episodes occurred in 28 patients with massive or submassive PE; autopsy data are from 26 of 28 patients of the same series. One-third of 39 CAs proved at least momentarily reversible; two-thirds were irreversible. Data analysis showed that most CA episodes, reversible or otherwise, seen in the course of PE were due to electromechanical dissociation (EMD). In fact, EMD was responsible for 12 of 13 reversible CAs and 22 of 26 irreversible arrests. EMD usually follows shock, but may occur unheralded. When EMD-induced CA is at least temporarily reversible, the heart rate is often normal or high and QRS complexes are narrow. In most cases the sudden rise of right ventricular afterload came on top of a pre-existing myocardial damage, for the most part of ischemic, sometimes necrotic, origin. In this series, therefore, it seems quite difficult to tell "primary" from "secondary" forms of EMD. External cardiac massage continued for as long as 40 minutes was associated in some cases with a bolus fibrinolytic infusion within minutes from occurrence of CA. Five of 7 patients so treated made a temporary recovery and two survived; at autopsy, none of the 5 patients who died showed any evidence of bleeding attributable to local injury.

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.

[Pulmonary embolism in the coronary care unit]. / L'embolia polmonare in unità di cure coronariche.

Massive pulmonary embolism (MPE), as seen in cardiac care units (CCU), is almost invariably characterized by severe obstruction of the pulmonary vasculature and/or a background of poor cardiorespiratory conditions, all contributing their share to a grave overall situation, often compounded by cardiogenic shock and not exceptionally eventuating in cardiocirculatory arrest (CCA). In such circumstances, echocardiography offers both direct and indirect diagnostic elements that may help, among other things, differentiate pulmonary embolism from acute myocardial infarction--the latter not always easily identified, also in view of its possible occurrence in association with MPE. Conversely, some problems are still open concerning the meaning and treatment of right-sided intracavitary thrombus formations revealed by echocardiography. Among less familiar hemodynamic aspects we must consider right-sided pulsus alternans and the so-called ventricularization of pulmonary pressure curves--a phenomenon to be viewed with caution because of possible modifications imputable to the recording system. Bedside pulmonary angiography, now generally feasible with standard CCU equipment, may readily diagnose or rule out MPE in situations where an angiography room is not available or momentarily not accessible. Numerous personal anatomoclinical observations bear witness to the role of electromechanical dissociation (EMD) as a cause of CCA in patients with MPE. Such dissociation may prove at least temporarily reversible, especially in cases not featuring bradycardia and showing narrow QRS complexes; the concurrent administration of fibrinolytic agents along with cardiopulmonary resuscitation may prove successful while it does not seem to invite important hemorrhagic complications.

[Amiodarone prophylaxis of ventricular tachycardia in ischemic cardiopathy]. / Profilassi con amiodarone della tachicardia ventricolare nella cardiopatia ischemica.

Sustained ventricular tachycardia (VT) in coronary heart disease (CHD) represents a major risk factor for sudden death. The Authors evaluated the prophylactic efficacy of the chronic administration of amiodarone (A) on this arrhythmia and simultaneously the trend of ventricular extrasystole during the antiarrhythmic treatment. Twenty-three patients were examined, 17 with post-infarction cardiopathy and 6 with mixed angina. They showed either 1 or more episodes (2 patients) of sustained VT involving hemodynamic difficulties. The ejection fraction (EF) ranged between 20 and 45% average (35.2 +/- 9). All patients underwent a basal 24 hour ECG 3 days after the VT cardioversion, and every 6 months. All subjects took A orally for a period ranging from 7 to 67 months (average 23.04 +/- 14) at the dose of 800 mg/day 7 for days, and then 200 or 400 mg/day according to the presence or absence of ventricular extrasystoles (VE) greater than or equal to 30/hr and/or Lown's class (L) greater than or equal to 3. No patients died suddenly during the follow-up; 6 of them died for causes other than arrhythmia. Four of them showed only 1 sustained VT relapse after a period of 6 to 11 months. Two of these 4 patients showed a persistent increase of the number of VE and L-class while, in the remaining 2 patients, the number of VE remained substantially unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)

[Informatics in cardiology: proposal for standardized terminology in clinical records and in permanent cardiac electrostimulation]. / Informatica en cardiología: propuesta para una terminología estandarizada para el expediente clínico y la electroestimulación cardíaca permanente.

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.

[Use of the subclavian vein for permanent cardiac stimulation]. / Empleo de la vena subclavia para la estimulación cardíaca permanente.

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.

[Auriculo-ventricular block upon swallowing]. / Bloc auriculo-ventriculaire à la déglutition.

A case of recurrent syncopal attacks in a 70-year-old woman with oesophageal hiatus hernia is reported. Dynamic ECG recording showed paroxysmal II and III degree A-V block during solid food swallowing. Electrophysiologic examination was normal in the basal condition and showed a II degree A-V nodal block with 2: 1 conduction ratio during solid food swallowing. This phenomenon was not reproducible after atropine administration. A permanent cardiac pacemaker (VVIP) rendered the patient completely symptomfree. The likely pathogenetic mechanism of "swallowing A-V block" is described.

[Comparative evaluation of mexiletine and propafenone by dynamic electrocardiography]. / Valutazione comparativa tra mexiletina e propafenone mediante elettrocardiogramma dinamico.

We have compared the efficacy of Propafenon and Mexiletine in 12 subjects (7 males and 5 females, age range of 22-61 year) affected by chronic ventricular extrasystolic beats. Propafenon and Mexiletine were orally administered in doses of 900 mg/day and 600 mg/day respectively in a single blind, cross-over fashion. Our results show that: Propafenon is better tolerated; Propafenon has caused a statistically significant reduction of the total number of ventricular ectopic beats/24 hours; the efficacy of Propafenon has been greater than that of Mexiletine (66% and 25% respectively); with both drugs, in 2 cases, there was an increase of the total number of ventricular ectopic beats/24 hours; Propafenon has induced clear-cut electrocardiogram changes (statistically significant lengthening of P-Q and Q-T intervals).

[Threatening arrhythmia by uncommon digitalic toxicosis (author's transl)]. / Aritmia minacciosa da non comune intossicazione alimentare.

The authors describe the case of a 38 year old woman who ate some buds of "Helleborus viridis" collected in the mountains mistaken for wild asparagus. The clinical patterns were like in the digitalic toxicosis: the woman presented both ventricular and supraventricular threatening arrhythmias, gastro-enteric troubles, systemic hypotension. The patient improved with the glucose, potassium chloride and magnesium sulphate infusion and intravenous xylocaine. The authors conclude that in case of patient with threatening arrhythmias of unknown genesis it is useful to pay attention to the wild vegetables ingestion.