DOCSLIB.ORG

Computer Processing of the Orthogonal Electrocardiogram and Vectorcardiogram

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Computer Processing of the Orthogonal Electrocardiogram and Vectorcardiogram Physiol. Res. 43: 95-98, 1993 Computer Processing of the Orthogonal Electrocardiogram and Vectorcardiogram L. BACHÂROVÀ Research Institute of Medical Informatics, Bratislava Summary The aim of this contribution was to review the possibilities of presentation of orthogonal ECG signals and to evaluate the progress in computerized electrocardiography achieved in Czechoslovakia. The information about the cardiac electric field in orthogonal electrocardiography is defined and consequently displayed as a fixed single dipole (vector). The spatial trajectory of vector end-point (spatial vectorcardiographic loop) can be presented in different ways — as orthogonal electrocardiogram, polarcardiogram, planar vectorcardiogram and decartogram, respectively. The advantages of particular methods of presentation, as well as their limitations are discussed. Computer-assisted electrocardiography was introduced in Czechoslovakia in 1974. The original AVA program has been further developed in the Research Institute of Medical Informatics (formerly Research Institute of Medical Bionics). The currently developed system CardioSys allows the utilization of all the possibilities of orthogonal ECG and vectorcardiographic presentation for clinical and epidemiological cardiology as well as for the research. Key words Orthogonal Electrocardiography - Vectorcardiography - Computer analysis The electrographic signal provides are the physiological source of electrocardiographic irreplaceable information about the status and activity potentials. The front of myocardial depolarization is in of the heart. In current clinical practice, it is mostly fact an electrical double-layer and, as such, may be registered by means of a standard 12-lead ECG system. represented by a set of regularly spaced unit vectors. However, the information obtained in this way is The vectorial sum of these unit vectors gives the characterized by a considerable redundancy. instantaneous cardiac vector, which is recorded as an Orthogonal physically corrected electrocardiographic instantaneous vectorcardiographic vector by means of lead systems have the following advantages with appropriate physically corrected lead systems (Frank respect to the standard 12-lead ECG (Ruttkay- 1956, McFee and Parungao 1961, Laulberger 1965). Nedeckÿ 1983): a) they do not contain redundant The trajectory of the end-points of these instantaneous information, so that manual evaluation as well as vectors in space results in the spatial computer processing of ECG is more efficient, b) vectorcardiographic loop. While distinct activation spatial presentation in the X, Y, Z coordinate system fronts may be experimentally recorded in the is in accordance with the usual description of the myocardium of atria and ventricles during patients body, as for example on X-ray or physical depolarization, the situation during the repolarization examination, c) the information content of orthogonal period is more complicated because of spatial ECG is not smaller than that of the standard 12-lead dispersion of boundaries between areas of the ECG, d) the relations between individual leads can be myocardium with different levels of repolarization. determined in more detail and visualized. This The crucial problem of non-invasive advantage is provided by vectorcardiography. assessment of the cardiac electric field is to find how to The aim of this contribution was to review the express the underlying physiological events in the possibilities of displaying orthogonal ECG signals and myocardium of body surface potential measurements in to evaluate the progress in computerized a meaningful and quantitative manner. electrocardiography achieved in the Czech and Slovak Hitherto, the best and most rational solution is Republics. spatial vectorcardiography (Rijlant 1956, Laulberger The temporospatial distribution of myocardial 1965, Kowarzyk et at. 1970). activation fronts and the pattern of this repolarization 96 Bachérovâ Vol. 42 The spatial trajectory of vector end-points cardiologic health programs since it was found that (spatial vectorcardiographic loop) can be defined and computer processing of physically corrected orthogonal presented in the following ways: ECG leads was more rational and more apt for further 1. Orthogonal electrocardiograms represent the time development. The AVA software was implemented functions of X,Y,Z rectangular coordinates of spatial into home produced computers and a series of ECG vector end-points. Their presentation and evaluated apparatuses produced by Chirana (Prague) was parameters (amplitudes and time intervals of adapted for this purpose. P,Q,R,S,T waves) are the same as in standard 12-lead The diagnostic efficiency of the AVA electrocardiography, so they are easily acceptable for interpretative program, based on vectorial analysis of users who are familiar with the rational evaluation of the orthogonal 3-lead ECG signals, was repeatedly standard 12-lead ECGs. Furthermore, orthogonal reevaluated (Table 1) electrocardiograms are needed for the study of cardiac arrhythmias. Table 1 2. Polarcardiograms describe the spatial magnitude Brief summary of diagnostic evaluation of AVA (module) and spatial orientation of vector end-points program in Czechoslovakia giving year of evaluation, as a time course of polar coordinates, e.g. spatial computer employed, reference electrocardiologic magnitude, azimuth and elevation. The method and % of false positive (FP) and false negative polarcardiogram provides a good description of the (FN) findings trajectory in space. However, in both cases we obtain the time courses of three coordinates and their mutual 1976 HP 2100, compared to 12-lead ECG relationships at any given instant are difficult to (Ruttkay-Nedeckÿ) FP 33.1 % FN 7.7 % identify. 3. This problem is solved by vectorcardiography. Planar 1982 RPP 16, compared to 12-lead ECG vectorcardiograms are the planar projections of the (Renker et al.) FP 34.7 % FN 2.9 % spatial vectorcardiographic loop onto three planes perpendicular to each other - frontal, sagital and 1988 SM 4-20, compared to VCG horizontal. This presentation is very instrumental for (Bachârovâ et al.) FP 10.1 % FN 4.5 % visualization of activation front sequence, and provides a broad spectrum of two- and three-dimensional parameters. They provide complex detailed The first evaluation of the software information about the spatial localization and implemented on a HP 2100A computer was performed movement of spatial vector end-points. in 1975 (Ruttkay-Nedecky 1976). Full diagnostic 4. Decartograms (as will be described below) visualize agreement with the conclusions of human readers of the sequence of activation as a sequence of activated 12-lead ECG was obtained in 56.5 % of ECGs. False points on a spherical surface closely enveloping the positive conclusions were described in 33.1 %, false heart. The localization of the activated areas negative in 7.7 % (4.3 % incomplete right bundle determined by spatial orientation of the vector, and the branch block, 1.7 % abnormal P wave configurations, extent of the activated area at given instants of time is 1.7 % non-specific ST-T changes). The first proportional to the module of the vector related to the Czechoslovak equipment used for computerized ECG maximum spatial vector magnitude. Decomposition of analysis was a minicomputer RPP 16 combined with an the information about the spatial localization of a electrocardiograph Chirakard 601 TK. A group of 167 vector end-point into the area of defined localization ECGs was analyzed resulting in 34.7 % of false positive and size makes it possible to use advanced and 2.9 % of false negative conclusions as compared to mathematical methods, which is especially important in 12-lead ECG evaluation by cardiologists (Renker et al. the evaluation of normal and borderline pathological 1982). Evaluation of 488 ECGs within the framework findings. of a screening project showed 10.1 % of false positive For practical purposes of preventive and and 4.5 % of false negative conclusions when compared clinical cardiology, different computer-based automatic with the assessment of vectorcardiograms obtained data evaluation and diagnostic programs have been from the same signal by experienced devised. Computer assisted electrocardiography was vectorcardiographers (Bacharov£et al. 1988). introduced in Czechoslovakia in 1974 when the The repeat variability and correlations Research Institute of Medical Bionics in Bratislava was between changes in 16-lead orthogonal Frank ECG equipped with computers allowing the introduction and parameters were examined in 50 healthy subjects, 50 mutual comparison of the 12-lead ECG 5600 patients with left ventricular hypertrophy (LVH) and interpretative system (Baida 1977) and the orthogonal 50 patients with anterior or posterior chronic 3-lead system ECG 1530 B, (AVA interpretative myocardial infarction. The greatest effect on QRS-T system) (Pipberger 1974). At that time, the AVA diagnostic probability was exerted by changes of system was selected for utilization in preventive amplitudes of Ry, Ty, Jy, Rz, time intervals Qx and 1993 Computerized Vectorcardiography 97 QRS in the normal group, amplitudes Rx, Tx, Ty, Jz in the form of discrete spherical image surface in the and Qz duration in patients with LVH, amplitude ratio shape of a rectangle. Q/Ry, Q/Rz and QRS duration in patients with A sample of 123 healthy subjects, originally myocardial infarction. Changes of the probability included in a study of normal vectorcardiographic values could only
Load more

Recommended publications
  • Left Ventricular Wall Findings in Non-Electrocardiography-Gated CE-CT After ECPR Might Be Useful for Diagnosis and Prognostic Prediction
    Sugiyama et al. Critical Care (2019) 23:357 https://doi.org/10.1186/s13054-019-2624-1 RESEARCH Open Access Left ventricular wall findings in non- electrocardiography-gated contrast- enhanced computed tomography after extracorporeal cardiopulmonary resuscitation Kazuhiro Sugiyama1* , Masamichi Takahashi2, Kazuki Miyazaki1, Takuto Ishida1, Mioko Kobayashi1 and Yuichi Hamabe1 Abstract Background: Few studies have reported left ventricular wall findings in contrast-enhanced computed tomography (CE-CT) after extracorporeal cardiopulmonary resuscitation (ECPR). This study examined left ventricular wall CE-CT findings after ECPR and evaluated the association between these findings and the results of coronary angiography and prognosis. Methods: We evaluated out-of-hospital cardiac arrest patients who were treated with ECPR and subsequently underwent both non-electrocardiography-gated CE-CT and coronary angiography at our center between January 2011 and April 2018. Left ventricular wall CE-CT findings were classified as follows: (1) homogeneously enhanced (HE; the left ventricular wall was homogeneously enhanced), (2) segmental defect (SD; the left ventricular wall was not segmentally enhanced according to the coronary artery territory), (3) total defect (TD; the entire left ventricular wall was not enhanced), and (4) others. Successful weaning from extracorporeal membrane oxygenation, survival to hospital discharge, and predictive ability of significant stenosis on coronary angiography were compared among patients with HE, SD, and TD patterns. Results: A total of 74 patients (median age, 59 years) were eligible, 50 (68%) of whom had initial shockable rhythm. Twenty-three (31%) patients survived to hospital discharge. HE, SD, TD, and other patterns were observed in 19, 33, 11, and 11 patients, respectively. The rates of successful weaning from extracorporeal membrane oxygenation (84% vs.
    [Show full text]
  • Sparse-Input Detection Algorithm with Applications in Electrocardiography and Ballistocardiography
    Sparse-input Detection Algorithm with Applications in Electrocardiography and Ballistocardiography ;1 ;1 2 1 1 F. Wadehn∗ , L. Bruderer∗ , D. Waltisberg , T. Keresztfalvi and H.-A. Loeliger 1 Signal and Information Processing Laboratory, ETH Zurich, Gloriastrasse 35, Zurich, Switzerland 2 Institut fuer Elektronik, ETH Zurich, Gloriastrasse 35, Zurich, Switzerland Keywords: Ballistocardiography, Heart Rate Estimation, Hypothesis Test, Factor Graphs, System identification, State- space Models, Maximum likelihood, Maximum a posteriori. Abstract: Sparse-input learning, especially of inputs with some form of periodicity, is of major importance in bio- signal processing, including electrocardiography and ballistocardiography. Ballistocardiography (BCG), the measurement of forces on the body, exerted by heart contraction and subsequent blood ejection, allows non- invasive and non-obstructive monitoring of several key biomarkers such as the respiration rate, the heart rate and the cardiac output. In the following we present an efficient online multi-channel algorithm for estimating single heart beat positions and their approximate strength using a statistical hypothesis test. The algorithm was validated with 10 minutes long ballistocardiographic recordings of 12 healthy subjects, comparing it to synchronized surface ECG measurements. The achieved mean error rate for the heart beat detection excluding movement artifacts was 4:7%. 1 INTRODUCTION Early signal-processing methods for BCG signals (Watanabe et al., 2005; Mack et al., 2009) concerned Cardiovascular diseases are among the leading causes estimation of heart rates averaged over a few sec- of death and severe health impairments both in high- onds using frequency-based methods. These meth- income countries with an aging population, as well ods do not provide beat-to-beat resolution or infor- as in developing countries, which are increasingly mation on irregular arrhythmias.
    [Show full text]
  • 2Nd Quarter 2001 Medicare Part a Bulletin
    In This Issue... From the Intermediary Medical Director Medical Review Progressive Corrective Action ......................................................................... 3 General Information Medical Review Process Revision to Medical Record Requests ................................................ 5 General Coverage New CLIA Waived Tests ............................................................................................................. 8 Outpatient Hospital Services Correction to the Outpatient Services Fee Schedule ................................................................. 9 Skilled Nursing Facility Services Fee Schedule and Consolidated Billing for Skilled Nursing Facility (SNF) Services ............. 12 Fraud and Abuse Justice Recovers Record $1.5 Billion in Fraud Payments - Highest Ever for One Year Period ........................................................................................... 20 Bulletin Medical Policies Use of the American Medical Association’s (AMA’s) Current Procedural Terminology (CPT) Codes on Contractors’ Web Sites ................................................................................. 21 Outpatient Prospective Payment System January 2001 Update: Coding Information for Hospital Outpatient Prospective Payment System (OPPS) ......................................................................................................................... 93 he Medicare A Bulletin Providers Will Be Asked to Register Tshould be shared with all to Receive Medicare Bulletins and health care
    [Show full text]
  • Electrocardiography: a Technologist's Guide to Interpretation
    CONTINUING EDUCATION Electrocardiography: A Technologist’s Guide to Interpretation Colin Tso, MBBS, PhD, FRACP, FCSANZ1,2, Geoffrey M. Currie, BPharm, MMedRadSc(NucMed), MAppMngt(Hlth), MBA, PhD, CNMT1,3, David Gilmore, ABD, CNMT, RT(R)(N)3,4, and Hosen Kiat, MBBS, FRACP, FACP, FACC, FCCP, FCSANZ, FASNC, DDU1,2,3,5 1Faculty of Medicine and Health Sciences, Macquarie University, Sydney, New South Wales, Australia; 2Cardiac Health Institute, Sydney, New South Wales, Australia; 3Faculty of Science, Charles Sturt University, Wagga Wagga, New South Wales, Australia; 4Faculty of Medical Imaging, Regis College, Boston, Massachusetts; and 5Faculty of Medicine, University of New South Wales, Sydney, New South Wales, Australia CE credit: For CE credit, you can access the test for this article, as well as additional JNMT CE tests, online at https://www.snmmilearningcenter.org. Complete the test online no later than December 2018. Your online test will be scored immediately. You may make 3 attempts to pass the test and must answer 80% of the questions correctly to receive 1.0 CEH (Continuing Education Hour) credit. SNMMI members will have their CEH credit added to their VOICE transcript automatically; nonmembers will be able to print out a CE certificate upon successfully completing the test. The online test is free to SNMMI members; nonmembers must pay $15.00 by credit card when logging onto the website to take the test. foundation for understanding the science of electrocardiog- The nuclear medicine technologist works with electrocardio- raphy and its interpretation. graphy when performing cardiac stress testing and gated cardiac imaging and when monitoring critical patients.
    [Show full text]
  • Early Or Delayed Cardioversion in Recent-Onset Atrial Fibrillation
    The new england journal of medicine Original Article Early or Delayed Cardioversion in Recent-Onset Atrial Fibrillation N.A.H.A. Pluymaekers, E.A.M.P. Dudink, J.G.L.M. Luermans, J.G. Meeder, T. Lenderink, J. Widdershoven, J.J.J. Bucx, M. Rienstra, O. Kamp, J.M. Van Opstal, M. Alings, A. Oomen, C.J. Kirchhof, V.F. Van Dijk, H. Ramanna, A. Liem, L.R. Dekker, B.A.B. Essers, J.G.P. Tijssen, I.C. Van Gelder, and H.J.G.M. Crijns, for the RACE 7 ACWAS Investigators*​​ ABSTRACT BACKGROUND Patients with recent-onset atrial fibrillation commonly undergo immediate restora- The authors’ full names, academic degrees, tion of sinus rhythm by pharmacologic or electrical cardioversion. However, whether and affiliations are listed in the Appen- dix. Address reprint requests to Dr. Crijns immediate restoration of sinus rhythm is necessary is not known, since atrial fibril- at the Department of Cardiology, Maas- lation often terminates spontaneously. tricht University Medical Center, P. Debye- laan 25, 6229 HX Maastricht, the Nether- METHODS lands, or at hjgm . crijns@ mumc . nl. In a multicenter, randomized, open-label, noninferiority trial, we randomly assigned *A complete list of investigators in the patients with hemodynamically stable, recent-onset (<36 hours), symptomatic atrial RACE 7 ACWAS trial is provided in the fibrillation in the emergency department to be treated with a wait-and-see approach Supplementary Appendix, available at (delayed-cardioversion group) or early cardioversion. The wait-and-see approach in- NEJM.org. volved initial treatment with rate-control medication only and delayed cardioversion Drs.
    [Show full text]
  • Guide to Exercise Electrocardiogram
    Guide to the Exercise Electrocardiogram (The Treadmill Stress Test) An exercise stress test is performed to evaluate heart rate, heart rhythm, blood pressure and electrocardiographic (ECG) responses to progressive exercise. You do not need to be an athlete or to be trained to have this test for evaluation of your cardiovascular system, but you do need to be able to walk without support. The exercise ECG is used to evaluate the adequacy of blood supply to the heart during exercise that may be symptomatic or asymptomatic and to assess the extent of limitation of blood supply to the heart in people with known coronary artery disease. The test is also used to quantify effort capacity, to evaluate the effect of medications on symptoms and effort tolerance, to assess general health and prognosis, and to evaluate the heart rate and blood pressure responses to exercise before surgical procedures and before entry into programs of cardiac rehabilitation. Imaging of the heart with echocardiography or with radionuclide agents is not performed during basic exercise ECG unless prearranged by the referring physician. Pre-Registration and Testing Location Please call 2 days before the date your test is scheduled to confirm your appointment. At this time we can also answer questions you may have. Please have your referring physician complete the order form. Plan to arrive 20 minutes before the scheduled time of your test. Bring your hospital and insurance cards with you. Go directly to the test location. NewYork-Presbyterian Hospital/Weill Cornell Medical Center 212-746-4670 Exercise ECG Laboratory Starr Pavilion 520 East 70th Street, east of York Avenue New York, NY 10021 Take the Starr elevators to the 4th floor, follow the signs to room K-425.
    [Show full text]
  • Echocardiography to Supplement Stress Electrocardiography in Emergency Department Chest Pain Patients
    Original research Echocardiography to Supplement Stress Electrocardiography in Emergency Department Chest Pain Patients Mark I. Langdorf, MD, MHPE* * University of California, Irvine, Department of Emergency Medicine, Irvine, CA Eric Wei, MD† † University of Michigan, Ann Arbor, MI Ali Ghobadi, MD* Scott E. Rudkin, MD, MBA* Shahram Lotfipour, MD, MPH* Supervising Section Editor: David E. Slattery, MD Submission history: Submitted July 18, 2009; Revision Received February 21, 2010; Accepted March 24, 2010 Reprints available through open access at http://escholarship.org/uc/uciem_westjem Introduction: Chest pain (CP) patients in the Emergency Department (ED) present a diagnostic dilemma, with a low prevalence of coronary disease but grave consequences with misdiagnosis. A common diagnostic strategy involves ED cardiac monitoring while excluding myocardial necrosis, followed by stress testing. We sought to describe the use of stress echocardiography (echo) at our institution, to identify cardiac pathology compared with stress electrocardiography (ECG) alone. Methods: Retrospective cohort study of 57 urban ED Chest Pain Unit (CPU) patients from 2002- 2005 with stress testing suggesting ischemia. Our main descriptive outcome was proportion and type of discordant findings between stress ECG testing and stress echo.The secondary outcome was whether stress echo results appeared to change management. Results: Thirty-four of 57 patients [59.7%, 95% confidence interval (CI) 46.9-72.4%] had stress echo results discordant with stress ECG results. The most common discordance was an abnormal stress ECG with a normal stress echo (n=17/57, 29.8%, CI 17.9-41.7%), followed by normal stress ECG but with reversible regional wall-motion abnormality on stress echo (n = 10/57, 17.5%, CI 7.7- 27.4%).
    [Show full text]
  • June-July 2000 Part a Bulletin
    In This Issue... Disclosure of Itemized Statement Providers Must Furnish an Itemmized Statement when Requested in Writing by the Beneficiary .................................................................................................... 6 Prospective Payment System The Outpatient Code Editor Software Has Been Modified in Preparation for the Implementation of Outpatient Prospective Payment System ........................... 8 Reclassification of Certain Urban Hospitals Certain Urban Hospitals in the State of Florida May Be Permitted to Be Reclassified as Rural Hospitals................................................................................ 13 ulletin Final Medical Review Policies 33216, 53850, 70541, 82108, 83735, 87621, 93303, 94010, 95004, A0320, J0207, J2430, J2792, J3240, J7190, and J9999 .......................................... 15 B Payment of Skilled Nursing Facility Claims Involving a Terminating Medicare+Choice Plan Payment of Skilled Nursing Facility Care for Beneficiaries Involuntarily Disenrolling from M+C plans Who Have Not Met the 3-Day Stay Requirement ........................................................................................... 67 Features From the Medical Director 3 Administrative 4 lease share the Medicare A roviders PBulletin with appropriate General Information 5 members of your organization. Outpatient Prospective Payment System 7 Routing Suggestions: General Coverage 12 o Medicare Manager Hospital Services 13 o Reimbursement Director Local and Focused Medical Policies 15 o Chief Financial
    [Show full text]
  • Quantitative Electrocardiography for Prediction Of
    QUANTITATIVE ELECTROCARDIOGRAPHY FOR PREDICTION OF POSTOPERATIVE ATRIAL FIBRILLATION AFTER CARDIAC SURGERY by FLORIAN RADER, M.D. Submitted in partial fulfillment of the requirements For the degree of Master of Science Clinical Research Scholars Program CASE WESTERN RESERVE UNIVERSITY January 2010 CASE WESTERN RESERVE UNIVERSITY SCHOOL OF GRADUATE STUDIES We hereby approve the thesis/dissertation of Florian Rader, M.D. candidate for the Master of Science degree*. (signed) Regis E. McFadden (chair of the committee) Eugene H. Blackstone, M.D. Ottorino Costantini, M.D. Neal Dawson, M.D. (date) 10-28-2009 *We also certify that written approval has been obtained for any proprietary material contained therein. 2 Table of Contents List of Tables 4 List of Figures 5 Acknowledgments 6 List of Abbreviations 7 Abstract 9 Text Background and Significance 10 Specific aims 12 Methods 13 Results 21 Discussion 46 Limitations 54 Conclusions 54 References 55 3 List of Tables: Table 1: Patient characteristics 24 Table 2: Clinical predictors of postoperative atrial fibrillation 37 Table 3: ECG predictors of postoperative atrial fibrillation 38 4 List of Figures: Figure 1: Relationship of anatomic and ECG changes with POAF 11 Figure 2: Patient flow chart 22 Figure 3: Occurrence of POAF by days after surgery 33 Figure 4: Occurrence of POAF by surgery type 34 Figure 5: ROC curve of final prediction model 35 Figure 6: Calibration curve of final prediction model 36 Figure 7: Adjusted Co-plots of ECG predictors 39 Figure 8: Unadjusted and adjusted co-plot of P wave amplitude 41 Figure 9: Nomogram of final prediction model 42 Figure 10: Nomogram of prediction model with pre-op variables 43 Figure 11: Calibration curve of model without ECG predictors 45 Figure 12: Left atrial sizes by P wave amplitude in aVR 48 Figure 13: Correlation matrix (P wave amplitude, aVR, and left atrial volume) 49 5 Acknowledgments: I thank Dr.
    [Show full text]
  • NC Medicaid: 1R-4, Electrocardiography
    NC Medicaid Medicaid and Health Choice Electrocardiography, Clinical Coverage Policy No.: 1R-4 Echocardiography, and Amended Date: March 15, 2019 Intravascular Ultrasound To all beneficiaries enrolled in a Prepaid Health Plan (PHP): for questions about benefits and services available on or after November 1, 2019, please contact your PHP. Table of Contents 1.0 Description of the Procedure, Product, or Service ........................................................................... 1 1.1 Electrocardiography ............................................................................................................ 1 1.1.1 Electrocardiogram .................................................................................................. 1 1.1.2 Cardiovascular Stress Test ..................................................................................... 1 1.1.3 Microvolt T-wave Alternans .................................................................................. 1 1.1.4 Holter Monitor ....................................................................................................... 1 1.1.5 Cardiac (Ambulatory) Event Monitors .................................................................. 1 1.2 Echocardiography ............................................................................................................... 2 1.2.1 Transthoracic Echocardiography (TTE) ................................................................ 2 1.2.2 Transesophageal Echocardiography (TEE) ..........................................................
    [Show full text]
  • Chapter 2 the Electrocardiogram
    THE ESC TEXTBOOK OF CARDIOVASCULAR MEDICINE 2nd edition 17 Spodick DH. Differential characteristics of the C h a p t e r 2 The Electrocardiogram electrocardiogram in early repolarization and acute pericarditis. N Engl J Med 1976; 295 : 523–6. Francisco G. Cosío, José Palacios, 18 Watanabe Y. Purkinje repolarization as a possible cause of the Agustín Pastor, and Ambrosio Núñez U wave in the electrocardiogram. Circulation 1975; 51 : 1030–7. 19 Voukydis PC. Effect of intracardiac blood on the electrocardiogram. N Engl J Med 1974; 291 : 612–16. 20 Thomas P, Dejong D. The P wave in the electrocardiogram in the diagnosis of heart disease. Br Heart J 1954; 16 : 241–54. References 21 Kaplan JD, Evans T Jr, Foster E, et al . Evaluation of electrocardiographic criteria for right atrial enlargement by 1 Grant RP. Clinical Electrocardiography: The Spatial Vector quantitative two-dimensional echocardiography. J Am Coll Approach , 1957. New York: McGraw Hill. Cardiol 1994; 23 : 747–52. 2 Sodi D, Bisteni A, Medrano G. Electrocardiografi a y 22 Reeves WC, Hallahan W, Schwitter EJ, et al . Two-dimensional Vectorcardiografi a Deductivas , Vol. I, 1964. México DF: La echocardiographic assessment of ECG criteria for right atrial Prensa Médica Mexicana. enlargement. Circulation 1981; 64 : 387–91. 3 Rosenbaum MB, Elizari MV, Lazzari JO. The Hemiblocks , 1970. 23 Sgarbossa EB, Wagner G. Electrocardiography. In Topol EJ Oldsmar, FL: Tampa Tracings. (ed) Textbook of Cardiovascular Medicine , 2007. Philadelphia, 4 Cranefi eld PF. The Conduction of the Cardiac Impulse , 1975. PA: Lippincott Williams & Wilkins, pp.977–1011. Mount Kisko. NY: Futura. 24 Hazen MS, Marwick TH, Underwood DA.
    [Show full text]
  • The History of Vectorcardiography*
    Medical History, Supplement No. 5, 1985: 103-131 THE HISTORY OF VECTORCARDIOGRAPHY* by GEORGE E. BURCH** Vectorcardiography (VCG) is a part of electrocardiography (ECG). The vectorcardiogram displays the various complexes of the electrocardiogram, i.e. QRS, P and T complexes, in the form of "loops" which are determined from vectors representing successive instantaneous mean electric forces from the heart throughout an entire cardiac cycle. Since the heart is a three-dimensional structure, the electric forces from the heart during each heartbeat are oriented three-dimensionally and, therefore, can be represented by a time sequence ofvectors which display the magnitude and direction of these mean electric forces. Anyone who knows the fundamental and theoretical aspects of electrocardiography and knows clinical cardiology and employs electrocardiographs with high frequency response and good fidelity can visualize the detailed configuration of the vectorcardiogram from the electrocardiogram. The electrocardiogram displays the same information as the vectorcardiogram and even provides other information not readily available from the vectorcardiogram, especially temporal phenomena and disorders in cardiac rhythm. Nevertheless, vectorcardiography has developed as a result of the efforts of many investigators who were interested in the use of vector analysis of the cardiac electric potentials recorded from the surface of the body. Such investigations have contributed a great deal to a better understanding of electrocardiography and aspects of electrophysiology. Since the time sequence, magnitude, and spatial direction of the instantaneous mean vectors are determined by the order of depolarization and repolarization of the atria and ventricles which, in turn, are affected by the clinical state of the myocardium, it was considered that the spatial vectorcardiogram could be useful in learning more about the electrophysiology of the heart in normal and diseased states.
    [Show full text]