What happens in the blood vessels when calcium channels are blocked?
Contraction will be prevented and vasodilation will result
What are the three areas in the heart that have calcium channels?
Myocardium, SA node, AV node
Calcium channels at all three sites in the heart are coupled to _____ receptors
Beta1 adrenergic receptors
Calcium flow in the myocardium increases force of contraction. If the calcium channels in the atrial and ventricular muscle are blocked, ______ will diminish.
What is the pacemaker (SA node) activity of the heart regulated by?
When calcium channels are open in the SA node, spontaneous discharge of the SA node increases. What happens when we block the calcium channels?
Pacemaker activity declines resulting in reduced HR
Since impulses from the SA node must pass through the AV node on the way to the ventricles, regulation of AV conduction plays a critical role in ________.
Coordinating contraction of the ventricles with contraction of the atria
What is the excitability of AV nodal cells regulated by?
In the AV node, when calcium channels are open, calcium entry increases and the cells of the AV node discharge more readily. What happens when we block those calcium channels?
Discharge of AV nodal cells is depressed so there is a decrease velocity of conduction through the AV node
What are the two areas where calcium channels are found?
Blood vessels and heart (myocardium, SA node, AV node)
What are the two types of calcium channel blockers?
Dihydropyridines and non-dihydropyridines
What calcium channels receptors do the dihydropyridines block?
Blood vessel ones ONLY
What calcium channel receptors do the non-dihydropyridines block?
BOTH the blood vessel and heart receptors!
What are the 3 drugs of the dihydropyridines?
What are the indications for giving a dihydropyridine medication?
What are the 2 non-dihydropyridines medications?
What are the indications for giving a non-dihydropyridine medication?
What are the adverse effects of ALL calcium channel blockers?
-Dose dependent peripheral edema
If a patient who is on a CCB comes in and complains that his shoes don't fit anymore, what adverse effect is that patient experiencing?
Dose dependent peripheral edema
The dihydropyridines have an adverse effect that the non-dihydropyridines don't have. What is that adverse effect?
Even though other dihydropyridines can cause reflex tachycardia, it usually is only seen with what type of medication, which is ___?
Medications that are IR (immediate release); Nifedipine IR
Is reflex tachycardia potentially dangerous. Why or why not?
Yes, it can lead to an MI
If you are on a CCB that could cause reflex tachycardia, what other drug could you take to suppress the reflex tachycardia?
What are the 4 adverse effects seen with the non-dihydropyridines ONLY?
-Avoid with heart failure or blocks!!!
Constipation is one of the adverse effects of the non-D drugs. Which drug primarily causes constipation?
Why are diltiazem and verapamil (both non-D drugs) dangerous for clients with heart failure, sick sinus syndrome, or third-degree AV blocks?
These drugs have cardiosuppressant effects. Blockade of the calcium channels in the heart can compromise cardiac function
Diltiazem and verapamil can be dangerous for clients with heart failure, sick sinus syndrome, or third-degree AV blocks because blockade of calcium channels in the heart compromises cardiac function. What happens to these patients when there is blockage of calcium to the SA node?
Diltiazem and verapamil can be dangerous for clients with heart failure, sick sinus syndrome, or third-degree AV blocks because blockade of calcium channels in the heart can compromise cardiac function. What happens to these patients when there is blockage to the AV node?
Partial or complete AV block
Diltiazem and verapamil can be dangerous for clients with heart failure, sick sinus syndrome, or third-degree AV block because blockade of calcium channels in the heart can compromise cardiac function. What happens to patients when there is blockage in the myocardium?
If the heart is healthy, the blockage to the SA node, AV node, or myocardium rarely will have clinical significance. But if you have heart failure, sick sinus syndrome, or third-degree AV block, diltiazem and verapamil can seriously excerbate dysfunction. These two drugs should be used with CAUTION in patients with _____. These two drugs MUST NOT BE USED in patients with ________.
Used with caution in patients with cardiac failure
Must not be used in patients with sick sinus syndrome, second-degree or third-degree AV block
SA node is the pacemaker of the heart. It discharges and impulses spread rapidly throughout the ____ along the intermodal pathways. What does this rapid conduction allow?
Atria; allow the atria to contract in unison
AV node: Impulses from the atria must pass through the AV node to reach the ___.
AV node: In the healthy heart, impulses arriving at the AV node are delayed before going on to excite the ventricles. Is this delay normal? Why or why not?
Yes it is normal; it provides time for blood to fill the ventricles before ventricular contractions
What are the function of the fibers of the His-Purkinje System?
Conduct electrical excitation very rapidly through all parts of the ventricles
His-Purkinje System: Impulses leaving the ___ stimulate the His-Purkinje System.
His-Purkinje System: Impulses conducted rapidly down bundle of His enter the right and left bundle branches and distribute to the branches of the Purkinje fibers. These impulses travel quickly so all regions of the ventricles are stimulated almost simultaneously. What does this all produce?
Synchronized ventricular contractions with resultant forceful ejection of blood