Lecture #5 Flashcards
What is the R-R interval?
P-P interval?
Ventricular Rate
Atrial Rate
When might you see variance between atrial and ventricular rate?
AV block
Why does asking rhythm mean?
Are the intervals between the waves the same?
What does PR Interval reflect?
Time of conduction through the AV Node, bundle of His, and bundle branches
What does a PR interval at 0.1 indicate?
Absolutely nothing.
What does a PR interval at 0.25 indicate?
First degree AV block
When might you see a short PR interval?
WPW and LGL syndromes
What does the width of QRS indicate?
What might a broadened ORS indicate?
Time it takes the ventricle to depolarize
WPW Syndrome and Bundle Branch Block
What does the QT interval reflect?
What might a longer QT indicate?
Time it takes the ventricle to repolarize
LQTS
What is indicated by downward Ps or ones without QRS?
2nd/3rd degree AV blocks
What might cause an inverted T wave?
Previous MI
What might cause changes in S-T segment?
Elevated or depressed in MI or ischemia
What might U waves indicate?
What else would you expect?
Hypokalemic Patient
Depressed S-T
Low amp. T waves
Four characteristics of normal sinus rhythm.
QRS after P
PR interval of .12-.2 (3-5 small squares)
RR is regular (0.6-1 second)
Beats all look like eachother
Five types of sinus node dysrhythmias.
Sinus tachycardia Sinus bradycardia Sinus arrhythmia Sinus Arrest Wandering Pacemaker
Four types of atrial dysrhythmia
Premature atrial contraction
Paroxysmal atrial tachycardia
Atrial Flutter
Atrial fibrillation
Four types of ventricular dysrhythmia
Premature ventricular contraction
paroxysmal ventricular tachycardia
torsade de pointes
ventricular fibrillation
Define sinus tachycardia. Causes?
More than 100 beats/minute
Catecholeamines, Sympathetic Stim, Stress, Hypoxia
Define sinus bradycardia. Causes?
Less than 60 bpm (RR over 1 second)
Distance runners, sleep, PS stim,
Define sinus arrythmia. Cause?
Normal variation of sinus rhythm.
Vagal tone effect associated with breathing rates
Mostly in children
Define sinus arrest. Cause?
Failure of pacemaker cells
Define wandering pacemaker. Cause?
Varying rhythm in which P waves may vary in direction, PR interval can vary.
Inflamed/Irritated Atria or Digitalis Toxicity
Define premature atrial contraction (PAC). Cause?
Atrial ectopic focus. Different P wave morphology.
Alcohol, Smoking, Caffeine, Gastric Overload
CHF, Ischemia, COPD
Define paroxysmal atrial tachycardia. Cause?
140-220 bpm.
Ectopic Focus in Atria/AV Node or Re-entry/WPW
Caffeine, Nicotine, Alcohol, Anxiety
Define atrial flutter. Cause?
Atrial Rate = 250-250 bpm
Typically fixed ratio w/ ventricular
Macro-Reentry – movement around openings of VC or Tricuspid
Prevalent in enlarged atria
In atrial flutter, what is seen instead of P wave?
Saw-tooth pattern
What is atrial fibrillation. Cause?
Rapid depolarization (only in A), no discernable P IRREGULARLY IRREGULAR
Inc. Atrial size, decreased conduction velocity, decreased refractory period
– MICROREENTRY LOOPS
What do you see in AV nodal rhythm?
SA has failed. AV takes over.
Inverted P Wave preceding QRS
How to distinguish Atrial Fib and Junctional Rhythm if no Ps around?
Junctional – Regular
Fib – Irregularly Irregular
What are cannon A-Waves
When atria contract during/after onset of ventricular contraction
Caused by RA contracting against closed Tri. Valve
What do you see with idioventricular rhythm?
Wide QRS, Always same shape
20-40 bpm
Define premature ventricular contraction. Cause?
Wide QRS, No P
Ectopic Foci in ventricles
What may premature ventricular contraction lead to?
Ventricular Tachycardia
What is an “R on T” Event. Why do we care?
Premature ventricular contraction during T Wave
Depolarizing pulse may take a cirtuitous route around refractory regions, causing reentry rhythm
Causes Tachycardia or Fibrillation
What is paroxysomal ventricular tachycardia? Cause?
Sudden, Rapid ventricular beat
Often caused by PVC creating reentry
Define torsade de pointes. Cause?
Polymorphic ventricular tachycardia
Hypokalemia and LQTS
Define ventricular fibrillation. Cause?
Ventricles quiver several hundred times/minute
CO drops to zero
“Electrical Storm”
Micro-reentry circuits
How does a defibrillator work?
Depolarizes all parts of ventricular myocardium simultaneously, 3-5 seconds later heartbeat restarts
What is asystole?
Ventricular Standstill
Define commotio cordis.
Vfib + blow to chest = Death
What part of the waves do you need to watch for in commotio cordis?
Just before T Wave
What do tall P waves in II, III, and aVF mean?
R Atrial Hypertrophy
What do two-peaked P waves in I mean?
L atrial hypertrophy
Five causes of R Ventricular Hypertrophy?
Valve Stenosis Tricuspid Insufficiency Pulm. Hypertension Septal defect Fallot
How do you diagnose Left Ventricular Hypertrophy?
Echocardiography
Difference in observations of 1st, 2nd, and 3rd degree AV block
1 – Slowing
2 — Some Dropped
3 – Atrial and Ventricular contraction are unrelated
Mobitz I, II, and 2:1 II.
M1 – PR increases till beat drops
M2 – PR normal, QRS sometimes dropped
2:1M2 – 2 Ps per QRS
Causes of AV block?
Ischemia, Compression, Inflammation, diptheria/rheumatic fever, Vagus
Why is Mobitz type II dangerous?
It can progress to complete heart block
Describe L Bundle branch block.
Heart Disease
Wide Rs in I, aVL, or V6
Deep Ss in V1-4
Describe R Bundle branch Block
Wide S in I,
R’>R, but switches as you go from V1-V6
What is LQTS?
Slowed repolarization of cardiac muscle
Leads to Early Afterdepolarizations
Slowed Repolarization allows Ca Channels to reactivate, causing serious tachycardia/fibrillation via torsade de pointes
What is hERG?
A gene forming a major portion of I-Kr ion channels
Mutations delay repolarization, cause LQTS
How can LQTS be acquired?
Anti-arrhythmics, anti-psycholics, antibiotics
Alcoholism, Pericarditis, LV hypertrophy, cocaine
Coronary Artery Disease is the result of….
Atherosclerosis (development of arterial lesions that can lead to narrowing of lumen)
Heart pain that goes away when exertion is over?
Stable Angina
Cause of Acute Coronary syndrome
Disruption of previously non-severe lesion.
Stenosis/Blockage of vessel + myocardial ischemia
What are STEMI and NSTEMI?
STEMI – ACS – ST-Elevated myocardial infarction
NSTEMI – ACS – Non-ST Elevated myocardial infarction
What damage is typically seen in STEMI? NSTEMI?
STEMI – Full Thickness Damage, Prolonged Anginal Pain
NSTEMI – Stenosis, Sub-endocardial ischemia, Unstable Angina
What is Prinzmetal’s variant angina?
Transient coronary vasospasm triggered by atherosclerotic plaque
Ischemia only with anginal pain
Leads associated with Lateral heart (Left Circumflex and LAD arteries)
I, aVL, v5, V6
Leads associated with Inf/Right Coronary?
II, III, aVF
Waves seen within 5 minutes, within 20 minutes, and within an hour of MI
within 5 – Hyperacute T from hyperkalemia
within 20 – ST Elevation
Within 1 hour – QRS elevation
Nickname for ST elevations seen in MIs
Tombstones
What wave difference is often seen long term following MI?
Permanent pathologic Q-wave
