Other

Question 1

Control of myocardial O2 supply

Answer 1

coronary arterioles
o Normal heart: 60-80% of capillaries are open
o Arterial hypoxia: recruitment of capillaries

Question 2

Major determinants of myocardial O2 demand

Answer 2

• HR => acutely regulate contractile state (w Starling law and autonomic control
  o incr O2 demand by incr external work + enhancing force of ventricular contraction
   Bowditch staircase effect: force frequency relationship
   Rapid stimulation => incr intra¢ Na+ and Ca2+ => overload Na+/K+ pump => Na+ overload incr Na+/Ca2+ exchanger fct => incr Ca2+ => incr inotropy
• Myocardial wall stress => afterload
• Velocity of contraction => contractility
  o incr contractility => incr velocity of contraction
   Adrenergic stimulation
   Digitalis
   Inotropic agents

Question 3

Indices of myocardial O2 uptake

Answer 3

• HR
• Double product
  o Systolic pressure x HR
• Triple product
  o Systolic pressure x HR x systolic ejection time
• Time-tension index (or time-pressure)
• Pressure-volume area
• Pressure-work index: integral of pressure and flow during ejection period

Question 4

Myocardial metabolism

Answer 4

• Fatty acids: major source of E
  o Anaerobic glycolysis: max 5-7% of normal E requirements
• Limited energy reserve => require high rate of ATP production + continuous O2 supply

Question 5

phases of the Valsalva maneuver

Answer 5

• Forceful expiration against closed glottis => incr intrathoracic pressure (contracting rib cage)
  o decr venous return + compression of cardiac chambers => decr cardiac filling/preload => decrCO
  o Compression of thoracic Ao => incr Ao pressure for few seconds (phase I)
   decr Ao pressure after 2nd to decr CO (phase II)
  o BaroR reflex: reciprocal changes in HR
   Phase I: decr HR because of incr BP
   Phase II: incr HR because of decr BP
• When normal breathing is restored => removal of external compression
  o Brief decr Ao pressure + HR (phase III)
  o incr cardiac filling pressures => incr CO => incr Ao pressure + decr HR as CO decr
  o BaroR + adrenergic incr in PVR also incr Ao pressure

Question 6

Anrep effect

Answer 6

• Acute incr afterload (BP) => incr contractility
  o Intrinsic change in inotropy
  o incr afterload => incr LV end diastolic volume (decr CO) => incr inotropy through Frank Starling mechanism
   If maintained => contraction force incr further (10-15min) => decr end diastolic volume
  o Partially compensate incr end systolic volume and decr SV 2nd to incr afterload
• Initial response: Frank Starling => incr TnC sensitivity to Ca2+
• Delayed response: promote incr Ca2+ release by SR
  o Mediators: ET1, Ang II released by cardiac cell in response to stretch
  o incr LV wall tension => myocardial mechanoR => incr cytosolic Ca2+

Question 7

Austin Flint murmur

Answer 7

DYING WHALE
* Severe AI => mid-diastolic to presystolic murmur
o Premature MV closure => disturbed diastolic flow through MV orifice/ bulging
o Best heard at L apex
o S1 soft, S2 obscured by soft regurgitant murmur and louder, low pitched late diastolic murmur

Question 8

Bainbridge reflex

Answer 8

• incr atrial pressure => stretch R at jct of PVs => incr HR
  o ↑ blood volume → incr venous return => ↑ β fiber firing → signals to brain → modulation of ∑ and p∑ influence on SA node → ↑ HR → incr CO
   Small effect on contractility and SV: incr SV through Frank Starling
   incr HR through ∑ stimulation
  o Blocked by atropine or cutting vagus nerve
• Involved in sinus arrhythmia: inspiration → ↓ intrathoracic P → ↑ venous return → ↑ stretch R stimulation → Bainbridge reflex → ↑ HR

Question 9

Bezold-Jarisch reflex

Answer 9

• Powerful vagal reflex
  o Reflex bradycardia: slow SA node PM + 2AVB Mobitz I
  o Vasodilation and hypotension
   Renin release
   Vasopressin secretion
  o ↑ coronary flow
• Cardiac sensory R in LV, inferoposterior wall
  o Stimulated by stretch, chemical substances, drugs
   symp overactivity: ↓ preload, myocardial infarction → contraction of under filled LV
  o Sense underfilled LV → activate high pressure C fiber afferent nerve → non myelinated vagal afferent signals: incr psmp, decr symp → paradoxical bradycardia + ↓ contractility → hypotension
• Treated w volume repletion and atropine

Question 10

Branham reflex

Answer 10

• Sudden occlusion of AV fistula/shunt → sudden ↑ in BP → bradycardia
  o Exaggerated Bezold-Jarish reflex
  o Shunt closure → excess CO forced into systemic circulation → sudden ↑ in diastolic BP → baroR stimulation → bradycardia

Question 11

Brockenbrough-Braunwald-Morrow sign

Answer 11

• Hemodynamic technique to diagnose DLVOTO
  o ↓ in BP after VPC + ↑ in peak LVP
• Normally: VPC will cause post extrasystolic potentiation
  o Compensatory pause → longer filling period → ↑ LV end diastolic volume → ↑ SV and BP

Question 12

Rivero-Carvallo sign

Answer 12

• TV: indicate TR or TS
• Louder murmur during inspiration
  o Inspiration → ↓ intrathoracic P → ↑ venous return → ↑ R heart filling → ↑ regurgitant volume
  o TR: ↑ fillinf → ↑ regurgitatnt volume
  o TS: ↓ P in RV > vs RA → ↑ PG and filling force → louder murmur
• Helps distinguish MR from TR

Question 13

Bowditch staircase effect or Treppe effect

Answer 13

• incrHR => incr contractility
  o Positive inotropic effect of activation or force-frequency relationship
  o incr Na+ and Ca2+ entry => overload Na+/K+ pump => incr [Na2+] => Ca2+ entry by Na+/Ca2+ exch

Question 14

Corrigan’s pulse

Answer 14

• Bounding or water-hammer pulse: large and strong pulse w normal contour
  o PDA, AI, peripheral AV fistula : ↑ pulse pressure 2nd to diastolic runoff

Question 15

Frank-Starling law

Answer 15

• Frank : incr diastolic heart volume => ventricular stretch → incr contraction velocity + force = + inotropic effect
• Starling: energy of contraction is a fct of the initial length of the muscle fiber
  o incr venous pressure => incr stretch fiber at end of diastole => incr contraction force
• Frank-Starling: ability of heart to change its force of contraction and SV in response to venous return
  o incr venous return => incr ventricular filling/end diastolic volume => incr initial stretching of myo¢ => incr sarcomere length => incr inotropy + SV
  o incr preload => incr active tension on muscle fibers => incr velocity of fiber shortening
  o incr sarcomere length => incr TnC Ca+ sensitivity => incr cross bridge attachment/detachment
• Normal curve: red dashed
  o Afterload and inotropy define slope of curve
   ↑ afterload or ↓ contractility → shift down and R → ↓ SV
   ↓ afterload or ↑ contractility → shift up and L → ↑ SV
  o Preload/volume define position on normal curve

Question 16

Kussmaul’s sign

Answer 16

• incr jugular venous pressure w inspiration
  o Indicative of limited RV filling due to R heart dysfct => incr blood flow backup into venous system => jugular venous distension
  o DDX: constrictive pericarditis, RCM, RV infarctus, cardiac tumor, TV stenosis, PTE
• Normally = inspiration => decr intrathoracic pressures => incr venous return in highly compliant RA
• Kussmaul breathing: deep and labored breathing 2nd to severe metabolic acidosis (DKA, Kid failure)
  o Hyperventilation: ↓ CO due to ↑ rate and depth of respiration

Question 17

Graham Steele murmur

Answer 17

• PV: associated w/ PI
  o Louder, higher pitched, decrescendo
  o Earlier in diastole
  o Best heard at L apex after S2
• icnr intensity w inspiration unlike AI murmur
  o decr w vagal stimulation
• Associated w/ PH >55mmHg → dilation of PV annulus → PI

Question 18

Cushing reflex

Answer 18

• Cranial perfusion pressure = mean BP – intracranial BP
  o Cranial blood flow = cranial perfusion pressure/cranial vascular resistance
• incr ICP => compression of brain/arteries => CNS ischemic response => incr BP → ↑ cerebral blood flow
  o ∑ system response:
   Activation of A1R => peripheral vasoconstriction => incr BP
   incr HR + contractility => incr CO
  o p∑ response: BaroR in Ao arch detect icnr BP => reflex bradycardia via vagal stimulation
  o Distortion of brainstem 2nd to icnr ICP => loss control of involuntary breathing => irregular respiratory pattern/apnea
• Leads to triad
  o Irregular, decr/slow repiration
  o Bradycardia
  o Widening pulse pressure, systolic hypertension

Question 19

Seldinger technique

Answer 19

• Vascular access technique: vessel is puncture w needle/KT => guidewire advanced through lumen => sheath/cannula passed over guidewire

Question 20

Guyton curves

Answer 20

• Guyton: important research on cardiovascular physiology and author of textbook (AKA part of general boards trauma) → discovered need for tissue O2 determines CO and BP regulation by kids
• Guyton curves: describe relation ship btwn RAP and CO
  o Venous return: ↓ as RAP ↑
   Curve slope = resistance to venous return
  o Cardiac function curve:
  o Mean circulatory filling P: BP at which venous return is 0
  o Intersection of venous return curve and CO → functioning preload of RV

Question 21

Lewis-Wigger diagram

Answer 21

Cardiac cycle diagram: LV contraction, relaxation, filling

Question 22

Harvey

Answer 22

1st physician to describe systemic circulation and blood pumped from the heart

Question 23

Sones

Answer 23

1st to develop cardiac angiography + 1st coronary bypass sx