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Biomedical subjects

K B James

Publications and source records attributed to K B James.

At least 19 recordsLinked to original sources

Exercise performance and chronotropic response in heart failure patients with implantable left ventricular assist devices.

During metabolic stress testing, 9 of 20 patients with left ventricular assist devices exhibited a lag in peak device rate by < or = 85% of peak native heart rate (group I), with peak device rates of 118 +/- 9 beats/min compared with group II, in which peak device rate nearly equaled peak native rates. Peak systolic blood pressure was significantly greater in group II than group I, but there was no significant difference in peak oxygen consumption, anaerobic threshold, or peak flows.

Adult

Comparison of mortality rates and progression of left ventricular dysfunction in patients with idiopathic dilated cardiomyopathy and dilated versus nondilated right ventricular cavities.

This study assesses the influence of right ventricular (RV) dilation on the progression of left ventricular (LV) dysfunction and survival in patients with idiopathic dilated cardiomyopathy (IDC). Using transthoracic echocardiography, we studied 100 patients with IDC aged 20 to 80 years (mean 55 +/- 14); 67% were men. In the apical 4-chamber view, diastolic LV and RV chamber area measurements classified patients into 2 groups: group RV enlargement+ (RV area/LV area > 0.5) included 54 patients; group RV enlargement- (no RV enlargement) had RV area/LV area < or = 0.5. Echocardiographic studies were repeated in all patients after a mean of 33 +/- 16 months. At the time of the initial study, the 2 groups did not differ in age, gender, incidence of atrial fibrillation and diabetes, left ventricular mass, and LV ejection fraction, but the RV enlargement+ group had more severe tricuspid regurgitation and less LV enlargement. After 47 +/- 22 months (range 12 to 96), patients in group RV enlargement+ had lower LV ejection fraction (29% vs 34%, p = 0.006) than patients with initial RV enlargement-. At clinical follow-up, mortality was higher (43%) in patients with initial RV enlargement+ than the RV enlargement- patients (15%), p = 0.002. For survivors, the mitral deceleration time averaged 157 +/- 36 ms; for nonsurvivors or patients who required transplant, the mitral deceleration time averaged 97 +/- 12 ms (p < 0.0001). With use of a multivariate Cox model adjusting for LV ejection fraction, LV size, and age, the relative risk ratio of mortality from initial RV enlargement+ was 4.4 (95% confidence limits 1.7 to 11.1) (p = 0.002). Thus, patients with significant RV dilation had nearly triple the mortality over 4 years and more rapidly deteriorating LV function than patients with less initial RV dilation. In IDC, RV enlargement is a strong marker for adverse prognosis that may represent a different morphologic subset.

Adult

Inflammatory cardiomyopathy. The controversy of diagnosis and management.

This article reviews the theories regarding the causes of lymphocytic myocarditis, including viral and immunologic (cellular versus humoral) causes. Also covered is the relationship of dilated cardiomyopathy to myocarditis, the familial predilection for dilated cardiomyopathy in some cases, shortcomings of the various modalities for diagnosing lymphocytic myocarditis, and the occurrence of lymphocytic myocarditis in association with systemic illnesses. Lastly, treatment options for myocarditis are explored.

Autoimmune Diseases

Inability of serum myocyte death markers to predict acute cardiac allograft rejection.

Acute cardiac rejection involves myocyte necrosis. Hence, markers of myocyte death may be useful in diagnosing rejection. Creatine kinase MB, MB isoforms, and troponins I and T were measured in 186 patients undergoing 365 endomyocardial biopsies. No differences were noted with rejection (rejectors vs. nonrejectors: CK=63.8 U/L and 86.6 U/L, P=0.0881; CK MB=2.04 ng/ml and 2.06 ng/ml, P=0.949; troponin T=0.134 ng/ml and 0.0881 ng/ml, P=0.374; troponin I=0.216 ng/ml and 0.707 ng/ml, P=0.357). The time course of troponins T and I levels in rejectors and nonrejectors do not differ with both groups having early elevations. Markers of myocyte death are inadequate predictors of acute rejection in cardiac allografts. The time course of troponins T and I suggests a possible role as prognostic indicators of outcome.

Acute Disease

Hemodynamic effects of a single intravenous injection of synthetic human brain natriuretic peptide in patients with heart failure secondary to ischemic or idiopathic dilated cardiomyopathy.

Synthetic human brain natriuretic peptide (sBNP) is a polypeptide with the same amino acid sequence as the naturally occurring hormone. Preclinical studies have demonstrated that BNP has potent hemodynamic, diuretic, and natriuretic effects that might be beneficial in treating patients with heart failure. This study was a randomized, double-blind, placebo-controlled, ascending-dose trial of sBNP administered as a single intravenous bolus in 27 heart failure patients. Six groups of patients received sequentially increasing doses of sBNP (0.3, 1, 3, 10, 15, and 20 micrograms/kg, respectively) as a single intravenous injection, and hemodynamics were assessed by pulmonary artery monitoring catheter. The 10 and 15 micrograms/kg doses of sBNP resulted in significant reductions in pulmonary capillary wedge pressure (-73%, p < 0.001), mean pulmonary artery pressure (-41%, p < 0.001), mean arterial blood pressure (-28%, p = 0.001), and systemic vascular resistance (-53%, p = 0.004). Significant increases occurred in cardiac index (68%, p < 0.001) and stroke volume index (72%, p < 0.001). The magnitude and duration of hemodynamic changes were dose dependent. There were no adverse effects. sBNP injected as a single intravenous bolus in heart failure patients improves hemodynamics in a dose-related fashion. Further clinical investigations to determine the use of sBNP in decompensated heart failure are clearly warranted.

Cardiomyopathy, Dilated

Plasma volume and its regulatory factors in congestive heart failure after implantation of long-term left ventricular assist devices.

BACKGROUND: Congestive heart failure is associated with blood volume expansion caused by stimulation of the renin-aldosterone system and arginine vasopressin. The use of left ventricular assist devices as bridges to heart transplantation has improved the survival of patients during this critical period. In studying heart failure physiology on support devices, we hypothesized that improvement of cardiac function by a left ventricular assist device is associated with normalization of volume load secondary to normalization of its regulatory substances. METHODS AND RESULTS: We studied 15 patients (13 men, 2 women: age 51 +/- 8 years) with end-stage heart failure who were cardiac transplant candidates eligible for HeartMate implantation. We measured plasma volume and plasma levels of atrial natriuretic peptide, aldosterone, renin, and arginine vasopressin sequentially before HeartMate implantation (baseline), after HeartMate implantation (weeks 4 and 8), and after transplantation. Baseline plasma volume was 123 +/- 20% of normal; it was 122 +/- 22% at week 4 and decreased to 115 +/- 14% at week 8. Atrial natriuretic peptide was 359 +/- 380 pg/mL at baseline, 245 +/- 175 pg/mL at week 4, and 151 +/- 66 pg/mL at week 8. Plasma aldosterone fell from 68 +/- 59 ng/dL at baseline to 17 +/- 16 ng/dL at week 4 (P < .05 versus baseline) and was 32 +/- 50 ng/dL at week 8. Plasma renin activity decreased from 80 +/- 88 ng/dL at baseline to 11 +/- 12 ng/dL at week 4 and was 16 +/- 38 ng/dL at week 8 (both P < .05 versus baseline). Arginine vasopressin fell from 5.0 +/- 4.8 fmol/mL at baseline to 1.1 +/- 0.7 fmol/mL at week 4 and 1.2+/-0.8 fmol/mL at week 8 (both P < .05 versus baseline). CONCLUSIONS: The reduction of plasma renin activity, plasma aldosterone, and arginine vasopressin occurred earlier than the reduction of plasma volume and atrial natriuretic peptide after HeartMate implantation, possibly because of decreased pulmonary congestion and improved renal perfusion. The reduction of atrial natriuretic peptide cannot be responsible for the lack of adequate decrease of plasma volume; its reduction can be taken as a marker of improved cardiac pump function and decreased atrial stretch.

Blood Volume

Left ventricular echocardiographic and histologic changes: impact of chronic unloading by an implantable ventricular assist device.

OBJECTIVES: We studied the effects of chronic left ventricular unloading by a ventricular assist device and assessed left ventricular morphologic and histologic changes. BACKGROUND: The implantable left ventricular assist device has been effective as a "bridge" to cardiac transplantation. Although there are reports documenting its circulatory support, little is known about the effects of chronic left ventricular unloading on the heart itself. METHODS: We performed intraoperative transesophageal echocardiography at the insertion and explanation of a HeartMate left ventricular assist device in 19 patients with end-stage heart failure. They were supported by the assist device for 3 to 153 days (mean [+/-SD] 68 +/- 33). Measurements were taken retrospectively to obtain left atrial and ventricular diameters and interventricular septal and posterior wall thicknesses. Histologic examinations were made from the left ventricular myocardial specimens of 15 patients at the times of insertion and explanation for heart transplantation. Insertion and explanation specimens were compared qualitatively (0 to 3 scale) for wavy fibers, contraction band necrosis and fibrosis, with quantitative measurement of minimal myocyte diameter across the nucleus. RESULTS: Left atrial and left ventricular diastolic and systolic diameters decreased immediately after insertion of the left ventricular assist device (from 46 to 35, 63 to 41 and 59 to 36 mm, respectively, all p < 0.001). Left ventricular wall thickness increased from 10 to 14 mm (p < 0.001) for the interventricular septum and from 10 to 13 mm for the posterior wall (p<0.001). No echocardiographic measurements showed significant subsequent changes at the chronic stage. Myocardial histologic findings demonstrated a reduction in myocyte damage (from 1.9 to 0.5, p<0.001, for wavy fiber and from 1.3 to 0.2, p<0.01, for contraction band necrosis) and an increase in fibrosis (from 1.3 to 1.9, p<0.05), but without significant change in myocyte diameter (from 15.6 to 16.8 micrometer, p=0.065). CONCLUSIONS: Left ventricular unloading with the implantable assist device induces an immediate increase in wall thickness, consistent with the reduction in chamber size, thereby decreasing wall stress. Chronic unloading allows myocardial healing and fibrosis without evidence for ongoing myocyte damage or atrophy. Left ventricular assist device insertion may have a role in "resting" the ventricle for selected patients with heart failure.

Adult

Application of tilt sensors in functional electrical stimulation.

Tilt sensors, or inclinometers have been investigated for the control of Functional Electrical Stimulation (FES) to improve the gait of persons who had a stroke or incomplete spinal cord injury (SCI). Different types of tilt sensors were studied for their characteristics and their performance in measuring the angular displacement of leg segments during gait. Signal patterns of the lower leg with inertial tilt sensors were identified with control subjects and subjects with footdrop who are being stimulated during level walking. To minimize acceleration responses when the foot swings or hits the ground, we use low-pass filtering (1.5-2 Hz). A finite state approach allows the sensor fixed on the shank to effectively detect the step intention in a population of stroke and incomplete SCI subjects and to control the FES. When the lower leg tilts backward, the common peroneal nerve is stimulated to bring the foot up and forward. We have designed a miniature footdrop stimulator with a magnetoresistive tilt sensor built in, so no external sensor cables are required. The thresholds to turn the stimulator on and off can be adjusted, as well as the maximum period of stimulation and the minimum interval between periods of stimulation. This device features several important advantages over traditional AFO's or stimulators controlled by foot switches. Initial trials with stroke and SCI subjects have demonstrated substantial gait improvement for some subjects, while most liked the good cosmesis and ease of using the device with a tilt sensor.

Biomechanical Phenomena

Effect of the implantable left ventricular assist device on neuroendocrine activation in heart failure.

BACKGROUND: The HeartMate left ventricular assist device has been successfully used as a bridge to cardiac transplantation. Because many patients exhibit marked clinical improvement in their heart failure after HeartMate implantation, we studied the physiological effect of this device on the neurohormonal axis. METHODS AND RESULTS: In 13 patients awaiting transplant (mean cardiac index, 1.7 +/- 0.3 L.min-1.m-2) who underwent HeartMate implantation, venous atrial natriuretic peptide, epinephrine, norepinephrine, plasma renin activity, angiotensin, and arginine vasopressin were measured immediately before insertion and at explant/transplantation. Mean time to explant was 86 +/- 40 days. All patients were taken off inotropic medications within 1 month. Mean cardiac index on support before explant was 3.1 +/- 0.9 L.min-1.m-2. Plasma renin activity decreased from 57 +/- 56 ng.mL-1.h-1 at baseline (before insertion) to 3 +/- 3 ng.mL-1.h-1 at explant (mean percent change, 92%; P < .001). Angiotensin II level decreased from 237 +/- 398 U/L at baseline to 14 +/- 14 U/L at explant (mean percent change, 73%; P < .001). Plasma epinephrine level fell from 6800 +/- 1323 pg/mL at baseline to 46 +/- 46 pg/mL at explant (mean percent change, 86%; P < .001). Norepinephrine level decreased from 2953 +/- 1457 pg/mL at baseline to 518 +/- 290 pg/mL at explant (mean percent change, 79%; P < .001). Atrial natriuretic peptide fell from baseline values of 227 +/- 196 to 168 +/- 40 pg/mL at explant (mean percent change, -49%; P = 519); and arginine vasopressin level decreased from 6 +/- 6 pg/mL at baseline to 0.8 +/- 0.5 pg/mL (mean percent change, 69%; P = .002). CONCLUSIONS: We provide data supporting that the neurohormonal axis markedly improves after HeartMate implantation, providing biochemical confirmation of the improvement in hemodynamic status.

Adult

Cardiac complication from use of cocaine and phenylephrine in nasal septoplasty.

Cocaine hydrochloride is widely used as a topical anesthetic for otolaryngologic surgery. Cardiovascular complications, including myocardial injury, are well-documented side effects of illicit cocaine use. We describe a 23-year-old woman without coronary artery disease who had an acute non-Q-wave myocardial infarction and stunned myocardium after receiving topical phenylephrine hydrochloride and cocaine anesthesia for elective nasal septoplasty. These cases are rare; however, we hope to heighten the awareness of the potential lethal complications of using cocaine, phenylephrine, or the combination of both as topical anesthetics in otolaryngologic practice.

Administration, Topical

Structural and left ventricular histologic changes after implantable LVAD insertion.

Long-term support on the implantable left ventricular assist device (LVAD) produces structural changes in the recipient's heart. To assess the possibility of heart "recovery" we reviewed the records of 19 HeartMate LVAD recipients to determine structural and left ventricular histologic changes during LVAD support. Intraoperative transesophageal echocardiographic studies were performed in the operating room before LVAD insertion, immediately after LVAD insertion, and at explantation and heart transplantation (mean duration of support, 76 +/- 34 days). The initiation of LVAD pumping led to an immediate decrease (p < 0.001) in left ventricular dimensions, which were not significantly different by the time of device explantation. Left ventricular fractional shortening did not significantly improve during LVAD support (0.07 +/- 0.03 before LVAD; 0.11 +/- 0.10 immediately after LVAD; 0.11 +/- 0.11 before explantation). Histologic specimens showed a significant reduction in the number of wavy fibers, and contraction band necrosis (p < 0.01), both markers of acute myocyte damage. However, myocardial fibrosis increased (p < 0.05). Myocyte diameter increased slightly (p = 0.07). We conclude that implantable LVAD support is associated with immediate changes in ventricular structure. Histologic markers of acute myocyte damage improve, but fibrosis increases. Because the structural changes occur immediately, they do not indicate "recovery" of left ventricular function, but merely changes in loading conditions.

Adult

Hemodynamic and physiologic changes during support with an implantable left ventricular assist device.

To evaluate hemodynamic effectiveness and physiologic changes on the HeartMate 1000 IP left ventricular assist device (Thermo Cardiosystems, Inc., Woburn, Mass.), we studied 25 patients undergoing bridge to heart transplantation (35 to 63 years old, mean 50 years). All were receiving inotropic agents before left ventricular assist device implantation, 21 (84%) were supported with a balloon pump, and 7 (28%) were supported by extracorporeal membrane oxygenation. Six patients died, primarily of right ventricular dysfunction and multiple organ failure. Nineteen (76%) were rehabilitated, received a donor heart, and were discharged (100% survival after transplantation). Pretransplantation duration of support averaged 76 days (22 to 153 days). No thromboembolic events occurred in more than 1500 patient-days of support with only antiplatelet medications. Significant hemodynamic improvement was measured (before implantation to before explantation) in cardiac index (1.7 +/- 0.3 to 3.1 +/- 0.8 L/min per square meter; p < 0.001), left atrial pressure (23.7 +/- 7 to 9 +/- 7.5 mm Hg; p < 0.001), pulmonary artery pressure, pulmonary vascular resistance, and right ventricular volumes and ejection fraction. Both creatinine and blood urea nitrogen levels were significantly higher before implantation in patients who died while receiving support. Renal and liver function returned to normal before transplantation. We conclude that support with the HeartMate device improved hemodynamic and subsystem function before transplantation. Long-term support with the HeartMate device has a low risk of thromboemboli and makes a clinical trial of a portable HeartMate device a realistic alternative to medical therapy.

Adult

Left ventricular diastolic dysfunction in lymphocytic myocarditis as assessed by Doppler echocardiography.

Pulsed-wave Doppler echocardiography of left ventricular (LV) inflows was performed in 30 consecutive patients with biopsy-proven lymphocytic myocarditis. There were 21 men and 9 women (mean age 50 +/- 15 years). LV ejection fraction was < or = 30% in 73% of the patients. Sixty-six percent were in New York Heart Association functional class III to IV. Peak early (E) velocity, late (A) velocity, deceleration time and filling pattern were assessed. These values were compared with a control population. E velocity in lymphocytic myocarditis was significantly higher than in control subjects (79 +/- 34 vs 67 +/- 14 cm/s, p = 0.0034). A velocity was lower in patients with myocarditis than in control subjects (38 +/- 20 vs 49 +/- 12 cm/s, p = 0.0001). Correspondingly, the E/A ratio was greater in the myocarditis group (2.5 +/- 1.3 vs 1.5 +/- 0.5, p < 0.0001). In particular, mean deceleration time in patients with myocarditis was significantly lower than that of control subjects (151 +/- 52 vs 194 +/- 30 ms, p < 0.0001). Diastolic filling patterns were abnormal in 29 of 30 patients (97%) with lymphocytic myocarditis, revealing a restrictive pattern in 25, abnormal relaxation in 4 and a normal pattern in 1. Lymphocytic myo-carditis is therefore associated with LV diastolic dysfunction of a predominantly restrictive pattern.

Adult

Prognosis of patients with left ventricular dysfunction, with and without viable myocardium after myocardial infarction. Relative efficacy of medical therapy and revascularization.

BACKGROUND: The uptake of F-18 deoxyglucose into dysfunction segments after myocardial infarction identifies metabolically active (FDG+) or inactive (FDG-) myocardium. Although patients with FDG+ segments have been found to be at risk for adverse events, the prognostic significance of viable myocardium in relation to other influences on postinfarction prognosis, including revascularization, remain ill defined. The purpose of this study was to investigate the relative prognostic significance of FDG+ tissue and to establish whether myocardial revascularization in patients with viable tissue attenuates the risk of adverse outcome. METHODS AND RESULTS: One hundred thirty-seven patients with left ventricular dysfunction and resting perfusion defects after myocardial infarction underwent positron emission tomography with both dipyridamole stress Rb-82 perfusion imaging and FDG imaging. After the exclusion of 4 patients proceeding to transplantation, 2 with uninterpretable scans and 2 lost to follow-up, 129 patients were followed clinically for 17 +/- 9 months. Four groups were defined: patients with FDG+ dysfunctional myocardium who were revascularized (n = 49) or treated medically (n = 21) and those with FDG- segments who were revascularized (n = 19) or treated medically (n = 40). The groups of patients with FDG+ or FDG- findings, with and without revascularization, did not differ with respect to known determinants of postinfarction prognosis: age, left ventricular ejection fraction, or the prevalence of multivessel disease. Nonfatal ischemic events occurred in 48% of medically treated FDG+ patients compared with 8% of revascularized patients with FDG+ tissue (P < .001) and 5% of patients with FDG- myocardium (P < .001). Thirteen patients died from cardiac causes; 11 (85%) had a left ventricular ejection fraction of < 30%, and these patients were evenly distributed between FDG+ and FDG- groups. Using Cox's proportional hazards model, only the presence of FDG+ myocardium (odds ratio, 12.9; P < .001) and the absence of revascularization (odds ratio, 5.8; P = .002) independently predicted ischemic events, while only age (P = .02) and ejection fraction (P < .001) but not the presence of viable myocardium were predictive of death. CONCLUSIONS: Residual viable myocardium after myocardial infarction may act as an unstable substrate for further events unless it is revascularized. Despite this association, age and left ventricular dysfunction remained the strongest predictors of cardiac death after myocardial infarction in these patients with a spectrum of left ventricular dysfunction.

Aged

Implantable left ventricular assist device. Approaching an alternative for end-stage heart failure. Implantable LVAD Study Group.

BACKGROUND: The implantable left ventricular assist device (LVAD) was designed to provide circulatory support as an alternative to heart transplantation or to continued medical therapy of end-stage heart failure. Initial experience with the implantable LVAD used as a bridge to heart transplantation provides a clinical opportunity to study the function of the device and adaptation by the patient. METHODS AND RESULTS: Nineteen heart transplant candidates (mean age, 50 years; 17 males) underwent insertion of the HeartMate LVAD as a bridge to heart transplantation from December 1991 to November 1993. All patients were in cardiogenic shock on inotropes, and 16 (84%) were on an intra-aortic balloon pump. Three patients died because of multiple organ failure; all had right ventricular (RV) dysfunction (2 required RV assist devices). Sixteen patients (84%) improved markedly and were rehabilitated to New York Heart Association functional class I-II. Three patients are still on support. Significant improvements in hemodynamic function (based on analysis of the percent change from pre-LVAD condition to pretransplantation) were observed: cardiac index rose from 1.6 +/- 0.2 to 3.2 +/- 0.9 L/min per m2 (P = .0002), left atrial pressure fell from 22.9 +/- 9.5 to 8.0 +/- 5.5 mm Hg (P = .003), RV ejection fraction increased from 19.8 +/- 11.3% to 40.8 +/- 8.9% (P = .0004), pulmonary vascular resistance decreased from 5.2 +/- 2.6 to 2.0 +/- 0.8 Wood units (P = .004). Thirteen patients had successful transplants after a mean duration of 66 days on the LVAD (range, 22 to 101 days). There were no thromboembolic events while the patients were on the LVAD. Only aspirin with dipyridamole was given for anticoagulation during a total of > 1100 patient days of support. CONCLUSIONS: Bridge to transplant implantable LVAD experience indicates that hemodynamic improvement should be significant after insertion of the devices and that the risk of thromboembolic events with the HeartMate LVAD should be extremely low. Rehabilitation and quality of life should be markedly improved. Limitations of extrapolating this clinical experience to the permanent implantable LVAD include that these patients were hospitalized (permanent implants will be outpatients); the "vented-electric" HeartMate LVAD was not tested (it is a portable, battery-powered device), and true "chronic" LVAD support (> 1 year) was not tested, so questions regarding long-term device reliability and the chronic risk of infection are unknown.

Equipment Design

Contribution of peripheral afferents to the activation of the soleus muscle during walking in humans.

Small, rapid stretches were applied to the soleus muscle during the stance phase of walking by lifting the forefoot with a pneumatic device. Stretch responses were induced in the soleus muscle by the disturbance. The amplitude and time course of the responses from the soleus muscle were a function of both the kinematics of the disturbance and the time in the step cycle when the disturbance was applied. The step cycle was divided into 16 equal time parts, and data obtained within each of these parts were averaged together. The electromyographic (EMG) response of the soleus muscle showed a time course that was similar to the time course of the angular velocity induced by the disturbance at the ankle. Three linear equations were used to predict the EMG response from the soleus muscle as a function of the angular kinematics of the disturbance: 1) velocity, 2) velocity and displacement, 3) velocity, displacement and acceleration. Introduction of a pure delay between the EMG and the kinematics substantially improved the predictions. Most of the variance (70%) in the EMG response could be accounted for by the velocity of the disturbance alone with an optimal delay (average 38 ms). Inclusion of a displacement term significantly increased the variance accounted for (85%), but further addition of an acceleration term did not. Since the velocity of the disturbance accounted for most of the variance, the reflex gain was estimated from the velocity coefficient. This coefficient increased in a ramp-like fashion through the early part of the stance phase, qualitatively similar to the increase in the H-reflex.(ABSTRACT TRUNCATED AT 250 WORDS)

Afferent Pathways

Electrocardiographic criteria for anterior myocardial infarction.

In a two-stage review, electrocardiographic patterns associated with anterior infarction were determined in 135 patients whose diagnoses were established by contrast ventriculography. The five most common findings were tested in 1,324 consecutive patients to assess sensitivity, specificity, and predictive accuracies for anterior myocardial infarction. The criteria were shown to have high positive predictive accuracy and specificity levels, and confirmed the value of the standard 12-lead electrocardiogram for detecting anterior myocardial injury.

Electrocardiography