Biomedical subjects

T Niibori

Publications and source records attributed to T Niibori.

12 recordsLinked to original sources

PubMed2000

Use of three-dimensional computed tomography images in deciding the approach for ministernotomy operations.

BACKGROUND: In ministernotomy operations for valvular and congenital heart diseases, several approaches exist. Because topographical relationships of the sternum, ribs, heart, and great vessels differ slightly with each patient, three-dimensional (3D) computed tomography (CT) images are valuable in deciding the best approach for each patient. METHODS: Ministernotomy patients were studied preoperatively using 3D-CT images. By subtracting some parts of the sternum and the ribs from the 3D images, the topographical relationships of the structures were revealed. RESULTS: Different methods of approach (ie, the site, shape, and length of partial sternotomy) were compared on the 3D images of each patient to decide the most appropriate incision. The images were shown to resemble closely the actual operative field. CONCLUSIONS: Three-dimensional CT images are valuable in preoperative planning of ministernotomy, and are essential to individualized planning for each operation.

Humans↗

PubMed1990

Rate-dependent threshold changes during atrial pacing: clinical and experimental studies.

In 36 patients undergoing a permanent right atrial pacing for the treatment of sick sinus syndrome and/or atrioventricular block, the stimulation threshold was determined at a wide range of pacing rates (60 to 120 beats/min) 7 to 10 days after the lead implantation. Twenty-nine (80%) of these cases showed rate-dependent threshold changes, with significantly lower thresholds at higher than lower pacing rates (e.g., 2.91 +/- 1.01 mA at 70 beats/min and 2.32 +/- 0.75 mA at 120 beats/min, P less than 0.01). Thus, with a fixed, smaller current strength, the stimuli often failed to capture the right atrium at lower rates, but caused a 1:1 capture at higher rates. In an echocardiographic study in another series of eight patients, the end-diastolic diameter of the left atrium was decreased from 3.2 +/- 0.9 to 2.7 +/- 0.8 cm (P less than 0.01) when the pacing rate was increased from 60-70 beats/min to 100-120 beats/min. In experiments using two anesthetized, open-chest dogs, a rapid withdrawal of 500 mL of arterial blood reduced the right atrial dimension. This was accompanied by an increased amplitude of the right atrial endocardial electrogram, and the initially subthreshold stimuli became effective in capturing the atria. It was concluded that (1) rate-dependent threshold changes were commonly observed in the early stage of atrial pacing, and (2) fluctuations in the electrode contact with the endocardium appeared responsible for such threshold changes.

Animals↗

PubMed1989

[Surgical treatment of a case of arrhythmogenic right ventricular dysplasia with local myocardial resections].

A 39-year-old man who was diagnosed as ARVD (arrhythmogenic right ventricular dysplasia) with nonischemic sustained ventricular tachycardia (VT) was successfully treated by surgical resection of two parts of the right ventricular free wall, one was the site of earliest excitation during induced VT and the other was an area where delayed potentials were detected during sinus rhythm. A surface mapping was made by means of a computer guided system. A preoperative study of endocardial mapping and a programmed electrical stimulation test were an useful adjunct for surgical management of ARVD. After surgery VT could not be induced by triple extrastimuli and up to now there has been no recurrence of VT more than 2 years after surgery without medication.

Adult↗

PubMed1986

Development of glassy carbon electrode (Dead Sea scroll) for low energy cardiac pacing.

We have developed a new type of glassy carbon electrode whose smooth surface with scattered craters reduces its polarization voltage. It has both excellent antithrombogenicity and slight tissue reaction. The energy threshold curve was the lowest when compared to the Siemens (411S, 412S) and the Solin (S-100) electrodes.

Carbon↗

PubMed1986