The Other Organ in the Chest: How a Baby's Heart Responds to Diaphragmatic Hernia Surgery

Three 2026 ultrasound studies explain what happens to the heart before and after repair, and what that means for families in the NICU

When a baby is born with a hole in the diaphragm, the heart is squeezed as well as the lungs. Three studies published in 2026 used bedside ultrasound to follow how the heart works before and after the operation that closes the gap. Together they show that the right side of the heart recovers quickly after surgery, while the left side may briefly struggle — and that both can be measured, anticipated, and managed.

What congenital diaphragmatic hernia is, and why the heart is involved

The diaphragm is the sheet of muscle that separates the chest from the abdomen. In about one in every 4,000 to 5,000 babies, it does not close completely during pregnancy [1]. Through that gap, organs that belong in the abdomen — usually bowel, sometimes the liver — move up into the chest. This is called congenital diaphragmatic hernia, and the term simply means a hernia through the diaphragm that was present from birth.

The lung on the affected side has less room to grow, so it is smaller than it should be. That is the part of the condition most families hear about first. But the same crowding pushes the heart across the chest and presses on it, and the blood vessels of the underdeveloped lung are stiff and narrow. After birth, when the baby must send all their blood through those lungs, the right side of the heart has to pump against high resistance. The left side, which has been squashed and underfilled since before birth, is often small and works less strongly than it should. Doctors call the high pressure in the lung blood vessels pulmonary hypertension, and it is one of the main reasons these babies need intensive care.

How care for these babies has changed

For decades, the focus was almost entirely on the lungs. Babies were often taken to surgery quickly, on the assumption that removing the pressure would let the lung expand. Over time it became clear that the immediate problem after birth was not the hernia itself but the circulation, and practice shifted to stabilising the baby first — using gentle ventilator settings that avoid injuring the fragile lung, and operating only once the baby's breathing and blood pressure have settled. European neonatal units agreed a shared set of standards for this approach, covering oxygen targets, ventilator limits, and readiness for surgery [2].

Then a further shift happened. Researchers looking at large groups of babies found that how well the heart muscle was pumping predicted survival better than the size of the hole in the diaphragm did [3]. The heart, in other words, was not a bystander. What was still missing was the detail: which heart measurements matter most, and at what moment they should be taken. That is the gap the 2026 studies set out to fill.

What the three studies did

All three used echocardiography — an ultrasound scan of the heart, performed at the cot side, that is painless and involves no radiation. In modern neonatal units this is done by clinicians with specific training in heart ultrasound for newborns, following an agreed protocol [4].

The first study, by Ting and colleagues, followed 44 babies at four hospitals — in Vancouver and Calgary in Canada, Melbourne in Australia, and Iowa in the United States — scanning them before the operation, in the days just after, and again at about two weeks of age [5]. The second, by Ali and colleagues, compared scans taken within 24 hours before surgery and 24 to 48 hours afterwards in 52 babies at hospitals in Riyadh, Saudi Arabia, and London, United Kingdom [6]. The third, by Shalaby and Taha, followed 30 babies at a university hospital in Tanta, Egypt, scanning them before surgery, two to three days afterwards, and again a month later [7].

What they found before the operation

In the four-hospital study, 18 of the 44 babies (about four in ten) either died or still needed a breathing tube beyond two weeks of age. What separated them from the others was not how early they were born or how much they weighed — those were similar in both groups. It was two things visible before surgery: whether the liver had moved up into the chest, and how much blood the heart was pumping [5].

Babies who went on to have a harder course were pumping noticeably less blood from both sides of the heart, and their heart muscle was moving more sluggishly on the scan. The numbers were not subtle. Among babies whose liver was in the chest, a low pumping volume before surgery separated the two groups almost perfectly. This does not mean a single scan can predict any individual baby's future — these are small groups of babies and the findings need to be confirmed in larger studies — but it does mean that a scan before the operation gives the team real information about the road ahead, which they can share honestly with parents.

That prognostic use of ultrasound has a history. An earlier study found that babies whose lung blood pressure was still high in the second week of life did worse than those whose pressure came down [8], and other work showed that a small, weakly pumping left side of the heart changes which medicines are safe to use, because drugs that open up the lung blood vessels can overwhelm a left ventricle that is not ready to handle the extra blood returning to it [9].

What happens in the days after surgery

Once the hernia is repaired and the abdominal organs are returned to where they belong, the pressure on the heart and lung is relieved. Two of the studies measured exactly what that relief looks like.

In the Riyadh and London study, almost everything improved within a day or two [6]. The right side of the heart, which had been working hardest, moved much better. The wall between the two pumping chambers, which had been pushed out of shape by high pressure on the right, returned to its normal position in most babies. Abnormal blood flow patterns settled. And the medicines came down sharply: the proportion of babies needing inhaled nitric oxide, a gas used to open up the lung blood vessels, fell from roughly four in five before surgery to about one in seven afterwards.

In the Egypt study, which scanned babies slightly later — two to three days after surgery rather than one to two — the right side improved in exactly the same way, and the left side of the heart visibly grew now that it was no longer compressed [7]. But the left side's pumping strength dipped temporarily. It had fully recovered, and was in fact stronger than before, by the one-month scan. Babies whose pumping dipped most were the ones who needed more blood-pressure support in those first days.

Taken together, this is a reassuring picture with a practical caveat. Surgery does relieve the strain, and the improvement is fast. But the left side of the heart, which spent months squashed and underused before birth, suddenly receives much more blood to handle, and it can take a few days to adjust. Because the two studies scanned at different times and included babies of different severity, the difference between them is more likely a matter of timing than a genuine disagreement.

What this means for families

If your baby has this condition, you can expect heart ultrasound scans to be part of routine care, before and after the operation. It is reasonable to ask the team what the scans showed and how they compare with the previous one — the change between scans is often what matters most, more than any single number. It is also worth knowing that a temporary dip in heart function in the first days after surgery is a recognised, usually short-lived pattern rather than a sign that the operation went badly. Blood pressure medicines given during that window are supporting a heart that is adapting, not failing.

Doctors also increasingly recognise that a small or weakly pumping left side of the heart is one of the most important warning signs in this condition [10], which is why the team may focus on it even when your baby's breathing seems to be the obvious problem.

What researchers are working on next

Several questions remain open. The thresholds identified in these studies need testing in larger groups before they can guide decisions about when to operate. Researchers are also developing an approach that tailors treatment to which part of the circulation is most affected — the lung blood vessels, the right side of the heart, or the left — rather than treating all high lung pressure the same way [11]. And there is interest in whether treatment before birth changes any of this. A randomised trial of a procedure called fetoscopic endoluminal tracheal occlusion (FETO), in which a small balloon is placed in the baby's windpipe during pregnancy to encourage lung growth, was carried out at centres experienced in FETO and other forms of surgery before birth; it improved survival to hospital discharge from 14% to 36% in the most severely affected babies, but did not report what happened to the heart around the time of repair [12].

None of these studies answers every question, and all three followed relatively small numbers of babies. What they add up to is a clearer, more honest map of a difficult few days — one that lets teams anticipate problems instead of reacting to them, and lets families know what to expect [13]. Longer-term outcomes after repair, including development, are covered separately in our cluster on neurodevelopmental risk after congenital diaphragmatic hernia repair.

References

  1. Paoletti M, Raffler G, Gaffi MS, Antounians L, Lauriti G, Zani A. Prevalence and risk factors for congenital diaphragmatic hernia: a global view. J Pediatr Surg. 2020;55(11):2297–2307. doi:10.1016/j.jpedsurg.2020.06.022 ↩
  2. Snoek KG, Reiss IKM, Greenough A, Capolupo I, Urlesberger B, Wessel L, et al. Standardized postnatal management of infants with congenital diaphragmatic hernia in Europe: the CDH EURO Consortium Consensus — 2015 update. Neonatology. 2016;110(1):66–74. doi:10.1159/000444210 ↩
  3. Patel N, Lally PA, Kipfmueller F, Massolo AC, Luco M, Van Meurs KP, et al. Ventricular dysfunction is a critical determinant of mortality in congenital diaphragmatic hernia. Am J Respir Crit Care Med. 2019;200(12):1522–1530. doi:10.1164/rccm.201904-0731OC ↩
  4. McNamara PJ, Jain A, El-Khuffash A, Giesinger R, Weisz D, Freud L, et al. Guidelines and recommendations for targeted neonatal echocardiography and cardiac point-of-care ultrasound in the neonatal intensive care unit: an update from the American Society of Echocardiography. J Am Soc Echocardiogr. 2024;37(2):171–215. doi:10.1016/j.echo.2023.11.016 ↩
  5. Ting JY, Sehgal A, Kuan MTY, Soraisham A, Vorhies E, Castaldo M, et al. Echocardiographic predictors of adverse outcomes in infants with congenital diaphragmatic hernia. J Perinatol. 2026;46(6):1020–1026. doi:10.1038/s41372-026-02670-5 ↩
  6. Ali K, Nandunjappa M, Homedi A, Arattu Thodika FMS, Subba-Rao R, Almahdi M, et al. Early post-operative hemodynamic recovery in infants with congenital diaphragmatic hernia. Eur J Pediatr. 2026;185(5):281. doi:10.1007/s00431-026-06907-5 ↩
  7. Shalaby MM, Taha FA. Cardiac performance and left ventricular dimensions in neonates with left-sided congenital diaphragmatic hernia before and after surgical repair. J Cardiothorac Surg. 2026;21(1):446. doi:10.1186/s13019-026-04289-1 ↩
  8. Lusk LA, Wai KC, Moon-Grady AJ, Steurer MA, Keller RL. Persistence of pulmonary hypertension by echocardiography predicts short-term outcomes in congenital diaphragmatic hernia. J Pediatr. 2015;166(2):251–256.e1. doi:10.1016/j.jpeds.2014.10.024 ↩
  9. Kinsella JP, Steinhorn RH, Mullen MP, Hopper RK, Keller RL, Ivy DD, et al. The left ventricle in congenital diaphragmatic hernia: implications for the management of pulmonary hypertension. J Pediatr. 2018;197:17–22. doi:10.1016/j.jpeds.2018.02.040 ↩
  10. Fraga MV, Hedrick HL, Rintoul NE, Wang Y, Ash D, Flohr SJ, et al. Congenital diaphragmatic hernia patients with left heart hypoplasia and left ventricular dysfunction have highest odds of mortality. J Pediatr. 2024;271:114061. doi:10.1016/j.jpeds.2024.114061 ↩
  11. Byrd CE, Wren JT, Desiraju S, McNamara PJ. A hemodynamic-driven approach to chronic pulmonary hypertension in congenital diaphragmatic hernia. J Perinatol. 2026;46(6):1100–1108. doi:10.1038/s41372-026-02582-4 ↩
  12. Deprest JA, Nicolaides KH, Benachi A, Gratacos E, Ryan G, Persico N, et al. Randomized trial of fetal surgery for severe left diaphragmatic hernia. N Engl J Med. 2021;385(2):107–118. doi:10.1056/NEJMoa2027030 ↩
  13. Patel N, Massolo AC, Kraemer US, Kipfmueller F. The heart in congenital diaphragmatic hernia: knowns, unknowns, and future priorities. Front Pediatr. 2022;10:890422. doi:10.3389/fped.2022.890422 ↩