Adv. Cardiol., vol. 20, pp. 54-71 (Karger, Basel 1977)
Automated Data Processing An Essential Decision-Making Aid in the Treatment of Acute Myocardial Infarction PETER
B. CORR and
BURTON
E. SOBEL
Cardiovascular Division, Washington University School of Medicine, St. Louis, Mo.
During the past several years, automated data processing has become increasingly important in the assessment and management of patients with acute myocardial infarction. In this selective summary, we shall briefly consider four applications including: (1) non-invasive assessment of left ventricular function by radionuclide angiocardiography; (2) enzymatic estimation and projection of infarct size; (3) quantification of jeopardized myocardium by positron emission transaxial tomography, and (4) quantification and characterization of ventricular dysrhythmias. One common denominator shared by these approaches is their dependence on automated data processing. In addition, each has facilitated evaluation and management of patients acutely ill with ischemic heart disease.
Utilization of contrast media for measurement of ventricular volume, ejection fraction, and fiber shortening velocity facilitates assessment of ventricular performance. However, serial studies in seriously ill patients are impractical because of the requirement for cardiac catheterization and the potentially deleterious effects of the media on myocardial function. Ventricular performance is a useful index of prognosis after infarction. Furthermore, judicious therapy is designed to maintain ventricular function without unnecessary augmentation of myocardial oxygen requirements. Thus, noninvasive, serial assessments of ventricular performance are likely to be particularly useful in patients with acute myocardial infarction. Several years ago, in collaboration with ASHBURN and co-workers, we
Downloaded by: University of Cambridge 131.111.164.128 - 1/31/2019 6:23:46 PM
Evaluation of Left Ventricular Function
CORRjSOBEL
56
storage oscilloscope and photographed. In our initial study, left ventricular end-systolic and end-diastolic volume were calculated by planimetry of the photographed images. In patients undergoing cardiac catheterization in whom biplane cineangiograms were available, ejection fractions calculated by contrast medium and isotope angiocardiography correlated closely (r = 0.94, n = 15). Furthermore, ventricular wall motion abnormalities were detectable by both techniques. Among 64 patients with acute myocardial infarction, abnormal wall motion was detected by isotope angiocardiography in 47 and verified in every case by radarkymography. Ejection fraction calculated from initial radioisotope angiocardiograms correlated with infarct size estimated enzymatically (r = - 0.73, n = 41), and a low ejection fraction portended increased mortality [2]. Despite the fact that contrast medium ventriculography affords better resolution than isotope angiocardiography after peripheral venous injection of the tracer, the radioisotope technique provides objective evidence characterizing ventricular performance and is suitable for serial studies (fig. I). With the use of a computer to analyze count rates as a function of time in a selected region of interest during the first transit of the radiopharmaceutical, or to calculate total left ventricular end-systolic and end-diastolic counts during equilibrium radiopharmaceutical distribution, ejection fraction can be assessed without resort to planimetry of visualized ventricular images. However, the isotope angiocardiogram is particularly useful in detecting wall motion abnormalities and mitral regurgitation as well.
Traditionally, infarct size has been estimated morphologically in experimental animals, but temporal and morphological disparity of infarcts and inapplicability of sampling techniques to patients limits this approach in the clinical setting. Accordingly, we sought to quantify the extent of injury with the use of a biochemical marker [3]. After coronary occlusion in rabbits, infarct size correlated with CPK depletion from the heart [4]. 24 h after coronary occlusion in dogs, regional CPK depletion correlated with both the extent of infarction demonstrable microscopically [5] and the diminution of blood flow detected from radioactively labeled microspheres [6]. Subsequently, we found that serial changes in plasma CPK activity in conscious dogs subjected to coronary occlusion, analyzed with a simple mathematical model, provided estimates of the amount of CPK lost from the canine heart
Downloaded by: University of Cambridge 131.111.164.128 - 1/31/2019 6:23:46 PM
Enzymatic Estimation of Infarct Size
CaRR/SOBEL
55
performed radioisotope angiocardiograms in patients with acute myocardial infarction with 99mTc sodium pertechnatate injected intravenously [1,2]. Angiocardiograms were obtained with an anger camera equipped with a 4,OOO-parallel hole, low-energy collimator, and scintillation-camera image data were recorded on magnetic tape. With this technique, gating of the image can be achieved electronically or with the use of a computer, and images at end-systole or end-diastole can be summed and displayed on a
Downloaded by: University of Cambridge 131.111.164.128 - 1/31/2019 6:23:46 PM
Fig. I. A radioisotope angiocardiogram obtained in a patient with acute myocardial infarction. Autologous 99mTc-labe\ed red cells were prepared electrolytically and injected intravenously at the time of the study. This technique offers some advantages for serial studies in comparison to the use of 99mTc-albumin because of increased persistence of the tracer within the circulation. As can be seen, the left ventricle (LV) is differentiated effectively from the right atrium (RA) and right ventricle (R V) in this electrocardiographically gated diastolic image.
Automated Data Processing
57
200 180 160 140
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120
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Automated Data Processing An Essential Decision-Making Aid in the Treatment of Acute Myocardial Infarction PETER
B. CORR and
BURTON
E. SOBEL
Cardiovascular Division, Washington University School of Medicine, St. Louis, Mo.
During the past several years, automated data processing has become increasingly important in the assessment and management of patients with acute myocardial infarction. In this selective summary, we shall briefly consider four applications including: (1) non-invasive assessment of left ventricular function by radionuclide angiocardiography; (2) enzymatic estimation and projection of infarct size; (3) quantification of jeopardized myocardium by positron emission transaxial tomography, and (4) quantification and characterization of ventricular dysrhythmias. One common denominator shared by these approaches is their dependence on automated data processing. In addition, each has facilitated evaluation and management of patients acutely ill with ischemic heart disease.
Utilization of contrast media for measurement of ventricular volume, ejection fraction, and fiber shortening velocity facilitates assessment of ventricular performance. However, serial studies in seriously ill patients are impractical because of the requirement for cardiac catheterization and the potentially deleterious effects of the media on myocardial function. Ventricular performance is a useful index of prognosis after infarction. Furthermore, judicious therapy is designed to maintain ventricular function without unnecessary augmentation of myocardial oxygen requirements. Thus, noninvasive, serial assessments of ventricular performance are likely to be particularly useful in patients with acute myocardial infarction. Several years ago, in collaboration with ASHBURN and co-workers, we
Downloaded by: University of Cambridge 131.111.164.128 - 1/31/2019 6:23:46 PM
Evaluation of Left Ventricular Function
CORRjSOBEL
56
storage oscilloscope and photographed. In our initial study, left ventricular end-systolic and end-diastolic volume were calculated by planimetry of the photographed images. In patients undergoing cardiac catheterization in whom biplane cineangiograms were available, ejection fractions calculated by contrast medium and isotope angiocardiography correlated closely (r = 0.94, n = 15). Furthermore, ventricular wall motion abnormalities were detectable by both techniques. Among 64 patients with acute myocardial infarction, abnormal wall motion was detected by isotope angiocardiography in 47 and verified in every case by radarkymography. Ejection fraction calculated from initial radioisotope angiocardiograms correlated with infarct size estimated enzymatically (r = - 0.73, n = 41), and a low ejection fraction portended increased mortality [2]. Despite the fact that contrast medium ventriculography affords better resolution than isotope angiocardiography after peripheral venous injection of the tracer, the radioisotope technique provides objective evidence characterizing ventricular performance and is suitable for serial studies (fig. I). With the use of a computer to analyze count rates as a function of time in a selected region of interest during the first transit of the radiopharmaceutical, or to calculate total left ventricular end-systolic and end-diastolic counts during equilibrium radiopharmaceutical distribution, ejection fraction can be assessed without resort to planimetry of visualized ventricular images. However, the isotope angiocardiogram is particularly useful in detecting wall motion abnormalities and mitral regurgitation as well.
Traditionally, infarct size has been estimated morphologically in experimental animals, but temporal and morphological disparity of infarcts and inapplicability of sampling techniques to patients limits this approach in the clinical setting. Accordingly, we sought to quantify the extent of injury with the use of a biochemical marker [3]. After coronary occlusion in rabbits, infarct size correlated with CPK depletion from the heart [4]. 24 h after coronary occlusion in dogs, regional CPK depletion correlated with both the extent of infarction demonstrable microscopically [5] and the diminution of blood flow detected from radioactively labeled microspheres [6]. Subsequently, we found that serial changes in plasma CPK activity in conscious dogs subjected to coronary occlusion, analyzed with a simple mathematical model, provided estimates of the amount of CPK lost from the canine heart
Downloaded by: University of Cambridge 131.111.164.128 - 1/31/2019 6:23:46 PM
Enzymatic Estimation of Infarct Size
CaRR/SOBEL
55
performed radioisotope angiocardiograms in patients with acute myocardial infarction with 99mTc sodium pertechnatate injected intravenously [1,2]. Angiocardiograms were obtained with an anger camera equipped with a 4,OOO-parallel hole, low-energy collimator, and scintillation-camera image data were recorded on magnetic tape. With this technique, gating of the image can be achieved electronically or with the use of a computer, and images at end-systole or end-diastole can be summed and displayed on a
Downloaded by: University of Cambridge 131.111.164.128 - 1/31/2019 6:23:46 PM
Fig. I. A radioisotope angiocardiogram obtained in a patient with acute myocardial infarction. Autologous 99mTc-labe\ed red cells were prepared electrolytically and injected intravenously at the time of the study. This technique offers some advantages for serial studies in comparison to the use of 99mTc-albumin because of increased persistence of the tracer within the circulation. As can be seen, the left ventricle (LV) is differentiated effectively from the right atrium (RA) and right ventricle (R V) in this electrocardiographically gated diastolic image.
Automated Data Processing
57
200 180 160 140
i:: u
120
OJ
:;: 100 E o
