A new protocol of programmed stimulation for assessment of predisposition to spontaneous ventricular arrhythmias

We have devised a simple method for identifying predispositionto spontaneous sustained ventricular fibrillation (VF) and tachycardia(VT). A standardized protocol of programmed stimulation wasapplied to 111 control subjects without ventricular diseaseand with no history of VF or VT (Group I) and to 27 patientswith previous myocardial infarction and documented spontaneous(in the absence of evidence of further acute myocardial ischaemia)VF or VT (Group II). The stimulation protocol consisted of singleand paired ventricular extrastimuli introduced during ventriculardrive at the right ventricular apex and ouflow tract, at twicediastolic threshold current intensity and at 20 mA. None ofthe Group I subjects exhibited VF or sustained (more than 10s) VT. In contrast sustained arrhythmias were induced in 24(89%) of Group II patients. We conclude: In our study population,initiation of a sustained ventricular tachyarrhythmia at programmedstimulation was both a sensitive (89%) and specific (100%) indicatorfor predisposition to spontaneous VF and VT.     

Holter monitoring versus programmed ventricular stimulation

Both Holter monitoring and programmed ventricular stimulation are useful techniques for guiding antiarrhythmic therapy. However, they are not both appropriate for all patients. Holter monitoring is only useful in patients who have consistent and frequent ventricular ectopic beats, and programmed ventricular stimulation requires that the patients have an arrhythmia that is reproducible and inducible. Patients for whom these techniques are used to identify agents that are effective for control of their arrhythmias generally have a better prognosis than those patients for whom an effective agent is not found. Programmed ventricular stimulation may have a better predictive value than Holter monitoring, but the comparison may not be valid, because the procedures are used in different types of patients     

Comparison of the results of programmed ventricular stimulation from the right ventricular apex and outflow tract: a randomized, prospective study

Objective: The aim of this prospective study was to analysethe yield of programmed ventricular stimulation at the rightventricular apex compared with the outflow tract. Methods: A stepwise randomized cross-over protocol of programmedventricular stimulation with alternating stimulation at bothsites was used in 66 patients who were studied because of sustainedventricular tachycardia (n = 30), ventricular fibrillation (n= 7), or non-sustained ventricular tachycardia and/or syncope(n = 29). Results: There were no significant differences between the resultsof stimulation from either right ventricular site with regardto the presence or absence of structural heart disease, spontaneousarrhythmia, ejection fraction or effective refractory periods.Overall, monomorphic ventricular tachycardia was inducible in33 patients (50%); in 25 patients (75.8%), this arrhythmia wasinduced from both sites. However, in only 17 of these 25 patients(68%) did the induced monomorphic ventricular tachycardias havethe same morphologies and similar (± 50 ms) cycle lengths.Ventricular fibrillation was inducible in 11 patients (17%),mostly by three extrastimuli (n=8; 73%). Conclusions: (1) stimulation from at least two right ventricularsites is desirable because of their independent contributionto the induction of ventricular tachyarrythmias, (2) the non-inducibilityor inducibility at one ventricular site does not predict theeffect at another stimulation site, (3) the effective refractoryperiod at the right ventricular apex and outflow tract do notdiffer, (4) the inducibility of multiple ventricular tachycardiamorphologies emphasizes the importance of documenting the causeof spontaneous arrhythmias with multiple electrocardiographicleads to ensure the correct interpretation of arrhythmias inducedby programmed stimulation, (5) clinical or haemodynamic featurescannot predict whether one or more stimulation sites will berequired for induction of ventricular tachycardia. These resultsare important for the diagnostic evaluation and assessment ofpharmacological or non-pharmacological interventions.     

Comparison of endocardial and epicardial programmed stimulation for the induction of ventricular tachycardia

Twenty-seven patients who had pairs of stainless steel wire electrodes placed on the right and the left ventricle during cardiac surgery underwent both epicardial and endocardial programmed ventricular stimulation to assess the inducibility of ventricular tachycardia. Twenty-six of the patients had coronary artery disease and were studied to evaluate map-guided surgery for treatment of ventricular arrhythmias. Burst ventricular pacing and up to three ventricular extrastimuli coupled to two drive train cycle lengths were delivered from the right and left ventricular epicardial wire electrodes and from endocardial catheter electrodes placed at the apex and outflow tract of the right ventricle. Ventricular tachycardia was reproducibly induced in three patients by both endocardial and epicardial stimulation. In one patient ventricular tachycardia was reproducibly induced by epicardial stimulation, but nonreproducible, nonsustained ventricular tachycardia was induced by endocardial stimulation. Ventricular tachycardia remained inducible by both endocardial and epicardial stimulation in three instances (two patients) during drug therapy. A negative study (less than 10 consecutive ventricular beats induced) was obtained in 23 patients by both endocardial and epicardial stimulation. The patients were followed up for 12 to 43 months (average 31). Sudden death or documented ventricular tachycardia occurred in two of the three patients with a positive study by both endocardial and epicardial stimulation. Nineteen (83%) of the 23 patients with concordantly negative studies remained free of arrhythmias. On the basis of concordant results of endocardial and epicardial stimulation (p = 0.001) these results suggest that epicardial stimulation of the right and the left ventricle is an acceptable method to assess the postoperative inducibility of ventricular tachycardia.(ABSTRACT TRUNCATED AT 250 WORDS)     

Role of programmed ventricular stimulation in patients with Brugada syndrome: a meta-analysis of worldwide published data.

AIMS: Brugada syndrome (BS) is an ion channelopathy with the risk of sudden cardiac death. The role of programmed ventricular stimulation (PVS) in risk stratification has been controversially discussed. Therefore, we performed a meta-analysis on the prognostic role of PVS in BS. METHODS AND RESULTS: A Medline search until July 2006 documented 822 entries for BS. Only English publications with > 10 patients and a follow-up period were considered (n = 15). Patients [n = 1217; 974 males (80%)] were divided into three groups: survived sudden cardiac arrest (SCA) [n = 222 (18%)], syncope (Syncope) [n = 275 (23%)], and asymptomatic patients (Asympt) [n = 720 (59%)]. PVS was conducted in 1036 patients (85%). In 548 patients (53%), sustained ventricular tachyarrhythmias (VT) or ventricular fibrillation (VF) was inducible. During follow-up (34 +/- 40 months), VT/VF occurred in 141 patients. SCA bore the highest chance for a VT/VF occurrence during follow-up [odds ratio (OR) 14.4 compared with asymptomatic patients; P < 0.0005]. However, except for one study, the OR for VT/VF during follow-up in relation to VT/VF inducibility was non-significant (OR 1.5; P = ns). CONCLUSION: The main finding is that we were unable to identify a significant role of PVS with regard to arrhythmic events during follow-up in BS, thus questioning the role of PVS for risk stratification in patients with BS. Patients with BS and survived SCA show the highest chance for VT/VF occurrence during follow-up.     

Usefulness of epicardial impedance evaluation for epicardial mapping and determination of epicardial ablation site for ventricular tachycardia: A pilot study

1 Background

During epicardial mapping, determination of appropriate ablation sites in low voltage areas (LVA) is challenging because of large epicardial areas covered by adipose tissue.

2 Objective

To evaluate the impedance difference between epicardial fat and the epicardial LVA using multiple detector computed tomography (MDCT).

3 Methods

We enrolled patients who underwent ventricular tachycardia (VT) ablation via the epicardial approach after endocardial ablation failure. After the procedure, MDCT‐derived images of epicardial fat were loaded to the mapping system. Then, all points acquired during sinus rhythm were retrospectively superimposed and analyzed.

4 Results

This study included data from 7 patients (62.5 ± 3.9 years old) who underwent eight epicardial VT ablation procedures. After the procedure, MDCT‐derived images of epicardial fat were registered in eight procedures. Retrospective analysis of 1,595 mapping and 236 ablation points was performed. Of the 1,595 mapping points on the merged electroanatomical and epicardial fat maps, normal voltage area (NVA) and low voltage area (LVA) without fat had lower impedance than those with fat (NVA without fat 182 ± 46 Ω vs. NVA with fat 321 ± 164.0 Ω, P  =  0.001, LVA without fat 164 ± 69 Ω vs. LVA with fat 248 ± 89 Ω, P  =  0.002). Of the 236 ablation points, initial impedance before ablation was higher on epicardial fat than on epicardial LVA without fat (134 ± 16 Ω vs. 156 ± 28 Ω, P  =  0.01).

5 Conclusions

Real time epicardial impedance evaluation may be useful to determine effective epicardial ablation sites and avoid adipose tissue. However, the number of patients in the present study is limited. Further investigation with a large number of patients is needed to confirm our result.     

Heterogeneous regional endocardial repolarization is associated with increased risk for ischemia-dependent ventricular fibrillation after myocardial infarction

Repolarization Heterogeneity and Sudden Death Risk. INTRODUCTION: The aim of this study was to investigate whether the characteristics of endocardial ventricular repolarization are associated with differential risk for sudden death. Prolonged surface QT interval is associated with increased arrhythmic risk after myocardial infarction (MI), but the underlying mechanism of QT prolongation and its relation to lethal arrhythmias are unclear. METHODS AND RESULTS: Ventricular fibrillation (VF) risk was assessed in 12 dogs 1 month after anterior MI during an exercise test coupled with brief circumflex coronary occlusion. Susceptible dogs (n = 5) developed VF during the brief ischemic episode, whereas resistant dogs did not (n = 7). Surface QT interval was measured at rest. Endocardial electroanatomic catheter maps of left ventricular repolarization were obtained in four unique regions identified by echocardiography and compared between groups. Compared to resistant dogs, susceptible dogs were characterized by prolonged surface QT intervals (240 +/- 10 msec vs 222 +/- 7 msec, P = 0.04). In addition, they had lower baroreflex sensitivity (9.7 +/- 1.5 msec/mmHg vs 28 +/- 9.8 msec/mmHg, P < 0.01) and a tachycardic response to acute ischemia suggesting higher propensity for stronger sympathetic reflexes. Surface QT interval prolongation in susceptible dogs was due to a marked heterogeneity of endocardial left ventricular repolarization (239 +/- 42 msec, basal anterior wall vs 197 +/- 35, lateral wall; P < 0.001). Resistant animals had no regional differences in endocardial repolarization. CONCLUSION: Sympathetic activation following MI not only produces adverse structural remodeling but also contributes to adverse electrophysiologic remodeling resulting in heterogeneous ventricular repolarization and in a myocardial substrate conducive to lethal reentrant arrhythmias.     

心内膜和心外膜消融的summit区室性早搏:心电图特征和远期预后

目的]分析summit区室性早搏体表12导联心电图,识别是否存在可以精准判断有效消融靶点的心电图特征。[方法]选择2018年6月—2021年2月期间在冠状窦内或对应的左心室心内膜面行summit区室性早搏射频消融术患者36例,回顾性分析其体表12导联心电图报告。[结果]25例患者的有效消融靶点位于心内膜面的临近部位(心内膜组),余11例患者的有效消融靶点位于心外膜的心大静脉和前室间静脉(GCV-AIV)区(心外膜组)。心内膜组的类本位曲折(ID)显著小于心外膜组,差异有统计学意义(P＝0.022)。心内膜组的最大转折指数(MDI)明显小于心外膜组,差异有统计学意义(P＝0.020)。心内膜组的假性δ波时限显著短于心外膜组,差异有统计学意义(P＝0.004)。随访6～36个月,心外膜组消融成功率为100%(11/11),心内膜组失访1例,余24例患者的消融成功率为87.5%(21/24)。心内膜组亚组分析显示,当假性δ波时限≥25 ms时消融成功率仅为62.5%(5/8),但当假性δ波时限＜25 ms时消融成功率为100%(16/16)。假性δ波时限＜25 ms对心内膜面消融成功预判的灵敏度和特异度分别为94%和72%。[结论]summit区室性早搏心电图上假性δ波时限＜25 ms与心内膜面导管射频消融的成功率密切相关。     

心外膜室性心动过速的心电图特征

心外膜室速的心电图有其共同表现：QRS 时限≥200 ms,但也有部分时限≤120 ms;起始部有假性Δ波≥34 ms;电轴多数左偏,胸前导联移行在 V2以后;V2导联 R 波达峰值时间延长≥85 ms;最短 RS 时间≥121 ms。识别左心室起源的心外膜室速：Ⅰ导联呈 Q 波的基底、心尖部室速;Ⅱ、Ⅲ、aVF 导联无 Q 波的基底部室速;Ⅱ、Ⅲ、aVF 导联呈 Q 波的基底上部、心尖部室速;最大转折指数可识别左室流出道心外膜室速,当最大转折指数≥0．55可识别远离主动脉窦的心外膜室速。识别右心室起源的心外膜室速：Ⅰ导联呈 Q 波且右室前壁导联呈 QS,预示心外膜室速可能性大;Ⅱ、Ⅲ、aVF 导联起始 Q 波,可在同步电生理标测时观察到位于右心室心外膜起源的室速。但不同部位及不同病因的室速又有其特殊性,术前通过体表心电图进行较为精确的定位对室速消融有一定的指导意义。     

Role of programmed ventricular stimulation in patients with idiopathic dilated cardiomyopathy and documented sustained ventricular tachyarrhythmias: inducibility and prognostic value in 102 patients

The role of programmed ventricular stimulation (PVS) in patientsat high risk of sudden death related to idiopathic dilated cardiomyopathy(DCM) is still controversial The possible reason is that moststudy series have been too small or that only a few patientshad documented sustained ventricular tachyarrhythmias. This study therefore, looked at PVS performed in 102 patientswith DCM and documented sustained ventricular tachycardia (VT;n=63) or ventricular fibrillation (VF; n=39). Sustained VT wasinduced in 27 of 63 patients (43%) with documented sustainedVT and in 14 of 39 patients (36%) with documented VF (ns). VFwas induced in nine patients (14%) with a history of sustainedVT and in seven (18%) with a history of VF (ns). At a mean follow-upof 32±15 months, sudden death occurred in 14 (14%) patients,a rate similar in both patients with documented VT and VF (ns).Incidence of sudden death at 36 months was 6% in patients withinducible sustained VT/VF compared to 29% in patients withoutinducible VT/VF (P<0·05) A favourable drug regimen(response to drug and no intolerable side effects) was obtainedby serial drug testing in 25 of all 102 patients (25%). A cardioverterdefibrillator (ICD) was implanted in 32 patients, in 63% ofwhom discharges were observed during 18±11 months offollow-up; only one patient (3%) died suddenly. Thus, in patients with DCM, there was no relationship betweendocumented and inducible ventricular tachzyarrhythmias, andinitiation of sustained VT or VF had little prognostic valuefor the prediction of subsequent sudden death. Wherever antiarrhythmic drug therapy was of limited value, implantationof an ICD may improve the prognosis of these high risk patients.     

Ablation of epicardial macroreentrant ventricular tachycardia associated with idiopathic nonischemic dilated cardiomyopathy by a percutaneous transthoracic approach

Characterization of the substrate and mechanism of epicardial ventricular tachycardia (VT) associated with idiopathic nonischemic dilated cardiomyopathy is limited. We report a case of successful mapping and ablation of an epicardial VT by a percutaneous transthoracic approach in a patient with idiopathic dilated cardiomyopathy, frequent VT, and previously unsuccessful endocardial ablation. Evidence of myocardial scar was limited to the epicardium. Electroanatomic and entrainment mapping defined a figure-of-eight macroreentrant circuit within the epicardial scar. VT terminated at the onset of low-power radiofrequency application to the central isthmus of the circuit. VT was no longer induced and did not recur during long-term follow-up.     

Value of induction of pleomorphic ventricular tachycardia during programmed stimulation

The morphology of the first documented, the recurrent and theinduced ventricular tachycardia were studied in 41 patientswith an old myocardial infarction and documented sustained ventriculartachycardia. During a mean follow-up of29 ± 11 monthsrecurrent ventricular tachycardia was present in 24 of 41 patientswith the same morphology as the first ventricular tachycardiain nine (37.5%) and a different morphology in 15 patients (62.5%).Ventricular tachycardia with the same morphology as the spontaneousventricular tachycardia were induced without significant differencesbetween patients with recurrent events and those without. However,multiple morphologies of ventricular tachycardia (pleomorphism)were induced more frequently in patients with subsequent recurrenceof ventricular tachycardia (off drugs: 9 of 13, 69%, on drugs:14 of 23, 61%) than in patients without (off drugs: 4 of 10,40%, on drugs: 2 of 11,18%) (P <0.05). Pleomorphism of ventricular tachycardia induced during programmedstimulation identifies patients at a higher risk of subsequentrecurrent events. Recurrent ventricular tachycardia has a differentmorphology than the first one in two thirds of patients.     

Value of high-density endocardial and epicardial mapping for catheter ablation of hemodynamically unstable ventricular tachycardia

BACKGROUND: Percutaneous epicardial mapping has been used for ablation of recurrent ventricular tachycardia (VT). OBJECTIVES: The purpose of this study was to use a combined epicardial and endocardial mapping strategy to delineate the myocardial substrate for recurrent VT in both ischemic (n = 12) and nonischemic cardiomyopathy (n = 8), and to define the role of epicardial ablation. METHODS: Electroanatomic mapping was performed in 20 patients. High-density voltage maps were obtained by acquiring both endocardial and epicardial electrograms. Electrograms derived from six patients with structurally normal hearts were used as controls. A total of 26 VTs were targeted in the 20 patients. RESULTS: Most VTs (23/26 [88.5%]) were hemodynamically unstable. In patients with ischemic cardiomyopathy, the extent of endocardial scar was greater than epicardial scar. A definable pattern of scar could not be demonstrated in nonischemic cardiomyopathy. Pathologic examination of explanted hearts in two patients with nonischemic cardiomyopathy demonstrated that low-voltage areas were not always predictive of scarred myocardium. A substrate-based approach was used for catheter ablation. Catheter ablation was performed on the endocardium in all patients; additional epicardial delivery of radiofrequency energy was required in 8 (40%) of 20 patients for successful ablation. During follow-up (12 +/- 4 months), 15 (75%) of 20 patients have been arrhythmia-free. CONCLUSION: Patients with ischemic cardiomyopathy tend to have a larger endocardial than epicardial scar. Use of epicardial and endocardial electroanatomic mapping to define the full extent of myocardial scars allows successful catheter ablation in patients with hemodynamically unstable VTs.     

Normal atrial activation and voltage during sinus rhythm in the human heart: an endocardial and epicardial mapping study in patients with a history of atrial fibrillation

Background: The three-dimensional contributions to human atrial activation in sinus rhythm have not been specifically characterized. We evaluated the sequence of endocardial and epicardial activation and voltage of the atria during normal sinus rhythm.
Methods and Results: The study group includes 35 patients with history of symptomatic atrial fibrillation. Prior to catheter ablation of atrial fibrillation, we performed multielectrode electroanatomic mapping during sinus rhythm, endocardially of the RA, LA, and coronary sinus (CS) and, in 10 patients, epicardially of the transverse sinus and oblique sinus. Following activation of the atrial region of the sinus node, the epicardial transverse sinus was activated 11 ± 18 msec later, while the earliest endocardial LA activation occurred in the region of Bachmann's bundle at 31 ± 13 msec, significantly earlier than the earliest epicardial LA activation of the oblique sinus at 54 ± 10 msec (P < 0.002). The posterior LA revealed complex types of activation in 66% of patients analyzed, due to the convergence of wavefront propagation from the CS, oblique sinus, and endocardial LA. Bipolar voltage measurements revealed significantly higher values for the epicardium (mean 3.05 ± 1.31 mv) than for the endocardium (mean 1.65 ± 0.75 mv), P < 0.0001 between both groups.
Conclusions: In sinus rhythm, we have characterized endocardial and epicardial atrial activation and voltage, and provide an analysis and understanding of the genesis of the P wave complex in humans.     

Caudocranial transseptal approach for placement of endocardial left ventricular leads

Cardiac resynchronization therapy (CRT) is associated with improvement in the quality of life, hospitalization rates, and mortality in patients with left ventricular dysfunction and evidence of the right ventricle‐left ventricle (RV‐LV) desynchrony. Implant failure rates and patient outcomes have improved with the advent of quadripolar leads, yet alternatives to traditional coronary sinus (CS) LV lead placement is sought for in a subset of advanced heart failure patients with difficult CS anatomy, phrenic nerve stimulation or in nonresponders. Endocardial left ventricular pacing (EnLVP) in chronically anticoagulated patients has been reported as an alternative using different approaches, techniques, and tools with acceptable short and long term adverse events. We present a case of successful EnLVP achieved for CRT using standard techniques and commonly available tools in a patient on chronic direct oral anticoagulation with recurrent heart failure admissions who failed traditional epicardial LV pacing.