Case November 2026 - Suprasystemic Pulmonary Hypertension

Case description 

A term infant (41 weeks corrected, 2 weeks of life) with hypoxic-ischemic encephalopathy, rewarmed after therapeutic hypothermia, was intubated and ventilated (mean airway pressure 15 cmH₂O, FiO₂ 0.33) with pre-ductal saturations around 90%. The infant was receiving multiple anti-seizure medications and was on hydrocortisone and dopamine at 5 mcg/kg/min, the latter started for a suspected low systemic vascular resistance state attributed to the vasodilatory effects of these medications. Blood pressure was 70/52 mmHg and heart rate 90–95 bpm. Weight had risen from a dry weight of 2.8 kg to 4 kg, with anasarca and ascites, in the context of ongoing acute kidney injury with a urine output of 1.25 mL/kg/h and biochemical evidence of renal dysfunction. Lactate was rising. Several contributors were considered: hyperglycemia saturating aerobic pathways and triggering anaerobic metabolism, ongoing seizure activity, and poor renal clearance of lactate and other metabolites; an underlying metabolic condition was also being ruled out. Clinically, despite the anasarca, femoral pulses were good, the capillary refill was around 3 seconds and the infant was warm to the touch. TNE was requested to assess cardiac function in an infant on vasopressors for a suspected phenotype of medication-induced systemic vasodilation, in the setting of this rising lactate.

Targeted neonatal echocardiography showed suprasystemic pulmonary hypertension with right ventricular dysfunction and dilatation. The tricuspid regurgitation jet estimated an RV–RA gradient of 118 mmHg, well above systemic pressure. RV systolic function was moderately depressed by TAPSE and fractional area change, and RV output was reduced, with a PAAT/RVET of 0.19 and rapid acceleration in both branch pulmonary arteries, all pointing to high pulmonary vascular resistance. The ductus arteriosus was extremely small (only seen by colour) and restrictive, shunting right to left with an insignificant volume of desaturated blood entering the descending aorta — not enough to produce a measurable pre-/post-ductal split. The PFO shunted bidirectionally with a significant right-to-left component, but was likewise too small to decompress the right atrium (and to contribute significant deoxygenated blood to the left atrium). All four pulmonary veins were seen entering a subjectively small left atrium, with low pulmonary venous Doppler velocities. There was an A-dominant, low-velocity tricuspid inflow (E 0.21 m/s, A 0.51 m/s), reflecting reduced RV compliance and possibly high RV filling pressures. LV systolic function was preserved by ejection fraction. The IVC and hepatic veins were dilated with ascites, suggesting elevated central venous pressure and impaired venous return as contributors to both the systemic venous congestion and the ascites, alongside the renal dysfunction. 

On the basis of these findings, inhaled nitric oxide was started for pulmonary vasodilation to unload the right ventricle and improve LV preload, dobutamine was added for RV support (epinephrine was deferred because of the hyperglycemia and hyperlactatemia), dopamine was reduced to 2 mcg/kg/min for renal perfusion, hydrocortisone was maintained, and glycemic control (insulin) was considered to limit anaerobic lactate production. The treating team was informed immediately and a follow-up TNE was planned for the afternoon. 

At the follow-up study on iNO 20 ppm, with FiO₂ 0.30, dopamine 2 and dobutamine 2 mcg/kg/min, saturations had risen to 98% with a blood pressure of 67/50 mmHg. The RV–RA gradient had fallen to 26 mmHg (incomplete curve; from 112–119 mmHg), PAAT/RVET had improved to 0.31 (from 0.19), and tricuspid inflow velocities had increased (E 0.35 m/s, A 0.47 m/s), consistent with falling pulmonary vascular resistance and better RV mechanics. TAPSE remained reduced at 0.65 cm but RV-FAC was within normal and the RV appeared less dilated (subjectively). Lactate normalized progressively within 12 hours with an insulin infusion. The clips and still frames below are grouped by echocardiographic window, first from the initial TNE and then from the follow-up study on iNO.

First Targeted Neonatal Echocardiography

TNE report

• Hemodynamics & Pulmonary Pressures: 

  • Severe Pulmonary Hypertension: Findings are consistent with suprasystemic pulmonary hypertension. The tricuspid regurgitation (TR) jet estimates an RV–RA gradient of 118 mmHg. Elevated Pulmonary Vascular Resistance (PVR) suspected: PAAT/RVET indices, combined with rapid acceleration times in both the left and right pulmonary arteries (LPA/RPA), are concerning of bilaterally elevated PVR. 

  • Ventricular Function Right Ventricle (RV): Moderate depression of RV systolic function (evidenced by reduced TAPSE and FAC) with decreased RV output secondary to high afterload. 

  • Left Ventricle (LV): Preserved LV systolic function (normal EF) but mildly reduced LV output (110 mL/kg/min). The LA and LV appear underfilled. This is likely driven by reduced pulmonary blood flow, evidenced by decreased pulmonary venous Doppler velocities. 

  • Shunts 

    • Patent Ductus Arteriosus (PDA): Very small and restrictive, demonstrating right-to-left shunting visible only on color Doppler. The volume of desaturated blood entering the descending aorta is clinically insignificant (insufficient to create a measurable pre-/post-ductal saturation split). 

    • Patent Foramen Ovale (PFO): Bidirectional shunting with a significant duration of right-to-left shunting. However, the defect is too small to adequately decompress the right atrium (RA) or cause systemic pre-ductal desaturation. 

  • Systemic Venous Congestion: 

    • Dilated IVC and hepatic veins with visible ascites. These findings indicate elevated central venous pressure causing systemic venous hypertension and impaired venous return, which likely contributes to the ascites (though renal dysfunction may be a significant compounding factor). 

Conclusion: Severe suprasystemic pulmonary hypertension with moderate right ventricular dysfunction, compromised pulmonary blood flow leading to left heart underfilling, and significant systemic venous congestion. Prostaglandin E1 could be considered to re-open the ductus arteriosus should RV function fail to recover after iNO. At this stage, however, the right ventricle was still able to generate the pressures needed to overcome the high PVR and remained coupled to the pulmonary circulation. Re-opening the duct with PGE1 would possibly create a more significant right-to-left shunt that would lower Qp:Qs. It would offload the RV (at the cost of pulmonary blood flow and systemic oxygenation) and would pressure equalize the PA and the Aorta. PGE1 is also a systemic vasodilator and could worsen systemic hypotension in an infant already exposed to anti-seizure medications with vasodilatory effects of their own. For these reasons, the chosen strategy was to first lower PVR with iNO and support the RV with inotropes, reserving PGE1 as a rescue option.

Suggestions & Plan: We recommended the following medical management strategy: 

• Pulmonary Vasodilation: Initiate iNO to reduce RV afterload, which will subsequently improve pulmonary blood flow and LV preload. 

• Inotropic Support: Initiate dobutamine to support right ventricular function. (Note: Epinephrine was considered a viable alternative but was deferred due to the setting of hyperglycemia and hyperlactatemia). 

• Renal Support: Although evidence regarding this is very limited, dopamine at 2 mcg/kg/min (decreased from 5) to support renal perfusion was opted in this case. Dopamine is of concern regarding a potential effect in increasing PVR. Hence, it was decided to wean the Dopamine. There was no concern at this point of altered SVR due to the vasodilatory effect of anti-seizure medications.  

• Adrenal Support: Maintain hydrocortisone for adrenal support. 

• Metabolic Control: Consider better glycemic control (e.g., insulin) to assist in decreasing lactate levels (8 mmol/L). Glucose was 18 to 20 mmol/L (equivalent to approximately 324 to 360) at the time of the assessment. We suspected that aerobic pathways were overwhelmed by the hyperglycemia, leading to anaerobic spilling that contributes to the rising lactate. 

• Communication: Teamwas immediately notified of these findings and recommendations. 

Follow-up TNE

The repeat TNE was performed three hours after the first study, with iNO at 20 ppm, FiO₂ 0.30, mean airway pressure 15 cmH₂O, pre-ductal saturations of 98% and a blood pressure of 67/50 mmHg, on dopamine 2 mcg/kg/min and dobutamine 2 mcg/kg/min. The response to pulmonary vasodilation was evident across the study. Pulmonary venous Doppler velocities had risen at the left upper and right lower pulmonary veins, and the RVOT Doppler profile had improved, with a PAAT of 58 ms and an RVET of 185 ms (PAAT/RVET 0.31, from 0.19) and a significant increase in right ventricular output. The RV and RA were subjectively less dilated, the tricuspid regurgitation jet was less prominent, and the CW Doppler now estimated an RV–RA gradient of 26 mmHg (2.54 m/s, from 111–119 mmHg), albeit on an incomplete envelope that likely underestimates the true gradient. RV systolic function had improved, with the RV fractional area change normalising to 38% (from 20–25%), although TAPSE remained reduced at 0.65 cm. Tricuspid inflow showed higher velocities (E 0.35 m/s, A 0.47 m/s, from E 0.21 / A 0.51), in keeping with improved RV compliance. On the left side, LA and LV preload had improved, with mitral inflow now E-dominant over two beats (E 0.33 m/s, A 0.31 m/s), LV systolic function was normal, and LV output had normalised to 150 mL/kg/min. The PFO, bidirectional with a predominant right-to-left component on the first study, now shunted left to right throughout the cardiac cycle. The IVC and hepatic veins remained dilated, but hepatic venous Doppler showed systolic forward flow with only brief atrial reversal, which was reassuring regarding right atrial pressure. With these hemodynamic changes and an insulin infusion for glycemic control, lactate normalised progressively over the following 12 hours.

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