atrial rhythms Flashcards
what are atrial arrhythmias also referred as?
supra ventricular bc they occur above the ventricles
what does supra ventricular mean?
refers to arrhythmias originating outside the sinus node but above the branching portion of the Bundle of Hist
the electrophysiologic mechanism responsible for atrial arrhythmias are? caused by?
increased automaticity, re-entry, or triggered activity (after depolarizations) caused by myocardial schema, electrolyte imbalances inc sympathetic tone (catecholamines), stretch of the chambers, dig toxicity, and pro-arhythmic effects of anti arrhythmic drugs
when would ventricular depolarization be wide?
if there is an underlying bundle branch block (BBB) or if beats are aberrantly conducted (one of the bundle branches has not depolarized and is unable to conduct normally)
what are the 3 basic mechanisms that cause abnormal electrical impulses ?
enhanced automaticity, re-entry, and triggered activity
what is enhanced automaticity?
abnormal condition in which the firing rate of latent pacemaker cells is increased beyond their inherent rate. when the cell membrane becomes permeable to Na during phase 4 which results in leakage Na into the cell and a sharp rise cells that do not ordinarily possess the property of automaticity can acquire enhanced automaticity under certain conditions and depolarize spont
enhanced automaticity can cause what kinds of beats and rhythms?
atrial, junctional and ventricular ectopic beats and rhythms
what are common causes of enhanced automaticity?
common causes are an increase in symp tone (circulating catecholamines), digitalis toxicity, hypoxia hypercapnia myocardial ischemia or infarction, stretching of the heart, hypokalemia, heating or cooling of the heart and certain drugs
what is re-entry?
is the condition in which the progression of an electrical impulse is delayed or blocked (or both) in one or more sections of the conduction system while the electrical impulse is conducted normally through the rest of the conduction system
what does re-entry result in?
delayed impulse entering cardiac cells which have just been depolarized by the normally conducted impulse and if they are depolarized sufficiently, deploring them prematurely and producing ectopic beats and rhythms
re-entry can result in the abnormal generation of what?
a single or repetitive electrical impulse in the SA node, atria, AV junction,bundle branches and purkinje system. this can produce ectopic beats and rhythms originating in any of these areas
what are the most common causes of re-entry?
ischemia and hyperkalemia
what is triggered activity?
an abnormal condition of the latent pacemaker and non pacemaker cells in which these myocardial cells can depolarize more than once following stimulation by a single electrical impulse
what occurs in triggered activity in re: phases?
the level of phase 4 sponta and rhythmically inc after the first depolarization until it reaches threshold potential causing the ells to depolarize. referred to as after-depolarization and can occur immediately following depose (early after depolarization) or late in phase 4 (delayed after depolarization
what does triggered activity cause?
atrial or ventricular ectopic beats occurring singly, in pairs, or in bursts of three or more beats
what are some common causes of triggered activity?
increase in catecholamines, digitalis toxicity, hypoxia, myocardial schema or injury and stretching or cooling of the heart
what are premature atrial contractions?
extra atrial contractions originating from a focus other than the sinus node that occur before the next expected p wave.
is there a pause in premature atrial contractions?
bc the SA node is interrupted by the premature beat, the timing is re-set resulting in incomplete compensatory pause
what are some causes of premature atrial contractions?
overstretcing of the atria (volume, HF, valvular disease), inc sympathetic tone (pain/stress, hypoxia, schema, drugs), stimulants (caffeine, drugs), electrolyte imbalance, and dig toxicity
is the rhythm regular in premature atrial contractions
no bc incomplete pause
where do you see the p waves in premature atrial contraction?
may be buried in t wave before or just early p wave
what are the hemodynamic effects of premature atrial contractions?
asymptomatic but maybe a warning sig of more serious arrythmias
treatment of premature atrial contractions?
underlying cause
dec IV rate, consider a diuretic
when would a QRS not be produced in premature atrial contractions?
when a PAC fires close to a t wave, it may not be conducted into the still refractory bundle branches
what is atrial tachycardia/supraventricular tachy? (SVT)
occurs when an ectopic focus in the atria takes over the sinus node. atrial rate 150-250/min
is there the same amount of QRS in atrial tachycardia/supraventricular tachy? (SVT)
may be the same rate or the AV node may block (2:1)
is the rhythm regular in atrial tachycardia/supraventricular tachy? (SVT)
yes
causes of atrial tachycardia/supraventricular tachy? (SVT)
overstitching of atria (vol, HF, valve dx, cardiomyopathy), inc symp tone, accessory pathways, stimulants, electrolyte imbalance, dig tox
what are the hemodynamic effects of atrial tachycardia/supraventricular tachy? (SVT)
may be asymptomatic
may be symp when rate inc and no time for ventricles to fill so loss of atrial kick, dec CO, SV, de BP (dizzy, headache, syncope), inc workload of heart, palpitations, anxiety, inc ischemia, inc CP
tx for atrial tachycardia/supraventricular tachy? (SVT)
underlying cause, vagal maneuvers, adenosine, Ca channel blockers, beta blockers, amiodarone, procainamide, cardioversion
what is the normal response of the AV node during atrial tachycardia/supraventricular tachy? (SVT)
block. the faster the rate the more they block
antiarrhymics page
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what is amiodarone?
K blocker (anti arrhythmic)
what is dilitizaem?
ca+ channel blocker (anti-arrtythmic)
what are some properties of antiarrhythmic?
neg chrontropy (dec HR), pos or neg isotropy (contractility), neg romotropy (dec conduction thru AV node), depress automaticity, reduce myocardial oxygen consumption, suppress premature ventricular contractions, suppresses re-entry activity, vagolytic, may elevate threshold for Vfib
what is atrial flutter?
a rapid (240–400) ectopic focus in the atria char by flutter waves of a saw tooth appearance and usually a slower regular ventricular response as the Ave node blocks some of the impulses.
what does the AV node do during atrial flutter?
block the impulses to protect the ventricles from raid rates of 240-400
clues of atrial flutter (ECG)
saw tooth pattern of flutter waves (avg of 300), ventricular rate is often 1/2 of atrial but may vary, typically regular but may be irregular if conduction varies with AV bode
causes of atrial flutter?
overstitching ov atria, inc s sympathetic tone, htn, pul htn, thyrotoxicosis, electrolyte imbalance, dig tox
hemodynamic effects of atrial flutter?
may be asymptomatic, but if symp: loss of atrial kick, dec SV, CO, BP, inc workload inc ischemia
tx of atrial flutter?
underlying cause, vagal maneuvers, amiodarone, ca channel blocker, beta blocker, dig, procainamide, cardioversion, anticoagulant ??
what is atrial fib?
results from multiple chaotic foci in the atria (disorganized atrial activity) with may electrical impulses ‘bombarding’ the av node.
QRS in fib?
can be an irregular response depending on if gets impulse. known as the irregular R to R inteval
ECG clues for afib?
no p waves just wavy and irregular ventricular rhythm
causes of afib?
overstitching of atria, inc sympathetic tone, htn, pulm htn, thyroxtoxocisis, electrolyte imbalance dig tox
hemodynamics of fib?
may be asymptomatic, but if symp: loss of atrial kick, dec SV, CO, BP, inc workload inc ischemia
tx of afib?
underlying cause, vagal maneuvers, amiodarone, ca channel blocker, beta blocker, dig, procainamide, cardioversion, anticoagulant , ablation of Av node of pulmonary veins
