Tadayuki Hiroki

Electrophysiological properties in chronic lone atrial fibrillation.

BackgroundAlthough the electrophysiological mechanisms underlying self-sustaining atrial fibrillation (AF) are unclear, recent studies suggest that one requirement for reentry, slow conduction, is frequently present in patients with AF. However, these observations limited to paroxysmal AF may not necessarily apply to chronic AF. Therefore, electrophysiological properties of the atrium and sinus nodal function in chronic lone AF were evaluated. Methods and ResultsElectrophysiological studies were performed after electrocardioversion in 12 patients with chronic lone AF. Atrial enlargement was absent in the patients with AF. Twelve patients without atrial arrhythmias served as the control group. The patients with AF had a higher incidence of sinus nodal dysfunction, a shorter atrial effective refractory period (215 ± 19 msec versus 238 ± 23 msec, p < 0.02), and a longer P wave duration than control patients (115 ± 16 msec versus 86 ± 16 msec, p < 0.01). The conduction delay zone was significantly greater in patients with AF (60 ± 12 msec) than that in the control patients (8 ± 13 msec, p < 0.01), and the maximal conduction delay was also greater in the study patients than those in the control group, both to the His bundle region (31 ± 12 msec versus 10 ± 15 msec, p < 0.01) and to the coronary sinus (41 + 15 msec versus 15 ± 11 msec, p < 0.01). The fragmented atrial activity zone was wider in the study group (23 ± 25 msec) than in control subjects (1.7 ± 4 msec, p < 0.02). Repetitive atrial firing was observed in four patients with AF but it was not seen in the control group. ConclusionsThese electrophysiological features, which are manifestations of the abnormal atrial electrophysiology, would favor production of atrial reentry in chronic lone AF.

Significance of adventitial inflammation of the coronary artery in patients with unstable angina: results at autopsy.

A quantitative analysis of adventitial inflammation of the coronary artery with intimal lesions is described in 12 patients who suffered coronary death and had had unstable angina (crescendo angina) at rest (group 1). After autopsy in these patients we examined epon-embedded cross sections by light and electron microscopy, paying particular attention to the adventitia, and compared these results with those in six patients who had had angina but died of noncardiac causes (group 2) and those in 22 patients who did not have angina (group 3). Of the 132 segments from group 1 patients, 39 (30%) were narrowed 76% to 100% by atherosclerotic plaque (group 2, 27%; group 3, 1%), and 23 (17%) had occlusive thrombi. Of the 264 sections (two from each segment) from group 1 that were examined, 98 (37%) (group 2, 15%; group 3, 9%) revealed clustered infiltration of inflammatory cells in the adventitia, half of which were associated with vascular nerve involvement. These findings in the adventitia may be related to the vasospastic component of unstable angina.

Plasma fibrinogen levels as an independent indicator of severity of coronary atherosclerosis.

The relationship between plasma fibrinogen levels and the severity of coronary atherosclerosis was examined in 229 patients, aged 25-82 years (162 men and 67 women), undergoing coronary angiography. Severity of coronary atherosclerosis was assessed in terms of the number of vessels with a 75% or greater stenosis and Gensinis severity score. Fibrinogen levels increased progressively with the severity of coronary atherosclerosis, determined by both the number of involved vessels and Gensinis severity score in men, and the relationships were statistically significant. Similar patterns were noted among women, but the trends were not statistically significant. The association was evident even after adjustment for age, hypertension, total cholesterol, cigarette smoking, alcohol intake, high density lipoprotein cholesterol and body mass index. These results provide evidence that in the Japanese also plasma fibrinogen levels can serve as an independent indicator of the progression of coronary atherosclerosis.

Arterial changes after percutaneous transluminal coronary angioplasty: Results at autopsy

Light and electron microscopic examinations were performed on 20 coronary artery sites from nine patients who had undergone percutaneous transluminal coronary angioplasty. Twelve successfully dilated sites without prior thrombosis showed evidence of a tear in the luminal surface (with or without fracture of an atheroma) even at 140 days after angioplasty. The tear split through a relatively undistensible intima in 9 (75%) of the 12 sites. Two successfully dilated sites with prior thrombosis showed an intraintimal tear with a widely lacerated fibrous cap and thin mural thrombus. After dilation, the occluded prior nonthrombosed site showed marked protrusion of a separated plaque. An occluded prior thrombosed site after dilation revealed intraintimal canal-like hematoma. Four sites that occluded after balloon passage revealed a dissecting hematoma in three and plaque disruption in the other.

Low energy synchronous transcatheter cardioversion of atrial flutter/fibrillation in the dog

The feasibility and effectiveness of low energy synchronous transcatheter cardioversion of atrial flutter and fibrillation were examined in dogs with talc-induced pericarditis. A conventional electrode catheter was positioned transvenously in the right atrial appendage. Atrial flutter/fibrillation was induced by using the train pulse method, and the tachyarrhythmia-inducing threshold was determined. The minimal effective cardioversion energy levels were compared in three different cardioversion methods: method A = delivery of shock between the proximal electrode (cathode) and the backplate (anode), method B = delivery between the proximal electrode (cathode) and the distal electrode (anode) and method C = conventional external cardioversion. In both methods A and B, all 149 cardioversion attempts were successful with shocks of less than or equal to 5 J. Shocks of less than or equal to 1 J resulted in successful cardioversion in 57 (70%) of 81 attempts, 50 (74%) of 68 attempts and 5 (12%) of 41 attempts with methods A, B and C, respectively. The mean minimal effective cardioversion energy levels were not significantly different between methods A and B (0.62 +/- 0.67 versus 0.58 +/- 0.71 J). Transcatheter cardioversion decreased the defibrillation threshold 3- to 75-fold (mean 6- to 7-fold) from that of transthoracic cardioversion. The defibrillation threshold was not influenced by the inducibility of atrial flutter/fibrillation. There were no complications of heart block, ventricular fibrillation or pathologic evidence of severe shock-induced atrial injury. Thus, low energy synchronous transcatheter cardioversion of atrial flutter/fibrillation is considered feasible and effective. This technique may also be useful in managing the atrial flutter/fibrillation that can occur during electrophysiologic studies.

Effects of Transcatheter Cardioversion on Chronic Lone Atrial Fibrillation

The effectiveness and safety of internal transcatheter Cardioversion on chronic lone atrial fibrillation were examined in ten patients resistant to external electrical (400 joules) and pharmacological Cardioversion. Transcatheter Cardioversion was performed by pulling back the atrioventricular junction catheter just inferior to the site of the His‐bundle recording and delivering the shock between a proximal electrode (cathode) and backplate (anode). Transcatheter Cardioversion restored sinus rhythm in all of the ten patients. The only complication observed was transient atrioventricular block after the shock and this was treated by temporary pacing. However, atrial fibrillation recurred in five patients at 30, 27, 52, 1, and 6 days, respectively. A second attempt at transcatheter Cardioversion was performed in those patients and was successful in three patients. During a follow‐up period ranging from 12 to 22 months, eight patients continued in sinus rhythm. Thus, transcatheter Cardioversion is considered effective and safe in selected patients with chronic lone atrial fibrillation in whom external Cardioversion was unsuccessful.

Long-term effects of LDL apheresis on carotid arterial atherosclerosis in familial hypercholesterolaemic patients

Objectives. To assess the long‐term effect of LDL apheresis on carotid arterial atherosclerosis in severe familial hypercholesterolaemic (FH) patients.

Acute Pulmonary Thromboembolism Treated Successfully by Balloon Angioplasty—A Case Report

Acute pulmonary thromboembolism frequently occurs in patients on pro tracted bed rest and by itself can cause acute right ventricular failure. The authors report findings in a patient with this disorder treated successfully by balloon angioplasty.

Effects of an Angiotensin II Antagonist on Reperfusion Arrhythmias in Dogs

Losartan, an angiotensin II receptor antagonist with no bradykinin potentiating property, provides the opportunity to study the consequences of blocking angiotensin II. The objective of this study was to evaluate the antiarrhythmic responses of reperfusion arrhythmia to hsartan in dogs. The effects of losartan on ventricular tachyarrhythmias induced during occlusion and reperfusion of the left anterior descending coronary artery were investigated in 30 dogs. The animals were randomized to receive either losartan (n = 15) or saline (n = 15). The VF inducing threshold was measured before occlusion and after reperfusion. Losartan (50 μg/kg per min) or saline was intravenously administered 5 minutes before occlusion and continued throughout the entire study period. The incidence of ventricular tachyarrhythmias during reperfusion was lower in the losartan group than in the control group (4/15 vs 6/15). There was no significant change in VF inducing threshold between the period before occlusion and during reperfusion in the losartan group (10.9 ± 5.7 vs 11.1 ± 5.7mA, P = NS), whereas there was a significant decrease in the control group (15.5 ± 4.4 vs 7.7 ± 3.9 mA, P < 0.01). Blockade of the angiotensin II receptor has beneficial effects on reperfusion arrhythmias.

Transesophageal low-energy synchronous cardioversion of atrial flutter/fibrillation in the dog.

The purpose of this study was to determine the feasibility and efficacy of terminating atrial flutter/fibrillation using low-energy synchronous shocks delivered through a transesophageal catheter in dogs with talc-induced pericarditis. Atrial flutter/fibrillation was induced by employing the pulse train method. The minimum effective cardioversion energy level was compared for three different methods--method A, delivery between a distal esophageal electrode and a proximal esophageal electrode; method B, delivery of shocks through a distal esophageal electrode and a plate placed on the chest; method C, transthoracic cardioversion. The minimum effective cardioversion energy level did not differ significantly between methods A and B (1.30 +/- 0.46 joules versus 1.29 +/- 0.35 joules). Transesophageal cardioversion decreased the defibrillation threshold three- to fourfold from that of conventional transthoracic cardioversion. There were no complications of heart block, ventricular fibrillation, or any pathologic evidence of esophageal injury. Thus transesophageal low-energy synchronous cardioversion is considered a feasible and effective method for the treatment of atrial flutter/fibrillation.