Skip to Main Content


Clinical pharmacology associated with cardiac surgery is an important part of patient management. Patients in the perioperative period receive multiple agents that affect cardiovascular and pulmonary function. This chapter summarizes the pharmacology of the agents commonly used for treating the primary physiologic disturbances associated with cardiac surgery, hemodynamic instability, respiratory insufficiency, and alterations of hemostasis. For cardiovascular drugs, the common theme is that pharmacologic effects are produced by intracellular ion fluxes.


Several basic subcellular/molecular pathways are important in cardiovascular pharmacology, as shown in Fig. 4-1. The action potential in myocardial cells is a reflection of ion fluxes across the cell membrane, especially Na+, K+, and Ca2+.1,2 Numerous drugs used to control heart rate and rhythm act by altering Na+ (eg, lidocaine and procainamide), K+ (eg, amiodarone, ibutilide, and sotalol), or Ca2+ (eg, diltiazem) currents. Calcium also has a dominant effect on the inotropic state.3,4

Figure 4-1
Graphic Jump Location

Cardiac ion fluxes and the action potential. The resting membrane potential is largely a reflection of the intercellular/intracellular potassium gradient. Depolarization of the membrane during phase 4 triggers an initial fast sodium channel with overshoot (phase 0) followed by recovery (phase 1) to a plateau (phase 2) maintained by an inward calcium flux and then repolarization owing to an outward potassium flux (phase 3).


Myocardial contractility is a manifestation of the interaction of actin and myosin, with conversion of chemical energy from ATP hydrolysis into mechanical energy. The interaction of actin and myosin in myocytes is inhibited by the associated protein tropomyosin. This inhibition is "disinhibited" by intracellular calcium. A similar situation occurs in vascular smooth muscle, where the interaction of actin and myosin (leading to vasoconstriction) is modulated by the protein calmodulin, which requires calcium as a cofactor. Thus intracellular calcium has a "tonic" effect in both the myocardium and vascular smooth muscle.


Numerous drugs used perioperatively alter intracellular calcium.3,4


Catecholamines (eg, norepinephrine, epinephrine, and dobutamine) with beta agonist activity regulate intramyocyte calcium levels via the nucleotide cyclic adenosine monophosphate (cyclic AMP) (Fig. 4-2). Beta agonists bind to receptors on the cell surface that are coupled to the intracellular enzyme adenylate cyclase via the stimulatory transmembrane GTP-binding protein. This leads to increased cyclic AMP synthesis, and cyclic AMP, in turn, acts as a second messenger for a series of intracellular reactions resulting in higher levels of intracellular calcium during systole. Less well known is that drugs with only alpha-adrenergic agonist activity also may increase intracellular Ca2+ levels, although by a different mechanism.5,6 Although under investigation, the probable basis for the inotropic effect of alpha-adrenergic drugs is the stimulation of phospholipase C, which catalyzes hydrolysis of phosphatidyl inositol to diacylglycerol and inositol triphosphate (see Fig. 4-2). Both ...

Want remote access to your institution's subscription?

Sign in to your MyAccess profile while you are actively authenticated on this site via your institution (you will be able to verify this by looking at the top right corner of the screen - if you see your institution's name, you are authenticated). Once logged in to your MyAccess profile, you will be able to access your institution's subscription for 90 days from any location. You must be logged in while authenticated at least once every 90 days to maintain this remote access.


About MyAccess

If your institution subscribes to this resource, and you don't have a MyAccess profile, please contact your library's reference desk for information on how to gain access to this resource from off-campus.

Subscription Options

AccessSurgery Full Site: One-Year Subscription

Connect to the full suite of AccessSurgery content and resources including more than 160 instructional videos, 16,000+ high-quality images, interactive board review, 20+ textbooks, and more.

$995 USD
Buy Now

Pay Per View: Timed Access to all of AccessSurgery

24 Hour Subscription $34.95

Buy Now

48 Hour Subscription $54.95

Buy Now

Pop-up div Successfully Displayed

This div only appears when the trigger link is hovered over. Otherwise it is hidden from view.