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Biomedical subjects

T M Bateman

Publications and source records attributed to T M Bateman.

At least 37 records · Page 2Linked to original sources

Ineffectiveness of colchicine for the prevention of restenosis after coronary angioplasty.

Colchicine, an antimitogenic agent, has shown promise in preventing restenosis after coronary angioplasty in experimental animal models. A prospective trial was conducted involving 197 patients randomized in a 2:1 fashion to treatment with oral colchicine, 0.6 mg twice daily (130 patients), or placebo (67 patients) for 6 months after elective coronary angioplasty. Treatment in all patients began between 12 h before angioplasty and 24 h after angioplasty. Compliance monitoring revealed that 96% of all prescribed pills were ingested. Demographic characteristics were similar in colchicine- and placebo-treated groups. A mean of 2.7 lesions/patient were dilated. Side effects resulted in a 6.9% dropout rate in the colchicine-treated patients. Complete quantitative angiographic follow-up was obtained in 145 patients (74%) with 393 dilated lesions. Quantitative angiographic measurements were obtained in two orthogonal views at baseline before angioplasty and immediately and at 6 months after angioplasty. The quantitative mean lumen diameter stenosis before angioplasty was 67% both in the 152 lesions in the placebo-treated group and in the 241 lesions in the colchicine-treated group; this value was reduced to 24% immediately after angioplasty in the lesions in both treatment groups. At the 6-month angiogram, lesions had restenosed to 47% lumen diameter narrowing in the placebo-treated group compared with 46% in the colchicine-treated group (p = NS). Forty-one percent of colchicine-treated patients developed restenosis in at least one lesion compared with 45% of the placebo-treated group (p = NS). In conclusion, colchicine was ineffective for preventing restenosis after coronary angioplasty.

Angioplasty, Balloon, Coronary↗

X-ray computed tomography of the cardiovascular system.

X-ray CT of the heart is an evolving field. The ultrafast CT scanner provides a practical method of applying the high spatial resolution, high density resolution, and tomographic capabilities of conventional CT scanning, permitting an evaluation of the cardiovascular system. Multiple reports demonstrate that the basic ultrafast technology, while in an evolving state, permits comprehensive evaluation of cardiac structure and function. Recent studies suggest that with further modification ultrafast CT may ultimately be able to delineate the anatomy of the proximal coronary arteries and bypass grafts and to quantitate perfusion. If all these are possible, x-ray CT will have an expanded role in the evaluation of patients with known or suspected heart disease.

Aorta, Thoracic↗

Sensitivity and specificity of assessing coronary bypass graft patency with ultrafast computed tomography: results of a multicenter study.

Because a significant number of all patients seen by cardiologists have had coronary bypass surgery, a relatively noninvasive method of assessing coronary bypass graft patency would be very helpful. Ultrafast computed tomography, by virtue of its rapid data acquisition time and reasonable spatial resolution, may be useful in this regard. To determine the sensitivity, specificity and predictive accuracy of this imaging modality as compared with cardiac catheterization, a multicenter study was undertaken. There were two parts to the study. Part I involved the evaluation of 179 grafts in 74 patients studied in the five participating centers between March 1985 and August 1986. Twenty-nine percent of these graft studies were found to be technically inadequate and were excluded before patency determinations began. The remaining group of 127 bypass grafts in 62 patients had studies adequate for interpretation. Fifty-one grafts were to the left anterior descending coronary artery or a diagonal branch, 37 to branches of the left circumflex artery and 28 to the right coronary artery or a posterior descending vessel; in addition, there were 11 internal mammary artery bypass grafts primarily into the left anterior descending or diagonal artery distribution. The sensitivity of detecting angiographically open grafts was 93.4%, the specificity of detecting angiographically closed grafts 88.9% and the predictive accuracy was 92.1%. A subsequent study (Part 2) was performed 9 months later to assess the ability to carry out technically adequate examinations. Of the 138 consecutive graft examinations (50 patients) included in this part of the study, 94.2% of the examinations were found to be technically adequate.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

Comparison of esmolol and nitroprusside for acute post-cardiac surgical hypertension.

Because acute systemic hypertension early after cardiac surgery has been linked to catecholamine elevation, an open-label, randomized, crossover study was performed to compare the efficacy of esmolol, a new ultra-short-acting intravenous beta-blocking agent, to nitroprusside, the standard therapy. Controlled drug infusions to maximal dosage (esmolol, 300 micrograms/kg/min, and nitroprusside, 10 micrograms/kg/min) were titrated to achieve at least a 15% reduction in systolic pressure. The blood pressure (BP) endpoint was achieved with esmolol (within 29 +/- 14 minutes) in 18 of 20 patients (90%), compared with 19 of 20 (95%) with nitroprusside infusion (within 21 +/- 15 minutes, difference not significant [NS]). Systolic BP decreased from 170 +/- 13 to 136 +/- 12 mm Hg (mean +/- standard deviation) with esmolol and from 170 +/- 13 to 141 +/- 13 mm Hg with nitroprusside infusion (both p less than 0.05). Diastolic BP was reduced from 71 +/- 12 to 64 +/- 11 mm Hg with esmolol and from 71 +/- 12 to 52 +/- 13 mm Hg with nitroprusside infusion (both p less than 0.05). Esmolol infusion resulted in decreased heart rate, cardiac index and stroke volume index and increased right atrial pressure (all p less than 0.05), whereas nitroprusside infusion resulted in increased heart rate and cardiac index and decreased right atrial pressure, pulmonary arterial wedge pressure and systemic vascular resistance (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic beta-Antagonists↗

Experimental evaluation of technetium-99m red blood cell radionuclide ventriculography for detecting pericardial bleeding.

Abnormal loculated or diffuse blood pools adjacent to the heart have been observed in patients with pericardial bleeding who have been imaged by gated equilibrium radionuclide ventriculography (RNV). To study the scintigraphic appearance of fresh pericardial blood, we performed equilibrium RNV in six dogs with measured volumes (10, 30, or 50 ml) of intrapericardial blood. Loculated and diffuse pericardial blood was simulated by injecting the blood either into an intrapericardial balloon, or freely into the pericardial space. Ability to detect pericardial blood was determined by blinded review, and blood volume analysis was attempted by measuring its scintigraphic thickness, brightness (relative to the left ventricle), extent, and background-subtracted count rate and a peak count index. Detection rates for 10, 30, and 50 ml were all 100% for loculated pericardial blood, and 67%, 100% and 100% for free pericardial blood, with the use of three scintigraphic views. Visually determined "extent" of the abnormal blood pool was the most reliable indicator of pericardial blood volume. When the volume was 30 ml or more, at least 40% of the heart was surrounded in 26 of 27 cases (96%); the specificity of this finding was 90%. We conclude from this animal study that RNV should be a sensitive method for detecting pericardial bleeding; visual appearance permits qualitative assessment of the volume of accumulated labeled blood.

Animals↗

Treatment of severe platelet dysfunction and hemorrhage after cardiopulmonary bypass: reduction in blood product usage with desmopressin.

Impairment of platelet function commonly occurs after cardiopulmonary bypass, and may result in substantial bleeding. Because desmopressin acetate (a synthetic analogue of vasopressin) shortens bleeding time in a variety of platelet disorders, a controlled clinical trial of intravenous desmopressin was performed in 39 patients with excessive mediastinal bleeding (greater than 100 ml/h) and a prolonged template bleeding time (greater than 10 minutes) more than 2 hours after termination of cardiopulmonary bypass. Twenty-three desmopressin recipients and 16 control patients (no desmopressin) were similar in surgical procedure, pump time, platelet count, template bleeding time and amount of bleeding before therapy (p = NS). Compared with the control group, the patients receiving desmopressin (20 micrograms; mean 0.3 micrograms/kg) utilized fewer blood products (29 +/- 19 versus 15 +/- 13 units/patient; p less than 0.05), especially platelets (12 +/- 9 versus 4 +/- 7 units/patient; p = 0.004), while achieving a similarly effective reduction in mediastinal bleeding (4.8- and 4.3-fold, p = 0.001 for both). Severe platelet dysfunction was partially corrected within 1 hour after desmopressin infusion, during which interval no blood products were administered: the template bleeding time shortened (from 17 to 12.5 minutes, p less than 0.05), whereas the platelet count remained unchanged (at 96 +/- 35 and 105 +/- 31 X 10(3)/mm3, p = NS). The plasma levels of two factor VIII components increased: procoagulant activity (VIII:C) from 0.97 +/- 0.43 to 1.52 +/- 0.74 units/ml (p less than 0.05) and von Willebrand factor (VIII:vWF) from 1.28 to 1.78 units/ml (p less than 0.05); these increases correlated with the shortening of the bleeding time (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Platelet Disorders↗

Comprehensive noninvasive evaluation of left atrial myxomas using cardiac cine-computed tomography.

This report describes the first clinical experience with ultrafast (cine) computed tomography for evaluating intracardiac masses. Two patients had a left atrial myxoma that was comprehensively described (size, location, site of attachment and relation to the mitral valve) preoperatively by cine-computed tomography. The information content of the studies exceeded that of two-dimensional echocardiography, and both patients were operated on without invasive cardiac catheterization. This early experience with a new minimally invasive high temporal and spatial resolution technology suggests that cine-computed tomography may be uniquely suited for precise evaluation of intraatrial masses.

Female↗

Mitral valve replacement early after myocardial infarction: attendant high risk of left ventricular rupture.

Between 1969 and 1983, 608 patients underwent mitral valve replacement surgery at Cedars-Sinai Medical Center. Perioperative rupture of the left ventricular myocardium complicated seven operations (1.2%), five of them in the 247 patients with concomitant ischemic heart disease. Six ruptures were fatal. Relative incidences of seven previously hypothesized predisposing factors were determined for patients with and without myocardial rupture. In addition, because of the apparent frequency of association with ischemic heart disease and because all ruptures were posterior or posterolateral, patients were also categorized by prior history of posterior myocardial infarction: 177 patients had none, whereas 49 patients had a remote and 21 patients a recent (less than or equal to 1 month) posterior wall infarct. Four ruptures (accounting for 57% of all ruptures) occurred in the 21 patients (19% incidence) with a recent posterior infarct, compared with only three ruptures in the 587 patients (0.5%) without a recent posterior wall infarct (p = 0.000). None of the factors of age, sex, valve pathology, etiology of valve lesion, concomitant coronary disease, valve substitute or intraoperative myocardial preservation were associated with perioperative rupture. These data establish a low overall incidence of ventricular rupture after mitral valve replacement, high fatality and possible etiologic association with recent posterior wall infarction.

Adolescent↗

Prospective evaluation of ultrafast cardiac computed tomography for determination of coronary bypass graft patency.

Twenty-five consecutive patients with 68 independent (single distal anastomosis) saphenous vein aortocoronary and 12 internal mammary bypass grafts (27 to left anterior descending, 10 to diagonal, 23 to left circumflex, 20 to right coronary artery) entered a reader-blinded, prospective, standardized study to establish the accuracy of ultrafast (cine) cardiac computed tomography (CT) for determining graft patency compared with invasive angiography. All patients underwent imaging after injection of 35 to 45 ml of meglumine diatrizoate (Renografin-76; 7 to 9 ml/sec for 5 sec) into an arm vein. Electrocardiographically triggered images were acquired over eight to 16 tomographic levels at 1 cm intervals from aortic arch to mid left ventricle. Criteria for graft patency were contrast opacification on at least two noncontinguous levels and contrast density-time curves morphologically similar to that of the aorta. Ultrafast CT correctly determined that 46 of 48 bypass grafts were patent and 31 of 32 were occluded (sensitivity, specificity, and accuracy 96%, 97%, and 96%); there were no interpretation errors in 23 (92%) of the 25 patients. Accuracy was independent of vessel bypassed and not different for saphenous veins (96%) compared with internal mammary bypasses (100%). This study establishes a 20 min outpatient intravenous injection technique that is highly accurate for determining patency of coronary artery bypass grafts.

Coronary Angiography↗

Cine computed tomographic evaluation of aortocoronary bypass graft patency.

Evaluation of the patency of coronary bypass grafts has previously required hospitalization for invasive angiography. This report of three cases documents the unique capability of cardiac cine computed tomography to easily and accurately define coronary bypass graft patency. In each case, the findings altered therapeutic decisions. This early experience justifies wider application of this technique and suggests that it may eliminate the need for diagnostically motivated graft angiography. Large scale studies to establish the sensitivity and specificity of cardiac cine computed tomography for determining graft patency are indicated.

Coronary Angiography↗

Hemodynamic differentiation of pathologic and physiologic stenosis in mitral porcine bioprostheses.

Porcine bioprostheses are physiologically stenotic valves. Degenerative calcification leading to pathologic stenosis is an increasingly recognized serious late complication of mitral valve replacement with a porcine bioprosthesis. Hemodynamic differentiation of pathologic from physiologic stenosis is important for identification of porcine bioprosthetic valve dysfunction. In 42 patients with a normal Hancock porcine bioprosthesis (standard model, sizes 27 to 33 mm), mean diastolic flow (65 to 461 ml/s), mean gradient (2.0 to 13.4 mm Hg) and effective orifice area (1.1 to 4.4 cm2) were determined at rest, during epicardial pacing (90, 110 and 130/min) and with isoproterenol infusion. A statistically significant increase in mean gradient occurred with increases in flow and decreases in valve size (p less than 0.05). Effective orifice area increased significantly as flow rate increased and as valve size increased (p less than 0.05). These measurements were compared with those in 16 patients with pathologically confirmed porcine bioprosthetic valve stenosis: 8 patients with reoperation (1.1% per patient-year) 3 to 8.5 years after mitral valve replacement and 8 previously reported abnormal cases. Stenotic failure rate was inversely related to valve size (2.1, 1.4, 0.5 and 0% per patient-year for sizes 27 to 33 mm). Stenotic and normal bioprostheses were not accurately differentiated on the basis of a single value for gradient or effective orifice area. A mathematical model that related flow to the square root of the mean gradient allowed complete separation of stenotic from normal prosthetic valve function, after valve size was accounted for and normal confidence limits were established (r = 0.74 to 0.94, sizes 27 to 33, p less than 0.0001). The effective orifice area-flow relation did not provide accurate differentiation of abnormal from normal function. Thus, normal mitral bioprostheses have significant transvalvular gradients whose magnitude depends on flow. Risk of stenotic failure is increased in the smaller valves, which have a larger gradient at implantation. Differentiation of pathologic from physiologic stenosis cannot be made on the basis of a single value for gradient or effective orifice area. Accurate hemodynamic differentiation is achieved by relating mean gradient to mean diastolic flow rate and valve size.

Bioprosthesis↗

Use of esmolol in hypertension after cardiac surgery.

Systolic hypertension, which is common soon after cardiac surgery, increases cardiac work and may threaten fresh vascular anastomoses. Because postoperative hypertension is often associated with elevated catecholamines and preoperative use of beta-blocking agents, esmolol, an ultrashort-acting beta-blocking agent, was compared with nitroprusside in a crossover study in this setting. Twelve patients, 18 to 28 hours after cardiac surgery (coronary artery bypass graft in 9, aortic valve replacement in 2 and valved aortic conduit with reimplantation of coronary arteries in 1 patient) received controlled infusions of esmolol (mean dosage 142 +/- 100 micrograms/kg/min, range 50 to 300 micrograms/kg/min) and nitroprusside (mean dose 1.6 +/- 1.3 micrograms/kg/min, range 0.5 to 2.75 micrograms/kg/min). In this open-label study, choice of the first drug was randomized, after which patients were then crossed over to the other study drug. Therapeutic response (greater than or equal to 15% systolic blood pressure reduction) was achieved in 11 of 12 esmolol patients and 12 of 12 nitroprusside patients. Both drugs significantly lowered systolic and diastolic blood pressure, as well as left ventricular stroke work index. While the cardiac index was decreased by esmolol and increased by nitroprusside, neither drug significantly changed stroke volume index. Systemic vascular resistance, unchanged by esmolol, was decreased significantly by nitroprusside. Oxygen saturation and Pao2, unchanged with esmolol, were both significantly reduced with nitroprusside. Thus, for hypertension early after cardiac surgery, esmolol is safe, effective and rapid and, compared with nitroprusside, results in less unwanted decrease in diastolic blood pressure and oxygen saturation, but there is more decrease in heart rate and cardiac index.

Adrenergic beta-Antagonists↗

Adrenal function following coronary bypass surgery.

Little is known about adrenocortical function after coronary bypass surgery in which moderate to deep hypothermia and cardiopulmonary bypass are used particularly with intraoperative steroid administration. Therefore, we performed a pilot study in which immediately preoperative and 18-hour postoperative serum cortisol levels were determined in eight patients who received 1.0 to 1.5 gm of methylprednisolone intravenously during surgery; postoperative serum cortisol (3 +/- 1 microgram%) levels were lower than preoperative levels (15 +/- 3 microgram%, p less than 0.05). To determine the possible cause of these striking findings, the effects of moderate to profound hypothermia and cardiopulmonary bypass upon adrenocortical functioning were investigated without the influence of intraoperative steroid administration. Serum cortisol and aldosterone levels and their response to adrenocorticotropic hormone (ACTH) (Cortrosyn) were determined before coronary bypass surgery and at various postoperative intervals in seven patients. Postoperative cortisol and aldosterone levels increased markedly over their preoperative values, reaching a maximum at 6 to 12 hours (cortisol 16 +/- 8 vs 63 +/- 23 micrograms%, p less than 0.05, aldosterone 15 +/- 5 vs 51 +/- 22 ng%, p less than 0.05). Adrenal response to ACTH was normal preoperatively, during rewarming from hypothermia, and 18 hours, and 7 days postoperatively. In summary, normal adrenal responsiveness occurs after coronary bypass surgery, in spite of hypothermic cardiopulmonary bypass and the effects of anesthesia, and a single dose of methylprednisolone during surgery is associated with markedly lower serum cortisol levels and prevents the usual adrenal stress response to bypass surgery for at least 18 hours postoperatively.

Adrenal Cortex Function Tests↗

Fibrinolytic therapy of St. Jude valve thrombosis under guidance of digital cinefluoroscopy.

Fibrinolytic therapy is an alternative to urgent reoperation for patients with St. Jude prosthetic valve thrombosis, but requires an accurate method for repeated assessment of prosthetic function. Since the St. Jude valve is not well visualized by conventional cinefluoroscopy, digital subtraction techniques were developed that improved visualization of the value and allowed assessment of leaflet separation and velocity. A 74 year old woman with prosthetic valve thrombosis 5 years after St. Jude aortic valve placement had an opening angle of 58 degrees (normal range 10 to 13; n = 8) with a maximal opening velocity of 1.37 degrees/ms (normal range 2.46 to 2.93). The closing angle was 125 degrees (normal range 120 to 127) with a maximal closing velocity of 1.38 degrees/ms (normal range 2.24 to 3.60). The patient received 250,000 U of streptokinase intravenously, then 100,000 U/h for 72 hours. Improvement in auscultatory findings occurred at 12 hours; repeat digital cinefluoroscopy showed an opening angle of 20 degrees with a maximal velocity of 2.77 degrees/ms, and a closing angle of 126 degrees with a maximal velocity of 1.91 degrees/ms. Digital cinefluoroscopy 4 weeks after discharge on warfarin and dipyridamole therapy was unchanged. There have been no thromboembolic complications after 6 months of follow-up. Thus, digital cinefluoroscopy is a new noninvasive technique that permits accurate measurement of normal and abnormal St. Jude leaflet function. Intravenous streptokinase dissolution of prosthetic valve thrombosis under digital cinefluoroscopic guidance may be an acceptable alternative to emergency reoperation. The frequency and significance of residual subclinical leaflet dysfunction after fibrinolytic therapy and the indications for elective reoperation require further evaluation.

Aged↗

Esmolol: a new ultrashort-acting beta-adrenergic blocking agent for rapid control of heart rate in postoperative supraventricular tachyarrhythmias.

Prompt control of heart rate is important for successful treatment of supraventricular tachyarrhythmias early after open heart surgery when sympathetic tone is high and ventricular response rates may be rapid. Esmolol, a new ultrashort-acting (9 minute half-life) beta-receptor blocking agent, was given by continuous intravenous infusion for up to 24 hours in 24 patients (21 with isolated coronary bypass surgery and 3 with valve replacement) 1 to 7 days after surgery. Atrial fibrillation was present in 9 patients, atrial flutter in 2 and sinus tachycardia in 13. Eleven patients had received intravenous digoxin (average dose 0.6 mg, average serum level 1.19 mg/100 ml) before esmolol infusion without adequate control of the supraventricular tachyarrhythmia. After a 1 minute loading infusion of esmolol (500 micrograms/kg per min), maintenance dose, titrated to heart rate and blood pressure response, varied from 25 to 300 micrograms/kg per min. After esmolol administration, at an average dose of 139 +/- 83 micrograms/kg per min, mean heart rate decreased from 130 +/- 15 to 99 +/- 15 beats/min. Within 5 to 18 minutes after initiation of therapy, all patients had achieved a 15% reduction in heart rate at a maintenance dose of 150 micrograms/kg per min or less. A 20% reduction in heart rate was attained in 19 of the 24 patients, and conversion to sinus rhythm occurred during esmolol infusion in 5 of the 11 patients with atrial flutter or fibrillation. Transient asymptomatic hypotension (less than 90/50 mm Hg) was seen in 13 patients, requiring cessation of esmolol therapy in 2.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic beta-Antagonists↗

Fascicular conduction disturbances and ischemic heart disease: adverse prognosis despite coronary revascularization.

In patients with ischemic heart disease, fascicular conduction disturbances are associated with increased mortality. This study reveals that increased mortality also exists for certain types of fascicular conduction disturbances after myocardial revascularization. In 227 consecutive patients undergoing bypass surgery, 24 had preoperative and an additional 52 developed at surgery a fascicular conduction disturbance. At 66 +/- 14 months of follow-up, 6 (4%) of 148 control patients without pre- or postoperative fascicular conduction disturbances had died from cardiac causes. Although right bundle branch block and left hemifascicular block were the most common form of fascicular conduction disturbance, only 1 of 55 of these patients died (p = NS). Mortality rates were much higher for patients with left bundle branch block or an intraventricular conduction defect; 8 (38%) of 21 died from cardiac causes (p less than 0.05). A high risk subgroup was identified by comparing 14 consecutive patients with left bundle branch block or an intraventricular conduction defect who survived more than 1 year postoperatively with 21 consecutive patients with these same conduction defects who died within 1 year of surgery. The following variables were significantly (p less than 0.05) different (survivors versus nonsurvivors): age (58 +/- 7 versus 65 +/- 9 years); class IV angina (2 of 14 versus 16 of 21), prior myocardial infarction (9 of 14 versus 21 of 21), left ventricular ejection fraction (53 +/- 18 versus 41 +/- 15%), three vessel disease (9 of 14 versus 20 of 21) and left ventricular aneurysm (2 of 14 versus 13 of 21).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

Cardiac causes of shock early after open heart surgery: etiologic classification by radionuclide ventriculography.

Early after open heart surgery, cardiac shock due to tamponade is easily misdiagnosed as ventricular dysfunction. The distinction is critical to successful therapy. We assessed the utility of 99mTc-red blood cell, gated equilibrium radionuclide ventriculography in 50 patients with early postoperative cardiac shock after historical, clinical, and invasive hemodynamic evaluation failed to identify either tamponade or ventricular dysfunction as the specific cause of their shock. The cause was established by radionuclide ventriculography in 45 of 50 patients and led to a change in therapy in 21 patients. A single cause was found in 35 patients: 13 had severe global dysfunction of the left ventricle (three patients), right ventricle (seven patients), or both ventricles (three patients); three had severe segmental left ventricular dysfunction; and 19 had an exaggerated region of photon deficiency (nine patients) or an abnormal and accumulating blood pool (10 patients) surrounding small hyperdynamic ventricles. Sixteen of these 19 patients with scintigraphic evidence of tamponade underwent aspiration with a pericardial needle or reoperation early after radionuclide ventriculography, resulting in confirmation of scintigraphic findings and improved hemodynamics. Ten additional patients had combined ventricular dysfunction and a pericardial abnormality, and five of these underwent reoperation resulting in improved hemodynamics. Radionuclide ventriculography provided no explanation for the cause of cardiac shock in five patients. Thus, the various causes of cardiac shock early after open heart surgery can be distinguished by 99mTc-red blood cell, gated equilibrium radionuclide ventriculography, eliminating diagnostic uncertainty that can occur with traditional evaluation.

Adult↗