Combined epicardial-endocardial approach to ablation of inappropriate sinus tachycardia

A combined epicardial-endocardial approach to ablation of inappropriate sinus tachycardia in a highly symptomatic patient who failed to respond to medical therapy and endocardial ablation is described. The anatomy and physiology of the sinus node is discussed, providing a basis for performing this procedure. This case provides an additional therapeutic option for a condition that often is difficult to manage.     

Echocardiographic lesion characteristics associated with successful ablation of inappropriate sinus tachycardia

INTRODUCTION: Catheter ablation of inappropriate sinus tachycardia has proven difficult. Despite the use of intracardiac echocardiography to help direct radiofrequency (RF) application to the anatomic target of the superolateral crista terminalis (CT), multiple RF lesions often are required. Furthermore, the characteristic echo-anatomic changes with RF application associated with a reduction in heart rate have not been defined. A characteristic echo signature, if present, may facilitate the ablation process. The purpose of this retrospective study was to define the echocardiographic characteristic changes associated with effective RF ablation for inappropriate sinus tachycardia. METHODS AND RESULTS: Detailed intracardiac echocardiographic imaging characterization of the superolateral CT was performed before and at the time of successful heart rate reduction. Using on-line videotape intracardiac echocardiography (9 MHz, 9 French), changes in wall thickness and echodensity at the CT lesion site were assessed at baseline, after each RF lesion, and with the lesion that produced heart rate reduction in 17 patients (age 32 +/- 9 years; 15 women) with inappropriate sinus tachycardia. In all patients, RF ablation was anatomically based and targeted only the superolateral CT. RF lesions were created using 20 to 50 W for up to 2 minutes using an 8-mm tip electrode. Successful heart rate reduction (> or = 20 beats/min) was achieved in 15 of 17 patients and required 41 +/- 31 RF applications (range 5 to 110, median 40). Effective RF (reduced heart rate) was observed starting with the 34th +/- 24th lesion (range 3rd to 86th, median 25th). After effective RF, CT wall thickness was increased (11.4 +/- 3.1 mm vs 7.7 +/- 2.4 mm at baseline) and wall swelling expanded to adjacent superior vena cava, but the degree of thickening was not specific for effective RF associated with heart rate reduction. Importantly, we noted echodensity changes reaching directly to the epicardium with the development of a linear low echodensity or echo-free space at the time of effective RF resulting in heart rate reduction. In two patients without effective heart rate reduction, echodensity changes never reached the epicardium. No complications (superior vena cava-right atrial junction orifice narrowing >50% or pericardial effusion) of RF were identified. CONCLUSION: An echocardiographically guided anatomic approach to RF ablation of inappropriate sinus tachycardia is safe and effective. A characteristic echocardiographic signature suggesting transmural/epicardium damage appears to be present at the time of successful heart rate reduction and may serve as an appropriate guide for directing additional RF when using this anatomic echocardiographically based approach.     

Evidence of sinoatrial block as a curative mechanism in radiofrequency current ablation of inappropriate sinus tachycardia

Inappropriate sinus tachycardia is a nonparoxysmal tachycardia characterized by high resting heart rates and a disproportionate response to activity. Sinus node modification with radiofrequency current has been used successfully as treatment for this arrhythmia. However, the electrophysiologic mechanisms leading to successful modification are not yet fully elucidated. We report a case of a patient with drug-resistant inappropriate sinus tachycardia in whom successful treatment of the arrhythmia was achieved by documented sinoatrial exit block induced by radiofrequency current applications.     

Permanent left atrial tachycardia: radiofrequency catheter ablation through the coronary sinus

The case of a 13-year-old child with an unusually localized "focal" permanent atrial tachycardia is reported. Electrophysiologic study showed that the earliest atrial activation occurred in the distal coronary sinus and preceded the atrial depolarization recorded along the endocardial side of the lateral part of the mitral annulus. Distal coronary sinus mapping revealed a fragmented, polyphasic atrial electrogram. Radiofrequency current delivery to the site permanently stopped the tachycardia.     

Modification and ablation for inappropriate sinus tachycardia: current status

Inappropriate sinus tachycardia is an ill-defined clinical syndrome with diverse clinical manifestations. Clinical symptoms can range from intermittent palpitations to multisystem complaints. Although there is a general consensus that when the heartbeat exceeds 100 beats per minute at rest or with minimal physiologic challenge, it is considered inappropriate, this quantitative differentiation is quite arbitrary, while validation of the reproducibility of the heart rate/activity correlation can be challenging. Once the clinical diagnosis of inappropriate sinus tachycardia is expected, other supraventricular tachyarrhythmias and medical conditions causing sinus tachycardia should be excluded.The underlying mechanism of inappropriate sinus tachycardia is not well understood. Intracardiac mechanisms such as enhanced intrinsic automaticity, enhanced sympathetic tone, increased sympathetic receptor sensitivity, and blunted parasympathetic tone have been proposed. Evidences for extracardiac mechanisms such as length-dependent autonomic neuropathy, excessive venous pooling, beta-receptor hypersensitivity, alpha-receptor hyposensitivity, altered sympathovagal balance, and brainstem dysregulation have also been reported. Currently, our ability to differentiate primary (intracardiac) from secondary (extracardiac) mechanisms of inappropriate sinus tachycardia is limited.It has been reported that ablative therapy of sinus node is effective in treating patients with symptomatic inappropriate sinus tachycardia. Acute success of sinus node modification/ablation can be accomplished in 70%–100% of the various study populations. Although long-term successful outcome may be accomplished in a few patients, symptoms of palpitations and autonomic characteristics frequently persist. Identification and differentiation of patients who are suitable for ablative therapy versus medical therapy should be one of the central clinical research issues in this patient population.This brief review first considers the clinical and electrophysiologic diagnosis of inappropriate tachycardia and then summarizes the mechanisms of inappropriate sinus tachycardia and related syndromes such as postural orthostatic tachycardia syndrome. Techniques of mapping and ablation of sinus node are discussed briefly. A critical review of the acute and long-term clinical outcomes following sinus node ablation and modification is updated. In conclusion, the precise role of sinus node modification in patients with inappropriate sinus tachycardia remains to be determined. Sinus node modification could be considered in patients with inappropriate sinus tachycardia with persistently increased heart rate in the absence of any autonomic abnormalities. Autonomic laboratory testing should be performed to exclude any evidence of autonomic dysregulation. Clinical research on the pathophysiology of inappropriate sinus tachycardia should be pursued vigorously.     

Electroanatomical mapping and radiofrequency ablation of an accessory pathway associated with a large aneurysm of the coronary sinus.

We report a case of a patient with a left posteroseptal accessory pathway associated with a coronary sinus (CS) aneurysm. The patient had undergone two previous failed ablation attempts at other institutions despite multiple radiofrequency applications delivered within and outside the CS aneurysm. Electroanatomical mapping was performed and allowed delineation of the three-dimensional anatomy of the aneurysm, so as to identify the ventricular insertion site, and to permit successful ablation of the pathway without any complications.     

Successful catheter ablation of an anteroseptal accessory pathway from the noncoronary sinus of Valsalva

We describe a patient who underwent radiofrequency catheter ablation of concealed left lateral and anteroseptal accessory pathways. After successful elimination of the concealed left anterolateral accessory pathway, the earliest retrograde atrial activation was located in the His-bundle region. Complete elimination of the accessory pathway conduction was achieved with a radiofrequency energy application from the noncoronary sinus of Valsalva.     

右侧房室旁道导管射频消融治疗的体会

采用导管射频消融术（ＲＦＣＡ）阻断右侧房室旁道治疗房室折返性心动过速５０例，其中单旁道４５例，双旁道４例，三旁道１例，共５６条旁道。首次消融成功率９４％，二次消融成功率１００％。平均随访９个月，３例复发（６％），均经再次消融成功，其余病例未服用任何抗心律失常药物无心动过速复发，术后除１例右后间隔旁道消融后出现一过性Ⅲ°房室传导阻滞外无其它并发症发生。就右侧旁道消融的体会进行了讨论。     

Halo导管在射频消融右侧房室旁路中的应用

目的　总结 8例射频消融失败或复发的右侧游离壁房室旁路病例 ,应用 Halo导管再次消融成功的经验。　方法　 8例患者 ,2例为复发病例 ,6例为失败病例。电生理检查时根据 Halo导管电极 (环绕在三尖瓣环的心房侧 )在窦性心律和心室 S1 S1 刺激时记录的心内电图初步判定旁路位置 ,然后用大头电极标测消融。　结果　共 9条旁路 (双旁路 1例 ,单旁路 7例 )全部消融成功。Halo导管电极记录最早 V波者 2例 ,最早 A波者 6例 ,大头电极在 H alo导管电极提示最早 A波的电极对的部位均可记录到与之提前度相同或更为提前的成功靶点图。手术时间及 X线曝光时间与对照组比较差异不显著。　结论　在右侧旁路的复发和失败病例的消融过程中 ,放置 H alo导管 ,能够提高成功率 ,减少复发 ,节省标测时间。     

Frequent additional tachyarrhythmias in patients with inappropriate sinus tachycardia undergoing sinus node modification: an important cause of symptom recurrence

Additional Tachyarrhythmias in IST. Background: Symptom recurrence following sinus node modification (SNM) for inappropriate sinus tachycardia (IST) remains significant despite achieving acute procedural success. The impact of non‐IST tachyarrhythmias on symptom recurrence remains poorly characterized. Objectives: The objective was to determine the prevalence and nature of additional tachyarrhythmias preceding and following SNM for IST. Methods: Consecutive patients with IST undergoing SNM at the University of Pennsylvania were studied. SNM was initially performed using an anatomic approach targeting the superolateral crista terminalis under intracardiac echocardiographic guidance and later using an electrophysiologic approach, targeting the site of the earliest right atrial activation during maximum heart rate (HR) with isoproterenol infusion. An effort was made to shift the site more caudally until a decrease of >25% in resting HR was achieved, with a blunted response to isoproterenol and flattening of the P‐wave axis in leads III and aVF. Patients were followed for arrhythmia recurrence. Tachyarrhythmias were documented with electrocardiographic monitoring and then characterized during EP study. Results: Thirty‐three patients underwent SNM and were followed for a mean of 2.0 ± 1.5 years. During follow‐up, 27% developed a non‐IST tachyarrhythmia and 18% developed recurrent IST. Additionally, 42% of patients had a non‐IST tachyarrhythmia prior to SNM. Conclusions: Non‐IST tachyarrhythmias are common in patients with IST before and after SNM. A major reason for symptom recurrence following SNM is development of a non‐IST tachyarrhythmia. These tachyarrhythmias should be detected and treated to optimize patient outcomes. (J Cardiovasc Electrophysiol, Vol. 23, pp. 835‐839, August 2012)     

Left anterior descending coronary artery occlusion after left lateral free wall accessory pathway ablation: what is the possible mechanism?

We describe a complication after radiofrequency (RF) ablation of a left free wall accessory pathway that resulted in acute occlusion of proximal left anterior descending (LAD) coronary artery in a 32-year-old male non-cocaine abuser. An interesting feature is the site of coronary artery occlusion which is remote from the RF application site. The RF energy applications were performed in the left lateral annulus remote from the LAD. The occlusion was successfully treated with placement of an intracoronary stent.     

Patterns of radiofrequency catheter ablation of left free-wall accessory pathways: Implications for accessory pathway anatomy

Despite the abundance of literature on the electrophysiology of accessory pathways, clinical data on their anatomic properties remain infrequent. The small and discrete nature of lesions generated by radiofrequency (RF) energy may allow better characterization of accessory pathway anatomy in the intact heart. RF catheter ablation was performed on 40 left free-wall accessory pathways in 39 consecutive patients with a unipolar endocardial approach. The patterns of accessory pathway ablation were identified. Spatial-electrophysiologic information provided by the ablation catheter at individual sites of RF application and corresponding data from the coronary sinus catheter were correlated with the effects of RF energy on accessory pathway conduction. Of 39 accessory pathways permanently (n = 37) or transiently (n = 2) ablated, 24 had “simple” ablation, with abolition of conduction by one individual RF application. In 15 of 24 pathways that could be crossed by the coronary sinus catheter, the concordance in anatomic and electrophysiologic information between the site of earliest retrograde atrial activation and the effective ablation position (ventricular approach) suggested a perpendicular fiber course. Fifteen pathways had “complex” ablations; of these, eight had spatial-electrophysiologic discordance between the atrial and ventricular insertions, suggesting an oblique fiber orientation. Seven pathways had modification or transient suppression of conduction, with or without subsequent abolition of conduction at identical or physically disparate (1 cm apart) sites; four pathways had sequential ablation of antegrade and retrograde conduction. These raised possibilities of broad fiber span and functional longitudinal dissociation of accessory pathway conduction. Accessory pathways with simple and complex ablations did not differ in clinical and electrophysiologic parameters. Complex ablations demanded more lengthy and difficult procedures. In conclusion, 38% of left free-wall accessory pathways in this series had complex patterns of RF ablation. The results of this study raised interesting implications in regard to accessory pathway anatomy and provided information that might facilitate electrophysiologic guidance of RF accessory pathway ablation.     

左侧房室慢旁路的电生理特征和射频消融靶点的定位

目的 :探讨左侧游离壁慢传导旁路的电生理特点和射频消融方法。方法 :5例患者诱发心动过速后用心室感知S2程序刺激中止心动过速确立心室为房室折返环的一部分。结果 :4例中止心动过速时无心房逆行 A波 ,1例有逆行 A波 ,旁路 1例有递减传导特点 ,均在心室侧消融成功。成功消融靶点 A波较冠状窦标测导管最早 A波提前 8～2 2 m s。结论 :心室感知 S2心室程序刺激终止心动过速是鉴别房性心动过速的可靠方法。     

Right diaphragmatic paralysis following endocardial cryothermal ablation of inappropriate sinus tachycardia.

Inappropriate sinus tachycardia (IST) is a rare disorder amenable to catheter ablation when refractory to medical therapy. Radiofrequency (RF) catheter modification/ablation of the sinus node (SN) is the usual approach, although it can be complicated by right phrenic nerve paralysis. We describe a patient with IST, who had symptomatic recurrences despite previous acutely successful RF SN modifications, including the use of electroanatomical mapping/navigation system. We decided to try transvenous cryothermal modification of the SN. We used 2 min applications at -85 degrees C at sites of the earliest atrial activation guided by activation mapping during isoprenaline infusion. Every application was preceded by high output stimulation to reveal phrenic nerve proximity. During the last application, heart rate slowly and persistently fell below 85 bpm despite isoprenaline infusion, but right diaphragmatic paralysis developed. At 6 months follow-up, the patient was asymptomatic and the diaphragmatic paralysis had partially resolved. This is the first report, we believe, of successful SN modification for IST by endocardial cryoablation, although this case also demonstrates the considerable risk of right phrenic nerve paralysis even with this ablation energy.     

房室多旁道的电生理特征及其射频消融治疗

目的 探讨房室多旁道的电生理特点及射频消融方法。方法 23例患者经电生理检查确定房室多旁道，应用心房和心室刺激诱发室上速，确定每条旁道的电生理特征及与心动过速的关系，按照标测部位对相关旁道逐步消融，以射频消融成功确定旁道位置。结果 23例中检出旁道49条，其中三条旁道3例；左侧多旁道12例，右侧多旁道2例，双侧多旁道9例；左侧多旁道以隐匿性为主；右侧多旁道多为显性；未见心动过速时右侧旁道前传而同侧旁道逆传现象。结论 多旁道患者应首先确定和消融与心动过速相关旁道；左侧多旁道应以诱发心动过速或快速心室起搏方法标测；右侧多旁道应同步描记12导联体表心电图，旁道消融成功可能仅见于QRS波的变化，双侧多旁道应首先消融左侧旁道。     

Successful elimination of concealed accessory pathway-mediated tachycardia by ablation of AV nodal slow pathway

We report a case of atrioventricular reentrant tachycardia (AVRT) using a concealed para-Hisian accessory pathway for retrograde conduction, which also required anterograde conduction over the AV nodal slow pathway to maintain the tachycardia. The shortest VA interval during AVRT (70 ms) was noted at a site with His bundle electrogram amplitude of 0.25 mV. The AVRT was cured by radiofrequency ablation of the AV nodal slow pathway without affecting accessory pathway conduction. The patient has not reported any sustained palpitations at 2 years after ablation while receiving no medications. The case presented in this report illustrates a para-Hisian AVRT that was successfully eliminated by an unconventional approach of ablation of the atrial inputs to the AV nodal slow pathway.     

Closed-chest ablation of left lateral atrioventricular accessory pathways

Thirty patients with a left lateral accessory pathway and drugrefractory tachycardia underwent attempted transcatheter ablationof the accessory pathway. Three had a concealed accessory pathwayand 27 had the Wolff-Parkinson-White syndrome. A quadripolarelectrode catheter was positioned within the coronary sinusin order to locate the earliest retrograde atrial activationduring orthodromic reciprocating tachycardia. The appropriatebipole was used as the radiographic and electrophysiologic referenceof the insertion of the accessory pathway. A catheter was thenintroduced into the left atrium, through a patent foramen ovale(six patients) or after transseptal catheterization (14 patients)according to Croft's technique, or using a retrograde transaorticapproach (10 patients). The mitral annulus was mapped with the left atrial catheterin order to record a synchronous or earlier atrial deflectionthan reference during reciprocating tachycardia. VA' time atthe preablation site was 82 ± 12 ms. Two to seven 160J cathodal shocks (650 ± 205 J cumulative per patient)were delivered at this site in 38 sessions. No significant side-effectsoccurred except for one case of right coronary artery spasmleading to inferior wall infarction. Following fulguration, accessory pathway conduction was abolishedin all patients but one with a second accessory pathway. Duringfollow-up of 1–34 months, all patients but one were freeof tachycardia: reciprocating tachycardia recurred in one patient,who had a concealed accessory pathway, on the third day. Accessorypathway conduction, assessed in 10 other patients 3–26months after the procedure, was absent. Coronary arteriographyperformed in seven patients was normal. Catheter ablation of left free-wall accessory pathways is bothsafe and effective with shocks directly delivered to the mitralannulus through a transseptal or transaortic catheter. It isan attractive alternative to surgical ablation of these accessorypathways.     

隐匿性慢旁束心动过速的诊断和消融

２例隐匿性慢旁束折返性心动过速的诊断依据：１、心房和心室电刺激易诱发和终止心动过速；２、心动过速时体表心电图呈窄ＱＲＳ波，递行Ｐ波及ＰＲ〈ＰＲ；３、心动过速与右心室起搏均呈同样的偏心性心房激动顺序；４、心动过速时于希司速不应期刺激心室可提前夺获心房；５、经旁速室房传导呈递减性，未发现旁束有前传能力；６、射频消融心动过速的逆传支后表现为室房分离。射频消融需在心运过速或心起搏时仔细标测三尖瓣环，寻找最