Dysrhythmia

definition

abnormality in heart beat rhythm

-aka arrhythmia

tachydysrhythmia

v

bradydysrhythmia

tachy: dysrhythmias characterized by being faster than normal

bardy: dysrhythmias characterized by being SLOWER than normal

ability of cell to reach a state of "self-depolarization

-with out help of electrical or neurological impulse

Electrical properties of heart

SA?

AV?

HPS?

SA node: pacemaker of heart

-lowest threshold for self depolarization 

AV node: transmitts electrical impulse from atria to ventricles (with timed delay)

His-Purkinje System (HPS): transmitts electrical impulses quickly through ventricles

      -allows them to contract at even rate.

ECG components

P wave

ECG components

PR interval

ECG components

QRS complex

ventricular depolarization 

and contraction

ECG components

T wave

ECG components

QT interval

-disturbance in impulse formation

--when SA node is sick pace comes from other locations

-disturbances of conduction

--AV block: doesnt allow impulses to be spread through arti to ventricles for contraction

major dysrhythmias

(2)

supraventricular

-impulse arrises before the ventricles (SA or AV)

ventricular 

-much more dangerous 

Anti Dys Rx

quindine

mechanism of action

-na+ blocker (slows a and v conduction)

-delays repolarization 

-anti cholinergic (inc SA and AV conduction)

--can be blocked by digoxin BB or CCB

supraventricular dys > ventricular

diarrhea-give with food

cinchonism- tinntus,HA,N vertigo

cardiotoxicity 

similar to quinidine

-short half life

-less anticholenergic action

--less inc in SA AV conduction

-more serious ADRS

---lupus, blood dyscarsias and cardiotox

used specifically for ventricular dysrhythmias 

-given iv, huge first pass 

ADR's

cns (dizzy fatigue)

nooot pro dysrhythmic

IV only like lidocaine

-ADRs 

hypotension at high doses

not pro dysrhythmic 

-oral derivative of lidocaine

-only used if other Rxs dont work

mex: n,v,d/c and neurologic (tremor)

tocainide: blood dyscrasias and pulmonary fibrosis

propranolol

non selective B blocker

-used for tachydysrhythmias

used in refractory pts (dont respond to other treatmetn)

-tachycardia 

-LOONG HALF LIFE

(1-4 months)

cardiac: bradycardia, av block, HF prodysrhy

pulmonary fibrosis, hepato tox, hypothyroid

-only supraventricular tachydysrhythmias

-CCB effect 

-ADRs: bradycardia, AV block HF, hypotension ect

diltizem= less s/e

-dec SA automaticity (slow heart) and AV block (prevent vent tachycardia)

-inc HPS automaticity= dysrhythmias