Motonobu Hayano

The prevalence, incidence and prognostic value of the Brugada-type electrocardiogram: a population-based study of four decades.

OBJECTIVESnWe sought to demonstrate the prevalence, incidence and prognostic value of the Brugada-type electrocardiogram (ECG) in a general population.nnnBACKGROUNDnThe Brugada syndrome is characterized by evidence of right bundle branch block and ST segment elevation in the right precordial leads, as well as sudden death caused by ventricular fibrillation. However, the natural history of the Brugada-type ECG remains unclear.nnnMETHODSnWe investigated 4,788 subjects (1,956 men and 2,832 women) who were <50 years old in 1958 and had undergone biennial health examinations, including electrocardiography, through 1999. The Brugada-type ECG was defined as a terminal r wave in lead V(1) and ST segment elevation > or =0.1 mV in leads V(1) and V(2). Unexpected death was defined as sudden death or unexplained accidental death.nnnRESULTSnThere were a total of 32 Brugada-type ECG cases; the prevalence and incidence were 146.2 in 100,000 persons and 14.2 persons per 100,000 person-years, respectively. The incidence was nine times higher among men than women, and the average age at presentation was 45 +/- 10.5 years. The Brugada-type ECG appeared intermittently in most cases and was found in 26% of subjects who died unexpectedly. Cox survival analysis revealed that mortality from unexpected death was significantly higher in subjects with a Brugada-type ECG than in control subjects (p < 0.01). Unexpected deaths were more frequent among subjects with the Brugada-type ECG who had a history of syncope (p < 0.05).nnnCONCLUSIONSnThe Brugada-type ECG is not a very rare condition in the adult Japanese population. Subjects with a Brugada-type ECG have an increased risk of unexpected death.

Preserving Normal Ventricular Activation Versus Atrioventricular Delay Optimization During Pacing: The Role of Intrinsic Atrioventricular Conduction and Pacing Rate

The purpose of the study was to compare the effects of DDD pacing with optimal AV delay and AAI pacing on the systolic and diastolic performance at rest in patients with prolonged intrinsic AV conduction (first‐degree AV block). We studied 17 patients (8 men, aged 69 ± 9 years) with dual chamber pacemakers implanted for sick sinus syndrome in 15 patients and paroxysmal high degree AV block in 2 patients. Aortic flow and mitral flow were evaluated using Doppler echocardiography. Study protocol included the determination of the optimal A V delay in the DDD mode and comparison between AAI and DDD with optimal A V delay for pacing rate 70/min and 90/min. Stimulus‐R interval during AAI (AHI) was 282 ± 68 ms for rate 70/min and 330 ± 98 ms for rate 90/min (P < 0.01). The optimal A V delay was 159 ± 22 ms, A V delay optimization resulted in an increase of an aortic flow time velocity integral (AFTVI) of 16%± 9%. At rate 70/min the patients with ARI ≤ 270 ms had higher AFTVI in AAI than in DDD (0.214 ± 0.05 m vs 0.196 ± 0.05 m, P < 0.01), while the patients with ARI > 270 ms demonstrated greater AFTVI under DDD compared to AAI(0.192 ± 0.03 m vs 0.166 ± 0.02 m, P < 0.01). At rate 90/min AFTVI was higher during DDD than AAI (0.183 ± 0.03 m vs 0.162 ± 0.03 m, P < 0.01). Mitral flow time velocity integral (MFTVI) at rate 70/min was higher in DDD than in AAI (0.189 ± 0.05 m vs 0.173 ± 0.05 mP < 0.01), while at rate 90/min the difference was not significant in favor of DDD (0.149 ± 0.05 m vs 0.158 ± 0.04 m). The results suggest that in patients with first‐degree AV block the relative impact of DDD and AAI pacing modes on the systolic performance depends on the intrinsic AV conduction time and on pacing rate.

Electrophysiological abnormalities of the atrial muscle in patients with paroxysmal atrial fibrillation associated with hyperthyroidism.

objective Atrial fibrillation (AF) is common in patients with hyperthyroidism. Although the choice of an antiarrhythmic agent should be based on its electrophysiological effects and the electrophysiological properties of the arrhythmia in question, the atrial electrophysiological features of AF associated with hyperthyroidism are unknown. The purposes of this study are to clarify the atrial electrophysiological abnormalities of AF with hyperthyroidism, and to propose effective therapies for AF in patients with hyperthyroidism.

Electrophysiological effects of MS-551 in humans: a class III antiarrhythmic agent.

To investigate the clinical effects of MS‐551, a Class III antiarrhythmic agent, 11 patients underwent electrophysiological study. MS‐551 was given intravenously as an initial dose of 0.2 or 0.3 mg/kg for 5 minutes followed by the continuous infusion at 0.2 or 0.3 mg/kg for 30 minutes, respectively, in all patients. The rate corrected QT interval increased significantly from 3 minutes after the beginning of MS‐551 infusion. The sinus heart rate decreased significantly by 8% at 10 minutes after the drug administration (P ± 0.025). Mean PR and QRS intervals, and blood pressure were not significantly affected by the drug. Mean PA, AH, and HV intervals during sinus rhythm were also not affected. The effective refractory periods (ERPs) of the atrium and ventricle were significantly prolonged by 13% from 202 ± 24 ms to 231 ± 26 ms (P ± 0.0005), and by 7% from 238 ± 11 ms to 257 ± 13 ms (P ± 0.002), respectively, by MS‐551. The ERP of the atrioventricular node and sinoatrial nodal recovery time were not changed significantly by the drug. This is a report of the effects of MS‐551 in humans. This agent could be useful for treatment of tachyarrhythmias by prolongation of ERPs of the atrium and ventricle without significant variations of blood pressure and intracardiac conduction times. It is noteworthy that MS‐551 slightly but significantly decreased heart rate.

Abnormalities of Electrocardiographic P Wave Morphology and Their Relation to Electrophysiological Parameters of the Atrium in Patients with Sick Sinus Syndrome

We examined the incidence, of long P wave duration in lead II and increased P terminal force in lead V1(PTFV1), and their relationship to electrophysiological findings of atrial muscle in 34 patients with sick sinus syndrome (SSS). Patients were divided into three groups: Group I, consisting of 20 patients with various cardiac arrhythmias other than SSS and paroxysmal atrial fibrillation (PAF) who served as controls; Group II, consisting of 18 patients with SSS but without PAF; and Group III consisted of 16 patients with SSS and PAF. P wave duration was significantly longer in Group III (122 ± 11ms, mean ± SD, P < 0.0001) and Group II (111 ± 15 ms, P < 0.002) than in Group I (98 ± 10 ms). PTFV1 was greater in Group III (0.052 ± 0.025 ms) than in Group I (0.028 ± 0.011 ms, P < 0.05). P wave duration and PTFV1 had significantly and/or borderline correlations with longest duration of right atrial electrograms (r = 0.84, P < 0.0001 and 0.47, P < 0.02, respectively), maximal number of fragmented deflections of atrial electrograms (r = 0.69, P < 0.0001 and r = 0.51, P < 0.02, respectively), repetitive atrial firing zone (RAFZ) (r = 0.81, P < 0.0001 and 0.48, P < 0.05, respectively) and fragmented atrial activity zone (FAAZ)(r ‐ 0.53, P < 0.01 and r = 0.45, P = 0.06, respectively). We concluded that long P wave duration and increased PTFV1 are electrocardiographic indicators for coexistence of electrophysiological abnormalities in the atria in SSS without recognizable heart disease.

Electrophysiological Properties of the Left Atrium Evaluated by Coronary Sinus Pacing in Patients with Atrial Fibrillation

Repetitive atrial firing (RAF), marked fragmentation of atrial activity (FAA), and interatrial conduction delay (CD) have been shown to be electrophysiological features of the atrium in patients with atrial fibrillation (AF). Moreover, it has been observed that atrial extrastimuli are more likely to induce AF when delivered from the right atrial appendage (RAA) than from the distal coronary sinus (CSd). We examined the electrophysiological properties of the atrial muscle by CS and RAA stimulation in patients with paroxysmal AF. Patients were divided into two groups: group I, consisting of 18 patients with clinical paroxysmal AF; and group II, consisting of 22 patients with various cardiac arrhythmias in which the substrate does not exist in the atrium. In group I, the following values of electrophysiological parameters of the atrium indicated that AF was more likely to be induced during RAA pacing than CSd pacing: atrial effective refractory period (RAA vs CSd: 201 ± 28 ms vs 240 ± 35 ms, P < 0.001), RAF zone (16 ± 25 ms vs 0 ± 0 ms, P < 0.03), FAA zone (38 ± 37 ms vs 5 ± 19 ms, P < 0.01), maximum interatrial conduction time (144 ± 19 ms vs 93 ± 19 ms, P < 0.0001) and CD zone (53 ± 21 ms vs 9 ± 18 ms, P < 0.0001). The values of the electrophysiological parameters of the atrium evaluated by CSd pacing in group I patients were not significantly different from those in group II patients. In conclusion, when coronary sinus stimulation is performed, electrophysiological properties of the atrium in patients with AF show a significant decrease in atrial vulnerability compared to stimulation from RAA and also show similar values to those in patients without AF. It might be suggested that the left posterior or posterolateral atrium is electrophysiologically stable even in patients with paroxysmal AF.

Evidence of quadruple anterograde atrioventricular nodal pathways in a patient with atrioventricular node reentry.

Functional longitudinal dissociation of the atrioventricular (AV) node exhibiting two discrete discontinuities in AV nodal conduction curves suggestive of triple AV nodal pathways has been described. The authors report here unusual electrophysiologic properties of the AV node in a patient with documented episodes of paroxysmal supraventricular tachycardia. Programmed atrial extrastimuli introduced at A1-A2 coupling intervals of 390 ms with a driven cycle length of 500 ms produced a sudden marked increase of 75 ms at the A2-H2 intervals suggesting failure of the fast pathway with conduction proceeding through a slower pathway with a shorter refractory period. With further decreasing coupling intervals, a second sudden jump of 70 ms and a third one of 150 ms occurred at A1-A2 coupling intervals of 330 and 290 ms, respectively. Beyond the first sudden jump, atrial echoes occurred when sufficiently slow pathway delay permitted recovery of the fast pathway for retrograde conduction. The atrial echo zone was 170 ms. These electrophysiologic demonstrations of reentry within the AV node in a patient with clinically documented supraventricular tachycardia and the existence of four ranges of AH conduction times and refractory periods strongly suggest the presence of quadruple anterograde AV nodal pathways and a variety of potential loops available for the development of sustained AV nodal reentrant tachycardia.

Congenital defect of the left pericardium with sick sinus syndrome

years. 5 Aortic stenosis is rare, bu t approximately 50% of patients with quadricuspid aortic valve have aortic regurgitation. 5 Two-dimensional transthoracic echocardiography has become the diagnostic test of choice, because the four cusps and their relative sizes can easily be seen. 4, 5 In addition, Doppler echocardiography is an excellent modality for assessing the degree of aortic regurgitat ion and its progression. 4 However, because of technical factors such as suboptimal echocardiographic windows or extensive aortic calcification, transthoracic echocardiography may occasionally be limited in visualizing the aortic valve. Transesophageal echocardiography overcomes many of the imaging l imitat ions of transthoracic echocardiography and can clearly delineate the aortic valve morphologic characteristics. 6 In our case the exact cause of the severe aortic regurgitat ion was not seen on transthoracic echocardiography. Transesophageal echocardiography was performed to assess the mitral valve, and the quadricuspid aortic valve was discovered incidentally. To the best of our knowledge this is the first case of quadricuspid aortic valve diagnosed exclusively by transesophageal echocardiography in the English language literature. In conclusion, a quadricuspid aortic valve is a rare congenital abnormali ty tha t usual ly can be diagnosed by transthoracic twodimensional echocardiography. A high degree of suspicion is required to make the diagnosis, because this abnormality can easily be overlooked. On occasion the transthoracic echocardiogram cannot show the quadricuspid na tu re of the aortic valve, and transesophageal echocardiography mus t be performed. REFERENCES

Thromboembolic Complication in Atrial Fibrillation in a Long-Term FolIow-Up

The incidence of thromboembolic complications among 288 patients with atrial fibrillation (AF) who were followed up during an average period of 7.2 years was examined retrospectively. The annual incidence of thromboembolic complications was 1.6% in total, 1.7% in valvular heart disease (n=128), and 2.1% in non-valvular heart disease (n=117). No thromboembolism occurred in lone AF (n=43), defined as the complete absence of any underlying disease. The type of AF before embolic attack was chronic in 26 cases and paroxysmal in 6 cases. The cardiac rhythm at the time of the embolic attack was AF, except in 2 cases in which ECG was not recorded. In all patients with thromboembolic complications who were receiving antithrombotic therapy during the follow-up, the anticoagulant effect just before the embolic attack was found to be insufficient. Major bleeding was not observed in the patients receiving antithrombotic therapy. Thromboembolism in AF in long-term follow-up tends to occur more frequently in patients with underlying heart disease and in those with chronic AF compared rather than paroxysmal AF; it rarely occurs in lone AF. We should not hesitate to administer sufficient anticoagulant therapy in AF patients who are at high risk of developing thromboembolic complications. (Jpn Circ J 1998; 62: 255 - 260)

Simultaneous atrial and ventricular pacing to facilitate mapping of concealed left-sided accessory pathways.

NAKAO, K., et al.: Simultaneous Atrial and Ventricular Pacing to Facilitate Mapping of Concealed Left‐Sided Accessory Pathways. Several local electrogram characteristics have been proposed as criteria to predict successful ablation. However, poor specificity due to obscuration of the retrograde atrial electrogram by the ventricular electrogram is problematic. The aim of this study was to analyze local electrograms obtained by simultaneous pacing to identify quantitative criteria that may predict successful ablation sites for concealed left free‐wall accessory pathways. Twenty‐four local electrograms from 10 successful and 14 unsuccessful ablation sites in ten patients were analyzed. Retrograde atrial electrograms were confirmed by the simultaneous pacing method. The intervals between the retrograde atrial electrogram of the coronary sinus and the ablation site, the initiation of the ventricular electrogram and the retrograde atrial electrogram, and the stimulus and retrograde atrial electrogram were analyzed. All retrograde atrial electrograms could be confirmed clearly by the simultaneous pacing method. The interval between the retrograde atrial electrogram of the coronary sinus and that of the ablation site was shorter at successful sites than at unsuccessful sites (‐7.0 ± 9.2 ms vs 5.7 ± 2.7 ms; 95% confidence interval, ‐18 to ‐7; P < 0.0001). An interval of ≤ 0 ms resulted in 100% sensitivity and 92.7% specificity for success. The other two interval measurements at successful sites did not differ significantly from those at unsuccessful sites. The authors propose an interval of ≤ 0 ms between the retrograde atrial electrogram of the coronary sinus and that of the ablation site confirmed by the simultaneous pacing method as a quantitative criterion to identify the successful ablation site for concealed left free‐wall accessory pathways. Application of this criterion may reduce the number of unnecessary ablations.