Date post: | 16-Jul-2015 |
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Health & Medicine |
Upload: | gopisankar-mg |
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Heart Heart
Positive inotropicPositive inotropicDose dependent increase in force of Dose dependent increase in force of contractioncontractionSystole shortened ,diastole is Systole shortened ,diastole is prolongedprolongedStroke volume maintained upto Stroke volume maintained upto considerabe impedenceconsiderabe impedence
More complete emptying of ventricles—More complete emptying of ventricles—inc cardiac outputinc cardiac output
Tone-no effectTone-no effectRate HR is decreasd—improved Rate HR is decreasd—improved circulation restores the diminished vagal circulation restores the diminished vagal tone and abolishes sympathetic tone and abolishes sympathetic overactivityoveractivityPlus digitalis slows heart by vago mimetic Plus digitalis slows heart by vago mimetic and extra cardiac actionand extra cardiac action
Vagal tone is increased byVagal tone is increased by1.1. Reflexly thru nodose ganglion and Reflexly thru nodose ganglion and
sensitization of baroreceptorssensitization of baroreceptors2.2. Direct stimulation of vagal centrDirect stimulation of vagal centr3.3. Sensitisation of SA node to AchSensitisation of SA node to Ach
ExtravagalExtravagal1.1. A direct dippressent action on SA node A direct dippressent action on SA node
and AV nodeand AV node
Atrium Atrium 1.1. Decreased by vagal actionDecreased by vagal action2.2. Increased by direct acctionIncreased by direct acction
Net effect more by vagus---excitatory Net effect more by vagus---excitatory and inhomogenous and inhomogenous
VentricleVentricle1.1. ERP reducedERP reduced
AV node and B of HisAV node and B of His1.1. increasedincreased
Conduction Conduction
AV conduction slowed-due to AV conduction slowed-due to reduction in rate of 0 phase reduction in rate of 0 phase depolerizationdepolerization
ECG changesECG changes
Decreasd amplitue or iversion of T Decreasd amplitue or iversion of T wavewaveIncreased PR intervelIncreased PR intervelAV block at toxic dosesAV block at toxic dosesShortening of QT intervalShortening of QT intervalDepression of ST segment (Salvador Depression of ST segment (Salvador Dali's mustache )Dali's mustache )
ADRADR
CardiacCardiac1.1. Tachy arryhthmiasTachy arryhthmias
if due to diuretics + digitoxin---if due to diuretics + digitoxin---hypo K---supply Khypo K---supply KK ---decrease binding of glycosides K ---decrease binding of glycosides to Na –K-ATPaseto Na –K-ATPaseAcute—donot give KAcute—donot give K