assessment for operability of chd with pah r. tandon

Assessment for operability of CHD with PAH

R. Tandon

CONGENITAL HEART DISEASE

8 to 10 / 1000 live births

Uncorrected – 30 % PAH

PPH of new born

Idiop. Ped. PAH

L > R Shunt with PAH

Acyanotic CHD - PDA- VSD

- AVSD- AP Window- ASD

Cyanotic CHD with ↑ Qp (Transposition physiology)

Cyanotic CHD with ↑ Qp(Transposition physiology)

Complete TGA DORV, ↑ Qp TA, ↑ Qp PTA SV, ↑ Qp TAPVC Miscellaneous malp. without

obstr. to pulm. blood flow

Congenital Heart Disease

Pulm. Circ: PAH CHD -↑ QP, ↑ Pr, ↑ O2 sat, ?? Hypoperf, 2° to under development Blood Viscosity Thrombo–embolic obstr. Aorto–pulm. Collat.


Pulm. hypertension :PA Pr. = Pulm flow x

PVRHyperkinetic = flowObstructive = PVR

Principles

Low resistance pulmonary circuit1) Qp2) Vol. overload

High resistance pulmonary circuit1) Curtailment of Qp2) Loss of volume loading


PAH :

Hyperkinetic - PVR normal Obstructive - PVR ↑ Due to PVH - PVR normal, ± ↑


Pulmonary Hypertension : dx

PA (m) ↑ 25

PAW/LAm/LVedp 15 mm or ↓

PVR ↑ 3u

(Incorrect)

Factors determining development of PVOD

Type of intracardiac defect Age PA Pressure PV Pressure PBF, PAO2

Hypoxia Acidosis Unexplained - ? Genetic suscept.

? Endoth. dysf.


Pulmonary hypertension : Operability• AgeAge• LesionLesion• Physical findingsPhysical findings• Systemic O2 saturation Systemic O2 saturation • Investigations Investigations

o Non-invasiveNon-invasiveo InvasiveInvasive


PVOD : Age

Unknown 3 m Rare 6 m Uncommon 1 yr

Except in TGA physiology


in PVR : Improving symptoms in CCF Improved exercise capacity Cyanosis : Absent,

intermittent, persistent.


PVOD : Lesion

Very early - 3 mTGA Physio., AP window, Comp. AVC defects

Large PDA earlier than VSD (↓ 1 yr). ASD – rare

Hyperkinetic Obstructive

Heart size large normal (except in ASD)

Parasternalhyperkinetic forcible or heaving in ASDimpulse mild in VSD & PDA

Click of PAH absent present

Second sound ASD‑wide & fixed ASD - wide and fixed(P2 accent‑ VSD‑wide & variable VSD - single uated in both) PDA‑paradoxically PDA - normal

splitShunt murmur loud short or absent

Flow murmur present absent

Pulmonary hypertension


PVOD : Syst. O2 saturation L R shunt - 93% - PVR

95%, PVR not excluded TGA physiol. - 85% high flow and low PVR


PVOD ECG : Increasing RVH - Not helpful

X-ray : * Heart size * Pulm. Vasculature

Characteristics changes appear too late.


Pulm. hypertension :Echo assessment :PA syst. pr - GoodPA diast. pr - ReasonablePA mean pr - PoorFor assessment of PVR – cath is gold standard and essential.

Congenital Heart DiseaseInvasive evaluation

Invasive evaluation Hemodynamic study. Pulmonary wedge angiography. Biopsy – Pulmonary histology. Pulmonary vascular compliance.(MRI & intravascular ultrasound)


PAH Cath study: Pressures – RA,RV,PA, PAW, LA/LVED,SA Saturations – SVc, RA,RV,PA,SA VO2, CI, SVR, PVR HR pO2, pH Effect of intervention.

Cardiac Catheterisation

Measurement of PAP Measurement of PVR Vascular Reactivity

PVR = PAm - LAm Qp

If PVR & PAH - pO2 and pH essential.


Flow: (Poiseuille)

ΔP. π r4

Q= 8ŋL


PAH: PA (m) – LA (m) . 8Lη

PVR= Qp π r4

Assumes constant steady flow


Assessment for reactivity : Oxygen Isuprel infusion Nifedipine Prostaglandin SNP, NO.

PVR ↓ 6 units – operable.


Flows: VO2

Qp= PVO2 – PAO2

VO2Qs= PVO2 (SA) – MVO2

Qp= Qs


Pulmonary hypertension : VO2

Must be measured Assumed value cannot be used

For PVR calculation to determine operability.


Flows: Qp/Qs ratio

SAO2 – MVO2

Qp/Qs=

PVO2 – PAO2

Eliminates need to measure VO2


Flows: Qp/Qs ratio

SAO2 – MVO2

PV (SA)O2 – PAO2

Echo: SVLV

SV X HR = QsQp from Qp/Qs


PAH – PVR

Fixed : PVOD Variable: Vasoconstr - 20% pts.


PAH: Operable – PVR ↓ 6u Rest or ac. Inoperable – PVR ↑ 8u testing. Grey zone 7u ±1.


PAH Vasodilat testing :

Identifies - Prognosis- Responders

(utility of CCB)

PULMONARY HYPERTENSIONAC. VASODILAT TESTING All PATIENTS

Contraindications : RV failure Unstable

haemodynamics

• + Ve resp. : PA (m)→ ↓ by 10 mms absolute level ↓ 40 mms

(no ↓ in Co.) 20% ↓ in PApr & PVR


Pulm. hypertension : Reversibility Qp on the basis of assumed VO2 - not reliable

100% : O2–VO2 not known, hence all calculation will be incorrect.

Dissolved O2 - (modifies calculations)


PVOD : O2 study PA saturation increases abnormally giving

increased calculated QP and low PVR.

Fall in PA pressure more reliable. Fall in PA diast. pr may result in lower mean pressure.

Problems with vasodilators

Oxygen - fick’s principle NA - Failure to respond in patients

with reactive airway disease Tolazoline,PG, Ca Block

- Fall in SVR- Arterial hypotension- VP mismatch

Isoprenaline - Very high heart rates


PAH : Nitric oxide: Vasodilator Inhibits - Platelet activation

- SMC proliferation ↓ levels in PAH NO → cGMP

(inactivated by PDE-5, large amounts in lungs)

NO

Advantages

- No ↑ in syst. sat.

- No systemic hypotension - No arterial hypoxemiaDisadvantages - Methaemoglobinemia - Pulmonary edema - Lung injury

NO as Pulmonary vasodilator - Results NO at 40 ppm more effective than 5 ppm

3/15 (20 %) pt with PVR > 8 u fall in PVR < 6 after NO

Response same in those with Down Syndrome

Yasuda T et al,Paediatric Cardiol,2000

NO vs NO + Oxygen combination

Number of responders with combination significantly > than when NO/Oxygen used alone.

Combination of NO + 02 provides add’nal pulmonary vasodilatation & can rapidly identify patients with pulmonary vasoreactivity.

Good postoperative results

Lock et al , JACC 2000

NO + Oxygen combination : PVR 10 u

O2 alone PVR 8 u O2 + NO PVR 6 u

Does not guarantee operability

Wilkinson heart 2001 : 85:113

Lung biopsy Open lung specimen is taken General anaesthesia

Biopsy those with borderline haemodynamics

(Heath. Edwards classification)


PAH

Creating ASD - RVF not relieved R → L shunt - ↓ RA pr. QP ↓, Syst. O2 sat. ↓ CO more stable – syncope relieved. Change in life span - ?


PVOD : Defect occlusion

PDA & some VSDs

Significant fall in PA pressure is helpful in decision making.


PAH Treatment

Prostanoids - Epoprostenol IV E.R.A. - Bosentan PO PDE-5-I - Sildenafil PO CCB - Diltiazem, Amlodip. PO


PAH: Breathe – 5 : ASD & VSDBosentan Vs Placebo – 54 pts., class III, 16 weeks Syst. O2 Sat. maintained. PVR, PAm ↓ Ex. Cap.↑, funct. class ↑ Time to deterioration ↓ Placebo – PVR worsened (?)


PAH : Bosentan : Long FU (12 m – 29 m)

PVR/ SVR ratio ↓ (N- 0.15 to ↓ 0.3) Qp & Qs ↑, R →L shunt ↓ PAp & SAp ↓ (NS) RV after load ↓ more than LV

Initial improvement returns to baseline in 2 years.


PAH : Bosentan

Hepatotoxicity Potentially teratogenic Testicular atrophy & infertility Hormonal birth control - ↓ effectiveness.


PAH : Sildenafil

PAp (m) ↓ 3-5 mms Ex. capacity ↑ Side effects – minor Functional class ↑


PAH : Eisenmenger ASD 40 pts., FU – 4 years, PVR ↑ 7u ASD closed 26, Med. Rx -14

PVR 9-14 - No ↑ in PVR 7-9 - PVR ↓

No vasoreactivity check pre op PVR ↑ in all unopted.

Steele etal Circ. 1987 : 76 : 1037 - 42


PAH : Eisenmenger Pts : O2 ± No 124 Pts, 1 mt 47 yr. (m 28) 74 op or transplant PVR/ SVR – 0.33 or ↑

O2 → Rp/Rs ↓ 0.42O2 + NO Rp/Rs ↓ 0.27

(indicates operable defect)

Balzer etal Circ. 2002 : 106:1-76-81

Operability & Reversibility

Not Synonymous Patients with severe intimal proliferation may

not show decrease in PAP post-op PAH can progress after repair


PVR : mistakes in assessment Presence of A.V. valve regurg. Obligatory shunts Pulm. infection, acidosis, anemia, polycythemia,

hypoxia

SUMMARY Knowledge of determinants of progression of

PVOD is poor

Remember confounding factors affecting PVR in assessing L→R shunts.

Clinical auscultation- fading art.

SUMMARY Age of patient probably THE most important

determinant* Pre tricuspid shunt except TAPVC- Longer

waiting period* Post tricuspid shunt without cyanosis

6 months to 1 year* Post tricuspid shunt with cyanosis

before 3 months

Message

Timely surgical intervention is THE KEY

for good immediate & long term results.

assessment for operability of chd with pah r. tandon

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