Cardiopulmonary bypass impairs left ventricular function determined by conductance catheter measurement

Area of Science:

• Cardiology
• Cardiovascular Surgery
• Physiology

Background:

• Postoperative cardiac depression is a known complication following cardiac surgery.
• This dysfunction is often attributed to myocardial ischemia and the systemic effects of cardiopulmonary bypass (CPB).
• The independent contribution of CPB to left ventricular (LV) dysfunction requires further elucidation.

Purpose of the Study:

• To evaluate the isolated effect of CPB on postoperative left ventricular (LV) dysfunction.
• To assess changes in LV performance using pressure-volume relationships before and after CPB.

Main Methods:

• Twenty-two 3-week-old piglets underwent sternotomy and one hour of normothermic CPB.
• A conductance catheter was used to measure LV pressure-volume relationships.
• Measurements included end-systolic pressure-volume relationships (ESPVR), LV end-diastolic pressure (LVEDP), and systemic vascular resistance (SVR) before and after CPB. A control group without CPB was used for comparison.

Main Results:

• The ESPVR slope, an indicator of LV contractility, was significantly lower in the CPB group compared to controls post-procedure (p = 0.008).
• Peak dP/dt (a measure of contractility) decreased significantly, while LVEDP increased significantly in the CPB group (p < 0.0001).
• Systemic vascular resistance (SVR) was also significantly lower in the CPB group post-procedure (p < 0.0001).

Conclusions:

• Cardiopulmonary bypass (CPB) alone, even without ischemic arrest, significantly depresses left ventricular (LV) contractility and elastance.
• The conductance catheter technique in a pig model demonstrates the direct negative impact of CPB on LV function.
• Findings suggest CPB itself is a significant contributor to postoperative cardiac depression.