To the Editor:—

In an excellent review of myocardial protection during anesthesia, Warltier et al.  1mention the possibility of improving oxygen availability to the myocardium by a right shift of the oxyhemoglobin dissociation curve. 2–4The beneficial effects of β-blocking drugs also are reviewed. However, the correlation of the well-known fact that β-blockers shift the curve to the right is omitted. This rightward shift may promote oxygen delivery to the myocardium during ischemia. The clear reduction in perioperative infarction rates after β-blockade rests on this fundamental effect.

Warltier DC, Pagel PS, Kersten JR: Approaches to the prevention of myocardial ischemia. Anesthesiology 2000; 92: 253–9
Korkusho OV, Pisaruk AV, Lasitsa TS: Mechanisms of the effect of propranolol on the oxygen transport function of blood in elderly patients with ischemic heart disease. Kardiologia 1986; 26: 54–8
Giunta R: Effect of propranolol on the oxyhemoglobin dissociation curve. Farmaco Pratico 1983; 38: 456–62
Cross GJ: Effect of propranolol and nitroglycerin on the oxyhemoglobin affinity. Eur J Pharmacol 1976; 36: 267–71