Systemic reactive angioendotheliomatosis mimicking hypertrophic cardiomyopathy in a domestic shorthair cat.

A two-year-old, 3.9-kg, male castrated, domestic shorthair cat presented to The Ohio State University Veterinary Medical Center for acute onset neurological signs. During hospitalization, he was diagnosed with an American College of Veterinary Internal Medicine (ACVIM) stage B1 hypertrophic cardiomyopathy phenotype on echocardiogram. His clinical signs acutely worsened, including seizure activity and panting, and he was euthanized. Necropsy revealed the histopathologic diagnosis of systemic reactive angioendotheliomatosis, which notably severely affected the myocardium. In this case report, we present the antemortem diagnostic results and postmortem necropsy results of this rare condition in cats. This case demonstrates that echocardiographic assessment of the heart in cats affected by systemic reactive angioendotheliomatosis may lead to the false diagnosis of hypertrophic cardiomyopathy and thus should be considered as a differential diagnosis in cats with symmetrical left ventricularl wall thickening on echocardiography.

Giant pericardial-occupying compressive primary cardiac hemangiosarcoma in a cat.

Hemangioarcoma in the cat is an infrequently diagnosed tumor, and cardiac involvement is rare. We report a previously healthy, 8-year-old, domestic shorthair cat with acute collapse associated with pericardial effusion and cardiac tamponade. Following pericardiocentesis and removal of 15 mL of fluid, the cat improved rapidly. A massive, space-occupying, intrapericardial tumor adhered to and compressing the right atrium and ventricle was detected by echocardiography. Approximately 5 weeks following initial presentation, bicavitary effusion and tachypnea developed, and the cat was euthanized. Necropsy revealed a giant intrapericardial mass adhered to and impinging upon the right heart. Histologic and immunohistochemical examination confirmed hemangiosarcoma with no gross or histologic evidence of metastasis. To the authors' knowledge, this is the first account of a pericardial-occupying, primary feline cardiac hemangiosarcoma resulting in compression of the right heart and cardiac tamponade, Further, this report describes novel clinicopathological relationships between radiographic and echocardiographic findings and gross and microscopic pathology.

The malignant course of acute rheumatic Fever in the modern era: implications for early surgical intervention in cases of bivalvular insufficiency with impaired ventricular function.

In recent years, the incidence of acute rheumatic fever (ARF) has drastically decreased in the United States while remaining common in developing nations. However, immigration to the United States from developing nations has resulted in the continued prevalence of ARF. Patients with ARF face the potential development of significant valvular insufficiency and rheumatic carditis, which are associated with significant morbidity and mortality. Potentially adverse outcomes may be avoided with advanced interventions such as aortic and/or mitral valve replacement or repair, the use of inotropic agents, and ventricular assist devices for mechanical circulatory support. This report describes a series of three ARF carditis cases. This series serves not only to emphasize proper ARF prevention, but also to demonstrate the need for timely surgical intervention once medical therapy has failed.

Prognostication in 3-vessel coronary artery disease based on left ventricular ejection fraction during exercise : influence of coronary artery bypass grafting.

BACKGROUND: Previous data indicate that left ventricular ejection fraction (LVEF) provides prognostic information among patients with coronary artery disease (CAD), but the value of such testing specifically for defining benefits of coronary artery bypass grafting (CABG) may relate to severity of exercise-inducible ischemia measured noninvasively before surgery. METHODS AND RESULTS: To determine the independent prognostic importance of preoperative ischemia severity for predicting outcomes of CABG among patients with extensive CAD, we monitored 167 stable patients with angiographically documented 3-vessel CAD (average follow-up of 9 years in event-free patients) who previously had undergone rest and exercise radionuclide cineangiography. Their course was correlated with data obtained during initial radionuclide testing, coronary arteriography, and clinical evaluation at study entry. Fifty-two patients received medical treatment only, and 115 underwent CABG (44 early [

Prediction of indications for valve replacement among asymptomatic or minimally symptomatic patients with chronic aortic regurgitation and normal left ventricular performance.

BACKGROUND: Optimal criteria for valve replacement are unclear in asymptomatic/minimally symptomatic patients with aortic regurgitation (AR) and normal left ventricular (LV) performance at rest. Moreover, previous studies have not assessed the prognostic capacity of load-adjusted LV performance ("contractility") variables, which may be fundamentally related to clinical state. Therefore, 18 years ago, we set out to test prospectively the hypothesis that objective noninvasive measures of LV size and performance and, specifically, of load-adjusted variables, assessed at rest and during exercise (ex), could predict the development of currently accepted indications for operation for AR. METHODS AND RESULTS: Clinical variables and measures of LV size, performance, and end-systolic wall stress (ESS) were assessed annually in 104 patients by radionuclide cineangiography at rest and maximal ex and by echocardiography at rest; ESS was derived during ex. During an average 7.3-year follow-up among patients who had not been operated on, 39 of 104 patients either died suddenly (n = 4) or developed operable symptoms only (n = 22) or subnormal LV performance with or without symptoms (n = 13) (progression rate=6.2%/y). By multivariate Cox model analysis, change (delta) in LV ejection fraction (EF) from rest to ex, normalized for deltaESS from rest to ex (deltaLVEF-deltaESS index), was the strongest predictor of progression to any end point or to sudden cardiac death alone. Unadjusted deltaLVEF was almost as efficient. Symptom status modified prediction on the basis of the deltaLVEF-deltaESS index. The population tercile at highest risk by deltaLVEF-deltaESS progressed to end points at a rate of 13.3%/y, and the lowest-risk tercile progressed at 1.8%/y. CONCLUSIONS: Currently accepted symptom and LV performance indications for valve replacement, as well as sudden cardiac death, can be predicted in asymptomatic/minimally symptomatic patients with AR by load-adjusted deltaLVEF-deltaESS index, which includes data obtained during exercise.

Differential response to vesnarinone by cardiac fibroblasts isolated from normal and aortic regurgitant hearts.

Vesnarinone, a quinoline derivative with modest positive inotropic action, has been shown in several studies to benefit patients with clinical congestive heart failure. The cellular basis of its clinical benefit is not known, although the drug has several pharmacologic effects demonstrated both in isolated cardiac myocytes and in other noncardiac cell types. To investigate the possibility that the clinical benefit of vesnarinone is based, at least in part, on the inhibition of pathologic myocardial fibrosis, we examined its effects on cultured cardiac fibroblasts isolated from both normal and aortic regurgitant New Zealand White rabbit hearts. As in people, rabbits with moderate-to-severe aortic regurgitation often develop congestive heart failure that, at necropsy, is characterized by exuberant myocardial fibrosis. A dose-response curve was constructed with vesnarinone concentrations ranging from 10(-4 ) to 10(-9 ) mol/L. Cellular survival was decreased by exposure to nanomolar concentrations of drug but not at the higher doses tested. Fibroblasts isolated from normal hearts responded maximally at 10(-7 ) mol/L vesnarinone, whereas fibroblasts from aortic regurgitant hearts responded maximally at 10(-8 ) mol/L. These concentrations of drug are more than an order of magnitude lower than those believed to be associated with clinical benefit from earlier studies. Our results indicate that vesnarinone can suppress cardiac fibroblast proliferation and suggest that this action may be useful in therapies designed to prevent congestive heart failure in aortic regurgitation.

Usefulness of subnormal midwall fractional shortening in predicting left ventricular exercise dysfunction in asymptomatic patients with systemic hypertension.

We have recently shown that a subgroup of asymptomatic hypertensive patients exhibit subnormal left ventricular (LV) midwall fiber shortening at rest and that this finding predicts morbidity and mortality independently of age, blood pressure (BP), or the presence of LV hypertrophy. However, it is unknown whether abnormal midwall fractional shortening predicts either subnormal LV functional reserve or extracardiac damage in asymptomatic hypertensive patients. Accordingly, we compared radionuclide cineangiographic LV ejection fraction at rest and maximum exercise as well as clinical findings between 89 patients with normal and 16 patients with subnormal midwall fractional shortening by echocardiogram. Patients with low midwall fractional shortening were similar in gender, age, and systolic BP to those with normal shortening but had higher mean diastolic BP and body mass indexes (both p < 0.05). The 2 groups also had similar resting ejection fraction (56 +/- 9% vs 55 +/- 15%, with normal or subnormal shortening, respectively, p = NS). Patients with subnormal midwall fractional shortening had higher LV mass and tended to have higher urinary protein excretion and serum creatinine levels. Subnormal LV ejection fraction with exercise (< 54%) was observed in 13 of 89 patients (15%) with normal midwall fractional shortening but in 7 of 16 patients (44%) with subnormal shortening (p < 0.05). Multiple linear regression analysis revealed that midwall fractional shortening independently predicted exercise performance (p < 0.001). Thus, subnormal midwall fractional shortening predicts depressed LV fractional reserve in asymptomatic hypertensive patients and may contribute to identification of patients with extracardiac target-organ damage.

Antimyosin antibody imaging in experimental aortic regurgitation.

BACKGROUND: Fiber dropout and myocyte necrosis precede heart failure in experimental aortic regurgitation (AR). The current study aimed to determine whether this process can be detected by noninvasive scintigraphic imaging. METHODS AND RESULTS: 111In-labeled antimyosin antibody Fab fragment (1 to 1.5 mCi) (Myoscint) was administered to each of 34 New Zealand White rabbits: 11 early (3 to 5 weeks) after surgical AR induction; 9 late (98 to 128 weeks) after AR induction; 5 normal and 3 sham-operated age-matched with early AR; and 3 normal and 3 sham-operated age-matched with late AR. Echocardiographic fractional shortening was indistinguishable among control, early AR, and late AR groups. In vivo gamma camera imaging 24 and 48 hours after isotope administration, post-mortem heart activity determination (percentage injected dose per gram), and autoradiography were performed. At 24 and 48 hours, heart-to-lung counts-per-pixel ratios from in vivo images were greater (p < 0.05) in the late AR rabbits than in each of the three other groups. No significant differences were found when early AR and older or younger control rabbits were compared. Heart activity (percentage injected dose per gram) in late AR rabbits trended toward higher values than in age-matched control rabbits (p = 0.057), but in early AR it was indistinguishable from that in the corresponding control (p = 0.413, difference not significant). The autoradiographic endocardial/epicardial activity ratio in late AR rabbits was greater than in control and early AR rabbits (1.27 +/- 0.13 vs 1.06 +/- 0.09 and vs 1.13 +/- 0.10, respectively, p < 0.02). CONCLUSIONS: Whereas isotope uptake in late AR rabbits differed from that in control and early AR rabbits, systolic function was indistinguishable. Thus 111In-labeled antimyosin antibody imaging may permit noninvasive detection of AR-induced myocardial damage before functional deterioration.

Biodistribution and autoradiographic localization of I-125--labeled synthetic Peptide in aortic atherosclerosis in cholesterol-fed rabbits.

I-125 labeled SP4 is a synthetic oligopeptide derived from apolipoprotein B of low-density lipoprotein that has been shown to localized in atherosclerotic plaques in experimental animals. However, its biodistribution and mechanism of localization need to be further elucidated. Twenty-four cholesterol-fed (CF) and 20 normal (NL) New Zealand White rabbits were injected with I-125-SP4 and killed 15 to 30 min (6 NL; 6 CF) or 2 h (14 NL; 18 CF) later. We obtained aortic autoradiograms and activity concentrations (% injected dose/gm) in aortic segments and other tissues. The uptake of I-125-SP4 was higher in CF than in NL rabbits in all aortic segments (p < 0.05). I-125-SP4 was cleared rapidly in both CF and NL rabbits with 60 to 70% of the injected dose cleared from the blood by 1 h. No statistically significant differences in radiotracer biodistribution were observed between NL and CF rabbits although activity tended to be higher in the liver, gallbladder, and intestine in NL rabbits and in the kidney and spleen in CF rabbits. Silver grains were distributed mainly on foam cells of the fatty streaks in aortic microautoradiograms from two additional rabbits that had been injected with I-125-SP4. There were 23,518 plus minus 15,878 (SD) grains/mm(2) in fatty plaques but only 14,669 plus minus 11,035 grains/mm(2) in media muscle (p < 0.0001 [9 sections, 17 areas evaluated] in an atherosclerotic animal) in injected animals and 13,439 plus minus 5,565 grains/mm(2) in media muscle (two sections, four areas) in the normal control animals (NS versus media of atherosclerotic animal). I-125-SP4 specifically localizes in aortic atherosclerotic plaques in CF rabbits. There is no significant difference in tissue distribution between normal and CF rabbits except in the aorta. Preliminarily, it appears that the site of tracer uptake is on foam cells and this suggests the possibility of relative specificity for fatty plaque.

External imaging of atherosclerosis in rabbits using an 123I-labeled synthetic peptide fragment.

The oligopeptide fragment of apolipoprotein B, SP-4, has demonstrated pronounced uptake in the healing edges of balloon-injured rabbit aortic endothelium. To assess 123I-labeled SP-4 for identification of atherosclerotic plaques by gamma camera imaging, 14 Watanabe heritable hyperlipidemic (WHHL) and 5 normal rabbits were imaged 5 minutes and 12 and 24 hours after intravenous injection of 123I-SP-4. In addition, two WHHL and two normal rabbits were injected with 125I-SP-4 for autoradiography. Twelve of the 14 WHHL, but none of the normal, rabbits had visually apparent focal radioiodine accumulation in the region of the aorta. Focus-to-lung and focus-to-heart count ratios were 2.4 +/- 1.3 and 1.0 +/- 0.4, respectively. Five of the visually positive WHHL rabbits were reimaged 4 and 8 weeks later with 123I-NaI and 123I-SP-2 (an apo E peptide), respectively, as negative controls. Perceptible, but faint, aortic localization of 123I-NaI and of 123I-SP-2 was seen in only one animal each. The distributions of atherosclerotic lesions on photographs of the opened WHHL aortas and of film blackening on 125I-SP-4 autoradiograms were identical. In contrast, the two normal rabbit aortas did not exhibit plaques on photographs or film blackening on autoradiograms. Thus, in an animal model closely simulating human atherosclerotic disease, SP-4 localizes specifically in aortic atherosclerotic lesions.

Prognostic value and physiological correlates of heart rate variability in chronic severe mitral regurgitation.

BACKGROUND: A variety of measures of heart rate variability have been devised to measure high-frequency (0.15-0.40 Hz), low-frequency (0.04-0.15 Hz), or ultralow-frequency (< 0.0033 Hz) fluctuations in sinus cycle length. Although measures of low-frequency and ultralow-frequency heart rate variability have been shown to correlate with prognosis in several populations with ischemic heart disease, their relevance to patients with primary valvular heart disease remains to be determined. METHODS AND RESULTS: Thirty-eight patients with nonischemic causes of chronic severe mitral regurgitation who were in sinus rhythm underwent 24-hour ambulatory electrocardiography as part of a prospective study of the natural history of regurgitant valvular heart disease. Patients were followed for as long as 9.2 years, and end points of mortality, progression to mitral valve surgery, and development of chronic atrial fibrillation were tabulated. Time- and frequency-domain measurements of high-frequency, low-frequency, and ultralow-frequency heart rate variability were computed and compared with resting ventricular function by radionuclide cineangiography and outcome. The standard deviation of the 5-minute mean RR intervals (SDANN), a measure of ultralow-frequency heart rate variability, was correlated with left ventricular ejection fraction (r = 0.49, p = 0.002) and right ventricular ejection fraction (r = 0.43, p = 0.007), whereas low-frequency and high-frequency heart rate variabilities were not. Heart rate, ultralow-frequency heart rate variability, and, to a lesser extent, high-frequency heart rate variability exhibited significant diurnal variation, but low-frequency heart rate variability did not. Heart rate and ultralow-frequency, low-frequency, and combined low- and high-frequency heart rate variability predicted mortality and total events. The most powerful predictor of subsequent events was SDANN: Patients with reduced SDANN were significantly more likely to develop end-point events (p < 0.001) with increased progression to mitral valve surgery (p < 0.001) as well as increased early mortality (p = 0.02). In a multivariate proportional hazards model, SDANN retained independent predictive power (p = 0.001). Likewise, SDANN was the only variable that was significantly associated with the subsequent development of atrial fibrillation (relative risk, 3.1; p = 0.03). CONCLUSIONS: Ultralow-frequency heart rate variability, as measured by SDANN, correlates with right and left ventricular performance and predicts development of atrial fibrillation, mortality, and progression to valve surgery in patients with chronic severe mitral regurgitation.

Noninvasive laser-based blood pressure measurement in rabbits.

To obtain serial blood pressure measurements without trauma in rabbits, we developed a laser-based method which permits noninvasive determination of systolic and diastolic arterial blood pressure. The ease and accuracy of this method were evaluated over a range of blood pressures in five New Zealand White rabbits. Laser-based pressures from the central ear artery were compared with cannula-based pressures from the contralateral central ear artery. Pressures were measured before and during infusions of saline (control), nitroprusside, or epinephrine, and following induction of anesthesia. Noninvasive measurements correlated highly with direct measurements (systole: r = 0.89; diastole: r = 0.93). The difference between the non-invasive and direct pressure measurements during saline, nitroprusside, and epinephrine infusions, and following anesthesia, respectively, were (mean +/- SD, systole/diastole): 4.2 +/- 2.4 (P = NS)/9.3 +/- 1.4 (P less than .001), 4.1 +/- 1.6 (P less than .02)/3.2 +/- 1.1 (P less than .01), 0.6 +/- 2.4 (P = NS)/-3.0 +/- 2.7 (P = NS), and -5.1 +/- 2.9 (P = NS)/0.3 +/- 1.3 (P = NS). The noninvasive method did not result in observable agitation of the animals. To optimize results, visual inspection was required to assure that the instrument's diaphragm was not deformed or dried from previous use, and that the diaphragm was placed over the center of the arterial lumen. It was also necessary to dim room lights and to direct heating lights away from the ears to avoid degrading light signal quality. These results, albeit involving a small number of animals, indicate the potential utility of this method in the study of chronic pathophysiological processes requiring long-term repeated determination of systolic and diastolic blood pressure.

Natural history of left ventricular performance at rest and during exercise after aortic valve replacement for aortic regurgitation.

Previous studies of left ventricular performance in aortic regurgitation uniformly indicate improvement within the year after aortic valve replacement but differ regarding the likelihood of additional later improvement. To resolve this difference, to more precisely define the pattern of postoperative left ventricular performance variation, and to assess the impact of valve replacement on ejection fraction during exercise, we evaluated radionuclide cineangiograms obtained annually or nearly annually for approximately 5 years in 21 prospectively studied patients who had undergone valve replacement for aortic regurgitation. Ejection fraction rose from less than 8 months before operation to 5-11 (average 7) months after operation and continued to rise for 1 additional year (rest) and 2 additional years (exercise) before reaching a stable plateau until the final study 54-72 (average 63) months postoperatively. Mean ejection fractions at rest were 45% preoperatively, 50% less than 1 year postoperatively (p = 0.12), 54% at year 1-2 (p = 0.01 versus less than 1 year), 56% at year 2-3 (NS versus year 1-2) and year 4-6 (NS versus year 1-2 or 2-3), and during exercise were 39% preoperatively, 49% less than 1 year postoperatively (p less than 0.01), 54% at year 1-2 (p less than 0.01 versus less than 1 year, NS versus year 2-3, p less than 0.05 versus year 4-6), 60% at year 2-3, and 61% at year 4-6 (NS versus year 2-3). Late improvement was found most consistently among patients with relatively depressed performance before operation.(ABSTRACT TRUNCATED AT 250 WORDS)

Relative insensitivity of densitometric stenosis measurement to lumen edge determination.

Coronary artery stenosis measurement from coronary arteriograms is dependent on lumen edge determination. In theory, dependence may be minimized by densitometric integration of the entire lumen as compared with densitometric determination of edges alone coupled with calculation of lumen size by geometric formulas. To assess the impact of approximations of lumen border position when densitometric and geometric methods are employed, external, intermediate and internal borders were defined and used with each method to calculate lumen narrowing from images of contrast-filled, asymmetrically stenotic model vessels and from clinically generated coronary arteriograms. Actual cross-sectional area narrowing of models correlated almost perfectly with densitometric narrowing for each of the three border criteria (external: r = 0.99, n = 192; intermediate: r = 0.99, n = 192; internal: r = 0.99, n = 192). Lumen narrowing calculated by assuming a circular lumen geometry with a diameter equal to the distance between these identical borders correlated less well with true area narrowing (external: r = 0.79, n = 192; intermediate: r = 0.83, n = 192; internal: r = 0.78, n = 192); the residual variance of the densitometric regression was significantly less than that of the geometric regression for each of the three border criteria (external: 8.13 versus 372, p less than 0.001; intermediate: 7.39 versus 315, p less than 0.001; internal: 7.13 versus 531, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Relation of concentric left ventricular hypertrophy and extracardiac target organ damage to supranormal left ventricular performance in established essential hypertension.

Increased cardiac performance has been documented in patients with early systemic hypertension, but its prevalence and determinants in patients with uncomplicated sustained essential hypertension have not been characterized. Radionuclide cineangiography in 116 patients with uncomplicated essential hypertension showed that 12 of 116 (10%) had supranormal resting left ventricular (LV) ejection fraction (greater than 70%, above the highest value in normal subjects), while 104 patients had a normal resting ejection fraction (45 to 70%). Patients with a high resting ejection fraction had higher systolic and diastolic blood pressure compared with patients with normal resting ejection fraction (182 mm Hg vs 169, p less than 0.01, and 110 vs 103, p less than 0.05, respectively), markedly greater echocardiographic LV mass (136 vs 94 g/m2, p less than 0.01), smaller ventricular dimensions in systole (2.5 vs 3.1, p less than 0.01) and diastole (4.4 vs 4.9, p less than 0.05), and higher relative wall thickness (0.61 +/- 0.20 vs 0.39 +/- 0.98, p less than 0.001). Patients with supranormal resting ventricular performance had lower end-systolic wall stress than normal volunteers or patients with normal resting LV function (48 vs 64 vs 74 X 10(3) dynes/cm2, respectively). Patients with an elevated LV ejection fraction also had significantly more abnormal funduscopic examinations and greater proteinuria. Thus, a subset of essential hypertensive patients with moderately to severely elevated blood pressure developed marked concentric LV hypertrophy associated with subnormal end-systolic stress and supranormal LV performance.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac structure and function in renovascular hypertension produced by unilateral and bilateral renal artery stenosis.

To evaluate cardiovascular status in human renovascular hypertension, quantitative echocardiographic findings were compared in 42 patients with arteriographically documented renovascular hypertension and 46 age- and sex-matched patients with essential hypertension. Left ventricular (LV) fractional shortening, a measure of systolic performance at rest, was subnormal (less than 26%) in 8 of 42 renovascular hypertensive patients (19%), 0 of 42 essential hypertensive patients (p less than 0.005) and 1 of 79 normal subjects (1%) (p less than 0.005). Fractional shortening was equally reduced in patients with arteriosclerotic and nonarteriosclerotic causes of renal artery stenosis (32 +/- 9% vs 32 +/- 6%, both p less than 0.025 compared with 36 +/- 5% in patients with essential hypertension). The depressed function in renovascular hypertension appeared to be a result of greater LV dilation (p less than 0.02) and septal but not LV free wall hypertrophy (p less than 0.01) that failed to offset the pressure load, allowing end-systolic stress, a measure of myocardial afterload, to increase to abnormal levels (101 +/- 47 X 10(3) dynes/cm2, p less than 0.001 vs 68 +/- 19 in essential hypertension). These data indicate that human renovascular hypertension is associated with more adverse cardiac involvement than essential hypertension of similar severity. In addition, the 14 patients with bilateral renovascular stenosis had a higher cardiac index (3.9 +/- 1.1 liters/min/m2) than the 28 with unilateral stenosis (3.2 +/- 1.1 liters/min/m2, p less than 0.05). This result supports the proposition that bilateral renovascular disease is analogous to 1-clip 1-kidney experimental renovascular hypertension, while unilateral renovascular disease resembles the 1-clip 2-kidney model.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac digital angiography: applications in ventriculography and coronary arteriography.

Clearly, computer-based digital subtraction offers several advantages over conventional approaches to contrast angiography. Using the newer method, in many situations contrast loads can be beneficially reduced, radiation exposure can be markedly diminished, and right ventricle evaluations can be simplified. In addition, storage of data on magnetic tape is less space consuming, and less costly, than storage on film. Over the 5- to 10-year life expectancy of a digitally equipped laboratory, these advantages probably justify the 30-50% increase in the initial monetary outlay for equipment in excess of that required for a conventionally equipped laboratory. However, the greatest promise of digital angiography is in the area of coronary arteriography. If three-dimensional reconstruction of coronary lesions and determination of regional flow can be effected, important advances in diagnosis and in prognostication theoretically might be expected, leading to more appropriate selection of therapy for individual patients than now can be achieved. However, currently available information does not yet indicate the extent to which such potential advantages will be realized. Thus, it will be several years before we will know whether the exciting potential of digital angiography in this area can be reached.