摘要:

ABSTRACTDimension change measures of regional ventricular function, such as absolute or percent wall thickening (▵T or %▵T) or segmental shortening (▵L or ▵L), are highly load dependent. In 16 anesthetized mongrel dogs we assessed use of the end-systolic pressure-thickness and endsystolic pressure-length relationships (ESPTR,ESPLR) as more load-independent measures of regional function. We found that the ESPTR and ESPLR could be measured without detectable baroreceptormediated reflex changes in cardiac contractile state. Systemic administration of dobutamine shifted the ESPTR to the right and the ESPLR to the left of control, mainly due to a change in the slope (Ees) of the relationships. Both ▵T,%▵T and ▵L,▵L failed to detect the positive inotropic effect of dobutamine because of an associated reduction in preload. With systemic administration of propranolol, ESPTR, ESPLR, ▵T,%▵T, and ▵L,▵L detected the negative inotropic effect. Thus systemic propranolol shifted the ESPTR to the left and the ESPLR to the right of control, mainly due to a change in Ees. Regional administration of dobutamine shifted the ESPTR and the ESPLR in the direction of positive contractility in the region receiving the drug, whereas simple dimension change measures of regional function failed to detect the inotropic effect because preload fell and the timing of regional end-systole was altered. With regional propranolol both the ESPTR,ESPLR and simple dimension change measures detected the negative inotropic effect. Thus the ESPTR,ESPLR is a reliable measure of regional ventricular function and may be better than simple dimension change measures of regional function, particularly when loading conditions or the timing of regional systole is altered by an intervention.

ISSN:0009-7322    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

ABSTRACTPositron-emission tomography with13N-ammonia and18F-2-deoxyglucose was used to assess regional perfusion and glucose utilization in 31 chronic electrocardiographic Q wave regions in 20 patients. With previously published criteria, regions of infarction were identified by a concordant reduction in regional perfusion and glucose utilization, and regions of ischemia were identified by preservation of glucose utilization in regions of diminished perfusion. Only 10 of the 31 regions (32%) exhibited myocardial infarction tomographically. In contrast, positron tomography revealed ischemia in six regions (20%) and was normal in 15 regions (48%). Even when Q wave regions were reassigned and consolidated to enhance the specificity of the electrocardiogram, uptake of18F-2-deoxyglucose was noted in the majority (54%) of the regions. Neither electrocardiographic ST-T changes nor severity of associated wall motion abnormality reliably distinguished tomographically identified regions of ischemia from infarction. Thus positron tomography reveals evidence of persistent tissue metabolism in a high proportion of chronic electrocardiographic Q wave regions, and commonly used clinical tests do not reliably distinguish hypoperfused but viable regions from tomographically defined regions of myocardial infarction.

ISSN:0009-7322    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

ABSTRACTThe continuity equation suggests that a ratio of velocities at two different cardiac valves is inversely proportional to the ratio of cross-sectional areas of the valves. To determine whether a ratio of mitral/aortic valve orifice velocities is useful in determining aortic valve area in patients with aortic stenosis, 10 control subjects and 22 patients with predominant aortic stenosis were examined by Doppler echocardiography. The ratio of (mean diastolic mitral velocity)/(mean systolic aortic velocity), (Vm)/(Va), and the ratio of (mitral diastolic velocity-time integral)/(aortic systolic velocity-time integral), (VTm)/(VTa), were determined from Doppler spectral recordings. Aortic valve area determined at catheterization by the Gorlin equation was the standard of reference. High-quality Doppler recordings were obtained in 30 of 32 subjects (94%). Catheterization documented valve areas of 0.5 to 2.6 (mean 1.1) cm2. There was good correlation between Doppler-determined (Vm)/(Va) and Gorlin valve area (r = .90, SEE = 0.23 cm2); a better correlation was noted between (VTm)/(VTa) and Gorlin valve area (r = .93, SEE = 0.18 cm2). The data demonstrate the usefulness of Doppler alone in the determination of aortic valve area in adults with absent or mild aortic or mitral regurgitation and no mitral stenosis. Although the use of mean velocity and velocity-time integral ratios requires accurate measurement of mitral and aortic velocities, it does not require squaring of these velocities or measurement of the cross-sectional area of flow.

ISSN:0009-7322    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

ABSTRACTBoth Bayesian analysis assuming independence and discriminant function analysis have been used to estimate probabilities of corodary disease. To compare their relative accuracy, we submitted 303 subjects referred for coronary angiography to stress electrocardiography, thallium scintigraphy, and cine fluoroscopy. Severe angiographic disease was defined as at least one greater than 50% occlusion of a major vessel. Four calculations were done: (1) Bayesian analysis using literature estimates of pretest probabilities, sensitivities, and specificities was applied to the clinical and test data of a randomly selected subgroup (group I, 151 patients) to calculate posttest probabilities. (2) Bayesian analysis using literature estimates of pretest probabilities (but with sensitivities and specificities derived from the remaining 152 subjects [group II]) was applied to group I data to estimate posttest probabilities. (3) A discriminant function with logistic regression coefflcients derived from the clinical and test variables of group II was used to calculate posttest probabilities of group I. (4) A discriminant function derived with the use of test results from group II and pretest probabilities from the literature was used to calculate posttest probabilities of group I. Receiver operating characteristic curve analysis showed that all four calculations could equivalently rank the disease probabilities for our patients. A goodness-of-fit analysis suggested the following relationship between the accuracies of the four calculations: (1) < (2)=(4) < (3). Our results suggest that data-based discriminant functions are more accurate than literature-based Bayesian analysis assuming independence in predicting severe coronary disease based on clinical and noninvasive test results. The accuracy of the Bayesian method is degraded by the assumption of independence and perhaps more importantly by the use of sensitivities and specificities derived from other patient populations with different testing protocols.

ISSN:0009-7322    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

ABSTRACTPlasma levels of lipids, lipoproteins, and apoproteins in 281 patients undergoing cardiac catheterization were correlated with the incidence and severity of coronary artery disease (CAD) to determine if measurements of apoprotein levels are more predictive of the presence and severity of CAD than the corresponding levels of lipoprotein lipids. In 156 men with CAD among 194 men in the study the only variable other than age that correlated with the severity of CAD, defined by the number of lesions and percent stenosis, was the ratio of apoprotein AI to apoprotein B (r = .1908, p < .03). The ratio of apoprotein AI to apoprotein B was a more accurate predictor of the severity ofCAD than was the ratio of the corresponding high-density to low-density lipoprotein levels (coefficients of partial determination of .07 and .035; p < .001 and p < .07, respectively). Multivariate analysis confirmed the independent effect of the ratio of apoprotein AI to apoprotein B on the severity of CAD even after adjustments were made for lipid levels, age, presence of hypertension or diabetes, and therapy with β-blockers or diuretics. Among men with total occlusion of a coronary artery apoprotein E and apoprotein B levels were significantly higher than in control subjects with a similar extent of CAD (p < .03). The lipid profiles of the 37 women with CAD were very different from those of the men. In women, only total triglycerides and apoprotein B levels correlated with the severity of disease (r = .3670, p < .03 and r = .3635, p < .04, respectively), as confirmed by multivariate analysis. The results of this study indicate that levels of certain apoproteins may be more accurate predictors of the severity ofCAD than are the corresponding levels of lipoprotein lipids, in keeping with the pivotal roles of apoproteins in normal and abnormal lipid metabolism. However, lipids and apoproteins are both weak predictors of lesion severity and cannot be used in the diagnosis of CAD.

ISSN:0009-7322    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

ABSTRACTDetermination of short-term myocardial drug uptake and subsequent redistribution was performed in 27 patients with ischemic heart disease for the antiarrhythmic agents lidocaine and mexiletine, using frequent simultaneous measurements of drug concentration in aortic and coronary sinus blood, combined with measurement of coronary sinus blood flow after intravenous bolus injection of the drug. Maximal myocardial drug content per unit resting coronary sinus blood flow (MDC:F) was significantly greater in patients in whom coronary sinus pacing at 100 beat/min was performed during the initial period of drug uptake. Maximal myocardial drug content occurred after 2.4 ± 0.2 (SEM) for lidocaine and after 5.5 ± 0.6 min for mexiletine (p < .001), and pacing did not affect time to maximum myocardial drug content. In nonpaced, but not paced, patients maximal MDC:F was greater in the lidocaine group than that in the mexiletine group. The subsequent efflux of lidocaine from the myocardium was more rapid that that of mexiletine in both paced and nonpaced groups.

ISSN:0009-7322    

出版商:OVID    

年代:1986

数据来源: OVID

ISSN:0009-7322    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

ABSTRACTThe effects of pharmacologically induced changes in myocardial properties on diastolic mitral valve mechanics were studied in five open-chest dogs. After the induction of complete atrioventricular block, the dogs were subjected to a protocol of programmed pacing. During prolonged diastolic pauses, programmed atrial contractions were induced at progressively increasing coupling intervals. Echocardiographically determined mitral valve reopening time was established for each coupling interval in the control state as well as under the influence of calcium or verapamil. Compared with control, calcium caused an increase in myocardial tension from 23.8 ± 3.0 to 30.0 ± 4.6 g/cm2(mean ± SD, p < .005) as well as an increase in mean septal contraction and relaxation velocities from 142 ± 25.9 and 144 ± 15.2 mm/sec to 188 ± 21.7 and 174 + 19.5 mm/sec, respectively (each p < .001). Conversely, verapamil caused a decrease in mean myocardial tension from 23.8 ± 3.0 to 19.4 ± 5.3 g/cm2(p < .001) and in mean septal contraction and relaxation velocities from 142 ± 25.9 and 144 ± 15.2 mm/sec to 112 ± 32.7 and 112 ± 21.6 mm/sec, respectively (each p < .001). At every coupling interval, calcium significantly (p < .01 to .001) prolonged, whereas verapamil significantly shortened (p < .01 to .001), mitral reopening time compared with the control state. These pharmacologically induced changes in mitral valve mechanics occurred despite variations in left ventricular volume, as well as left ventricular and left atrial pressures that under normal conditions exert opposite effects on mitral valve mechanics. Thus, in addition to affecting active systolic and early diastolic myocardial properties, calcium and verapamil also caused marked changes in passive late diastolic myocardial properties as demonstrated by late diastolic alterations in mitral valve mechanics. This experimental preparation offers a unique method for the investigation of late diastolic myocardial properties.

ISSN:0009-7322    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

ABSTRACTWe tested a new rotational thrombectomy catheter in acute thrombi formed both in vitro and in vivo. The catheter consisted of a rounded platinum tip, 0.025 inch diameter by 0.08 inch long, attached to a flexible steel guidewire supported by an external sheath. In vitro, the force required penetrate thrombus was reduced fivefold by rotation of the catheter at 4000 rpm (0.75 + 1.2 g rotating vs 3.9 ± 2.1 g static; p < .001). Fibrin was extracted selectively from the thrombus and tightly wound about the shaft (3.8 ± 1.5 mg rotating vs 0.75 ± 0.4 mg static; p < .001). In vivo, subtotal complete thrombosis of the canine femoral artery was created. Thrombectomy by catheter rotation always produced tightly wound adherent fibrin on the catheter shaft. Angiographic patency was restored in 20 of 22 (91%) arteries, totally in seven of 22 (32%) and partially (>20% increase in lumen diameter) in 13 of 22 (59%). There was one arterial perforation (5%). We conclude that this new mechanical catheter device reduces the force required to penetrate thrombus. Additionally, by winding fibrin about its shaft, the catheter is able to selectively remove the fibrin matrix of thrombus. Thus both the ease of initial thrombus recanalization as well as physical removal of thrombus are promoted by new approach. Such an approach may be relevant to the treatment of recent thrombosis in acute myocardial infarction.

ISSN:0009-7322    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

ABSTRACTIn this study we used transmural multipolar electrodes, sonomicrometers implanted within the left ventricular wall, and cardiac electrical stimulation techniques to examine the effect of transient mechanical posterior papillary muscle traction on local myocardial electrophysiologic characteristics. Nine open-chest dogs were atrially paced (cycle length 400 msec) followed by insertion of timed premature extrastimuli at left ventricular epicardial pacing sites either in the vicinity of (traction zone) or remote from (nontraction zone) the site of papillary muscle traction. Electrophysiologic recordings were made before and during periods of intermittent papillary muscle traction of predetermined timing, application rate (25 cm/sec), and duration (170 msec). Papillary muscle traction was applied in late diastole just before the last beat of each atrial drive train. In seven of nine dogs application of transient papillary muscle traction resulted in significantly earlier local ventricular activation (mean activation advancement 30 ± 13 msec), altered QRS morphology of the last conducted atrial drive-train beat, and relative prolongation of ventricular functional refractory period in the traction zone. Conversely, in nontraction zones in these seven dogs, early activation did not occur and refractoriness remained unchanged as tested by a locally placed extrastimulus. In two of nine dogs traction failed to induce early activation and changes in refractoriness did not occur. Alterations in regional myocardial blood flow (assessed by radioactive microsphere technique) did not appear responsible for the observed changes, since there was no demonstrable traction-induced difference in regional blood flow between the traction and nontraction zones. Thus, in normal myocardium in situ, regional abnormal wall motion may be associated with alterations of local ventricular activation and refractoriness, factors that in the diseased heart may lead to increased susceptibility to arrhythmias.

ISSN:0009-7322    

出版商:OVID    

年代:1986

数据来源: OVID