Hemodynamics (Part 1) Flashcards
What does the P wave represent?
Artial depolarization
What does P-R interval represent?
Beginning of P wave to beginning of QRS
What does the ST segment represents?
Represents the period when the ventricles remain depolarized
What does the T wave represent?
Represents ventricular repolarization
What is the flow of Cardiac Conduction?
SA node–> AV node–> Bundle of His–> Bundle branch (LBB & RBB)–> Purkinje fibers
What is the conduction pathway (bpm) of the cardiac system?
SA (60-100 bpm)
AV (40-60 bpm)
Ventricle (20-40 bpm)
What does the ECG show?
Electrical activity of the heart (recorded by skin electrodes)
What happens during diastole?
ventricles empty and relax
Tricuspid and mitral valves open
Blood leaves the atria and fills the ventricles
What happens during systole?
Ventricles contract
Increasing BP in ventricles forces (mitral tricuspid) valves closes
Pulmonic & Aortic valves open
Blood is ejected from ventricles into pulmonary artery and aorta
How long is the cardiac cycle?
Ventricular contraction (systole)— 1/3 of the cycle
Ventricular relaxation (diastole)— 2/3 of the cycle
What effect does rapid HR have on filling time?
Ventricles fill during diastole
The ventricles doesn’t fill as much and doesn’t eject as much blood so diastolic time shortens
What process happens first, Electrical or mechanical?
The electrical occurs first then mechanical
What does the arteries do?
Carries blood AWAY from the heart
What does veins do?
Carries blood towards the heart
How many layers does the heart have?
3-Epicardium, myocardium, endocardium
What is the myocardium composed of?
TEST Q
Its the middle and most prominent layer that’s composed of cardiac muscle
What valves close to make the S1 sound?
Tricuspid and mitral valves
How does the blood flows through the heart?
Superior vena cava–>R-artium–> tricuspid valve–> R-atrium–> pulmonic valve–> pulmonary artery–> lungs–> pulmonic veins–> L-artium–> mitral valve–> L-ventricle–> aortic valve
What valve control blood flow from L-artium/L-ventricle
TEST Q
Mitral valve
What does Sinus Bradycardia look like?
HR less than 60bpm (originating form the sinus node)
Regular rhythm
P wave for each QRS
What is Sinus Tachycardia?
What are the causes? (Test Q)
Heart rate >100bmp, originating from th SA node
Regular rhythm
Rate (100-180 bpm)
P wave for each QRS
PR interval regular
Causes: fever/infection, stress, exercise, fear/anxiety, drugs, pain, anemia, low BP, hypothermia (TEST Q)
What does Atrial Fibrillation (A-fib) look like?
Disorganized, uncoordinated twitching of atria muscles caused by rapid production of atrial impulses
Rate may be rapid (uncontrolled-over 100bpm) or slower (controlled-under 100bpm)
How does A-fib look on an EKG/monitor?
P wave not identifiable, irregular baseline (irregular irregular)
PR interval not measurable
Patients may be asymptomatic
No A-V synchromy
What does the loss of AV synchrony result in?
Decreased ventricular filling
How would A-fib be described as?
irregularly irregular,
no identifiable P waves (so no organized atrial depolarization)
narrow QRS
How would A-flutter be described?
Abnormal rhythm that occurs in atria. Atrial rhythm is regular, but fast.
Sawtooth appearance
Atrial rate: 250-400 bpm
QRS complexes uniform in shape, irregular in rate (more Ps than QRS)
*No A-V synchrony
*Anticoagulation may be necessary (pooling of blood in atria)
What is etiology behind AV blocks?
Conduction defects within the AV junction that impair conduction of artia impulses to ventricular pathways
What are the type of AV blocks?
1st Degree
2nd Degree (I or II)
3rd degree
What is different about rhythms above the AV junction?
What about below the AV junction?
They usually have a narrow QRS (ABOVE)
They usually have a WIDE QRS (below)
What does a 1st AV block look like?
Regular rate (60-100 bpm)
PR interval is regular but PROLONGED (> 0.2 secs)
Pts are ASYMPTOMATIC
Management: correction of underlying cause
What does a 2nd degree AV type II (Mobitz II)
block look like?
ATRIAL rhythm regular
VENTRICULAR rhythm
can be regular or irregular
QRS periodically absent or disappears (IMPORTANT DIFFERENCE)
Management: Transvenous pacemaker (or transcutaneous) is needed because this rhythm can rapidly progress to complete heart block
treat underlying cause
atropine
What does 3rd degree heart block looks like?
Artial & ventricular rhythm regular (but ventricular slower)
No relation between P waves and QRS complexes
No constant PR interval, QRS normal or wide/bizarre
Pt. will need a pacemaker
Symptoms: HTN, angina, HF
What does a junctional rhythm look like?
Originates from AV node
Narrow complex (normal QRS conduction)
P wave absent (IMPORTANT DIFFERENCE)
Junctional rhythm (40-60bpm)
Loss of AV synchromy!!
Management: treat cause if possible, meds, may require permanent pacemaker
What are ventricular rhythms?
V-tach or V-fib
What does Ventricular tachycardia (V-tach) looks like?
Any rhythm faster than 100 bpm with 3 or > irregular beats in a row that originates distal to the Bundle of His
Responsible for most of the sudden cardiac deaths in the US
May try medications or synchronized cardioversion
Pulseless- treatment is IMMEDIATE DEFIBRILITION
What does V-fib look likes?
Disordered electrical activity causes ventricles to quiver instead of contracting normally
w/o treatment, FATAL in mins
Treatment: immediate defib, followed by anti-arrythmic meds
Surviviors will likely require placement of implantable cardioverter-defibiliator (ICD)
Most identified arrhythmia in cardiac arrest patients. Survival rate low (particularly out of hospital).
Coarse easier to convert.
What does Pre-mature Ventricular Contractions (PVCs) looks like?
One of the most common dysrhythmias
Can occurs in pts. with or without heart disease
Clinical significance depends on frequency, complexity, and hemodynamics response
What does Pre-mature Artial contractions (PACs)?
Contractions of the atria that are triggerede by artial myocardium, but don’t originate from SA node
Typically have normal QRS complex
Often symptomatic
What does a 2nd degree AV type I (Mobitz I)
block look like?
Atrial regular
Ventricular irregular
PR interval progressively lengthens w/ each cycle until QRS is dropped a cycle
Pts. can be asymptomatic or cause weakness
Management: treat underlying cause, atropine or temp pacemaker if symptomatic
