EKG (Newman) Flashcards
c
What is the most cause of stroke?
atrial fibrillation
What is the most common cause of suden cardiac death?
ventricular fibrillation
What does the P wave represent?
depolarization of the atria
What does the Q wave represent?
polarization of the septum
What does the RS complex represent
depolarization of ventricles
What does an elevated ST segment indicate
ST elevation MI
What does an DE-elevated ST segment indicate
ischemia
WHat does the T wave represent
repolarization
What causes a positive deflection on an EKG?
vector is parallel to _____
What causes a negative deflection on an EKG?
vector is perpendicular to ______
What causes a straight line on an EKG?
???
At rest, phase 4 is appx ___ mV
With depolarization ____ floods into the cell and the cell becomes _____ mV
At phase 1 ____ ions are moving in and ___ ions are moving out
At phase 2 ____ ions are moving in and ___ ions are moving out
At phase 3, ____ ions are moving in and ___ ions are moving out
-90 mV Na +20 mV Cl- in and K+ out Ca in and K+ out only K+ out
T or F: all heart tissue has the same AP
F
What ion drives an AP conduction in the heart?
Ca influx
During the AP the cell cannot be stimulated to generate another AP during the _____ period
refractory (phase 1-2 is absolute and phse 3 is relative)
What is the threshold potential of automat. cells?
-65 mV
What is the refractory period?
period when the myocyte cannot generate another AP
what are 2 impt concepts for generation of dysrryhtmias?
refractory and threshold
The AV node depolarization is represneted by _____ on the EKG
PR segment
The depolarization of septa is represneted by _____ on the EKG
Q wave
depolarization of ventricles
RS complex
repolarization of ventricles
T wave
increased cardiac muscle mass
hypertrophy
How is hypertrophy Dx?
height of R wave increased
What is the most common cause of LFT ventricular hypertrophy
HTN
**at risk risk for coronary events
What does a wide QRS complex indicate?
delayed activation of ventricles since the tissue is blocked (delay in AP conduction)
What does a prolonged PR segment indicate
heart block due to AV node disease
WHat are the 2 major mech of cardiac arrhythmias?
altered automaticity (alt phase 4) and altered reentry
Why does enhanced automaticity occur?
phase 4 has been altered and risen to threshold potential –> ****a cell fires when it is not supposed to
What causes a cell to inc threshold potential and depolarize inappropritely?
low K+ (inc automaticity) inc symp activity (meds, anxiety) low O2 high CO2 (emphysema) low pH (kidney shut down) fever digitalis (Rx) previous AP***
What is triggered automaticity?
previous AP stimuates an inapproprate firing of AP
What is reentry?
electrical impulse comes down normal pathway but will become blocked at some point and cause a detour of AP along an alternative pathway (circuit loop) and then come back up the original pathway (which is NO LONGER refractory) –> continuous loop of activation –
In order to have cardiac reentry one must have a _______ pathway
continuous (loop)
What are the 3 requirements of reentry
unidirectional block of impulse
continuous loop pathway
alt pathway has slower conduction velocity
WHere is a naturally occurring circuit loop found?
atria???
What is the cause /mechanism of palpitations
block in (atrial?) AV node pathway (natural) that causes arrythmia/reentry
conduction block in the ventricle –>
ventricular tachycardia
dyrrthmias are likely caused by ____
enchanced automaticity or re-entry
no p waves
enhanced automaticity
junctional rhythm
impused started somewhere in AV node
multifocal atrial tachycardia
bunch of atria AP fired inappropriately
person born with alternative pathway that joins atria to ventricles in a rapid pathway (HR of 300 bpm)
wolff-parkinson- white syndrome
with supraventricualr tachycardia
What to anti-arrhythmic agents do?
- reduce automaticity (reduce pahse 4 threshold potential)
- prevent reentry (block alternative pathway that leads to re-entry)
Elevated Ca and decreased K will (increase/decrease) automaticity.
increase
Elevated K and decreased Ca will (increase/decrease) automaticity.
decrease
