Comparison of radionuclide and contrast ventriculography for detection and quantitation of regions of myocardial ischemia in dogs.

Radionuclide and contrast ventriculography were evaluated for their ability to estimate myocardial ischemia. In 14 closed-chest, sedated dogs, a small and larger region of ischemia were produced by inflating balloon occluders on the left anterior descending coronary artery. The systemic arterial pressure, atrial-paced heart rate, global ejection fraction by radionuclide and contrast ventriculography, regional wall-motion abnormalities (as the percentage of abnormally contracting segments), and regional myocardial blood flow (using the microsphere technique) were measured during an initial control period, two separate ischemic periods, and a final control period. The regional ischemic weights based on myocardial blood flow ranged from 0 to 38.5 g and were grouped as zero, small (range 0 to less than 10 g, mean 3.40 g), and large regions of ischemia (greater than 10 g, mean 24.8 g). Regional wall-motion abnormalities were sensitive qualitative indicators of ischemia. Receiver operating characteristic analysis showed that both ventriculographic methods were highly sensitive, specific, and accurate for detecting regional ischemia. Contrast ventriculography was slightly superior for detecting small regions less than 4 g, but the methods were equal for regions greater than 4 g. The arterial pressure and heart rate were unchanged during ischemia. For small regions of ischemia, the global ejection fraction did not fall using either the contrast or radionuclide technique, but it fell significantly when large regions were produced. There was a quantitative relationship between the percentage of abnormally contracting segments and the grams of myocardial ischemia (for radionuclide ventriculography, r = 0.65, P = 0.003, and for contrast ventriculography, r = 0.75, P less than 0.001), but for many small regions of ischemia, wall-motion changes were greater than anticipated, suggesting hypofunction of the continguous normal tissue. This study demonstrated that both radionuclide and contrast ventriculography were quite sensitive and specific for detecting measured amounts of regional ischemia. The functional changes resulting from ischemia are quantitatively related to the extent of regional ischemia, small areas resulting in regional wall motion abnormalities, and large areas producing both reduced global ejection fraction and wall motion changes.

Beneficial long-term effect of intracoronary perfluorochemical on infarct size and ventricular function in a canine reperfusion model.

The administration of a drug soon after reperfusion that could enhance myocardial salvage would have important clinical application. The aim of this study was to assess the long-term effect of the perfluorochemical, Fluosol DA 20%, on infarct size, infarct morphology, ventricular ectopic activity and serial regional ventricular function in a 2 week closed chest canine model. After 90 minutes of proximal left anterior descending artery occlusion, animals randomly received either oxygenated Fluosol DA (n = 9) or saline solution (n = 9) intracoronary at 15 ml/kg body weight over 20 to 30 minutes. Hemodynamic variables were similar in the two groups except for transient elevation of left ventricular filling pressure immediately after infusion in the treated group. Infarct size was markedly reduced in the perfluorochemical-treated animals when expressed as a percent of the risk region (10.8 +/- 1.8% versus 28.9 +/- 5.5%, p less than 0.02) or as a percent of the total left ventricle (3.7 +/- 1% versus 10.8 +/- 8%, p less than 0.006). This was associated with greater improvement in radial shortening in the jeopardized zone at 2 weeks after reperfusion (15.3 +/- 2.8% versus 5.2 +/- 2.1%, p less than 0.01). Histologic examination revealed adequate healing in the treated animals with an increased number of swollen mononuclear cells in the border zones. Holter electrocardiographic recordings demonstrated a low frequency of ventricular ectopic beats in both groups. This study suggests that the perfluorochemical, Fluosol DA, may be a potentially useful agent in enhancing myocardial salvage after successful reperfusion.

Accuracy of radionuclide ventriculography for estimation of left ventricular volume changes and end-systolic pressure-volume relations.

Estimation of left ventricular end-systolic pressure-volume relations depends on the accurate measurement of small changes in ventricular volume. To study the accuracy of radionuclide ventriculography, paired radionuclide and contrast ventriculograms were obtained in seven dogs during a control period and when blood pressure was increased in increments of 30 mm Hg by phenylephrine infusion. The heart rate was held constant by atropine infusion. The correlation between radionuclide and contrast ventriculography was excellent. In the individual animals, the average r value for left ventricular volume was 0.96 +/- 0.03 (+/- SD) (p = 0.001, n = 7) and the mean r value for end-systolic volume changes was 0.90 +/- 0.08 (n = 7, range 0.76 to 0.99). For the entire series, there were 33 end-systolic volume changes, and there was an equally strong radionuclide-contrast correlation (r = 0.89, p less than 0.001, n = 33), even though the volume changes averaged only 11.9 +/- 8.2 ml (range 0.3 to 38.1). The systolic pressure-volume relations were linear for both radionuclide and contrast ventriculography (r = 0.98 and 0.97, respectively, n = 7). The mean slope for radionuclide ventriculography (2.9 +/- 1.4) was lower than the mean slope for contrast ventriculography (4.8 +/- 1.7) (p = 0.004); however, the slopes correlated well (r = 0.81, n = 7, p = 0.026). The radionuclide-contrast volume relation was compared using background subtraction, attenuation correction, neither of these or both. By each method, radionuclide ventriculography was valid for measuring small changes in left ventricular volume and for defining end-systolic pressure-volume relations.

A new model to study quantitative effects of laser angioplasty on human atherosclerotic plaque.

A new model for analyzing the major effects of the use of any laser angioplasty system is described. Changes in any of the six major determinants of effect (energy, duration, wavelength, medium, absorption, geometry) can be evaluated. In this report a neodymium: yttrium aluminum garnet (Nd:YAG) laser was used to make 408 laser exposures in vitro on segments of human cadaveric atherosclerotic aorta. Energy, medium (air, human blood, perfluorochemical and saline), geometry and duration were varied. The depth and width of the resultant plaque craters were measured. A large amount of exposure to exposure variability was found in all groups of experiments, even when conditions were held as constant as possible in this rigidly controlled laboratory setting. This variability is attributable to differences in energy absorption by the plaque. Changes in media and fiber optic tip to plaque distance also markedly altered exposure outcome. For example, the average depth of the hole created by a 15 W, 2 second blast with the fiber tip adjacent to the plaque in blood was 1.7 +/- 0.1 mm (n = 27), but the range was between 0.5 and 2.7 mm. Under the same conditions, except with the fiber tip 1 mm away from the plaque, the average hole depth was 0.4 +/- 0.1 mm (n = 12) and the range was 0.0 to 1.7 mm. The use of this model to analyze the major determinants of lasing effects in different laser angioplasty systems should help to select the best conditions for lasing and allow assessment of the variability of outcome.

Effects of methoxamine and phenylephrine on left ventricular contractility in rabbits.

The end-systolic pressure-volume relation is employed to evaluate left ventricular contractility. In clinical studies, pharmacologic vasoconstriction is used to increase left ventricular systolic pressure to assess pressure-volume relations. However, the effect of vasoconstrictors on the ventricular contractile state is not well characterized. The effects of methoxamine and phenylephrine on systemic arterial pressure and left ventricular contractility in rabbits were studied with three protocols. In protocol 1, anesthetized rabbits (n = 10) were injected with incremental doses of methoxamine and phenylephrine intravenously. Methoxamine (4 mg) increased the mean arterial pressure by 50 +/- 12% (mean +/- SE) (n = 5, p = 0.001). Phenylephrine (0.2 mg) increased mean arterial pressure by 82 +/- 14% (n = 5, p = 0.004). In protocol 2, isolated blood-perfused hearts were injected with incremental doses of these drugs in the ascending aorta in amounts approximately equal to the concentrations injected in the intact rabbits. Methoxamine (2 mg) reduced isovolumic peak systolic left ventricular pressure by 43 +/- 9% (n = 7, p = 0.003), whereas phenylephrine (0.1 mg) increased the isovolumic pressure by 24 +/- 9% (n = 7, p less than 0.05). These responses indicated an enhanced contractile state with phenylephrine and a reduced contractile state with methoxamine. Pretreatment with propranolol blunted the effect of phenylephrine on isovolumic pressure (n = 6, p less than 0.02). In protocol 3, cross-circulation experiments allowed study of the effect of these drugs on isovolumic left ventricular pressure in the isolated heart and simultaneously on the systemic arterial pressure in the intact anesthetized rabbit (support rabbit).(ABSTRACT TRUNCATED AT 250 WORDS)

Determinants of left ventricular aneurysm formation after anterior myocardial infarction: a clinical and angiographic study.

To determine factors involved in left ventricular aneurysm formation after transmural anterior myocardial infarction, 79 patients with a first myocardial infarction who underwent cardiac catheterization within 6 months of infarction were evaluated. Patients who had received thrombolytic therapy were excluded. Patients were divided into four groups depending on the status of the left anterior descending artery and the presence or absence of a left ventricular aneurysm: Group I (n = 25): aneurysm with occluded left anterior descending artery; Group II (n = 27): no aneurysm and occluded left anterior descending artery; Group III (n = 23): no aneurysm and patent left anterior descending artery; and Group IV (n = 4): aneurysm with patent left anterior descending artery. Single vessel disease was more common in Group I (aneurysm) compared with Groups II and III (no aneurysm) (chi 2(4) = 12.8; probability value equal to 0.012). Collateral blood supply in the presence of an occluded left anterior descending artery was significantly less in Group I (aneurysm) compared with Group II (no aneurysm) (0.9 versus 2.4, p less than 0.001). The extent of coronary artery disease and collateral blood supply in Groups I and II were directly related (p = 0.012). Neither age, sex nor risk factors for coronary disease correlated with aneurysm formation. At a mean follow-up of 48 months, no differences were observed in the incidence of recurrent angina, new myocardial infarction, embolic events or sudden death. More patients in Group II underwent coronary artery bypass surgery. Total occlusion of the left anterior descending artery in association with inherent poor collateral blood supply is a significant determinant of aneurysm formation after anterior myocardial infarction. Multivessel disease with either good collateral circulation or a patent left anterior descending artery is uncommonly associated with the development of left ventricular aneurysm.

Right ventricular myocardial infarction in patients with chronic lung disease: possible role of right ventricular hypertrophy.

To determine the relation between right ventricular hypertrophy and right ventricular myocardial infarction in patients with chronic lung disease, the records of 28 patients with chronic lung disease, inferior myocardial infarction and significant coronary artery disease (group I) and 20 patients with right ventricular hypertrophy, chronic lung disease without inferior myocardial infarction or significant coronary artery disease (group II) were reviewed. Chronic lung disease was diagnosed by clinical criteria, chest radiographs and pulmonary function tests. All patients had postmortem examinations. Patients in group I were classified into two subgroups: group Ia (without right ventricular hypertrophy) and group Ib (with right ventricular hypertrophy). Right ventricular wall thickness was 3.3 mm +/- 0.5 in group Ia, 6.0 mm +/- 1.1 in group Ib and 8.8 mm +/- 2.4 in group II (group Ia versus Ib, p less than 0.001; group Ia versus II, p less than 0.001; group Ib versus II, p less than 0.001). Eleven patients (78.6%) in group Ib (chronic lung disease with both right ventricular hypertrophy and inferior myocardial infarction) had right ventricular myocardial infarction compared with only 3 patients (21.9%) in group Ia (chronic lung disease without right ventricular hypertrophy and with inferior myocardial infarction) (p less than 0.008). Isolated right ventricular myocardial infarction occurred in four patients (20%) in group II (chronic lung disease with right ventricular hypertrophy, but without evidence of infarction of the left ventricle or significant coronary artery disease). There was no significant difference in the extent of anatomic coronary disease in groups Ia and Ib.(ABSTRACT TRUNCATED AT 250 WORDS)

Right ventricular hypertrophy is an important determinant of right ventricular infarction complicating acute inferior left ventricular infarction.

To explore the role of right ventricular hypertrophy and chronic obstructive pulmonary disease in the pathogenesis of right ventricular infarction, 27 consecutive patients with a first inferior left ventricular infarction were prospectively studied. Right ventricular infarction was diagnosed using established hemodynamic criteria. Right ventricular hypertrophy was defined as right ventricular free wall thickness greater than or equal to 5 mm. Patients were classified into two groups: Group I patients with right ventricular infarction (n = 15), and Group II patients without right ventricular infarction (n = 12). The ratio of forced expiratory volume over forced vital capacity (FEV1/FVC) and forced expiratory flow between 25 and 75% expired volume (FEF) as a percent of predicted values were significantly reduced in Group I versus Group II (90 +/- 5 versus 105 +/- 6% and 63 +/- 13 versus 103 +/- 15%, respectively; p less than 0.05). This was associated with increased right ventricular wall thickness (Group I 5.5 +/- 0.3 mm versus Group II 3.9 +/- 0.2 mm, p less than 0.001). Multiple logistic regression analysis demonstrated that right ventricular wall thickness was the strongest predictor of right ventricular infarction (p less than 0.0005). No significant difference was found in the site of right coronary occlusion, collateral blood supply or extent of coronary artery disease between the two groups. These findings suggest that right ventricular hypertrophy predisposes patients with acute inferior myocardial infarction to right ventricular infarction independent of the site or extent of coronary artery disease.

Demonstration of myocardial reperfusion injury in humans: results of a pilot study utilizing acute coronary angioplasty with perfluorochemical in anterior myocardial infarction.

Reperfusion may limit the amount of potentially salvageable myocardium through the introduction of cellular elements into previously ischemic but viable myocardium (reperfusion injury). It has been demonstrated that intracoronary infusion of a 20% intravascular perfluorochemical emulsion (Fluosol) significantly reduces infarct size and results in improved left ventricular function in the canine model. This pilot study was performed to explore the existence of myocardial reperfusion injury in humans. Utilizing Fluosol as a probe in conjunction with emergency coronary angioplasty, 26 patients presenting within 4 h with a first anterior myocardial infarction were randomized to emergency angioplasty or angioplasty followed by a 30-min intracoronary infusion of Fluosol at 40 ml/min. Global and regional ventricular function were assessed immediately and a mean of 12 days after successful angioplasty with contrast ventriculography. Infarct size was semiquantitated with thallium-201 single-photon emission computed tomography (SPECT) images before discharge. Twelve patients (six undergoing angioplasty alone, six treated with angioplasty and Fluosol) had an occluded infarct-related vessel (Thrombolysis in Myocardial Infarction [TIMI] grade 0 to 1) at the time of emergency catheterization and were included in the final analysis. At 12 days after successful angioplasty, the improvement in regional ventricular function was greater in patients receiving adjunctive therapy with intracoronary Fluosol versus those undergoing angioplasty alone utilizing both the radial shortening and centerline method, respectively (23 +/- 3.1% vs. 8 +/- 2.3%, p less than 0.02; and -1.6 +/- 0.4 vs. -2.9 +/- 0.2 SD/chord, p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Ethics in cardiovascular medicine. Task Force IV: Scientific responsibility and integrity in medical research.

Ethical standards are a set of affirmative responsibilities to which the investigator must subscribe; behavior that is incompatible with these responsibilities should be presumed unethical, whether or not it is explicitly proscribed. This Task Force sought to present these standards as principles or guidelines. In undertaking research an investigator must accept that publicly funded or supported research is intended to yield public benefit; personal gain should be only incidental to and not at the expense of the public benefit. The responsibilities of the investigator are summarized as follows: Design of Research To develop a research design that effectively and efficiently addresses the scientific question while minimizing the likelihood of incorrect or misleading results. To protect the rights and welfare of human subjects, assure the humane use of laboratory animals and protect the safety of laboratory workers and the environment. Conduct of Research To ensure that accepted laboratory and research practices are followed and that all data are accurately collected and properly recorded; the investigator must participate in the review of original data. To carry out research in accordance with that approved by the institutional review board and ensure that fully informed consent is obtained, that the welfare of human subjects is protected and that animal welfare and laboratory safety procedures are carried out. To provide effective ongoing supervision of research trainees and technicians. In multidisciplinary collaborative research, to have at least an overview familiarity with the work outside his or her areas of expertise. In fixed protocol, multicenter collaborative research the investigator must be satisfied with the adequacy of the collaborative activities.(ABSTRACT TRUNCATED AT 250 WORDS)

Tricuspid regurgitation following inferior myocardial infarction.

Tricuspid regurgitation developed in two patients after inferior wall myocardial infarction. Neither patient had preexisting valvular heart disease or evidence of endocarditis, and neither had suffered chest trauma. Because abnormalities in right ventricular function may occur after inferior infarction, and because other known causes of tricuspid incompetence were not present, we postulate that these patients developed valvular regurgitation from dysfunction of the papillary muscle complex controlling tricuspid valve function, a mechanism similar to that proposed to explain mitral regurgitation seen with inferior wall ischemia.

Variability of response to beta receptor blockade for angina pectoris in clinical trials: a study of pindolol.

In a randomized, controlled study we found a significant decrease in pressure-rate (double) product and an improvement in exercise tolerance in patients with angina pectoris treated with pindolol. However, when patients were observed in a long-term double-blind crossover study, pindolol treatment did not produce a significant improvement in angina pectoris or exercise tolerance over placebo. Patients treated with placebo had a gradual improvement in exercise tolerance, possibly because of the training effect of multiple treadmill tests and increased daily walking. The individual patient response to pindolol varied, with some patients showing clinical improvement and decreased double product with exercise and some having no clinical improvement despite a similar decrease in double product. Angina occurred at a lower double product with exercise, suggesting that beta receptor blockade adversely affected other variables of myocardial oxygen demand or decreased coronary blood supply. This study illustrates the difficulties with patient variability and study design that are encountered in studies of beta blocker agents for angina pectoris.

Variant angina pectoris: investigation of indexes of sympathetic nervous system function.

One thousand forty-five spontaneous episodes of S-T segment elevation were observed in three patients over a total of 72 days of continuous electrocardiographic monitoring. Eighty-nine percent of episodes were asymptomatic; chest pain tended to occur with episodes longer than 3 minutes, and ventricular ectopy occurred almost exclusively with symptomatic episodes. Nitroglycerin regularly relieved angina or S-T elevation, or both. Plasma and urinary catecholamines and their metabolites were normal. Episodes of variant angina were not associated with a generalized increase in sympathetic outflow because serum catecholamine levels at the onset and termination of the S-T abnormalities were not elevated. Controlled trials of propranolol showed no significant beneficial effect. Propranolol significantly increased the length of episodes of S-T elevation in one patient, increasing ventricular irritability. The overall course of variant angina was quite variable, with spontaneous and long-lasting remissions, necessitating cautions interpretation of clinical trials.

Intrinsic left ventricular contractility in normal subjects.

The influence of autonomic tone on left ventricular (LV) contractility, along with the range of normal values and the effects of exercise on contractile state, were studied in 12 normal volunteers. Serial reproducibility was examined in a subgroup of 6. LV contractility was estimated by the LV peak-systolic pressure to end-systolic volume relation (pressure-volume relation), and the ratio of peak-systolic pressure to end-systolic volume (pressure/volume ratio). The cuff blood pressure and radionuclide ventriculogram were recorded at rest, during exercise and during pharmacologic pressure-afterloading with phenylephrine, before and after vagal and beta-adrenergic "blockade." Both the pressure/volume ratio and ejection fraction increased during the stimulus of exercise (both p less than or equal to 0.008). After blockade, the pressure-volume relations were highly linear (r = 0.95 +/- 0.05 [standard deviation], n = 12), and there was no systematic difference in their slopes induced by blockade. The serial studies of pressure-volume relations showed no significant differences. The results demonstrated that vagal and sympathetic tone were not important in the support of LV contractility in normal subjects at rest, and that the pressure-volume relation and pressure/volume ratio are reproducible between studies. Also, the findings confirmed that both the pressure/volume ratio and the ejection fraction were sensitive to exercise-induced changes in contractility. This demonstration of intrinsic LV contractility in normal subjects, plus the reproducibility of the measurements, supports the feasibility of serial study of LV contractility.

Studies of Left Ventricular Dysfunction (SOLVD) Registry: rationale, design, methods and description of baseline characteristics.

The Studies of Left Ventricular Dysfunction (SOLVD) comprises 2 double-blind, randomized clinical trials to test improved survival by angiotensin-converting enzyme inhibitor in patients with left ventricular dysfunction, with or without congestive heart failure. Patients entering the trials may be a highly selected subset of the population of such patients; those with the worst and best prognosis are likely to be excluded. To obtain the clinical history of a broader group, a registry of 6,273 patients included a relatively unselected cohort of patients with heart failure or left ventricular dysfunction, or both, from SOLVD hospitals. Registry data were obtained from hospital records. Because data collection from medical records may lead to incomplete data and more investigations in "sicker" patients, 898 randomly chosen subjects from different disease strata were seen in clinic where neurohumoral measures, echocardiograms, x-rays and electrocardiograms were obtained, and a 6-minute walking test was performed. The design and methodologic features, and the baseline characteristics of the participants in this 2-tiered registry are described, and its use in complementing the results and interpretation of the SOLVD trials is discussed.

Evaluation of left ventricular performance using digital subtraction angiography.

Cardiac applications for digital subtraction angiography appear promising, but few correlative studies with contrast ventriculography have been done. Left ventricular volume, ejection fraction, and regional wall motion by digital subtraction angiography were evaluated after intravenous injection of 40 ml of iodinated contrast medium and after left ventricular injection of 5 to 10 ml of contrast medium. A film-based system of the authors' own design was used. Results were compared with those after direct left ventricular injection of 40 ml of contrast medium. The ventriculograms after intravenous injection were of diagnostic quality in 9 of 12 studies, and there were close correlations between intravenous and direct-injection studies for left ventricular ejection fraction (r = 0.89, n = 9, and p = 0.001) and for left ventricular volume (r = 0.91, n = 18, and p less than 0.001). Regional wall motion scores showed close correspondence in 83% of sectors. After small-volume left ventricular injections, the ventricular image was enhanced considerably by digital subtraction. Correlations between small- and large-volume ventriculograms were close for left ventricular ejection fraction (r = 0.91, n = 8, and p = 0.002) and for left ventricular volume (r = 0.96, n = 16, and p less than 0.001). There was close correspondence of wall motion scores in 87% of sectors. Thus, digital subtraction angiography improves the visibility of the left ventricle after either intravenous or small-volume direct left ventricular injection. Digital images produce excellent estimates of left ventricular volume and should have considerable usefulness for the study of cardiac performance and anatomy.

Assessment of ventricular size and function in congenitally corrected transposition of the great arteries.

Twenty-four quantitative cineangiographic studies were performed in 19 patients with congenitally corrected transposition of the great arteries to assess right and left ventricular size and function. Ages ranged from 7 days to 44 years and associated lesions included ventricular septal defect (13 of 19), pulmonary stenosis (9 of 19), and systemic (tricuspid) valvular insufficiency (7 of 19). Systemic (anatomically right) ventricular end-diastolic volume was within normal limits in most patients and averaged 119% of predicted normal. Pulmonary (anatomically left) ventricular end-diastolic volume also was normal in most patients, averaged 112% of predicted, and was not different from systemic (right) ventricular end-diastolic volume. Systemic ventricular ejection fraction (RVEF) averaged 0.61 +/- 0.02 and was not different from pulmonary ventricular ejection fraction (LVEF) (0.65 +/- 0.02), but important differences were apparent when age was considered. With exclusion of 2 patients with hypoplastic systemic ventricles and 2 studies performed less than 6 months after open heart surgery, all 12 patients aged less than 10 years had a normal RVEF, whereas 2 of 5 patients aged greater than 17 years had a definitely low RVEF and 1 of 5 had a value at the lower limit of normal. In children, systemic and pulmonary ventricular pump function is usually normal in congenitally corrected transposition of the great arteries and any deviation from normal should suggest ventricular hypoplasia or an increase in afterload. After childhood, systemic ventricular dysfunction is more common and may reflect the inability of the anatomic right ventricle to function as the systemic pumping chamber over a normal lifetime in most patients with congenitally corrected transposition of the great arteries.

Relationship of age with eligibility for thrombolytic therapy and mortality among patients with suspected acute myocardial infarction.

OBJECTIVE: To determine the relationship of age and the percentage of patients presenting to the emergency department with myocardial infarction who meet conventional electrocardiographic and time-to-presentation criteria for thrombolytic therapy. DESIGN: Prospective cohort study. SETTING: Emergency departments of three university hospitals and four community hospitals. PATIENTS: Patients enrolled in the Multicenter Chest Pain Study, an investigation of patients aged 30 years or older presenting to the emergency department with the chief complaint of anterior, precordial, or left lateral chest pain unexplained by obvious local trauma or abnormalities on the chest radiograph. INTERVENTIONS: None. MEASUREMENTS: The frequency of patients who presented with conventional electrocardiographic and time-to-presentation criteria for thrombolysis. MAIN RESULTS: Of a total of 12,140 patients who were enrolled in the Multicenter Chest Pain Study, 10,850 had information about their electrocardiogram and their time-to-presentation. Acute myocardial infarction occurred in 1,584 patients, 746 of whom were over age 65. Among patients presenting to the emergency department with acute myocardial infarction, the proportion who arrived within 6 hours of the onset of pain and had ST-segment elevation or pathologic Q-waves not known to be old decreased significantly with increasing age, from 34% in patients under 65 years to 18% for those 75 years and older. In addition, comorbidities that would have contraindicated thrombolytic therapy were present in an additional 12% of myocardial infarction patients who were older than 65 years. CONCLUSION: Although other analyses have shown that thrombolytic therapy is cost-effective for eligible elderly patients with acute myocardial infarction, only a small percentage of very elderly patients who present to the emergency department with acute myocardial infarctions meet current eligibility criteria to receive it, so thrombolysis is unlikely to narrow the difference in mortality rates for young as compared with elderly patients with acute infarctions.

Severe stenosis of the left main coronary artery with endarterectomy and graft: 33-year follow-up.

In 1964, a patient with symptomatic, severe left main coronary artery stenosis underwent operative treatment. Endarterectomy and pericardial patch grafting were performed successfully. The original operation is described, and the 33-year follow-up is provided.

Early operative intervention in aortic bacterial endocarditis.

Since 1974, 14 patients have required valve replacement for native aortic valve bacterial endocarditis at Vanderbilt University Medical Center. There were 7 male and 7 female patients ranging from 11 to 65 years old. Nine of the patients were less than 27 years old. All patients had congestive heart failure as a complication of the bacterial endocarditis and were in New York Heart Association (NYHA) Functional Class III or IV. Two patients were seen initially with arrhythmias, 3 had episodes of septic emboli, and 1 patient was operated on immediately after sustaining a cardiac arrest. Echocardiogram was utilized in 9 patients, and cardiac catheterization was performed in 6 patients who were suspected to have concomitant mitral valve or coronary artery disease. All patients were operated on within two weeks after the institution of antibiotic therapy, and there were no operative or early postoperatively deaths. Preoperative blood cultures were positive in 13 patients, with streptococcus cultured in 6 patients and staphylococcus in 4. Escherichia coli and enterococcus were the other pathogens cultured. All patients received antibiotics intravenously for a total of six weeks. There has been 1 late postoperative death, which occurred 2 months following operation in a patient with myocardial failure unresponsive to treatment. Two patients underwent reoperation, 1 because of a persistent aorto-right ventricular fistula and the second because of paraprosthetic aortic regurgitation. Nine patients are now in NYHA Functional Class I and 4 are in Class II.