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Biomedical subjects

C L Reid

Publications and source records attributed to C L Reid.

At least 19 recordsLinked to original sources
PubMed2001

Simple method for estimating regurgitant volume with use of a single radius for measuring proximal isovelocity surface area: an in vitro study of simulated mitral regurgitation.

The proximal isovelocity surface area (PISA) color Doppler method with use of a hemielliptic formula is reported to be accurate for quantitating regurgitant volume (RV). However, this formula ideally requires the measurement of 2 or 3 radii and therefore is not widely used clinically. The purpose of this in vitro study was to derive a simple PISA formula for estimating RV with use of a single radius axial to the valve orifice and to compare it with the clinically used single-radius hemispherical formula (2 x pi R(2) x AV x TVI/Vp), where AV is the apparent color Doppler aliasing velocity, R is the PISA color Doppler aliasing radius, TVI is time-velocity integral of the jet by continuous wave Doppler, and Vp is the peak velocity of the jet by continuous wave Doppler. Pulsatile flow studies were performed across a convex curvilinear surface, which more closely approximates the shape of the mitral valve than does a planar surface. Pulse rates (60 to 80 bpm), peak flow velocities (4.0 to 6.0 m/s), and regurgitant orifice areas (0.2 to 1.0 cm(2)) were varied to simulate mitral regurgitation. The AVs were varied from 11 to 39 cm/s, and a single PISA aliasing radius was measured at each AV. Excellent linear correlations were obtained between the PISA radius and the actual RV measured with use of a beaker (r = 0.94 to 0.97, P <.0001). A series of simplified formulas was derived from the regression line of the PISA radius versus the RV. For example, with an AV of 21 cm/s, RV was estimated by a simplified PISA formula (where RV[mL] = 10 x R [mm] - 30) with an accuracy of 3.3 +/- 6.3 mL versus -20.3 +/- 8.7 mL for the standard single-radius PISA method (P <.0001). By using the standard single-radius hemispherical PISA formula, RV was underestimated if the radius was <20 mm. By using simplified regression equations, the PISA radius accurately estimated RV at a PISA radius <20 mm. Clinical studies are necessary to validate this concept.

Echocardiography, Doppler, Color↗
PubMed2001

A cross marks the spot: a study of roadside death memorials in Texas and Oklahoma.

Motor vehicle collisions (MVCs) resulting in death have been a serious concern for many years. However, the placement of roadside death memorials (RDMs) at collision sites has become increasingly common in the United States, in the memorialization of those deceased because of MVCs. This practice has been used in numerous countries for hundreds of years. Of the 78 sites observed, most were for males whose deaths had occurred in the past year and were placed by both family members and friends. The sites include the use of a cross and flowers whose meaning is obvious; however numerous other artifacts are found, the meaning of which is less obvious. Some of the functions served by these memorials are to prolong the memory of the deceased in a public place and to communicate with the deceased and to society. RDMs are used by mourners as a way of coping with the sudden and tragic nature of deaths from MVCs.

Accidents, Traffic↗
PubMed2000

Valvular abnormalities and cardiovascular status following exposure to dexfenfluramine or phentermine/fenfluramine.

CONTEXT: Fenfluramine and dexfenfluramine were voluntarily withdrawn from the market in September 1997 because of reports of an association with heart valve abnormalities. Studies have been limited by lack of comparison with untreated controls. OBJECTIVE: To evaluate cardiovascular status and the prevalence of valvular abnormalities, as assessed by clinical cardiovascular parameters and echocardiography, in patients treated for obesity with dexfenfluramine or phentermine/fenfluramine. DESIGN: Reader-blinded controlled study completed in February 1998. SETTING AND PARTICIPANTS: Twenty-five clinical centers in the United States. Of 1640 enrolled subjects, 1473 were eligible (479 and 455 had taken dexfenfluramine and phentermine/fenfluramine, respectively, continuously for 30 days or more in the previous 14 months, and 539 were untreated matched controls) and provided clinical and echocardiographic data. Mean (SD) age was 47.4 (11.4) years, mean body mass index was 35.0 (7.4) kg/m2, and 74% were women. Mean (SD) duration of therapy was 6.0 (3.3) months (range, 1-18.4 months) in the dexfenfluramine group, and 11.9 (10.4) months (range, 1.4-63 months) in the phentermine/fenfluramine group, while the untreated group had no anorexigen use during the previous 5 years. MAIN OUTCOME MEASURES: Cardiovascular signs and symptoms; echocardiographic evidence of aortic (AR) or mitral (MR) regurgitation according to US Food and Drug Administration (FDA) criteria (AR > or = mild or MR > or = moderate) and by grade; tricuspid and pulmonic valve regurgitation; and aortic, mitral, and tricuspid valve leaflet mobility and thickness, for treated vs untreated subjects. RESULTS: Cardiovascular signs and symptoms were similar among anorexigen-treated and untreated subjects. Prevalence rates and relative risk (RR) of AR were significantly increased in anorexigen-treated patients and were 8.9% in the dexfenfluramine group (RR, 2.18; 95% confidence interval [CI], 1.32-3.59), 13.7% in the phentermine/fenfluramine group (RR, 3.34; 95% CI, 2.09-5.35), and 4.1% in the untreated group (P<.001). No statistically significant differences in prevalence were observed for MR, thickening or decreased mobility of any valve leaflet, calculated pulmonary artery systolic pressure, or left ventricular ejection fraction. Serious cardiac events (including myocardial infarction, congestive heart failure, or ventricular arrhythmia) occurring at any time were not statistically different in treated and untreated subjects (dexfenfluramine, 9.0%; phentermine/fenfluramine, 4.0%; and untreated, 8.4%); and following anorexigen treatment were uncommon (dexfenfluramine, 2.3%; phentermine/fenfluramine, 2.4%, and untreated, 3.3%, when adjusted for the median start date of anorexigen use). CONCLUSIONS: Our data indicate that use of dexfenfluramine and phentermine/fenfluramine is associated with an increase in the prevalence of AR using FDA echocardiographic criteria, but was not associated with an increase in the prevalence of MR using FDA criteria or with serious cardiac events.

Aortic Valve Insufficiency↗
PubMed1998

Indirect calorimetry--a review of recent clinical applications.

There has been a resurgence of interest in the information provided by indirect calorimetry. In the past calorimetry was considered a research technique, but technological advances have made it applicable in many clinical situations. Recent clinical applications of this technique have been examined in this review.

Acquired Immunodeficiency Syndrome↗
PubMed1997

Safety and results of dobutamine stress echocardiography in women versus men and in patients older and younger than 75 years of age.

The purpose of this retrospective study was to examine 732 consecutive patients who underwent dobutamine stress echocardiography (DSE) in order to compare the safety and result profiles of this test between women versus men and in patients > or = 75 and < 75 years of age. Our study included 416 women (57%) and 316 men (43%; mean age 62 +/- 12 years [range 16 to 93]). Patients were divided into 3 age groups: (1) group I (n = 179): < 55 years (mean 47 +/- 6), (2) group II (n = 447): 55 to 74 years (mean 64 +/- 5), and (3) group III (n = 106): > or = 75 years (mean 80 +/- 4). DSE was more likely to have negative results in women than in men (prevalence of positivity = 20% vs 31%, p = 0.001), but DSE had a similar safety profile in both genders. Women required lower doses of dobutamine and atropine to reach an end point. There was a similar incidence of test positivity in older and younger patients (23% in group I, 24% in group II, and 30% in group III, p = NS). DSE was generally a safe test in patients > or = 75 years, but there was a different safety profile in the elderly group compared with younger patients--specifically, more frequent asymptomatic hypotension (7% in group I, 13% in group II, and 25% in group III, p = 0.0002) and ventricular arrhythmias (26% in group I, 30% in group II, and 41% in group III, p = 0.04), but less frequent chest pain (32% in group I, 23% in group II, and 17% in group III, p = 0.009). Multivariate analysis suggested that the baseline usage of beta blockers was also a major determinant of the safety and ischemia profile during DSE. In conclusion, there were significant gender- and/or age-specific differences in the safety and test result profile of DSE. These differences should be considered when performing or interpreting DSE, particularly in women and in patients aged > or = 75 years.

Adolescent↗
PubMed1997

Usefulness of color Doppler proximal isovelocity surface area method in quantitating valvular regurgitation.

To define the clinical utility of the color Doppler proximal isovelocity surface area (PISA) method for estimating regurgitant stroke volume (SV), 160 regurgitant lesions were evaluated in 104 patients with mitral (MR), aortic (AR), and tricuspid (TR) regurgitation. Regurgitant SV by PISA was calculated as 2 pi R2 x V x (time-velocity integral/peak flow velocity), where R is the radius corresponding to the first blue-red interface velocity of the maximal PISA during the cardiac cycle. The time-velocity integral and peak flow velocity from the continuous-wave Doppler recording of the regurgitant jet were used to correct PISA for phasic variations in regurgitant flow. Fifteen lesions were excluded because of difficulty in tracing the continuous-wave Doppler regurgitant curve. Among 145 remaining regurgitant lesions, PISA was measurable in 50 (78%) of 64 cases of MR and 24 (69%) of 35 cases of TR but in only 12 (26%) of 46 cases of AR (p < 0.001). Regurgitant SV by PISA correlated modestly well with jet area/atrial area in all atrioventricular valve lesions (MR: r = 0.55; TR: r = 0.65; p < 0.001). However, the correlation improved if only central jets were considered (MR: r = 0.70; TR; r = 0.75; p < 0.001). These findings are not unexpected because jet area/atrial area underestimates the true severity of regurgitation in cases of eccentric (wall-impinging) jets. PISA was detected in all severe cases of regurgitation but in only 64% of cases of mild MR, 45% of cases of mild TR, and 6% of cases of mild AR (p < 0.01). The color Doppler PISA method is clinically useful in estimating regurgitant SV in MR and TR, including mild cases, but is less useful in AR.

Adolescent↗
PubMed1997

Phase IB clinical trial of the oligosaccharide processing inhibitor swainsonine in patients with advanced malignancies.

The indolizidine alkaloid swainsonine, a potent inhibitor of Golgi alpha-mannosidase II, has been shown to reduce tumor cell metastasis, enhance cellular immune responses, and reduce solid tumor growth in mice. In our previous Phase I study, swainsonine administered by 5-day continuous infusion inhibited L-phytohemagglutinin-reactive N-linked oligosaccharide expression on peripheral blood lymphocytes. Significant toxicities included edema and elevated serum aspartate aminotransferase (AST). One patient with head and neck cancer had objective (>50%) tumor remission. Two patients showed symptomatic improvement. The objectives of this Phase IB trial were to examine the pharmacokinetics, toxicities, and biochemical effects of bi-weekly oral swainsonine at escalating dose levels (50-600 microgram/kg) in 16 patients with advanced malignancies and 2 HIV-positive patients unsuitable for conventional therapy. Eastern Cooperative Oncology Group performance status was </=2. The maximum tolerated dose was defined as 300 microgram/kg/day due primarily to serum AST abnormalities and dyspnea. Other adverse events present in >20% of patients included increase in serum AST (all patients), fatigue (n = 9), anorexia (n = 6), dyspnea (n = 6), and abdominal pain (n = 4). Inhibition of Golgi alpha-mannosidase II occurred in a dose-dependent manner. Examination of immunological parameters revealed a transient decrease in CD25(+) peripheral blood lymphocytes and, in seven of eight patients, an increase in CD4(+):CD8(+) ratios at 2 weeks. Serum drug levels peaked 3-4 h following a single oral dose in most patients and were proportional to dose at levels >/=150 microgram/kg. We conclude that oral swainsonine is tolerated by chronic intermittent administration at doses up to 150 microgram/kg/day. Adverse events considered drug related were similar to those observed in the infusional study but with fatigue and neurological effects also noted. Investigations of alternative dosing schedules with low starting doses are suggested for further clinical testing.

Adult↗
PubMed1996

Left ventricular cavitary geometry and dynamic intracavitary left ventricular obstruction during dobutamine stress echocardiography.

To investigate the relationship between left ventricular cavity geometry and dynamic intracavitary left ventricular obstruction occurring during dobutamine stress echocardiography, we evaluated 44 patients who underwent dobutamine stress echocardiography. Dynamic intracavitary left ventricular obstruction appeared in 10 (23%) patients (Group 1), and was absent in the remaining 34 patients (Group 2), during dobutamine stress echocardiography. The ratio of the apicalto-narrowest mid-left ventricular minor-axis dimension (D1/D2), as an index of the left ventricular cavitary geometry, was measured in the baseline two dimensional apical long-axis view. The left ventricular out-flow blood Doppler velocity was measured in the apical long-axis or five-chamber view at each stage during dobutamine infusion. Left ventricular end-systolic dimension was smaller (21 +/- 4 mm v 29 +/- 6 mm; p< .01), percent fractional shortening of the left ventricle was greater (51 +/- 4% v 39 +/- 8%, P>.01), and D1/D2 was greater (1.13 +/- 0.08 v.0.96 +/- 0.09; p < .0001) in Group 1 than in Group 2 in the baseline echocardiogram. Maximal out flow blood Doppler velocity during dobutamine infusion correlated moderately with percent fractional shortening of the left ventricle (r = .53; P < .01) and D1/D2 (r = .60; P < .0001). Dynamic intracavitary left ventricular obstruction, defined as an elevated intracavitary Doppler flow velocity with late-systolic peaking, was not related to the presence of left ventricular hypertrophy or the development of hypotension during dobutamine infusion. We conclude that dynamic left ventricular intracavitary obstruction during dobutamine infusion is associated with a characteristic (narrower-waisted) left ventricular cavitary geometry and increased contractility.

Adult↗
PubMed1995

Gender differences in left ventricle geometry and function in patients undergoing balloon dilatation of the aortic valve for isolated aortic stenosis. NHLBI Balloon Valvuloplasty Registry.

BACKGROUND: Gender differences in cardiac size have been described in normal humans and animals and in response to pressure overload. To examine the influence of gender on the left ventricular response to pressure overload, clinical, haemodynamic, and echocardiographic data were analysed in the 232 adults with isolated aortic stenosis enrolled in the Balloon Valvuloplasty Registry. METHODS AND RESULTS: There were 92 men (mean (SD) age 75 (11) years) and 140 women (79 (9) years; P = 0.002). Women had similar symptoms (New York Heart Association class) but lower overall functional status than men (P = 0.008). Catheterisation data showed similar valve area indices (mean (SD) (0.30 (0.09) in men and 0.31 (0.13) cm/m2 in women) but higher peak and mean gradients in women (peak 74 (30) v 63 (22) mm Hg; mean 61 (21) v 54 (18) mm Hg; both P < or = 0.01). On M mode echocardiography women had greater septal and posterior wall thickness but similar cavity diameter, after normalising dimensions to body surface area, resulting in higher relative wall thickness (0.60 (0.20) v 0.50 (0.15); P = 0.0002). Left ventricular mass index was similar in women and men (166 (59) v 159 (50) gm/m2 respectively), however, the prevalence of left ventricular hypertrophy according to sex specific criteria was 54% in men and 81% in women (P = 0.0001). Multiple logistic regression models that adjusted for age, functional status, fractional shortening, and left ventricular systolic pressure found the presence or absence of hypertrophy to be independently associated with gender (P < or = 0.002). Left ventricular systolic function tended to be better in women, who had a higher cardiac index (2.5 (0.8) v 2.3 (0.6) 1/min/m2; P = 0.01), left ventricular peak systolic pressure (211 (36) v 192 (35) mm Hg; P = 0.0001), and echo fractional shortening (32 (13) v 28 (12)%; P = 0.05); however, these differences were reduced when patients with regional wall motion abnormalities were excluded. CONCLUSIONS: In this population of elderly patients undergoing balloon dilatation of isolated aortic stenosis, left ventricular chamber geometry was different in men and women. Because this was a selected population, gender should be further evaluated as a possible determinant of the cardiac adaptation to chronic pressure overload.

Aged↗
PubMed1992

Influence of mitral valve morphology on mitral balloon commissurotomy: immediate and six-month results from the NHLBI Balloon Valvuloplasty Registry.

Echocardiographic data were analyzed in 555 patients undergoing mitral balloon commissurotomy (MBC). Patients were enrolled in the National Heart, Lung, and Blood Institute Balloon Valvuloplasty Registry from 24 centers. There were 456 women and 99 men with a mean age of 54 years. Before MBC the two-dimensional echocardiographic variables of mitral valve thickness, mobility, calcification, and subvalvular disease were evaluated and assigned scores of 1 to 4. The mitral valve morphology score was related to mitral valve area (MVA) measured after MBC by cardiac catheterization. The leaflet mobility score was related to the immediate post-MBC MVA: 2.2 +/- 0.8 cm2 for grade 1, 1.9 +/- 0.7 cm2 for grade 2, 1.7 +/- 0.7 cm2 for grade 3, and 1.9 +/- 0.9 cm2 for grade 4 (p less than 0.001). Results of the MVA after MBC showed a similar relationship for each echocardiographic variable. The total morphology score (sum of the four variables) showed a weak relationship to MVA immediately after MBC (r = 0.24), which was persistent at 6 months after MBC (r = -0.25). Multiple regression analysis showed that the MVA after MBC is predicted by pre-MBC MVA (p less than 0.001), left atrial size (p = 0.01), balloon diameter (p = 0.02), cardiac output (p = 0.004), and leaflet mobility (p = 0.01). The R2 of the model was 0.31 (p less than 0.001). Total morphology score, leaflet thickness, calcification, and subvalvular disease were not important univariate or multivariate predictors of the results of MBC.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Response of angina and ischemia to long-term treatment in patients with chronic stable angina: a double-blind randomized individualized dosing trial of nifedipine, propranolol and their combination.

Seventy-four patients with chronic stable mild angina, mild coronary artery disease (83% had one- or two-vessel disease) and normal left ventricular function were studied to measure the response of treadmill exercise performance and painful and silent ischemia in the ambulatory setting to randomly assigned treatment with nifedipine or propranolol and their combination; titration to maximal tolerated dosages was performed in double-blind manner. At 3 months both nifedipine and propranolol reduced the weekly angina rate (p less than 0.05); during treadmill exercise testing, increases (p less than 0.05) were noted in time to angina and total exercise time and decreases in maximal ST depression at the end of exercise. There were no differences between the responses to nifedipine and propranolol and no significant additional changes were seen after another 3 months of therapy. The combination of nifedipine and propranolol reduced the number of patients with angina on exercise treadmill testing from 64% to 38% (p less than 0.05). During ambulatory electrocardiographic monitoring before treatment, there were 1.4 +/- 2.4 (mean +/- SD) episodes/24 h of painful ischemia and a very low silent ischemia frequency: mean 1.1 +/- 2.7 episodes/24 h, mean duration 16 +/- 25 min/24 h. Treatment with propranolol and nifedipine resulted in reduction of episodes and duration of painful and painless ischemia; approximately 77% of patients were free of all ischemic episodes. It is concluded that patients with chronic stable mild angina have a low incidence of silent ischemia. Nifedipine or propranolol alone, titrated to individualized maximally tolerated dosages, are equally effective in long-term control of painful and painless ischemia, anginal episodes and exercise-induced ischemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Angina Pectoris↗
PubMed1991

The role of echocardiography/Doppler in catheter balloon treatment of adults with aortic and mitral stenosis.

Doppler and two-dimensional echocardiography (2DE) have played a major role in the evaluation of patients undergoing catheter balloon treatment of aortic and mitral stenosis. Doppler/2DE has made possible an understanding of the mechanism of increase in valve area. Before the procedure, Doppler/2DE provides a reasonable estimate of the severity of the valvular stenosis and associated cardiac abnormalities. The evaluation of mitral valve morphology by 2DE before catheter balloon treatment has shown that patients with excellent leaflet motion and minimal increase in valve thickness have the greatest increase in mitral valve area. During the procedure, Doppler/2DE can aid in the transseptal puncture, in positioning the balloons across the stenotic orifice, and in the immediate assessment of changes in valve function and complications. The estimate of the aortic and mitral valve gradients and areas by Doppler/2DE before catheter balloon treatment shows a reasonable correlation with hemodynamic measurements. Immediately after the procedure, the Doppler/2DE estimates of aortic valve gradient and area show a fair correlation with data from cardiac catheterization, provided care is taken to avoid technical problems. Doppler/2DE assessment of mitral valve area immediately after catheter balloon commissurotomy (CBC) shows a poor correlation with catheterization data, which has been attributed to rapid changes in left atrial compliance and gradient. However, the correlation of Doppler estimates of mitral valve area with catheterization data improves at 3 months after CBC. Serial evaluations of patients after aortic or mitral catheter balloon dilatation should permit detection of restenosis and valve regurgitation and assessment of ventricular function and may provide valuable insights into the mechanisms of restenosis and changing clinical status.

Adult↗