1)     RECOMMENDATIONS

a)      General Approach

i)        Minimize myocardial depression, myocardial oxygen demand/stress, and myocardial irritation

b)      Pre-anesthetic Medications

i)        Hydromorphone, fentanyl, or oxymorphone with midazolam IM

(1)   Diazepam could be substituted for the midazolam but is less well absorbed when given IM

c)      Induction

i)        Etomidate – may be considered the first choice for inducing cardiac cases

(1)   Certainly for patients with decreased myocardial contractility like dilated cardiomyopathy (DCM)

ii)       Hydromorphone, fentanyl, or oxymorphone & a benzodiazepine IV

(1)   Closely monitor heart rate - consider anticholinergics if bradycardic trend is noted and systolic blood pressure drops below 90 mm Hg

iii)     Ketamine with diazepam or midazolam IV

(1)   Reasonable choice if sympathetic release is not considered an inappropriate stress

(a)    Increased heart rate will increase myocardial oxygen demand

(b)   Avoid using if hypertrophic cardiomyopathy (HCM) patient

(2)   Ketamine and midazolam are absorbed efficiently when given IM

(a)    This is an advantage when trying to gain control of a fractious cat with cardiac disease

(i)      Combine with butorphanol to increase the sedative effect

iv)     Propofol

(1)   May be a consideration for some cardiac patients

(a)    More useful for HCM

(b)   Avoid use if DCM or other patients with decreased myocardial contractility

(2)   Precede with 0.2 to 0.4 mg/kg diazepam IV and consider 2 mg/kg lidocaine IV after initial propofol administration to reduce total propofol need

d)      Maintenance

i)        Isoflurane or Sevoflurane

(1)   Generally preferred over halothane as they are generally less arrhythmogenic

(a)    If a significant arrhythmia develops while on Isoflurane or Sevoflurane, however, a switch to halothane may resolve or reduce the severity of the arrhythmia

2)     PRECAUTIONS

a)      Pre-anesthetic Medications

i)        Pre-oxygenate if not overly stressful

ii)       Anticholinergics

(1)   Routine use is not recommended

(a)    Tachyarrhythmias can increase myocardial oxygen demand creating deleterious effects

b)      Induction

i)        Avoid Thiopental

(1)   More myocardial irritation than other choices

(2)   May cause a bigeminy that many consider a benign effect

c)      Maintenance

i)        Halothane

(1)   May be more arrhythmogenic than isoflurane or sevoflurane

d)      Support

i)        Fluids

(1)   You may need to run lower than standard fluid rates

(a)    Overly aggressive IV fluids can create volume overload and pulmonary edema