Pulsus paradoxus, defined as systolic pressure fluctuation greater than 10 mmHg during the respiratory cycle, is relatively common heart disease of dogs.
This phenomenon is caused by diseases which cause an abnormally large inspiratory decrease in transmural aortic pressure and beat-to-beat aortic flow due to a reduced output of the left ventricle during inspiration due to cardiogenic or non-cardiogenic (blood volume depletion) causes.
In dogs, this is frequently associated with shock, congestive heart failure, cardiac tamponade, pericardial effusion, right ventricular diastolic collapse and bronchoconstriction associated with upper airway obstruction (e.g. foreign body, asthma).
Physical examination findings may include muffled heart sounds and jugular venous distention.
During inspiration, pulmonary arterial pressure drops and left atrial and aortic pressure rises.
In cases of pericardial effusion, pericardiocentesis is indicated for the emergency treatment of secondary cardiac tamponade. Pericardiectomy may improve survival in some dogs. The prognosis varies greatly, depending on the underlying cause.
In severe cases, vagotomy is effective at curing the condition.
in cases of shock-induced pulsus paradoxus, positive pressure ventilation has been shown to reverse this condition.
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