Catheter Ablation of Electrical Storm Due to Monomorphic Ventricular Tachycardia in Patients with Nonischemic Cardiomyopathy: Acute Results and Its Effect on Long‐Term Survival

Background: Electrical storm due to recurrent ventricular tachycardia (VT) in patients with implantable cardioverter defibrillator (ICD) can adversely affect their long‐term survival. This study evaluates the efficiency of the radiofrequency catheter ablation of electrical storm due to monomorphic VT in patients with idiopathic dilated cardiomyopathy (DCM) and assesses its long‐term effects on survival. Methods and Results: Between April 2004 and October 2008, 13 consecutive patients (nine men, mean age 56.8 ± 17.8 years) with DCM and electrical storm due to monomorphic VT who had ICD underwent 17 catheter ablation procedures, including four epicardial, at our center. Acute complete success was defined as the lack of inducibility of any VT at the end of procedure during programmed right ventricular stimulation and was achieved in eight patients (61.5%). During a median follow‐up of 23 months (range 3–63 months) nine patients (69%) were alive and eight patients (61.5%) were free from VT recurrence. Among those with acute complete (n = 8) and partial (n = 5) success, seven patients (87.5%) and one patient (20%) were free from any VT recurrence and ICD therapy, respectively (P = 0.025). Among those with acute complete and partial success, seven patients (87.5%) and two patients (40%) were alive, respectively (Mantel‐Cox test P = 0.082). Among those who had an initially failed endocardial ablation (n = 8), four underwent further epicardial ablation that was completely successful in three patients (75%). Conclusion: Catheter ablation in patients with DCM and electrical storm due to monomorphic VT who had an ICD prevents further VT recurrence in 61.5% of the patients. Complete successful catheter ablation may play a protective role and was associated with reduced mortality during the follow‐up period. More aggressive ablation strategies in patients with initially failed endocardial ablation might improve the long‐term survival of these patients; however, further studies are needed to clarify this issue. (PACE 2010; 33:1504–1509)     

Catheter Ablation of Scar‐Related Ventricular Tachycardia in Patients with Electrical Storm Using Remote Magnetic Catheter Navigation

Background: A remote magnetic navigation system (MNS) has been used for ablation of ventricular arrhythmias. However, irrigated tip catheter has not been evaluated in large series of patients. Objective: To evaluate acute and long‐term efficiency of the newly available irrigated tip magnetic catheter for radiofrequency (RF) ablation of scar‐related ventricular tachycardia (VT) in patients with ischemic heart disease. Methods: Between January 2008 and October 2009, a total of 30 consecutive patients with ischemic heart disease (26 men, age 70.1 ± 8.7 years, left ventricular ejection fraction: 30 ± 9%) and electrical storm due to monomorphic VT underwent RF ablation using a remote MNS and a magnetic irrigated tip catheter. Results: Acute success was defined as noninducibility of any monomorphic VT during programmed right and left ventricular stimulation, and obtained in 24 (80%) patients. A total of 1–6 VTs (mean 2.3 ± 1.2, 394 ± 108 ms, 210–660 ms) were inducible during each procedure. The duration of RF energy application was 41.2 ± 23.3 minutes, with total procedure and fluoroscopy times of 158 ± 47 minutes and 9.8 ± 5.3 minutes, respectively. No acute complications were observed during the procedures. During mean follow‐up of 7.8 months, 21 patients (70%) had no recurrence of VT and received no implantable cardioverter defibrillator therapy. Among patients who were noninducible during programmed right ventricular stimulation (n = 25), ≥1 monomorphic VT was inducible during programmed left ventricular stimulation in four (16%) that was ablated successfully in three of them. Conclusions: Irrigated ablation of scar‐related VT using remote MNS is an effective modality for management of the monomorphic VT in patients with ischemic cardiomyopathy with minimal radiation exposure. Programmed left (in addition to right) ventricular stimulation might be necessary to assess acute outcome of the ablation procedure. (PACE 2010; 1312–1318)     

Prevalence and predictors for post‐thrombotic syndrome 3 to 16 years after pregnancy‐related venous thrombosis: a population‐based,cross‐sectional,case‐control study

Background:  The long‐term outcome of pregnancy‐related venous thrombosis (VT) is not known. Objectives:  To assess predictors and long‐term frequency of post‐thrombotic syndrome (PTS) after pregnancy‐related VT. Patients/Methods:  In 2006, 313 women with pregnancy‐related VT during 1990–2003 and 353 controls answered a comprehensive questionnaire that included self‐reported Villalta score as a measure of PTS. Cases were identified from 18 Norwegian hospitals using the Norwegian Patient Registry and the Medical Birth Registry of Norway. The latter was used to select as possible controls women who gave birth at the same time as a case. Thirty‐nine patients and four controls were excluded because of VT outside the lower limbs/lungs or missing Villalta scores. Two hundred and four patients had DVT in the lower limb and 70 had pulmonary embolism (PE). The control group comprised 349 women naive for VT at the time of the index pregnancy. Results:  Forty‐two per cent of cases with DVT in the lower limb, compared with 24% of cases with PE and 10% of controls, reported a Villalta score of ≥ 5. Severe PTS (Villalta score of ≥ 15) was reported among 7%, 4% and 1%. Proximal postnatal, but not antenatal, thrombosis was a strong predictor of PTS with an adjusted odds ratio of 6.3 (95% confidence interval, 2.0–19.8; P = 0.002). Daily smoking before the index pregnancy and age above 33 years at event were independent predictors for post‐thrombotic syndrome. Conclusions:  PTS is a common long‐term complication after pregnancy‐related DVT. Proximal postnatal thrombosis, smoking and higher age were independent predictors of the development of PTS.     

The risk of venous thrombosis in women over 50 years old using oral contraception or postmenopausal hormone therapy

Roach REJ, Lijfering WM, Helmerhorst FM, Cannegieter SC, Rosendaal FR, van Hylckama Vlieg A. The risk of venous thrombosis in women over 50 years old using oral contraception or postmenopausal hormone therapy. J Thromb Haemost 2013; 11 : 124–31. Summary. Background: Oral contraception (OC) and postmenopausal hormone therapy (HT) can be used to alleviate menopausal symptoms. However, the risk of venous thrombosis (VT) associated with OC use in women over 50 years old has never been assessed and the two preparations have not been directly compared. Objectives: To determine and compare the risk of VT associated with OC and HT use. Methods: From a large case–control study, 2550 women aged over 50 years old, 1082 patients with a first VT and 1468 controls, were included. Odds ratios (ORs) and 95% confidence intervals for VT were calculated for OC‐users (164 patients and 54 controls) and HT‐users (88 patients and 102 controls) compared with non‐hormone users (823 patients and 1304 controls). Results: OC‐users had a 6.3‐fold (4.6–9.8) increased risk of VT. This ranged from 5.4 (3.3–8.9) for preparations containing levonorgestrel to 10.2 (4.8–21.7) for desogestrel. The VT‐risk associated with oral HT use was 4.0 (1.8–8.2) for conjugated equine estrogen combined with medroxyprogesterone acetate and 3.9 (1.5–10.7) for micronized estradiol combined with norethisterone acetate. Non‐oral HT did not increase the risk of VT: OR 1.1 (0.6–1.8). Relative risk estimates were further increased in hormone users with factor V Leiden, prothrombin G20210A or blood group non‐O and hormone users with a family history of VT. Conclusions: In this study, non‐oral HT seemed to be the safest hormonal preparation in women over 50 years old. OC use increased the VT risk the most, especially in women with inherited thrombophilia or a family history of VT.     

Ablation of Post‐Myocardial Infarction Focal Ventricular Tachycardia

In the chronic phase of myocardial infarction, the presence of scar areas allows the development of macro‐reentries which become the most frequent mechanism underlying ventricular tachycardia (VT). A focal mechanism has been already described in the presence of scar in animal models or in humans but only during surgery. We report a case of focal automatic VT arising from postinfarction scar fibrosis, successfully mapped and ablated during an electro‐physiological procedure. (PACE 2010; 904–906)     

High‐Resolution Optical Mapping of Ventricular Tachycardia in Rats with Chronic Myocardial Infarction

Background: Ventricular tachycardia (VT) is a common cause of mortality in post‐myocardial infarction (MI) patients, even in the current era of coronary revascularization treatment. We report a reproducible VT model in rats with chronic MI induced by ischemia‐reperfusion and describe its electrophysiological characteristics using high‐resolution optical mapping. Methods: An MI was generated by left anterior descending coronary ligation (25 minutes) followed by reperfusion in 20 rats. Electrophysiology study and optical mapping were performed 5 weeks later using a Langendorff‐perfused preparation and compared to normal rats. Results: The conduction velocity of the MI border zone was decreased to 53% of the normal areas remote from the infarct (0.37 ± 0.16 m/sec vs 0.70 ± 0.09 m/sec, P < 0.0001). The rate of VT inducibility in MI rats was significantly greater than in normal control rats (70% vs 0%, P = 0.00002). VT circuits involving the infarct area were identified with optical mapping in 83% MI rats. In addition, fixed and functional conduction block were observed in the infarct border zone. Conclusion: This ischemia‐reperfusion MI rat model is a reliable VT model, which simulates clinical revascularization treatment. High‐resolution optical mapping in this model is useful to study the mechanism of VT and evaluate the effects of therapies. (PACE 2010; 33:687–695)     

A Nonfluoroscopic Technique for Coronary Arteries Three‐Dimensional Mapping during Epicardial Ventricular Tachycardia Ablation

When performing epicardial ablation of ventricular tachycardia (VT), caution must be taken not to damage the coronary arteries. We report a case in which a new, nonfluoroscopic technique for incorporating an accurate, real‐time reconstruction of the main coronary vessels into a three‐dimensional electroanatomic map was used for epicardial VT ablation.     

Procainamide and Survival in Ventricular Fibrillation Out‐of‐hospital Cardiac Arrest

Objectives: Procainamide is an antiarrhythmic drug of unproven efficacy in cardiac arrest. The association between procainamide and survival from out‐of‐hospital cardiac arrest was investigated to better determine the drug’s potential role in resuscitation. Methods: The authors conducted a 10‐year study of all witnessed, out‐of‐hospital, ventricular fibrillation (VF) or pulseless ventricular tachycardia (VT) cardiac arrests treated by emergency medical services (EMS) in King County, Washington. Patients were considered eligible for procainamide if they received more than three defibrillation shocks and intravenous (IV) bolus lidocaine. Four logistic regression models were used to calculate odds ratios (ORs) and 95% confidence intervals (CI) describing the relationship between procainamide and survival. Results: Of the 665 eligible patients, 176 received procainamide, and 489 did not. On average, procainamide recipients received more shocks and pharmacologic interventions and had lengthier resuscitations. Adjusted for their clinical and resuscitation characteristics, procainamide recipients had a lower likelihood of survival to hospital discharge (OR = 0.52; 95% CI = 0.36 to 0.75). Further adjustment for receipt of other cardiac medications during resuscitation negated this apparent adverse association (OR = 1.02; 95% CI = 0.66 to 1.57). Conclusions: In this observational study of out‐of‐hospital VF and pulseless VT arrest, procainamide as second‐line antiarrhythmic treatment was not associated with survival in models attempting to best account for confounding. The results suggest that procainamide, as administered in this investigation, does not have a large impact on outcome, but cannot eliminate the possibility of a smaller, clinically relevant effect on survival. ACADEMIC EMERGENCY MEDICINE 2010; 17:617–623 © 2010 by the Society for Academic Emergency Medicine     

Protective effect of fenofibrate against ischemia‐/reperfusion‐induced cardiac arrhythmias in isolated rat hearts

Fenofibrate is a peroxisome proliferator‐activated receptor (PPAR)‐α activator that lowers triglycerides and influences cytochrome P‐450 (CYP‐450) epoxygenase‐dependent arachidonic acid (AA) metabolism. CYP‐450 epoxygenase metabolizes AA to epoxyeicosatrienoic acids (EETs). EETs have coronary dilating and cardiac and renal protective properties. Fibrates possess similar properties due to their CYP‐450 epoxygenase‐inducing properties that lead to increase in endogenous EET production. In the current investigations, fenofibrate (100 mg/kg, orally) for 2 weeks decreased ischemia‐/reperfusion (I/R)‐induced premature ventricular contractions (PVCs), ventricular tachycardia (VT), and ventricular fibrillation (VF) in the isolated rat hearts. Fenofibrate caused marked inhibition of the reperfusion‐induced cardiac arrhythmias. The incidence of reperfusion‐induced VF decreased from 80% in the control vehicle‐treated animals to 33% in the fenofibrate‐treated animals (P < 0.001). PVCs were also significantly (P < 0.01) decreased from 223.2 ± 51 in control vehicle‐treated animals to 136.8 ± 22 in fenofibrate‐treated animals. Total duration of reperfusion‐induced VT decreased from 29.2 ± 6.3 s in control, vehicle‐treated animals to 4.8 ± 1.3 s in fenofibrate‐treated animals, P < 0.001. Heart rate and perfusion pressure were not significantly affected by fenofibrate pretreatment. Diltiazem, a clinically used anti‐arrhythmic agent, produced complete protection against I/R‐induced cardiac arrhythmias in this model reducing the incidence of VF from 80% in control, vehicle‐treated animals to 10% in diltiazem‐treated hearts. These findings indicate that fenofibrate suppresses arrhythmias in isolated rat hearts subjected to I/R‐induced injury.     

Stereotactic body radiation therapy for refractory ventricular tachycardia secondary to cardiac lipoma: A case report

We present the case of a 29‐year‐old man who developed ventricular tachycardia (VT) secondary to a cardiac lipoma located adjacent to the interventricular groove, which could not be fully resected. Antiarrhythmic drugs and endocardial and epicardial ablation failed to prevent VT recurrence. Finally, noninvasive stereotactic body radiation therapy (SBRT) targeting the lipoma was performed, with a total dose of 24 Gy delivered in three fractions. The number of VT episodes was reduced from 189/24 h before SBRT to 0 after the procedure. At 4‐month follow‐up, there were no signs of therapy‐related complications. Our experience suggests that SBRT could emerge as a viable treatment option for patients with cardiac tumors who develop refractory ventricular arrhythmias.     

Basal Exit Site of Clinical Ventricular Tachycardia is an Independent Predictor of Antitachycardia Pacing Failure in Implantable Cardioverter‐Defibrillators Recipients

Background: Little is known about predictors of antitachycardia pacing (ATP) failure in implantable cardioverter defibrillator (ICD) recipients. Distance between the stimulation site and the ventricular tachycardia (VT) site of origin may critically affect ATP effectiveness. We hypothesized that ATP may be less effective in ICD patients who had basal VT than in those who had apical VT. Methods: We reviewed data from 52 patients with sustained monomorphic VT and left ventricular disease referred for ICD implantation. ATP was delivered exclusively at the right ventricular apex. The clinical VTs site of origin (basal, midventricular, or apical) was determined in each patient, using 12‐lead electrocardiogram. VTs episodes treated with ATP during the 1‐year follow‐up were studied. ATP success rate (%), defined as the ratio between the number of successful ATP sequences and the number of delivered ATP sequences, was determined in each patient. Results: VT exit site was apical in 19 patients (36%), basal in 18 patients (35%), and midventricular in 15 patients (29%). In those 52 patients, 1,393 ATP sequences, delivered to treat 761 VT episodes, were analyzed. ATP success rate was found to be associated with the VT site of origin (median [interquartile range]): basal (33%[11–67]), midventricular (50%[37–100]), apical (100%[41–100]) (P = 0.027). Multivariate analysis identified basal VT site of origin as an independent predictor of ATP failure (P = 0.023). Conclusion: ATP is less effective in ICD patients who had basal VT than in those who had apical VT before ICD implantation. (PACE 2012; 35:1209–1216)     

Could SF‐36 be used as a screening instrument for depression in a Swedish youth population?

Scand J Caring Sci; 2011; 25; 262–268
Could SF‐36 be used as a screening instrument for depression in a Swedish youth population? Objective: Depression among youth is a condition associated with serious long‐term morbidity and suicide. The aim of this study was to investigate whether a HRQoL instrument, the short form 36 version 1.0 (SF‐36), could be used to screen for depression in a clinical Youth Centre (YC). A second purpose was to describe self‐reported health and depression. Setting: A clinical YC at a University hospital. Design: A sample of 660 youths, 14–20 years old was assessed with SF‐36 and Montgomery Åsberg Depression Rating Scale, self‐screening version (MADRS‐S). Answers to all the questions in both instruments were given by 79% (519/660; 453 women and 66 men). Mean age in the sample was 17.5 ± 1.6 years. Results: Strong correlations were found between all the SF‐36 subscales and the depression ratio scale MADRS‐S. Receiver operating characteristic (ROC) curve analysis confirmed that the SF‐36 subscales mental health (MH) and vitality (VT) could correctly predict depression on the individual level with Area Under the ROC Curve values 0.87 and 0.84 in ROC curves. Individuals scoring 48 or lower on MH and 40 or lower on VT should be followed up with a clinical interview concerning possible depressive disorder. Mild to moderate depression was common (35.5%), especially among women (37.5%). Men scored higher than women on all SF‐36 subscales except for physical functioning. Conclusions: The SF‐36 can be used to screen for suspect depression in a youth population followed by interview. This gives an opportunity to detect and treat emerging depressive symptoms early.     

Lentivirus‐mediated platelet gene therapy of murine hemophilia A with pre‐existing anti‐factor VIII immunity

Summary. Background: The development of inhibitory antibodies, referred to as inhibitors, against exogenous factor VIII in a significant subset of patients with hemophilia A remains a persistent challenge to the efficacy of protein replacement therapy. Our previous studies using the transgenic approach provided proof‐of‐principle that platelet‐specific expression could be successful in treating hemophilia A in the presence of inhibitory antibodies. Objective: To investigate a clinically translatable approach for platelet gene therapy of hemophilia A with pre‐existing inhibitors. Methods: Platelet FVIII expression in preimmunized FVIII^null mice was introduced by transplantation of lentivirus‐transduced bone marrow or enriched hematopoietic stem cells. FVIII expression was determined with a chromogenic assay. The transgene copy number per cell was quantitated with real‐time PCR. Inhibitor titer was measured with the Bethesda assay. Phenotypic correction was assessed by the tail clipping assay and an electrolytically induced venous injury model. Integration sites were analyzed with linear amplification‐mediated PCR. Results: Therapeutic levels of platelet FVIII expression were sustained in the long term without evoking an anti‐FVIII memory response in the transduced preimmunized recipients. The tail clip survival test and the electrolytic injury model confirmed that hemostasis was improved in the treated animals. Sequential bone marrow transplants showed sustained platelet FVIII expression resulting in phenotypic correction in preimmunized secondary and tertiary recipients. Conclusions: Lentivirus‐mediated platelet‐specific gene transfer improves hemostasis in mice with hemophilia A with pre‐existing inhibitors, indicating that this approach may be a promising strategy for gene therapy of hemophilia A even in the high‐risk setting of pre‐existing inhibitory antibodies.     

Risk of venous thrombosis in pregnancy among carriers of the factor V Leiden and the prothrombin gene G20210A polymorphisms

Background: Pregnancy is associated with a 10‐fold increased risk of venous thrombosis (VT), with different risk profiles for the antenatal and postnatal periods. The purpose of this study was to assess the risk of pregnancy‐related VT associated with the factor (F)V Leiden and prothrombin gene G20210A polymorphisms. Materials and Methods: The study comprised 377 155 women with 613 232 pregnancies at 18 Norwegian hospitals from 1 January 1990 to 31 December 2003. Of a total 559 cases with a validated first lifetime diagnosis of VT in pregnancy or within 14 weeks postpartum, and 1229 controls naive for VT, 313 cases and 353 controls donated biological material. Results: The odds ratios for VT during pregnancy or puerperium were 5.0 [95% confidence interval (CI) 3.1–8.3] and 9.4 (95% CI 2.1–42.4) for heterozygous carriers of the FV Leiden and the prothrombin gene polymorphisms, respectively. All homozygous carriers of the FV Leiden polymorphism (n = 8) and the prothrombin polymorphism (n = 1) developed VT, indicating a very high risk of VT. We estimated that pregnancy‐related VT occurred in 1.1/1000 non‐carriers, in 5.4/1000 heterozygous carriers of the FV Leiden polymorphism, and in 9.4/1000 heterozygous carriers of the prothrombin polymorphism. To avoid one VT, the number of pregnant women needed to be screened for these two polymorphisms and the number needed to be given thromboprophylaxis were 2015 and 157, respectively. Conclusions: Although the relative risk for VT during pregnancy and after delivery was increased among carriers of the FV Leiden and the prothrombin polymorphisms, the overall probability for pregnancy‐related VT was low.     

A Historical Perspective on the Role of Functional Lines of Block in the Re‐entrant Circuit of Ventricular Tachycardia

The ablation strategy for ventricular tachycardia (VT) rapidly evolved from an entrainment mapping approach for identification of the critical isthmus of the re‐entrant circuit during monomorphic VT, toward a substrate‐based approach aiming to ablate surrogate markers of the circuit during sinus rhythm in hemodynamically nontolerated and polymorphic VT. The latter approach implies an assumption that the circuits responsible for the arrhythmia are anatomical or fixed, and present during sinus rhythm. Accordingly, the lines of block delimiting the channels of the circuits are often considered fixed, although there is evidence that they are functional or more frequently a combination of fixed and functional. The electroanatomical substrate‐based approach to VT ablation performed during sinus rhythm is increasingly adopted in clinical practice and often described as scar homogenization, scar dechanneling, or core isolation. However, whether the surrogate markers of the VT circuit during sinus rhythm match the circuit during arrhythmias remains to be fully demonstrated. The myocardial scar is a heterogeneous electrophysiological milieu with complex arrhythmogenic mechanisms that potentially coexist simultaneously. Moreover, the scar consists of different areas of diverse refractoriness and conduction. It can be misleading to limit the arrhythmogenic perspective of the myocardial scar to fixed or anatomical barriers held responsible for the re‐entry circuit. Greater understanding of the role of functional lines of block in VT and the validity of the surrogate targets being ablated is necessary to further improve the technique and outcome of VT ablation.     

Bilateral sympathectomy for treatment of refractory ventricular tachycardia

Ventricular tachycardia (VT) commonly occurs in patients with ischemic or nonischemic cardiomyopathy and requires antiarrhythmic drugs, ablation, or advanced circulatory support. However, life‐threatening VT may be refractory to these therapies, and may cause frequent implantable cardioverter defibrillator (ICD) discharges. Left cardiac sympathetic denervation reduces the occurrence of these fatal arrhythmias by inhibiting the sympathetic outflow to the cardiac tissue. We present a 69‐year‐old man with nonischemic cardiomyopathy, life‐threatening VT, and hemodynamic instability with numerous ICD discharges, who remained refractory to antiarrhythmic drug therapy and ablation attempts. He was effectively treated with bilateral cardiac sympathectomy. Six months later, he remained free of VT with no ICD discharges.     

Amiodarone or Procainamide for the Termination of Sustained Stable Ventricular Tachycardia: An Historical Multicenter Comparison

Objectives: The objective was to compare the effectiveness of intravenous (IV) procainamide and amiodarone for the termination of spontaneous stable sustained ventricular tachycardia (VT). Methods: A historical cohort study of consecutive adult patients with stable sustained VT treated with IV amiodarone or procainamide was performed at four urban hospitals. Patients were identified for enrollment by admissions for VT and treatment with the study agents in the emergency department (ED) from 1993 to 2008. The primary measured outcome was VT termination within 20 minutes of onset of study medicine infusion. A secondary effectiveness outcome was the ultimate need for electrical therapy to terminate the VT episode. Major adverse effects were tabulated, and blood pressure responses to medication infusions were compared. Results: There were 97 infusions of amiodarone or procainamide in 90 patients with VT, but the primary outcome was unknown after 14 infusions due to administration of another antidysrhythmic during the 20‐minute observation period. The rates of VT termination were 25% (13/53) and 30% (9/30) for amiodarone and procainamide, respectively. The adjusted odds of termination with procainamide compared to amiodarone was 1.2 (95% confidence interval [CI] = 0.4 to 3.9). Ultimately, 35/66 amiodarone patients (53%, 95% CI = 40 to 65%) and 13/31 procainamide patients (42%, 95% CI = 25 to 61%) required electrical therapy for VT termination. Hypotension led to cessation of medicine infusion or immediate direct current cardioversion (DCCV) in 4/66 (6%, 95% CI = 2 to 15%) and 6/31 (19%, 95% CI = 7 to 37%) patients who received amiodarone and procainamide, respectively. Conclusions: Procainamide was not more effective than amiodarone for the termination of sustained VT, but the ability to detect a significant difference was limited by the study design and potential confounding. As used in practice, both agents were relatively ineffective and associated with clinically important proportions of patients with decreased blood pressure. ACADEMIC EMERGENCY MEDICINE 2010; 17:297–306 © 2010 by the Society for Academic Emergency Medicine     

Termination of ventricular tachycardia by far-field stimulation in humans: a feasibility study

Background: Although a low‐energy cardioversion (LEC) shock from an implantable cardioverter‐defibrillator (ICD) can terminate ventricular tachycardia (VT), it frequently triggers ventricular fibrillation (VF) and is therefore not used in clinical practice. We tested whether a modified LEC shock with a very short duration (0.12–0.36 ms), termed “field stimulus,” can terminate VT without triggering VF. Methods: In 13 sedated patients with implanted ICDs, we attempted to induce VT and to terminate the arrhythmias by field stimuli during hospital predischarge tests. Results: In eight patients, 27 VT episodes were induced and treated with a total of 46 high‐voltage (25–200 V) field stimuli, which terminated 11 VT episodes (41% efficacy) and never accelerated VT into VF. VT episodes slower than 230 beats per minute (bpm) (median rate) were terminated more successfully than faster arrhythmia episodes (69% vs 15%, P < 0.01). The strength of the field stimulus had no major influence on the effectiveness. We therefore postulate that suboptimal timing of field stimuli (delivered simultaneously with a sensed event in the right ventricular apex) was the main reason for failed VT terminations. Conclusion: A short (0.12–0.36 ms), high‐voltage (50–100 V) field stimulus delivered from the shock coil of an implanted ICD system can safely terminate VT, especially for VT rates below 230 bpm. We believe that it would be reasonable to test the effectiveness of automatic field‐stimulus therapy from implanted ICDs in VT episodes up to 230 bpm that are not susceptible to termination by antitachycardia pacing. (PACE 2010; 33:1540–1547)     

Inappropriate disabling of an ICD noise‐detection algorithm in pacemaker‐dependent patients

SecureSense is an implantable cardioverter defibrillator algorithm that differentiates lead‐related oversensing from ventricular tachycardia/ventricular fibrillation by continuous comparison between the near‐field (NF) and the far‐field (FF) electrogram. If lead noise is identified, inappropriate therapy is withheld. Undersensing on the FF channel could result in inappropriate inhibition of life‐saving therapy. Thus, the device automatically switches SecureSense to passive mode if undersensing on the FF channel is suspected. We report here the first cases of inappropriate automatic SecureSense deactivation due to misdiagnosed FF undersensing in pacemaker‐dependent patients. Physicians should be aware that SecureSense does not withhold an inappropriate therapy for sustained oversensing in pacemaker‐dependent patients.     

Anti‐MDA‐5 antibody‐positive clinically amyopathic dermatomyositis with rapidly progressive interstitial lung disease treated with therapeutic plasma exchange: A case series

We present six cases of antimelanoma differentiation‐associated gene 5 antibody (anti‐MDA5‐Ab)‐positive clinically amyopathic dermatomyositis (CADM) with rapidly progressive interstitial lung disease (RP‐ILD), which is known to have a poor prognosis. The outcomes of these cases are described after treatment with therapeutic plasma exchange (TPE). Clinical and therapeutic data for patients with CADM with RP‐ILD were collected retrospectively from medical records. All six patients received early intensive care including high‐dose corticosteroids, intravenous cyclophosphamide, and a calcineurin inhibitor, but lung disease and hypoxia became more severe. TPE was performed over a median of 9.5 sessions (range 3‐14) per patient, and the median duration from admission to TPE was 23 days. Three patients received combined direct hemoperfusion using a polymyxin B‐immobilized fiber column (PMX‐DHP) therapy on successive days to manage acute respiratory failure. Four patients survived and two died due to respiratory failure. In the survival cases, ferritin decreased, and ferritin and KL‐6 were lower at diagnosis. The patients who died had a higher alveolar‐arterial oxygen difference and more severe lung lesions at the time of initiation of TPE. These findings indicate that a combination of conventional therapy and TPE may be useful for improvement of the prognosis of CADM with RP‐ILD at the early stage of onset.