Cardio Flashcards
Sinus venosus gives rise to?
Left horn = Coronary sinus
Right horn = smooth RA
What contributes to the septation of both atria and ventricles?
Endocardial cushion= NC origin
MC septal defect in children vs adults?
Children = VSD (Fetal alcohol, Tetralogy, Cri-du-chat)
Adults= ASD
occurrence: VSD > ASD > PDA
Fetal erythropoiesis timeline?
Yolk sac–> Liver–> spleen –> BM
CO in early vs late exercise?
Early= inc CO = Inc HR X inc SV Late = Inc CO = inc HR x stable SV (plateau)
CO equations?
CO= HR x SV CO= O2 consumption/ (arterialO2- venousO2)
MAP calculation?
MAP= CO x TPR MAP = 2/3 diastolic pressure + 1/3 systolic
Pulse pressure calculation?
PP = systolic pressure - diastolic pressure
** Proportional to SV
Increase in SV increases what?
Pulse pressure
**Aortic regurgitation= Inc SV = High PP
SV calculations?
SV = CO/HR = EDV-ESV
What are the determinants of Myocardial O2 demand?
Afterload
Preload= Heart size = Wall tension (hypertrophy)
HR
Contractility
How can you decrease Myocardial O2 demand?
Nitroglycerin = Dec Preload= Dec wall tension (inc BF)
ACEi/ Ca channel blockers = Dec Afterload
B-blockers= dec HR = GIVE after MI
Control HTN/ Aortic stenosis= dec Hypertrophy
EF calculation?
EF = (EDV- ESV) / EDV
**Normal EF = >55%
Equation for Resistance in SERIES?
R = Sum of all Rs
**Total should be Higher than individual
Equation for Resistance in Parallel?
1/Rt = 1/r + 1/r + 1/r
**Sum of all Should be lower than Individual Rs
Equation for Resistance?
R = Pressure/ Q (flow) = (viscosity x length)/ r>4
**R directly proportional to = Pressure/viscosity/length
What factors change change the mean systemic filling pressure (x intercept of CV function curve)?
Volume or Venous compliance
- *Increase volume or Dec Compliance = Inc MSFP
- *nitroglycerin inc Compliance = Dec MSFP
What factors affect venous return?
SVR –> Dec SVR= Inc VR
**Arterioles dilate= Inc BF to veins = Inc VR
S3 is associated with what?
Inc Filling pressure (Mitral regurg + CHF)
**Normal in Children or Pregnant women
JVP graph: a wave = c wave = x descent = v wave = y descent=
a = Atrial contraction c = RV Contraction x = atrial relaXation v = Inc RA pressure due to filling y = BF from RA -> RV
S1 & S2 splitting:
Wide=
Fixed=
Paradoxical=
Wide= Delay RV emptying (Pul stenosis, RBB block)
Fixed = ASD
Paradoxical = LV emptying delay (Aortic stenosis, LBB blck)
**Inspiration will fix Paradoxical due to late closure of Pulmonic valve due to Inc VR
Hand grip (Inc SVR) affects what murmurs and How?
Inc SVR= Inc intensity (MR, AR, VSD, MVP)
Inc SVR= dec intensity (AS, HCM)
**Makes sense= Inc SVR means LV SV will try and go somewhere other than Aorta (lower pressure)
Valsalva affects what murmurs and how?
Valsalva = Inc Thoracic pressure = Dec VR
Inc Intensity = MVP + HCM
Pt has a murmur that intensifies with Valsalva?
MVP
HCM
Rapid squatting affects what murmurs and how?
Rapid squatting = Inc VR/preload + prolonged (inc AL)
Dec = MVP + HCM
What kind of patients squat in order to improve circulation/ murmur?
Tetralogy = Inc VR = Inc pressure in RV so less Left->R shunt through VSD HCM= Inc VR dec the Aortic stenosis by Septum/ MV
In cardiac myocyte @ resting potential what Ion has Highest permeability?
K+
What Ion is responsible for Myocyte depolarization vs Pacemaker depolarization?
Myocyte= Fast Na channels Pacemakers= Calcium channels
What are the phases of Cardiac myocyte APs?
P0= Fast Na channels open = Depol P1= Na channels close/ K channels open P2= Ca channel open Balance K efflux= Plateau/ contraction P3= K channel all open / Ca channels close P4= Resting K dominates
What happens to Cardiac nodal cells during diastole?
They depolarize via If “funny” Na channels
What are the phases of Cardiac Pacemaker action potentials?
P0 = Ca channels open = Upstroke/ Depol P1/2= Absent P3= Ca channels inactive/ K channels open= Repol P4= Slow diastolic spontaneous depol via Na channels
What part of the Pacemaker action potential determines the HR?
Na channel / Phase 4 SLOPE
- *Adenosine/Ach= Dec P4 slope= dec HR
- *NE/E = Inc P4 slope = Inc HR
- SNS increases Na channel opening = Inc HR
Electrocardiogram: QT interval= PR interval length= ST = U wave =
QT = Mechanical contraction of ventricles PR = <200msec = AV delay ST = Isoelectric ventricle depol U = Hypokalemia, bradycardia
What is the order of Speed of conduction?
Purkinji> atria > ventricles > AV