Part 14 Flashcards
Recall the coronary circulation (right and left) of a right dominant heart (the posterior descending artery comes off the right coronary)
- right coronary artery
- right marginal artery branches off to supply lateral right side of heart,SA node, and AV node
- right coronary becomes posterior descending artery that goes around the back of the heart
- near apex anastamoses with anterior interventricular artery
- left coronary artery
- left anterior descending artery branches off and supplies the interventricular septum and anterior walls of both left and right ventricles
- Left anterior descending artery becomes anterior interventricular artery and anastamoses with posterior interventricular artery
- left coronary becomes circumflex artery and supplies left atrium and posterior wall of left ventricle
- circum
Angina pectoris definition
Chest, jaw, shoulder, back, or arm pain/discomfort sometimes associated with other symptoms such as SOB often due to coronary artery disease ischemia but can be due to ANY imbalance in myocardial o2 supply and demand, many can continue to live with the partial occlusion but coronary artery disease is cause of 1/7 deaths in US
Ischemia vs infarct
Ischemia is lack of adequate oxygen supply causing tissue damage, infarct is when tissue has died permanently
3 factors that determine if myocardial ischemia will occur
- O2 carrying capacity of blood
- coronary artery blood flow
- myocardial workload
Coronary artery blood flow occurs during which phase of the cardiac cycle?
diastole
Postprandial angina
Angina that occurs as a result of blood flow being redirected to digest food causing ischemia to the coronary arteries, probably could be mistaken for GERD huh?
Angina pain origin mech of action
- Ischemia reduces formation of ATP
- causes acidosis
- loss of membrane integrity of myocardial cells
- stimulates chemoreceptors and mechanoreceptors in the cardiac vessel
- release of lactate, seratonin, bradykinin, histamine, and adenosine
- Afferent nerve fibers that travel along pathways from the heart in the upper thoracic and lower cervical spinal cord causes referred discomfort to dermatomes that supply afferent nerves to the same segments of the spinal cord as the heart
Levine sign
Positive when patient places his or her fist on the center of the chest indicative of angina pectoris
Big 5 that must be ruled out when a patient presents with chest pain
- acute coronary syndrome (MI, unstable angina)
- aortic dissection
- PE
- tension pneumothorax
- esophageal rupture
Stable angina
Predictable, usually follows a precipitating event, that is generally the same severity as previous attacks, relieved by rest or by the customary dose of nitroglycerin. Caused by fixed coronary artery obstruction 2ndary to atherosclerosis
Prinzmetals’ variant angina
also known as vasospastic angina, Occurs at rest, typically between midnight and 8am, manifests electrocardiographically as episodic ST segment elevations, caused by coronary artery spasms without superimposed CAD (no plaques found in coronary arteries that elicit the symptoms), patients also more likely to develop ventricular arrhythmias, may be triggered by stress, cold, hyperventilation
Microvascular angina - cardiac syndrome X
Angina symptoms, positive exercise test (ST segment depression), normal coronary angiograms so no coronary spasm, patient does not have any other cardiac or systemic diseases (hyperension, diabetes) known to influence vascular function. Defective endothelium dependent dilation in the coronary microcirculation contributes to the altered regulation of myocardial perfusion and the ischemic manifestations predominantly in women. 2% risk of death or MI at 30 days of follow up
Unstable angina definition
New onset (makes it unstable by definition). Increasing severity, duration, or frequency of chronic angina of another type. Occurs at rest or minimal exertion. Not relieved by typical measures. No release of enzymes and biomarkers of myocardial necrosis.
Acute coronary syndromes
-occurs with ST elevation MI, non ST elevation MI, or unstable angina, require immediate catheterization
NY Heart Association Functional Classification of Angina
Class 1 - usually only with strenuous activity
Class II - slightly more prolonged or slightly more vigorous activity
Class III - angina with usual daily activity
Class IV - Angina at rest
Stable angina treatment (4)
- Risk factor modification
- aspirin
- B blockers
- nitroglycerin
Stable vs unstable angina
Stable angina is predictable and fixed with a known onset and treatment, unstable is new onset and or increasing severity or not responding to treatment
Cardioesophageal reflex
A reduction in coronary blood flow by constriciton via a neural reflex when the esophagus is stimulated by acid reflux (in cases of chronic acid reflux could manifest as angina)
Nicotine drug class and mech of action
- Ganglionic stimulant
- At low doses stimulates nicotine receptors and at high doses inhibits nicotine receptors, easily absorbed and distributed across the body (and across the placenta)
Nicotine effects at low doses (such as smoking) (3)
- cardiovascular stimulation of nicotinic receptors in sympathetic ganglia causes vasoconstriction and elevated BP
- gastrointestinal stimulation of nicotinic receptors in parasympathtic ganglia results in gastric acid secretion and increased tone and motility of GI smooth muscle, can produce vomiting (tolerance develops)
- CNS stimulant, moderate doses can cause tremors, high doses can cause convulsions, activates pleasure system in brain
Blocking Ca2+ channels prevents the inward movement of Ca2+ into the cell, preventing ____ in vascular smooth muscle of ___ and therefore causing ____
contraction, arteries, vasodilation
Ca2+ channel blocker activity on the heart (3)
- decreases contractile effect
- decreases speed of conduction of AP in SA and AV node
- Slow heart rate
Coupling of cardiac ca2+ channels to B1 adrenergic receptors
Refers to how in the heart the Ca2+ channels are linked to B1 adrenergic receptors, when B1 receptors are activated, Ca2+ influx is enhanced and when blocked, influx is suppressed, therefore Ca2+ channel blockers and B blockers have identical effects on heart
3 classifications of ca2+ channel blockers and what can they be used on?
- dihydropyridine (only affect blood vessels)
- phenylakylamine (can be used on blood vessels and heart)
- benzothiazepine (can be used on blood vessels and heart)
Verapamil (calan, covera HS, verelan) drug class and mech of action
- phenylakylamine Ca2+ channel blocker
- directly effects heart and blood vessel causing vasodilation, reducing heart rate, AV conduction, and force of contraction, balanced by indirect (reflex) effects of baroreceptors, ultimately resulting in net effect of vasodilation and reduced arterial pressure and increased coronary perfusion
Verapamil (calan, covera HS, verelan) therapeutic uses (3)
- angina pectoris (both vasospastic and effort induced)
- essential hypertension (1st line treatment)
- cardiac arrhythmias
Verapamil (calan, covera HS, verelan) ADR’s (4)
- constipation frequently due to Ca2+ blockade in small intestine
- edema in ankles and feet
- in cardiac diseased hearts could see bradycardia or AV block (in healthy heart effects are minimal)
- should not be used in patients with sick sinus syndrome or 2nd/3rd degree AV block
Verapamil (calan, covera HS, verelan) toxicity reversal (2)
- atropine
- glucagon
Diltiazem (cardizem, dilacor, dilitia XT, tiazac) drug class and therapeutic uses (3)
-Benzothiazepine Ca2+ channel blocker
- angina pectoris
- essential HTN
- cardiac arrhythmias
Diltiazem (cardizem, dilacor, dilitia XT, tiazac) ADR’s (3)
- dizziness
- edema of ankles and feet
- exacerbate bradycardia, AV block, CHF
Nifedipine (adalat, nifedical, procardia) drug class and mech of action
- Dihydropyridines Ca2+ channel blocker
- blocks Ca2+ channels in VSM promoting vasodilation, produces very little blockade of Ca2+ channels in the heart, cannot treat cardiac arrhythmias, increases coronary artery perfusion, but does not affect AV conduction, contractile force, or automaticity reduction, net effect lowers BP, increases HR, increases contractile force
Nifedipine (adalat, nifedical, procardia) therapeutic uses (2)
- angina pectoris (vasospactic and exercise induced) alongside B blocker often to prevent reflex tachycardia
- essential hypertension
Nimodipine (nymalize, nimotop) function
Another type of dihydropyridine that is only capable of producing the Ca2+ blockade in cerebral vessels only approved for prophylaxis of neurologic injury following rupture of intracranial aneurysm
amlodipine vs nifidepine
amlodipine is longer acting requirng only dosed once per day
Some angiotensin II is produced without requiring ____, therefore drugs that block this enzyme do not completely stop angiotensin II production
ACE
ACE inhibitors mech of action and ADR’s (5)
Prevents conversion from angiotensin I to II, major response is vasodilation, reduced aldosterone promoting renal retention of K+ and excretion of Na+ and H2O
- hypotension
- cough due to increased bradykinin levels
- hyperkalemia
- fetal injury use during 2nd or 3rd trimester
- neutropenia
ACE is also known as…
….Kinase II when it functions on bradykinin metabolism
ACE inhibitors therapuetic uses (4) and administration
- hypertension and reduce risk of cardiovascular mortality caused by HTN
- heart failure
- ASAP therapy after MI
- slow progression of established nephropathy (diabetic and nondiabetic)
Oral administration
ACEI advantages to other antihypertensive agents (4)
- no cardiovascular reflexes
- used safely with bronchial asthma
- does not promote hypokalemia or hyperglycemia like seen with thiazide diuretics
- does not induce lethargy, weakness, or sexual dysnfunciton
Angiotensin II action in the vasculature and at the kidney
-constricts afferent arterioles and constricts efferent glomerular arteriole raising glomerular pressure and stasis in high enough conc.
ACEI drug interactions (2)
- hypotensive agents are additive effects
- hyperkalemia if administered with K+ supplements or K+ sparing diuretics
ARB’s therapeutic uses (4) and mech of action
- hypertension
- diabetic neuropathy
- MI
- prevention of MI, stroke, and death in patients with high CV risk
-block binding of angiotensin II to type 1 angiotensin II receptors in blood vessels and other tissues causing dilation of arterioles and veins, block all angiotensin II regardless of where it is produced, decrease release of aldosterone from adrenals, does not impact bradykinin
ARB vs ACEI
ARBs have lower risk of cough/hyperkalemia than ACEI
ARB’s ADR’s (4)
- low incidence of dizziness
- rare angioedema (discontinue if occurs)
- hyperkalemia may occur
- fetal harm in 2nd 3rd trimesters
Aliskiren (tekturna) drug class and mech of action
- Direct renin inhibitor
- binds renin blocking cleavage of angiotensinogen to angiotensin I leading to decreased levels of II and aldosterone
Spironolactone (aldactone) function
Block action of aldosterone at distal tubule causing retention of K+ and increased excretion of Na+ over 48 hr period, has diuretic effects that can treat hypertension or edema (often alongside thiazide or loop diuretic as its weak), can act like progesterone and other steroids and cause gynecomastia or hirsutism (or hyperkalemia obvi!!)
Eplerenone (Inspra)) function
Produces blockade of aldosterone receptors with no effect on receptors for other steroid hormones, weak K+ sparing diuretic used to treat HTN with other agents, only ADR is hyperkalemia
White coat hypertension
Patient’s tendency to have higher blood pressure in presence of doctor’s office due to nerves, still needs to be treated as hypertension but can be mitigated by having patient rest 5 min prior to taking BP
Physical exam for hypertension
- 2 or more bp measurements separated by 2 min sitting, with arm supported at heart level
- verification in contralateral arm
- ocular fundus exam
- exam neck for carotid bruits, jvd, enlarged thyroid
- cardiac murmur, s3, s4, PMI, lifts or heaves
- abdominal bruits
- do CNS exam checking orientation, mental status, cranial nerve, motor and sensory
- do skin exam looking for hydration, pallor, hair loss, edema