Chapter 32
Anesthetic Considerations for Cardiovascular Disease
Does this make your heart skip a beat?
Andre C. Shih
College of Veterinary Medicine, University of Florida, USA
- Q. When performing a pre-anesthetic evaluation on a patient suspected of having cardiac disease, are there any special considerations?
- A. As with any patient undergoing general anesthesia, a complete physical exam should be performed in a manner that does not stress the already compromised patient. A complete history with a complete list of currently prescribed drugs is also important. Due to ongoing medications, cardiac disease patients are prone to hypotension, hyponatremia, hypokalemia, and azotemia. The pre-anesthetic work up should include, in addition to the physical exam, a CBC, serum chemistry (specifically a renal panel), non-invasive blood pressure (BP), echocardiogram (Echo), electrocardiogram (ECG), and thoracic radiographs.
Cardiac patients have a lower cardiac vital reserve capacity; human error that leads to anesthetic drug calculation errors, delays in intubation, provision of oxygen, monitoring, and supportive care can be devastating in a patient with cardiac disease. Before the patient is brought to the induction area, ensure that the anesthesia machine and all monitoring equipment are working properly. The number of drugs required during a cardiac procedure can be intimidating; printing a table with the pre-calculated doses of any emergency agents will save time and decrease morbidity. An example of this table can be found in Table 32.1. Additionally, creating a printed table with a checklist (Box 32.1) would ensure that equipment malfunction is detected before the procedure, avoiding unnecessary delays and complications.
Table 32.1 Examples of different drugs and recommended doses to have available when anesthetizing a patient with cardiac disease.
Drugs
Dose
Volume
Route
Vasoactives and Inotropes:
Epinephrine
Dopamine
Dobutamine
Ephedrine
Isoproterenol
0.01–0.1 mg/kg
2–10 ug/kg/min
1–10 ug/kg/min
0.1 mg/kg
0.1–0.3 ug/kg/min
IV
IV infusion
IV infusion
IV
IV slow
Vasodilators:
Nitroprussate
Nitroglycerine
1–2 ug/kg/min
IV infusion
Dermal
Antiarrhythmic:
Lidocaine
Procainamide
Esmolol
Atropine
Glycopyrrolate
Amiodorone
Magnesium sulfate
1–2 mg/kg
0.5 mg/kg
0.5 ug/kg or CRI of 100–200 ug/kg/min
0.04 mg/kg
0.02 mg/kg
5 mg/kg
20 mg/kg
IV
IV
IV
IV
IV
IV slow
IV
Others:
Hypertonic saline
Hetastarch
Furosemide
Nitric oxide
Albuterol spray
1–4 ml/kg
1–10 ml/kg
0.1–2 mg/kg
Inhalant
Inhalant
IV
IV
IV
Inhalant
Inhalant
- Q. Which anesthetic drug is the safest for cardiac patients?
- A. Unfortunately, no anesthetic drug is safest. The complexity of the pathophysiologic changes with cardiac disease and the specific types of cardiac disease make it impossible for one anesthetic drug to be safe for all cardiac patients. For example, patients with mitral regurgitation (MR) may benefit from drugs that increase basal heart rate and cause mild vasodilation. On the other hand, a patient with hypertrophic cardiomyopathy (HCM) would not do well with a drug that causes tachycardia and vasodilation because of the increased myocardial oxygen demand of tachycardia. Most general anesthetic agents (inhalants and induction drugs) depress contractility and cause hypotension. In order to choose a good anesthetic protocol it is important to understand how anesthetic drugs affect the cardiovascular system.
- Inhalant anesthetics (i.e., isoflurane, sevoflurane): The overall effect of inhalant anesthetics is a reduction in blood pressure and cardiac contractility. To alleviate those negative cardiovascular effects, the concomitant use of sedatives/local anesthetics and opioids reduce required concentrations of inhalants (MAC sparing effect). Mask or chamber induction without proper sedation causes extreme stress and should not
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- A. Unfortunately, no anesthetic drug is safest. The complexity of the pathophysiologic changes with cardiac disease and the specific types of cardiac disease make it impossible for one anesthetic drug to be safe for all cardiac patients. For example, patients with mitral regurgitation (MR) may benefit from drugs that increase basal heart rate and cause mild vasodilation. On the other hand, a patient with hypertrophic cardiomyopathy (HCM) would not do well with a drug that causes tachycardia and vasodilation because of the increased myocardial oxygen demand of tachycardia. Most general anesthetic agents (inhalants and induction drugs) depress contractility and cause hypotension. In order to choose a good anesthetic protocol it is important to understand how anesthetic drugs affect the cardiovascular system.
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