Medical Pharmacology Chapter 43:  Adult Cardiac Procedures

Section Table of Contents

Site Table of Contents

Previous Page Next Page

Critical factors influencing Coronary Blood Flow

Myocardial Oxygen Supply and Blood Oxygen Content





  • "The "P wave presents atrial activation; the P-R interval is the time from onset of atrial activation to onset of ventricular activation. 

  • The QRS complex represents ventricular activation; the QRS duration is the duration of ventricular activation. 

  • The ST-T wave represents ventricular repolarization.  The QT interval is the duration of ventricular activation and recovery. 

  • The U wave probably represents 'afterdepolarizations' of the ventricles"

  • Courtesy of  Frank G.Yanowitz, M.D. and  The Alan E. Lindsey  ECG Learning Center, used with permission.


  • Rationale for monitoring lead choice: 

    1. Lead demonstrating previous changes, e.g. during preoperative stress test

    2. Knowledge of location coronary artery lesion

    3. Posterior wall ischemia best appreciated using:

      • Atrial lead

      • Esophageal lead

    4. Three-lead intraoperative ECG monitor: modified V5 lead:

      • Left arm lead in the V5 position while monitoring lead I

        • Three-lead system modification which retains lead II and makes a modified V5, by placing the left arm electro-over the V5 position. 

        • Modified V5 is monitored by using the lead selector on lead I" RA = right arm; LA = left arm; LL = left leg

        • Reference 4 (Figure 6-19:McGough, EK, in: Manual of Complications During Anesthesia, (Gravenstein, N, ed), J. B. Lippincott Co., Philadelphia, p 221 1991

Transesophageal Echocardiography (TEE)
  • "Transesophageal echocardiography is performed by using a miniature high frequency ultrasound transducer mounted on the tip of a directable gastroscope-like tube about 12 mm in diameter.

  • Using topical mouth anesthesia and a little sedative, most individuals can swallow the probe without difficulty. 

  • Because the transducer lies in the lower esophagus enclose direct fluid contact with the posterior of the heart, the images are superb since there is no interference by lung tissue"

  • Yale center for Advanced Instructional Media, Yale Tech University School of Medicine, Medical Editor: C. Carl Jaffe, MD; Site Producer: Patrick J. Lynch used with permission, copyright 2000,  Yale University School of Medicine



Intraoperative Transesophageal Echocardiography (TEE): Utility and Assessment of Myocardial Ischemia

Source: Practice Guidelines for Perioperative Transesophageal Echocardiography, A Report by the American Society of Anesthesiologists and the Society of Cardiovascular Anesthesiologists Task Force on Transesophageal Echocardiography,Anesthesiology 1996: 84:986-1006

Section Table of Contents

Site Table of Contents

Previous Page

Next Page


This Web-based pharmacology and disease-based integrated teaching site is based on reference materials, that are believed reliable and consistent with standards accepted at the time of development. Possibility of human error and on-going research and development in medical sciences do not allow assurance that the information contained herein is in every respect accurate or complete. Users should confirm the information contained herein with other sources. This site should only be considered as a teaching aid for undergraduate and graduate biomedical education and is intended only as a teaching site. Information contained here should not be used for patient management and should not be used as a substitute for consultation with practicing medical professionals. Users of this website should check the product information sheet included in the package of any drug they plan to administer to be certain that the information contained in this site is accurate and that changes have not been made in the recommended dose or in the contraindications for administration.  Advertisements that appear on this site are not reviewed for content accuracy and it is the responsibility of users of this website to make individual assessments concerning this information.  Medical or other information  thus obtained should not be used as a substitute for consultation with practicing medical or scientific or other professionals.