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Critical factors influencing Coronary Blood Flow

Myocardial Oxygen Supply & Blood Oxygen Content

Supply Ischemia


Hemodynamic Goals in Anesthesia



  • "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. &  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 (


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