Objective—To measure cardiac output in healthy
female anesthetized dogs by use of lithium dilution
cardiac output and determine whether changes in
mean arterial pressure were caused by changes in
cardiac output or systemic vascular resistance.
Design—Prospective clinical study.
Animals—20 healthy female dogs.
Procedure—Dogs were anesthetized for ovariohysterectomy.
Ten dogs breathed spontaneously throughout
anesthesia, and 10 dogs received intermittent
positive-pressure ventilation. Cardiovascular and respiratory
measurements, including lithium dilution cardiac
output, were performed during anesthesia and
Results—Mean arterial pressure and systemic vascular
resistance index were low after induction of
anesthesia and just prior to surgery and increased
significantly after surgery began. Cardiac index (cardiac
output indexed to body surface area) did not
change significantly throughout anesthesia and
Conclusions and Clinical Relevance—Results provide
baseline data for cardiac output and cardiac index
measurements during clinical anesthesia and surgery
in dogs. Changes in mean arterial pressure do not
necessarily reflect corresponding changes in cardiac
index. (J Am Vet Med Assoc 2005;227:1419–1423)
Objective—To measure cardiac output and other hemodynamic variables in anesthetized dogs undergoing laparotomy because of abdominal neoplasia.
Design—Prospective case series.
Animals—8 dogs with splenic or hepatic tumors.
Procedures—Dogs were anesthetized and underwent abdominal laparotomy. End-tidal isoflurane concentration, heart rate, arterial blood pressures, cardiac output, arterial pH, blood gas partial pressures, PCV, and plasma total protein concentration were measured at set intervals before, during, and after surgery. Cardiac index, stroke index, and systemic vascular resistance index were calculated.
Results—End-tidal isoflurane concentration was lowest before and after surgery. Heart rate did not change significantly throughout the anesthetic period. Arterial blood pressures and systemic vascular resistance index were highest shortly after surgery began; cardiac index and stroke volume index did not change significantly during surgery but increased significantly after surgery ended.
Conclusions and Clinical Relevance—Results suggested that in dogs undergoing laparotomy because of abdominal neoplasia, changes in arterial blood pressures were not necessarily indicative of qualitatively similar changes in cardiac index.
Case Description—A 5-year-old male German Shepherd Dog was evaluated because of a 5-month history of progressive lethargy, weight loss, and heart failure.
Clinical Findings—On physical examination, bounding femoral pulses and systolic and diastolic murmurs were detected. Echocardiography revealed severe aortic valve insufficiency (AVI) and a large vegetative lesion on the aortic valve consistent with aortic valve endocarditis. The AVI velocity profile half-time was 130 milliseconds; the calculated peak systolic pressure gradient across the aortic valve was 64 mm Hg. Left ventricular diameter during diastole was 63.6 mm (predicted range, 40.2 to 42 mm) and during systole was 42.9 mm (predicted range, 25.4 to 27 mm). Systolic, diastolic, and mean arterial blood pressures were 120, 43, and 65 mm Hg, respectively.
Treatment and Outcome—To palliate severe AVI, the descending aorta was occluded (duration, 16.75 minutes) and heterotopic implantation of a porcine bioprosthetic heart valve in that vessel was performed. After surgery, systolic, diastolic, and mean arterial blood pressures were 115, 30, and 61 mm Hg, respectively, in the forelimb and 110, 62, and 77 mm Hg, respectively, in the hind limb. Within 6 months, the AVI velocity profile half-time had increased to 210 milliseconds, indicating diminished severity of AVI. After 24 months, the dog was able to engage in vigorous exercise; no pulmonary edema had developed since surgery.
Clinical Relevance—Heterotopic bioprosthetic heart valve implantation into the descending aorta during brief aortic occlusion appears feasible in dogs and may provide substantial palliation for dogs with severe AVI.