Evidence of functional myocardial ischemia associated with myocardial dysfunction in brain-dead pigs.

Abstract

BACKGROUND:

Cardiac dysfunction after brain death has been documented, but its mechanisms remain unclear. Myocardial ischemia has been suggested as a possible cause. The aim of the present study was to investigate the existence of an imbalance between myocardial oxygen delivery and demand as a possible cause of myocardial dysfunction in brain-dead pigs.

METHODS AND RESULTS:

Interstitial myocardial lactate and adenosine concentrations were assessed with cardiac microdialysis in 2 groups of animals: brain-dead pigs (n=7) and brain-dead pigs treated with labetalol (10+/-3 mg/kg) (n=7). Heart rate (HR), left ventricular (LV) dP/dt(max), rate-pressure product (RPP), cardiac output (CO), and left anterior descending coronary artery blood flow (QLAD) were continuously monitored. Brain-dead pigs exhibited a transient significant increase in HR, LV dP/dt(max), RPP, and CO and a limited increase in QLAD. This resulted in functional myocardial ischemia attested to by the significantly increased adenosine and lactate microdialysate concentrations. In brain-dead pigs treated with labetalol, there was a moderate increase in HR, QLAD, and adenosine microdialysate concentrations; LV dP/dt(max), RPP, CO, and myocardial lactate concentrations remained stable, confirming the preservation of aerobic metabolism.

CONCLUSIONS:

Brain death was associated with an increase in myocardial interstitial adenosine and lactate concentrations, as well as with myocardial dysfunction; all were attenuated by labetalol, suggesting an imbalance between oxygen consumption and oxygen delivery as a possible cause of myocardial dysfunction after brain death.

• Authors: C Seguin, Y Devaux, S Grosjean, E M Siaghy, P Mairose, F Zannad, N de Talancé, D Ungureanu-Longrois, P M Mertes
• Journal: Circulation (Circulation) Vol. 104 Issue 12 Suppl 1 Pg. I197-201 (Sep 18 2001) ISSN: 1524-4539 [Electronic] United States
• PMID: 11568055 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Sympatholytics
• Lactic Acid
• Adenosine
• Labetalol
• Oxygen

Topics

• Adenosine (metabolism)
• Animals
• Blood Flow Velocity (drug effects)
• Blood Gas Analysis
• Blood Pressure
• Brain Death (physiopathology)
• Cardiac Output (drug effects)
• Cardiomyopathies (complications, physiopathology)
• Coronary Circulation (drug effects)
• Heart Rate (drug effects)
• Labetalol (pharmacology)
• Lactic Acid (metabolism)
• Microdialysis
• Myocardial Ischemia (complications, diagnosis, physiopathology)
• Myocardium (metabolism)
• Oxygen (metabolism)
• Oxygen Consumption
• Swine
• Sympatholytics (pharmacology)
• Ventricular Function, Left (drug effects)