PULMONARY HYPERTENSION AC. 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
Congenital Heart Disease Pulm. hypertension : Reversibility Qp on the basis of assumed VO 2 - not reliable 100% : O 2 –VO 2 not known, hence all calculation will be incorrect. Dissolved O2 - (modifies calculations)
Congenital Heart Disease PVOD : O 2 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
CONGENITAL HEART DISEASE 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 hypoxemia Disadvantages - 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 alonePVR 8 u O2 + NOPVR 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)
CONGENITAL HEART DISEASE PAH Creating ASD -RVF not relieved R → L shunt - ↓ RA pr. QP ↓, Syst. O2 sat. ↓ CO more stable – syncope relieved. Change in life span - ?
Congenital Heart Disease PVOD : Defect occlusion PDA & some VSDs Significant fall in PA pressure is helpful in decision making.
CONGENITAL HEART DISEASE PAH: Breathe – 5 : ASD & VSD Bosentan Vs Placebo – 54 pts., class III, 16 weeks Syst. O 2 Sat. maintained. PVR, PAm ↓ Ex. Cap. ↑, funct. class ↑ Time to deterioration ↓ Placebo – PVR worsened (?)
CONGENITAL HEART DISEASE PAH : Bosentan : Long FU (12 m – 29 m) PVR/ SVR ratio ↓ (N to ↓ 0.3) Qp & Q s ↑, R → L shunt ↓ PAp & SAp ↓ (NS) RV after load ↓ more than LV Initial improvement returns to baseline in 2 years.
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.