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Influence of anesthesia with isoflurane on myocardial velocities of racing pigeons (Columba livia f. domestica).

OBJECTIVE
Tissue Doppler imaging (TDI) is a new technique to measure the myocardial velocities of the avian heart. Using this technique, the present study investigated the influence of isoflurane anesthesia on the systolic and diastolic longitudinal myocardial velocities in racing pigeons.


MATERIAL AND METHODS
Racing pigeons (n = 40) were anesthetized with isoflurane with a semi-open anesthesia system with an anesthetic mask and spontaneous breath. The echocardiographic examination was performed during the stage of surgical anesthesia with the failure of the toe pinch and wing twitch reflexes and with deep regular breaths. Echocardiographic measurements were taken in conscious and anesthetized pigeons in the right parasternal longitudinal horizontal heart view.


RESULTS
The results demonstrated a significant decrease in heart rate, systolic and diastolic A' wave myocardial velocities. The diastolic E' wave velocities were less influenced by anesthesia and significantly decreased only for some heart wall segments. The systolic myocardial velocities were significantly negatively correlated with the heart rate. Using the TDI curve, the isovolumic contraction (IVC) and relaxation time (IVR) and the time of atrioventricular delay during anesthesia could be determined. There is a significant increase in IVR and atrioventricular delay during anesthesia CONCLUSION AND CLINICAL RELEVANCEN: A higher heart rate in anesthesia should be interpreted as a compensation for reduced heart performance. The results of the present study indicate the necessity for establishing normal heart values in conscious and anesthetized pigeons.