EGC Diagnosis of Paroxysmal Supraventricular Tachycardias in Patients without Preexcitation

This review is aimed at discussing the diagnostic value of the different electrocardiographic criteria so far described in the differential diagnosis of the major forms of paroxysmal supraventricular tachycardias (PSVTs). The predictive value of different combinations of these independent electrocardiographic (ECG) signs in distinguishing atrioventricular reentrant tachycardias (AVRTs) through a concealed accessory pathway (AP) versus atrioventricular nodal reentrant tachycardias (AVNRTs) are discussed in detail. In addition, the adjunctive diagnostic value of simple, bedside clinical variables and their combinations to the ECG interpretation in differentiating both tachycardia mechanisms is also reviewed. Ann Noninvasive Electrocardiol 2011;16(1):85–95     

Postextrasystolic Repolarization Abnormalities in ST‐U Segment in Patients with Ventricular Arrhythmias

Background: Changes in U‐wave amplitude after premature ventricular contractions (PVC) are known as prognostic markers in the long QT syndrome dependent on bradycardia. The purpose of the study was to find correlation between postextrasystolic ST‐U segment changes and a history of sustained ventricular tachycardia or ventricular fibrillation (VT/VF). Methods: The ST‐U segment configurations were taken from the 24‐hour ambulatory ECG. The comparison of the morphology of these segments was performed between sinus beats preceding PVC's and first postextrasystolic beats. Population: Two groups of patients were evaluated: 1) 32 patients with VT/VF history (VT/VF group), and 2) 36 patients with potentially malignant arrhythmia (structural heart disease with frequent PVCs and/or nonsustained VT‐nsVT) tnon‐VT/VF group). Results: We found T‐wave changes in 8 patients (25%) from the VT/VF group and in 12 patients (33.3%) from the nonVT/VF group (P = NS) and U‐wave changes in 13 patients (40.6%) and 3 patients (8.3%), respectively (P < 0.05). Other ECG indexes related to PVC's were also considered: RR interval, coupling interval (Cl), prematurity index (Pl), and postextrasystolic pause (PP). The analysis of these ECG indices revealed, when compared with patients without T‐U‐wave changes, that the occurrence of U‐wave changes was significantly related to longer RR interval of the sinus rhythm preceding PVC: 1025 ± 211 vs 918 ± 200 ms (P < 0.05). The prematurity index was lowest in patients with U‐wave changes: 0.54 ± 0.12 vs 0.65 ± 0.16 (P < 0.01) while postextrasystolic pauses leading to the postextrasystolic U‐wave changes were significantly longer: 1383 ± 223 vs 1130 ± 247 ms (P < 0.001). Cl did not differentiate patients: 556 ± 108 vs 584 ± 117 ms (P = NS). Conclusions: Postextrasystolic changes in ST‐U segment configuration are dependent on bradycardia, low prematurity index of the PVC, and the lengthening of the postextrasystolic pause. U‐wave changes more frequently appeared in patients with malignant arrhythmias. Follow‐up study is needed to assess if they might be predictive for the occurrence or reoccurrence of arrhythmic episodes. A.N.E. 2002;7(1):17–21     

Effect of Corticosteroid Therapy on Ventricular Arrhythmias in Patients with Cardiac Sarcoidosis

Background: Ventricular arrhythmias are one of the main causes of sudden death in cardiac sarcoidosis (CS). Little is known about the efficacy of corticosteroid therapy for ventricular arrhythmias in CS. Methods: Thirty‐one CS patients presenting premature ventricular contractions (PVCs, ≥300/day) were investigated. Fourteen patients had nonsustained ventricular tachycardia (NSVT). All of patients were treated with corticosteroid, and the initial dosage is 30 mg/day of prednisone, which was tapered over a period of 6 months to a maintenance dosage of 10 mg/day. Twenty‐four hour Holter monitoring, signal averaged electrocardiography (SAECG), echocardiography, gallium‐67 scintigraphy, serum angiotensin converting enzyme (ACE) and plasma B‐type natriuretic peptide (BNP) concentrations were assessed before and after corticosteroid therapy. Results: As a whole, there were no significant differences in the number of PVCs and in the prevalence of NSVT before and after steroid therapy. However, the less advanced LV dysfunction patients (EF ≥ 35%, n = 17) showed significant reduction in the number of PVCs (from 1820 ± 2969 to 742 ± 1425, P = 0.048) and in the prevalence of NSVT (from 41 to 6%, p = 0.039). Late potentials on SAECG were abolished in 3 patients. The less advanced LV dysfunction group showed a significantly higher prevalence of gallium‐67 uptake compared with the advanced LV dysfunction group (EF < 35 %, n = 14). In the advanced LV dysfunction patients, there were no significant differences in these parameters. Conclusions: Corticosteroid therapy may be effective for ventricular arrhythmias in the early stage, but less effective in the late stage. Ann Noninvasive Electrocardiol 2011;16(2):140–147     

Supraventricular Arrhythmias in Children and Young Adults with Implantable Cardioverter Defibrillators

INTRODUCTION: Rapidly conducted supraventricular tachycardias (SVTs) can lead to inappropriate device therapy in implantable cardioverter defibrillator (ICD) patients. We sought to determine the incidence of SVTs and the occurrence of inappropriate ICD therapy due to SVT in a pediatric and young adult population. METHODS AND RESULTS: We undertook a retrospective review of clinical course, Holter monitoring, and ICD interrogations of patients receiving ICD follow-up at our institution between March 1992 and December 1999. Of 81 new ICD implantations, 54 eligible patients (median age 16.5 years, range 1 to 48) were identified. Implantation indications included syncope and/or spontaneous/inducible ventricular arrhythmia with congenital heart disease (30), long QT syndrome (9), structurally normal heart (ventricular tachycardia/ventricular fibrillation [VT/VF]) (7), and cardiomyopathies (7). Sixteen patients (30%) received a dual-chamber ICD. SVT was recognized in 16 patients, with 12 of 16 having inducible or spontaneous atrial tachycardias. Eighteen patients (33%) received > or =1 appropriate shock(s) for VT/VF; 8 patients (15%) received inappropriate therapy for SVT. Therapies were altered after an inappropriate shock by increasing the detection time or rate and/or increasing beta-blocker dosage. No single-chamber ICD was initially programmed with detection enhancements, such as sudden onset, rate stability, or QRS discriminators. Only one dual-chamber defibrillator was programmed with an atrial discrimination algorithm. Appropriate ICD therapy was not withheld due to detection parameters or SVT discrimination programming. CONCLUSION: SVT in children and young adults with ICDs is common. Inappropriate shocks due to SVT can be curtailed even without dual-chamber devices or specific SVT discrimination algorithms.     

Electrocardiographic Diagnosis of Atrial Tachycardia: Classification,P‐Wave Morphology,and Differential Diagnosis with Other Supraventricular Tachycardias

Atrial tachycardia is defined as a regular atrial activation from atrial areas with centrifugal spread, caused by enhanced automaticity, triggered activity or microreentry. New ECG classification differentiates between focal and macroreentrant atrial tachycardia. Macroreentrant atrial tachycardias include typical atrial flutter and other well characterized macroreentrant circuits in right and left atrium. Typical atrial flutter has been described as counterclockwise reentry within right atrial and it presents a characteristic ECG “sawtooth” pattern on the inferior leads. The foci responsible for focal atrial tachycardia do not occur randomly throughout the atria but tend to cluster at characteristic anatomical locations. The surface ECG is a very helpful tool in directing mapping to particular areas of interest. Atrial tachycardia should be differentiated from other supraventricular tachycardias. We propose a diagnostic algorithm in order to help the physician to discriminate among those. Holter analysis could offer further details to differentiate between atrial tachycardia and another supraventricular tachycardia. However, if the diagnosis is uncertain, it is possible to utilize vagal maneuvers or adenosine administration. In conclusion, in spite of well–known limits, a good interpretation of ECG is very important and it could help the physician to manage and to treat correctly patients with atrial tachycardia.     

Exercise‐Induced Ventricular Arrhythmias and Cardiovascular Death

Background: Exercise‐induced ventricular arrhythmias (EIVA) are frequently observed during exercise testing. However, the clinical guidelines do not specify their significance and so we examined this issue in our population. Methods: A retrospective analysis of prospectively collected data was performed on 5754 consecutive male veterans referred for exercise testing at two university‐affiliated Veterans Affairs Medical Centers. Exercise test responses were recorded and cardiovascular mortality was assessed after a mean follow‐up of 6 ± 4 years. EIVA were defined as frequent premature ventricular complexes (PVCs) constituting more than 10% of all ventricular depolarizations during any 30‐second ECG recording, or a run of three or more consecutive PVCs during the exercise test or recovery. Results: EIVA occurred in 426 patients (7.4%). There were 550 (10.6%) cardiovascular deaths during follow‐up. Seventy two (17%) patients with EIVA died of cardiovascular causes, whereas 478 (9.0%) of patients without EIVA died of cardiovascular causes (P < 0.001). Patients with EIVA had a higher prevalence of cardiovascular disease, resting PVCs, resting ST depression, and ischemia during exercise than patients without EIVA. In a Cox hazards model adjusted for age, cardiovascular disease, exercise‐induced ischemia, ECG abnormalities, exercise capacity and risk factors, EIVA was significantly associated with time to cardiovascular death. The combination of both resting PVCs and EIVA was associated with the highest hazard ratio. Conclusions: EIVA are independent predictors of cardiovascular mortality after adjusting for other clinical and exercise test variables; combination with resting PVCs carries the highest risk.     

老年高血压患者心律失常特点及其与左室肥厚的关系

分析原发性高血压病226例（老年组139例，非老年组87例）和80例健康老年人（对照组）24h动态心电图检测的心律失常。结果示总房性和室性心律失常发生率在高血压老年组为97％和77％，非老年高血压组为85％和53％，对照组为89％和59％；其中阵发房速、房颤和Lown's分级≥3的室性心律失常在高血压老年组达47％和40％，非老年组21％和22％，对照组30％和11％（P＜0．05～0．001）。在高血压老年组中62例伴左室肥厚（LVH），其总室住心律失常发生率和town's分级≥3者达92％和57％，均高于无LVH者的65％和27％（P＜0．001）。提示其发生与LVH密切相关。     

Role of Radiofrequency Ablation in the Management of Supraventricular Arrhythmias:

Radiofrequency Ablation of Supraventricular Arrhythmias, Introduction: Several reports iiave demonstrated that radiofrequency catheter ablation provides effective control of a variety of supraventricular tachycardias. However, the efficacy, complications, risk of arrhythmia recurrence, and follou-up survival analysis have not been reported in a large series of consecutive patients with supraventricular arrhythmias with diverse electrophysiologic mechanisms. This report details the results of radiofrequency catheter ahiation in 760 consecutive patients (386 males, 374 females) with a wide variety of supraventricular tachycardias treated at one center. Methods and Results: Arrhythmias were associated with the presence of an accessory pathway i n 363 patients (384 accessory pathways), including four patients with Mahaim fibers and eight patients with the permanent form of junctional reciprocating tachycardia. The mechanism of the clinical arrhythmia was AV nodal reentrant tachycardia in 245 patients, and a primary atrial tachycardia in 20 patients (ectopic atrial tachycardia in 16 patients and sinus nodal reentry in 4 patients). Ablation of the reentrant circuit of atrial flutter within the right atrium was attempted i n 13 patients. AV node ahiation and permanent pacemaker implantation were performed in 119 patients with medically refractory atrial fihrillation or flutter. Radiofrequency catheter ahiation was successful in 346 of 363 patients (95.3%, CI 93.I%–97.5%) with accessory pathways (367 of 384 pathways, 95.6%, CI 93.5%–97.6%) with a complication rate of 1.1% and a recurrence rate of 5.5%. Successful accessory pathway ablation was achieved for 179 of the first 192 pathways treated (93.2%, CI 89.7%–96.6%) and increased to 188 of 192 pathways (97.9%, CI 95.9%–99.9%) over the second half of the series. AV nodal reentry was successfully abolished in 244 of 245 patients (99.6%, CI 98.8%–100%) by selective ablation of the slow pathway in 234 patients and the fast pathway in 10 patients. The complication rate in this group was 2.0% with a recurrence rate of 6.5%. All 20 primary atrial tachycardias were successfully ablated with no complications and a recurrence rate of 15%. The reentrant circuit of atrial flutter was ahlated successfully in 10 of 13 patients (77%) with recurrent atrial flutter in one additional patienl. Complete AV block was achieved in 117 of 119 (98.3%, CI 96.0%–100%) patients with atrial fibrillation or flutter treated hy AV nodal ablation with a complication rate of 0.8% and recurrence of AV conduction in 6%. The median duration of fluoroscopy exposure for the population was 23.4 minutes. The overall primary success rate for the entire population was 97.0% (737 of 760 patients, CI 95.8%–98.2%). Conclusion: Thus, the results of this large series of patients demonstrates the safety and efiicacy of radiofrequency ahiation for the treatment of a wide variety of supraventricular arrhythmias. It also appears that increasing experience with these procedures increases the rate of successful ahlation and decreases the risk of complications.     

Noninvasive Diagnosis in Patients with Undocumented Tachycardias:

INTRODUCTION: Patients with symptoms suggestive of paroxysmal supraventricular tachycardia (PSVT) but no tachycardia documentation often undergo diagnostic electrophysiologic study. In dual AV node physiology with AV node reentrant tachycardia (AVNRT), the anterograde fast pathway is more sensitive than the slow pathway to the effects of adenosine. The purpose of the study was to test the hypothesis that adenosine can be used as a bedside test for the diagnosis of dual AV node physiology and hence for AVNRT. METHODS AND RESULTS: During electrophysiologic study, 37 patients without prior documentation but symptoms indicative for PSVT received incremental dosages of adenosine during sinus rhythm until second-degree or greater AV block was observed. Suggestive signs of dual AV node physiology on the surface ECG (sudden jump of PQ interval > or = 50 msec) were found in 13 (76%) of 17 patients with inducible AVNRT but in only 1 (5%) of the remaining patients (P < 0.01). In the AVNRT group, the maximal increase of the PQ interval between two beats was greater (88+/-45 msec) than in the remaining 20 patients (17+/-11 msec) (P < 0.01). CONCLUSION: Careful evaluation of surface ECG during administration of adenosine helps to identify patients prone to AVNRT. The adenosine test is a valuable noninvasive adjunct in patients with undocumented palpitations suggestive of PSVT.     

缝隙连接阻滞剂预防缺血性室性心律失常及其机制的研究

目的观察缝隙连接阻滞剂类Heptanol对局部心肌缺血性室性心律失常发生率的影响,并探索可能的作用机制。方法①结扎离体SD大鼠冠状动脉前降支,造成左心室前壁局部缺血,观察不同浓度Heptanol对缺血所致室性心律失常发生率的影响。②取缺血部分心肌进行免疫荧光染色及RT PCR检测,应用图像分析系统半定量分析CX43蛋白及mRNA的水平。③实验动物随机分为5组,每组12只,分别为对照组、缺血组、0.1mMHeptanol组、0.3mMHeptanol组、0.5mMHeptanol组。结果①Heptanol可明显降低由于缺血引起的室性心动过速(室速)和心室颤动(室颤,缺血组45%;0.1mMHepta nol组10%;0.3mMHeptanol组0;0.5mMHeptanol组10;P<0.05)。②缺血心肌CX43蛋白表达面积比正常心肌明显减少,Heptanol可使缺血所致的CX43蛋白的减少发生部分逆转(对照组1706±397;缺血组561±147;0.1mMHeptanol组1027±215;0.3mMHeptanol组1112±301;0.5mMHeptanol组1179±425,P<0.05)。mRNA表达与蛋白水平的变化相一致。结论①Heptanol可以减少由于局部缺血引起的室速和室颤发生率。②Heptanol可以部分逆转缺血引起的CX43mRNA和蛋白表达下调。     

冠心病患者Tp-e间期与复杂性室性心律失常关系的研究

目的观察不同方法（Tmax法、T均法和TV3法）测得的冠心病患者Tp—e间期差异以及其与复杂性室性心律失常的关系。方法315例患者的12导联心电图通过计算机图像软件处理获得Tp—e间期资料,同时行动态心电图检查并按检查结果分组：A组,冠心病单纯室性期前收缩频发组（室性期前收缩≥30次／h）;B组,冠心病复杂性室性期前收缩组（多形性、多源性、R在T上、连发室性期前收缩,可合并室性逸搏）;C组,冠心病室性心动过速、心室扑动及颤动组;D组．冠心病对照组（无明显快速性室性心律失常,室性期前收缩〈30次／h,且无其他室性心律失常）;E组．正常对照组。评价上述3种不同方法测得的Tp-e间期对室性心律失常的预测能力并将Tp—e间期与Q—T间期离散度（Q—Td）进行比较。结果B、C组的Tp-e问期不仅显著大于正常对照组,也显著大于冠心病对照组（P〈0．05）。而A组Tp—e间期大于对照组,但差异无统计学意义（P〉0.05）。结论Tp—e间期对复杂性室性心律失常有预测价值。且优于Q-Td。     

A Device and a Method for Simulating Supraventricular Arrhythmias in Pacemakers Implanted in Patients: Assessment of Safety and Reliability

Automatic mode switching, enabling the pacemaker to pace at an independent ventricular rate when atrial fibrillation occurs, was introduced to provide protection against rapid ventricular pacing during atrial arrhythmia. This study proposes a technique to test automatic mode switching performance. It is based on a programmable system (Arrhythmia Simulator) generating pulse trains that, when applied to the patient's skin, may interfere with the implanted device simulating supraventricular arrhythmias. The amplitude of the output signals is 5 V and they are delivered through an output resistance of 50 k limiting the current to 100 A that guarantees no risk of muscle stimulation during the test and meanwhile low noise signals on the surface ECG. The duration of pulses is 20 ms. Pulses delivered by the Arrhythmia Simulator were correctly sensed by the pacemaker's atrial channel, and the detected amplitude was 2 ± 0.8 mV, ranging from 1 to 3 mV. The performance of the system was reliable and safe in every patient despite the use of different pacemaker leads. Automatic mode switching was induced in every patient at every attempt. The pulses delivered by Arrhythmia Simulator didn't alter the quality of ECG tracings making easy and reliable the analysis.     

Fragmented QRS Is Associated with All‐Cause Mortality and Ventricular Arrhythmias in Patient with Idiopathic Dilated Cardiomyopathy

Background: Several studies have showed that fragmented QRS complexes (f ‐ QRS, defined as different RSR′ patterns) on a routine 12 ‐ lead electrocardiogram were associated with increased mortality and arrhythmic events in patients with coronary artery disease, but relatively little data were available regarding idiopathic dilated cardiomyopathy (IDCM). Objective: The purpose of this study was to evaluate the relationship between fragmentation of QRS and the combined end point of all‐cause mortality and ventricular arrhythmias in patients with IDCM. Methods: One hundred twenty‐eight patients with IDCM and left ventricular dysfunction (ejection fraction, EF ≤ 40%) were analyzed, respectively. According to QRS duration and the existence of f ‐ QRS on 12‐lead electrocardiograph (ECG), the study populations were divided into three groups: (1) the f ‐ QRS group (QRS <120 ms and with fragmented QRS, n = 51), (2) the wide QRS (wQRS) group (QRS ≥ 120 ms, n = 48), and (3) the nonfragmented QRS (non‐fQRS) group (QRS < 120 ms and without f ‐ QRS, n = 29). Results: During a mean follow‐up of 14 ± 5 months, 25 (19.5%) patients had deaths and ventricular arrhythmic events. The combined end point of all‐cause mortality and ventricular tachyarrhythmias was significantly higher in the f ‐ QRS and wQRS groups than the non‐fQRS group (23.5%, 25%, and 3.4%, respectively; P < 0.05 for both). Event‐free was significantly decreased in the f ‐ QRS group versus the non‐fQRS group (P = 0.02). Univaritae regression analysis revealed that f ‐ QRS was a stronger predictor of mortality and arrhythmic events in IDCM patients. Conclusion: f ‐ QRS on 12‐lead ECG has a high predictive value for the combined end point of all‐cause mortality and ventricular tachyarrhythmias in IDCM patients with left ventricular dysfunction. Ann Noninvasive Electrocardiol 2011;16(3):270–275     

Propafenone: An Effective Agent for the Management of Supraventricular Arrhythmias

Propafenone in SVT. Propafenone is a sodium channel blocking antiarrhythmic drug. It also has β-adrenergic, potassium channel, and weak calcium channel blocking activity. The drug is metabolized in the liver with rates dependent on the debrisoquin phenotype. The saturable metabolism results in nonlinear pharmacokinetics. The metabolites retain sodium channel blocking activity but little β-adrenergic blocking activity. Both controlled and noncontrolled studies have documented its efficacy in a variety of supraventricluar arrhythmias. Intravenous propafenone is effective in converting atrial fibrillation to normal sinus rhythm. Chronic oral administration decreases the frequency of recurrence of atrial fibrillation and paroxysmal supraventricular tachycardia. The drug is particularly effective in the Wolff-Parkinson-White syndrome. The drug may produce SA block in patients with underlying sinus node dysfunction. Propafenone has comparatively few noncardiac side effects. It is a useful primary drug or an alternative to more commonly used drugs used for the treatment of supraventricular arrhythmias.     

Propafenone—Clinical Electrophysiology and Efficacy in Patients with Documented or Potentially Life-threatening Arrhythmias

Propafenone is a new antiarrhythmic agent that inhibits the fast sodium channel and decreases phase 0 of the cardiac action potential. Since it has relatively little effect on the action potential duration, it has been classified as a type IC agent. Propafenone prolongs electrocardiographic intervals including PR and QRS. In addition, atrial and ventricular refractory periods generally are lengthened. Initial reports suggest a favorable effect on suppressing conduction over accessory pathways. Propafenone has been shown to have effectiveness in suppressing life-threatening ventricular arrhythmias as well. Electrophysiological testing is useful, but data such as mode of induction and rate of induced tachycardia should be considered in addition to inducibility status.     

Hypoglycemic Effect of Cibenzoline in Patients with Abnormal Glucose Tolerance and Frequent Ventricular Arrhythmias

While some antiarrhythmic agents have potential hypoglycemic effects and indeed some reports of hypoglycemic adverse effect of those drugs, no systematic reports have been issued. We studied the hypoglycemic effects of cibenzoline, a class I antiarrhythmic agent. Cibenzoline succinate (150–300 mg/day) was given orally for 12 weeks to 10 patients who had ventricular premature complexes (VPCs) of <1000 per 24 hours and abnormal glucose tolerance before treatment with cibenzoline. Abnormal glucose tolerance, judged by a 75-g oral glucose tolerance test (OGTT), was defined as the response designated as diabetic or borderline type according to the criteria specified by the Japan Diabetes Society. In OGTT, the insulinogenic index (defined as the ratio of the increment of IRI [immunoreactive insulin] to that of plasma glucose at 30 minutes after a glucose load) and the sum of IRI (IRI) were also determined. Holter ECG recordings, OGTT, and measurements of fasting plasma glucose IRI, and HbA_{1 c} were performed before and during cibenzoline treatment. Cibenzoline caused VPC reduction of < 70% in 6 of the 10 patients. The drug significantly decreased fasting plasma glucose and HbA_{1 c} (mean ± SD) 12 weeks after treatment, from 6.18 ± 0.92 mM/L to 5.54 ± 1.08 mM/L and from 6.17 ± 1.03% to 5.83 ± 0.96%, respectively (P < 0.05). While it significantly increased fasting IRI from 4.99 ± 1.50 to 6.51 ± 1.47 U/mL (P < 0.01), the insulinogenic index from 0.33 ± 0.26 to 0.65 ± 0.38 (P < 0.05), and IRI from 168 ± 67 U/mL to 199 ± 46 (P < 0.05). Cibenzoline exerted a hypoglycemic effect, facilitating insulin secretion in patients with abnormal glucose tolerance and ventricular arrhythmias.