Mid-Diastolic Potential is Related to the Reentrant Circuit in a Patient with Verapamil-Sensitive Idiopathic Left Ventricular Tachycardia

Mid-Diastolic Potential in Idiopathic VT. We report a case of verapamil-sensitive idiopathic ventricular tachycardia in which a mid-diastolic potential (MDP) 45 msec preceding the Purkinje potential ( P potential) was recorded. Pacing during the tachycardia caused concealed entrainment, and the stimulus–QRS interval was equal to the P potential–QRS interval. The interval between the last pacing stimulus and the next P potential (postpacing interval) was longer than the ventricular tachycardia cycle length, but the MDP was orthodromically activated. These findings suggest that the MDP was on the reentrant circuit and the P potential was not on the reentrant circuit, but a bystander.     

Radiofrequency Catheter Ablation of Concealed Atrioventricular Accessory Pathways Using a "Simultaneous Pacing Method"

The retrograde atrial potential at a successful ablation site is usually obscured by the wide and large ventricular potential during atrioventricular reentrant tachycardia or ventricular pacing, which makes it difficult to determine the appropriate ablation site for concealed accessory pathway. A pacing maneuver named the “simultaneous pacing method” is proposed herein to differentiate the retrograde atrial potential from the ventricular potential for a successful ablation of the concealed accessory pathway. Catheter ablation was performed in 12 patients with a single left free-wall concealed accessory pathway. The atrial insertion site was determined by the simultaneous pacing method in six patients (group I) and by ventricular pacing in six patients (group II), In the simultaneous pacing method, electrograms recorded during ventricular pacing in the earliest retrograde atrial activation site are a fusion of the ventricular potential and the following retrograde atrial potential. When atrial and ventricular pacings are performed simultaneously (simultaneous pacing), the end portion of the electrograms recorded at the same site is solely the ventricular component, because atrial is activated earlier. The atrial potential can be confirmed during ventricular pacing in comparison with the electrograms during the “simultaneous pacing.” Radiofrequency catheter ablation was successful in eliminating conduction through the accessory pathway in all 12 patients. The radiofrequency applications in group I were significantly fewer than those in group II (1.7 ± 1.0 in group I, 5.3 ± 3.2 in group II, P < 0.05). The total procedure time in group I was significantly shorter than in group II (57.8± 15.7 vs 106.7 ± 41.6 mins in group II. respectively, P < 0.05). The fluoroscopy time in group I was significantly shorter than in group II (54.0 ± 7.9 vs 81.3± 26.3 mins, respectively, P < O.05). We were able to determine the atrial insertion site of accessory pathways by the simultaneous pacing method. The simultaneous pacing method was useful in eliminating concealed left free-wall accessory pathways.     

Disappearance of the Brugada-Type Electrocardiogram After Surgical Castration:

We describe two cases of asymptomatic Brugada syndrome that displayed a persistent ECG manifestation, but in which the typical ECG pattern disappeared following surgical castration for prostate cancer. These facts suggest a possible association between manifestation of the Brugada-type ECG pattern and testosterone. (PACE 2003; 26[Pt. I]:1551–1553)     

AP-811, a novel ANP-C receptor selective agonist

AP-811 is a derivative of the Phe8-Ile15 region of atrial natriuretic peptide (ANP) and is one of the smallest linear ligands for ANP receptors. The binding and agonist activities of AP-811 have been compared with those of other ANP analogs for the ANP-A and ANP-C receptors. AP–811 binds with a high binding affinity to and is a strong agonist for the ANP-C receptor, indicating that the binding and agonist sites for this receptor are the same or near each other in the ANP sequence. In contrast, AP-811 showed no agonistic effect for the ANP-A receptor, although it could bind to this receptor. Comparing the biological activities of AP-811 with those of other ANP analogs, we propose that the binding and agonist sites for the ANP-A receptor may consist of separate regions of ANP. In conclusion, AP-811 is the smallest C-receptor-selective agonist.     

Possible Involvement of Cerebral Hypoperfusion as a Trigger of Neurally-Mediated Vasovagal Syncope

It is well known that some patients with neurally mediated syncope have a feeling of aura before the onset of syncope. A case is reported in which cerebral dysfunction recorded by EEG was present before the onset of a vasovagal reaction. The vasovagal reaction, bradycardia and/or asystole, was preceded by abnormal EEG findings when the patient complained of feeling a headache, photophobia, and nausea. These findings suggest that cerebral hypoperfusion, such as with cerebral vasospasms, before the onset of bradycardia might be involved in the mechanism of neurally mediated syncope in patients with an aura.     

Increased Dispersion of Repolarization Time Determined by Monophasic Action Potentials in Two Patients with Familial Idiopathic Ventricular Fibrillation

Increased Dispersion of RT in Familial Idiopathic VF. Introduction: The role of increased dispersion of repolarization in the genesis of torsades de pointes in patients with long QT syndrome has been clarified, but its role in the genesis of idiopathic ventricular fibrillation (VF) is not yet known. To investigate the pathogenesis of VF, we recorded monophasic action potentials (MAPs) from two siblings (48- and 36-year-old males) with familial idiopathic VF. Methods and Results: The elder brother (patient I) showed a late r’ wave in lead V¹ and ST segment elevation in leads V¹ through V³. The younger brother (patient 2) had late r’ waves and ST segment elevation in leads II, III, and aVF, and the configurations were very similar to those of patient I. MAPs were recorded from several sites in the right ventricular (RV) and left ventricular (LV) endocardium during constant right atrial pacing. The repolarization time (RT) was defined as the sum of the activation time (AT) and action potential duration (APD) at 90% repolarization. In patient 1, marked prolongation of the AT (140 msec) and the RT (380 msec) was recorded in the RV septum of the outflow tract, and the RT dispersion was markedly increased (125 msec). In contrast, patient 2 showed prolongation of the AT (80 msec) and RT (310 msec), and fractionated electrograms in the RV floor of the inflow tract. The RT dispersion was also increased (80 msec). VF and nonsustained polymorphic ventricular tachycardia were induced by double premature stimulation in patients 1 and 2, respectively. Chronic amiodarone therapy decreased the RT dispersion and suppressed the induction of ventricular tachyarrhythmias in patient 2, although late r’ waves and slight ST segment elevation were unmasked in leads V₁, and V₂. Conclusion: Our data suggest that the increased dispersion of the RT, which was due mainly to a localized conduction delay in the RV, created an arrhythmogenic substrate in the two patients with familial idiopathic VF.     

Dynamic Changes of 12-Lead Electrocardiograms in a Patient with Brugada Syndrome

Dynamic ECG Changes in Brugada Syndrome. We present a patient with Brugada syndrome in whom 12-lead ECXis were recorded just before and after an episode of ventricular fibrillation (VF). A progressive elevation of both the RS-T segment and J waves just preceding and following the VF, and a close relationship between the amplitude of the RS-T segment and the preceding R-R intervals during atrial fibrillation, were documented. These findings support the hypothesis that RS-T elevation and a subsequent VF are related to a transient outward current-mediated spike-and-dome morphology of the epicardial action potential.     

Acute Effects of Different Atrial Pacing Sites in Patients with Atrial Fibrillation: Comparison of Single Site and Biatrial Pacing

It has been reported that a trial single site or biatrial pacing can suppress the occurrence of AF. However, its mechanism remains unclear. The study population included 32 patients with AF (n = 20: AF group), or without paroxysmal AF (n = 12: control group). The mechanism and efficacy of atrial pacing were investigated by electrophysiological studies to determine which was more effective for suppressing AF induction; single site pacing of the right atrial appendage (RAA) or distal coronary sinus (CS-d), or biatrial (simultaneous BAA and CS-d) pacing. In the AF group, AF inducibility was significantly higher with BAA extrastimulus during RAA (12/20; P < 0.0001) or biatrial paced drive (7/20; P < 0.01) than during CS-d paced drive (0/20). In the control group, AF was not induced at any site paced. In the AF group, the conduction delay and other parameters of atrial vulnerability significantly improved during CS-d paced drive. The atrial recovery time (ART) at RAA and CS-d was measured during each basic pacing mode. ART was defined as the sum of the activation time and refractory period, and the difference between ARTs at RAA and CS-d was calculated as the ART difference (ARTD). The ARTD was significantly longer during BAA pacing in the AF group than in control group (155.0 +/- 32.8 vs 128.8 +/- 32.9 ms, P < 0.05). In the AFgroup, ARTDs during biatrial (52.0 +/- 24.2 ms) and CS-d pacing (51.7 +/- 26.0 ms) were significantly shorter than ARTD during RAA pacing. The CS-d paced drive was more effective for suppressing AF induction than biatrial or RAA paced drive by alleviating conduction delay. CS-d and biatrial pacing significantly reduced ARTD compared with RAA pacing.     

Primary gastric lymphoma with arterial bleeding

We experienced a case of primary gastric lymphoma with arterial bleeding. The case was an 88‐year‐old‐man who was admitted to our hospital with hematemesis. Gastroduodenal endoscopy revealed a gastric ulcerating tumor with arterial bleeding in the posterior wall of the angular gastric region, and a distal subtotal gastrectomy with lymph node dissection was performed. The resected tumor measured 7.0 × 3.0 cm in size with a blood vessel visible in the bottom of the ulcer. Pathologic examination confirmed a diagnosis of B‐cell malignant lymphoma of the diffuse large cell type. Metastasis was detected in nos 3 and 5 lymph nodes. According to the Ann Arbor and Naquvi classifications, the lymphoma was stage IIE and II, respectively. One year and 10 months after the operation, a computed tomography scan revealed a few swollen lymph nodes around the abdominal aorta. Recurrence of lymphoma was confirmed and chemotherapy comprising cyclophosphamide, doxorubin, vincristine and predonisolone was given at half the ordinary adult dose.     

Susceptibility genes for schizophrenia

Abstract  It is well known that genetic factors contribute to the susceptibility for schizophrenia. Recent advances in the molecular genetics of schizophrenia strongly suggest several susceptibility genes (e.g. dysbindin, neuregulin-1, DISC1, COMT, G72, RGS4 and Akt1). We discuss the evidence and biology of these genes. As glutamate transmission is especially implicated in these genes, neurobiological basis of schizophrenia might be elucidated by investigation of functional interactions between susceptibility genes for schizophrenia and the glutamatergic system.