Background The prevalence of patent foramen ovale among patients with cryptogenic stroke is higher than that in the general population. Closure with a percutaneous device is often recommended in such patients, but it is not known whether this intervention reduces the risk of recurrent stroke. Methods We conducted a multicenter, randomized, open-label trial of closure with a percutaneous device, as compared with medical therapy alone, in patients between 18 and 60 years of age who presented with a cryptogenic stroke or transient ischemic attack (TIA) and had a patent foramen ovale. The primary end point was a composite of stroke or transient ischemic attack during 2 years of follow-up, death from any cause during the first 30 days, or death from neurologic causes between 31 days and 2 years. Results A total of 909 patients were enrolled in the trial. The cumulative incidence (Kaplan– Meier estimate) of the primary end point was 5.5% in the closure group (447 patients) as compared with 6.8% in the medical-therapy group (462 patients) (adjusted hazard ratio, 0.78; 95% confidence interval, 0.45 to 1.35; P = 0.37). The respective rates were 2.9% and 3.1% for stroke (P = 0.79) and 3.1% and 4.1% for TIA (P = 0.44). No deaths occurred by 30 days in either group, and there were no deaths from neurologic causes during the 2-year follow-up period. A cause other than paradoxical embolism was usually apparent in patients with recurrent neurologic events. Conclusions In patients with cryptogenic stroke or TIA who had a patent foramen ovale, closure with a device did not offer a greater benefit than medical therapy alone for the prevention of recurrent stroke or TIA. (Funded by NMT Medical; ClinicalTrials.gov number, NCT00201461.)

/pdf/closure-or-medical-therapy-for-cryptogenic-stroke-with-1swlkx59yn.pdf

Closure or Medical Therapy for Cryptogenic Stroke with Patent Foramen Ovale

Background
Atrial fibrillation is the most frequent sustained arrhythmia. Atrial fibrillation often recurs after restoration of normal sinus rhythm. Antiarrhythmic drugs have been widely used to prevent recurrence. This is an update of a review previously published in 2006, 2012 and 2015.

/pdf/antiarrhythmics-for-maintaining-sinus-rhythm-after-4uam1xpsla.pdf

Antiarrhythmics for maintaining sinus rhythm after cardioversion of atrial fibrillation

Vasospasm, its Role in the Pathogenesis of Diseases with Particular Reference to the Eye

Implantable electrodes for defibrillation are formed of pluralities of electrode segments. Each of the segments is relatively long and narrow. The electrode segments can be parallel and spaced apart from one another a distance at least ten times the nominal width, with one end of each segment mounted to a transverse distal portion of an electrically conductive lead coupling the electrode to a defibrillation pulse generator. Alternatively, segments can branch or radiate outwardly from a common junction. In yet another arrangement, electrode segments are portions of a single conductive path at the distal end of a lead from a pulse generator, arranged in either a spiral configuration or a serpentine configuration which can align electrode segments side by side, parallel and spaced apart. The electrode segments can be formed of composite conductors in the form of titanium ribbons or wires with a sputtered outer layer of platinum, or a silver core in a stainless steel tube, with a platinum layer formed onto the tube. The electrodes are highly compliant yet can provide large effective areas for defibrillation, enabling a transthoracic pulsing arrangement of two electrodes on opposite sides of the heart, implanted subcutaneously outside of the thoracic region.

Body implantable defibrillation system

A reduction in the shock strength required for defibrillation would allow use of a smaller automatic implantable cardioverter-defibrillator and would reduce the possibility of myocardial damage by the shock. Most internal defibrillation electrodes require 5 to 25 J for successful defibrillation in human beings and in dogs. In an attempt to lower the shock strength needed for defibrillation, we designed two large titanium defibrillation patch electrodes that were contoured to fit over the right and left ventricles of the dog heart, covering areas of approximately 33 and 39 cm2, respectively. In six anesthetized open-chest dogs, the electrodes were secured directly to the epicardium and ventricular fibrillation was induced by 60 Hz alternating current. Truncated exponential monophasic and biphasic shocks were given 10 sec later and defibrillation thresholds (DFTs) were determined. The DFT was 159 +/- 48 V, 3.2 +/- 1.9 J (mean +/- SD) for 10 msec monophasic shocks and 106 +/- 22 V, 1.3 +/- 0.4 J, for biphasic shocks with both phase durations equal to 5 msec (5-5 msec). The experiment was repeated in another six dogs in which the electrodes were secured to the pericardium. The mean DFT was not significantly higher than that for the electrodes on the epicardium: 165 +/- 27 V, 3.1 +/- 1.2 J for 10 msec monophasic shocks and 116 +/- 19 V, 1.6 +/- 0.5 J for 5-5 msec biphasic shocks. Low DFTs were also obtained with biphasic shocks in which the duration of the first phase was longer than that of the second.(ABSTRACT TRUNCATED AT 250 WORDS)

Improved defibrillation thresholds with large contoured epicardial electrodes and biphasic waveforms.

We compared the prevalence of patent foramen ovale (PFO), detected by two-dimensional contrast echocardiography, in a group of 60 adults aged under 55 who had experienced a cerebral ischaemic accident and had normal standard examination of the heart, and in a control group of 100 patients. The prevalence of PFO was significantly higher in neurological patients (40 p. 100) than in controls (10 p. 100; p less than 0.001). Within the neurological group, the prevalence of PFO determined blindly, i.e. without any knowledge of the aetiological diagnosis, increased with the uncertainty of diagnosis: 21 p. 100 when a cause could be determined (n = 19), 40 p. 100 when a facilitating factor of cerebral accident, such as mitral valve prolapse, migraine or consumption of oral contraceptives, could be identified (n = 15), and 54 p. 100 when neither cause nor facilitating factor could be found (n = 26; p less than 0.10). In view of the very high prevalence of clinically silent venous thrombosis, these results suggest that paradoxical embolism through a PFO might be responsible for cerebral ischaemic accidents more frequently than is generally believed.

Prevalence of patent foramen ovale in young patients with ischemic cerebral complications

Endocavitary catheter ablation is a new method of treating cardiac arrhythmias. It may be used indirectly, interrupting conduction through the His bundle in supraventricular arrhythmias, or directly by altering the arrhythmogenic substrate to prevent ventricular tachycardia or fibrillation. We have observed, together with other workers, that changes in the electrical properties of the catheters used to deliver the endocavitary electrical discharge. This was unexpected as the shock was delivered through a unipolar electrode with the indifferent electrode placed on the patient's back. An analysis of the morphology of the discharge impulse in intensity and voltage at increasing energy values showed that the unconnected electrodes of the multi-electrode catheter were raised to approximately the same voltage as the indifferent electrode. The change in electrical properties of some catheters was therefore the result of an insulation defect between the conducting wires leading to the electrodes. A study of the rupturing voltage of 32 USCI endocavitary catheters showed that 5 were able to sustain repeated shocks of 2 Kv and that 3 were able to sustain 3.5 Kv. The insulation of Cordis catheters was good but problems were encountered due to the resistance of the wires leading to the electrodes which dissipated an abnormally high amount of energy, so reducing the energy actually reaching the myocardium. These observations may explain the inconsistency of results obtained by different groups performing endocavitary catheter ablation with material not designed specifically for this purpose.

Endocavitary electric shock. Problems related to equipment

The role of endothelin, a powerful vasoconstrictor, was studied in coronary spasm. A methylergonovine stress test was performed in patients with normal coronary angiography. Patients who developed spasm (Group I, n = 6) were compared with those who did not (Group II, n = 6). Plasma endothelin was measured at 8, 11 a.m., 2 p.m., 4, 7, 9, 11 p.m. and 1 a.m. The stress test was carried out at 17 hours and an additional endothelin measurement was performed during spasm in positive cases. The clinical characteristics of the two groups were comparable especially with regards to cardiovascular risk factors. Except for the value recorded during coronary spasm, the plasma endothelin levels were significantly higher in the group with coronary spasm. A time-dependent variation was observed in both groups with higher endothelin levels in the morning. In group I the plasma endothelin levels were higher under basal conditions and during spasm in patients with spastic angina.

Changes in plasma endothelin during coronary spasm

Chez le chien normal nous avons etudie le seuil de defibrillation apres induction de fibrillation ventriculaire par un courant alternatif Apres une periode de fibrillation soutenue de 10 secondes, des chocs d'energie progressivement croissante sont delivres Le systeeme d'electrode endocavitaire est capable d'une configuration unipolaire ou bipolaire; l'electrode distale se situe e l'apex du ventricule droit Les resultats suggerent que pour une capacite optimale de 9-20 uF, les chocs unipolaires (3-10j) sont plus efficaces que les chocs bipolaires (10-30j) En plus, des arrythmies diverses telles que la tachycardie ventriculaire rapide, le rythme idioventriculaire accelere et le bloc AV transitoire sont frequemment observees Nous concluons que: (1) un defibrillateur endocardique unipolaire et implantable semble faisable; (2) il devrait incorporer des circuits appropries pour le traitement des arrythmies observees apres choc



Defibrillation thresholds are studied in normal dog hearts after induction of ventricular fibrillation by alternating current Shocks of progressively increasing energies are tried after a period of 10 seconds of sustained ventricular fibrillation The endocardial electrode system may be either unipolar or bipolar, the distal electrode being situated at the right ventricular apex The results suggest that for an optimal capacitor in the range of 9-20 uF, unipolar shocks are more effective than bipolar shocks (3–10 versus 10–30 Joules) In addition, several cardiac arrhythmias, including rapid ventricular tachycardia, accelerated idioventricular rhythm, and transient AV block are frequently observed We conclude that (1) an implantable unipolar endocardial defibrillator seems feasible; and (2) the design should include the appropriate circuits to treat the arrhythmias observed after the shocks

Unipolar electrode system for an implantable defibrillator: new experimental approaches.

Comparison between the efficacy of amiodarone and quinidine in the treatment of atrial cardiac arrhythmias.

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