Systolic and diastolic functions of the ischemic canine myocardium during halothane anesthesia
Nakahara, T.; Yamada, Y.; Sangawa, J.; Sakata, S.; Koyama, A.; Saito, T.
Masui. Japanese Journal of Anesthesiology 37(5): 552-560
1988
ISSN/ISBN: 0021-4892 PMID: 3411778 Document Number: 320330
Systolic and diastolic functions as well as lactate extraction ratio in the ischemic myocardium were observed during halothane anesthesia (inspired concentration: 1%) using 11 adult mongrel dogs. Blood flow through the anterior descending branch of the left coronary artery (LAD) was reduced by 20% with a screw flow regulator at the beginning of LAD. Using a pair of ultrasonic crystals, myocardial systolic shortening (%SS (actual):L max S-L min S/L max S, %SS (functional): end diastolic length.sbd.end systolic length/end diastolic length) and abnormal wall motion (early systolic lengthening: ESL, post systolic shortening: PSS) were observed. Relaxation factors (time constant (T), LV dt/dt min) were calculated from the fall of left ventricular isovolumic pressure. Changes in regional wall motion correlated with change in lactate balance (%SS (actual) r = 0.69 P < 0.005, % SS (functional) r = 0.54 P < 0.01, PSS r = -0.50 P < 0.05, ESL r = -0.49 P < 0.05). The relationship between %SS (actual) and lactate balance suggests that %SS (actual) is one of the better indicators of ischeima. Abnormal wall motions correlated well with %SS (functional) (PSS r = -0.90 P < 0.005, ESL r = -0.83 P < 0.005). The interaction of different segments of myocardium may be a main cause of abnormal wall motion. T and LV dp/dt min did not correlate with lactate balance or wall motion. Relaxation factors as the function of whole heart could not be assessed quantitatively during moderate regional ischemia.