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Biomedical subjects

T O Cheng

Publications and source records attributed to T O Cheng.

At least 451 records · Page 25Linked to original sources
PubMed1992

Nonoperative treatment of membranous obstruction of the inferior vena cava by percutaneous balloon transluminal angioplasty.

Percutaneous transluminal angioplasty (PTA) was performed with the Inoue balloon catheter in nine patients with membranous obstruction of the inferior vena cava (MOVC) between November 1988 and April 1991. There were five men and four women, aged 30.8 +/- 8.5 years. Two patients had had previous surgical treatment. Three patients had complete and six had incomplete MOVC. The caval pressure below the MOVC was 24.0 +/- 5.6 and 11.8 +/- 5.3 mm Hg (p less than 0.0001) before and after PTA, respectively. The caval diameter at the site of MOVC increased from 1.5 +/- 1.7 to 20.3 +/- 2.6 mm (p less than 0.0001), and the maximal caval diameter below the MOVC decreased from 28.7 +/- 12.9 to 19.8 +/- 9.9 mm (p = 0.006), before and after PTA, respectively. One patient died of massive pulmonary embolism following successful PTA. All the other eight patients remained asymptomatic during an 18.5 +/- 11.5 months (range 3.5 to 32) follow-up period. Two-dimensional ultrasonograms showed no recurrence of MOVC. We conclude that PTA with the Inoue balloon catheter is an effective and safe alternative to surgical treatment of MOVC.

Adult↗
PubMed1992

Biplane transesophageal echocardiography: an anatomic-ultrasonic-clinical correlative study.

In 427 subjects TEE was performed with either a uniplane or biplane transducer; in seven cadavers the cardiac anatomic segments were observed in several levels and directions. Nine transverse and six longitudinal views were compared with the corresponding cardiac anatomic segments. Based on this correlative study, the levels of segments, insertion depth, anatomic structure identification, image characteristics, clinical applications, and the advantages as well as the limitations of biplane TEE are discussed.

Adolescent↗
PubMed1992

The relationship between intracardiovascular smoke-like echo and erythrocyte rouleaux formation.

Intravascular smoke-like echo always appears in regions of stasis, but the exact mechanism of its production is unclear. We investigated its appearance in relation to erythrocyte rouleaux formation. To study this relationship we performed a series of in vitro and animal experiments. In the in vitro study, we observed an erythrocyte suspension by ultrasonography and found it to be echo-free. Under the microscope, red blood cells were observed in a dispersed state. If an equal amount of lymphocyte separation solution was added to the suspension, smoke-like echo appeared, and red blood cells were seen in a rouleaux pattern. In animal (mongrel dogs) experiments, under physiologic conditions with normal blood flow velocity, all cardiac cavities and the inferior vena cava were echo-free. When stasis was induced experimentally in the inferior vena cava, red blood cells aggregated to form rouleaux and smoke-like echo appeared. On resumption of normal blood flow, the rouleaux dispersed to form erythrocytes again. The mechanism of production of intracardiovascular smoke-like echo is closely related to the formation of erythrocyte rouleaux. When rouleaux are formed, they become larger and appear nearer or larger than the ultrasonic wavelength. Thus reflections are produced and smoke-like echo appears.

Animals↗