Prevalence, Therapeutic Response, and Outcome of Ventricular Tachycardia in the Out-of-hospital Setting: A Comparison of Monomorphic Ventricular Tachycardia, Polymorphic Ventricular Tachycardia, and Torsades de Pointes

OBJECTIVE: To investigate out-of-hospital ventricular tachycardia (VT) cardiac arrest patients, comparing the prevalences and outcomes of the following VT subtypes among this population: monomorphic VT (MVT), polymorphic VT (PVT), and torsades de pointes (TdP, PVT with a prolonged QT interval). METHODS: This was a retrospective review from a fire department-based paramedic system of nontraumatic VT cardiac arrest patients (January 1991 to December 1994) with a supraventricular perfusing rhythm (SVPR) at some time during out-of-hospital care, with a measurable QT interval. QT interval was measured from an SVPR, and corrected QT interval (QTc) was calculated and considered prolonged if > 0.45 sec. VT was classified as polymorphic or monomorphic. TdP was defined as PVT with a prolonged QT interval. RESULTS: 196 patients were identified; six were excluded due to incomplete medical records, leaving 190 who met inclusion criteria and were used for data analysis. 117 (62%) patients had MVT, while 73 (38%) patients had PVT; of the 73 patients with PVT, 37 (51%) had normal QTc (non-TdP PVT) and 36 (49%) had prolonged QTc (TdP PVT). 97 (51%) patients had prolonged QTc (PQTc). Regardless of VT type (i.e., MVT vs PVT), 97 (51%) patients had prolonged QTc, with a mean QTc of 0.476+/-0.15 seconds prearrest and 0.464+/-12 seconds postarrest. Patients with PQTc were not more likely to have PVT (70 [37%] vs 76 [40%]; p = 0.705). No significant difference with respect to paramedic-witnessed arrests in each VT morphology group and each QT group was found. The overall hospital discharge rate was 28.4%. Regardless of VT type, patients had similar rates of out-of-hospital return of spontaneous circulation (ROSC) and hospital discharge; patients with PQTc were less likely to be discharged from the hospital (19.6% vs 37.6%; p = 0.01). 27.8% of TdP and 26.8% of non-TdP patients were discharged (p = 0.912). CONCLUSIONS: In this population of out-of-hospital VT arrest patients, MVT is the most common form of VT encountered; PVT and the subtype TdP are also seen in this population with approximately equal frequencies. All three rhythm types demonstrate similar responses to standard Advanced Cardiac Life Support therapy with equal rates of out-of-hospital ROSC and hospital discharge. PQTc may be a marker of poor clinical outcome in patients with out-of-hospital VT arrest.     

Pharmacological Treatment of Electrical Storm in Cathecolaminergic Polymorphic Ventricular Tachycardia

We present a case of a young boy who had an implantable cadrioverter defibrillator implanted for refractory syncope and cathecolaminergic polymorphic ventricular tachycardia (CPVT). The patient underwent an electrical storm with multiple shocks and serious compromise of quality of life and risk. The pharmacological options are discussed as well as the strategies of managing ventricular arrhythmias in CPVT. (PACE 2010; 33:e27–e31)     

Amiodarone Induced Torsades de Pointes with Excessive QT Dispersion Following Quinidine Induced Polymorphic Ventricular Tachycardia

We report a case of amiodarone induced torsades de pointes (TdP) associated with increase QT dispersion in a patient with a history of quinidine induced TdP. An increase in QT dispersion of > 100% was noted on the 12 lead surface ECG postamiodarone therapy. In summary, amiodarone has a potential to induce TdP in patients with a previous history of quinidine induced TdP. QT dispersion could be a potential marker of TdP in these patients.     

Polymorphic Ventricular Tachycardia in a Woman Taking Cesium Chloride

SALIBA, W., et al. : Polymorphic Ventricular Tachycardia in a Woman Taking Cesium Chloride. A 47- year-old patient presented with syncope and recurrent episodes of polymorphic ventricular tachycardia. She had evidence of prolonged QT interval by ECG and had been taking cesium as a dietary supplement. Correction of the hypokalemia and discontinuation of the cesium resulted in normalization of the QT interval during follow-up with no further recurrence of ventricular arrhythmias. The use of this drug is potentially hazardous as it may induce fatal ventricular arrhythmias.     

Torsades de Pointes Ventricular Tachycardia Induced by Clarithromycin and Disopyramide in the Presence of Hypokalemia

We report a 76-year-Old woman who developed TdP ventricular tachycardia induced by combined use of clarithromycin and disopyramide. She had a history of myocardial infarction 5 years earlier and has taken disopyramide for supraventricular arrhythmias. In addition, she had taken clarithromycin for upper respiratory tract infection. On admission, an ECG showed prolongation of QTc interval to 0.71 seconds and self-terminating TdP occurred several times. Disopyramide was metabolized by the cytochrome enzyme CYP3A4 and clarithromycin competitively inhibits this enzyme, probably resulting in an increase in plasma concentration of disopyramide. We should consider this possibility when prescribing clarithromycin in combination with antiarrhythmic agent disopyramide.     

Torsades de Pointes: A Rare Complication of Temporary Pacing for Permanent Ventricular Pacemaker Failure

Torsades de pointes, a distinctive type of polymorphous ventricular tachycardia, may be induced by critically timed ventricular stimulation during electrophysiologic studies or, rarely, in patients with temporary or permanent ventricular pacemakers. The following case illustrates how, when temporary ventricular pacing is instituted to maintain heart rate in a patient with a defective permanent ventricular pacemaker, this potentially fatal arrhythmia may occur as a complication of interaction between the two pacemakers.     

Suppression of Storms of Ventricular Tachycardia by Epicardial Ablation of Isolated Delayed Potential in Noncompaction Cardiomyopathy

A 65‐year‐old recipient of an implantable cardioverter defibrillator suffering from ventricular noncompaction developed storms of ventricular tachycardia (VT). Epicardial voltage mapping revealed the presence of a large low‐voltage area in the left ventricular apical and inferoposterior wall, and isolated delayed potential was recorded over 1.5 cm in the posterior border between low and normal myocardial voltage. Pacemapping at the delayed potential recording site produced two different QRS depending on pacing output strength, and these two QRS morphologies were similar to clinically documented VTs. During one of the VTs, a mid‐diastolic potential was recorded from the site with the delayed potential, and rapid pacing produced concealed entrainment. After epicardial radiofrequency ablation of the isolated delayed potential, VTs were noninducible and the VT storm was suppressed.     

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)     

Thorax Percutaneous Approach for Epicardial Ventricular Ablation in a Patient with Electrical Storm

Subxiphoid puncture is considered the standard approach for epicardial ablation of ventricular arrhythmia, but in some cases this access is impracticable due to the patient's anatomy. We describe the case of a patient with electrical storm and abnormal subdiaphragmatic anatomy that precluded the usual subxiphoid approach. In this patient the pericardial space was gained through a direct thorax puncture at the fifth intercostals space close to the mammary line. The tools and technique utilized in this case were similar to what is usually used for traditional subxiphoid puncture. The thorax percutaneous puncture was successfully carried out without complication.     

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)     

Best Clinical Practice: Emergency Medicine Management of Stable Monomorphic Ventricular Tachycardia

Background

Ventricular tachycardia (VT) and ventricular fibrillation are the causes of approximately 300,000 deaths per year in the United States. VT is classified based on hemodynamic status and appearance. Stable, monomorphic VT treatment is controversial.

Sudden Cerebral Vasoconstriction During Induced Polymorphic Ventricular Tachycardia and Fibrillation: Further Observations of a Paradoxic Response

To determine the effect of induced polymorphic VT/VF on the cerebral circulation, transcranial Doppler (TCD) ultrasonography was used to prospectively assess changes in cerebral blood flow velocity during ICD implantation. Fourteen patients (13 men, 1 woman, mean age 58 ± 20 years, range 34-74 years) who were survivors of an out of hospital cardiac arrest, were evaluated during routine ICD implantation. TCD ultrasonography was used to assess middle cerebral artery systolic velocity (V_s), diastolic velocity (Vd), pulsatility index (PI = V_s– V_d/V_mean) and resistance index (RI = V_s-V_alV_s) before, during, and after DFT testing with alternating current induction of polymorphic VT/VF. In each of the 14 patients studied, concomitant with the abrupt onset of hypotension, TCD sonography demonstrated a 33%± 28% decrease in diastolic velocity, a 42%± 28% increase in systolic velocity, a 190%± 141% increase in FI, and a 44%± 19% increase in RI. These findings reflect an increase in cerebrovascular resistance secondary to arteriolar vasoconstriction distal to the point of insonation of the middle cerebral artery. This response is paradoxic, as the expected response of the cerebral circulation to hypotension is vasodilation, but it is consistent with observations made in other acute hypotensive settings, such as tilt induced neurocardiogenic syncope.     

A Case with Catecholaminergic Polymorphic Ventricular Tachycardia Unmasked after Successful Ablation of Atrial Tachycardias from Pulmonary Veins

Catecholaminergic polymorphic ventricular tachycardia (VT) is characterized by polymorphic VT during exercise, and the association of atrial fibrillation (AF) has been reported. However, the mechanism of AF in this disease and the relationship between VT and AF has been obscured. We described a 13-year-old girl who referred for catheter ablation of exercise-induced paroxysmal AF. Multifocal atrial tachycardia mimicking AF on the surface electrocardiogram originated from multiple pulmonary veins (PVs). While AT became non-inducible after the isolation of four PVs, polymorphic VT was initiated by isoproterenol infusion. Polymorphic VT was suppressed during rapid atrial pacing.     

Idiopathic Right Ventricular Outflow Tract Tachycardia: A Clinical Approach

Right ventricular outflow tract (RVOT) tachycardia is the most common form of idiopathic ventricular tachycardia (VT). Phenotypically, RVOT tachycardia segregates into two predominant forms, one characterized by repetitive monomorphic nonsustainnd VT and the other by paroxysmal exercise induced sustained VT. There is an increasing body of evidence to support the concept that both forms of tachycardia reflect disparate clinical manifestations of an identical cellular mechanism (i.e., cAMP-mediated triggered activity), which is identified clinically by the tachycardia's sensitivity to adenosine. The clinical characteristics, natural history, and approaches to therapy of RVOT tachycardia are delineated herein.     

Ventricular Tachycardia and the Cystic Heart: A Case Report

BackgroundHydatid cysts are caused by Echinococcus granulosus infection, and hydatidosis is recognized as a re-emerging zoonotic disease globally. While the liver is the most commonly affected organ, other organs can also be affected, including the heart. Because of the low sensitivity and specificity of serologic diagnostic tests, ultrasound and echocardiography are increasingly used to make the diagnosis of cardiac hydatid cyst.Case reportWe report the case of a cardiac hydatid cyst, detected by point-of-care ultrasound (POCUS), in a 79-year-old woman who presented with shortness of breath and was in ventricular tachycardia. The diagnosis was further confirmed with a computed tomography scan. Although cases of alveolar and liver hydatid cysts are seen, this is the first case of a cardiac hydatid cyst in Bhutan.Why Should an Emergency Physician Be Aware of This?This case illustrates the importance of POCUS in reaching a diagnosis, particularly in resource-poor areas where other sophisticated diagnostic tools are not easily available. A cardiac hydatid cyst must be in the differential for structural causes of dysrhythmias. This is especially so because treatment of unstable dysrhythmias in the acute setting of an emergency department has to be modified from the usual algorithm in the presence of a cardiac hydatid cyst, due to the potentially fatal risk of cyst rupture and anaphylaxis.     

Dual Epicardial Ventricular Tachycardia: A Tale of Two VTs

A young female with isolated ventricular noncompaction and acute myocarditis presented with incessant dual epicardial ventricular tachycardia consisting of a manifest reentrant circuit and a shorter cycle length concealed circuit. A single radiofrequency terminated both tachycardias. (PACE 2012; 35:e1–e5)     

Elimination of Ventricular Arrhythmia in Catecholaminergic Polymorphic Ventricular Tachycardia by Targeting “Catecholamine‐Sensitive Area”: A Dominant‐Subordinate Relationship between Origin Sites of Bidirectional Ventricular Premature Contractions

We report on a patient diagnosed with catechoaminergic polymorphic ventricular tachycardia (CPVT) who underwent catheter ablation of ventricular premature contractions (VPCs) induced by epinephrine. VPCs were classified roughly into three types. Type 1 and Type 2 VPCs (right bundle branch block [RBBB] configuration and inferior axis) were eliminated by radiofrequency applications at the left aortic sinus of Valsalva and the anterolateral papillary muscle (APM), respectively. Although no spontaneous VPCs were seen after the elimination of Type 1 and 2 VPCs, pacing resulting in capture at the APM induced Type 3 VPC (RBBB configuration and superior axis) reproducibly. The electrophysiological findings observed in our representative case have important implications both for understanding the pathophysiology of CPVT and for considering therapeutic strategies.     

新型酪氨酸激酶抑制剂HHGV678对Bcr-Abl野生型细胞株和伊马替尼耐药细胞株抑制作用的体外研究

本研究比较新型的酪氨酸激酶抑制剂HHGV678与伊马替尼(imatinib,IM)在体外对Bcr-Abl野生型和IM耐药细胞株的抑制作用,探索HHGV678替代IM治疗CML及IM耐药CML患者的可能性。以Bcr-Abl野生型细胞株(K562和32Dp210)及16种IM耐药细胞株(K562R和15种Bcr-Abl点突变细胞株)为研究对象,用MTT法检测HHGV678和IM对上述细胞的生长抑制作用;以DNA梯形条带法和Annexin-V/PI双染色流式细胞术检测细胞凋亡;应用Western blot检测HHGV678对上述细胞BCR-ABL融合蛋白及酪氨酸激酶磷酸化表达的影响。结果表明:HHGV678呈剂量依赖性显著抑制Bcr-Abl野生型细胞株和除T315I点突变细胞株以外的IM耐药细胞株生长。比较IC50发现,HHGV678在低剂量下(0.01-0.3μmol/L)抑制K562和32Dp210细胞生长的作用比IM分别强15.5和28倍;而对除T315I点突变细胞株以外的15种IM耐药细胞株细胞的生长抑制作用比IM强1.4-124.3倍。HHGV678抑制上述细胞酪氨酸激酶磷酸化的能力均强于IM。更重要的是HHGV678在10.0μmol/L剂量下诱导IM强耐药细胞株K562R和T315I点突变细胞株的凋亡率分别达到40.06%和33.32%,显著高于IM的19.77%和10.68%。结论:新型酪氨酸激酶抑制剂HHGV678对Bcr-Abl野生型细胞株和IM耐药细胞株,尤其是对IM强耐药细胞株的生长抑制作用明显强于IM,但HHGV678能否成为治疗CML和IM耐药CML患者新的靶向药物,仍有待进一步的研究。     

Catheter Ablation of Ventricular Tachycardia Occurring Late After Myocardial Infarction: A Point-of-View

A Point-of-View. Venfricular tachycardia can be cuntwUed by radiofrequency or chemical ablation of the site of origin of the arrhythmia. However, these techniques are far from being accepted as routine treatment for this problem. This article describes the theoretical and practical background of catheter ablation of ventricuiar tachycardia occurring late after myocardial infarction.