Quantitative exercise thallium-201 rotational tomography for evaluation of patients with prior myocardial infarction.

The utility of stress-redistribution thallium-201 myocardial perfusion single-photon emission computed tomography (SPECT) in patients with a prior single myocardial infarction was studied in 66 patients who were tested by both SPECT and coronary angiography. SPECT was quantified by comparing the patients' circumferential count profiles to a previously established normal data base and by plotting the results onto a polar coordinate map that localized defects to the 3 major coronary artery territories. The pattern of reversibility of the quantitatively detected defects was assessed by consensus visual analysis. SPECT thallium-201 detected myocardial infarction in 62 of 66 patients (sensitivity = 94%). Sixty-five percent of the infarct zones showed some reversibility at 4-hour imaging which corresponded with angiographic evidence of flow to the infarct zones in 95.5% of cases. Late (18 to 24 hours) imaging, done in 26 patients, showed complete or partial reversibility of 29% of infarct zone segments which were nonreversible on 4-hour images. To improve specificity for detection of disease in coronary arteries supplying the non-infarct territories, new quantitative criteria were developed that took into consideration contiguity of defects with the infarct zone. Accuracy for detection of patients with multivessel coronary disease by quantitative thallium-201 SPECT was 86%, which was significantly higher than those of the clinical response to exercise (48%), the exercise electrocardiographic response (56%) or their combination (65%).(ABSTRACT TRUNCATED AT 250 WORDS)

Quantification of left ventricular myocardial mass in humans by nuclear magnetic resonance imaging.

The ability of NMRI to assess LV mass was studied in 20 normal males. By means of a 1.5 Tesla GE superconducting magnet and a standard spin-echo pulse sequence, multiple gated short-axis and axial slices of the entire left ventricle were obtained. LV mass was determined by Simpson's rule with the use of a previous experimentally validated method. The weight of the LV apex (subject to partial volume effect in the short-axis images) was derived from axial slices and that of the remaining left ventricle from short-axis slices. The weight of each slice was calculated by multiplying the planimetered surface area of the LV myocardium by slice thickness and by myocardial specific gravity (1.05). Mean +/- standard deviation of LV mass and LV mass index were 146 +/- 23.1 gm (range 92.3 to 190.4 gm) and 78.4 +/- 7.8 gm/m2 (range 57.7 to 89.4 gm/m2), respectively. Interobserver agreement as assessed by ICC was high for determining 161 individual slice masses (ICC = 0.99) and for total LV mass (ICC = 0.97). Intraobserver agreement for total LV mass was also high (ICC = 0.96). NMRI-determined LV mass correlated with body surface area: LV mass = 55 + 108 body surface area, r = 0.83; with body weight: LV mass = 26 + 0.77 body weight, r = 0.82; and with body height: LV mass = 262 +/- 5.9 body height, r = 0.75. Normal limits were developed for these relationships. NMRI-determined LV mass as related to body weight was in agreement with normal limits derived from autopsy literature data.(ABSTRACT TRUNCATED AT 250 WORDS)

Paradoxical motion of the posterior left ventricular wall seen in healthy subjects in the upright position.

Paradoxical motion of the posterior left ventricular wall in patients in the upright but not in the supine position was demonstrated in a high percentage of normal volunteers. There was no significant difference in age, body surface area, heart rate, and blood pressure between the groups, with or without paradoxical motion. This echocardiographic finding probably represents a physiologic phenomenon and should be taken into consideration during the interpretation of upright exercise echocardiograms.

Piretanide, a potent diuretic with potassium-sparing properties, for the treatment of congestive heart failure.

The diuretic and clinical efficacy and safety of piretanide, a new high-ceiling loop diuretic, was determined in patients with mild to moderately severe congestive heart failure. Piretanide (n = 20) administered orally in a daily dosage of up to 24 mg was compared with placebo (n = 18) for 28 days, using a double-blind, randomized, parallel design. Patients were hospitalized during the first 5 days of the study when dosage titration was established and 24-hour fractionated urine collections were obtained. Piretanide caused significant diuresis for 3 hours after ingestion with a natriuretic response noted for up to 6 hours. While occasional kaliuretic response was noted, it did not significantly increase 24-hour urinary potassium excretion. Only one patient treated with the highest allowed dose of piretanide developed mild hypokalemia. An improvement in New York Heart Association functional class status was noted after piretanide therapy. In contrast, patients who received placebo exhibited no significant improvement. BUN increased in nine piretanide-treated patients; two were discontinued from the study because of progressive azotemia. However, there was no significant increase in serum creatinine levels. Other blood, physical, ECG, and audiometric examinations also revealed no significant abnormalities. The study suggests that oral piretanide is a relatively safe and effective diuretic for treating congestive heart failure with a potential advantage of having potassium-sparing properties.

Utility of echocardiography for the early assessment of patients with nondiagnostic chest pain.

A two-dimensional (2D) echocardiogram was recorded shortly after admission in 46 patients with nondiagnostic chest pain. Eighteen patients were studied during chest pain and 28 were studied following the resolution of chest pain. Of the 18 patients studied during chest pain, six of the eight patients who had a regional wall motion abnormality (RWMA) evolved an acute infarction and the remaining two patients had evidence of significant coronary artery disease. Only 1 of 10 patients without a RWMA evolved an infarction and none had significant coronary artery disease. Of the 28 patients studied following the resolution of chest pain, 8 of the 10 patients with a RWMA evolved an acute infarction and one patient had evidence of significant coronary artery disease, whereas of 18 patients without a RWMA, none evolved an acute infarction and five had evidence of significant coronary artery disease. These data suggest that in patients presenting with nondiagnostic chest pain, an early assessment of regional wall motion by 2D echocardiography can reliably differentiate patients with myocardial ischemia or early infarction from patients with nonischemic chest pain when performed during an episode of chest pain; can also identify those patients with early acute myocardial infarction, even when performed following the resolution of chest pain; but is not useful for the detection of patients with significant coronary artery disease without infarction when performed following the resolution of chest pain.

Intravenous streptokinase in evolving acute myocardial infarction.

Eighty-one consecutive patients presenting within 3 hours of the onset of acute myocardial infarction (AMI) and without contraindications to thrombolytic or anticoagulant therapy received a 15- to 30-minute intravenous infusion of 750,000 or 1.5 million units of streptokinase (STK) followed by anticoagulation. Treatment was instituted 130 +/- 41 minutes after the onset of symptoms and reperfusion was achieved 36 +/- 26 minutes later. Reperfusion of the "infarct artery" was recognized by indirect clinical criteria in 78 patients (96%). In all 66 patients who underwent coronary angiography 3 to 7 days later, there was complete concordance between indirect and angiographic evidence of reperfusion. In 6 patients there was early reocclusion within 24 hours of treatment; in 4 of these patients, the artery was reopened with an additional dose of STK. Two elderly patients suffered an intracranial hemorrhage and there were 8 other major hemorrhagic complications, of which 7 were related to procedural trauma. Five patients (6.2%) died in the hospital. The results of intravenous STK thrombolytic therapy are compared with those of our previous study using intracoronary STK.

Improvement in regional and global left ventricular function after intracoronary thrombolysis: assessment with two-dimensional echocardiography.

After acute myocardial infarction, 23 patients undergoing intracoronary thrombolysis and 10 patients receiving conventional medical treatment were studied by 2-dimensional echocardiography to determine changes in regional and global left ventricular (LV) performance. Both quantitative and qualitative analysis of echocardiographic studies showed improvement in regional and global LV function in 18 patients with successful reperfusion immediately after thrombolysis to 10 days later (p less than 0.0005). Eleven patients who were studied before thrombolysis demonstrated no change in regional or global LV function immediately after thrombolysis. LV function did not improve in the conventionally treated group. These data indicate that in patients with acute coronary artery occlusion successfully reperfused by intracoronary thrombolysis, regional and global LV function improved by day 10 but not immediately after reperfusion.

Simultaneous assessment of segmental and global left ventricular function by two-dimensional echocardiography in acute myocardial infarction.

Both segmental and global left ventricular performance were assessed simultaneously in 29 patients with acute myocardial infarction using two-dimensional echocardiography. Comparisons were made between left ventricular wall motion versus peak CK-MB, site of infarction, and occurrence of heart failure. Two-dimensional echocardiography identified areas of dyssynergy which corresponded to electrocardiographic areas of infarction in 89% of all cases. Patients with heart failure had more dyssynergic segments, and these segments manifested more severe dyssynergy than patients without heart failure. Patients with severe global dysfunction manifested higher peak CK-MB values, and those with anterior infarction had more global dyssynergy than did those patients with inferior infarction. These observations suggest that two-dimensional echocardiography is a useful technique for localization and assessment of segmental and global dyssynergy in acute myocardial infarction. Information so derived correlates with the clinical status of patients with acute myocardial infarction, and may offer important insights into both prognosis and treatment.

Nonsurgical reperfusion in evolving myocardial infarction.

Nonsurgical recanalization of the occluded coronary artery has been performed in patients with evolving myocardial infarction since the late 1970s by intracoronary administration of thrombolytic agents at the ostium of the occluded artery or directly to the site of occlusion. The authors review the basic concepts underlying intracoronary thrombolysis, the method applied at their institution and the clinical results. Reperfusion of totally occluded arteries or termination of the ischemic state in subtotally occluded arteries was achieved in 71 (87.7%) of 81 patients. Reocclusion occurred in four patients, in three of these at a time when anticoagulation became temporarily ineffective, emphasizing the need for uninterrupted anticoagulation with a partial thromboplastin time longer than 80 seconds. Thallium scintigraphic studies before and after reperfusion showed a decrease in defect, indicating myocardial salvage, in the successful cases but not in failures or untreated control subjects. A decrease in thallium-201 defect was followed by improvement of regional wall motion and usually also left ventricular ejection fraction. Three of the patients with an unsuccessful result and one patient with a successful result died. Bypass surgery was performed electively in 18 patients because of multiple vessel involvement. Intracoronary thrombolysis appears to be a relatively safe and promising procedure. A large controlled study will be needed for definitive assessment of its role in the management of acute myocardial infarction.

Early diagnosis of nontransmural myocardial infarction by two-dimensional echocardiography.

Thirty patients with chest pain syndromes were studied on admission by two-dimensional echocardiography (2DE) to confirm or exclude acute myocardial infarction (AMI). Twelve patients suffered nontransmural AMI and 18 patients had no AMI. There was no significant difference between these groups in background characteristics. 2DE studies were analyzed quantitatively and qualitatively. The most sensitive and specific technique for detecting AMI was qualitative analysis, using the presence of severe hypokinesis as the criterion for an abnormal study. Using this technique, 10 of 12 patients (83%) with AMI and all 18 patients (100%) without AMI were correctly identified. This analysis technique was highly reproducible. These data indicate that in patients with chest pain syndromes without diagnostic ECG findings of AMI, 2DE may provide a rapid, sensitive, specific tool to aid in the establishment of the correct diagnosis. In patients with nontransmural AMI, the presence of severe hypokinesis appears to be the best discriminator of myocardial infarction.

Intracoronary thrombolysis in acute myocardial infarction: experimental background and clinical experience.

Occlusive intracoronary (IC) thrombosis was produced experimentally in dogs by placement of a copper coil. The thrombus was consistently lysed by application of Thrombolysin (streptokinase and plasminogen) at the site of occlusion, 1 to 6 hours after thrombosis. Thrombolysin has no toxic effect on the coronary artery wall or the myocardium. Reperfusion after 30 to 60 minutes of occlusion frequently resulted in ventricular fibrillation, but gradual reperfusion reduced the probability of ventricular fibrillation. Intramyocardial bleeding was noted after reperfusion in areas of advanced necrosis and was shown to be the consequence, rather than the cause, of necrosis. The reperfused myocardium remained hypocontractile, but in contrast to the occlusion period, its mechanical function could be enhanced by inotropic stimulation. After experimental studies confirmed the feasibility and safety of IC thrombolysis, the technique was applied within 3 hours of onset of pain in 29 patients with evolving acute myocardial infarction (AMI) and showing ST elevations without pathologic Q waves. Nitroglycerin (NTG), 0.1 mg, was injected into the occluded coronary artery to rule out spasm; NTG failed to open the occluded artery. A special, very flexible, radiopaque No. 2 French catheter was advanced through the angiography catheter to the site of occlusion. Thrombolysin was infused at a rate of 4000 to 6000 IU/min until patency was achieved, followed by 2000 IU/min for 60 minutes. Lysis of clot was achieved in 27 of 29 patients. The single death (unrelated to the procedure) occurred subsequently in a patient in whom the artery was not reopened. After successful thrombolysis, 12 patients underwent elective coronary bypass surgery because of multiple stenoses. The need for early reperfusion is emphasized for effective IC thrombolysis therapy in evolving AMI.

Relationship between segmental abnormalities and global left ventricular function in coronary artery disease: validation of a theoretical model.

A theoretical model of the heart, which suggests a direct relationship between segmental abnormalities of left ventricular (LV) wall motion (WM) and LV ejection fraction (EF), was tested using two-dimensional echocardiography (2DE) and multiple-gated equilibrium blood pool scintigraphy (MGES) in a population of 25 coronary artery disease patients. MGES was used to determine EF, and 2DE was used to develop a method of analysis of LV segmental WM abnormalities. Two orthogonal apical 2DE views were analyzed. The length of the end-diastolic segments in which normal contraction occurred during systole were measured in each view, summed and divided by the sum of the end-diastolic silhouette lengths. The fraction thus created was multiplied by 100 and defined as the percentage of normally contracting myocardium (%NCM). %NCM correlated well with EF determined by MGES (r = 0.94). Determination of %NCM was highly reproducible for the same observer (r = 0.98), as well as for two observers (r = 0.98), and the standard error of estimate was low in both cases (4%). These findings, in addition to confirming the theoretical model, provide a new technique to assess LV segmental WM abnormalities by 2DE.