Flutter atrial e taquicardia ventricular em cão com síndrome dilatação e vólvulo / gástrico / Atrial flutter and ventricular tachycardia in dog with gastric-dilation volvulus Complex

ABSTRACT

Background: Gastric-dilation volvulus complex (GDV) is an acute condition characterized by dilation of the stomach associated with rotation around its mesenteric axis. Cardiac arrhythmias, especially of ventricular origin are frequently found in animals with GDV. Ventricular tachycardia is characterized by three or more ventricular premature complexes in sequence. Atrial flutter is a supraventricular arrhythmia uncommon in dogs, characterized by rapid atrial rate and altered atrial depolarization resulting in bidirectional saw-toothed atrial complexes. The aim of this work is describe the cardiac arrhythmias and electrocardiographic patterns observed in a postoperative period of seven days in a dog with GDV syndrome. Case A 2-year-old female dog of Fila Brasileiro breed was presented to veterinary hospital due to an acute onset of abdominal distension. Clinical findings included hyperemic mucous membranes, capillary refill time of less than two seconds, normal sounds in cardiac auscultation, heart rate of 160 beats per min, tachypnea, normal femoral pulses and an increased abdominal volume compatible with accumulation of gas. The surgical procedure was the treatment of choice for correction of GDV syndrome. The stomach was dilated, rotated 180 degrees clockwise and possibly with a necrotic area. The spleen was congested and infarcted. During surgery, the patient had a period of low oximetry and two isolated ventricular premature complexes, treated with lidocaine in bolus. In the postoperative period, the electrocardiographic monitoring revealed the presence of two types of arrhythmia. Ventricular tachycardia occurred one day after surgery, being treated with lidocaine in bolus and constant rate infusion. On the third day, the dog developed atrial fl utter, treated with digoxin. On the fourth day, cardiac rhythm returned to normal and showed no further changes up to 7 days after surgery, when the dog was discharged. Discussion: The presence of cardiac arrhythmias in the postoperative period is one of the factors that makes the prognosis worse in dogs with GDV. The etiological mechanism of cardiac arrhythmias in this syndrome has not been elucidated. Among the possibilities are myocardial ischemia, release of myocardial depressant factors, release of catecholamines, electrolyte imbalances and acidosis. Ventricular tachycardia is a relatively common arrhythmia in cases of GDV, which can progress to ventricular fibrillation, the leading cause of deaths from cardiac arrhythmia in dogs with the disease. Among supraventricular arrhythmias, atrial premature complexes were reported, however atrial flutter was not described before in this syndrome. Moreover, the dog developed cardiac arrhythmia until about 72 h after surgery, unlike another reports. An electrocardiographic pattern changed was the size of the P wave, suggesting left atrial enlargement, but thoracic radiography showed a normal-sized cardiac silhouette. Moreover, the animal showed T wave amplitude greater than 25% of the R wave amplitude, which may be related to low oximetry observed at the start of surgery, possible electrolyte imbalances or be physiological. The present case reinforces the importance of electrocardiographic monitoring in the postoperative GDV, including a period of up to 72 h after surgery. Moreover, it is concluded that atrial flutter may be another type of arrhythmia caused by secondary changes of GDV syndrome and confirms the effectiveness of antiarrhythmic therapy with lidocaine in cases of ventricular tachycardia.