DR SP MACHAWIRA
University of Wits
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Pulmonary hypertension complicates 2% of
patients undergoing congenital cardiac
surgery(Adatia I et al 2009)
In India 60% of post operative deaths due to PHT
crises(Choudhary SK et al Ann Thorac Surg 1999)
The functional and structural status of the
pulmonary bed important
Immediate post-operative period the most
vulnerable time
Pulmonary endothelium dysfunction the most
important factor but pathophysiology
incompletely understood
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The outcome of patients has improved due to
better understanding of peri-operative
management
PHT is an independent risk factor in morbidity
and mortality in patients undergoing
congenital cardiac surgery
Pulmonary hypertensive crisis is the extreme
end and a feared complication associated with
increased morbidity and mortality
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Complicates 0.75% of congenital cardiac surgery
and has a mortality of 20%
Pathophysiology incompletely understood and
complex
Increased post operative vasoreactivity to
sympathetic stimuli
Vasospastic stimuli result in sudden increase of
pulmonary artery pressure and resistance
Right heart failure with TR
Systemic hypotension and MI
Increased airway resistance
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Complex and unpredictable
Prevention is the best
Identifying patients at risk
Pre-operative care
Intra-operative care
Post-operative care
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Early surgery prevents the development of
pulmonary vascular obstructive disease
Sedation with fentanyl and paralysis first 24
hours
Prevent acidosis: pH and not pCO2 increases
pulmonary vascular resistance
Correct hypothermia
Maintain adequate oxygenation but avoid baro
and volutrauma
Correct polycythaemia to reduce PVR
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Difficult to predict influenced by age, lesion &
pre-existing endothelial cell dysfuction
Usually affects patients with reactive
pulmonary vascular beds
Patients with pulmonary venous
hypertension(TAPVC) have extremely reactive
beds
Extra-cardiac syndromes eg Trisomy 21,
omphalocele
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PA arising from the aorta, Truncus arteriosus,
AP window
Single ventricle physiology with unrestricted
pulmonary blood flow
mPAP >25mmHg or 50-60% of systemic on
coming off bypass with signs of low cardiac
output
Patients with residual lesions
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Severe CCF needs significant resuscitation
Intubation and ventilation may be necessary
to correct metabolic derangements
Control and treat sepsis
Avoid hypotension at induction may cause
cardiac ischaemia
Need to maintain Qp:Qs at 1:1 to ensure
adequate organ perfusion as pulmonary
overcirculation implies systemic
hypoperfusion
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Hypercapnia and low FiO2 increase PVR to
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Smaller tidal volumes once sternum open
Cardiopulmonary bypass, hypothermia and
circulatory arrest enhances pulmonary vasoreactivity
Complete repair where possible
PFO may be a life saving procedure allowing
for pop-off valve
Use of PAP lines debatable increased risk of
bleeding, overreacting to changes, considered
mandatory in research on new drugs
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ICU care plays a critical role in the patient outcome
Anticipate and treat PHT crises aggressively
Sedation with Fentanyl and paralysis in the first 24
hours especially when suctioning to avoid pain
and anxiety
Adequate oxygenation without barotrauma or
hyperoxygenation
Avoid hypercapnia however pH control more
important
pH> 7.4 or pH>7.5 when patient has had a crisis:
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HCO3 and hyperventilation may be necessary
Effect of pH and CO2 on PVR
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Use of inodilators eg milrinone, dobutamine,
low dose adrenaline with nitroglycerin
Specific pulmonary vasodilators iNO,
prostacyclin, sildenafil
Investigate surgical accuracy ie residual lesions
ECMO
RVAD
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Nitric oxide produced by endothelial cell final
pathway to vasodilation
Accepted mode of treatment for post-operative
pulmonary hypertension
Easy to administer, minimal side effects and
specific for pulmonary vascular bed
Dose 2-80ppm, however no clinical benefits of
doses>10-20ppm
Rebound PHT wean slowly from 5ppm at
0.5ppm/2hours- prolongs ventilation
Side effect methaemoglobinaemia(>5%) negligible
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Type 5 phosphodiesterase inhibitor
Can be used to assist with weaning off iNO
hence earlier extubation
At doses of 0.3-0.5mg/kg/6hourly can be used
to prevent rebound PHT on weaning iNO
Can be used in conjuction with iNO, and
inhaled Illoprost in patients who are in
refractory PHT
May be useful in transition to chronic therapy
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Prostacyclin analogue, inhibits thrombocyte
aggregation and brings about vasodilation
Can be inhaled or intravenous
Inhaled has half life 30 minutes
No toxic effects
Effect comparable to iNO
Can be used in PHT resistant iNO
Can be used intermittently thus allows for
weaning off from ventilation
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ECMO used much less often due to general
improvement in peri-operative care
RVAD
Prophylactic therapy citrulline, sildenafil and
endothelin receptor inhibitors
Combination therapy in refractory cases