Entrapment of a guide wire by the Chiari network in a patient with ablated idiopathic ventricular tachycardia.

Using a guide wire before insertion of a sheath is a common procedure with infrequent complications. We report an unusual case of a guide wire having been entrapped by the Chiari network prior to an intended radiofrequency ablation procedure, and which could be observed using intracardiac echocardiography. Using transthoracic echocardiography prior to ablation, this patient had been shown to have a relatively large Chiari network. We caution against using a long guide wire in patients with a large Chiari network.

Subthreshold stimulation in three types of reentrant supraventricular tachycardia: correlation with the results of catheter ablation.

The effects of subthreshold stimulation (STS) by direct current were investigated in 20 patients with atrioventricular nodal reentrant tachycardia (AVNRT), 27 with atrioventricular reentrant tachycardia (AVRT) and 3 with idiopathic atrial reentrant tachycardia (IART) STS was delivered to each eligible site for ablation prior to radiofrequency application. STS was defined as 'positive' if it could terminate the tachycardia or disrupt the conduction of accessory pathways without myocardial capture and defined as 'negative' if it could not. Radiofrequency ablation was performed irrespective of a positive or negative result from STS and was successful in all 50 patients. Among the 50 successful ablation sites, STS was positive at 26 sites (11 sites in AVNRT, 12 in AVRT and 3 in IART). STS was positive at 4 sites where ablation failed in 3 patients with AVRT and was negative at 8 sites where ablation was successful in 4 patients with AVNRT and 4 with AVRT. The positive and negative predictive value of STS for the detection of the optimal ablation site were, respectively, 100% and 74% in AVNRT, 73% and 72% in AVRT, and both 100% in IART STS-guided mapping is a specific method to predict the successful catheter ablation of reentrant supraventricular tachycardia.

Influence of right atrial structure on outcome of radio-frequency catheter ablation for common atrial flutter.

Radiofrequency catheter ablation (RFCA) targeting the cavotricuspid isthmus is usually an effective treatment for common atrial flutter (AFL), except in a small subset of patients and the reason for this has yet to be elucidated. The present study investigated the relationship between the outcome of RFCA for common AFL and the anatomy of the right atrium as seen on angiography. Twenty consecutive patients who underwent RFCA for common AFL were divided into 2 groups according to the results of RFCA. Group A comprised 13 patients whose AFL was abolished, fulfilling the criteria of success by the conventional catheter approach, and group B comprised 7 patients whose AFL could not be abolished according to the criteria for success (n=4) or was abolished following an additional superior vena cava approach (n=3). On angiography, the cavotricuspid isthmus was longer (3.5+/-0.5 vs 2.2+/-0.6 cm) and deeper (0.94+/-0.35 vs 0.49+/-0.19 cm) in group B than in group A (both p<0.01). The height of the eustachian valve was also greater in group B than in group A (1.4+/-1.1 vs 0.48+/-0.48 cm, p<0.02). These results suggest that the anatomical structure of the cavotricuspid isthmus affects the outcome of RFCA for common AFL.

In vivo and in vitro study of radio-frequency application with a new long linear probe: implication for the maze operation.

BACKGROUND: The maze operation for atrial fibrillation is effective but highly invasive. We tested, both in vitro and in vivo, a new technique for creating long linear atrial lesions with a custom-made, 25-mm long, stainless-steel, linear probe and a corresponding 500-kHz generator for assistance in the maze operation. METHODS: In the in vitro study with the isolated canine atria, the power of the delivered radio-frequency energy and the saline irrigating flow rate were changed independently, and the sizes of the lesions were measured. In the in vivo study radio-frequency energy was delivered to 4 portions (ie, the smooth and trabeculated portions of the right and left atria). The sizes of the lesions were measured, and the histologic features of the lesions were examined. Electrical isolation of the right atrial appendage from the remaining right atrium was attempted by using this linear probe. RESULTS: In the in vitro study the size of the lesion became larger as the delivered power was increased, although the lesion was limited when the flow rate was high. In the in vivo study the size of the lesion was equal at the 4 different sites. Histologic examinations demonstrated linear and transmural lesions, and electrophysiologic examinations revealed conduction block between the right atrial appendage and the remaining right atrium. CONCLUSIONS: The new original long linear probe was effective for creating transmural linear atrial lesions with the irrigation method, presenting the possibility of an intraoperative technique that mimics the maze procedure.

Radiofrequency catheter ablation from the left sinus of Valsalva in a patient with idiopathic ventricular tachycardia.

We report the case of a 54-year-old woman with idiopathic VT originating in the left ventricular outflow tract. She initially presented with palpitations and light-headedness. The morphology of the PVCs exhibited an inferior axis and tall R waves were noted in all the precordial leads. Spontaneous PVCs were transiently terminated by an intravenous injection of adenosine triphosphate. Radiofrequency catheter ablation from the left sinus of Valsalva successfully abolished the PVCs and the VT.

Severe thrombocytopenia caused by digitoxin intoxication in a patient with heart failure associated with Sjögren's syndrome.

Congestive heart failure (CHF) related to Sjögren's syndrome is extremely rare. This report concerns a patient who presented with CHF and severe thrombocytopenia (5,000/microl). Serum concentrations of K, Mg and digitoxin were 3.2mmol/L, 1.4mg/L and 57.2ng/ml, respectively. Digitoxin intoxication was evident, seemingly evoked by hypokalemia, hypomagnesemia, hepatorenal dysfunction and hypothyroidism. The severe thrombocytopenia was considered to have been caused by this intoxication, as it disappeared soon after the digitoxin was discontinued and potassium was supplemented.

Radiofrequency catheter ablation of upper septal idiopathic left ventricular tachycardia exhibiting left bundle branch block morphology.

Idiopathic left ventricular (LV) tachycardia usually exhibits right bundle branch block morphology. There are only a few sporadic cases that exhibit left bundle branch block (LBBB) morphology. We report a patient whose QRS complex during ventricular tachycardia (VT) was relatively narrow (100 msec) and exhibited LBBB (precordial R wave transition between V3 and V4) and a normal frontal plane axis. This VT was ablated successfully by radiofrequency current applied to the LV upper septum, where the earliest endocardial activation was recorded.

Heart rate variability analysis of patients with idiopathic left ventricular outflow tract tachycardia: role of triggered activity.

There have been several reports with respect to idiopathic ventricular tachycardias (VTs) originating from the left ventricular outflow tract (LVOT). A previous report suggested that triggered activity plays a partial role in idiopathic LVOT tachycardia from the electrophysiological as well as the electropharmacological viewpoint. However, the exact role of triggered activity in this type of VT remains unknown. In the present study the relationship of the frequency of premature ventricular contractions (PVCs) and heart rate was examined and heart rate variability (HRV) was analyzed in 2 cases of LVOT tachycardia using 24-h Holter electrocardiographic (ECG) monitoring. The relation between the PVCs frequency and heart rate showed a persistently positive correlation, indicating frequent PVCs as heart rate increased. In HRV analysis, NN50(%), a time-domain variable of parasympathetic activity, showed no change prior to ventricular arrhythmias. In frequency-domain analysis of HRV, the high frequency (HF) component tended to fall prior to repetitive PVCs and VTs. The ratio of the low frequency to high frequency (LF/HF) components increased prior to single PVCs, repetitive PVCs and VTs. Sympathetic predominance predisposes the genesis of these kinds of arrhythmias originating from the LVOT and it is suggested that triggered activity plays an important role in LVOT tachycardia, at least in its initiation.

Experimental ablation study using a new long linear probe in isolated porcine hearts.

We studied a new technique for creating long linear lesions in hearts using a custom-made linear probe. Radiofrequency (RF) energy applications using a 25-mm long stainless steel linear probe and a corresponding 500-kHz energy generator were tested, creating 90 lesions in isolated porcine hearts. The RF current was applied between the linear probe and a large patch electrode attached to the back of the specimen. Three parameters, comprising the power of the delivered energy, the pressure of contact between the probe and the specimen, and the duration of energy delivery were changed independently and the size of the resulting lesions was measured. All 90 lesions were transmural, well demarcated and created by a single stationary RF application. Lesion length and width increased with: 1) increasing power, when the other two parameters were maintained at constant levels, 2) increasing contact pressure, when the other two parameters were maintained at constant levels, and 3) increasing duration of energy delivery when the other two parameters were maintained at constant levels. The maximum width of the lesions was 3.7 mm. No overheating of any of the specimens was observed. In conclusion, the new original long linear probe used in this study was effective for creating transmural linear lesions, presenting the possibility of a worthwhile contribution to the maze surgical procedure applied to atrial fibrillation.

Radiofrequency catheter ablation of left ventricular outflow tract tachycardia from the coronary cusp: a new approach to the tachycardia focus.

INTRODUCTION: Idiopathic ventricular tachycardia (VT) originating from the left ventricular outflow tract (LVOT) is rare. Previously reported were two cases of LVOT tachycardia which were treated with radiofrequency (RF) catheter ablation through endocardial aortomitral continuity. We report here a case of a repetitive LVOT tachycardia in which the QRS morphology during VT exhibited an atypical left bundle branch block and inferior axis. Pace mapping revealed that the origin of this VT was very close to the left sinus of Valsalva. Transcoronary cusp RF catheter ablation abolished the VT in this patient and is a new approach for the treatment of this kind of VT. The application of this approach to the other types of VT has yet to be determined.

Radiofrequency catheter ablation of idiopathic right ventricular tachycardia near the His bundle.

There are only a few reports on successful radiofrequency catheter ablation of idiopathic right ventricular tachycardia (VT) originating from other sites than right ventricular outflow tract. We report here a case of VT which exhibited an inferior-axis and a left bundle branch block pattern and originated near the His bundle. Using the temperature-controlled ablation catheter, prudent observation of the fluoroscopy and intracardiac electrograms during pacemapping, we successfully ablated the origin of the VT without any conduction disturbance. However, further study is required to determine the effectiveness of catheter ablation and the long term prognosis for this type of VT.

Radiofrequency catheter ablation of left ventricular outflow tract tachycardia: report of two cases.

Idiopathic ventricular tachycardia (VT) originating from the left ventricular outflow tract (LVOT) is rare. We report two patients whose QRS configuration during VT commonly showed an inferior axis and monophasic R waves in all the precordial leads. The mechanism of these VTs appeared to be triggered activity. From mapping and ablation, the origin of these VTs was determined to be in the most posterior LVOT, corresponding to the aortomitral continuity (left fibrous trigone).