HEMODYNAMIC ASSESSMENT: CARDIAC CATHETERIZATION

LABORATORY

William Hellenbrand MD

Director, Pediatric Cardiology

Morgan Stanley Children’s Hospital of New York - Presbyterian

Columbia University Medical Center

Komansky Center for Children’s Health

Cornell University Medical Center

CARDIAC CATHETERIZATION

• Cardiac output

• Shunt & Resistance

• Oxygen transport

• Pressure-Volume loops

FICK PRINCIPLE• The amount of flow through an organ or any circuit

may be determined if • 1 - that organ consumes or secrets a given

substance• 2 - the concentration of that substance can be

measured as it enters and leaves the organ• 3 - The total amount of the substance consumed or

secreted can be measured per unit time

∆S/∆t

C2S – C1S

FICK PRINCIPLE

OXYGEN IN BLOOD

• When oxygen is exposed to blood it exists in 2 forms

Bound to hemoglobin

Each gram of Hgb is capable of binding 1.36 ml O2.

Therefore if the Hgb is 15 gm/100ml then the maximal amount of oxygen(Capacity) that can be taken up by Hgb is 20.4 ml/100ml(Vol%)

OXYGEN IN BLOOD

• When oxygen is exposed to blood it exists in 2 forms(cont)

• In solution in plasma – At body temperature of 370 , there

is .00003 ml of O2 per one ml of plasma at a partial pressure of oxygen of 1 mm Hg(1 torr)

Thus the solubility coefficient of oxygen in plasma is 0.00003 ml/ml/mm Hg

Therefore the amount of dissolved oxygen in plasma is equal to .003(PO2)

OXYGEN IN BLOOD

• Oxygen capacity = Hgb(gm/100ml)*1.36 ml O2/gm = ml O2/100ml (Vol%)

• Oxygen saturation = proportion of O2 actually combined with hemoglobin to the total capacity

• Oxygen content = Capacity*Saturation + .003*PO2

= ml/100ml (Vol%)

OXYGEN CONSUMPTION

• VO2 = VIFIO2 - VEFEO2

• If RER is 1 then VI = VE and all you need to measure is VEFEO2

• RER = VCO2 / VO2

– RER is close to 1 with carbohydrate metabolism– RER may be as low as 0.7 with mostly fat

metabolism– Standard nomograms assume RER of 0.9

Oxygen Consumption

CARDIAC OUTPUTSYSTEMIC BLOOD FLOW

Qs = VO2 CaoO2 - CmvO2

Qp = VO2 CpvO2 - CpaO2

If there is no shunt Qp = Qs

SHUNT CALCULATIONS

• Qs = VO2

CaoO2 - CmvO2

• Qp = VO2

CpvO2 - CpaO2

• Qep = VO2

CpvO2 - CmvO2

• SIMPLE SHUNT– Ql-r = Qp - Qs

– Qr-l = Qs - Qp

• BIDIRECTIONAL SHUNT– Ql-r = Qp - Qep

– Qr-l = Qs - Qep

SHUNT CALCULATIONS

RESISTANCE TO FLOW

• Poiseuille equation

Q = ∆Pπr4 1 = 8nl R

∆P = pressure drop

r = radius Q = ∆P

n = viscosity R

l = length of tube

πr4

8nl

R = ∆P

Q

RESISTANCE

• SVR = AO(MEAN) - RA(MEAN)

Qs

• PVR = PA(MEAN) - LA(MEAN)

Qp

SYSTEMIC OXYGEN TRANSPORT(SOT)

SOT = Q X OXYGEN CONTENT

SOT = Q X [(1.36 X Hgb X O2 SAT) + (.003 X PO2)]

SYSTEMIC OXYGEN TRANSPORT(SOT)

SOT = Q X [(1.36 X Hgb X O2 SAT) + (.003 X PO2)]

Anemic Hypoxia: HgbSOT Acute compensation Q SOT Chronic compensation HgbSOT

SYSTEMIC OXYGEN TRANSPORT(SOT)

SOT = Q X [(1.36 X Hgb X O2 SAT) + (.003 X PO2)]

Hypoxic Hypoxia: 02 SAT SOT Acute compensation Q SOT Chronic compensation Hgb, Q SOT

SYSTEMIC OXYGEN TRANSPORT(SOT)

SOT = Q X [(1.36 X Hgb X O2 SAT) + (.003 X PO2)]

Stagnant Hypoxia: Q SOT (Low Cardiac Output)

Compensation Hgb, 02 SATSOT

VSD

M=6

M=8

80/6

80/40M=60

80/50M=65

70

70

85

80

80

95

VSDRoom Air

• Hgb = 10.0 Vol%• V02 = 150 ml/min/m2• Saturations

– Svc = 70– Ra = 70– Rv = 85– Pa = 80– Ao = 95

• Pressures– Ra = 6(mean)

– Rv = 80/6

– Pa = 80/40 60(mean)

– La = 8(mean)

– Ao = 80/50 65(mean)

VSDRoom Air

• Capacity = 1.36*10 = 13.6

• Contents = – Ao =13.6*.95=12.9

– Mv = 13.6*.70=9.5

– Pa = 13.6*.80=10.9

– Pv = 13.6*.95=12.9

• S(a-v)02 difference = 3.4

• P(a-v)02 difference = 2.0

• Qp = 150/2.0

– = 7.5 l/min/m2

• Qs = 150/3.4

– = 4.4 l/min/m2

• Ql-r = 7.5-4.4=3.1

• Qp/Qs = 7.5/4.4=1.7

• PVR =(60-8)/7.5 =6.9

• SVR =(65-6)/4.4=13.4

VSDfI02 = 1.0

• Hgb = 10.0 Vol%

• V02 = 150 ml/min/m2

• Saturations– Svc = 75 (45)

– Ra = 80

– Rv = 94

– Pa = 95 (85)

– Ao = 100 (600)

• Pressures– Ra = 6(mean)

– Rv = 80/6

– Pa = 80/40 60(mean)

– La = 8(mean)

– Ao = 80/50 65(mean)

VSD fI02 = 1.0(PO2 not included)

• Capacity = 1.36*10 = 13.6

• Contents = – Ao =13.6*1.0=13.6

– Mv = 13.6*.75=10.2

– Pa = 13.6*.95=12.9

– Pv = 13.6*1.0=13.6

• S(a-v)02 difference = 3.4

• P(a-v)02 difference = 0.7

• Qp = 150/0.7

– = 21.4 l/min/m2

• Qs = 150/3.4

– = 4.4 l/min/m2

• Ql-r = 21.4-4.4=17.0

• Qp/Qs =21.4/4.4=>4/1

• PVR =(60-8)/21.4 =2.4

• SVR =(65-6)/4.4=13.4

VSD fI02 = 1.0(PO2 included)

• Capacity = 1.36*10 = 13.6

• Contents = – Ao =13.6*1.0+1.8=15.4

– Mv = 13.6*.75+.15=10.4

– Pa = 13.6*.95+.25=13.2

– Pv = 13.6*1.0+1.8=15.4

• S(a-v)02 difference = 5.0

• P(a-v)02 difference = 2.2

• Qp = 150/2.2

– = 6.8 l/min/m2

• Qs = 150/5.0

– = 3.0 l/min/m2

• Ql-r = 6.8-3.0=3.8

• Qp/Qs = 6.8/3.0=2.3

• PVR =(60-8)/6.8 =7.6

• SVR =(65-6)/3.0=20.0

VSD

• P02 not included• Qp = 150/0.7

– = 21.4 l/min/m2

• Qs = 150/3.4– = 4.4 l/min/m2

• Ql-r = 21.4-4.4=17.0• Qp/Qs =21.4/4.4=>4/1• PVR =(60-8)/21.4 =2.4• SVR =(65-6)/4.4=13.4

• P02 included• Qp = 150/2.2

– = 6.8 l/min/m2

• Qs = 150/5.0– = 3.0 l/min/m2

• Ql-r = 6.8-3.0=3.8• Qp/Qs = 6.8/3.0=2.3• PVR =(60-8)/6.8 =7.6• SVR =(65-6)/3.0=20.0

VALVE AREA CALCULATION

VALVE AREA CALCULATION

VALVE AREA CALCULATION

OXYGEN DISSOCIATION CURVE

OXYGEN DISSOCIATION CURVE

OXYGEN DISSOCIATION CURVE

PRESSURE-VOLUME LOOPS

P-V LOOPS

P-V LOOPSPump Failure

P-V LOOPSPump Failure

P-V LOOPS