This study aims to compare two common ultrasound techniques used during heart surgery: transthoracic echocardiography (TTE) and transesophageal echocardiography (TEE). TTE is performed by placing an ultrasound probe on the chest, while TEE involves inserting a probe into the esophagus, which provides closer and clearer images of the heart. Both methods are part of routine care for patients undergoing heart surgery.

The goal of this study is to assess how well the measurements from TTE and TEE agree in evaluating heart chamber dimensions during surgery and to investigate how factors such as anesthesia, breathing techniques affect these measurements.

This research involves 114 adult patients scheduled for heart surgery at Sunnybrook Health Sciences Centre. Participants will have TTE performed before and after surgery, and TEE will be conducted during surgery. All procedures are part of the usual standard of care.

By comparing these imaging techniques, the study seeks to provide more accurate and up-to-date guidelines for cardiac measurements, ensuring better care for patients during heart surgery.

This observational study compares transthoracic echocardiography (TTE) and transesophageal echocardiography (TEE) in measuring cardiac chamber dimensions in adult patients undergoing cardiac surgery. While both techniques are integral to clinical care, TEE is typically used intraoperatively for its superior image quality, and TTE is performed preoperatively as a non-invasive diagnostic tool. However, differences in measurement values between TTE and TEE, particularly under the physiological changes induced by general anesthesia and positive end-expiratory pressure (PEEP), remain poorly understood. This study seeks to address this gap and update normative cardiac measurement values.

Study Design: A prospective observational study enrolling patients scheduled for coronary revascularization surgery at Sunnybrook Health Sciences Centre (n=114). All imaging procedures are part of routine clinical care.

Primary Objective: To evaluate the agreement between preoperative TTE and intraoperative TEE measurements of cardiac chamber dimensions.

Secondary Objectives:

• To explore how physiological changes from general anesthesia and PEEP impact the correlation between TTE and TEE measurements.
• To analyze how pre-existing cardiac conditions (e.g., hypertension, diabetes, atrial fibrillation) affect the agreement between these modalities.

Inclusion Criteria:

• Age ≥ 18, able to provide informed consent.
• Patients scheduled for coronary revascularization cardiac surgery under general anesthesia.
• With normal left ventricular (LV) systolic function, defined by an ejection fraction of 50% or more, and normal right ventricular (RV) systolic function.
• Requiring intraoperative echocardiographic assessment.

Exclusion Criteria:

• Patients with contraindications to either transthoracic echocardiography (TTE) or transesophageal echocardiography (TEE).
• History of poor-quality echocardiography data that preclude accurate assessment.
• Undergoing emergency cardiac surgery.

Adult patients undergoing elective cardiac surgery, specifically coronary revascularization procedures.

De-identified participant-level data will be made available upon reasonable request to study PI following publication of full trial results.

Data will be available following publication of the full trial results.

Data and supporting information will be made available following reasonable request directly to study PI.