Unusual features of right and left idiopathic ventricular tachycardia abolished by radiofrequency catheter ablation

Two unusual cases are presented with idiopathic right and left ventricular tachycardia (IVT) with intriguing clinical and electrophysiological characteristics. The first patient with a sustained IVT of right ventricular outflow tract origin, and an electrophysiological mechanism suggesting reentry, had been resuscitated from cardiac arrest. The second patient had an IVT with a left bundle branch block morphology, which originated from the basal-septal region of the left ventricle (left ventricular outflow tract tachycardia). Both patients were cured with radiofrequency catheter ablation, guided by endocardial activation sequence and pace mapping.     

Verapamil-sensitive left anterior fascicular ventricular tachycardia: results of radiofrequency ablation in six patients

INTRODUCTION: Verapamil-sensitive left ventricular tachycardia (VT) with a right bundle branch block (RBBB) configuration and left-axis deviation has been demonstrated to arise from the left posterior fascicle, and can be cured by catheter ablation guided by Purkinje potentials. Verapamil-sensitive VT with an RBBB configuration and right-axis deviation is rare, and may originate in the left anterior fascicle. METHODS AND RESULTS: Six patients (five men and one woman, mean age 54+/-15 years) with a history of sustained VT with an RBBB configuration and right-axis deviation underwent electrophysiologic study and radiofrequency (RF) ablation. VT was slowed and terminated by intravenous administration of verapamil in all six patients. Left ventricular endocardial mapping during VT identified the earliest ventricular activation in the anterolateral wall of the left ventricle in all patients. RF current delivered to this site suppressed the VT in three patients (ablation at the VT exit). The fused Purkinje potential was recorded at that site, and preceded the QRS complex by 35, 30, and 20 msec, with pace mapping showing an optimal match between the paced rhythm and the clinical VT. In the remaining three patients, RF catheter ablation at the site of the earliest ventricular activation was unsuccessful. In these three patients, Purkinje potential was recorded in the diastolic phase during VT at the mid-anterior left ventricular septum. The Purkinje potential preceded the QRS during VT by 66, 56, and 63 msec, and catheter ablation at these sites was successful (ablation at the zone of slow conduction). During 19 to 46 months of follow-up (mean 32+/-9 months), one patient in the group of ablation at the VT exit had sustained VT with a left bundle branch block configuration and an inferior axis, and one patient in the group of ablation at the zone of slow conduction experienced typical idiopathic VT with an RBBB configuration and left-axis deviation. CONCLUSION: Verapamil-sensitive VT with an RBBB configuration and right-axis deviation originates close to the anterior fascicle. RF catheter ablation can be performed successfully from the VT exit site or the zone of slow conduction where the Purkinje potential was recorded in the diastolic phase.     

Adenosine-sensitive ventricular tachycardia from the anterobasal left ventricle

OBJECTIVES: This study demonstrates that exercise-provocable tachycardia resembling right ventricular outflow tract tachycardia may originate from the anterobasal left ventricle. BACKGROUND: Reentry is the operative mechanism of idiopathic left ventricular tachycardia, with a QRS complex of right bundle branch block and superior axis that is responsive to verapamil but not adenosine. Whether some mechanism other than reentry is operative in some idiopathic left ventricular tachycardias is unclear. METHODS: In 4 of 53 consecutive patients with idiopathic left ventricular tachycardia, the tachycardia was sensitive to adenosine. These four patients were women 63, 61, 61 and 31 years old and were the subjects of the present study. RESULTS: In all four patients, spontaneous tachycardia was related to exercise or emotional stress. The tachycardia displayed atypical left (one patient) or right (three patients) bundle branch block with an inferior axis and marked variation in cycle length. An intravenous bolus of adenosine triphosphate (10 to 20 mg) terminated tachycardia in all four patients. Tachycardia was terminated or prevented in three patients given intravenous or oral verapamil. Atrial or ventricular incremental or extrastimulus testing induced tachycardia in all four patients (three with, one without isoproterenol infusion). Electrically induced tachycardia also demonstrated marked variation in cycle length, which ranged from 230 to 390 ms. Entrainment was not demonstrable with overdrive pacing from multiple sites. Endocardial mapping during tachycardia revealed that the earliest activations were registered 25, 40, 35 and 50 ms before onset of the QRS complex, respectively, from the anterior aspect of the left ventricle just below the mitral annulus, adjacent to the left ventricular outflow tract. High frequency Purkinje spikes were not recorded at this site. Radiofrequency current delivered to this site successfully ablated the tachycardia in three of the four patients. CONCLUSIONS: Exercise-provocable, catecholamine-mediated, verapamil-responsive, adenosine-sensitive ventricular tachycardia may arise from the anterobasal left ventricle adjacent to the outflow tract.     

Significance of morphological abnormalities detected by MRI in patients undergoing successful ablation of right ventricular outflow tract tachycardia

BACKGROUND: MRI can demonstrate subtle morphological changes of the right ventricle in patients with idiopathic right ventricular outflow tract tachycardia (RVOT). The present study examines the incidence and significance of right ventricular (RV) abnormalities detected by MRI with respect to the site of successful radiofrequency catheter ablation of the clinical tachycardia. METHODS AND RESULTS: The study population comprised 20 patients (mean age, 40+/-12 years) undergoing elimination of recurrent RVOT by radiofrequency catheter ablation. MRI studies were performed before ablation to assess RV volumes and function, as well as structural abnormalities of the RV myocardium. Ten healthy age- and sex-matched subjects served as control subjects. The successful ablation sites, as documented by radiographs of the catheter position, were compared with MRI findings. Patients with RVOT showed no difference in respect to RV volumes and ejection fractions compared with control subjects. Whereas RV abnormalities were limited to prominent fatty deposits of the right atrioventricular groove extending into the inlet portion of the RV wall in 2 of 10 control subjects, MRI studies demonstrated morphological changes of the RV free wall in 13 (65%) of 20 patients with RVOT, including presence of fatty tissue (n=5), wall thinning (n=9), and dyskinetic wall segments (n=4). Eight of these patients had additional fat deposits, thinning, or a saccular aneurysm in the RV outflow tract, corresponding with the ablation site in 6 patients. CONCLUSIONS: In RVOT, structural abnormalities of the right ventricle can be detected in a substantial number of patients despite normal RV volumes and global function. MRI abnormalities within the RV outflow tract are significantly associated with the origin of tachycardia.     

Successful radiofrequency ablation of idiopathic left ventricular tachycardia at a site away from the tachycardia exit

OBJECTIVES: This study sought to assess the possibility of ablating verapamil-responsive idiopathic left ventricular tachycardia at a site distant from the tachycardia exit and thus to define the tachycardia circuit. BACKGROUND: The nature of the reentry circuit in idiopathic left ventricular tachycardia is unclear. If the circuit is of considerable size, then it should be possible to ablate the tachycardia at a site distant from the exit site. METHODS: Electrophysiologic studies and radiofrequency ablation were performed in 27 consecutive patients with verapamil-responsive idiopathic left ventricular tachycardia. In all 27 patients, the tachycardia exit site was defined as the site where the earliest Purkinje potential was recorded > or = 25 ms before the onset of the QRS complex during the tachycardia and where the pace map QRS complex resembled that during the tachycardia. A potential ablation site other than the exit site was then sought around the midseptum, proximal to the exit site. At such sites the tachycardia could be terminated transiently by pressure applied to the catheter tip, without induction of ventricular ectopic beats. RESULTS: The potential ablation site, other than the tachycardia exit site, was identified in seven male patients (mean [+/-SD] age 31 +/- 12 years, range 13 to 52). Application of the radiofrequency current at this site resulted in termination of the tachycardia within 1 to 5 s (mean 2.9 +/- 1.6), and successful ablation of the tachycardia was achieved in all seven patients (success rate 100%, 95% exact confidence interval 0.5898 to 1). The mean distance between the ablation site and the tachycardia exit site was 3.1 +/- 0.7 cm (range 2.0 to 4.0). A presystolic Purkinje spike was recorded 14 +/- 5 ms (range 8 to 20) before the onset of the QRS complex during the tachycardia. During the follow-up period of 24 +/- 11 months (range 12 to 39), there was no recurrence of tachycardia in these seven patients. CONCLUSIONS: Successful ablation of idiopathic left ventricular tachycardia can be achieved at sites away from the tachycardia exit site in some patients. This finding suggests that the reentry circuit is likely to be of considerable size, encompassing the middle, inferior and lower aspects of the left interventricular septum.     

Radiofrequency catheter ablation of ventricular tachycardia in 26 patients

Electrophysiology study and radiofrequency catheter ablation (RFCA) were performed in 26 patients with refractory sustained ventricular tachycardia (VT). After induction of VT, 12-lead electrocardiogram (ECG) was recorded and QRS morphology and axis of induced VT were studied to identify the origin of VT. The precise site of VT origin were localized by pace mapping and activation mapping carefully. RF energy was delivered through a big-tip deflectable electrode catheter when the earliest site of endocardial activation and a high-frequency and low-amplitude potential of Purkinje fiber, preceding surface QRS by more than 25 ms, were identified and/or a pace map was obtained showing identical QRS complexes in at least 11 of 12 ECG leads. VTs were ablated successfully in 24 of 26 patients (success rate was 92%). For successful ablation, it is essential that the pace map QRS morphology in 12 leads should be identical with that in spontaneous or induced VT as far as possible in performing pace mapping. Pace mapping is safe, simple and has no unfavourable effect hemodynamics although it takes longer time. Activation mapping takes shorter time and has a high success rate. QRS configuration in spontaneous VT can help to localize the site of VT origin. Deliberate mapping at the site suggested to bo the origin of VT by surface ECG can shorten the duration of mapping and increase the success rate of RFCA. RFCA of VT in patients without structural heart disease is effective, safe, and has a high success rate, so it may be considered as an early therapy for these patients.     

The significance of electrocardiography in locating original sites of ventricular tachycardia

The sites of origin of ventricular tachycardia (VT) in 12 patients were located by ECG during the episode and further confirmed by catheter mapping. The results showed that there were 14 sites of origin of VT in the 12 patients from ECG in which 1 site was incompletely mapped by catheter and 12 of the other 13 original sites were confirmed by the catheter endocardial or epicardial mapping. Of the 12 original sites of VT, the locating of 11 ones were completely consistent with those from ECG, which was 84.6% of the 13 original sites. Moreover, 8 of the 12 patients had been successfully treated by catheter direct or radiofrequency current ablation and 1 of the 12 by successful surgical operation. Thus, the original sites of VT located by ECG was reliable and could shorten the time of catheter mapping during non-pharmacological therapy of VT.     

Radiofrequency current caused slowing of non-reentrant idiopathic right ventricular tachycardia originating from a wide arrhythmogenic area

Radiofrequency catheter ablation was attempted in a patient with non-reentrant idiopathic right ventricular tachycardia (VT). Endocardial mapping indicated that the VT originated in the outflow tract of the right ventricle; however, an electrogram with an almost the identical activation time was recorded from an area extending to 1.0 x 2.0 cm. Each application of radiofrequency current within the area terminated VT, but a progressively slower VT with the same QRS configuration was induced until the area was covered by separate radiofrequency lesions. A progressive prolongation of VT cycle length might be related to a residual arrhythmogenic myocardium. Termination and slowing of the VT rate can be a hallmark of efficacy of each radiofrequency lesion.     

Right ventricular radiofrequency ablation of ventricular tachycardia after myocardial infarction

Radiofrequency transcatheter ablation of ventricular tachycardia in the setting of a prior myocardial infarction is typically performed with application of energy to the left ventricular endocardium. In this article, two cases are described in which successful radiofrequency transcatheter ablation of ventricular tachycardia occurred with energy delivery to the right ventricular septum after failed ablation attempts from the left ventricle. Both patients had tachycardias with a left bundle branch block morphology and markedly presystolic activity recorded from the right ventricular septum. Right ventricular septal activation mapping during ventricular tachycardia should be performed in patients with left bundle branch block tachycardia morphology and coronary artery disease to maximize efficacy of the catheter ablation procedure.     

Catheter ablation of incessant ventricular tachycardia: acute and long-term results

SUBJECTS: Seventeen patients with incessant ventricular tachycardia refractory to anti-arrhythmic therapy underwent catheter ablation between 1987 and 1993. Fifteen patients had coronary heart disease and two had dilated cardiomyopathy. The mean age of the patients was 65 +/- 8 and the mean left ventricular ejection fraction was 31 +/- 9%. METHODS: Ablation sites were selected on the basis of endocardial activation mapping, concealed entrainment or bundle branch mapping. Catheter ablation was performed with direct current in nine patients and with radiofrequency energy in eight patients. Incessant ventricular tachycardia was terminated by catheter ablation in all 17 patients. RESULTS: One patient died after the ablation procedure due to pericardial tamponade. During electrophysiological testing 5-14 days later, 7 of 16 patients (44%) had inducible sustained or non-sustained ventricular tachycardia. Five of them underwent implantation of an automatic cardioverter/defibrillator, and three of these experienced discharges of the device during a mean follow-up of 30 +/- 12 months. another patient underwent implantation of a cardioverter/defibrillator after spontaneous recurrence of ventricular tachycardia. Out of the nine patients without inducible ventricular tachycardia, one died as a result of sudden cardiac death, and another had spontaneous ventricular tachycardia. Thus, ventricular tachycardia recurred clinically in 6 of 16 patients (38%), in whom ventricular tachycardia with the same morphology as that of the ablated ventricular tachycardia could be determined only in one patient. CONCLUSION: Catheter ablation is the method of choice for the emergency treatment of patients with incessant ventricular tachycardia. Due to the high risk of recurrence, additional anti-arrhythmic management, such as the implantation of a cardioverter/defibrillator, has to be considered.     

Familial bilateral blepharoptosis and subvalvular aortic stenosis

PURPOSE: To select ideal radiologic projections for mapping and ablation of tachycardias of right ventricular outflow tract (RVOT). METHODS: Ten hearts from human corpses were studied utilizing radiopaque material to identify the pulmonary valve and three distinct sites on this valve: septal anterior (A), septal posterior (P) and free-wall (L). Next, the hearts were filmed in the frontal plane and in oblique projections with 15 degrees increments to the right and to the left. The projections in which the sites were lateralized on the valve, eased radiologic interpretation and were considered ideal for mapping and ablation. Depending on the proximity of the sites to the lateral extremes of the pulmonary valve, the projections were considered ideal ( ), intermediary (++) and inadequate (+). RESULTS: Projections [table: see text] CONCLUSION: The A site of RVOT was best indicated in the 60 and 45 degrees left anterior oblique projections; the 0 degree postero anterior projection was best for mapping the P site; the L region was best explored in the 60 degrees right anterior oblique projection.     

Analysis of the immunoglobulin heavy-chain gene rearrangement providing molecular evidence of second lymphoma in a patient in apparent relapse after autotransplantation

Thirteen consecutive patients with idiopathic ventricular tachycardia underwent radiofrequency catheter ablation. This group included 9 idopathic left ventricular tachycardia (ILVT) and 4 idiopathic right ventricular tachycardia (IRVT). Five ILVT patients with left axis deviation and one with right axis deviation were ablated successfully. By pace mapping, two IRVT patients with ventricular tachycardia originating from right ventricular out-flow tract were ablated. No complications occured. By means of follow-up of 3-22 months one case showed recurrence with successful reablation. It indicates that radiofrequency catheter ablation therapy is an effective and safe procedure in patients with idiopathic ventricular tachycardia.     

Surgical treatment of ventricular tachycardia after surgical repair of tetralogy of Fallot. Relation between intraoperative mapping and histological findings

BACKGROUND: The mechanism of ventricular tachycardia (VT) after correction of tetralogy of Fallot (TF) is poorly understood. The purpose of this study was to examine the histopathology of the arrhythmogenic area detected by intraoperative mapping. METHODS AND RESULTS: The patients were three men who underwent radical surgery for TF at age 3, 3, or 5 years, respectively. VT developed at 8, 9, or 11 years, respectively, after surgery, and shock developed during VT in every case. The ECG revealed monomorphic VT in two cases and polymorphic VT in one case. Induction of VT resulted in a wide left-axis deviation-pattern QRS with cycle lengths varying between 260 and 330 milliseconds. The VT origin was identified at the right ventricular outflow tract (RVOT). A radical operation was performed with the patient under cardiopulmonary bypass. On epicardial mapping, delayed activation of the RVOT was recorded during sinus rhythm, and clockwise circus movement of the macroreentry current during VT on the right ventricular free wall was documented in each case. The VTs were treated successfully by surgical resection and cryoablation of the myocardium. In every patient, histology of the myocardial specimens showed degeneration, adiposis, fibrosis, inflammatory cell infiltration, and scattered myocyte islets. These lesions corresponded anatomically to the area of myocardium in which delayed activation was evident during epicardial mapping. CONCLUSIONS: The results of this study indicate that patients with VT after radical correction of the TF have abnormal histopathological findings at the site of the prior right ventriculotomy scar. These lesions were noted within the region of delayed activation found during epicardial mapping and were found to be a part of the reentrant circuit.     

Catheter ablation of ventricular tachycardia after myocardial infarction: relation of endocardial sinus rhythm late potentials to the reentry circuit

OBJECTIVES: We sought to determine whether endocardial late potentials during sinus rhythm are associated with reentry circuit sites during ventricular tachycardia (VT). BACKGROUND: During sinus rhythm, slow conduction through an old infarct region may depolarize tissue after the end of the QRS complex. Such slow conduction regions can cause reentry. METHODS: Endocardial catheter mapping and radiofrequency ablation were performed in 24 patients with VT late after myocardial infarction. We selected for analysis a total of 103 sites where the electrogram was recorded during sinus rhythm and, without moving the catheter, VT was initiated and radiofrequency current applied in an attempt to terminate VT. RESULTS: Late potentials were present at 34 sites (33%). During pace mapping, the stimulus-QRS complex was longer at late potential sites, consistent with slow conduction, than at sites without late potentials (p < 0.0001). Late potentials were present at 15 (71%) of 21 sites classified as central or proximal in the reentry circuit based on entrainment, but also occurred frequently at bystander sites (13 [33%] of 39) and were often absent at the reentry circuit exit (3 [23%] of 13). Late potentials were present at 20 (54%) of 37 sites where ablation terminated VT, compared with 14 (21%) of 66 sites where ablation did not terminate VT (p = 0.004). Ablation decreased the amplitude of the late potentials present at sites where ablation terminated VT. CONCLUSIONS: Although sites with sinus rhythm late potentials often participate in VT reentry circuits, many reentry circuit sites do not have late potentials. Late potentials can also arise from bystander regions. Late potentials may help identify abnormal regions in sinus rhythm but cannot replace mapping during induced VT to guide ablation.     

Return cycle mapping after entrainment of ventricular tachycardia

BACKGROUND: The central common pathway, which is the target for ablation in reentrant ventricular tachycardia, can be localized by entrainment mapping techniques. However, localization of the pathway is not always possible because of the elevated pacing threshold and the low voltage and fractionated potentials at the pathway. We examined whether return cycle mapping after entrainment localizes the pathway without pacing at the pathway or recording the potentials from the pathway and determined the required electrode resolution to localize the pathway. METHODS AND RESULTS: Epicardial mapping was performed with 253 unipolar electrodes during and after entrainment of 13 morphologies of ventricular tachycardia that were induced in dogs 4 days after infarction. The return cycle was calculated by subtracting the first activation time from the second activation time after the last stimulus and the return cycle distribution map was constructed for each stimulation site. The return cycle isochrones equal to the ventricular tachycardia cycle length converged on the lines of conduction block irrespective of the stimulation site, and the central common pathway was localized at the region between the intersections of the return cycle isochrones after entrainment from different stimulation sites. The potentials from the central common pathway were not required to localize the pathway, and the mapping accuracy did not change with or without analysis of the potentials from the pathway. According to the correlation between the electrode resolution and the mapping accuracy, an interelectrode distance of 8.5 mm was estimated as sufficient resolution for successful tachycardia termination during radiofrequency ablation guided by return cycle mapping. CONCLUSIONS: Return cycle mapping after entrainment localizes the central common pathway without pacing at the pathway or recording the potentials from the pathway. This new mapping technique could improve the success rate of the ablative procedures.     

Radiofrequency catheter ablation of sustained monomorphic ventricular tachycardia in hypertrophic cardiomyopathy

INTRODUCTION: Incessant monomorphic ventricular tachycardia (VT) with a right bundle branch block morphology and a northwest axis is a rare arrhythmic complication in a patient with hypertrophic cardiomyopathy and apical left ventricular aneurysm. METHODS AND RESULTS: The origin of this VT was localized using the following criteria: the presence of entrainment without fusion, equal intervals from the stimulus to the beginning of the QRS complex and from the electrogram to the QRS complex during VT, and the first postpacing interval identical to the tachycardia cycle length. Radiofrequency energy applied to the septoapical part of the apical left ventricular aneurysm terminated the tachycardia within 2 seconds. CONCLUSION: Using criteria to guide radiofrequency (RF) ablation of VT in patients with coronary artery disease, an incessant monomorphic VT in a patient with hypertrophic cardiomyopathy was successfully ablated.     

Catheter ablation of incessant ventricular tachycardia

Emergency catheter ablation of ventricular tachycardia was performed in 22 patients. All patients had incessant ventricular tachycardia that persisted for > or = 12 h/day and was only transiently terminated by stimulation techniques, anti-arrhythmic drugs or cardioversion. Radiofrequency catheter ablation was carried out using entrainment criteria as well as endocardial activation mapping. Ventricular tachycardia was terminated in 91% of cases, one patient underwent map-guided surgery and the remaining patient was managed by anti-arrhythmic drugs. After the initial ablation procedure 3 of the 20 patients who could be acutely managed died in hospital: one patient in refractory heart failure 24 h following ablation, one patient suddenly 10 days following ablation on the ward and another patient 4 weeks following ablation because of septicemia. Four patients underwent elective implantation of a cardioverter-defibrillator because of inducible ventricular tachycardia, and another patient underwent elective map-guided surgery. Overall, 12 patients were discharged without any additional non-pharmacologic intervention; 5 of them were free of anti-arrhythmic drugs and 7 patients had previously received ineffective medication including continuation of amiodarone in 3 patients. These results indicate that radiofrequency catheter ablation may play a role in the treatment of patients with incessant ventricular tachycardia. Thus, non-pharmacologic management of incessant ventricular tachycardia is associated with a high hospital mortality rate especially in surgically treated patients. Catheter ablation using radiofrequency current is the preferred approach for acute palliation.     

Two cases of ventricular parasystole associated with ventricular tachycardia

In two patients, ventricular parasystole (VP) was associated with ventricular tachycardia (VT), and in one patient, catheter ablation was successful. In patient 1, with dilated cardiomyopathy, VP led to VT, which converted to ventricular fibrillation. In patient 2, VP led to symptomatic nonsustained polymorphic VT. The origin of parasystolic focus was determined by endocardial mapping, and a radiofrequency current was delivered to patient 2. Both VP and VT disappeared immediately, and no recurrence has been observed during a follow-up of 8 months. Catheter ablation to the parasystolic focus was effective and a relationship between VP and VT was strongly suggested.     

Morphological characteristics of layer II projection neurons in the rat medial entorhinal cortex

Idiopathic left ventricular tachycardia (ILVT) differs from idiopathic right ventricular outflow tract (RVOT) tachycardia with respect to mechanism and pharmacologic sensitivity. ILVT can be categorized into three subgroups. The most prevalent form, verapamil-sensitive intrafascicular tachycardia, originates in the region of left posterior fascicle of the left bundle. This tachycardia is adenosine insensitive, demonstrates entrainment, and is thought to be due to reentry. The tachycardia is most often ablated in the region of the posteroinferior interventricular septum. A second type of ILVT is a form analogous to adenosine-sensitive RVOT tachycardia. This tachycardia appears to originate from deep within the interventricular septum and exits from the left side of the septum. This form of VT also responds to verapamil and is thought to be due to cAMP-mediated triggered activity. A third form of ILVT is propranolol sensitive. It is neither or initiated or terminated by programmed stimulation, does not terminate with verapamil, and is transiently suppressed by adenosine, responses consistent with an automatic mechanism. Recognition of the heterogeneity of ILVT and its unique characteristics should facilitate appropriate diagnosis and therapy in this group of patients.     

Catheter ablation for ventricular tachycardia from a diverticulum at the right ventricular outflow tract

A case is presented of a 73-year-old man with drug resistant ventricular tachycardia that originated from the right ventricular outflow tract. A right ventriculogram showed a diverticulum in the interventricular septum at the right ventricular outflow tract. Low energy radiofrequency catheter ablation within the diverticulum was performed successfully and safely.