Takeshi Tadera

Demonstration of the Reentrant Circuit of Verapamil-Sensitive Idiopathic Left Ventricular Tachycardia: Direct Evidence for Macroreentry as the Underlying Mechanism

Reentrant Circuit of Idiopathic LV Tachycardia. The exact reentrant circuit of verapamilsensitive idiopathic left ventricular tachycardia (ILVT) remains unclear. This case report demonstrates the reentrant circuit of ILVT. A 20‐pole electrode catheter was placed along the left posterior fascicle during electrophysiologic study. ILVT was reproducibly induced by programmed ventricular stimulation. During the tachycardia, sequential diastolic potentials bridging the entire diastolic period were observed in the recordings from the electrodes positioned from left ventricular mid‐septum to inferoapical septum. The slow conduction zone appeared to be composed of a false tendon in this patient. Entrainment of the ILVT from the right ventricular outflow tract at a different pacing cycle length revealed that a dominant conduction delay occurred at the proximal site of the slow conduction zone. Entrainment studies from several sites on the left ventricular septum confirmed that these sites where sequential electrical activity was recorded were included within the reentrant circuit. However, the left posterior fascicle itself seemed to be a bystander. This report provides the direct evidence of macroreentry as the underlying mechanism of this ILVT, adjacent to the left posterior fascicle.

Exit block of focal repetitive activity in the superior vena cava masquerading as a high right atrial tachycardia.

AT Originating from the SVC. An unusual case of atrial tachycardia (AT) originating from the superior vena cava (SVC) is reported. A 34‐year‐old man without structural heart disease underwent catheter ablation for drug‐resistant AT. During the tachycardia, low‐amplitude spiky electrograms with a cycle length of 120 to 175 msec were recorded in the SVC and exhibited 2:1 exit block to the atria, masquerading as the atrial activation observed with high right AT. These spiky electrograms also were observed during sinus rhythm, but they appeared immediately after the local atrial electrograms. The spikes were traced to a point 3 cm above the junction of the right atrium. Radiofrequency ablation at the site of the earliest appearance of the spike in the SVC successfully eliminated the tachycardia. During the following 15 months, no clinically significant atrial arrhythmias, including atrial fibrillation, occurred. This report indicates that careful mapping, including inside the SVC, will be a requisite in patients with high right atrial tachyarrhythmias.

Utility of rapid D-dimer measurement for screening of acute cardiovascular disease in the emergency setting

BACKGROUND Rapid and accurate methods for screening are necessary for the diagnosis of acute cardiovascular diseases (ACVD), including acute coronary syndrome (ACS), pulmonary thromboembolism, and acute aortic dissection. In this study, the utility of rapid D-dimer measurement for the screening of ACVD was evaluated. METHODS AND RESULTS Consecutive 279 emergent patients in whom ACVD was suspected or not ruled out were enrolled. The median D-dimer concentration of ACVD group (1.10 μg/ml) was significantly higher than that in the non-ACVD group (0.69 μg/ml, p<0.05). Sensitivity, specificity, positive predictive value, and negative predictive value of D-dimer (with cut-off level of 0.75 μg/ml) for the discrimination of ACVD from non-ACVD was 75%, 55%, 38%, and 85%, respectively. In ACVD group, the level of D-dimer in the large vessel disease subgroup was significantly higher than that in the ACS subgroup (6.99 μg/ml and 0.89 μg/ml, respectively; p<0.05). The well-balanced cut-off point for discriminating the two subgroups was D-dimer level of 5.0 μg/ml. D-dimer (with cut-off level of 0.75 μg/ml) showed significantly higher positive test rate for the detection of ACS in very early phase (within 2 h from the onset) compared with troponin T (p<0.05). CONCLUSIONS Rapid measurement of D-dimer is useful for the screening of ACVD in the emergency setting.

A Case of Slowly Progressive Purulent Pericarditis in Elderly Healthy Woman

A 67-year-old woman was admitted with dyspnea. The cheat X-ray showed marked cardiomegaly and the echocardiography revealed diffuse massive pericardial effusion but no finding of vegetation on valves. Clinical sign of cardiac tamponade was not observed. Values of white blood cell and C-reactive protein were 23,900/μL and 16.2 mg/dL, respectively. Immediately, pericardiocentesis was performed. Pericardial effusion was yellowish purulent exudate and Streptococcus pneumoniae was detected in culture. The early pericardial drainage and the effective doses of intravenous antibiotics and γ-globulin were successful for the treatment of this bacterial pericarditis, and no more surgical procedure was needed. Neither recurrence of inflammation nor constrictive pericarditis was developed after discontinuation of antibiotics during the follow-up period for over three years at the outpatient clinic. In this case, an infection route was unknown since pneumonia, empyema, or other focus of infection was not found. Although she had an upper respiratory infection one year prior to this pericarditis, their association was unclear. She was previously healthy and was not a compromised host. This case is thought to be rare bacterial pericarditis with slow progression in the recent antibiotic era.

Pseudotermination of atrioventricular nodal reentrant tachycardia related to isorhythmic atrioventricular dissociation.

Unusual manifestations of the mode of termination were observed in a patient with atrioventricular nodal reentrant tachycardia (AVNRT). After administration of verapamil during AVNRT, isorhythmic atrioventricular dissociation occurred without termination of the tachycardia. The sinus rate was slightly faster than that of the AVNRT, leading to the P wave preceding the QRS complex with a normal PR interval (e.g., pseudotermination). This phenomenon emphasizes the importance of continuous monitoring during an attempt to terminate AVNRT. (PACE 2003; 26:2338–2339)