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The term "electrical storm" (ES) indicates a state of cardiac electrical instability manifested by several episodes of ventricular tachyarrhythmias (VTs) within a short time. In patients with an implantable cardioverter-defibrillator (ICD), ES is best defined as three appropriate VT detections in 24h, treated by antitachycardia pacing, shock or eventually untreated but sustained in a VT monitoring zone. ES seems to have a low immediate mortality (1%) but frequently (50-80%) leads to hospitalization. Antiarrhythmic drugs have been shown to be very effective in treating ES in patients without ICD, whereas in ICD recipients, device programming is probably a key issue to prevent ES. Since sympathetic overreactivity is an important trigger, the risk of shock delivery should be minimized. Antitachycardia pacing can successfully terminate a significant percentage of fast VTs. Important parameters such as the number of VT cycles needed for VT detection can be increased from nominal values to allow spontaneous termination, and safety features that deliver a shock after a programmable time window independent of programming of antitachycardia pacing (sustained rate duration) should be prolonged or disabled. In some cases it may be advisable to turn off the ICD tachy mode to avoid multiple ineffective shocks. Substrate mapping and VT ablation may be useful for the treatment and prevention of ES.

BACKGROUND: Effective automatic mode switching (AMS) algorithms capable of detecting a range of supraventricular tachyarrhythmias is important given evidence of atrial fibrillation (AF), atrial flutter (AFL), and atrial tachycardia (AT) post-implantation of pacemakers. OBJECTIVES: The aim of the study was to assess the efficacy, defined as ability to detect a specific atrial rate and activate AMS, of five different AMS mechanisms during simulation of AF, AFL, and AT. MATERIALS AND METHODS: A total of 48 subjects (35 men, 13 women; mean age: 69 +/- 8 years) implanted with DDDR pacemakers utilizing five different AMS mechanisms (mean atrial rate, rate cut-off, complex 'fallback' algorithm, retriggerable atrial refractory period, and physiological band 'beat-to-beat') were tested using an external electronic device that simulated the occurrence of supraventricular tachyarrhythmias. AF, AFL, and AT were simulated by delivering low voltage pulse trains at 350, 250 and 160 beats/min, respectively. RESULTS: Mean efficacy for all AMS mechanisms was 81% [range: 57% to 100%] at 350 beats/min, 81% [range: 57-100%] at 250 beats/min, and 79% [range: 57-100%] at 160 beats/min. The AMS mechanisms that yielded 100% efficacy were the rate cut-off and physiological band 'beat-to-beat.' CONCLUSION: Not all AMS algorithms are equally efficacious at detecting atrial arrhythmias and subsequently activating AMS. Our results suggest that the most efficacious AMS algorithms are those that use rate cut-off and physiological band 'beat-to-beat' to detect supraventricular tachyarrhythmias.

Background. In order to correct the activation, contraction, and relaxation asynchronism, multisite biventricular stimulation has been proposed as a non-pharmacological alternative for the treatment of patients with congestive heart failure (CHF) NYHA class II-III-IV, resistant to maximal drug therapy and with a QRS duration > 120 ms. Fourier analysis appears a feasible technique for the quantitative and non-invasive evaluation of the inter- and intraventricular conduction delays. The aim of our study was to evaluate the usefulness of Fourier analysis when estimating the electromechanical resynchronization in CHF biventricular paced patients and to follow up these patients. Methods. Forty-five male patients (mean age 64 ± 5 years) with severe drug-refractory CHF, were submitted to radionuclide ventriculography 14 ± 7 days, 24 and 36 months after the implantation of a biventricular pacemaker, in order to assess left ventricular ejection fraction using Fourier analysis of the right and left ventricular phase images. Each patient was examined during spontaneous sinus rhythm, P-synchronous right ventricle and P-synchronous biventricular pacing. Results. Fourteen days after biventricular pacemaker implantation, QRS duration decreased from 170 ± 25 to 147 ± 25 ms (p < 0.01), left ventricular ejection fraction increased from 24 ± 6 to 31 ± 9% (p < 0.005), while standard deviation of the left ventricular phase decreased from 53 ± 6 to 35 ± 9% (p < 0.0005). Similar results were obtained at 24 and 36 months. Conclusions. Biventricular pacing appears to be associated with shortening of QRS duration and an improvement in NYHA class and left ventricular ejection fraction in CHF patients with inter- and intraventricular conduction delays as assessed at Fourier analysis radionuclide ventriculography. © 2004 CEPI Srl.

BACKGROUND: This study focuses the role of heart rate on cardiac output (CO) at rest and during walk test in patients with dual-chamber pacemaker and depressed or normal left ventricular (LV) function. METHODS AND RESULTS: In nine patients with ejection fraction (EF)

Previous in vitro studies have shown that isolated mitochondria can generate oxygen radicals. However, whether a similar phenomenon can also occur in intact organs is unknown. In the present studwy,e tested the hypothesis that resumption of mitochondrial respiration upon reperfusion might be a mechanism of oxygen radical formation in postischemic hearts, and that treatment with inhibitorosf mitochondrial respiration might prevent this phenomenon. Three groups of Langendorff- perfused rabbit hearts were subjected to 30 min of global ischemia at 37 “C, followed by reflow. Throughout ischemia and early reperfusion the hearts received, respectively: (a) 6 mM KC1 (controls), (b) 6 mM sodium amobarbital (Amytal“, which blocks mitochondrial respiration at Site I, at the level of NADH dehydrogenase), and (c) 6 mM potassium cyanide (to block mitochondrial respiration distallya, t the level of cytochrome c oxidase). The hearts were thperonc essed to directly evaluatoex ygen radical generationb y electron paramagnetic resonances pectroscopy, or to measure oxygen radical-induced membrane lipid peroxidation by malonyl dialdehyde (MDA) content of subcellular fractions. Severity of ischemia, as assessed by “P-nuclear magnetic resonance measurements of cardiac ATP, phosphocreatine, and pH, was similar in all groups. Oxygen-centered free radical concentration averaged 3.84 f 0.64 PM in reperfused control hearts, and it was significantly reduced by Amytal treatment (1.98 2 0.26; p < 0.06), but not by KCN (2.68 f 0.96 PM; p = not significant (NS)), consistent with oxygen radicals being formed in them itochondrial respiratory chain at Site I. Membrane lipid peroxidation of reperfused hearts was also reduced by treatment with Amytal, but not with KCN. MDA content of the mitochondrial fraction averaged 0.76 f 0.06 nM/mg protein in controls, 0.72 f 0.06 in KCN-treated hearts, and0 .64groups). Similarly, MDA content of lysosomal membrane fraction was0 .64 f 0.09 nM/mg protein in controls, 0.79 C 0.16 in KCN-treated hearts, and 0.43 2 0.06 in Amytal-treated hearts ( p 0.06 versus both groups). Since the effects of Amytal are known to be reversible, in a second series of experiments we investigated whether transient mitochondrial inhibition during the initial1 0 min of reperfusion wasa lso associated with beneficial effects on subsequent recovery of cardiac function after wash-out of the drug. At the end of the experiment, recoveroyf left ventriculaer nddiastolic and of developed pressure was significantly greater in those hearts that had been treated with Amytal during ischemia and earlyre flow, as compared to untreated hearts. In conclusion, our data demonstrate that in intact hearts electron flow through the respiratory chain may be an important source of oxygen radicals, which may form at the sites of interactions between Fe-S clusters and ubiquinone, and that resumption of mitochondrial respiration upon reoxygenation might contribute to reperfusion injury.

Heart failure patients may frequently undergo repeat hospitalizations, and for this reason recent guidelines recommend a multidisciplinary approach including remote clinical state management through systems such as electronic devices, portable or implantable, with the aim of simplifying patient management and optimizing healthcare resources. This different way of healthcare organization has brought about new levels of responsibility, including device manufacturers responsible for the technical aspects, healthcare facilities responsible for the information systems used for patient clinical data transmission and for ambulatory patient access, and in particular the clinicians who should ensure the process supervision by providing prompt medical assistance if alarm signals are received. The use of telemedicine, however, may engender technical problems of varying difficulties. In terms of responsibility, service providers are not liable for damage deriving from technical default, except in the case of willful misconduct or gross negligence. No less important are the legal issues concerning permissions, conflicts of jurisdiction among nations, problems of service inaccessibility, as well as the identification of medical liability in relation to the activity of a multidisciplinary team, besides issues relating to informed consent and privacy protection. In conclusion, risk management with telemedicine may provide more accurate information and better traceability of operators' activity.

Skin ulcers are a dangerous and uncommon complication of vasculitis. We describe the case of a teenager suffering from Systemic Lupus Erythematosus with digital ulcer resistant to conventional therapy, treated successfully with Hyperbaric Oxygen Therapy. The application of hyperbaric oxygen, which is used for the treatment of ischemic ulcers, is an effective and safe therapeutic option in patients with ischemic vasculitic ulcers in combination with immunosuppressive drugs. Further studies are needed to evaluate its role as primary therapy for this group of patients.

The relationship between either heart rate or diastolic time and ST segment depression has been evaluated during supine and upright exercise in 16 coronary artery disease patients. Diastolic perfusion time and ST segment depression were related by a linear regression, which was independent of exercise posture. The entity of ST segment depression was greater during supine than in upright exercise for the same heart rate. The assessment of the relationship between heart rate and diastolic perfusion time during two exercises showed that at the same heart rate, diastolic perfusion time was shorter in supine posture. In conclusion, the greater entity of ST segment depression induced by supine rather than upright exercise might be explained by the effect of supine posture on diastolic perfusion time.

The lipophilic probe 1,6-diphenyl-1,3,5-hexatriene was incorporated into erythrocyte ghosts of either normal or obese humans, and the polarization of fluorescence was measured between 0 and 40 C. The membrane lipid fluidity, evaluated by fluorescence polarization, was consistently higher in the ghosts from obese subjects. A strong correlation was found between increased 1,6-diphenyl-1,3,5-hexatriene fluorescence polarization and excess body weight. Measurements of cholesterol and phospholipids indicated increased cholesterol and decreased phospholipids in erythrocyte ghosts from obese subjects. These data suggest that alterations in lipid composition in erythrocytes of obese subjects are responsible for abnormal physical properties of plasma membranes, which, in turn, may cause altered enzymatic activities.

The mitogenic effect of thyrotropin on functional rat thyroid cells of the line FRTL-5 is correlated with membrane lipid fluidity as evaluated by fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene. Continued exposure of FRTL-5 cells to a medium lacking thyrotropin causes cessation of cell proliferation and a decrease in membrane lipid fluidity which reaches its minimum in approximately 8 days. The change in lipid fluidity is due to an absolute increase (greater than 2-fold) of membrane cholesterol, with an increased cholesterol/phospholipid ratio and an increased ratio of saturated to unsaturated fatty acids of the membrane phospholipids, contributed primarily by a nearly 4-fold increase in the ratio of saturated to unsaturated C16 fatty acids. It is also associated with a variation of the relative proportions of the major membrane phospholipids; thus, phosphatidylinositol and phosphatidylethanolamine decrease while phosphatidylcholine increases. Both membrane fluidity and lipid composition can be restored by thyrotropin to their original levels, i.e. levels measured under continuous exposure to the hormone. Complete reversal requires at least 48 h, i.e. approximately the same time required for resumption of growth when FRTL-5 cells, starved in thyrotropin, are re-exposed to the hormone. Changes in lipid composition and fluidity can be prevented or can be reversed if FRTL-5 cells are exposed to dibutyryl cAMP while being deprived of thyrotropin. Dibutyryl cAMP has only a modest direct effect on growth; however, this pretreatment eliminates the 48-h lag phase with respect to thyrotropin stimulation. It is proposed that the effects of thyrotropin on growth of FRTL-5 cells requires a modification of the molecular structure and the physical state of cell membranes, which can be mediated by cAMP, although cAMP is not sufficient by itself to promote growth.

Diastolic perfusion time is a critical determinant of myocardial oxygen supply when coronary artery flow is limited by a significant stenosis of the coronary vessel. Diastolic time adjustment of the ST segment depression occurring during effort enhances stress test prediction of the coronary impairment severity. Effective diastolic adjustment of ST segment requires a stable and simple to perform measurement of the diastolic perfusion time during stress test execution. The authors investigated the reproducibility of the diastolic measurements obtained using the arterial pulse of the lobulus auriculae compared to the classical phonocardiographic data. The results obtained indicate that ear arterial pulse measurement of the diastolic time is reliable avoiding the difficulties rising from using the phonocardiographic method.