Characteristics of ischaemic human myocardium: a transoesophageal echocardiographic and voltammetric microelectrode study

Delayed local myocardial power development (primary asynchrony) has been suggested as a marker of ischaemic ventricular dysfunction in humans. However, to prove this, microcirculatory perfusion, microcirculatory oxygenation, and intrinsic mechanical function of the same asynchronous myocardial segment should be studied simultaneously before and after revascularisation. We performed a prospective intraoperative study of 15 patients (age 67 [SD 5] years) at baseline and 30 min after left anterior descending artery grafting. Local tissue perfusion and oxygenation of the anterior left ventricular wall were quantified with a voltammetric microelectrode technique. Transesophageal M-mode echocardiograms and simultaneous high-fidelity left ventricular pressure were measured. Eight patients showed primary asynchrony and 7 did not. Patients with primary asynchrony had local mechanical depression with lower resting values of myocardial work and peak power which increased with surgery. In this group, resting perfusion consistently increased with surgery (32.1 [13] to 54 [31] ml min(-1) 100 g(-1), P < 0.05). In the remaining patients, local work and power were normal, and resting perfusion was consistently higher (90 [9] Ml min(-1) 100 g(-1), P < 0.05 vs primary asynchrony), and fell with surgery. Local tissue oxygen tension was similar in both groups (38 vs 44 mmHg) and did not change with surgery. In patients with chronic coronary artery disease, microcirculatory perfusion, but not pO2, is reduced in regions showing primary asynchrony and impaired mechanical function. Abnormalities in both mechanical function and perfusion normalise within 30 min of revascularisation. These data provide further evidence that primary asynchrony is not only a marker of chronic ischemic ventricular dysfunction, but is associated with a modified contraction pattern in which normal oxygen tension coexists with reduced perfusion.