Chronic Drug Therapy, Previous Surgical or Diagnostic Procedures

Anesthesia Pharmacology Chapter 27: Adult Cardiac Procedures in Anesthesia

Chronic Drug Therapy, Previous Surgical, Diagnostic Procedures

Chronic Drug Treatment: major points
- Do not discontinue ß-adrenoceptor perioperatively because discontinuation may cause:
  - Worsening angina (including infarction)
  - Hypertension
- ß-adrenoceptor blocking drugs may be useful during anesthesia because these agents :
  1. Reduce the likelihood of tachycardia
  2. Have antiarrhythmic properties
  3. Are antihypertensive
  4. May reduce myocardial ischemia
  - Conclusions: ß-adrenoceptor blocking drugs
    - Except for long-acting agents ( e.g., nadolol (Corgard)), patient's usual morning does may be given orally along with preanesthetic medications {IV doses may be administered intraoperatively as needed to control heart rate/angina}
- Calcium channel blockers:
  - Generally chronic administration is continued up to the morning of surgery
- Antihypertensive drugs:
  - Generally these drugs are continued through the night before or the morning of surgery because:
    1. They promote reduced perioperative hemodynamic stress
    2. Of manageable interactions with anesthetic and cardiovascular drugs
    3. Rebound hypertension may occur if antihypertensive drugs are abruptly discontinued (particular noted with clonidine (Catapres))
    4. With angiotensin converting enzyme inhibitors (ACE inhibitors): continue these drugs until surgery and start them again as soon as possible postoperatively
      - Patients on ACE inhibitors probably have an attenuated blood pressure response to catecholamine infusions (increased doses may be required)

Issues concerning continuing drug treatment up until the time of surgery
Drug Category	Advantages	Disadvantages
Calcium Channel Antagonists	Antiarrhythmic properties Antihypertensive properties Useful in management of coronary vasospastic disorder	Attenuated response to inotropic agents and vasopressor drugs May promote atrioventricular (AV) conduction bloc; note that calcium is the primary inward current (depolarizing current) carrying ion at the AV node Peripheral vasodilatation after cardiopulmonary bypass
ß-adrenoceptor blocking drugs	Reduced tachycardia Antiarrhythmic properties Antihypertensive effects	May promote bronchospasm Attenuated inotropic response to intraoperative ß-adrenergic receptor agonists
Antihypertensive agents	Antihypertensive effects	Peripheral vasodilation following cardiopulmonary bypass
Diuretics	Probably none	Hypokalemia Hypovolemia
Digitalis glycosides (digitoxin (Crystodigin); digitoxin (Crystodigin))	Inotropic effect Reduces ventricular responses to rapid atrial rates (vagal-mediated AV nodal effect)	Arrhythmias (proarrhythmic effect) Conduction abnormalities, other toxicities Worsens risks associated with hypokalemia
Antiarrhythmic agents	Arrhythmia suppression	May cause toxicity with changes in electrolyte and pH levels
Insulin	Reduced hyperglycemia/ketoacidosis risk	Hypoglycemia {easily managed)

Primary Reference: Ross, AF, Gomez, MN. and Tinker, JH Anesthesia for Adult Cardiac Procedures in Principles and Practice of Anesthesiology (Longnecker, D.E., Tinker, J.H. Morgan, Jr., G. E., eds) Mosby, St. Louis, Mo., pp. 1659-1698, 1998.
Primary Reference: Shanewise, JS and Hug, Jr., CC, Anesthesia for Adult Cardiac Surgery, in Anesthesia, 5th edition,vol 2, (Miller, R.D, editor; consulting editors, Cucchiara, RF, Miller, Jr.,ED, Reves, JG, Roizen, MF and Savarese, JJ) Churchill Livingston, a Division of Harcourt Brace and Company, Philadelphia, pp. 1753-1799, 2000.
Primary Reference: Wray Roth, DL, Rothstein, P and Thomas, SJ Anesthesia for Cardiac Surgery, in Clinical Anesthesia, third edition (Barash, PG, Cullen, BF, Stoelting, R.K, eds), Lippincott-Raven Publishers, Philadelphia, pp. 835-865, 1997