Cardiology- Anatomy and Physiology Flashcards
When does heart start to beat spontaneously
Week 4
Define Kartagener syndrome: what is molecular and developmental loop
L-R asymmetry; defect in cardiac looping; primary ciliary dyskinesia
What does Truncus arteriosus become
ascending aorta, pulmonary trunk
what does the bulbus cordis become
smooth parts (outflow tract) of L and R ventricles
What does the primitive atria become
trabeculated part of L and R atria
What does the primitive ventricle become
trabeculated part of L and R ventricles
What does the primitive pulm vein become
smooth part of L atrium
What do the L and R horn of the sinus venosus become
L horn: coronary sinus
R horn: smooth part of R atrium
What does the common cardinal vein and the right anterior cardinal vein become
SVC
What causes a patent foramen ovale
failure of the septum primum and septum secundum to form
Which part of septum most commonly causes VSD
membranous septum
What are the aortic and pulmonary valves derived from?
Endocardial cushion of outflow tract
What are the mitral and tricuspid valves derived from?
fused endocardial cusions of the AV canal
What are the locations of fetal erythropoiesis (4)
Yolk sac (3-8wks), Liver (6wk-birth), Spleen (10-28wk), Bone marrow (18wk-adult)
What causes difference in affinity between fetal, adult blood?
HbF doesn’t respond to 2,3-BPG
What does the umbilical vein become
Ligamentum teres hepatis (part of falciform ligament)
What does the foramen ovale become
Fossa ovalis
Describe direction of flow of ductus arteriosus prenatally and postnatally
Prenatally: R to L
Postnatally: L to R (not cyanotic)
Describe location of ductus venosus; what does it bypass?
Umbilical vein to IVC (bypasses hepatic circulation)
Describe location of ductus arteriosus
Pulmonary artery (deox blood from SVC) to aorta
What is the purpose of the foramen ovale
Diverts oxygenated blood from IVC to aorta- maximally oxygenated blood reaches head
What is used to close and keep open a PDA
Indomethicin closes
PGE1, PGE2 keeps open
Supply of SA, AV nod
RCA
What are 2 major anastomoses of coronary circulation
RCA+circumflex, PDA+LDA
What is most posterior part of heart; what is consequence?
LA- enlargement can cause dysphagia, hoarseness (recurrent laryngeal)
What is the most anterior part of the heart?
RV
Describe L vs R dominant heart
PDA from RCA= R dominant
PDA from LCX= L dominant
Describe Fick principle
CO=rate of O2 consumption/(arterial O2-venous O2 content)
Formula for pulse pressure, what is it proportional to?
pulse pressure= systolic pressure-diastolic pressure
proportional to SV
How calculate SV
SV=EDV-ESV
What three factors affect SV?
Incr contractility, Incr preload, decr afterload
Blockade of which sympathetic channels decr cardiac contractility
B1, decr cAMP
What approxomates afterload?
MAP
Describe Laplaces law
relates LV size and afterload
wall tension= (pressurexradius)/(2xwall thickness)
What is a normal EF
> 55%
Change in EF for systolic, diastolic heart failure
Decr in systolic HF, normal in diastolic HF
What two factors affect preload
Venous tone, ciruclating blood volume
How do you determine EF?
EF=SV/EDV=EDV-ESV/EDV
Describe starling law
the force of contraction is proportional to the end-diastolic length of cardiac muscle (preload)
Relates SV or CO to Ventricular EDV
Where is the TPR determined?
arterioles
What 3 factors determine resistance
viscosity and vessel length directly proportional
4th power of radius inversely proportional
Describe valves in isovolumetric contraction
Between mitral valve closing and aortic valve opening
Describe valves in systolic ejection
Between aortic valve opening and closing
Describe valves in isovolumetric relaxation
between aortic valve closing and mitral valve opening
Describe rapid filling
Just after mitral valve opening
Describe reduced filling
just before mitral valve closing
What makes S1 sound, when does it occur
Mitral and tricuspid valve closure
Beginning of systole
What makes S2 sound, when does it occur
aortic and pulm valves closing
beginning of diastole
What makes S3 sound- when is it, what causes it?
During rapid ventricular filling phase
Incr filling pressures, dilated ventricles
What populations can have a normal S3 sound?
Children, pregnant women
When does S4 occur, what causes it?
Late diastole
“atrial kick”= High atrial pressure
associated with ventricular hypertrophy
JVP- Describe: a wave c wave x descent v wave y descent
a wave- atrial contraction
c wave- RV contraction (bulging tricuspid)
x descent- atrial relaxation
v wave- incr RA pressure, filling against closed tricuspid valve
y descent- flow from RA to RV
What JVP changes are seen in tricuspid regurgitation
No x descent
What conditions cause wide splitting?
Delayed RV emptying: pulmonic stenosis, RBBB
What condition causes fixed splitting?
ASD (incr RA, RV volumes; delayed pulmonic closure)
What conditions cause paradoxical splitting?
Delayed LV emptying: aortic stenosis, LBBB
Holosystolic, high-pitched “blowing murmur”
Loudest at apex, radiates toward axilla
Mitral Regurgitation
Holosystolic, high-pitched “blowing murmur”
Loudest at L sternal, 5th intercostal, radiates to R sternal border
Tricuspid Regurgitation
Crescendo-decrescendo systolic ejection murmur
Loudest at heart base, radiates to carotids
Aortic stenosis
Causes of aortic stenosis
age-related calcification, bicuspid aortic valve
Causes of mitral regurg
ischemic heart disease, MVP, LV dilation
Holosystolic, harsh-sounding murmur
Loudest at tricuspid area, accentuated with hand grip
VSD
Late systolic crescendo murmur with midsystolic click
Heard over apex
Mitral valve prolapse
High-pitched “blowing” early diastolic decrescendo murmur
Aortic regurgitation
Opening snap, Delayed rumbling late diastolic murmur
Mitral stenosis
Continuous machine-like murmur
Loudest at S2
Best heard at left infraclavicular area
PDA
Describe channels: Ventricular Action potential Phase 0 Phase 1 Phase 2 Phase 3 Phase 4
Ventricular Action potential
Phase 0- voltage-gated Na+ channels open, rapid depol
Phase 1- Inactivation Na, K channels open, initial repol
Phase 2- Ca2+ influx (via voltage-gated Ca2+) balances K+ efflux
Phase 3- massive K+ efflux (opening voltage-gated slow K+)
Phase 4- high K+ permeability
What is the resting membrane potential of ventricles vs pacemakers?
Ventricle: -85mV
Pacemaker: -70mV (Na+ channels permanently closed)
Describe channels: Pacemaker action potential Phase 0 Phase 1 Phase 2 Phase 3 Phase 4
Pacemaker action potential:
Phase 0- opening voltage-gated Ca2+- slow upstroke
Phase 2- Absent
Phase 3- Inactivation Ca2+, activation K+…K+ efflux
Phase 4- If(Na+)- spontaneous depolarization as Na+ conductance increases
What channel determines the HR
Slope of If Na channel of pacemaker cells
What is the effect of Ach/Adenosine on HR, If channel
Decr rate of depolarization, Decr HR
What is the PR interval, what is a normal length
Conduction delay of AV node, <200msec
What is the QRS complex, what is a normal length
ventricular depolarization, <120msec
What is T wave?
Ventricular repolarization
What does a T wave inversion indicate
Recent MI
What causes a U wave?
Hypokalemia, bradycardia
Polymorphic ventricular tachycardia: shifting sinusoidal waveforms on ECG
Torsades des pointes
Treatment of Torsades de pointes
Mg sulfate
Romano-Ward syndrome
Congenital long QT syndrome: AD, pure cardiac defect
Jervell and Lane-Nielsen syndrome
Congenital long QT syndrome: AR, sensorineural deafness
ECG finding: shortened PR interval with delta wave
Wolff-Parkinson-White syndrome (ventricular pre-excitation syndrome: bypass of AV node)
ECG: Chaotic and erratic baseline with no discrete P waves
A fib
ECG: A rapid succession of identical, back-to-back atrial depolarization waves (sawtooth)
Atrial flutter
ECG: Completely erratic rhythm with no identifiable waves
Ventricular fibrillation
ECG: Prolonged PR interval
1st degree AV block
ECG: progressive lengthening of PR interval until a beat is “dropped”
Mobitz type I 2nd degree AV block (Wenckebach)
ECG: Dropped beats that are not preceded by a change in the PR interval; often 2:1 block
Mobitz type II 2nd degree AV block
ECG: Both P waves and QRS complexes are present, but they have no relation to each other
3rd degree AV block
What is the pharmacological treatment for atrial flutter?
class IA, IC or III antiarythmics
What severe ECG change can Lyme disease cause
3rd degree heart block
What releases ANP, what causes?
atrial myocytes, incr blood volume, atrial pressure
What is the action of ANP on kidney?
Vasodilaiton, decr Na+ reabsorption in collecting tubule
constricts efferent and dilates afferent
What releases BNP, what causes?
Ventricular myocytes, incr tension
Nesiritide
recombinant BNP, used to treat heart failure
What does PCWP approximate? What is normal?
L atrial P, <12
What nerve transmits aortic arch? What is the nucleus?
Vagus nerve, solitary nucleus
What nerve transmits carotid sinus? What is the nucleus?
glossopharyngeal nerve, solitary nucleus
What is response of Aortic arch and carotid sinus to BP changes?
Aortic arch: only responds to incr BP
Carotid sinus: responds to incr and decr BP
What is the appropriate response to carotid massage?
Decr HR
What do peripheral chemoreceptors respond to?
Decr PO2, Incr PCO2, decr pH
What do central chemoreceptors respond to?
pH and PCO2 (not PO2)
What local metabolites autoregulate the heart?
CO2, adenosine, NO
What local metabolites autoregulate the brain?
CO2
What local metabolites autoregulate skeletal muscle?
lactate, adenosine, K+, H+, CO2
Formula for starling forces of capillary fluid exchange
Pnet=(Pc-Pi)-(pc-pi)
