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Biomedical subjects

T M Bashore

Publications and source records attributed to T M Bashore.

At least 127 records · Page 7Linked to original sources
PubMed1989

Cardiovascular and renal toxicity of a nonionic radiographic contrast agent after cardiac catheterization. A prospective trial.

STUDY OBJECTIVE: To determine the incidence of cardiovascular and renal toxicity of a nonionic contrast agent when used for cardiac catheterization, and to assess the value of electrolytes and urinalysis results as predictors of nephropathy induced by a contrast agent. STUDY DESIGN: Nonrandomized trial using a criterion standard and a cohort analytic study with a 48-hour follow-up. SETTING: Referral-based university hospital. PATIENTS: Convenience sample of patients having diagnostic cardiac catheterization. Renal function and clinical status were evaluated at baseline in 1,144 patients; at 24 hours in 1,077 (94%); and at 48 hours in 663 (57%). INTERVENTIONS: After patients received saline for hydration, coronary angiography and left ventriculography were done with iopamidol (average dose, 203 +/- 56 cc). MEASUREMENTS AND MAIN RESULTS: The definite and possible incidence of major acute cardiovascular complications from nonionic contrast media was 0.2% and 0.7%, respectively. The mean serum creatinine level increased 11.5 mumol/L from baseline at 24 hours (P less than 0.0001) and 16.8 mumol/L from baseline at 48 hours (P less than 0.0001). Results in a randomly selected training sample were studied to determine predictors of a rise in serum creatinine of 44.2 mumol/L or more. The baseline serum creatinine level and age were significant predictors of renal injury, but hypertension, diabetes mellitus, congestive heart failure, vascular disease, the volume of contrast agent injected or baseline values of urinary variables did not predict nephrotoxicity. In an independent validation sample, only the baseline serum creatinine level was confirmed as a predictor of nephrotoxicity, whereas age was not. A model that predicted contrast-induced nephropathy by the serum creatinine level showed an exponential increase in the risk for nephrotoxicity if the baseline level was 106.1 mumol/L or higher. CONCLUSIONS: Patients have a small but significant rise in serum creatinine after cardiac catheterization with a nonionic contrast agent. Baseline renal insufficiency is the only confirmed predictor of nonionic contrast-induced nephrotoxicity.

Aged↗
PubMed1989

Validation of pressure-volume data obtained in patients by initial transit radionuclide angiocardiography.

In order to validate the measurement of pressure-volume loops and stroke work in humans, simultaneous digital subtraction ventriculography (DSA) and first-pass radionuclide angiocardiography (RNA) coupled with high-fidelity micromanometer left ventricular pressure measurements were undertaken in 34 patients, mean age 75 +/- 9 years, with aortic stenosis. Twenty-nine patients had a repeat study after balloon valvuloplasty, for a total of 63 DSA and RNA pressure-volume loops. All data were analyzed in a systemic fashion in order to minimize intra- and interobserver error. Linear regression analysis was used to calculate the degree of agreement between the two technologies. Left ventricular ejection fraction (RNA: 0.47 +/- 0.17, DSA: 0.49 +/- 0.18) had a correlation coefficient of 0.96; left ventricular end-diastolic volume (RNA: 171 +/- 42 ml, DAS: 168 +/- 52 ml) and end-systolic volume (RNA: 95 +/- 50 ml, DSA: 89 +/- 50 ml) had correlation coefficients of 0.89 and 0.95, respectively. Left ventricular stroke volume (RNA: 75 +/- 26 ml, DSA: 75 +/- 27 ml) had a correlation coefficient of 0.92, while integrated pressure-volume loop or stroke work (RNA: 15.6 +/- 6.6 ergs 10(6), DSA: 15.9 +/- 6.3 ergs 10(6] had a correlation coefficient of 0.89. These data demonstrate that RNA measurements of left ventricular chamber dynamics concur with that obtained with DSA. With semiautomated data analysis, the portable first-pass RNA pressure-volume data are also less labor-intensive. Moreover, multiple measurements of ventricular performance during hemodynamic manipulations in the catheterization laboratory or operating room would allow for a more precise estimation of left ventricular performance.

Aged↗
PubMed1989

Analysis of the early rise in aortic transvalvular gradient after aortic valvuloplasty.

The relationship between dynamic changes in aortic valve gradient and left ventricular ejection performance in the early period after successful percutaneous aortic valvuloplasty has not been described in detail. Accordingly 20 adult patients with severe symptomatic calcific aortic stenosis underwent first-pass radionuclide angiography and Doppler echocardiography before, immediately after, and 2 to 4 days after the valvuloplasty procedure. A significant (p less than 0.001) reduction in peak-to-peak (72 +/- 24 mm Hg to 36 +/- 11 mmHg) and mean (60 +/- 20 mm Hg to 34 +/- 9 mm Hg) transaortic gradient and an increase in aortic valve area (0.5 +/- 0.2 cm2 to 0.8 +/- 0.2 cm2) were measured by high-fidelity micromanometer catheters immediately after aortic valvuloplasty. Results of Doppler echocardiography showed a significant (p less than 0.001) immediate decrease in peak instantaneous (81 +/- 22 mm Hg to 53 +/- 15 mm Hg) and mean (48 +/- 14 mm Hg to 31 +/- 9 mm Hg) aortic gradients. However, 2 to 4 days later a significant (p less than 0.001) return of peak (56 +/- 15 mm Hg to 65 +/- 20 mm Hg) and mean (31 +/- 9 mm Hg to 39 +/- 12 mm Hg) transvalvular gradient occurred. Aortic valve area as determined by the continuity equation also increased from 0.4 +/- 0.2 cm2 to 0.6 +/- 0.2 cm2 immediately after the procedure (p less than 0.001), then partially returned to baseline (0.5 +/- 0.2 cm2; p less than 0.005) at 2 to 4 days.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1989

Functional abnormalities in isolated left bundle branch block. The effect of interventricular asynchrony.

Eighteen patients with isolated left bundle branch block (LBBB) were compared with 10 normal control subjects. Apexcardiograms, phonocardiograms, electrocardiograms, two-dimensional and dual M-mode echocardiograms, and radionuclide ventriculograms (RNV) were performed. There were no differences in the timing of right ventricular events between LBBB and normal subjects; however, striking delays in left ventricular systolic and diastolic events were apparent in the LBBB group. The delay was associated with shortening of left ventricular diastole and resultant increase in the ratio of right to left ventricular diastolic time in LBBB (1.2 +/- 0.08) compared with normal (1.0 +/- 0.06), p less than 0.0001. First heart sound (S1) amplitude, expressed as the ratio S1/S2, was decreased in LBBB compared with normal (0.67 +/- 0.2 compared with 1.34 +/- 0.25, p less than 0.01), in part due to wide separation of the valvular contributors to S1. The abnormal interventricular septal motion in LBBB corresponded to periods of asynchrony in contraction, ejection, end systole, and end diastole between right and left ventricles. Radionuclide ventriculograms revealed decreased regional ejection fraction of the septum in LBBB (40 +/- 16%) compared with 67 +/- 7% in normal subjects (p less than 0.001), while the apical and lateral regional ejection fractions were similar in the two groups. This loss of septal contribution resulted in a reduction in global ejection fraction in LBBB compared to normals (54 +/- 7% compared with 62 +/- 5%, p less than 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Comparison of coronary stenosis quantitation results from on-line digital and digitized cine film images.

To examine the effects of digital image acquisition mode and subtraction techniques on the results of coronary stenosis quantitation, 100 discrete lesions from 45 patients undergoing routine diagnostic angiography were analyzed in each of 3 image types: direct on-line digital, electrocardiogram-gated digital subtraction and digitized cine film images. For the geometric measurements (minimal lumen diameter and percent diameter stenosis) correlation coefficients for 2-way comparisons among the image types ranged from 0.90 to 0.96. Linear regression slopes ranged from 0.93 to 1.00, with intercepts from 0.03 to 0.07 mm for minimal diameter and -0.5 to 4.4% for percent diameter stenosis. For the videodensitometric percent area stenosis data, the correlation coefficients ranged from 0.80 to 0.89, with linear regression slopes from 0.84 to 0.89 and intercepts from 8.3 to 12.8%. Thus, the results of quantitative geometric measurements of coronary stenosis severity were not strongly affected by image acquisition mode (on-line versus cine film digitization) or by electrocardiogram-gated digital subtraction, while densitometric data correlated less well when on-line digital and digitized cine film acquisition methodology were compared.

Angiography↗
PubMed1988

Pulsus alternans induced by inferior vena caval occlusion in man.

To assess the effect of rapid preload reduction on left ventricular performance in nonischemic cardiomyopathy, 11 patients were studied during inferior vena caval (IVC) balloon occlusion. Five developed sustained pulsus alternans. During pulsus alternans, the strong beats demonstrated systolic performance characteristics similar to baseline values, despite a drop in both left ventricular (LV) end-diastolic diameter (66 +/- 13 to 61 +/- 13 mm; p less than 0.05) and LV end-diastolic pressure (21 +/- 8 to 9 +/- 6 mmHg; p less than 0.05). In contrast, the weak beats demonstrated a reduction in peak systolic pressure (130 +/- 36 to 109 +/- 33 mmHg; p less than 0.02), fractional shortening (20% +/- 4% to 17% +/- 9%; p less than 0.05) and peak positive dP/dt (1,006 +/- 224 to 921 +/- 287 mmHg; p less than 0.05). Measures of diastolic performance (peak negative dP/dt, the time constant of LV relaxation, the length of diastasis, and LV end-diastolic stress) were not different between baseline beats and the strong beats; and only LV end-diastolic stress differed when baseline beats were compared to the weak beats. When the strong beats were compared to the weak beats during induced pulsus alternans, significant differences were observed in peak systolic pressure, peak positive dP/dt, and fractional shortening, but no differences in any measured diastolic parameter was observed. A slight difference was noted in the left ventricular end-diastolic diameters, with the weak beat consistently beginning at a slightly smaller diameter (61 +/- 13; mm vs 59 +/- 13; p less than 0.05). In summary, these data are consistent with an augmentation and deletion of intrinsic contractile forces in association with an alternation in preload on a beat-to-beat basis as best describing left ventricular performance during pulsus alternans.

Blood Pressure↗
PubMed1988

Changes in epicardial coronary arterial diameter following intracoronary papaverine in man.

The effect of intracoronary papaverine administration on epicardial coronary arterial diameter was examined in 18 male patients. Coronary-artery cineangiograms were acquired with a power injector before intervention, 20 sec after intracoronary saline (control), and 20 sec after administration of papaverine into either the left (12 mg) or right (8 mg) coronary artery. Absolute coronary arterial diameter of a normal-appearing segment was quantified using a previously validated, fully automated digital edge detection program with an ADAC digital radiographic unit. Baseline coronary arterial diameter of 3.1 +/- 0.8 mm did not significantly change after saline administration (3.1 +/- 0.9 mm) but did significantly increase (p less than .001) to 3.4 +/- 0.9 mm after papaverine administration. No significant percent change in diameter occurred in either the left anterior descending (-.5 +/- 1.7%), left circumflex (-.2 +/- 1.1%), or right (-3.0 +/- 3.8%) coronary arteries with saline, but significant (p less than .001) increases occurred with papaverine (7.2 +/- 4.1%, 7.0 +/- 4.5%, 6.8 +/- 2.7%, respectively). The response of 7 coronary arteries examined immediately proximal to a significant lesion was not significantly different from the response of the remaining 11 coronary arteries. In conclusion, intracoronary papaverine causes a significant increase in coronary arterial diameter. This has clinical implications for assessing coronary flow reserve with devices that defect flow velocity.

Aged↗
PubMed1988

Postural exercise abnormalities in symptomatic patients with mitral valve prolapse.

The hemodynamics of the supine and upright exercise response in 16 symptomatic women with mitral valve prolapse (Group I) was compared with that in 8 asymptomatic normal control women (Group II). All subjects had supine and upright echocardiography and phonocardiography at rest and none demonstrated mitral regurgitation. All participants then underwent same day graded bicycle exercise, with simultaneous radionuclide angiography in both the upright and the supine posture. Catecholamines were measured, and a variety of volumetric and hemodynamic data were obtained. Group I (patients with mitral valve prolapse) demonstrated a reduced exercise tolerance, especially during upright exercise, as measured by both total exercise duration and maximal work load achieved. Mean total catecholamine measurements were similar between the two study groups at comparable mean heart rate, mean blood pressure and mean rate-pressure (double) product. No difference was observed in the ratio of right to left ventricular stroke counts at rest or during exercise regardless of posture, suggesting that exercise-induced mitral regurgitation did not occur. A difference was noted, however, in left ventricular end-diastolic volume index. At rest, Group I patients exhibited a 42% decrease in this index when sitting upright, and this difference from supine values persisted at submaximal (300 kpm/min) and peak work loads (34 and 29% difference, respectively). This contrasted with the control subjects whose upright end-diastolic volumes at rest, at 300 kpm/min and at peak exercise were reduced 21, 10 and 3%, respectively, compared with supine values. Cardiac index measurements reflected the reduced left ventricular end-diastolic volume observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

The risk for systemic embolization associated with percutaneous balloon valvuloplasty in adults. A prospective comprehensive evaluation.

STUDY OBJECTIVE: To prospectively investigate the evidence for embolic phenomena associated with percutaneous mitral and aortic valvuloplasty. DESIGN: Prospective, consecutive case series before and after balloon valvuloplasty. SETTING: Referral center hospital and cardiac catheterization laboratory. PATIENTS: Consecutive sample of 32 patients having balloon valvuloplasty for critical symptomatic stenosis of the mitral or aortic valve. Twenty-six patients had aortic stenosis; 6 had mitral stenosis. INTERVENTION: Computed tomography of the head, funduscopy, and electrocardiography were done in all patients before and after valvuloplasty. Cardiac isoenzymes were measured serially in 19 patients. MEASUREMENTS AND MAIN RESULTS: Previous cerebral infarction was seen in nine patients, with three showing a new abnormality after aortic valvuloplasty. In one of these patients a funduscopic hemorrhage was detected by photography. Total creatinine kinase and MB fraction were elevated in 1 of 19 patients. Serial electrocardiograms were unchanged in all patients. CONCLUSIONS: The incidence of cerebral neurologic events and myocardial injury are acceptably low after balloon valvuloplasty of calcific aortic and mitral stenosis. Both episodes of symptomatic cerebral infarction occurred in patients with apparent bicuspid aortic valvular stenosis, suggesting that calcific bicuspid aortic stenosis may be associated with more neurologic events after aortic valvuloplasty.

Adult↗
PubMed1987

Accuracy of digital angiography for quantitation of normal coronary luminal segments in excised, perfused hearts.

The accuracy of coronary artery diameter determination by digital angiography was assessed by imaging 39 coronary segments of excised dog and human hearts and comparing these segments with pathologic sections 0.76 to 3.31 mm in luminal diameter. Digital images were obtained postmortem both during contrast injection using a fixed-pressure coronary perfusion system and after fixation when the coronary size was maintained by injection of a barium-gelatin casting mixture. Digital data were analyzed with commercially available, automated edge-detection software using a coronary catheter as the calibration standard. Coronary diameter measured during contrast injection was not significantly different from that measured after casting and fixation. Digital data from both methods correlated well with diameters from pathologic sections (injected, r = 0.85; fixed, r = 0.91). Linear regression parameters comparing pathologic diameters with the contrast injection method were slope = 0.82, intercept = 0.42 mm, and standard error of the estimate = 0.27 mm. Parameters for the comparison of pathology with casted coronary data were slope = 0.95, intercept = 0.16 mm, and standard error of the estimate = 0.23 mm. Intra- and interobserver variability were 3% (0.05 mm) and 4% (0.07 mm), respectively. These data indicate that when a coronary catheter as a calibration standard is used, coronary artery dimensions can be accurately measured by automated digital angiography techniques.

Angiography↗
PubMed1987

Safety and efficacy of inferior vena caval occlusion to rapidly alter ventricular loading conditions in idiopathic dilated cardiomyopathy.

To investigate the safety and efficacy of inferior vena caval (IVC) balloon occlusion for preload alteration in humans, 13 patients with dilated cardiomyopathy were studied before and during repeated (total of 78) IVC occlusions. Left and right ventricular (LV and RV) micromanometer pressures were simultaneously measured and M-mode and 2-D echocardiograms were recorded at end expiration. Complications were limited to abdominal discomfort in 2 patients. With IVC occlusion, RV collapse fluoroscopically shifted the heart toward midline and ventricular septal motion was frequently disordered. Significant (p = 0.001) changes occurred in RV and LV systolic peak pressures (from 19 +/- 6 to 12 +/- 5 mm Hg and from 129 +/- 34 to 109 +/- 25 mm Hg, respectively). LV and RV end-diastolic pressures also decreased significantly (from 18 +/- 7 to 6 +/- 6 mm Hg and from 5 +/- 3 to 2 +/- 2 mm Hg, respectively) (both p less than or equal to 0.0055). Similarly, LV end-diastolic diameter decreased 13% (from 61 +/- 11 to 53 +/- 12 mm, p = 0.0002). Mean heart rate did not change significantly (from 76 +/- 19 to 78 +/- 21 beats/min). Thus, IVC balloon occlusion provides a safe method of repeatedly altering loading conditions in humans. This approach allows for acquisition of important information regarding cardiac chamber dynamics while minimizing the effects of reflex mechanisms and avoiding use of pharmacologic agents.

Adult↗
PubMed1987

Position as a variable for cardiovascular responses during exercise.

Twenty-one normal young male subjects underwent resting and exercise (bicycle) radionuclide angiography in the full supine and 70 degrees upright tilt positions in order to examine the effects of position on left ventricular size and performance, hemodynamics, and exercise duration. All subjects also underwent full (90 degrees) upright bicycle ergometry with respiratory gas analysis to establish the level of maximal exercise capacity for each. Body position significantly (p less than 0.05) affected resting and exercise cardiovascular parameters. End-diastolic and endsystolic left ventricular volumes and stroke volume were larger in the supine position, both at rest and during exercise. The cardiac output at rest and during exercise were comparable for the two positions; an increase in resting and exercise heart rate in the 70 degrees tilt position compensated for the reduced stroke volume of this posture. At maximal exercise, the 70 degrees upright position was associated with a greater response in left ventricular ejection fraction, otherwise this parameter was not position related. Exercise capacity, in terms of duration and workload, was significantly higher in the supine (1870 +/- 390 s) and full upright (1830 +/- 250 s) positions than in the 70 degrees tilt position (1730 +/- 260 s). Changes in body position significantly alter parameters of ventricular, cardiovascular, and exercise performance.

Adult↗
PubMed1987

Histologic and biochemical correlates of left ventricular chamber dynamics in man.

To investigate the relation between left ventricular chamber dynamics in humans and the quantitative analysis of the histologic and biochemical characteristics of left ventricular endomyocardial biopsy material, 15 patients with a wide range of ventricular function were studied. The pressure-volume relation was determined using simultaneous gated radionuclide angiography, echocardiography and micromanometer pressure. The derived chamber dynamics were then compared with quantitative histologic data (percent fibrosis and cell diameter) and adenosine triphosphate content measurements obtained from the left ventricular biopsy specimen obtained at the time of the pressure-volume studies. The measures of systolic function correlated linearly with high energy phosphate content. The adenosine triphosphate/protein ratio (nanomoles) was shown to parallel ejection fraction (r = 0.81), peak ejection rate (r = -0.73) and peak positive maximal rate of rise in left ventricular pressure (dP/dt) (r = 0.79). No correlation was observed between these variables and the percent fibrosis or cell diameter. Variable results were found in comparing the diastolic properties of the left ventricle with the biopsy data. In general, the high energy phosphate content correlated with measures of active relaxation, but not with the passive filling characteristics of the left ventricle. The adenosine triphosphate/protein ratio was linearly related to peak negative dP/dt (r = -0.74) and the peak filling rate (r = 0.76) but correlated less well with other measures of active and passive diastolic filling. No correlation was found between any diastolic variable and the percent fibrosis or cell diameter.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗