[Pulmonary wedge pressure and heart frequency measurements during standardized treadmill exercise for extension of left atrial function diagnosis in warmblood horses].

In 12 healthy warmblood horses (six trained and six untrained) the pulmonary wedge pressure and heart frequency was measured at rest and during a standardised exercise test on a treadmill. The mean pulmonary wedge pressure at rest was 14.53 +/- 2.36 mmHg. There was no significant difference in pulmonary wedge pressure either at rest or during exercise between trained and untrained horses. During walking (1.8 m/s) the mean pulmonary wedge pressure was 19.62 +/- 4.03 mmHg, during trotting (4 und 5 m/s) it was between 22.38 +/- 3.92 mmHg and 25.28 +/- 3.7 mmHg. During canter (6 m/s) and gallop (8 m/s) the mean pulmonary wedge pressure increased to a level of 25.54 +/- 4.3 mmHg and 31.86 +/- 4.29 mmHg. There was a significant increase in pulmonary wedge pressure with each incremental step of the standardised treadmill test. Concerning mean heart frequency a highly significant increase could be observed at the beginning and at the end (treadmill speed of 7 and 8 m/s) of the standardised exercise test. At higher intensity of the exercise test (7 m/s and 8 m/s) untrained horses showed a significantly increased heart rate compared to trained horses. Neither at rest nor during the different exercise levels a significant correlation factor greater 0.5 between heart frequency and pulmonary wedge pressure could be observed. The increase of heart frequency and pulmonary wedge pressure during exercise showed no correlation. Between left atrial size and pulmonary wedge pressure a statistical weak correlation could be observed up to a treadmill velocity of 6 and 7 m/s.