Inhaled nitric oxide effectively decreases right heart afterload following right heart infarct in pigs.

OBJECTIVE

To test the hypothesis that nitric oxide is beneficial in acute right heart failure after right ventricle infarct. Right ventricle infarct results in a decrease in right heart function with a subsequent reduction in ejection fraction and cardiac index. The pulmonary circulation is compromised as the right ventricle weakens, and the resulting stasis and further weakening of the ventricle present clinically as an increase in right heart afterload. Pulmonary vasodilation should ease these hemodynamic symptoms of right heart infarct.

DESIGN

Ten 3-4-month-old pigs were chosen as experimental animals. All animals were cannulated, a sternotomy was performed and branches of the right main coronary were ligated to cause infarct of the right ventricle. After a 4-h stabilization period, all animals received fluid preload with a dextrose-based solution after which control hemodynamic measurements were recorded. Treatment with inhaled nitric oxide was begun at progressive concentrations and hemodynamic measurements recorded at 30-min intervals.

RESULTS

Nitric oxide treatment significantly reduced right heart afterload, which was also apparent as a reduction in left heart preload. A significant deterioration was observed in cardiac output as well as in left and right ventricle stroke work indices.

CONCLUSION

The use of nitric oxide in this model of right heart infarct in previously healthy young swine effected a decrease in both right heart afterload and left heart preload, with an overall deterioration in global hemodynamics.