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Biomedical subjects

K Hirao

Publications and source records attributed to K Hirao.

At least 19 recordsLinked to original sources
PubMed1992

Atrioventricular nodal reentrant tachycardia with retrograde block induced by aprindine.

Two patients are described who had atrioventricular nodal reentrant tachycardia (AVNRT) with 1:1 relationship in the control state, but in whom a varying degree of VA block during AVNRT was observed during therapy with aprindine. Aprindine, however, did not cause anterograde blockade of conduction over the slow AV nodal pathway during tachycardia. These observations support the conclusion that the bulk of atrial muscle is not a requisite part of the tachycardia circuit in AVNRT and that antiarrhythmic drugs may have disparate effects on conduction in the retrograde and anterograde limbs of the circuit.

Adult↗
PubMed1992

Retrograde supernormal conduction, gap phenomenon in concealed accessory atrioventricular pathways.

We present four patients with the Wolff-Parkinson-White syndrome who exhibited retrograde supernormal conduction or gap phenomenon in concealed accessory pathways. In the first patient, ventricular extrastimulus testing revealed retrograde block at the coupling interval of 520 msec and reappearance of conduction at the coupling interval of 370 msec. In a second patient, 1:1 retrograde conduction was not present but supernormal conduction was demonstrated at coupling intervals of 360 msec to 310 msec during the ventricular extrastimulus testing when the basic drive consisted of atrioventricular (AV) simultaneous pacing. In a third patient, ventricular extrastimulus testing demonstrated retrograde conduction through the accessory pathway only at coupling intervals of 400 msec to 360 msec. In a fourth patient, retrograde block occurred at the coupling interval of 340 msec and retrograde "slow" conduction reappeared at coupling intervals of 300 msec to 250 msec (gap phenomenon) only when the basic drive consisted of AV simultaneous pacing. Thus, concealed accessory pathways may exhibit retrograde supernormal conduction or gap phenomenon. Ventricular extrastimulus testing consisting of AV simultaneous pacing during the basic drive may facilitate demonstration of these unusual properties.

Adult↗
PubMed1992

A study of fracture and inelastic behavior of bioactive glass-ceramics and glasses.

The fracture and inelastic behavior of A-W glass-ceramics, phosphate glasses, silicate glasses, and borate glasses were determined in simulated body fluid (SBF), kerosene, and water. By using the stable crack growth technique, an inelastic behavior was observed on the diagram of load versus load-point displacement. From these studies, it was suggested that the inelastic behavior of bioactive glass-ceramics was produced by the plastic deformation of glassy phase on the grain boundary.

Apatites↗
PubMed1991

Combination therapy with aprindine and verapamil for paroxysmal supraventricular tachycardia as assessed by transesophageal atrial pacing.

UNLABELLED: To assess the efficacy of combination therapy of aprindine (40 mg/day) and verapamil (160 mg/day), transesophageal programmed atrial stimulation was performed on 21 patients with paroxysmal supraventricular tachycardia (including 12 patients with atrioventricular nodal reentrant tachycardia and nine patients with atrioventricular reentrant tachycardia) under four conditions: a) control, b) aprindine alone, c) verapamil alone, and d) aprindine + verapamil. RESULTS: a) Aprindine, verapamil, and aprindine + verapamil prevented paroxysmal supraventricular tachycardia induction in 2/21, 3/21, and 9/21 patients, respectively; b) aprindine + verapamil prolonged the cycle length of paroxysmal supraventricular tachycardia more than aprindine or verapamil alone; c) aprindine, verapamil, and aprindine + verapamil decreased the AV blocking rate by 15, 23, and 35 beats/min, respectively, in comparison with the control state; d) aprindine, verapamil, and aprindine + verapamil prolonged the effective refractory period of atrioventricular conduction system by 20, 34, and 76 msec, respectively, compared with the control state. In conclusion, aprindine + verapamil appear to be more effective than aprindine or verapamil alone in preventing paroxysmal supraventricular tachycardia with nodal reentry, but there was less benefit in those without nodal reentry (Wolff-Parkinson-White group).

Administration, Oral↗
PubMed1991

Pathological aspects of radiofrequency catheter ablation of the canine atrioventricular node and bundle of His. With special reference to chronic incomplete atrioventricular block.

Radiofrequency catheter ablation of the atrioventricular (AV) node or bundle of His was performed in 12 adult mongrel dogs. The aim was to create chronic incomplete AV block (first- and second-degree AV block) and to examine the histopathology of the ablated lesions. However, the late electrophysiological results (2-4 weeks follow-up) were various: normal in 2 dogs, mild PR prolongation (less than 50%) in 2 dogs, first-degree AV block (PR prolongation greater than or equal to 50%) in 2 dogs, second-degree AV block in 2 dogs, complete AV block in 4 dogs. The maximally ablated area (%) of the atrioventricular conduction system in serial histologic sections from dogs with these conditions was 69%, 75%, 89.5%, 95% and 99.5%, respectively. The number of intact conduction cells at the maximally ablated site varied from 6 to 30 in the four cases of incomplete AV block. The mean ablated volume (%) of either the AV node or penetrating His bundle correlated roughly with the degree of AV block. The ablated lesions were well demarcated and almost replaced by dense fibrous tissue at 4 weeks. Interruption (3 dogs) or thinning (1 dog) of the endocardial elastic lamellae was detected, in association with endocardial thickening (mean 913 microns). Endocardial thrombi were found in 3 dogs (2 fresh, 1 organized). We conclude that radiofrequency catheter ablation does not cause severe complicated lesions. Several possible conditions for creating chronic incomplete AV block are discussed.

Animals↗
PubMed1991

Demonstration of right and left atrial dissociation by atrial rapid pacing or extrastimulation during fast-slow (uncommon) form of atrioventricular nodal reentrant tachycardia.

Some recent works suggest that extranodal atrial fibers may form part of the reentry circuit in the atrioventricular (AV) nodal reentrant tachycardia (AVNRT). This hypothesis is based on the fact that the perinodal dissection successfully abolished AVNRT while preserving intact AV conduction. Apart from the surgical success, the electrophysiological evidence supporting this hypothesis has not been demonstrated, especially in the uncommon (fast-slow) form of AVNRT. We present some electrophysiological evidence suggesting atrial participation in eight patients with the fast-slow form of AVNRT. During the tachycardia, rapid pacing or extrastimulation was done from the orifice of the coronary sinus (CS) and the right atrium (RA), while recording the electrograms of the CS and the low septal RA. In seven patients, right and left atrial dissociation was demonstrated during pacing from the RA, while in the remaining one this was demonstrated from the CS. The interatrial dissociation will be unlikely if the intranodal reentry circuit connects with the atria via a single upper common pathway. This suggests that the upper turnaround of the reentry circuit involves atrial tissue and that the extranodal accessory pathway with long conduction times may form the ascending limb of the circuit (atrionodal reentry). Alternatively, the reentry circuit is entirely intranodal and two or more connecting pathways are present between the atria and the circuit.

Adult↗
PubMed1991

[A case of penile cavernitis following a penile prosthesis implantation].

A 25-year old man, who had an inferiority of having a small penis and normal potency, underwent intracavernous implantation of hand-made silicone rods by a cosmetic surgeon in order to enlarge his penis. He had pyrexia and swelling of the penis 2 days after the implantation, and penile cavernitis developed. The penile symptoms improved by drainage and strict chemotherapy, and then the silicone rods were removed from his penis. Histopathological findings of the corpus cavernosum showed marked inflammatory and granulomatous changes. The patient lost his potency due to poor blood flow into the cavernous.

Adult↗
PubMed1991

[A case of squamous cell carcinoma of the urinary bladder associated with bladder calculi].

A case of squamous cell carcinoma of the urinary bladder associated with a bladder stone in a 43-year-old man is reported. Because a 1 cm x 1 cm sized mass was found in the right lateral side of the dome at the time of vesicolithotomy, partial cystectomy was performed. The weight of the stone was 285 g and the tumor was histologically diagnosed as squamous cell carcinoma, grade 2, pT2. Radical cystectomy with ileal conduit was sandwiched by a total of 6 cycles of chemotherapy with PVB. Twelve cases of squamous cell carcinoma of the urinary bladder associated with a bladder stone(s) from the Japanese literature are reviewed, and the relationship between bladder stone, leukoplakia and squamous cell carcinoma discussed.

Adult↗
PubMed1989

Electrophysiological demonstration of anterograde concealed conduction in accessory atrioventricular pathways capable only of retrograde conduction.

Anterograde concealed conduction into the concealed accessory atrioventricular (AV) pathway has been postulated to be one of the factors preventing the reciprocating process via the accessory pathway in patients with the concealed Wolff-Parkinson-White(WPW) syndrome but its presence has not been documented. To demonstrate the occurrence of anterograde concealment, 12 patients with the concealed WPW syndrome were selected for study. A pacing protocol was designed in which the retrograde conduction of the ventricular extrastimulus over the accessory pathway was assessed during ventricular pacing alone (conventional method) and during the AV simultaneous pacing (simultaneous method); the results were then compared. When the high right atrium was simultaneously paced, the effective refractory period of the concealed accessory pathway shortened as compared with the conventional method in five of 12 patients (from 341.7 +/- 110.8 to 312.5 +/- 108.2 msec, n = 12), whereas, it decreased in all patients studied when the coronary sinus near the accessory pathway was simultaneously paced (from 375.7 +/- 135.0 to 287.1 +/- 116.1 msec, n = 7). These results demonstrate that the AV simultaneous pacing frequently shortens the refractoriness of the concealed accessory AV pathway and such facilitation seems to be well explained by the probable anterograde concealment in it and peeling back of the refractory barrier.

Atrioventricular Node↗
PubMed1989

Exophytic spread of hepatobiliary disease via perihepatic ligaments: demonstration with CT and US.

Eight cases of hepatobiliary disease located adjacent to or within the perihepatic ligaments (peritoneal reflections surrounding the liver) with exophytic spread along these ligaments (three abscesses from cholecystitis, two bilomas, two hepatic abscesses, and one hematoma from a ruptured hepatocellular carcinoma, with 16 ligamentous lesions: five in the hepatoduodenal ligament, four in the ligamentum teres, three in the falciform ligament, two in the gastrohepatic ligament, one in the transverse mesocolon, and one in the duodenocolic ligament) were studied with sonography and computed tomography. The locations of underlying diseases were the inferior aspect of the left lobe of the liver (three patients), the gallbladder (three patients), and the right hepatic duct (two patients). An understanding of the anatomic detail of the ligamentous attachments of the liver and the continuity of peritoneal ligaments is important in recognizing the ligamentous spread of hepatobiliary disease. This mode of spread of disease should be kept in mind in diagnostic imaging of the abdomen.

Abscess↗
PubMed1989

[A case of hepatoma treated successfully with a percutaneous intratumoral injection of CDDP-PC-lipiodol suspension].

Reported is a case that was treated successfully with a percutaneous intratumoral injection of a CDDP-PC-Lipiodol Suspension (CPLS) of the viable tumor cells of a hepatoma after arterial injection therapy. Although the size of the viable tumor cells remained almost unchanged, a marked reduction in the level of the plasma AFP (484 ng/ml-35 ng/ml) was obtained after the percutaneous injection. No major complication was encountered except for minimal vomiting and mild transient abnormalities of the liver functions.

Aged↗
PubMed1989

Reconstruction of sigmoid vagina and conduit in total pelvic exenteration for recurrent cervical carcinoma.

Although total pelvic exenteration is performed for central recurrent or persistent uterine cervical carcinoma, the patient is damaged both physiologically and psychologically by its massive surgical procedure and complications as well as the loss of the vagina. Vaginal reconstruction at the time of surgery brings much advantageous satisfaction to the patient's future life and a strong bond with her husband. Furthermore, a new reconstructed vagina occuping the pelvic cavity prevents intestinal herniation and is available for bimanual examination in the follow-up to surgery. A case of recurrent cervical carcinoma is presented, with reconstruction of the vagina and conduit using the sigmoid colon in total pelvic exenteration.

Carcinoma, Squamous Cell↗