The ventricular filling velocities during diastole and the influence of isoflurane anesthesia on these blood flow velocities of the racing pigeon (n = 43) are evaluated by pulsed-wave (PW) Doppler sonography. Sonographic examination demonstrates an early passive ventricular (E wave) and late active (A wave) ventricular filling. The results indicate differences between the two heart ventricles. Especially, the E wave velocity of the right heart is significantly lower than in the left heart, which is explained by the crescent-shaped cavity of the right ventricle around the left ventricle. The faster active filling velocities are significantly influenced by heart rate in conscious birds. Anesthesia with isoflurane leads to a significant decrease of the diastolic blood flow velocities, and the A wave velocities of both ventricles are especially influenced. Anesthesia with isoflurane induces a high incidence of insufficiencies of the left atrioventricular valve in the preejection period. These observations indicate that a contraction of the left ventricle myocardium is important for a complete valvular closure and for normal functioning of this heart valve. The effective closure of the right atrioventricular muscle valve in anesthetized pigeons supports the observation of the fast innervation of this muscle valve via a direct connection to the right atrium.

Doppler echocardiographic examinations are an important technique for evaluating the blood flow also in avian cardiology. The influence of anesthesia on the blood flow in the heart is in detail unknown for the most avian species. The present study investigated the influence of an isoflurane anesthesia on the systolic blood flow of the aorta and the pulmonary artery in the area of the heart valves examined by pulsed wave Doppler sonography in Racing Pigeons ( Columba livia f. domestica, n = 43). Measurements were taken in conscious and anaesthetized birds in the left (aorta) and right (pulmonary artery) parasternal longitudinal horizontal heart view. The results demonstrated a significant decrease in heart rate and systolic peak flow velocities as well as prolonged ejection times during anesthesia. A positive correlation of systolic peak flow velocity and heart rate could be demonstrated, especially for the pulmonary artery in conscious pigeons. The aortic systolic peak flow velocity and heart rate showed a significantly negative correlation in anaesthetized pigeons. These correlations should be borne in mind in the echocardiographic examination, especially of conscious birds. A higher incidence of second degree atrioventricular block (30.23%) was induced by anesthesia in the Racing Pigeons. These results of the present study indicate the necessity for establishing normal heart values in conscious and anaesthetized individuals.

Tissue Doppler imaging (TDI) is a noninvasive sonographic method of acquiring and quantifying myocardial velocities. This technique is used in human and small animal medicine to diagnose cardiac diseases. Using this technique, we evaluated the longitudinal myocardial peak velocities of the interventricular septum, and the left and right ventricular free walls in the systole and diastole in 40 racing pigeons. The TDI examinations confirmed the movement of the heart base toward the apex in the systole and away from the apex in the diastole. Inhomogeneous distribution of the myocardial velocities with a statistically significant velocity gradient from the basal to the apical myocardial segments was found. The left and right free walls have significantly higher myocardial velocities than the myocardium of the septum. The myocardial velocities during active ventricular filling were significantly higher in the right ventricular free wall than in the left one. The validation of the method resulted in coefficients of variation between 3% and 33% for the systolic and 3% and 75% for the diastolic individual myocardial velocities. Weekly repeated measurements resulted in variation coefficients between 3% and 45% for systolic and diastolic myocardial velocities, respectively.

In avian medicine, Doppler sonographic techniques are used to visualize and estimate blood flow in the heart. In the literature there is a lack of standardized studies of the use of color Doppler flow on healthy avian species. For this purpose, we examined blood flow in the heart in the four-chamber view of clinically healthy awake racing pigeons (n = 43) by color flow Doppler sonography. With this technique the diastolic and systolic blood flow in the heart chambers and the heart valve regions were well visualized. However, the pulse repetition frequency must be adapted to the specific blood flow velocities of the heart region to be measured to reduce aliasing in higher velocities and to visualize blood flow of lower velocities. With the help of color Doppler imaging in the four-chamber view, typical physiological atrial and ventricular blood flow vortex formations were visualized in the avian heart for the first time. In the left ventricle an asymmetric vortex ring in the passive and active ventricular filling, in the right ventricle a great counter-clockwise blood vortex in the active ventricular filling, in the left atrium a vortex clockwise, and in the right atrium counter-clockwise were observed. The knowledge of these physiological blood flow vortices is important to identify pathological blood flow.

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.