Biomedical subjects

A B Nichols

Publications and source records attributed to A B Nichols.

At least 19 recordsLinked to original sources

PubMed1989

Importance of balloon size in coronary angioplasty.

The effect of balloon size on the success of coronary angioplasty was studied to develop quantitative criteria for optimal selection of balloon size. Coronary dimensions of 165 stenotic lesions were measured by computer-assisted cinevideodensitometry in 120 patients who had undergone angioplasty with a balloon selected by visual estimates. Cross-sectional areas and diameters of normal and stenotic arterial segments were measured before and after angioplasty by a previously validated cinevideodensitometric technique. The diameter of the inflated balloon compared with that of the normal arterial segment was expressed as a ratio for sizing balloons. Oversized balloons with a ratio greater than 1.3 (n = 35) caused a high (37%) incidence of dissection, with three severely compromised arterial lumens. Undersized balloons with a ratio less than 0.9 (n = 29) often resulted in significant (greater than 50% diameter stenosis) residual stenotic lesions (21%) and a significantly (p less than 0.05) higher rate of repeat angioplasty for restenosis. Selection of balloon sizes with ratios in the 0.9 to 1.3 range (n = 101) resulted in a low (4%) incidence of dissection with few patients (3%) having significant residual stenosis. Mean residual stenosis (percent diameter reduction) was most severe for undersized (35.0 +/- 18%) or oversized (23.1 +/- 19%) balloons and least severe for balloons with a ratio of 0.9 to 1.3 (18.7 +/- 14%) (p less than 0.001). Repeat angioplasty for restenosis was more frequently required (p less than 0.05) for lesions dilated with undersized balloons. Thus, selection of angioplasty balloons that approximate or slightly exceed the diameter of the normal arterial diameter yields optimal angiographic results with minimal dissections and minimal residual stenotic lesions.

Angioplasty, Balloon↗

PubMed1989

Relation between survival and development of coronary artery disease and anti-HLA antibodies after cardiac transplantation.

The importance of chronic humoral rejection in cardiac transplant patients has not been studied extensively. In an attempt to determine whether lymphocytotoxic antibodies are related to heart allograft survival, we evaluated 123 patients whose sera were monitored for cytotoxic antibodies against HLA antigens after transplantation. Patients underwent serial sampling of peripheral blood at the time of right-heart catheterization and endomyocardial biopsy. Patients with three or more sera containing lymphocytotoxic antibodies were considered alloantibody producers (81 of 123 patients). With similar follow-up, mortality was greater for antibody producers (27 of 81 patients) than for nonproducers (three of 42 patients, p less than 0.01). Among antibody producers, the mortality rate was higher when multiple samples obtained during the first 6 months after transplantation contained anti-HLA class I or class II antibodies. Coronary artery disease was documented in 12 of 81 antibody producers and only one of 42 nonproducers (p = 0.05). The presence of anti-HLA antibodies in the serum showed no association with the presence of lymphocytic infiltrates in myocardial biopsies or with hemodynamic abnormalities. However, histologic rejection was present in 14 of 19 antibody producers who died. Thus, the presence of anti-HLA antibodies was associated with increased mortality and the development of coronary artery disease and was a major correlate of the clinical course after cardiac transplantation. High- and low-risk groups can be differentiated within the first 6 months after transplantation.

Coronary Disease↗

PubMed1988

Cinevideodensitometric analysis of the effect of coronary angioplasty on coronary stenotic dimensions.

The accuracy and reproducibility of caliper and cinevideodensitometric measurements of coronary stenotic dimensions were compared in radiographic phantom models and in coronary arteriograms of 28 patients undergoing coronary angioplasty. Projected, single-plane coronary cine frames were analyzed by a computer-assisted videodensitometric method, which measures stenotic cross-sectional area without assumptions about lesion geometry. The accuracy (2.4%) and precision (+/- 1.9%) of cinevideodensitometry for measuring percent area stenosis in Plexiglas models of eccentric stenotic lesions was superior to the accuracy (24.7%) and precision (+/- 5.4%) of caliper measurements. Interobserver variability was significantly (p less than 0.05) better for cinevideodensitometric (r = 0.98; SEE = 6.4%) than for caliper measurements (r = 0.87; SEE = 13.1%). After angioplasty, percent diameter stenosis measured by calipers fell from 70 +/- 12% to 30 +/- 15%. Mean percent area reduction measured by cinevideodensitometry fell from 89.1 +/- 8% to 40.1 +/- 22% and stenotic area increased five-fold, from 0.59 +/- 0.5 to 3.47 +/- 1.6 mm2. Pre and post PTCA gradients did not correlate with lesion dimensions. Cinevideodensitometric measurements of absolute stenotic dimensions were more reproducible than relative measurements expressed as a percentage, due to the tapered caliber of normal arterial segments. Thus, cinevideodensitometric measurements were more accurate and reproducible than caliper measurements. The angiographic effects of coronary angioplasty are best measured by cinevideodensitometry, because residual lesions post PTCA are often eccentric, have indistinct margins, and are better characterized by changes in area than by changes in diameter.

Angioplasty, Balloon↗

PubMed1988

Effect of isolated proximal coronary stenotic lesions on distal myocardial perfusion during exercise.

This study tested the hypothesis that the absolute dimension of a coronary stenotic lesion is a more important determinant of its hemodynamic effect on regional myocardial perfusion during exercise than is relative percent stenosis. In 31 patients with an isolated lesion of the left anterior descending coronary artery, regional myocardial perfusion was determined from thallium-201 scans recorded in the left anterior oblique projection after symptom-limited treadmill exercise. Thallium-201 uptake in the distribution of the left anterior descending coronary artery was expressed as a ratio of thallium-201 uptake in the left circumflex artery distribution. Percent area stenosis, minimal cross-sectional area and mean diameter of each stenotic lesion were measured by computer-assisted cinevideodensitometric analysis of projected coronary arteriograms digitized in a 512 X 512 pixel matrix with 256 gray levels. Thallium-201 uptake in the left anterior descending coronary artery distribution, expressed as a ratio, correlated poorly (r = 0.65) with relative percent stenosis, but correlated significantly (r = 0.83; p less than 0.05) with absolute lesion area. For all 16 patients with reduced regional perfusion in the left anterior descending coronary artery distribution during exercise, lesion cross-sectional area was less than 1.8 mm2 (mean 0.9 +/- 0.6); for 13 of the 15 patients with normal distal perfusion, the area of the stenotic lesion was greater than 1.8 mm2 (mean 2.7 +/- 0.7; p less than 0.001). Percent coronary stenosis failed to predict flow-limiting lesions.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Circulation↗

PubMed1987

Effect of pacing-induced myocardial ischemia on platelet activation and fibrin formation in the coronary circulation.

The effect of pacing-induced myocardial ischemia on platelet activation and fibrin formation was investigated in seven patients with severe proximal lesions of the left anterior descending coronary artery to determine if acute ischemia activates the coagulation system. Fibrin formation was assessed from plasma levels of fibrinopeptide A. Platelet activation was assessed by levels of platelet factor 4, beta-thromboglobulin and thromboxane B2. Plasma levels were measured before, during and after acute myocardial ischemia induced by rapid atrial pacing. Blood samples were collected from the ascending aorta and from the great cardiac vein through heparin-bonded catheters. The occurrence of anterior myocardial ischemia was established by electrocardiography and by myocardial lactate extraction. No significant transmyocardial gradients in the levels of fibrinopeptide A, platelet factor 4, beta-thromboglobulin or thromboxane B2 were found at rest, during ischemia or in the recovery period, and levels in the great cardiac vein did not change in response to ischemia. These data indicate that pacing-induced myocardial ischemia does not result in release of fibrinopeptide A, platelet factor 4, beta-thromboglobulin or thromboxane B2 into the coronary circulation, and imply that acute ischemia does not induce platelet activation or fibrin formation in the coronary circulation.

Aged↗

PubMed1987

Evaluation of a cinevideodensitometric method for measuring vessel dimensions from digitized angiograms.

A cinevideodensitometric method for measuring the dimensions of small vessels by computer analysis of digitized cineangiograms was developed and validated in radiographic phantom models. With this method, which is based on full-width-at-half-maximum analysis of videodensitometric profile curves, the diameters of contrast-filled plexiglass cylinders ranging from 1.78 mm to 4.14 mm in diameter were measured to within 2% mean error. The theoretical basis for this method of cinevideodensitometric analysis is provided.

Angiography↗

PubMed1986

Progression of coronary atherosclerotic disease assessed by cinevideodensitometry: relation to clinical risk factors.

Progression of coronary artery stenosis was measured using a quantitative, computer-assisted cinevideodensitometric method in 144 arterial segments in 44 subjects undergoing coronary arteriography on two separate occasions at least 6 months apart. Projected coronary arteriograms were digitized into 512 X 512 pixel mode and percent stenosis was calculated by comparing background-corrected videodensitometric values over stenotic and normal segments. Subjects underwent repeat coronary arteriography because of worsening symptoms of angina or heart failure; subjects with renal failure, coronary artery bypass grafts or cardiac transplant were excluded. Clinical variables determined at the time of the first arteriogram included age, sex, serum cholesterol, systolic blood pressure and presence or absence of cigarette smoking, diabetes mellitus and left ventricular hypertrophy. The mean interval between arteriograms was 29.3 months. Overall progression of coronary stenosis was observed in 40 of the 44 subjects; the mean progression at 24 months was 39% (90% confidence interval, 33 to 45%) and at 36 months was 48% (40 to 56%). The degree of overall progression was related to the length of time between arteriograms (F = 5.81, p less than 0.05) and to serum cholesterol level (F = 4.37, p less than 0.05). These data indicate that using an accurate, quantitative method, it is possible to measure progression of coronary artery atherosclerosis within 2 to 3 years of the initial arteriogram. Serum cholesterol appears to be an important determinant of disease progression.

Angiography↗

PubMed1986

Left ventricular mechanical efficiency in coronary artery disease.

The effect of coronary artery disease and prior myocardial infarction on cardiac energetics was determined by measuring left ventricular myocardial blood flow, oxygen consumption (MVO2), efficiency and ejection phase indexes in 36 patients undergoing coronary arteriography. Eight control patients with normal coronary arteriograms and normal left ventricular function, 15 patients with coronary artery disease without prior myocardial infarction and 13 patients with coronary disease and prior myocardial infarction (greater than 6 months) were studied. Left ventricular efficiency was calculated from left ventricular work, myocardial blood flow (measured by clearance of intracoronary xenon-133), and aortic and coronary sinus oxygen content. Left ventricular volumes, mass and ejection phase indexes were measured by quantitative left ventriculography. Left ventricular myocardial blood flow per 100 g/min was reduced in patients with coronary artery disease (49.0 +/- 8; p less than 0.01) and in patients with myocardial infarction (51.6 +/- 10; p less than 0.05) compared with control subjects (62.4 +/- 16), but total left ventricular flow was not reduced because of increased left ventricular mass. As a result, MVO2 did not differ significantly for the three patient groups (control 13.3, coronary artery disease 14.0 and myocardial infarction 14.3 ml/min). In the patients with myocardial infarction, left ventricular work index was reduced (2.4 versus 4.0 kg X m/m2 per min in the control group; p less than 0.001), causing efficiency to be reduced (15.9 versus 28.8% in the control group; p less than 0.001). Decreased efficiency correlated with ejection fraction (r = 0.54), mean velocity of circumferential fiber shortening (MVcf) (r = 0.45) and mean percent chordal shortening (r = 0.43) (all p less than 0.01). These data indicate that in control patients with normal coronary arteriograms, left ventricular myocardial efficiency averages 29%; in patients with coronary disease without myocardial infarction, left ventricular MVO2 and efficiency are in the normal range; in patients with prior myocardial infarction, left ventricular efficiency is significantly reduced as a result of diminished left ventricular work and normal MVO2; and reduced efficiency after myocardial infarction correlates with reduced ejection phase indexes.

Adult↗

PubMed1986

Effect of coronary stenotic lesions on regional myocardial blood flow at rest.

To determine the effect of atherosclerotic coronary lesions on myocardial blood flow in patients at rest, regional myocardial blood flow was measured distal to stenotic lesions in 29 patients with isolated proximal lesions of the left anterior descending artery. Severity of coronary stenosis was measured by computer-assisted cinevideodensitometric analysis of digitized coronary arteriograms. Regional myocardial blood flow was measured from the clearance rate of intracoronary 133Xe injected into the left main coronary artery and recorded with a multicrystal scintillation camera. In 21 patients with stenotic lesions ranging from 19% to 84% area reduction, distal regional myocardial blood flow was normal. In all eight patients with reduced regional myocardial blood flow distal to left anterior descending lesions, the minimum area of each stenotic lesion was less 0.80 mm2 (mean 0.34 +/- 0.2 mm2), minimum calculated diameter was less than 1 mm (mean 0.59 +/- 0.3 mm), and percent stenosis, based on the reduction in cross-sectional area, was greater than 85% (mean 94 +/- 4%). For all patients, distal flow, expressed as a fraction of normal flow, correlated with the lesion cross-sectional area (r = .84), minimum luminal diameter (r = .84), and percent area stenosis (r = -.70). Thus, resting myocardial blood flow distal to stenotic lesions of the proximal coronary arteries remains normal until the degree of narrowing is severe. The dimensions observed for critical coronary stenotic lesions correlate well with theoretical predictions based on fluid mechanics and with experimental preparations in laboratory animals.

Cineangiography↗

PubMed1984

Quantification of relative coronary arterial stenosis by cinevideodensitometric analysis of coronary arteriograms.

A computerized method for measuring relative coronary arterial stenosis by cinevideodensitometric analysis of 35 mm coronary arteriograms was developed and validated. Video images of projected coronary arteriographic frames were digitized into a 512 X 512 matrix (256 gray levels) by computer analysis that compared integrated contrast density measured over stenotic and normal arterial segments after background subtraction. Pixel density was 70 to 80 pixels/mm2 actual area. In phantom studies performed on plexiglass cylinders, cinevideodensitometric measurements correlated linearly with concentration of contrast medium (r = .99), with cross-sectional areas (r = .99) of contrast-filled cylinders 1 to 4 mm in diameter over a wide range of contrast concentrations (25% to 100%), and with relative stenosis of eccentric lesions in the cylinders (r = .99, SEE = 3.9%). In postmortem studies of patients who died after undergoing coronary arteriography, videodensitometric measurements of relative stenosis correlated highly (r = .97, SEE = 7.0%) with percentage stenosis based on actual area measurements obtained histologically with computer-assisted microscopic planimetry. Cinevideodensitometric analysis of coronary arteriograms was reproducible (r = .92, SEE = 7.7%), and interobserver variability was low (r = .99, SEE = 4.3%). In addition, videodensitometry provided comparable values for eccentric coronary lesions filmed in right anterior oblique and left anterior oblique projections (r = .99, SEE = 1.9%). Cinevideodensitometric analysis is an accurate, rapid method for quantifying the relative stenosis of eccentric coronary lesions without manual tracing of arterial borders.

Absorptiometry, Photon↗

PubMed1984

Effect of heparin bonding on catheter-induced fibrin formation and platelet activation.

Pathologic and experimental evidence indicates that platelet activation and fibrin formation contribute to the pathogenesis of angina pectoris, coronary vasospasm and myocardial infarction. Detection of localized intravascular platelet activation and fibrin formation in vivo by selective blood sampling requires catheters that do not induce coagulation ex vivo. We studied the effect of heparin bonding of catheter surfaces on activation of the coagulation system by cardiovascular catheters. Woven Dacron, polyvinylchloride, and polyurethane catheters were tested and compared with identical catheters with heparin-bonded surfaces in 47 patients undergoing percutaneous cardiac catheterization. Platelet activation was measured by radioimmunoassay of plasma platelet factor 4 (PF4), beta-thromboglobulin (BTG), and thromboxane B2 (TXB2) in blood samples withdrawn through catheters, and fibrin formation was assessed by determination of fibrinopeptide A (FPA) levels. In blood samples collected through conventional catheters, FPA, PF4, BTG, and TXB2 levels were markedly elevated; blood sampling through heparin-bonded catheters had no significant effect on FPA, PF4, BTG, or TXB2 levels. Scanning electron microscopy disclosed extensive platelet aggregates and fibrin strands adherent to the surface of conventional catheters but not to heparin-bonded catheter surfaces. This study demonstrates that (1) collection of blood samples through cardiovascular catheters causes artifactual elevation of FPA, PF4, BTG, and TXB2 levels, and (2) heparin-bonded catheter surfaces effectively prevent catheter-induced platelet alpha-granule release and fibrin formation on catheter surfaces. Heparin-bonded catheters will facilitate investigation of the role of intravascular coagulation in coronary artery disease by eliminating catheter-induced fibrin formation and platelet activation.

Adolescent↗

PubMed1983

Validation of the angiographic accuracy of digital left ventriculography.

Digital subtraction angiography enhances the contrast to background signal, enabling the performance of angiography with reduced doses of contrast medium. The objectives of the present study were (1) to validate the accuracy of digital left ventriculography for measurement of left ventricular volumes and segmental contraction; and (2) to compare the hemodynamic effects resulting from low-and high-dose intraventricular contrast injections. Twenty-eight patients underwent digital left ventriculography, performed by intraventricular injection of 7 ml of contrast medium diluted in saline solution, followed by conventional cineangiography of the left ventricle performed with 45 ml of undiluted contrast medium. Left ventricular volumes calculated from digital ventriculograms correlated well with volumes calculated from conventional ventriculograms: end-diastolic volume (r = 0.97, standard error of estimate [SEE] 23.4 ml; end-systolic volume (r = 0.97, SEE 15.4 ml); stroke volume (r = 0.95, SEE 14.7 ml); and ejection fraction (r = 0.97, SEE 3.8%). Segmental left ventricular contraction, measured as percent chordal shortening of hemiaxes, correlated moderately well (r = 0.81, SEE 11.5%). After injection of undiluted contrast medium, left ventricular systolic pressure decreased (133 +/- 31 to 123.5 +/- 27 mm Hg; p less than 0.01) and left ventricular end-diastolic pressure increased (12.0 +/- 7 to 16.9 +/- 10 mm Hg; p less than 0.001). Left ventricular systolic and end-diastolic pressures did not change significantly after injection of diluted contrast medium, and patients had no discomfort. Thus, digital subtraction angiography permits the performance of left ventriculography with markedly reduced doses of contrast medium, obviating the hemodynamic effects resulting from injection of conventional doses of contrast medium. This new approach to left ventriculography provides high resolution ventriculograms for accurate measurement of left ventricular volumes, stroke volume, and ejection fraction.

Adult↗

PubMed1983

Exercise-induced myocardial ischemia in patients with coronary artery disease: lack of evidence for platelet activation or fibrin formation in peripheral venous blood.

The hypothesis that exercise-induced myocardial ischemia is associated with abnormal platelet activation and fibrin formation or dissolution was tested in patients with coronary artery disease undergoing upright bicycle stress testing. In vivo platelet activation was assessed by radioimmunoassay of platelet factor 4, beta-thrombo-globulin and thromboxane B2. In vivo fibrin formation was assessed by radioimmunoassay of fibrinopeptide A, and fibrinolysis was assessed by radioimmunoassay of thrombin-increasable fibrinopeptide B which reflects plasmin cleavage of fibrin I. Peripheral venous concentrations of these substances were measured in 10 normal subjects and 13 patients with coronary artery disease at rest and during symptom-limited peak exercise. Platelet factor 4, beta-thromboglobulin and thromboxane B2 concentrations were correlated with rest and exercise catecholamine concentrations to determine if exercise-induced elevation of norepinephrine and epinephrine enhances platelet activation. Left ventricular end-diastolic and end-systolic volumes, ejection fraction and segmental wall motion were measured at rest and during peak exercise by first pass radionuclide angiography. All patients with coronary artery disease had documented exercise-induced myocardial ischemia manifested by angina pectoris, ischemic electrocardiographic changes, left ventricular segmental dyssynergy and a reduction in ejection fraction. Rest and peak exercise plasma concentrations were not significantly different for platelet factor 4, beta-thromboglobulin, thromboxane B2, fibrinopeptide A and thrombin-increasable fibrinopeptide B. Peripheral venous concentrations of norepinephrine and epinephrine increased significantly (p less than 0.001) in both groups of patients. The elevated catecholamine levels did not lead to detectable platelet activation. This study demonstrates that enhanced platelet activation, thromboxane release and fibrin formation or dissolution are not detectable in peripheral venous blood of patients with coronary disease during exercise-induced myocardial ischemia.

Adult↗

PubMed1983

Left ventricular volume determined from scintigraphy and digital angiography by a semi-automated geometric method.

The utility of a semi-automatic method of measuring left ventricular (LV) volume geometrically from gated blood-pool studies and digital subtraction angiography (DSA) was investigated using computerized edge detection and spatial calibration algorithms. LAO LV volumes determined from gated blood-pool studies were compared to volumes obtained from contrast left ventriculograms in 21 patients and the applicability of this method to DSA was evaluated in 25 additional patients who also had conventional left ventriculography. There was excellent correlation between the two, both for radionuclide studies and for DSA. Computer-based geometric determinations of LV volume appear to be rapid, accurate, and less dependent on subjective operator decisions than previously reported geometric approaches.

Adult↗

PubMed1983

Relationship between segmental thallium-201 uptake and regional myocardial blood flow in patients with coronary artery disease.

The relationship between the spatial distribution of thallium-201 in myocardial perfusion scintigrams and the distribution of left ventricular regional myocardial blood flow was examined in 25 patients undergoing coronary arteriography. Thallium-201 myocardial scintigrams were obtained after symptom-limited exercise and after a 4 hr delay. Regional myocardial blood flow was measured by the xenon-133 clearance method in patients at rest and during rapid atrial pacing to a double product comparable with that achieved during exercise stress testing. Patterns of regional thallium-201 activity and regional myocardial blood flow, recorded in similar left anterior oblique projections, were compared for left ventricular segments supplied by the left anterior descending (LAD) and left circumflex (CIRC) arteries. In 11 patients without significant lesions of the left coronary artery (group 1), thallium-201 was homogeneously distributed in the LAD and CIRC distributions in scintigrams taken during peak exercise; these scintigrams correspond to homogeneous regional myocardial blood flow in the LAD and CIRC regions during pacing-induced stress. In 14 patients with significant lesions of the left coronary artery (group 2), ratios of regional thallium-201 activity in the LAD and CIRC distributions of exercise scintigrams correlated well (r = .84) with ratios of regional myocardial blood flow measured during rapid pacing. Background subtraction altered the relationship between relative thallium-201 uptake and regional myocardial blood flow, causing overestimation of the magnitude of flow reduction on exercise scintigrams. These data indicate that: (1) in patients with normal left coronary arteries, thallium-201 is homogeneously distributed to the left ventricle, reflecting the homogeneous distribution of regional myocardial blood flow over a wide range of mean left ventricular flow rates and (2) in patients with significant lesions of the left coronary artery, the relative spatial distribution of thallium-201 activity in exercise perfusion scintigrams reflects the distribution of regional myocardial blood flow.

Adult↗

PubMed1982

Spatial calibration of digital scintigraphic images: work in progress.

Accurate scintigraphic determination of organ dimensions is often difficult because of the wide variety of camera-collimator combinations and display formats used for imaging. An algorithm (SPACE-CAL) was developed for digital spatial calibration of up to six large- or small-field gamma cameras using various collimators and magnification factors. The algorithm employs a master calibration file that can be used at multiple terminals. An interactive subroutine permits the operator to measure distances and areas directly from the images. Evaluation of three operators' measurements of a pine-tree phantom acquired at various magnifications showed that distances could be measured with a high degree of accuracy. Calculation of ejection fraction from end-diastolic and end-systolic areas determined by SPACE-CAL showed a high correlation with automatic count determinations (r = 0.96) and angiographic calculations (r = 0.93) of ejection fraction in 12 patients. SPACE-CAL provides an easily implemented, reproducible, and rapid method for accurate analysis of organ dimensions in digital images.

Computers↗

PubMed1982

Left ventricular myocardial blood flow in multivessel coronary artery disease.

The relationship between resting left ventricular (LV) myocardial blood flow (MBF) and hemodynamic determinants of myocardial oxygen consumption was investigated in 15 patients with multivessel coronary artery disease (CAD) and in 10 patients with normal coronary arteriograms. Mean LV MBF per unit mass of tissue was measured with a multicrystal scintillation camera from the regional clearance rates of xenon-133 injected into the left main coronary artery. Peak LV wall stress, mean velocity of circumferential fiber shortening (Vcf), rate of ejection during the first third of systole (1/3 SV), LV ejection fraction (EF), and the ratio of peak LV systolic pressure to LV end-systolic volume were measured by contrast left ventriculography. Mean LV MBF per unit mass was significantly reduced (48 +/- 11 vs 67 +/- 12 ml/100 g.min; p less than 0.01) in patients with multivessel CAD. However, none of the patients with CAD experienced chest pain or had electrocardiographic evidence of myocardial ischemia during the resting MBF measurements. Ejection phase indexes were lower in the patients with CAD: LVEF (56 +/- 10% vs 64 +/- 7%, p less than 0.05); 1/3 SV (35 +/- 3 vs 44 +/- 4%, p less than 0.05); and mean Vcf (1.05 +/- 0.30 vs 1.19 +/- 0.27 circ/sec, NS). LV wall thickness (9.8 +/- 1.9 vs 7.5 +/- 1.4 mm, p less than 0.01) and LV mass index (94 +/- 32 vs 64 +/- 17 g/m2, p less than 0.05) were significantly increased in the patients with CAD, accounting for the reduction in peak LV wall stress (276 +/- 73 vs 373 +/- 91 dyn-cm-2 x 10(-3), p less than 0.05) observed in these patients. Multiple regression analysis indicated that indexes of three of the major determinants of myocardial oxygen consumption explained 65% of the variation in MBF in patients with CAD: peak LV stress, mean Vcf and heart rate. After adjustment for these three indexes, the average LV MBF rates were not significantly different in the two patient groups (54.8 +/- 1.8 vs 57.6 +/- 2.3 ml/100 g.min). In both groups, resting LV MBF/beat correlated most highly with peak LV wall stress (r = 0.79). Thus, the reduction in LV MBF per unit mass observed in patients with multivessel CAD at rest is related to lower levels of hemodynamic variables that determine myocardial oxygen consumption. Peak LV wall stress is the most important hemodynamic variable determining the level of resting MBF in patients with and without CAD.

Adult↗

PubMed1982

Fibrinopeptide A, platelet factor 4, and beta-thromboglobulin levels in coronary heart disease.

In vivo platelet alpha-granule release and fibrin I formation were measured in 82 patients with ischemic heart disease by radioimmunoassay of platelet factor 4, beta-thromboglobulin, and fibrinopeptide A. The presence and extent of coronary artery disease were determined by coronary arteriography, and the extent of left ventricular regional dysfunction was assessed by contrast left ventriculography. In patients with abnormal coronary arteriograms without previous myocardial infarction, mean levels of platelet factor 4, beta-thromboglobulin, and fibrinopeptide A were not elevated. In patients in whom myocardial infarction had occurred more than 6 mo previously, platelet factor 4 (8.3 ng/ml; p less than 0.01) and beta-thromboglobulin (33.2 ng/ml; p less than 0.001) levels were significantly elevated, but fibrinopeptide A levels were normal. Levels of platelet factor 4 and beta-thromboglobulin were unrelated to the extent of coronary artery disease. In the patients with prior infarction, beta-thromboglobulin correlated directly with extent of left ventricular regional dysfunction (r = 0.53; p less than 0.01) and inversely with ejection fraction (r = -056; p less than 0.05). In a small group of patients with left ventricular aneurysm, mean fibrinopeptide A levels were also elevated. We interpret these findings as indicating that platelet release in patients with ischemic heart disease results from platelet reaction with previously infarcted myocardium rather than with the atherosclerotic coronary arteries.

Adult↗