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Biomedical subjects

N Tanigawa

Publications and source records attributed to N Tanigawa.

At least 127 records · Page 7Linked to original sources
PubMed1992

[The influence of atrioventricular asynchronous contraction on left and right ventricular performance].

To investigate the influence of atrioventricular asynchronous contraction on left and right ventricular performance, pulsed Doppler echocardiographic studies were performed in 10 patients who received permanent pacemaker (VVI mode), but without significant heart disease except for complete heart block. After setting the pacing rate at 40 per min, the performance was analyzed during the patient's own slow ventricular rate. Flow velocity patterns at the left (LVOT) and right ventricular outflow tracts (RVOT) were recorded by pulsed Doppler echocardiography, and ejection time (EjT), acceleration time (AcT), peak velocity (PV) and flow velocity integral (FVI), which is proportional to stroke volume, were measured for each outflow tract. When the patient's own atrial contraction occurred during ventricular systole, EjT, AcT, PV and FVI of flow at the LVOT and EjT, AcT and FVI of flow at the RVOT were decreased. Percent change of the FVI of flow at the RVOT (-34.6%) was significantly greater than that of flow at the LVOT (-16.2%, p < 0.01). These results indicate that the loss of right ventricular performance might play a prominent role in the genesis of the hemodynamic deterioration with atrioventricular asynchronous contraction.

Adult↗
PubMed1992

[Detection of ventricular late potentials comparison of 4 commercial high-resolution systems].

UNLABELLED: The purpose of this study was to evaluate the methodologic problems of noninvasive registration of ventricular late potentials. METHODS: we compared the results obtained in the same patients with four different systems which were Marquette MAC1, MAC12, ART LP101 and FUKUDA VCM 3000. Filtering was employed digital forward direction, 100-300 Hz in MAC1, digital FFT, 40-250 Hz in MAC12, digital, bidirectional, 40-250 Hz in ART and analogue, forward direction 40-300 Hz in FUKUDA VCM 3000. DEFINITION OF LATE POTENTIALS (LPs): Filtered QRS duration (FQRSD) was 120 msec or more, root mean square voltage in the last 40 msec (RMSV) was 15 microV or less in MAC12 and ART. FQRSD was 130 msec or more, RMSV was 15 microV or less in FUKUDA. FQRSD was 20 msec or more after QRS obtained from low resolution leads in MAC1. SUBJECTS: 163 patients [control 13, PVCs 23, myocardial infarction 55, others 51, IVCD (RBBB, LBBB, IVCD) 21] were included in this study. RESULTS: 17.6% of all patients (except for IVCD) showed LPs with MAC12, 20.0% with ART, 30.3% with FUKUDA, and 14.1% with MAC1. 23.1% of the control group showed LPs with MAC12 and FUKUDA, but no cases showed LPs with ART and FUKUDA. 4.3% of the PVC group showed LPs with MAC12, 13.0% with ART and FUKUDA, but no cases showed LPs with MAC1. 25.5% of the myocardial infarction group showed LPs with MAC12 and MAC1, 30.9% with ART and 36.3% with FUKUDA. All four methods gave corresponding results in 65.4% of patients, 7.0% positive and 58.4% negative findings. FQRSD of MAC12, ART and FUKUDA was 110.2 +/- 18.1 msec, 105.2 +/- 20.4 msec and 125.8 +/- 22.8 msec respectively. Correlation coefficient (r value) in FQRSD was 0.90 between ART and MAC12, 0.74 between ART and FUKUDA, and 0.75 between FUKUDA and MAC12. RMSV of MAC12, ART and FUKUDA was 49.2 +/- 30.2 microV, 43.7 +/- 37.8 microV and 22.5 +/- 10.6 microV respectively. R value in RMSV was 0.59 between ART and MAC12, 0.38 between ART and FUKUDA and 0.43 between FUKUDA and MAC12. R value in high frequency low amplitude signals duration under 40 microV of LPs positive patients in MAC1 was 0.51 between ART and MAC 12, 0.18 between MAC12 and MAC1, and 0.32 between ART and MAC1. Most of the differences result from a different interpretation of the tracings. Especially LPs far from QRS offset could be registered with neither MAC12, ART nor FUKUDA.

Action Potentials↗
PubMed1992

Application of expandable metallic stents to the venous system.

Expandable metallic stents were successfully introduced in 12 patients; 6 with superior vena cava (SVC) obstruction due to tumor invasion or lymph node metastases, 3 with inferior vena cava (IVC) obstruction or stenosis due to lymph node metastases or hepatic tumor, one with common iliac vein (CIV) obstruction due to lymph node metastases, one with idiopathic obstruction of the hepatic IVC and Budd-Chiari syndrome, and one with CIV obstruction following a dialysis shunt. The length of the lesions was between 2 and 15 cm. Multiple (2-7) stents in tandem were inserted percutaneously from a femoral venous approach through a 12 to 16 F (4.0-5.3 mm) Teflon sheath. Postoperatively, all 12 patients became free from symptoms such as SVC syndrome or IVC syndrome. In 11 patients, the symptoms did not recur during the follow-up periods of 1 to 21 months.

Adult↗
PubMed1991

[Clinical experience of expandable metallic stent placement for malignant biliary obstruction].

Expandable metallic stents of modified Gianturco design were used in nine cases of malignant biliary obstruction. Stents were placed through a percutaneous transhepatic approach without any severe complications. Initial patency was obtained seven of nine patients. Of these seven patients, recurrent jaundice was observed in three within four weeks. One patient had recurrent stenosis after four months due to ingrowth of the tumor. Although the expandable metallic stent offers several theoretical advantages over currently available stents, a disadvantage is that tumors may grow through the spaces between the legs of the wire or grow over the stent. We found that multi-modal treatment combined with radiation therapy was indispensable to maintain the patency of the stent in malignant biliary obstruction.

Aged↗
PubMed1991

[An animal experiment on arterial wall reaction to stents coated with gold, silver and copper].

Expandable metallic stents coated with gold, silver, and copper, and bare stainless steel stents were implanted into the abdominal aorta of eight dogs to determine their effect on the vessel wall. The animals were observed for two weeks. Abdominal angiograms were taken every week. The dogs were then killed for macroscopic and histopathological examination. The results were as follows. (1) The stents coated with gold and the noncoated stainless steel stents showed less histopathologic change than the other stents. (2) The stents coated with copper were associated with severe erosion of the vessel wall and marked thrombus formation.

Animals↗
PubMed1991

Significance of surgical adjuvant chemotherapy for gastric cancer.

One hundred and twenty-four specimens (72 primaries and 52 metastases) in 107 patients with gastric cancer were tested using the human tumor clonogenic assay (HTCA). Assays for 64 specimens (52%, 33 primaries and 31 metastases) were considered evaluable. The clonogenicity of the primaries was less than that of the metastases (P less than 0.01). In the primary specimens, well-differentiated tumors were more highly clonogenic than poorly differentiated or signet ring cell tumors (P less than 0.05). Viable malignant cells and clonogenic cells were abundant in the primary tumors with mucosal (m) and submucosal (sm) invasion, i.e., in early gastric cancers by Japanese criteria, and were reduced in numbers as the primary tumors advanced (P less than 0.05). In vitro chemosensitivity corresponded well to the clonogenicity of the primary tumors stratified by the degree of tumor invasion. At the early phase of primary tumor progression and metastasis, clonogenicity and chemosensitivity were high. Aggressive chemotherapy with sensitive drugs after surgery may improve the clinical results for the gastric cancer patients with early phase of metastases.

Adenocarcinoma↗
PubMed1991

Proliferative activity of human tumors: assessment using bromodeoxyuridine and flow cytometry.

Cell kinetics of human carcinoma xenografts and human solid tumors were evaluated by means of two-color flow cytometry using single sampling at appropriate time intervals after bromodeoxyuridine (BrdU) labeling. The tumors were resected several hours after the administration of BrdU, and flow cytometry was used to measure the DNA content and BrdU incorporation. Once the BrdU labeling index (LI) and DNA synthesis time (Ts) were obtained, the potential doubling time (Tpot) was calculated from these values. In 11 xenografts, the cell kinetic data were compared with the actual tumor doubling time (Td), and a good correlation between Tpot and Td was obtained (r = 0.91, P less than 0.005). In a clinical study, 33 patients with gastric cancer, colorectal cancer, lung cancer, or other solid tumors were analyzed. Aneuploid tumors had a significantly higher LI value (P less than 0.01) and a shorter Tpot than diploid tumors. The cell loss rate of human tumors ranged from 40% to 80%. These cell kinetic parameters therefore accurately indicated the level of proliferative activity of human tumors.

Animals↗
PubMed1991

Significance of postoperative early chemotherapy for locoregional lymph node metastases of gastric and colorectal cancer.

Eighty-seven locoregional lymph node metastatic specimens from 52 gastric cancers and 35 colorectal cancers were tested using a human tumor clonogenic assay and the results were analyzed. Experiments were considered evaluable in 31 gastric and 21 colorectal specimens, respectively. Metastatic malignant cells and clonogenic cells per gram of wet specimen were significantly more prevalent in smaller (1.5 g weight or less) involved nodes (p less than 0.005 and p less than 0.025, respectively). The clonogenicity was also higher in the smaller (2.0 g or less) specimens, although the difference was not significant. In vitro chemosensitivity was higher in the smaller nodes and this tendency corresponded well to the clonogenicity. The data showed that the clonogenicity and in vitro chemosensitivity were high in the early phase of locoregional lymph node metastasis, and suggested that perioperative chemotherapy could control lymph node micrometastases and prevent recurrence in patients with gastric or colorectal cancer.

Antineoplastic Agents↗
PubMed1991

The influence of left ventricular relaxation in determination of the intensity of the aortic component of the second heart sound.

In a study of the aortic component of the second heart sound (A2) intensity, using 10 dogs, miniature cardiac accelerometers were attached to the exposed left ventricle (LV) at the apex, and to the surface of proximal aorta, to obtain LV and aortic surface acceleration. Manometer tipped catheters were used to detect aortic systolic pressure and diastolic pressure and time constant of left ventricular pressure fall "T". Drugs (Nitroprusside, Dobutamine and Methoxamine) altered aortic pressure, LV contraction and LV relaxation. When T was +/- 35% of control, the aortic systolic pressure and diastolic pressure were good predictors of A2 intensity. When LV relaxation was impaired, increasing T greater than 135% of control, the A2 intensity for any given aortic pressure was reduced. When relaxation was hyperactive, decreasing T less than 65% of control, A2 intensity was increased. Aortic pressure/T which assessed both aortic pressure and relaxation ability, is a better determinant of A2 intensity than aortic systolic pressure or aortic diastolic pressure alone.

Animals↗
PubMed1991

Endotracheal expandable metallic stent placement in dogs.

Various types of Gianturco zig-zag wire stent were implanted into the tracheas of 4 dogs to define the suitable characteristics of the endotracheal wire stent in these animals. The stents were constructed of 0.45, 0.40, and 0.33 mm stainless steel wire. The diameter of the fully expanded stents was 3 cm and their lengths were 2, 3, and 4 cm. The 2 cm stent constructed of 0.33 mm wire showed minimum pathologic changes of the trachea of the dog compared to the other stents, and at the same time had a complete covering of ciliated columnar epithelium over the stent surface.

Animals↗
PubMed1990

[Experimental study of the intraurethral placement of expandable metallic stents].

Various types of Gianturco expandable metallic stents were implanted into the urethra of four dogs in order to evaluate the suitable expandability of the stents in urethra and also to determine the effect of the stents on the urethral wall. The stent of 1.5 cm in length and constructed of 0.010 inch round stainless steel wire with twelve zigzag bends showed the suitable expandability on the canine urethra compared to the other stents. The urethra remained patent and the inflammatory changes on the urethral wall were moderately noted. No hematuria or calcifications around the stents were noted in any dogs. The experimental data showed a potential clinical application.

Animals↗
PubMed1990

[In vitro study of radiofrequency thermal angioplasty].

We performed some in vitro experiments using a radiofrequency thermal angioplasty instrument. The distribution of heat emitted from the hot tip of the device was evaluated in an agar phantom by thermography and it produced a concentric circular pattern. The temperature of the hot tip was about 290 degrees C when measured by thermocouples in the air. When the RF probe approached perpendicularly to the cadaver arterial wall, a crater with charring and coagulating necrosis was formed. However, when the RF probe traveled parallel to the arterial wall, as in normal practice, it did not seem to perforate the artery. The device could ablate non-calcified atheromatous plaque.

Angioplasty, Balloon↗
PubMed1990

[Fundamental experiment of expansile force of expandable metallic stent].

So far expansile force of expandable metallic stent has been estimated by only wall-distending pressure P. We estimated expansile force of stent by not only P but also a force per one unit length of wire F. F corresponds to the degree of digging into the vessel wall. P and F were thought to be useful in selecting the best stent.

Elasticity↗
PubMed1990

[The clinical role of anaerobic threshold in physical training of patients with recent myocardial infarction].

Twenty-seven patients with recent myocardial infarction were studied to evaluate the clinical usefulness of the anaerobic threshold (AT) in physical training as cardiac rehabilitation at home. The 27 patients were divided into trained and control groups. Symptom-limited treadmill exercise tests were conducted before and six weeks after the prescribed aerobic training. Heart rate (HR), systolic blood pressure and respiratory gases (VO2, VCO2 and VE) were noninvasively measured throughout the exercise periods. AT was defined as systemic increase in the ventilatory equivalent O2 (VE/VO2) without an increase in the ventilatory CO2 (VE/VCO2) during the increasing work load. The patients in the trained group were obliged to perform aerobic walking training requiring 90-100% HR of the AT level for 30 min, four to six days per week. 1. In the trained group, exercise time, peak VO2, and AT on treadmill performance were significantly increased compared with those of the pre-training values. However, in the control group, these parameters were not significantly changed. A significant reduction in double products was observed during submaximal workload in the trained group. 2. Factors related to the training effects: The training effect expressed by delta peak VO2 correlated significantly with the initial peak VO2 (pre-training peak VO2) (y = 35.4 - 1.29x, r = 0.70), but there was no correlation between left ventricular function and delta peak VO2. These results indicated that aerobic exercise at home guided by the AT level is safe and beneficial for patients with recent myocardial infarction.

Anaerobic Threshold↗
PubMed1990

[Valvular regurgitation in patients with complete heart block by color Doppler echocardiography].

We studied valvular regurgitation (pulmonary, aortic, tricuspid and mitral regurgitation) in 30 patients with complete heart block by color Doppler echocardiography, pulse Doppler and continuous wave Doppler echocardiography. The prevalence rate of multivalvular regurgitation of these subjects was 83.3%. Regurgitation involving all four valves appeared in 30.0% of these patients. The prevalence rate of pulmonary, aortic, tricuspid and mitral regurgitation was 56.7%, 33.3%, 100%, and 76.7% respectively. Pulmonary regurgitation (PR) was observed in patients with complete heart block without pulmonary hypertension. PR velocity was slow and interrupted by atrial contraction. It might be possible to evaluate atrial pressure from the interruption of PR. Tricuspid regurgitation (TR) during systole was often present in patients with right ventricular endocardial pacing. Systolic TR was influenced by atrial contraction. When atrial contraction occurred during systole, TR was interrupted, or shortened. Diastolic TR and MR were easily detected by M mode color Doppler echocardiography. The diastolic TR and MR were of slow velocity and appeared 240-290 msec after P wave. These atypical valvular regurgitation in patients with complete heart block reflect of the inverse atrial-ventricular pressure gradient across the atrio-ventricular valve.

Adult↗
PubMed1990

[Physical properties of expandable metallic stents; including the procedure of stent production].

Nowadays expansile force of self-expandable metallic stent is estimated by only wall-distending pressure P. We estimated the expansile force of the stent by not only P but also F. F expressed the degree of digging into the vessel wall and was defined as a force per one unit length of wire. P and F were thought to be useful in selecting the best stent. We also introduced the procedure of stent production.

Biomechanical Phenomena↗