Cardio 2 Flashcards
Cardiovascular infections
Rheumatic fever
Infective endocarditis
Pericarditis
Rheumatic fever
Autoimmune reaction to infection with group A strep
Group A strep URI progresses to ARF and potentially rheumatic heart disease
Kids 5-14
Molecular mimicry-immune response targets both bacteria and human tissue
-can lead to lysis of endothelial cells on heart valve
Heart and ARF
Valvular damage
Mitral valve almost always affected
Joint pain ARF
Knees, ankles, hips, elbows (asymmetric
Factors associated with increase risk of ARF
Multiple previous attacks of ARF
Short intervals between attacks of acute rheumatic fever
Increased risk of exposure to strep infections
-kids and adolescents, parents of young kids, teachers, physicians, nurses, day care workers, military recruits, individuals living in crowded situations
Young
High risk patient having poor adherence to secondary prophylaxis
Empiric treatment ARF
Penicillin G and gentamicin
Treat ARF if penicillin allergy or hypersensitive to beta lactams
Erythromycin, azithromycin, clarithromycin, clindamycin
Concern for recurrent acute rheumatic fever in a patient hypersensitive to beta lactams
Erythromycin, azithromycin, clarithromycin
Clindamycin
Not used for prophylaxis of recurrent acute rheumatic fever due to the chance of clindamycin eliciting the opportunistic infection of the GI tract C diff
How manage joint pain and fever with ARF
NSAIDS like asprin or naproxen
Macrolides
Erythromycin
Azithromycin
Clarithromycin
NSAIDS
Asprin (acetylsalicylic acid)
Naproxen
Aminoglycosides
Gentamicin
Infective endocarditis
Prototypic lesion=vegetation
Oral-viridans strep
Skin-staph
URI-HACEK
Empiric treatment for infective endocarditis
Vancomycin (IV) and ceftriaxone
Penicillin and strep viridans
Great
Ceftriaxone and strep viridans
Highly penicillin susceptible
Mid penicillin allergy
Strep viridans gentamicin and penicillin g
Shorter course, no renal disease
Gentamicin and ceftriaxone strep viridans
Shorter drug course no renal disease
Mid penicillin allergy
Vancomycin strep viridans
Severe penicillin allergy
Penicillin desensitization strep viridans
Severe penicillin allergy
Strep viridans
Highly penicillin G susceptible
-penicillin G or ceftriaxone
No preexisting renal disease, uncomplicated native valve infective endocarditis, shorter drug course
-gentamicin+ penicillin or ceftriaxone
Mid beta lactam sensitivity
-ceftriaxone
Severe beta lactam hypersensitivity (history of anaphylaxis)
-preferred: penicilllin G desensitization
Alternat_vancomycin
Penicillin desensitization
Small dose of drug that is gradually increased until the therapeutic dose is acheived
-1 unit of drug is given IV and the patient observed for 15-30 min
No reaction=dose gradually increased every 15-30 min
-tenfold or doubling
Cove 2 million units reached, the remainer of dose can be given
What kind of reaction is penicillin desensitization
IgE mediated allergic
Drug must be physically present to maintainability desensitization
S aureus methicillin susceptible
Nafcillin
Oxacillin
A aureus MRSA
Daptomycin (Alt)
Vancomycin
S aureus mild penicillin allergy
Cefazolin
S aureus severe penicillin allergy
Daptomycin
Vancomycin
S aureus brain abscess accompanying infective endocarditis
Nafcillin
Daptomycin
Similar spectrum of activity as vancomycin
-gram positive, including MRSA
MOA daptomycin
Not known
Binds to the cell membrane via calcium dependent insertion of its lipid tail leading to depolarization, K efflux, and rapid cell death
Treat S epidermis and other coagulates negative staphylococci
Vancomycin
HACEK treat
Ceftriaxone
Enterococci (E faecalis)
Penicillin G or ampicillin or vancomycin)+gentamicin
Aminoglycosides
Gentamicin
1st class cephalosporins
Cefazolin
Aminopenicillin
Ampicillin
3rd gen cephalosporin
Ceftriaxone
Glycopeptide
Vancomycin
Penicillinase resistant penicillins
Nafcillin
Oxacillin
Pericarditis
Inflammation of the pericardial sac
Treat pericarditis in immunocompetent patients
NSAIDS (asprin or naproxen)+colchicine
-important to order CRP to track treatment
Corticosteroids (prednisone) are used in severe or refractory cases
-risk prolong illness or to increase the chance of relapse
Colchicine pharmacodynamics
Anti-inflammatory action mediated by binding to tubulin
- prevents tubulin polymerization into microtubules
- leads to inhibiton of leukocyte migration and phagocytosis
AE colchicine
Diarrhea and occasional nausea, vomiting and abdominal pain
Hair los, bone marrow depression, peripheral neuritis, myopathy
-more likely seen with IV colchicine versus oral colchicine
A 42 yo has fever and unintentional weight loss. A diagnosis of IE is made and blood cultures are positive for s epidermidis
Ok
A 54 male fever, joint pain, night sweats. Past history of rheumatic fever at the age of 9 and for dental surgery 1 month ago. Symptoms started 2 weeks after dental procedure. PE shows mitral regurgitation. The blood cultures were ordered and an empiric therapy was started
Ok
32 females heroin addict was admitted with 2 day fever, shaking, chills, Rigors, and night sweats. Her vitals 100/60, pulse 120, respiration’s 24 , fever. 3 small vegetations tricuspid valve (echo). Three blood cultures drawn and empiric therapy was initiated
Ok
Fast action potential
Ventricular contractile cardiomyocytes
Atrial cardiomyocytes
Purkinje fibers
Deconvolution of cationic fluxes of the cardiac AP
Slow action potential
SA node
AV node
Pacemaker AP phase 4
Slow spontaneous depolarization
- poorly selective ionic influx (NA K) known as pacemaker current (funny current If)-activated by hyperpolarization
- slow Ca influx (T type (transient) Chanel’s)
Pacemaker AP phase 0
Upstroke of action potential
Ca influx through the relatively slow L type (long acting ) Ca channels
Pacemaker AP phase 3
Repolarization
Inactivation of calcium channels with increased K efflux
Factors that determine the rate of firing or automaticity of pacemaker AP
Rate of spontaneous depolarization in phase 4
-decreased slope-decreased rate (need more time to reach threshold potential)
Threshold potential
-the potential at which action potential is triggered
Resting potential
-if potential is less negative, less time is needed to reach the threshold-firing rate increases
Class 1 antiarrhythmic drugs
Na channel blocking drugs
Antiarrhythmic drugs 1A
Quinidine
Procainamide
Disopyramide
1B drugs
Lidocaine
Mexiletine
1C drugs
Flecainide
Propafenone
Class 2 antiarrhythmic
Beta beta blockers
- esmolol
- propranolol
Class 3 antiarrhythmic
K channel blocking
- amiodarone
- sotalol
- dofetilide
- ibutilide
Class 4 antiarrhythmic
Cardioactive CCB
- verampamil
- dilitazem
Miscellaneous antiarrhythmic
Adenosine
Class 1 function of the sodium channel
When sodium channel is activated, Na current occurs down electric and concentration gradients
Resting state
The channel is closed but ready to generated AP
Activated state
Depolarization to threshold opens m gates greatly increasing Na permeability
Inactivated state
H gates are closed, inward Na flux is inhibited , the channel is not available for reactivation-this state is responsible for the refractory period
State dependent block
Drugs have different affinities toward the ion channel protein while it shutttles through different states of the cycle
-most therapeutically useful drugs block activated or inactivated Na channels, with very little affinity towards channels in a resting state
The role of the ___ form of class 1 drugs in binding to a channel
Cationic
Lidocaine! Bind pka 7.8
Kinetics and dissociation na channel blockers
Determines how quickly drugs dissociate fromt he channel
-fast, intermediate or slow kinetics
Class 1A effects
Block Na channels, slow impulse conduction, reduce automatism of latent (ectopic) pacemakers
State dependent block-preferential bind to open sodium chennsle
-ectopic pacemaker cells with faster rhythms will be preferentially targeted
Dissociated from channel with intermediate kinetics
Block K channels
Prolong action potential duration
Prolong QRS and QT intervals of the ECG
Class 1B
Block Na channels
State dependent block-bind to inactivated Na channels
-preferentially bind to depolarize cells
Dissociate from channel with fast kinetics-no effect on conduction in normal tissue
May shorten AP
More specific action on Na channels-do not block K channels, do not prolong AP or QT duration on ECG
Class 1C
Block Na channels, slow impulse conduction
State dependent block-preferentially bind to open (activated Na channels
Dissociate from channel with slow kinetics
Block certain K channels
Do not prolong AP duration and QT interval duration of the ecg
Prolong QRS interval duration
Class 2 drugs
Beta blockers
Sympathetic effect on SA nodal cells
Role of cAMP
Effect on the funny current-If
Effect on Ca channels-lower the threshold
Increased slope due to effects of If and T type Ca channels
Reduce threshold due to effect on L type ca channels
What drugs class 2
Propranolol
Esmolol
How b blockers work
SA node
Decreased HR
AV node
Decreased AV conductance (increase PR interval)
Decreased slope due to effects on If and T type Ca channels
Increased threshold due to effect on L type Ca channels
Type 3
K channel blockers
Types of K channels
Calcium activated
Inwardly rectifying
Tandem pore domain
Voltage gated
K channel blockers regulation of resting potential
Inward (electric) gradient is in equilibrium with the outward (concentration) gradient in the resting cell
Inwardly rectifying k channels are open int he resting state
No current occurs in these channels in a steady state bc of this equilibrium
If extracellular K concentration changes, membrane potential will have to readjust to reach a new equilibrium
K channel blockers regulation of action potential
Voltage gated K channels contribute to the regulation of AP
Repolarization of cell membrane during AP
Limit the frequency of AP (regulate the duration of refractory period)
Class 3 drugs MOA
Block K channels
Prolong AP duration
Prolong QT interval on ECG
Prolong refractory period
Class 4 drugs
Block both activated and inactivated L type calcium channels
Active in slow response cells
- decrease the slope of phase 0 depolarization
- increase L type Ca channel threshold potential
- prolong refractory period in AV node
Decrease the slope of phase 0, increase the threshold of potential at SA node
Name class 4 drugs
Verampamil, dilitazem
MOA class 4
Slow SA node depolarization, cause bradycardia
Prolong AP and conduction in AV duration and conduction time in AV node
Adenosine
Activates K current and inhibtiors Ca and funny currents, causing marked hyperpolarization and suppression of AP in slow cells
Inhibits AV conduction and increases nodal refractory period
Turns on AC increase cAMO and activated protein kinase to open If and ca into cell
K out
Clinical use adenosine
Conversion to sinus rhythm in paroxysmal SVT
AE adenosine
SOB Bronchoconstriction (both a1 and a2b adenosine receptors cause bronchoconstriction)
Chest burning
AV block
Hypotension
Phase 0 fast action potential in cardiac muscle
Voltage dependent fast Na channels open as a result of depolarization; Na enters the cells down its electrochemical gradient
Phase 1 fast action potential in cardiac muscle
K exits cells down its gradient, while fast Na channels close, resulting in some repolarization
Phase 2 fast action potential inc radial muscle
Plateau phase results from K exiting cells offset by and Ca entering through slow voltage dependent Ca channels
Phase 3 fast action potential in cardiac muscle
Ca channels close and K begins to exit more rapidly resulting in repolarization
Phase 4 fast action potential inc radial muscle
Resting membrane potential is gradually restored by Na/K atpase and Na/Ca exchanger
Deconvolutoin of cationic fluxes of the cardiac action potential
Inward Na
Inward Ca
Outward K
Phase 4
Slow spontaneous depolarization
- poorly selective ionic influx (na K) known as pacemaker current (funny current If)-activated by hyperpolarization
- slow Ca influx (via t type (transient ) channels)
Phase ) upstroke of action potential
Ca influx through the relatively slow L type (long acting) Ca channels
Phase 3 repolarization pacemaker action potential
Inactivation of Ca channels with increased K efflux
Factors tha determine the firing rate of pacemaker AP
Rate of spontaneous depolarization in phase 4
(Slope): decreased slope-decreased rate (need more time to reach threshold potential)
Threshold potential-the potential at which AP is triggered
Resting potential -if potential is less negative, less time is needed to reach the threshold-firing rate increases
Procainamide
Class 1a
What is procainamide used to treat
Sustained ventricular tachycardia, may be used in arrhythmias associated with myocardial
MOA procainamide
Directly depresses the activities of SA and AV nodes
Possesses antimuscarinic activity
Has ganglion blocking properties, reduces peripheral vascular resistance-may cause hypotension
Pharmacokinetics procainamide
Active metabolite N acetylprocainamide has class 3 activity, has longer half life, accumulates in renal dysfunction-measurements of both parent drug and metabolite are necessary in pharmacokinetics studies
AE procainamide
Cardiac
- QT interval prolongation
- induction of torsades de pointes arrhythmias and syncope
- excessive inhibition of conduction
Extracardiac
- lupus erythematosus syndrome with arthritis, pleuritis, pulmonary disease , hepatitis fever
- nausea, diarrhea
- agranulocytosis
Quinidine
Natural alkaloid from cinchona bark
Pharmacodynamics and clinical use
Used occasionally for restoring rhythm in atrial flutter/fibrillation patients with normal (but arrhymic) hearts
Sustained ventricular arrhythmia
In clinical trials patients on quinidine twice as likely have normal sinus rhythm, but the risk of death is increased two to three fold
Affords antimuscarinic effect ont he heart-may enhance AV conductance-consequences for AF treatment
Exhibits beta-blocking activity (effect on PR interval is variable)
May cause hypotension->tachycardia
AE quinidine
Cardiac: QT interval prolongation
- Induction of torsades de pointes arrhymia and syncope
- Excessive slowing of conduction throughout the heart
Extracardiac
- GI side effects (diarrhea, nausea, vomiting)
- HA, dizziness, tinnitus (cinchoism)
- thrombocytopenia, hepatitis, fever
Disopyramide use
Recurrent ventricular arrhythmias
Affords potent antimuscarinic effect on the heart
AE disopyramide
Cardiac-QT interval prolongation, induction of torsades de pointes arrhythmia and syncope, negative inotropy effect-may precipitate heart failure, excessive depression of cardiac conduction
Extracardiac
-atropine like symptoms-urinary retention, dry mouth, blurred vision, constipation, exacerbation of glaucoma
Lidocaine MOA
Blocks inactivated sodium channels
Selectively blocks conduction in depolarized tissue, making damaged tissue electrically silent
AE cardiac lidocaine
Rapid kinetics results in recovery form block between AP, with no effect on cardiac conductivity in normal tissue
Use lidocaine
Mono and polymorphic ventricular tachycardia
-very efficient in arrhythmias associated with acute MI
Pharmacokinetics lidocaine
Extensive first pass metabolism-used only by the intravenous route
AE lidocaine
The least toxic of all class 1 drugs
Cardio-may cause hypotension in patients with heart failure by inhibiting cardiac contractility, proarrhythmic effects are uncommon
Neurological effects: paresthesia, tremor, slurred speech, convulsions
Mexiletine
Orally active drug
Electrophysiological and antiarrhythmic effects are similar to lidocaine
Clinical use mexiletine
Ventricular arrhythmias
To relieve chronic pain, espicially pain due to diabetic neuropathy and nerve injury
AE mexiletine
Tremor, blurred vision, nausea, lethargy
Flecainide
1C
Blocks sodium and potassium channels
Has no antimuscarinic effects
Clinical use flecainide
In patients with normal hearts
Treating supraventricular arrhythmias including AF, paroxysmal SVT (AVNRT, AVRT)
Life threatening ventricular arrhythmias, such as sustained ventricular tachycardia
AE flecainide
May be effective in suppressing premature ventricular arrhythmias when administered to
- patients with preexisting ventricular tachyarrhythmias
- patientswith a previous myocardial infarction
- patients with ventricular ectopic rhythms
Propafenone
Class 1C possesses weak b blocking activity
Use propafenone
Prevent paroxysmal AF and SVT in patients with structural disease
In sustained ventricular arrhythmias
AE propafenone
Exacerbation of ventricular arrhythmias
A metabolic tase
Constipation
Do not combine with the CYP2D6 and CYP3A4 inhibtiors as the risk of proarrhythmia may be increased
Clinical indications for the propranolol use in cardiac arrhythmias (class 2 drugs)
Arrhythmias associated with stress
Re-entrant arrhythmias that involve AV node
- AV nodal recent rant tachycardia (AVNRT)
- AV recent rant tachycardia (AVRT)
A fib and flutter
Arrhythmias associated with MI
-decreased mortality in patients with acute MI
Asmolol
Short acting selective beta 1 blocker
HL esmolol
10 min bc of hydrolysis by blood esterases
How is esmolol given
Uses as continuous iv infusion, with rapid onset and termination of its actions
Clinical use esmolol
Supraventricular arrhythmias
Arrhythmias associated with thyrotoxicosis
Myocardial ischemia or acute myocardial infarction with arrhythmias
As an adjunct drug in general anesthesia to control arrhythmias in perioperative period
AE beta blockers (class 2)
Reduced cardiac output
Bronchoconstriction
Impaired liver glucose mobilization
Produce an unfavorable blood lipoprotein profile (increase VLDL and decrease HDL)
Sedation, depression
Withdrawal syndrome associated with sympathetic hyperresponsiveness
Contraindications beta blockers
Asthma
Peripheral vascular disease
Raynaud syndrome
Type 1 diabetics on insulin
Brady arrhythmias and AV conduction abnormalities
Severe depression of cardiac function
Amiodarone
Class 3 blocks K channels
MOA amiodarone
Prolongs QT interval and APD uniformly over a wide range of heart rates
Blocks inactivated sodium channels
Possesses adrenoleukodystrophy activity
Has calcium channel blocking activities
Causes bradycardia and slows AV conduction
Causes peripheral vasodilation (effect may be related to the action of the vehicle)
Clinical use amiodarone
Treatment of ventricular arrhythmias
A fib
Pharmacokinetics amiodarone
CYP3A4-its half life is affected by drugs that inhibit CYP3A4 (cimetidine), or induce it (rifampin)
Major metabolite is active, with very long elimination half life (weeks-months)
Effects are maintained 1 to 3 months after discontinuation, and metabolites are found in the tissues 1 year after discontinuation
Inhibits many CYP enzymes-may affect the metabolism the metabolism of many other drugs
All medications should be carefully reviewed in patients on amiodarone-dose adjustments may be necessary
AE amiodarone
Cardiac
- AV block and bradycardia
- incidence of torsades de pointes is low as compared to other class 3 drugs
Extracardiac
- fatal pulmonary fibrosis
- hepatitis
- photodermatitis, deposits in the skin, give blue grey skin discoloration in sub exposed areas
- deposits of drug in cornea and other eye tissues, optical neuritis
- blocks the peripheral conversion of thyroxine to tiiodothyronine, also a source of inorganic iodine in the body-may cause hypo or hyperthyroidism
Sotalol
Class 2 (non selective beta blocker) and class 3 agent (prolongs APD)
Clinical use sotalol
Treatment of life threatening ventricular arrhythmias
Maintenance of sinus rhythm in patients with a fib
AE sotalol
Depression of cardiac function
Provokes torsades de pointes
Dofetilide
Class 3
MOA dofetilide
Specifically blocks rapid component of the delayed rectifier potassium current-effect is more pronounced at lower heart rates
Pharmacokinetics dofetilide
Eliminated by kidneys, has very narrow therapeutic window-dose has to be adjusted based on creatinine clearance
Use dofetilide
Convert AF to the sinus rhythm and maintain the sinus rhythm after cardioversion
AE dofetilide
QT interval prolongation and increased risk of ventricular arrhythmias
Ibutilide
Similar to dofetilide, slows cardiac repolarization by blockade of the rapid component of the delayed rectified potassium current
How give ibutilide
IV and rapidly cleared by hepatic metabolism
Use ibutilide
Convert a flutter and a fib to sinus rhythm
AE ibutilide
QT interval prolongation and increased risk of ventricular arrhythmias
Patients require continuous ECG monitoring until QT returns to baseline
Clinical use verampamil, dilitiazem
Prevention of paroxysmal SVT
Rate control in AF and a flutter
AE verampamil, dilitazem
Cardiac
- negative inotropy
- AV block
- SA node arrest
- bradyarrhythmias
- hypotension
Extracardiac
-constipation (verampamil)
Clinical use adenosine
Conversion to sinus rhythm in paroxysmal SVT
AE adenosin
SOB
Bronchoconstriction (both a1 and a2b adenosine receptors cause bronchoconstriction)
Chest burning
AV block
Hypotension
MOA adenosin
Activates K current and inhibits Ca and funny currents, causing marked hyperpolarization and suppression of action potentials in slow cells
Inhibits AV conduction and increases nodal refractory period
Proarrhythmia
Drug induced significant new arrhythmia or worsening of an existing arrhythmia
Torsades de pointes (TdP, twisting the pointe)
Rapid form of polymorphic VT associated with the evidence of prolonged ventricular repolarization (long QT syndrome)
What is long qt and torsades de pointes associated with
Often associated with the impaired function of K channels leading to a prolonged period of repolarization
What exacerbates long qt and torsades de pointes
Factors that prolong action potential duration
- slow heart rates
- electrolyte abnormalities (hypokalemia, hypomagnesemia)
Drugs causing long qt syndrome and torsades de pointes arrhythmias
Antiarrhymic drugs-groups 1A and 3 (amiodarone very rarely induces TdP)
Antipsychotics
Antihistamines
Antibiotics
Antidepressants