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Biomedical subjects

R Omoto

Publications and source records attributed to R Omoto.

189 records · Page 11Linked to original sources
PubMedDate not supplied

Left and right ventricular flows by Doppler echocardiography: serial measurements in patients with aortic regurgitation during exercise, cold pressor stimulation, and vasodilation.

To test the practicality of Doppler echocardiography to measure serial change, biventricular outputs were measured in 15 patients with aortic regurgitation during control periods and during interventions of bicycle exercise, cold pressor stimulation, and vasodilation. Biventricular stroke volumes were measured in 10 normal subjects for validation of methods and differed by 2.8%. Reading errors were 3.7%. Signal quality improved between the first and last observation (p less than 0.05). Velocity signals were corrected for intercept angles, which averaged 12 and 19 degrees for right heart flows and 31 and 32 degrees for the left side of the heart in all subjects. Negative correlations occurred between intercept angles and the chronologic order in which the patients were studied for left (p = 0.02) and right (p = 0.05) flows. Mean flow areas varied 9% in the left ventricle and 20% in the right ventricle. Total variability for measuring flow determined from control values was 11% to 13%. When twice the variability was used as the detectable level of change, only exercise provoked real increases in biventricular flows in the majority of patients. We conclude that serial measurements of flow by Doppler echocardiographic methods had to exceed 20% to 25% to achieve significant change. Measuring intercept angle, resolving flow area, and learning are variables that need greater emphasis.

Aortic Valve Insufficiency↗
PubMedDate not supplied

Transesophageal color Doppler echocardiography during mechanical assist circulation.

Information available to determine the optimal timing for separation of patients (pts) from mechanical assist circulation (MAC) is usually limited, due to the difficulty of transfer of patients with heavy MAC systems. To evaluate the clinical efficacy of transesophageal color Doppler echocardiography (TEE) in management of patients during MAC, we examined 37 pts (32, intra-aortic balloon pumping = IABP; 4, left ventricular assist device = LVAD; 1, right VAD = RVAD) by TEE. In the other 3 pts, thoracic aneurysms (AN) (2, dissecting An; 1, true AN) were detected by TEE, which were contraindications to safe introduction of IABPs. In 29 pts on IABPs, 2 pts with LVADs, and in 1 pt with a RVAD, patients were safely weaned from MACs with confirmation of full recovery of cardiac function by TEE. However, repeat introduction of IABP support was needed in 2 pts due to severe residual mitral regurgitation, even after initial success; these became the cause of late multiple organ failure. In one pt with a LVAD, a detrimental right to left shunt through the patent foramen ovale, which resulted in severe desaturation of the arterial blood oxygenation, was detected by TEE. Left main coronary flow was measured by TEE and found to increase by 55% on IABP and by 67% on a LVAD. In conclusion, TEE is the only currently available diagnostic tool for total evaluation of cardiac function in an intensive care unit, which can provide very important information for management of patients on MACs.

Adult↗
PubMedDate not supplied

Beneficial effect of fluorocarbon reperfusion on postoperative cardiac dysfunction of transplanted heart.

Fluosol DA 20% (Fluosol) perfusion was used to protect ischemic donor hearts of mongrel dogs from reperfusion injury. Fifteen orthotopically transplanted hearts, eight in the control group and seven in the Fluosol group, were studied for 3 hours after weaning from cardiopulmonary bypass. Donor hearts were arrested and immersed in 4 degrees C St. Thomas's Hospital Solution for 4 hours. The mean total ischemic time was 323 minutes (range, 298 to 345 minutes). In the Fluosol group, 200 ml of oxygenated Fluosol (37 degrees C; PO2 650 mm Hg; PCO2 35 mm Hg) was infused into the aortic root at approximately 100 ml/min just before aortic unclamping. Coronary sinus blood was analyzed for the MB fraction of creatine kinase, reduced glutathione, and oxidized glutathione. Hemodynamic and biochemical results were obtained at 30 minutes, 1 hour, and 3 hours after bypass. In the control group, during the second 30 minutes of the period after bypass, left ventricular end-diastolic pressure and stroke volume showed progressive deterioration, 54.8% increased (p less than 0.01) and 28.4% decreased (p less than 0.05), respectively. The MB fraction of creatine kinase and oxidized glutathione were increased, and reduced glutathione had declined, from 39.3 to 135.3 IU/L (p less than 0.01), from 28.0 to 33.4 micrograms/ml (p less than 0.05) and from 4.4 to 2.5 micrograms/ml (p less than 0.01), respectively. These parameters failed to recover during the next 2 hours, and massive mitochondrial degeneration was observed by electron microscopy. In the Fluosol group, these parameters maintained their baseline values, and electron microscopy showed well-preserved mitochondria. The data suggested that, in the control group, initial mitochondrial dysfunction was profound, persistent for at least 3 hours, and associated with membrane hyperpermeability, leading to cardiac dysfunction. Oxygenated Fluosol perfusion better preserved cardiac and mitochondrial function.

Animals↗
PubMedDate not supplied

Effect of prostacyclin analog on pulmonary edema in isolated heart-lung autoperfusion model.

Pulmonary edema and impaired gas exchange function are worrisome early complications of heart-lung transplantation. The present study was designed to determine the effect of a new prostacyclin analog, OP-41483, on these complications with the use of a heart-lung autoperfusion model. Twenty-four mongrel puppies (4 to 6 kg) were evenly divided into four groups according to the oxygen content of inspired air (group 1, 95%; group 2, 60%) and the use of an intravenous drip of OP-41483 (0.1 microgram/kg/min) (group 3, 95% + OP; group 4, 60% + OP). During the course of these experiments, systolic pressure and cardiac output were maintained constant at 100 mm Hg and 40 ml/kg/min, respectively. Pulmonary arterial pressure was almost constant in each group throughout the experiment. Arterial oxygen tension (Pao2) was significantly decreased in groups 1 (410 +/- 49 to 237 +/- 38 mm Hg, p less than 0.01) and 2 (368 +/- 44 to 243 +/- 26 mm Hg, p less than 0.01) over the 5-hour autoperfusion period but was maintained at a high level in groups 3 (488 +/- 70 to 447 +/- 39 mm Hg) and 4 (431 +/- 33 to 430 +/- 35 mm Hg). Pathologic findings (perivascular edema and capillary dilatation) were significant in group 1 but less marked in group 2. However, no abnormal pathologic changes were observed in groups 3 or 4. These data demonstrated that OP-41483 was effective in preventing functional and pathologic pulmonary disturbances at a dosage (0.1 microgram/kg/min) that is reported to induce no undesirable hemodynamic effect.

Animals↗
PubMedDate not supplied

[Pediatric matrix biplane transesophageal echo probe: evaluation of probe selection in patients].

We have developed four different probes for the wide use of transesophageal echocardiography in children. The adult matrix biplane probe (M-BP) can generate transverse and longitudinal plane images simultaneously from a single transducer, and facilitates easier and faster understanding of the three-dimensional anatomy of the heart. This probe can be used in patients weighing more than 15 kg. The pediatric matrix biplane probe (PM-BP) has the same function as the M-BP in a smaller probe head and shaft, and can be used in patients weighing more than 5 kg. The conventional pediatric biplane probe (P-BP) with two transducers has a smaller probe head profile than the PM-BP, and can be used in a baby as small as 2.7 kg. The newborn single plane probe (N-SP) has the smallest profile with a 4 mm diameter shaft, and can be used like a nasogastric tube. We choose probes according to the size of the patient and purpose of the study. As a rule, smaller probes are less invasive and reduce the risk of the study. However, larger probes have better image quality and penetration. Proper selection of the probe is the key to the safe and effective use of this new methodology.

Child, Preschool↗
PubMedDate not supplied

[Pathological study of the transseptal puncture site of interatrial septum in catheter interventions].

Pathological changes in the transseptal puncture site of the interatrial septum were studied in seven autopsy patients in whom transseptal puncture had occurred during catheter interventions under transesophageal echocardiography monitoring. 1. In one patient with chronic renal failure who had received hemodialysis for more than 10 years, the transseptal puncture was unsuccessful. The failure is attributable to the severe calcification of the left atrial wall and interatrial septum. The autopsy showed only a small scratch on the fossa ovalis in the right atrial side. 2. The puncture hole was round in five patients and a slit in one, without tearing or extension from the puncture hole. 3. Late closure of the transseptal puncture hole was observed in two patients who died 7 and 22 days after the intervention procedures. 4. Mild infiltration of red blood cells around the transseptal puncture hole was detected in two patients. One died immediately after left atrio-arterial bypass support and another died on the 24th day after percutaneous transvenous mitral commissurotomy. Both patients showed tendency to bleeding due to heparinization and/or coagulopathy treatment during the clinical course. 5. Autopsy specimens demonstrated that the transseptal puncture was performed just on the fossa ovalis in all patients. 6. Biplanar transesophageal echocardiography is a very effective guidance method for transseptal puncture during catheter interventions.

Adult↗
PubMedDate not supplied

[Evaluation of the lumen-plaque-wall alterations by intravascular ultrasound imaging after percutaneous transluminal laser angioplasty in peripheral arteries: comparison with angiographic findings].

Intravascular ultrasound imaging was compared to angiography for evaluation of the changes in arterial lumen, atherosclerotic plaque and arterial walls after percutaneous transluminal laser angioplasty (PTLA) in peripheral arteries. Seventeen procedures using an argon laser angioplasty system (LASTAC system II) were performed in 13 patients with totally occluded lesions in the superficial femoral and iliac arteries. During or immediately after PTLA, a 30 MHz intravascular ultrasound catheter was inserted into the channel created by laser irradiation and adjunctive balloon dilatation. The outcome of PTLA was considered morphologically successful if the residual stenosis measured by intravascular ultrasound was 75% or less. Intravascular ultrasound showed eccentric plaques in 12 (71%), calcified plaques in 11 (65%), intraluminal thrombi in 2 (12%) and arterial wall injuries in 13 (76%) of the 17 lesions. PTLA was successful in 13 lesions and failed in 4. Occurrence of arterial dissections (38%) and mean residual stenoses (44 +/- 13%) were significantly (p < 0.05) lower in successful PTLA than in unsuccessful PTLA (100%, 89 +/- 3%). Eccentric stenoses, calcified plaques and arterial wall injuries were associated with poor success. Intravascular ultrasound detection of eccentric stenoses (71%), calcified plaques (65%) and arterial wall injuries (76%) was better than by angiography (29, 29, 47%). However, no significant correlation between intravascular ultrasound and angiographic findings could be found in quantitative estimation of the residual stenoses. Intraluminal thrombi were identified only by intravascular ultrasound. Angiography showed abnormalities in five (83%) of six lesions with medial injuries demonstrated by intravascular ultrasound, but none of the seven lesions with intimal injury. Intravascular ultrasound provides accurate diagnosis of eccentric stenosis, calcification, and arterial wall injury, and can quantitatively estimate residual stenosis and arterial wall injury during and immediately after PTLA in peripheral artery disease.

Aged↗
PubMedDate not supplied

Effects of intraaortic balloon pumping on portal venous flow. Assessment with color Doppler echography.

The effects of intraaortic balloon pumping (IABP) on portal venous flow were assessed using color Doppler echography. A total of 23 heart failure patients treated with IABP were assessed. Balloon inflation was timed to occur with every other cardiac contraction. The maximum, minimum, and mean flow velocity (Vmax, Vmin and Vmean, respectively) in the right portal vein were measured with the IABP ON and OFF, and the values compared. The Vmin with IABP ON and OFF was the same (11 +/- 5 cm/sec), whereas the difference between Vmax and Vmean was small for each patient. The velocities measured with IABP ON were larger than or equal to those with IABP OFF in all cases, however, except one. Thus, Vmax (22 +/- 8 cm/sec) and Vmean (17 +/- 6 cm/sec) with IABP ON were significantly larger (p 0.01) than those with IABP OFF (20 +/- 7 cm/sec and 16 +/- 6 cm/sec, respectively). The flow pattern of the portal vein was characteristically pulsatile either with IABP ON or OFF in most cases.

Adult↗