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Biomedical subjects

N Niimi

Publications and source records attributed to N Niimi.

44 records · Page 3Linked to original sources
PubMed1977

Diagnosis of high posterior infarction: experimental study through the use of body surface isopotential maps.

This investigation was designed to diagnose high posterior infarction easily through the use of body surface isopotential maps. High posterior infarction was experimentally caused by ligation of the branch of the circumflex artery of the canine left coronary artery. Each dog had a series of maps recorded before and four weeks after experimentally induced myocardial infarction. The common features of maps in high posterior infarction are: 1) The positive area expanded into the dorsal surface so slowly that, in the middle stage of the ventricular depolarization, a large area of the dorsal surface was still covered by the negative area. 2) from the middle to the late stage, the absolute value of the minimum significantly decreased and absolute potential of the dorsal surface also significantly decreased. In conclusion, we propose that it is possibile to diagnose high posterior infarction through the use of maps.

Animals↗
PubMed1977

Genesis of body surface potential distribution in right bundle branch block.

In order to investigate the specific sites of conduction block in the three types (I, II, III) of right bundle branch block (RBBB) classified by body surface isopotential maps, the simulation of ventricular propagation process and mathematically reconstructed maps were used. Four assumptions were introduced from the results of clinical observations and animal experiments. The maps reconstructed from two of these assumptions, in which the conduction block was placed on the main stem of the right bundle branch, showed two different patterns at late stages of excitation, and these two kinds of map resembled Types I and II in clinical maps, respectively. The maps reconstructed from the other two assumptions, in which the site of the conduction block was located mainly in the Purkinje system of the right ventricular free wall, resembled Type I at the late stage of excitation in one of two assumptions and agreed with Type III through all stages of excitation in other case. Based on the above results, it is speculated that the differences of ranges and degrees of conduction block ascribed to abnormal activation in the Purkinje system of the right ventricular free wall are responsible for the genesis of clinical RBBB map patterns.

Bundle-Branch Block↗
PubMed1977

Body surface potential distribution following the production of right bundle branch block in dogs. Effects of breakthrough and right ventricular excitation on the body surface potentials.

Right bundle branch block (RBBB) was produced in five dogs by incising the main right bundle branch. Body surface isopotential maps of each of these dogs were obtained from 85 thoracic electrocardiograms using a mini-computer technique. In addition, the epicardial activaton process was obtained from the same dog, and were correlated with the map pattern. Following the incision, the following characteristic changes in the map pattern occurred: The ventricular activation was prolonged in RBBB as compared with normal. During the early stage of ventricular excitation, the maximum was shifted leftward due to the activation wavefronts in the left ventricle in contrast to the double septal activation in the control. A localized lower potential area (a concavity) which appears in the middle stage of activation within the anterior positivity as an initial representation of breakthrough was also shifted left-and-downward and delayed in appearance. The sudden change in the potential distribution subsequently observed occurred quite differently. The terminal excitation was characterized by the maximum occurring over the right chest in RBBB in contrast to the left chest in control. These changes in the pattern of the potential distribution were compatible with the changes in the ventricular excitation process. This result may be applied to human RBBB map interpretation.

Action Potentials↗
PubMed1976

Experimental studies on the antiarrhythmic action of a lidocaine analog.

The electrophysiologic properties of a lidocaine analog (Kö 1173) was experimentally studied in 41 mongrel dogs. The threshold for occurrence of repetitive ventricular extrasystoles was significantly raised by the administration of 2, 4, and 8 mg/kg of the drug, while atrioventricular and intraventricular conduction times were not affected. After ligation of the anterior descending branch of the left coronary artery, the threshold for occurrence of repetitive ventricular extrasystoles was significantly lowered before the administration of Kö 1173 but it returned to control values after the administration 1 mg/kg of the drug. The strength-interval curve shifted profressively to the right when the dose was increased from 2 to 4 and 8 mg/kg. These results indicate that Kö 1173 prevents the decrease in threshold for occurrence of repetitive ventricular extrasystoles in acute coronary insufficiency at a dose which does not affect the conduction system.

Animals↗
PubMedDate not supplied

Secondary excision of choledochal cysts after previous cyst-enterostomies.

BACKGROUND/AIMS: Patients with a choledochal cyst previously treated by internal drainage should undergo secondary cyst excision. The results of such secondary excisions have not yet been reported. METHODOLOGY: Over a 27-year period, 121 patients underwent excision of a choledochal cyst at our hospitals. Of these, 14 patients underwent secondary cyst excision following internal drainage. These patients were compared retrospectively with the remaining 107 patients who underwent primary cyst excision. RESULTS: Blood loss and operative time were greater, and early and late post-operative complications were significantly more frequent in the secondary excision group. Wound infection (early complication), pancreatic stones (late complication), and hepatolithiasis (late complication) were significantly more common in the secondary excision group. Histologically, inflammation and biliary glands were more frequently seen in the resected bile ducts in the secondary excision group. CONCLUSIONS: The long-term results of secondary excision of choledochal cysts are worse than after primary excision. The frequent late complications may be related to the development of biliary glands as a consequence of cyst-enterostomy.

Adolescent↗