Heart Failure and Angina Flashcards
What is heart failure?
Condition in which the heart can’t pump enough blood to meet the body’s needs
Sometimes because the heart doesn’t fill with enough blood, sometimes because the heart can’t pump with enough force, sometimes both
What are the two types of heart failures? How often does each occur?
Systolic (50%)
Diastolic (50%)
Systolic Heart failure
Weakened heart muscle can’t squeeze as well
Can’t get blood through the body
Ventricles are enlarged and pump out less than 40-50% of blood (normally pumps 60%)
Diastolic heart failure
Stiff heart muscle can’t relax normally
Stiff ventricles fill with less blood than normal
Ventricles pump out about 60% of the blood, but the amount of blood is lower
What are the classifications of Heart failure?
Class I (mild) Class II (mild) Class III (moderate) Class IV (severe)
Excitation-Contraction coupling
Contraction is the result of Ca influx from depolarization causing the release of more Ca from the SR
Liberated Ca binds to troponin leading to a change in the interaction between actin and tropomyosin, exposing myosin
Myosin pulls on the actin as it hydrolyzes ATP, contracting the muscle
Depolarization of the cardiac myocyte leads to what?
Opening of the voltage-gated Ca++ channels
Ryanodine receptor
This is the receptor on the membrane of the SR, and when Ca binds to it, it releases more Ca into the cell
What factors contribute to how well the heart pumps blood?
1) Sensitivity of contractile proteins to Ca
2) Amount of Ca that is released
3) Amount of Ca stored in the SR
4) Amount of Ca that enters the cell upon depolarization
5) Activity of the Na/Ca exchanger
6) Intracellular Na concentration and activity of the Na/K ATPase
Ionotropic drugs
Alter the force or energy of muscular contractions
There are both positive and negative ionotropic drugs
Negative ionotropes
Weaken the force of muscular contractions
Positive ionotropes
Increase the strength of muscular contractions
Chronotropic drugs
May change the heart rate by affecting the nerves controlling the heart, or by changing the rhythm produced by the SA node
Positive chronotropes
Increase the heart rate
Negative chronotropes
Decrease the heart rate
What are the different types of ionotropes used to treat heart failure?
Cardiac glycosides
B-adrenergic receptor agonists
Bipyridines
Cardiac glycosides
Digoxin is the only one used in the US
Blocks Na/K ATPase pump
-internal Na increases
-slows the Na/Ca exchanger, slowing the removal of Ca
What are the theraputic effects of cardiac glycosides/digoxin?
Increase the contractility
- increase ventricular ejection and decrease end diastolic and systolic cardiac size
- Increase CO and increase renal perfusion
- The above effects lead to a decrease in sympathetic and renal responses
What drugs without positive ionotropic effects can be used to treat heart failure?
B-adrenergic receptor antagonists Diuretics ACE inhibitors and angiotensin receptor antagonists Aldosterone receptor antagonists Direct vasodilators
What are the suggested mechanisms of B-adrenergic antagonists used to treat heart failure?
Attenuation of adverse effects of catacholamines
Up-regulation of B-receptors (possibly through decreased desensitization)
Decreased HR
Decreased catacholamine-mediated remodeling
Most patients (91%) of patients with heart disease also have what?
Periodontitis
Angina
Pain or discomfort in the chest that happens when some part of the heart does not receive enough oxygen from the blood
What are the different types of angina?
Classical/Typical/Stable/Exertional Angina
Prinzmetal/Variant Angina
Unstable Angina
Classical/Typical/Stable/Exertional Angina
Due to fixed and stable plaque
Prinzmetal/Variant Angina
Due to spasm of the coronary artery
Unstable Angina
Due to unstable plaque
What drugs can be used to treat Anginas?
Nitrates/Nitrites B-adrenergic receptor blockers Calcium channel bloackers Aspirin, antiplatelet, and anticoagulant drugs Ranolazine
Nitrates and nitrites used to treat angina are what?
Esters of nitrous or nitric acid
All of the organic nitrates/nitrites used to treat angina are prodrugs that spontaneously produce what?
Nitric oxide - produce vasodilation
Nitroglycerin
Apply under the tongue for acute episodes of angina; can also be absorbed in GI tract or skin
Therapeutic effect is apparent within 1-3 minutes of sublingual tablets, 30-60 minutes of applying ointment or patch, and 1-2 minutes via IV
Longer acting nitrates are effective when?
Effective when taken orally
What are adverse effect(s) of nitroglycerin and other nitrates?
Headache
High doses of organic nitrates can cause what?
Postural hypotension
Facial flushing
Tachycardia
What effect can viagra have when taken with nitrates?
Potentiates the action of nitrates - leading to dangerous hypotension
How do B-blockers help treat angina?
Decrease HR and O2 demand in the SA node
Decrease contractility and O2 demand in the ventricle myocardium
Decrease BP and O2 demand in arterioles
How do Ca-channel blockers help treat angina?
Decrease HR and O2 demand in the SA node
Decrease contractility and O2 demand in the ventricular myocardium
Increase vasodilation and O2 supply in the coronary arteries
Decrease BP and O2 demand in the arterioles
