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D C Fisher

Publications and source records attributed to D C Fisher.

46 records · Page 3Linked to original sources
PubMed1984

A pulsed Doppler echocardiographic method for calculating pulmonary and systemic blood flow in atrial level shunts: validation studies in animals and initial human experience.

The purpose of this study was to assess the accuracy of a quantitative two-dimensional range-gated Doppler echocardiographic method for estimating systemic and pulmonary flows in an open-chest canine preparation with a variable-sized atrial level shunt mimicking an atrial septal defect. In addition, we also report our initial experience with 10 children who had isolated atrial septal defects and who had pulmonary and systemic flow rations (QP:QS) determined by Doppler echocardiography simultaneously with green dye-shunt calculations in the cardiac catheterization laboratory. Ten mongrel dogs weighing 20 to 30 kg were anesthetized, intubated, and mechanically ventilated. Previously calibrated electromagnetic flow probes were placed around the ascending aorta and main pulmonary artery, and an atrial level shunt was created by inserting one-half inch diameter cannulae into the left and right atrial appendages and connecting both cannulae to 3/4 inch tubing that passed through a previously calibrated extracorporeal mechanical roller pump. This permitted quantitation as well as regulation of shunt size and direction. With each step-by-step variation in shunt magnitude, systemic and pulmonary flows were estimated by Doppler echocardiography and were matched to the simultaneous electromagnetic flowmeter recordings. Doppler-estimated systemic blood flow was obtained by imaging and recording Doppler flow velocities in the ascending aorta with the transducer positioned directly over the vessel. Doppler pulmonary flow was obtained by imaging the main pulmonary artery on the short-axis view and by determining flow velocity with the sample volume placed distal to the pulmonic valve.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

Bilateral vasoconstrictive differences and body focus.

Body focus as a function of an S's cognitive schema has been shown to be associated with bilateral differences in skin conductance. This relationship between body focus and physiological activity has been extended by other investigations studying Raynaud's patients to include bilateral differences in digital temperature. The purpose of the present study was to determine whether these results generalize to a population of normal Ss. Differential digital finger temperatures were recorded for 28 male and 28 female Ss. An association was not found between body focus and bilateral digital temperature differences in the normal Ss. It is concluded that the previous relationship found was the result of the Raynaud's disease or the body focus of a Raynaud's victim.

Adolescent↗
PubMed1983

The effect of variations of pulsed Doppler sampling site on calculation of cardiac output: an experimental study in open-chest dogs.

We measured aortic flow by two-dimensional Doppler echocardiography in an open-chest dog model to examine how variations in Doppler sample volume length and position influence aortic hemodynamic flow calculations. Fourteen dogs underwent right-heart bypass, in which venous return from the venae cavae drained by gravity to a reservoir. A variable-speed roller pump returned the blood to the pulmonary artery, fixing left-sided cardiac input and output. Echo Doppler measurements were performed using a 3.5 MHz transducer placed directly on the aortic arch to determine internal aortic cross-sectional area. The transducer was then directed to image the aortic arch for Doppler velocity measurements and the various sampling sites were investigated. Doppler cardiac output could then be determined for each of the various sample volumes over a range of known roller pump settings. Doppler velocity was analyzed using fast Fourier transform spectral analysis. Mean velocity over the cardiac cycle was obtained by planimetry of the area under the Doppler velocity curve with a minicomputer. Doppler-derived determinations of cardiac output achieved a correlation of r = 0.98-0.99 to values obtained by the roller pump over a range of cardiac outputs from 0.75-5 l/min. The standard error of the estimate was 0.21/min. In this laminar flow model, there was no difference between the predictive accuracy of any of the sampling sites over the range of roller pump flows. Our study shows that Doppler velocity measurements can be used to quantify aortic flow over a clinically useful range and that variations of sample length and position did not produce significant differences in calculated flows.

Animals↗
PubMed1983

The mitral valve orifice method for noninvasive two-dimensional echo Doppler determinations of cardiac output.

We developed and validated a mitral valve orifice method for Doppler cardiac output determination. In 15 open-chest dogs, cardiac output was controlled and measured by a roller pump interposed between the right atrium and pulmonary artery as a right-heart bypass. Left heart flows were measured in the open-chest dog model by Doppler measurements at the mitral valve orifice and compared not only to volume flow measured by the roller pump, but to electromagnetic flow meters as well. The maximum mitral valve orifice area was measured off short-axis two-dimensional echocardiographic views by planimetry. The maximal orifice was then adjusted for its diastolic variation in size by calculating a ratio of mean-to-maximal mitral valve separation on a derived M-mode echocardiogram. Flow was sampled parallel to mitral valve inflow in a four-chamber plane. The multiplication of mean flow throughout the cardiac cycle by the mean mitral valve area after correction for diastolic size variation yielded a cardiac output determination that could be compared to the roller pump measurement. Fifty-two cardiac output determinations over roller pump values of 1-5 l/min yielded a high correlation between roller pump flows and Doppler (r = 0.97 +/- 0.23 l/min). Our study shows that the mitral valve orifice provides an accurate site for Doppler cardiac output measurements.

Animals↗
PubMedDate not supplied

A comparison of digital and analog methods of Doppler spectral analysis for quantifying flow.

Ultrasonic methods can be used for calculating flow when the mean Doppler frequency is representative of spatial average velocity. We have examined the capabilities of two commercially available methods of Doppler spectral analysis for providing measurements of spatial average velocity and flow. In a steady state flow model, Doppler audio spectra were recorded using a 5-MHz duplex scanner. Fast Fourier transform (FFT) spectral analysis was used to determine mean (M), mode (MO), and maximum (MAX) frequencies. An analog method (offset zero crossing detector = ZC) was used to determine root mean square (RMS) frequencies. The results of comparing Doppler flow estimates (QM, QMO, QMAX and QRMS) with direct flow measurements (n = 10; range = 128-1098 ml/min) were (1) QM = 0.67Q + 23 ml/min (SEE = 36 ml/min); (2) QMO = 0.96Q + 152 ml/min (SEE = 32 ml/min); (3) QMAX = 1.19Q + 171 ml/min (SEE = 23 ml/min); and (4) QRMS = 0.93Q + 76ml/min (SEE = 92 ml/min). Estimates of flow using M and RMS frequencies were adversely affected by experimental conditions likely to result in turbulence. We conclude that application of commercially available FFT determined M frequencies could result in significant errors in calculations of spatial average velocity and flow. Alternatively, FFT determined MO frequencies and ZC determined RMS frequencies resulted in accurate estimates of flow in this model. This study demonstrates the importance of evaluating the capabilities of commercially available methods of Doppler spectral analysis when using ultrasound for determining velocity and flow.

Blood Flow Velocity↗
PubMedDate not supplied

CD20-directed antibody-mediated immunotherapy induces responses and facilitates hematologic recovery in patients with Waldenstrom's macroglobulinemia.

Waldenstrom's macroglobulinemia (WM, lymphoplasmacytic lymphoma) is a B-cell lymphoproliferative disorder in which CD20 is expressed on tumor cells from most patients. Several small studies have suggested a benefit from the anti-CD20 monoclonal antibody rituximab (Rituxan, MabThera) in patients with WM. In this retrospective study, we examined the outcome of 30 previously unreported patients with WM who received treatment with single-agent rituximab (median age 60; range 32-83 years old). The median number of prior treatments for these patients was 1 (range 0-6), and 14 patients (47%) received a nucleoside analogue before rituximab therapy. Patients received a median of 4.0 (1-11.3) infusions of rituximab (375 mg/m2). Three patients received steroids with their infusions for prophylaxis of rituximab-related infusion syndrome. Overall, treatment was well tolerated. Median immunoglobulin M (IgM) levels for all patients declined from 2,403 mg/dL (range 720-7639 mg/dL) to 1,525 mg/dL (range 177-5,063 mg/dL) after rituximab therapy (p = 0.001), with 8 of 30 (27%) and 18 of 30 (60%) patients demonstrating >50% and >25% decline in IgM, respectively. Median bone marrow lymphoplasmacytic (BM LPC) cell involvement declined from 60% (range 5-90%) to 15% (range 0-80%) for 17 patients for whom pre- and post-BM biopsies were performed (p < 0.001). Moreover, 19 of 30 (63%) and 15 of 30 (50%) patients had an increase in their hematocrit (HCT) and platelet (PLT) counts, respectively. Before rituximab therapy, 7 of 30 (23.3%) patients were either transfusion or erythropoietin dependent, whereas only 1/30 (3.3%) patients required transfusions (no erythropoietin) after rituximab. Overall responses after treatment with rituximab were as follows: 8 (27%) and 10 (33%) of the patients achieved a partial (PR) and a minor (MR) response, respectively, and an additional 9 (30%) of patients demonstrated stable disease (SD). No patients attained a complete response. The median time to treatment failure for responding (PR and MR) patients was 8.0 months (mean 8.4: range 3-20+ months), and 5.0 months (mean 6.1; range 3-12+ months) for patients with SD. These studies therefore demonstrate that rituximab is an active agent in WM. Marked increases in HCT and PLT counts were noted for most patients, including patients with WM who had MR or SD. A prospective clinical trial to more completely define the benefit of single-agent rituximab in patients with WM has been initiated by many of our centers.

Adult↗
PubMedDate not supplied

Changes in health-related quality of life and depression in heart transplant recipients.

BACKGROUND: The intent of this study was to measure health-related quality of life and depression in 94 heart transplant recipients. METHODS: Changes in health-related quality of life and depression were examined by administering the Sickness Impact Profile and the Beck Depression Inventory before heart transplantation, as well as 4, 8, 12, 24, 36, 48, and 60 months after surgery. RESULTS: Sickness Impact Profile scores obtained before heart transplantation highlighted the greatest health-related quality of life dysfunction in work, sleep and rest, home management, and recreation and pastimes. Posttransplantation measures suggested improvement (p < 0.05) in emotional behavior, home management, mobility, ambulation, depression, eating behavior, social interaction, body care and movement, sleep and rest, recreation and pastimes, depression, and physical, overall, and psychosocial functioning. Continued improvement was noted up to 5 years after transplantation although patients continued to have marked work-related dysfunction. Age, medication regimen, rejection episodes, and a variety of preoperative medical variables were not related to health-related quality of life. Actuarial survival rates at 1, 2, 3, 4, and 5 years were 89%, 87%, 80%, 79%, and 79%, respectively. CONCLUSIONS: Our results suggest that as early as 4 months after heart transplantation, patients show excellent functioning in most health-related quality of life areas. Survival rates are encouraging. Patients did not generally experience problems with depression within the first 4 months after heart transplantation. Notable problems remain after transplantation in rate of return to work where only 53% returned to work by 5 years after heart transplantation.

Actuarial Analysis↗