Regional myocardial function during contiguous ischaemia in an anaesthetized canine model: comparison of six methods of measurement

• Published in: British journal of anaesthesia : BJA 1994-09, Vol.73 (3), p.371-379
• Main Authors: REITAN, J.A., KIEN, N.D., MOORE, P.G., WHITE, D.A.
• Format: Article
• Language: English
• Subjects: Anaesthetics volatile; Anaesthetics volatile, halothane; Anaesthetics volatile, isoflurane; Anesthetics. Neuromuscular blocking agents; Animals; Biological and medical sciences; Disease Models, Animal; Dog; Dogs; Dopamine - blood; Epinephrine - blood; Female; halothane; Halothane - pharmacology; Heart; Heart - drug effects; Heart - physiopathology; Heart Function Tests - methods; Heart, ischaemia; Heart, myocardial function; Hemodynamics - drug effects; ischaemia; isoflurane; Isoflurane - pharmacology; Male; Medical sciences; myocardial function; Myocardial Ischemia - blood; Myocardial Ischemia - physiopathology; Neuropharmacology; Norepinephrine - blood; Pharmacology. Drug treatments
• ISSN: 0007-0912; 1471-6771
• DOI: 10.1093/bja/73.3.371

During acute myocardial ischaemia, the function of the unaffected muscle is the primary determinant of residual cardiac performance. We compared six methods of measuring regional function in the remaining non-ischaemic segment after acute lig-ation of the left anterior descending (LAD) coronary artery in 16 dogs. Preparation included left ventricular micromanometers, regional sonomicrometer transducers to measure segment length and wall thickness, caval occluders and left atrial catheters for injection of radioactive microspheres to measure regional blood flow. Pulmonary artery, central venous and systemic arterial pressures were measured and regional coronary venous blood was collected for direct myocardial oxygen consumption (Vo2 calculations. Under basal high-dose fentanyl-neuromuscular blocker anaesthesia, the LAD was occluded after addition of halothane or isoflurane at 0.5 or 1.5 MAC concentrations. Regional myocardial function of the non-ischaemic segment was assessed by the following computer-derived indices: percent systolic wall thickening (% WT), velocity of shortening (vs), percent systolic shortening (% SS), regional stroke work (RSW), regional preload recruitable stroke work (RPRSW) and regional end-systolic elastance (Ees). No index demonstrated enhanced function in the nonischaemic segment after LAD ligation and all monitors, except Ees, were sensitive to depression of function represented by a decrease in values after administration of halothane and isoflurane (P < 0.05). Ees values increased with the addition of isoflurane and remained constant with halothane. Circulating concentrations of catecholamines were unchanged after ischaemia, while inhalation agents caused a decrease in the concentrations of adrenaline and dopamine (P < 0.05), but not noradrenaline. Overall, %WT, obtained without complex derivations, monitored regional function well, correlated most closely with load-independent RPRSW and portrayed the lack of augmented function in the normal segment. Ees appeared inconsistent, and consequently unreliable, as an index of regional function.