Skip to Main Content


  • The transesophageal echocardiography (TEE) machine records the electrocardiogram (ECG) simultaneously with all TEE imagery. This is done so that echocardiographers can correlate echo images throughout systole and diastole. Alterations in rhythm can have sweeping and at times ultimately fatal hemodynamic consequences. Thus, the rapid interpretation of abnormal rhythms and their correction is critical in cardiac anesthesia practice.


The ECG remains one of the main monitors used by anesthesiologists. It is primarily employed in anesthesia practice to detect heart rate and rhythm changes, and perioperative myocardial ischemia. The ECG detects electrical currents flowing through the body generated by the electrical activity of the heart. ECG leads are positioned throughout the body and provide various perspectives (depending upon where the lead is placed) of the electrical activity of the heart. Examining the ECG in multiple leads provides the anesthesiologist the ability to discern if perceived changes in ECG pattern are widespread (found in multiple leads) or are perhaps less significant (motion artifact). At the end of diastole, the atria contract providing the atrial contribution to the patient's cardiac output generating the "P" wave. Following atrial contraction, the ventricle is loaded awaiting systole. Systole commences at the QRS beginning with isovolumetric contraction following a 120 to 200 milliseconds conduction delay at the AV node. Subsequently, intracavitary pressure builds, the atrioventricular valves (eg, mitral or tricuspid) close, and the arterioventricular valves (eg, aortic, pulmonic) open resulting in ventricular ejection of the stroke volume (SV). The QRS represents the electrical activity generated by the depolarization of the left and the right ventricles. Depolarization proceeds from the AV node through the interventricular septum via the His-Purkinje fibers. The QRS segment lasts approximately 120 milliseconds. Repolarization of the ventricles produces the ST segment and the T wave. Electrolyte abnormalities (eg, hypocalcemia) and drug effects (eg, droperidol) can delay repolarization leading to a prolonged QT interval. This can result in potentially life-threatening ventricular arrhythmias.


Electrolyte disorders, heart structure abnormalities, and myocardial ischemia can cause aberrations in the patient's baseline ECG without producing an arrhythmia per se (Figure 3–1). Electrolyte abnormalities occur with some frequency perioperatively. Hyperkalemia can present following cardioplegia administration during cardiopulmonary bypass (CPB), following iatrogenic administration, or associated with metabolic acidosis. As the potassium concentration increases, the T wave becomes progressively peaked. Hyperkalemia can ultimately produce broad, complex ventricular activity and asystole. Treatment is with immediate administration of calcium chloride. Glucose and regular insulin are given to lower the potassium concentration.

Figure 3–1A.
Graphic Jump Location

Common ECG findings during cardiac surgery

Figure 3–1B.
Graphic Jump Location

AV sequential and atrial pacing are frequently employed during cardiac surgery as various degrees of heart block are often encountered perioperatively. Prolongation of the PR interval is seen in first-degree heart block here associated with the prolonged QRS complexes often seen during ...

Want remote access to your institution's subscription?

Sign in to your MyAccess profile while you are actively authenticated on this site via your institution (you will be able to verify this by looking at the top right corner of the screen - if you see your institution's name, you are authenticated). Once logged in to your MyAccess profile, you will be able to access your institution's subscription for 90 days from any location. You must be logged in while authenticated at least once every 90 days to maintain this remote access.


Create a Free MyAccess Profile

* Required Fields

Note: If you have registered for a MyAccess profile on any of the Access sites, you can use the same MyAccess login credentials across all sites.

Passwords must be between 6 and 40 characters long (no whitespace), cannot contain characters #, &, and must contain:
  • at least one lowercase letter
  • at least one uppercase letter
  • at least one digit

Benefits of a MyAccess Profile:

  • Remote access to the site off-campus on any device
  • Notification of new content via custom alerts
  • Bookmark your favorite content such as chapters, figures, tables, videos, cases and more
  • Save and download images to PowerPoint
  • Self-Assessment quizzes saved for quick review
  • Custom Curriculum access for both instructors and learners

Subscription Options

AccessAnesthesiology Full Site: One-Year Subscription

Connect to the full suite of AccessAnesthesiology content and resources including procedural videos, interactive self-assessment, real-life cases, 20+ textbooks, and more

$995 USD
Buy Now

Pay Per View: Timed Access to all of AccessAnesthesiology

24 Hour Subscription $34.95

Buy Now

48 Hour Subscription $54.95

Buy Now

Pop-up div Successfully Displayed

This div only appears when the trigger link is hovered over. Otherwise it is hidden from view.