This study aimed to evaluate the effect of coarctation of aorta anatomy and balloon profile on the outcome of balloon angioplasty in infantile coarctation.
Recoarctation was lower in infants with discrete coarctation anatomy without arch or isthmus hypoplasia. Therefore balloon angioplasty may be an excellent choice for this patients’ group.
In this study, immediate results after balloon angioplasty showed a significant decrease in COA gradient after high pressure and low-pressure balloons, but high-pressure balloons showed more decrease in coarctation gradient.
Management of COA is indicated when the gradient during cardiac catheterization is more than 20 mmHg [5, 16]. In the present study, all the infants had a peak gradient of more than 20 mm Hg. That gradient decreased to below 20 mmHg just after balloon angioplasty. In a study by Oswal et al. (n = 44 infants), the mean gradient was decreased from 48.05 ± 15.26 mm Hg to 10.97 ± 5.8 mm Hg and showed a successful immediate result after the balloon angioplasty of COA [17]. Reduction in peak-to-peak pressure gradients across the COA, a significant increase in COA diameter by angiography, improved heart failure, and decreased hypertension following balloon angioplasty of COA reported in some studies [18,19,20,21,22,23,24].
In this study, 21% of infants needed reintervention. Other studies have reported a reintervention rate between 6 to 53% for recoarctation of the aorta. There was no statistically significant difference between the patients who need reintervention and others in the age of first balloon angioplasty, the stenotic part's diameter, pressure gradient before the first balloon, and pressure gradient after first balloon angioplasty. Also, other studies showed no difference between the two groups. The recoarctation rates were related to age at angioplasty than to the route, which the procedure was performed, and recoarctation was more in the neonate (< 30 days) [25].
In our study, the pressure gradient of COA decreased more in the high-pressure balloon group, and the rate of recoarctation was significantly lower in this group. For balloon angioplasty of COA, low profile balloons like Tyshak II balloons, which may be introduced through 4-French sheaths or Mini-Tyshack and can be entered via 3-French sheaths should be used. But a new high-pressure balloon for peripheral angioplasty has a low profile and can be entered via 5-Frech sheaths that can be used in infants [19].
Similar studies in all age groups reported the effect of balloon angioplasty immediately after the procedure. A low-pressure balloon is recommended for infants with a small body, particularly in cases with native CoA. In recoarctation cases, the site of aortic tissue usually undergoes some degree of fibrosis. Thus, a low-pressure balloon may result in inconsistent results. However, the infant is usually provided with sufficient time to grow for stenting at an elder age [7]. In the present study, it was observed that the angioplasty balloon-type had no effects on ascending and descending aortic systolic pressure gradients in infants with native CoA, and the immediate results were similar after angioplasty with both types. Despite this finding, there was a difference between the two balloon types in terms of recoarctation, aneurysm, and mortality remains unclear.
In another study by our team, the rate of recoarctation was reported at four percent in children > 1 year of age [26], which is less than that the result of the present study (21.4%) and a rate of 7–30% reported [27]. Regarding the higher incidence of recoarctation in neonates than in elderly patients following balloon angioplasty, it may be explained that despite the rapid control of rupture and elongation in the intima and media with the balloon, the residual abnormal ductal tissue results in elastic recoil at the coarctation site. Besides, smooth muscle proliferation induces intimal hyperplasia, and the above two cases predispose the patient to recoarctation [28]. Some evidence by Atalay et al. presented that histologic findings such as neointimal proliferation, aortic intimal fibrosis in the arterial root, and ductal residual tissue debris together with a high-pressure gradient before balloon angioplasty can lead to an increased chance of recoarctation [29].
In this study, all age groups had similar immediate responses to decreased gradient, but age groups of < 1 month had more recoarctation than 1–3 months and 3–12 months. Similarly, Sen et al. reported that their studied parameters had no effects on recoarctation, and only the presence of residual coarctation in pre-discharge echocardiography was an independent predicting parameter [28].
In this study, the post-balloon angioplasty aneurysm rate was 7.2%, which varies widely (5–43%) in different studies. This discrepancy can be related to technical differences, duration of the follow-up period, lack of systematic imaging during follow-up in many studies, and differences in the aneurysm detection criteria [30, 31]. It is noteworthy that the extent and mechanism of aneurysm formation in CoA may also be explained by elastic fibers' rupture [32]. One aneurysm formation was in the low-pressure group and two of them were in the high-pressure group. Besides, all aneurysm formation was in group 2 of arch anatomy with hypoplastic isthmus that can be explained by dog bone shape formation during balloon angioplasty in this patients’ group.
It is still challenging to select the surgical technique or balloon angioplasty because most previous studies were retrospective and single-centered and evaluated the method that selected by health centers and surgeons. In most studies, there is a short follow-up period for the patients and limited data on mortality rates, and both methods are associated with the possibility of aortic rupture, aneurysm, recoarctation, other complications, and even death [13]. However, the evidence suggests several benefits for balloon angioplasty compared to surgery in neonates, especially those aged less than three months, and there is a considerable mortality rate in neonatal surgical technique. Furthermore, surgery is very challenging in recoarctation and it is associated with high morbidity and mortality, particularly in neonates, compared to native CoA surgery [8, 9], with a reported mortality rate of 0.7% [32]. One of the disadvantage of balloon angioplasty is higher risk of recoarctation compared to surgery; however, angioplasty or stenting is the choice technique, and surgery is avoided in the cases with recoarctation. Although the rate of the aneurysm is relatively higher in balloon angioplasty, most patients undergo follow-up and conservative treatment and do not experience surgery [29]. Overall, balloon angioplasty outcomes seem to be close to surgical results in infants < 3 months of age in terms of treatment options, but with fewer complications, shorter intubation duration, and more extended hospital stay [33]. Therefore, balloon angioplasty is effective in neonates and has advantages over surgery. However, selective treatment depends on the patient's age and clinical status, the stenosis's anatomy, and its adjacent structures [11, 34].
The present study suffers from some limitations, and small sample size to evaluate all related complications, and a lack of long-term follow-up.