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Biomedical subjects

O Fujimura

Publications and source records attributed to O Fujimura.

At least 37 records · Page 2Linked to original sources
PubMed1990

Skeletonization of the atrioventricular node for AV node reentrant tachycardia: experience with 32 patients.

We describe our experience with operative therapy for atrioventricular (AV) node tachycardia using an anatomically guided procedure. The operative rationale was to dissect the AV node from most of its atrial inputs (AV node "skeletonization") with the intent of altering the perinodal substrate and preventing reentry. The anteroseptal and posteroseptal regions were initially approached epicardially to facilitate identification of anatomical structures. Under normothermic cardiopulmonary bypass, the right atrial septum was mobilized and the intermediate AV node was exposed anterior to the tendon of Todaro. Atrioventricular node conduction was monitored electrocardiographically throughout the procedure. Ablation of concomitant accessory pathways was done prior to AV node skeletonization. Thirty-two patients aged 9 to 67 years (mean age, 30 years) underwent operation. Five patients had concomitant accessory pathways in addition to AV node reentry. At electrophysiological study before discharge, no patient had AV block although anterograde and retrograde Wenckebach cycle lengths were significantly prolonged. Six patients had retrograde AV block. Twenty-nine patients are free from arrhythmia and require no antiarrhythmic medication after a follow-up of 1 month to 45 months (mean follow-up, 17 months). Three patients had recurrence of tachycardia ten days, 2 months, and 7 months postoperatively. All patients subsequently had a successful reoperation.

Adolescent↗
PubMed1990

Mode of onset of atrial fibrillation in the Wolff-Parkinson-White syndrome: how important is the accessory pathway?

The mode of onset of 103 episodes of atrial fibrillation lasting greater than or equal to 30 s was studied in 79 patients with the Wolff-Parkinson-White syndrome during electrophysiologic study. No patient had organic heart disease, and 31 had clinical atrial fibrillation before study. These 79 patients were then compared with a control group of 53 patients with Wolff-Parkinson-White syndrome in whom atrial fibrillation could not be induced. Ninety-five of the 103 episodes were technically suitable for analysis. Atrial fibrillation invariably began with rapid atrial tachycardia that became progressively disorganized within 10 to 20 cycles. It was initiated during right atrial stimulation (n = 52), right ventricular stimulation (n = 8), reciprocating tachycardia (n = 33) and spontaneously (n = 2). Most episodes started at a high right atrial site regardless of accessory pathway location, with only 19% of episodes starting at the electrode closest to the accessory pathway. During reciprocating tachycardia (n = 33), either atrial (n = 8) or ventricular (n = 5) extrastimuli initiated atrial fibrillation. Atrial fibrillation started at the accessory pathway site in 6 of 20 episodes occurring spontaneously during reciprocating tachycardia. Patients with atrial fibrillation had a longer PA interval (54 +/- 14 versus 42 +/- 12 ms, p less than 0.0001), shorter atrial functional refractory period (226 +/- 38 versus 240 +/- 30 ms, p = 0.049) and shorter anterograde effective refractory period of the accessory pathway (279 +/- 26 versus 304 +/- 75 ms, p = 0.03). Clinical reciprocating tachycardia was documented with equal frequency in both the atrial fibrillation and control groups (59.5% versus 52.9%, p = 0.58).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Termination of acute atrial fibrillation in the Wolff-Parkinson-White syndrome by procainamide and propafenone: importance of atrial fibrillatory cycle length.

The effects of intravenous procainamide (n = 30) or propafenone (n = 25) were evaluated in 55 patients with acute atrial fibrillation and the Wolff-Parkinson-White syndrome. All patients received either procainamide (12 to 15 mg/kg body weight) or propafenone (1 to 2 mg/kg) during sustained (greater than 10 min) atrial fibrillation or after termination of nonsustained atrial fibrillation. Termination of atrial fibrillation was attributed to a drug if it occurred less than or equal to 15 min after infusion. Measurements included mean cycle length of fibrillatory electrograms (mean AA interval) as measured at the high right atrium and shortest RR interval between pre-excited cycles during atrial fibrillation. Atrial fibrillation terminated more frequently after procainamide administration (65%) than after propafenone (46%), although this difference was not significant. Procainamide prolonged the shortest pre-excited RR interval (228 +/- 41 to 339 +/- 23 ms, p = 0.0001) as did propafenone (215 +/- 40 to 415 +/- 198 ms, p = 0.0001) and the magnitude of increase was greater for propafenone (p = 0.048). Patients with sustained atrial fibrillation had shorter mean AA intervals than did their counterparts with nonsustained atrial fibrillation (123 +/- 25 versus 186 +/- 35 ms, p = 0.0001). Termination of sustained atrial fibrillation by either drug was accompanied by prolongation of the mean AA interval but not necessarily by the shortest pre-excited RR interval. Termination of atrial fibrillation was heralded by a 68% increase in the mean AA interval after procainamide administration compared with a 30% increase when the arrhythmia persisted. For propafenone the increases were 90% and 68%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1989

The diagnostic sensitivity of electrophysiologic testing in patients with syncope caused by transient bradycardia.

Although electrophysiologic testing accurately delineates abnormalities in patients with fixed cardiac-conduction defects, its sensitivity in identifying transient rhythm disturbances is unknown. We prospectively studied 21 patients who had electrocardiographically documented intermittent atrioventricular block (n = 13) or sinus pauses (n = 8) causing syncope, but whose cardiac rhythm had reverted to normal by the time of referral. There were 14 men and 7 women, with a mean age (+/- SD) of 63 +/- 13 years. Fourteen patients had organic heart disease, and 8 were taking cardioactive medications. Electrophysiologic testing was performed before the implantation of a permanent pacemaker. Only three of the eight patients with documented sinus pauses had abnormalities during their tests that suggested the correct diagnosis (sensitivity, 37.5 percent), including a prolonged sinus-node recovery time in one and carotid-sinus hypersensitivity in two. Three of the eight patients had abnormalities detected that were unrelated to syncope, including atrial flutter, dual atrioventricular nodal pathways, and sustained monomorphic ventricular tachycardia. Of the 13 patients with documented atrioventricular block, only 2 had abnormalities suggesting the correct diagnosis (sensitivity, 15.4 percent). Additional observations unrelated to syncope among these 13 patients included abnormal sinus-node function, atrial flutter, and atrial fibrillation causing hypotension. These preliminary observations suggest that a negative electrophysiologic test in a patient with a normal cardiac rhythm who has experienced syncope does not exclude a transient bradyarrhythmia as a cause of the syncope. Furthermore, electrophysiologic testing may sometimes reveal unrelated rhythm disturbances that may mistakenly be designated as the cause of the syncope.

Aged↗
PubMed1989

Operative therapy of atrioventricular node reentry and results of an anatomically guided procedure.

Operative therapy for atrioventricular (AV) node reentrant tachycardia consisting of dissection guided by anatomic landmarks is described. Of the 21 patients studied, 17 had the common type ("slow-fast") and 4 had the uncommon type ("fast-slow") of AV node reentry. Under normothermic cardio-pulmonary bypass, perinodal dissection was performed guided by anatomic landmarks: the atrial membranous septum, posterior superior process of the left ventricle, tendon of Todaro and os of the coronary sinus. There were no deaths or major complications. Seven to 10 days postoperatively, all patients had normal AV conduction except for one who continued to have AV node Wenckebach-type block. Postoperatively, the shortest cycle length capable of 1:1 conduction over the AV node changed from 323 +/- 66 to 421 +/- 90 ms (p less than 0.0001) anterogradely and from 330 +/- 86 to 449 +/- 164 ms (p = 0.004) retrogradely. Anterograde effective refractory period of the AV node prolonged from 264 +/- 49 to 358 +/- 107 ms (p = 0.012). Discontinuous AV conduction curves were no longer seen in 14 of 17 patients and 5 patients lost retrograde conduction. During follow-up (14.8 +/- 8.2 months), 19 patients have been free of arrhythmia without medication. Two patients required a second operation for recurrent tachycardia with success. No patient required a permanent pacemaker. These data show that operative therapy of AV node reentrant tachycardia can be guided by anatomic landmarks. Successful cure of tachycardia with perinodal dissection while preserving AV node conduction supports the view that the reentrant circuit is, at least in part, perinodal.

Adolescent↗
PubMed1989

Results of operative therapy in the permanent form of junctional reciprocating tachycardia.

To assess the results of operative therapy for permanent junctional reciprocating tachycardia, a type of incessant tachycardia, the clinical and electrophysiologic data of 8 such patients referred for management of tachycardia were reviewed. The duration of incessant tachycardia was 14 +/- 10 years (range 2 to 30). The heart rate at rest during tachycardia ranged from 120 to 150 beats/min. Four of 8 patients had cardiomegaly or depressed ejection fraction (16 +/- 10%, range 5 to 27) at presentation and, of these, 2 had symptoms of congestive heart failure. Exertional dyspnea despite normal left ventricular function was noted in 1 patient, 2 had chronic palpitations and 3 were asymptomatic. Electrophysiologic data confirmed the presence of a posteroseptal pathway with atrioventricular node-like properties conducting slowly in the retrograde direction only. Seven patients underwent successful surgical ablation of the accessory pathway. Hypothermic cardiopulmonary bypass was used in 2 and a closed heart technique without cardiopulmonary bypass in the other 5. Three of 4 patients with reduced left ventricular function showed an improvement in ejection fraction to 34 +/- 20% (range 16 to 63) after control of dysrhythmia. Three patients had no evidence of cardiomegaly despite equivalent periods of incessant tachycardia. Another patient with normal left ventricular function despite incessant tachycardia for over 30 years underwent spontaneous remission to sinus rhythm and did not undergo surgery. These data suggest that permanent junctional reciprocating tachycardia has a variable presentation and that congestive heart failure is not an infrequent presenting symptom. The substrate is invariably an accessory atrioventricular pathway with a long conduction time and decremental properties conducting only in the retrograde direction.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1989

Acute effect of disopyramide on atrial fibrillation in the Wolff-Parkinson-White syndrome.

Disopyramide was administered intravenously to 54 patients during atrial fibrillation and predominantly pre-excited QRS configuration at the time of electrophysiologic study. All patients had Wolff-Parkinson-White syndrome and no patient had coexistent heart disease. The drug was given during sustained atrial fibrillation (n = 45) or during sinus rhythm before induction of atrial fibrillation for patients whose atrial fibrillation was self-terminating in the control state (n = 9). Atrial fibrillation converted to sinus rhythm within 15 min after disopyramide in 37 (82%) of the 45 patients. The shortest RR intervals between two pre-excited cycles increased from 208 +/- 42 to 293 +/- 117 ms (p less than 0.0001). The average RR interval of all cycles prolonged from 332 +/- 60 to 396 +/- 117 ms(n = 45, p less than 0.0001). The 9 patients in whom pre-excitation was abolished after the drug had a significantly longer initial shortest RR interval than that of the 36 patients in whom pre-excitation persisted (246 +/- 47 versus 199 +/- 36 ms, p = 0.0022). No patients developed significant hemodynamic or other adverse effects after disopyramide. These data support the intravenous use of disopyramide in patients with normal ventricular function who have atrial fibrillation and a predominant ventricular response over an accessory atrioventricular pathway.

Adolescent↗
PubMed1989

Effects of time to defibrillation and subthreshold preshocks on defibrillation success in pigs.

The purpose of this study was to examine the effects of: (1) time to defibrillation and (2) subthreshold preshocks on defibrillation success. We conducted two separate experiments in 19 anaesthetized, open-chested pigs. Defibrillation was attempted using the sequential pulse technique approximately 10 s after electrically induced ventricular fibrillation. Each sequential pulse shock consisted of two trapezoidal pulses (approximately 3 ms duration), separated by 0.2 ms. Current was delivered to three mesh electrodes (TX-7, Medtronic) sutured over the anterior right ventricle, posterior right ventricle, and lateral left ventricle. For each animal, defibrillation threshold (DFT) defined as the lowest delivered energy that defibrillated the heart, was measured twice and the average was designated as mean DFT. The energy at 1.4 times the specific mean DFT for each pig was designated as the test shock and 100 volts less than the mean DFT was designated as the preshock. In the first experiment, test shocks were delivered at five different fibrillation intervals (10, 20, 40, 60, and 90 s). Time to test shock delivery was randomized for 10 to 60 s, but, 90 s was always tested at the end of the study. Percentages of success at 10, 20, 40, 60, and 90 s were 94, 78, 94, 83, and 100%, respectively (p = NS). The 12 pigs in which all initial test shocks were successful were selected for the evaluation of post defibrillation arrhythmias. The cumulative incidence of complete heart block lasting at least 5 s were 8, 33, 83, 83, and 83%, respectively. The incidence of complete heart block increased significantly at 40 s (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Atrioventricular nodal tachycardia in the absence of retrograde conduction.

A patient with atrioventricular (AV) nodal reentrant tachycardia assessed by electrocardiographic and electrophysiological criteria is described. During ventricular pacing, retrograde conduction was absent at the longest cycle length tested with the site of block determined to be the AV node by concealed conduction criteria. These findings localize the tachycardia circuit above the His bundle and exclude a His-atrial bypass tract as the retrograde limb of the tachycardia circuit in this patient.

Adult↗
PubMed1987

Acute myocardial infarction: thrombotic complications of nephrotic syndrome.

Thrombotic complications are common in patients with nephrotic syndrome. We report a case of acute inferior wall myocardial infarction in a nephrotic patient secondary to a thrombotic occlusion of the right coronary artery which was subsequently documented to be free from any significant atherosclerotic disease.

Cardiac Catheterization↗
PubMed1980

Modern methods of investigation in speech production.

Methodologies of speech research with respect to the production processes are discussed, with an emphasis on the recent development of new instrumental techniques. It is argued that systematic studies of large amounts of speech data are necessary to understand the basic characteristics of speech. The traditional notion of phoneme-size segments seems inappropriate for interpreting multidimensional articulatory movements by a concatenative model. Experimental means such as a computer-controlled X-ray microbeam technique and advanced statistical processing, in combination with a new theoritical framework of phonetic description, promise future development.

Computers↗
PubMed1979

A stereo-fiberscope with a magnetic interlens bridge for laryngeal observation.

A stereoscopic method of observation of the larynx and the pharynx during speech utterances has been devised, making use of fiber-optic cables and a magnetic bridge. The cables are inserted via the subject's nostrils. The bridge makes the two objective lenses at the tips of the cables abut within the pharynx near the uvula, and the two images viewed through the separate lenses at the prescribed mutual distance are recorded on each frame of a 16-mm film side by side for computer processing of the three-dimensional data.

Fiber Optic Technology↗
PubMed1979

Mandible height and syllable-final tenseness.

Mandible movements in the vowel-to-consonant transition manifest consistent differences between /t/ and /d/ in syllable final position. Both mandible position at its peak value near the articulatory release of the stop and velocity of its ascending movement in the transition are found to be apparently relevant to the tense/lax distinction, even though the reliability of these criteria for categorizing t/d data somewhat varies depending on the speaker. Some related characteristics of lingual movements and similar mandible characteristics for the k/g distinction are mentioned. The data were obtained by the computer-controlled X-ray microbeam system in cooperation with the University of Tokyo group.

Humans↗