cards 2 Flashcards
any tachycardia arising “above” the ventricles
supraventricular tachycardia
atrial tachycardias - a flutter and a fib
sinus tachycardia
*usually paroxysmal supraventricular tachycardia (PSVT)
EKG differences between sinus tach and SVT
SVT usually own’t have a P wave
different pathophys of SVT
Re-entry: re-entry circuit is formed. presents with sudden incrase in HR
automaticity: “ectopic” area of heart generates its own abnormal electrical signal. presents with a gradual increase and decrease in HR
what is the gatekeeper that limits the activity that reaches the ventricles?
AV node
what is the most common cause of regular SVT?
AVNRT
what are the causes of AVNRT?
possible link to caffeine, alc, stress. 75% of cases occur in females
symptoms of AVNRT
palpitations, brief hypotension, chest pain
what is AVNRT?
Atrioventricular nodal reentrant tachycardia (AVNRT) is an arrhythmia that occurs because an extra pathway lies in or near the AV node, which causes the impulses to move in a circle and reenter areas it already passed through.
AVNRT pathophys
a re-entry circuit forms within/around AV node. involves fast and slow pathways
**NOT to be confused with an ACCESSORY PATHWAY - this involves normal conduction pathway thats in the heart
EKG findings in SVT/AVNRT
150-250 bpm
regular
p wave absent or after QRS
Narrow QRS- if not narrow, not SVT. If wide, may be arising from the ventricles –> fatal!
how do you manage AVNRT?
goal is to interrupt the circuit and return to normal HR
vagal maneuvers - ice, vasovagal, carotid massage
medications - adenosine (causes complete blockade of AV node) and verapamil
cardioversion
definitive management : radiofrequency ablation of accessory pathway, pacemaker
what happens to the EKG when you administer adenosine?
may look like asystole!
what is AVRT?
accessory pathway within the myocardium allows direct connection between atrium and ventricle -> allows for pre-exitation (bypasses the AV node, conducts impulses faster than AV node) - why there is usually shortened or absent PR interval
what does AVRT require?
two pathways - normal AV conduction pathway + accessory pathway
what is AVRT seen in?
wolff-parkinson-white syndrome
is more AVRT orhodromic or antidromic?
orthodromic- conduction is bidirectional or retrograde form ventricles to atrium
orthodromic AVRT EKG
150-250 BPM
NARROW QRS
inverted P
management of symptomatic AVRT
1 stable or unstable? if unstable -> cardiovert
with orthodromic conduction: tx similar to SVT
with antridromic (Wide QRS) - procainamide, avoid adenosine, verapmil - can progress into Vtach
definitive tx: RFA, possibly implantable pacemaker
what is the safest, most effective drug to administer for acute tx of a wide QRS complex tachycardia of unknown etiology
procainamide
management of asymptomatic WPW
refer for electrophysiological studies
stratify risks: younger age, male gender, inducible AVRT during EP study, multiple acessory pathways
where is a pacemaker inserted into?
percutaneously through subclavian vein or cephalic vein (left pectoral usually)
differences in pacemakers/chambers
single chamber - 1 lead - sends impulses to one atrium or ventricle
dual chamber - 2 leads- sends impulses to one atrium and one ventricle
biventrical- 3 leads - sends impulses to right atrium and both ventricles
what are indications for pacemakers?
depends on symptoms associated with an arrhythmia and location of conduction abnormality
just sinus brady alone is not reason enough to give a pacemaker. Unless they are symptomatic (dizziness, lightheadedness, syncope, fatigue, poor exercise tolerance)
if there is disease present below AV node ( in His-Purkinje system), is pacemaker generally recommended?
yes - less stable
what is the number one cause/indicator for a pacemaker?
symtomatic sinus bradycardia
indicators for implantable defibrillators
can monitor and deliver shocks to terminate Afib with RVR, V tach, V fib. individuals at high risk for cardiac arrest. history of MI with EF
what is the definition of SCD?
death arising from cardiac etiology that occurs in short period of time (usually within 1 hour of symptom onset) - can be in a person with known or unknown cardiac disease.
usually due to a fatal arrhythmia
is SCD same as MI?
NO- SCD is an electrical problem, MI is more circulation
causes of SCD
fatal arrhythmias
vfib - ventricles quiver rapidly and irregularly – heart pumps little or no blood to body
vtach
asystole
structural heart disease (CHD)
HF, hypertrophy, myocarditis, MVP
1 cause of SCD in pt
hypertrophic cardiomyopathy
risk factors of SCD?
prior MI -especially within th elast 6 months
CAD
EF less than 40%
prior episode of cardiac arrest
**anything that affects the electrical system of the heart or how the myocardium responds to it!
management of SCD?
ACLS guidelines
***defibrillation
epinephrine or vasopression if ventricular arrhythmia
atropine if bradycardia or PEA
difference between CAD and CHD?
CAD - pathological proess involving the coronary arteries (usually caused by atherosclerosis)
CHD: includes the diagnosis of angina, MI, and silent MI
CAD
impaired coronary blood flow which can cause oxygen deprivation and angina- usually caused by atherosclerosis
a fixed lesion obstructing what percent or greater of the lumen is generally required to cause symptomatic ischemia precipitated by exercise?
75% or greater
obstruction of what % of lumen can lead to inadequate coronary blood flow even at rest?
90%
when does MVO2 (myocardial oxygen demand) increase?
directly in proportion to HR
with increased contractility
with increased wall tension (increased preload or afterload)
what increases your risk for CAD/angina?
dyslipidemia (low HDL, high LDL, high triglycerides)
age/gender
family history
cigarette smoking
HTN
DM
where do patients usually feel angina?
retrosternal
radiation to ulnar surface of left arm, right arm, outer surfaces of both arms
epigastric discomfort alone or in associate with chest pressure is not uncommon
this is caused by an imbalance in coronary perfusion (due to chronic stenosing coronary atherosclerosis) relative to myocardial demand. Angina usually occurs with physical activity, emotional excitement, and any other cause of increased cardiac workload. usually relieved by rest or administering nitroglycerin.
stable angina
this is characterized by patients having exertional dyspnea rather than exertional chest pain. Caused by exercise induced Left ventricular dysfunction
angina equivalent syndrome
this is an uncommon form of episodic myocardial ischemia that is caused by coronary artery spasm. Angina unrelated to physical activity, HR, or BP. this responds promptly to vasodilators and CCB.
prinzmental/variant angina
which patients are more likeley to get variant angina?
younger, and don’t exhibit classic cardiovascular risk factors (except for cigarette smoking)
associated with other vasospastic disorders, such as Raynaud’s and migraine headache or its treatment
this is very uncommon, are there are more episodes of silent than painful ischemia in the same pt. difficult to diagnoses, except through holter monitor ad exercise testing.
silent ischemia
this refers to a pattern of increasingly frequent pain, often of prolonged duration, that is precipitated by progressively lower levels of physical activity or that even occurs at rest. Caused by the disruption of an atherosclerotic plaque with superimposed partial (mural) thrombosis and possibly embolization or vasospasm (or both)
unstable or crescendo angina - also referred to as preinfarction angina
what is classic angina associated with?
ST-segment depression during acute event (stress test)
occurs with the usual precipitating factors. classic angina is usually very predictable to patients and they can tell exactly what causes it and what makes it better