室上性心动过速的射频消融治疗

应用射频导管消融术治疗室上性心动过速204例。其中房室折返性心动过速175例;房室结折返性心动过速28例;房性心动过速1例。成功 189例,成功率为92.7％。有5例出现并发症,占2.45％。随访 1～36个月,有8例复发,5例再次消融成功。我们认为射频消融术是一种安全和有效的根治室上性心动过速主要方法。     

Ten-Years Follow-Up of 20 Patients with Idiopathic Ventricular Tachycardia

The follow-up and characteristics of 20 patients with ventricular tachycardia (VT) and no detectable heart disease is reported. These were 16 men and four women with a mean age of 44 years. Symptoms were present in 18 patients (eight had syncope and ten palpitations or dizziness), VT was sustained in 11 patients and a left bundle branch block morphology with inferior axis was found in 17 patients. In three patients, VT had a right bundle branch block morphology and left-axis deviation. The VT was inducible in 13 patients during the electrophysiological testing (EP) and was sustained in five patients. Medical treatment was introduced in 19 patients. During a mean follow-up of 10 years from the onset of the symptoms and 6 years from the EP testing, one patient died suddenly. He had stopped taking amiodarone 5 months before. In seven patients symptoms recurred and were due to discontinuation of therapy in two cases and inefficacy of previous effective treatment in five patients. After modification of the treatment (three cases), implantation of a pacemaker (one case) and catheter ablation (one case), all patients became asymptomatic. Eleven patients became asymptomatic with the first administered antiarrhythmic therapy. One patient continues to be asymptomatic in spite of discontinuation of his medical therapy. We conclude that patients with VT and no detectable heart disease have a good long-term prognosis and that appropriate therapy can be found in almost all patients.     

Mechanisms for the Success and Failure of Pacing for Termination of Ventricular Tachycardia: Clinical and Hypothetical Considerations

The effectiveness of pacing techniques for termination of ventricular tachycardia is well established, and of great value in the elec-trophysiologic laboratory, and, to a more limited degree, for chronic therapy using implanted anti-tachycardia devices. Although it appears that most clinical ventricular tachycardias are due to reentrant mechanisms, responses to antitachycardia pacing have often been difficult to understand. In this paper, clinical observations are correlated with hypothetical constructs and considerations, in an attempt to derive some general principles related to the success and failure of pacing for ventricular tachycardia. In these analyses, it appears that properties of conductivity and refractoriness in the myocardium are as important as the properties of the tachycardia circuit. Programmed extrastimuli or rapid pacing result in shortening of the effective refractory period of the myocardium, together with depressed conduction velocity of the stimulated wavefront. However, the changes in wavefront conductivity do not occur in step with changes in the effective refractory period; as a result, the stimulated wavefront arrives at the tachycardia circuit in a pattern which differs from the stimulation pattern. In general, it appears that termination of the tachycardia is favored when the stimulated wavefront arrives at the tachycardia circuit at a point when it cannot enter the circuit in an antegrade direction. These conditions are favored by a refractory period in the circuit which is moderately long compared to that of the myocardium. Constructions explaining the observation of a tachycardia termination zone are presented, together with explanations for failure to achieve termination, and for various patterns of acceleration.     

Diagnostic Approach to Narrow Complex Tachycardia with VA Block

Narrow complex tachycardia with VA block is rare. The differential diagnosis usually consists of (1) junctional tachycardia (JT) with retrograde block: (2) AV nodal reentrant tachycardia (AVNRT) with proximal common pathway block; and finally (3) nodofascicular tachycardia using the His-Purkinje system for antegrade conduction and a nodofascicular pathway for retrograde conduction. Analysis of tachycardia onset and termination, the effect of bundle branch block on tachycardia cycle length, and the response to atrial and ventricular premature depolarization must be carefully done. Making the correct diagnosis is crucial as the success rate in eliminating the tachycardia will depend on tachycardia mechanism.     

Catheter ablation for ventricular tachycardia: indications and techniques

Ventricular tachycardia (VT) may be secondary to many different underlying pathophysiologies. The nature of the underlying disorder determines amenability to catheter ablation, thus, dictating the circumstances under which it should be undertaken. The differing substrates also influence the choice of techniques that are used. The most intensively studied clinical subgroup of VT is re-entrant VT in the setting of ischemic heart disease. The approach to ablation in such patients is discussed in detail. Subsequent discussion focuses on other clinically encountered varieties of VT and the ablation methods used in each individual disease state.     

Apropos "tachycardia begets tachycardia"

It has been shown that a tachycardia can facilitate the induction of the same ("atrial fibrillation begets atrial fibrillation") or a different tachycardia. This may also apply for pacemaker-mediated tachycardia as the present case documents.     

Broad QRS tachycardia: Electrocardiographic diagnosis and management

The diagnostic difficulties between supraventricular tachyarrhythmias with intraventricular conduction delay and ventricular tachycardia have challenged the physician since the first recording of a ventricular tachycardia by Lewis in 1909. The examples selected emphasize some of the diagnostic and therapeutic dilemmas of "broad QRS tachycardias" and their major differential features from abberrancy. Multiple simultaneous surface ECG leads are valuable in showing the direction of the initial activation forces of the QRS complexes, the frontal QRS axis and the configuration of the QRS in lead V1. Vagal maneuvers and intra-atrial or esophageal leads are very useful in demonstrating the underlying atrial rhythm and atrioventricular dissociation when present. In life-threatening situations, urgent therapy or D.C. cardioversion may be required before a definitive diagnosis has been established. In recent years electrode catheter techniques for the diagnosis, for arrhythmia induction and for the selection and assessment of the effectiveness of the antiarrhythmic drug therapy have been carried out in the management of recurrent broad QRS tachycardia. In view of the inherent risks with the use of this invasive technique, it should be restricted to a carefully selected number of patients with recurrent life-threatening dysrhythmias as suggested by Scheinman.     

Antitachycardia Strategies

The development of an antitachycardia strategy requires a cascade of assessments and decisions. The patient's problem and level of risk must be assessed in order to determine the goals of therapy. Empirical therapy is appropriate in low-risk situations, and during that ultimate emergency, the treatment of cardiac arrest. Quantitative objective assessment of therapeutic efficacy is indicated in most other situations. Such assessments may be primarily passive, such as recording of drug blood levels or serial Holter monitoring; of provocative, as in serial electrophysiologic, exercise, or psychological stress testing. Selection of an antiarrhythmic modality requires a balance between the risk of therapy and the risks related to the arrhythmia. Any antitachycardia strategy must also consider relative costs, and regulatory and reimbursement policies.     

Atrial Tachycardia Mimicking Atrioventricular Nodal Reentry Tachycardia

Background

The term supraventricular tachycardia (SVT) is used to describe tachydysrhythmias that require atrial or atrioventricular nodal tissue for their initiation and maintenance. SVT can be used to describe atrioventricular nodal reentry tachycardia, atrioventricular reentry tachycardia, and atrial tachycardia (AT). AT is the least common of these SVT subtypes, accounting for only 10% of cases. Although the suggested initial management of each SVT subtype is different, they all can present with similar symptoms and electrocardiographic findings.

Objective

Discuss the pathophysiology, diagnosis, and treatment of AT as compared with other types of SVT.

Case Report

We report a 56-year-old woman with symptoms and electrocardiographic findings consistent with SVT. Although standard treatment with intravenous adenosine failed to convert the SVT, it revealed AT as the cause of the tachydysrhythmia. The AT was successfully terminated with beta-blockade and the patient eventually underwent successful radioablation of three separate AT foci.

Conclusions

AT frequently mimics other more common forms of SVT. AT might be recognized only when standard treatment of SVT has failed. Identification of AT in this setting is crucial to allow for more definitive therapy.     

房室结折返性和房室折返性心动过速的对比研究

【目的】探讨房室结折返和房室折返性心动过速（AVNRT,AVRT）的特点及射频消融（RFCA）的疗效和安全性。【方法】回顾性分析本院近6年行RFCA的823例AVNRT和AVRT患者的临床和电生理特点及手术情况。【结果】AVRT较AVNRT多见．AVNRT女性多于男性,而AVRT男性多见（P〈0．01）。AVRT中左侧较右侧旁路多见。左侧旁路以隐匿性为主．而右侧旁路以显性为主（P〈0．01）;左侧旁路男性多见,而右侧旁路以女性为主（P〈0．01）。右侧显性旁路手术成功率明显低于其他旁路和AVNRT（P〈0．05和P〈0．01）．术后复发率明显高于左侧旁路（P〈0．05和P〈0．01）。2例AVNRT术后出现房室传导阻滞而植入心脏起搏器,发生气胸和血气胸6例。心包填塞1例．假性动脉瘤3例,1例左侧旁路放电时出现心室纤颤。无一例患者死亡。【结论】AVNRT和AVRT消融手术成功率高而复发率低．严重并发症较少．RFCA治疗AVNRT和AVRT是有效和安全的。     

Wide‐QRS‐Complex Tachycardia with a Negative Concordance Pattern in the Precordial Leads: Are the ECG Criteria Always Reliable?

We present a case of wide-complex tachycardia with negative concordance in the precordial leads and a qR pattern in V6, in a 42-year-old man with risk factors for coronary artery disease, in whom the electrocardiogram criteria were apparently fallible. This case highlights the key contribution of the electrophysiological study in rendering correct diagnosis.     

Longitudinal Dissociation within the Reentry Pathway of Ventricular Tachycardia

SATULLO, G., ET AL.: Longitudinal Dissociation within the Reentry Pathway of Ventricular Tachycardia. Two cases of nonsustained, repetitive ventricular tachycardia are analyzed. In both, the episodes of tachycardia do not contain random numbers of beats, but the complexes in each phase of tachycardia are either always in even numbers (case 1) or always in odd numbers (case 2). This indicates longitudinal dissociation within the reentry circuit: i.e., there are two functionally separate pathways in some part of the reentry circuit, and the reciprocating impulse runs alternatively through the two pathways. Tachycardia ends due to block of the impulse always in the same pathway, thus, the number of beats in each episode of tachycardia is always either in odd or even numbers. (PACE, Vol. 13, December, Part 1 1990)     

Infraatrial supraventricular tachycardias: mechanisms, diagnosis, and management

Tachycardias are traditionally classified as either ventricular tachycardia (VT) or supraventricular tachycardia (SVT). VT can be defined as a tachycardia which requires only ventricular structures for perpetuation. SVT is defined in terms of exclusion of VT and hence is any tachycardia which requires participation of at least one supraventricular structure for perpetuation. Certain SVTs require only participation of the atrioventricular node (AVN) and the His bundle (HB) but not the atrial myocardium or any of the great thoracic veins for perpetuation and hence can be described as "infraatrial." The three main mechanisms of infraatrial SVTs are: (1) intranodal atrioventricular reentrant tachycardia; (2) junctional ectopic tachycardia; and (3) nodoventricular reentrant tachycardia. The clinical significance of infraatrial SVTs is that they are compatible with any A:V ratio and even atrioventricular (AV) dissociation. Infraatrial SVTs are often suspected when a narrow complex tachycardia presents with apparent AV dissociation and a counterintuitive A:V ratio of < 1:1. However, if the same tachycardia is conducted with aberrant conduction or preexcitation, a broad complex tachycardia with an A:V ratio of < 1:1 will arise and that can be easily mistaken for VT. The possible patterns of electrical association and dissociation between different cardiac structures are examined, and how individual types of infraatrial SVT can be diagnosed and managed are reviewed.     

Is Sinus Node Modification Appropriate for Inappropriate Sinus Tachycardia with Features of Postural Orthostatic Tachycardia Syndrome?

Inappropriate sinus tachycardia and postural orthostatic tachycardia are ill-defined syndromes with overlapping features. Although sinus node modification has been reported to effectively slow the sinus rate, long-term clinical response has not been adequately assessed. Furthermore, whether patients with postural orthostatic tachycardia would benefit from sinus node modification is unknown. The study prospectively assessed the short- and long-term clinical outcomes of seven consecutive female patients with postural orthostatic tachycardia syndrome and inappropriate sinus tachycardia who were treated with sinus node modification. The study was conducted in a tertiary care center. The electrophysiological and clinical responses were prospectively assessed as defined by autonomic function testing, including Valsalva maneuver, deep breathing, tilt table testing, and quantitative sudomotor axonal reflex testing. Among the study population (mean age was 41+/-6 years), 5 (71%) patients had successful sinus node modification. At baseline, heart rates were 101+/-12 beats/min before modification and 77+/-9 beats/min after modification (P = 0.001). With isoproterenol, heart rates were 136+/-9 and 105+/-12 beats/min (P = 0.002) before and after modification, respectively. The mean heart rate during 24-hour Holter monitoring was also significantly reduced: 96+/-9 and 72+/-6 beats/min (P = 0.005) before and after modification, respectively. Despite the significant reduction in heart rate, autonomic symptom score index (based on ten categories of clinical symptoms) was unchanged before (15.6+/-4.1) and after (14.6+/-3.6) sinus node modification (P = 0.38). Sinus rate can be effectively slowed by sinus node modification. Clinical symptoms are not significantly improved after sinus node modification in patients with inappropriate sinus tachycardia and postural orthostatic tachycardia. A primary subtle autonomic disregulation is frequently present in this population. Sinus node modification is not recommended in this patient population.     

Management of Pacemaker Circus Movement Tachycardias

DDD pacemakers were implanted in 11 patients of whom 5 had the capacity to conduct retrogradely to the atrium. Methods to prevent or terminate pacemaker circus movement tachycardia (PCMT) were evaluated in these patients. V-A conduction was assessed before implantation by incremental right ventricular pacing while recording right atrial electrograms. Following implantation and at quarterly outpatient clinic visits, V-A conduction and ability to initiate and sustain PCMT were systematically assessed by non-invasive techniques. PCMT could be induced non-invasively in all 5 patients. The methods used to reduce and terminate the incidence of PCMT were: 1) decreasing the atrial sensitivity; 2) stressing the V-A conduction system by programming a high upper rate with an appropriately short A-V interval; 3) programming a low lower rate; 4) avoiding the Wenckebacb response (by programming a high upper rate); 5) medication; and 6) occasionally by using a magnet. PCMT was controlled in all patients, in 2 patients by programming measures only and in 2 with the addition of medication. One patient who refused medication had to be programmed into another pacing mode. We conclude that : 1) the presence of V-A conduction is not an absolute contraindication to the use of a DDD pacing system; 2) pacing the ventricle early enough to cause V-A block was the most useful method to terminate PCMT; 3) future generation DDD pacemakers should prevent initiation of PCMTs while maintaining the possibility to synchronize to exercise-induced high atrial rates.