College of Agronomical and Veterinary Sciences, São Paulo State University, Campus of Jaboticabal, Brazil
Cardiac catheterization is largely used in Cardiology whenever non-invasive diagnostic methods, such as echocardiography, are not enough to establish an accurate diagnosis. This technique is also used as part of the therapy procedure for some diseases (i.e., balloon valvuloplasty), as well as in clinical researches of the cardiovascular system.
Due to its invasive nature, cardiac catheterization sometimes requires general anesthesia. Therefore, this report has the goal of describing the anesthetic protocol and the major complications observed during coronary angiocardiography in five dogs (mean weight 11.6 kg; mean age 12) with cardiac disease, which underwent scientific investigation on myocardial perfusion.
The dogs were first given intravenously levomepromazine at 0.5 mg/Kg as premedication. After fifteen minutes, it was administered propofol i.v. until the dog allowed orotracheal intubation. Anesthetic maintenance was done with sevoflurane diluted in oxygen and supplied via a semi-closed circle system. Data was recorded each 10 minutes (M1 to M7), starting 10 minutes after the beginning of sevoflurane vaporization, and the following parameters were analyzed: heart rate (HR), respiratory rate (f), systolic (SAP), mean (MAP), and diastolic (DAP) non-invasive arterial pressure, ETCO2, SpO2, and end-tidal isoflurane concentration. The animal was also maintained under electrocardiographic monitoring at all times.
The following minimum and maximum mean values were determined: HR 98-100 bpm; respiratory rate 12-36; ETCO2 23-38 mmHg; SpO2 98-100 %; SAP 96-115 mmHg; MAP 67-80 mmHg; DAP 53-61 mmHg; end-tidal sevoflurane concentration 2.0-2.5 V%. Data was submitted to ANOVA, but no statistical differences were observed.
Because cardiac catheterization is a minor surgical procedure, anesthesia was maintained in a light plane with 1.0 MAC. However, it is important to emphasize that when the JR catheter was inserted into the right coronary artery, it was observed the occurrence of spiked T waves and severe ST segment depression, which are suggestive of myocardial hypoxia. At this time, dogs were hyperventilated in order to minimize such complication. During positioning of the JR catheter, it was also seen ventricular premature contractions, which were transient most of the times. Nonetheless, two dogs presented ventricular fibrillation when the JR catheter balloon was inflated inside the coronary lumen. Both dogs were successfully defibrillated (4 J/Kg), following immediate removal of the catheter.
Results suggest that this anesthetic protocol can be safely used for angiocardiography in elderly patients with cardiac disease. However, it is important to be aware of the possible complications, especially related to cardiac hypoxia and arrhythmias.