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61 Cards in this Set

  • Front
  • Back
Positive SA node influence
B-adrenergic
Negative SA node influence
Vagal
His-Perkinje influence
B-adrenergic causes increased automaticity
3 things to slow pace of the heart?
1. MDP more negative
2. Phase 4 depol. slower
3. Threshold more positive
EAD
Early After Depolarization
-spon. depol. during phase 3
(muscle stretching, hypoxia)
DAD
Delayed After Depolarization
-spon. depol. during phase 4
(B-adr, card. gly., extracellular ca)
1st degree AV block
long PR interval, benign
2nd degree AV block
occasional missed beat
Mobitz I AV block
heart misses QRS-ventricular beat
Mobitz II AV block
QRS missed-at bundle of His
3rd degree AV block
atrial beats do not go through AV node, waves independent of each other
Atrial flutter
250-350 bpm, very rapid
**TX=propranolol, verapamil
Atrial fibrillation
fibers stim too rapidly--no contraction
**TX=propranolol, anticoagulant
Supraventricular arrhythmia
rapid premature contractions
TX: propranolol, verapamil
ACUTE TX: adenosine
Ventricular tachycardia
180 bpm, dangerous, may lead to ventricular fib.
TX: lidocaine
Ventricular fibrillation
no effective pumping, extremely dangerous, requires defibrillation
TX: epinephrine
Automaticity
cells spontaneously reach threshold and fire action potentials (SA node=normal)
Excitability
tendency to fire at a given stimulus
Autonomic effects
w/ drugs: change heart rate, stroke volume and total peripheral resistance
Treatment goals of anti-arrhythmia drugs (1)
1. Suppress abnormal automaticity (reduce ectopic pacemaking)
Treatment goals of anti-arrhythmia drugs (2)
2. Correct abnormal impulse conduction (prevent reentry of impulses)
Type I drugs
Block sodium channels
Type II drugs
Block sympathetic effects
(Beta blockers)
Type III drugs
Prolong refractory period
(Potassium channel blockers)
Type IV drugs
Block calcium channels
Sodium channel blocker actions
1. reduce automaticity
2. reduce excitability
3. reduce reentry
Beta blocker actions
1. reduce automaticity
2. reduce excitability
3. reduce contractility
4. reduce reentry
IA Key
inhibit sodium channels in active or damaged tissue
IB Key
have greater effects on damaged myocardium
IC Key
very slow off rates
II Key
block sympathetic effects through inhibition of b-ad receptors
***dizziness, ED
Potassium channel blockers
1. increases refractory period
2. little or no effect on automaticity or excitability
III Key
prevent repolarization of channels
***can induce arrhythmias
Calcium channel blockers
1. reduce automaticity
2. minimal effects on excitability
IV Key
targets SA and AV nodal pacemaking cells
***reflex tachycardia
Adenosine treatment
PSVT, WPW syndrome
*causes no beat for a few seconds
CAST trial
BAD: encainide, flecainide, moricizine
GOOD: beta blockers
CHF
^ heart rate & O2 consumption
\/ stroke volume
heart swells, fluid accumulation
Digoxin MOA
^ intracellular Ca and contraction
**low K, high dig binding
TARGET=sod/pot pump
Control HR-sympathetic
cardiac B1-increases cAMP
Control HR-parasympathetic
cardiac M2-decreases cAMP
RX for CHF
inotropic agents w/ vasodilator w/ diuretic
Angina
chest pain caused by coronary blood flow that is inadequate to meet the O2 demands of the myocardium
Angina RX goals
improve heart blood flow and reduce myocardial O2 requirement
RX classes for angina
K channel openers
nitrates
ca channel blockers
ACE inhibitors
beta blockers
potassium channel openers
diminished contraction, vasodilate
Nitric oxide
crucial mediator of VSMC tone
nitrates
(generation of cGMP) relax arterial and venous smooth muscle
**can develop tolerance
calcium channel blockers-angina
vasodilate-reduce afterload
**SE's: hypotension
ACE-I
lower blood pressure
**SE's: cough (bradykinins in lungs), hypotension
ang II receptor blockers
lowers blood pressure
** hypotension but no cough
beta blockers-angina
takes work off heart by b1 and ang-ren system, decreases O2 req of heart
***do not use in diabetes, COPD
Hypertension def
DBP is above 90 mmHg
primary (essential) hypertension
95% of cases
**worsened by obesity, smoking, and not enough exercise
secondary htn
5% of cases
**OCP's, pregnancy, renal disease
complications of htn
CHF, renal failure, stroke
non-RX TX of htn
lose weight, reduce salt, reduce alcohol, stop smoking, do exercise
1st 3 RX's for HTN
ACE, ARB, aldosterone antagonists
2nd 3 RX's for HTN
diuretics, ganglionic blockers, beta blockers
3rd 4 Rx's for HTN
alpha blockers, vasodilators, alpha 2 agonists in CNS, noradrenergic neuron blockers
ganglionic blockers
blocks autonomic system through nicotinic receptor
**used in emergency