Balloon Angioplasty for Native Aortic Coarctation in Children and Infants Younger Than 12 Months: Immediate and Medium-Term Follow-Up

Abstract: Background. Despite more than 20 years of experience, balloon angioplasty as treatment for native coarctation of the aorta (CoA) during childhood remains controversial. Methods and Results. Fifty-three pediatric patients with discrete native coarctation for whom balloon angioplasty (BA) was performed were included in this study. Patients were divided into 3 groups: group A patients, ≤3 months of age (n = 20); group B patients, between 4-12 months of age (n = 15); and group C patients, between 1 and 12 years (n = 18). Mean age at BA was 0.9 months for group A, 6.5 months for group B, and 7.8 years for group C. The mean body weight was 4.2 kg for group A, 8.6 kg for group B, and 15.3 kg for group C. Successful BA was achieved in 48 of 53 patients (90.6%). Follow-up revealed re-coarctation in 13/53 patients (24.5%); 6 patients with restenosis were referred for surgery, and 7 underwent a second BA procedure. At the end of the study period, BA was effective in 88.7% of patients. The incidence of peripheral vascular complications following BA was higher in group A (17%). Aneurysms were detected in 3/20 (15%) in group A and 2/15 (13.3%) in group B. Conclusions. BA is a safe and effective treatment for native aortic coarctation. Due to the risk of aneurysm formation in children, cautious selection of patients, the use of low-profile balloons, and state-of-the-art postoperative care are imperative to improve patient outcomes and decrease the risk of complications.

J INVASIVE CARDIOL 2012;24(12):662-666

Key words: balloon angioplasty, coarctation, children

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Balloon angioplasty (BA) for native coarctation of the aorta was first described in 1982,¹ and since then, many studies have reported success for native and recurrent coarctation.^2-9 Despite more than 20 years of experience, BA as treatment for native coarctation of the aorta (CoA) during childhood remains controversial.¹⁰ Moreover, surgical intervention is currently the preferred method of treatment for children in many centers. Many publications have reported a high incidence of restenosis and aneurysm formation for BA in neonates and young infants (<3 months),^11-14 and the coexistence of patent ductus arteriosus (PDA) in a neonate has been linked to restenosis in these patients.^5-7,12 BA has often failed in neonates with long-segment coarctation and isthmic hypoplasia,^15,16 and surgery is the modality of choice for those patients.

Stent implantation has become a common means of treating native and recurrent CoA in adolescents and adults; however, this is not performed routinely in children due to vessel size and the need for repetitive stent dilation to accommodate somatic growth and attain a reasonable adult-sized vessel.

Equivalent relief of obstruction was demonstrated in previous studies comparing surgery and BA, but the risk of aneurysm formation and possible restenosis was higher among patients treated with BA.¹⁰ Despite this apparent difference, the authors of more-recent studies continue to advocate BA for native CoA.^17,18

In this study, we are reporting our experience with BA for native coarctation in infants and young children.

Methods

This is a retrospective study of 53 pediatric patients with discrete native coarctation for whom balloon angioplasty was performed at our institute from January 2002 to December 2010. Patients were divided into 3 groups: group A patients, ≤3 months of age (n = 20); group B patients, between 4-12 months of age (n = 15); and group C patients, between 1 and 12 years (n = 18). Informed consent for balloon dilation was given by the parents. All patients were examined clinically and underwent thorough transthoracic echocardiography (TTE), 12-lead electrocardiogram (ECG), and chest radiography. Blood pressure recordings were taken in both upper and lower limbs and differences were recorded. Supine systolic blood pressure in all 4 extremities was measured with an appropriately-sized cuff on the proximal arm or thigh. The residual resting systolic coarctation gradient was calculated as the difference in systolic BP between the right arm and the lower extremity with the highest measured systolic BP. 

Angioplasty procedure. The catheterization and angioplasty procedures were performed under general anesthesia, using a retrograde femoral arterial approach in all patients; we used a 4 Fr introducer sheath in patients younger than 1 month old, and a 5 Fr sheath for the other patients. The arterial catheter was placed from a retrograde approach, and the pressures of the ascending and descending aorta were obtained. Biplane angiography was performed before and after angioplasty in straight frontal and lateral projections. A 0.035˝, 260 cm, floppy-tip exchange guidewire was placed through an end-hole pigtail catheter positioned above the aortic valve and this was maintained in the ascending aorta throughout the procedure. The balloon catheters were inserted over the wire. Patients were given 50 IU/kg of heparin sulfate intravenously after vascular access was achieved. After conclusion of the procedure, intravenous heparin sulfate was given if the pedal arterial pulse was decreased or absent. If the pulse did not return 6 hours after the procedure, urokinase was administered.

The initial diameter of the balloon for angioplasty was equal to or 1-2 mm greater than the diameter of the aorta at the level of the left subclavian artery and not greater than the diameter of the aorta at the diaphragm. The balloon was inflated under fluoroscopic guidance 2-3 times for each patient. The pressure of balloon inflation did not exceed that stated by the manufacturer. If a residual waist was evident at the coarctation site, the next largest balloon diameter was chosen for dilating the coarctation within the above guidelines.

Catheterization and angioplasty data. The peak-to-peak systolic pressure gradient across the coarctation site was measured before and after angioplasty procedures. The diameters of the coarctation site were recorded. Most measurements were obtained from the systolic frames and lateral projections (Figure 1). 

Statistical methods. The data are expressed as mean ± standard deviation. The pre- and postdilation mean values of the peak-to-peak systolic ascending to descending aorta pressure gradient and diameter of coarctation were tested with paired t-test. Analysis of success and recurrence rate between groups A and B was undertaken using Fisher’s exact test.

Patients were followed after 1, 2, and 4 weeks (short-term follow-up), and at 6, 12, and 18 months (medium-term follow-up. This included sphygmomanometric blood pressure measurements of the upper and lower limbs, as well as full TTE including 2-dimensional and Doppler studies. If the patient had a pressure gradient of more than 20 mm Hg by sphygmomanometry or by Doppler ultrasound, then repeat angioplasty was considered; in the case of aneurysm development, either surgery or conservative follow-up was advocated.

Results

From January 2002 to December 2010, fifty-three pediatric patients with discrete native coarctation for whom BA was performed were included in this study. Patients were divided into 3 groups: group A patients, ≤3 months of age (n = 20); group B patients, between 4-12 months of age (n = 15); and group C patients, between 1 and 12 years (n = 18). Mean age at BA was 0.9 ± 0.4 months for group A (range, 0.6-3 months), 6.5 ± 2.1 months for group B (range, 5.2-10.7 months), and 7.8 ± 2.9 years for group C (range, 6.3-11.4 years). The mean body weight was 4.2 ± 1.6 kg for group A, 8.6 ± 2.2 kg for group B, and 15.3 ± 6.7 kg for group C (Table 1).

Forty-one out of 53 patients (77.4%) presented with heart failure, and Doppler echocardiography for those patients revealed significant coarctation. By sphygmomanometry, all patients had a high resting RT arm systolic blood pressure and a high resting systolic gradient greater than 20 mm Hg between the upper and lower limbs.

Left heart dimensions, systolic function, and the grade of secondary mitral valve regurgitation were examined by comprehensive TTE examination. 

All groups demonstrated marked left ventricular hypertrophy, significant left ventricular dilatation and borderline or impaired systolic systolic function. Values are illustrated in Table 2.                  

Secondary mitral valve regurgitation (MR) was documented in 37/54 cases (68%): grade I MR in 13/37 cases (35%) and grade II MR in 24/37 cases (65%).

Balloon angioplasty results. The balloon angioplasty results are shown in Table 3. The mean value of the peak-to-peak systolic ascending to descending aorta pressure gradient significantly decreased from 64.5 ± 3.1 mm Hg to 12.6 ± 1.7 mm Hg in group A (P<.05), from 58.9 ± 2.3 mm Hg to 8.9 ± 2.9 mm Hg in group B (P<.05), and from 61.7 ± 4.8 mm Hg to 11.7 ± 4.1 mm Hg in group C (P<.05) after balloon dilation. The mean diameter of coarctation significantly increased from 3.1 ± 1.1 mm to 6.8 ± 1.3 mm in group A, from 3.9 ± 1.6 mm to 8.2 ± 2.4 mm in group B, and from 4.6 ± 2.7 mm to 9.4 ± 3.1 mm in group C (P<.05) after balloon dilation.

Success rate. Balloon dilation was considered successful if the peak systolic pressure gradient across the coarctation site was less than 20 mm Hg and the coarcted segment increased in diameter by more than 50%.¹² Initial results after BA were successful in 48 of 53 patients (90.6%) with a peak residual pressure gradient <20 mm Hg. Success was achieved in 17 of 20 patients in group A (85%), in 13 of 15 patients in group B (87%), and in 17 of 18 patients in group C (94.4%). There was no significant difference between groups A and B in the success rate (P>.05). The mean peak-to-peak pressure gradient dropped from 56.9 ± 20.3 mm Hg to 12.4 ± 6.1 mm Hg (P<.001) and the maximal coarctation diameter increased from 3.7 ± 1.9 mm to 7.4 ± 1.6 mm after BA in the whole study group. As regards the balloon diameter and the mean procedure time, there were no significant differences between the 3 groups. There was a significant reduction in the right arm systolic BP and significant gradient reduction between right arm and leg in all groups post BA (P<.05^*). However, on comparing the 3 groups, there were no statistically significant differences in the degree of reduction of either right arm SBP or the gradient reduction between right arm and leg (P>.05). 

Short-term follow-up after 1, 2, and 4 weeks, and medium-term follow-up at 6, 12, and 18 months revealed re-coarctation in 13/53 patients (24.5%), with 7/20 of them in group A (35%), 3/15 in group B (20%), and 3/18 in group C (5.7%). Six patients with re-coarctation were referred for surgery (5 in group A and 1 in group B) and 7 underwent a second BA procedure (2 in group A, 2 in group B, and 3 in group C). At the end of the study period, BA was effective in 47/53 of patients (88.7%). The incidence of peripheral vascular complications following BA was higher in group A (17%) than for group B (8.5%) and C (6.2%). Aneurysms were detected in 8% of the entire study group, with 3/20 (15%) in group A, 2/15 (13.3%) in group B, and 0 in group C (P<.05^*).

Procedural complications. One case of mortality due to fulminant bronchopneumonia in the 6th postoperative day, unrelated to the procedure, occurred in group A. One case out of 20 in group A developed moderate hemopericardium (6-week-old male child, 3.7 kg with discrete ring coarctation; coarcted diameter 3.7 mm, gradient of 53 mm Hg, balloon used was 8 x 2 mm). He was successfully managed by 3 Fr pigtail cannulation of the pericardium and re-injecting the blood an average of 30 cc over a duration of 34 minutes until it stopped spontaneously and was hemodynamically stable 36 hours after the procedure. The incidence of peripheral vascular complications following BA was higher in group A (3/20; 15%)than for group B (1/15; 7%) or group C (1/18; 6%; P<.05^*). These were in the form of loin hematoma, iliofemoral spasm, and thrombosis in 1 case, which was successfully managed using heparin and urokinase.

Follow-up data. Doppler assessment of the patency of the femoral vessels was routinely done 6 hours, 24 hours, and 1 week after the procedure. 

Right and left lower limb lengths were measured from the anterior superior iliac crest to the plantar surface of the heel before the procedure and were followed monthly to the endpoint of the study. No patients suffered any limb-length discrepancies.

Aneurysms were detected by TTE in 3/20 (15%) in group A and 2/15 (13.3%) in group B. Magnetic resonance angiography (MRI) was performed for these patients to document the size and shape of the aneurysms, as well as 6-month follow-up MRIs to monitor the progression of these aneurysms. 

The study group will also receive yearly MRI evaluations starting at 2 years post dilatation to record the long-term results of the technique.

Discussion

The report of BA in the treatment of native CoA in an infant with congestive heart failure in 1983¹⁸ initiated a controversy that persists today. Acute and 1-year follow-up results of a prospective comparison of BA and surgery for native CoA showed a similar immediate gradient reduction, but a higher risk of aneurysm formation and possibly restenosis with BA among 36 patients age 3 to 10 years.¹ 

BA of native coarctation appears to be gaining more acceptance in children.¹⁹ In neonates and young infants, the reported higher incidence of restenosis and aneurysm formation perpetuates the controversy. For this reason, we are reporting our experience and outcomes of BA among this group of 53 infants and children.

In this study, the immediate success rate in group A was 90.6%, which is concordant with other series where the early success rate in infants age 3 months or younger has ranged from 88% to 100%.^2-7,11,12 On comparing the three groups, success rate was 90.6% for group A, 87% for group B, and 94.4% for group C; initially, BA had a good result in all groups and no statistically significant differences between the three groups were observed (P>.05). The results of this study are comparable to those reported by other groups regarding the initial efficacy of the technique, incidence of re-coarctation, and appearance of aneurysms.^15,16,20

The restenosis rate in infants age 3 months and younger reportedly ranges from 50% to 71%.^2-7,12 In most cases (71%-80%), except for a few patients needing operation, the restenosis could be treated by balloon angioplasty and the success rate was 80%-100%.^8,9 In this study, 13/53 cases (2.5%) developed stenosis, which is a lower rate than evidenced in other series. Seven out of 20 patients (35%) in group A, 3/15 patients (20%) in group B, and 3/18 patients (5.7%) in group C developed restenosis, The mean time to development of restenosis was 8.8 weeks for group A, 19 weeks for group B, and 30.75 weeks for group C, and 7/13 patients (54%) with restenosis underwent successful repeat BA. When comparing groups A, B, and C, the restenosis rate was higher in groups A and B (35% and 20%, respectively) than group C, and this difference was significant (P<0.05). The greater incidence of re-coarctation found in patients younger than 1 year old matches reports from other series.^6,7,18

Both immediate and late aneurysm formation have been reported and the incidence of aneurysm at the dilation site ranges from 0% to 5%.^3,4,12,21 We defined an aneurysm as an out-pouching of the aorta, not present before angioplasty, which increased the nominal diameter of the aorta by up to 20%.³ In the present study, 5/53 patients (9%) developed aneurysmal malformations (3/20 in group A [15%] and 2/15 patients in group B [13%]). 

The potential development of aneurysms has long been considered a major limitation to BA. A strikingly higher incidence of aneurysm formation after BA (35% versus 0% for surgery) was seen in a study by Cowley et al in 2005,⁸ with the development of 3 aneurysms more than 5 years after the initial intervention. The 35% incidence of aneurysm formation among BA patients in that series is similar to some early reports in which aneurysm formation occurred in 36%-43% of children treated with BA.^10,11 More recently, Walhout et al²² found no aneurysms among 32 children with native CoA treated with BA, but the duration of follow-up was shorter.  

In the present work, the mean time to development of aneurysms was 10.3 months and 7.9 months for groups A and B, respectively. Aneurysms were discrete and small in size, and were considered acceptable. At the end of 18 months of follow-up, the aneurysms were stationary with no evidence of progress and were followed conservatively. No relation was found between their appearance and the balloon-diaphragmatic aorta ratio or balloon/stenosis ratio. Factors dependent on the patient and the lesion itself (presence and extension of the cystic medial necrosis)⁸ may also influence the development of postangioplasty aneurysms. The later development of aneurysms in our series as well as other studies demonstrates the importance of long-term imaging in patients who have undergone BA.

Conclusion

From the results of this study, we conclude that BA is a safe and effective treatment for native aortic coarctation, even during the neonatal period. However, due to the higher risk of aneurysm formation in children versus in infants, cautious selection of patients, the use of low-profile balloons, and state-of-the-art postoperative care are imperative to improve the outcomes and decrease the risk of complications. Moreover, it is clear that aneurysms can develop early or late, which necessarily mandates long-term close follow-up of patients treated with BA. 

References

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From the Department of Pediatrics, Faculty of Medicine, Cairo University, Cairo, Egypt.

Disclosure: The author has completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. The author reports no conflicts of interest regarding the content herein.

Manuscript submitted April 30, 2012, provisional acceptance given June 6, 2012, final version accepted June 25, 2012.

Address for correspondence: Prof. Rasha I. Ammar, MD, Department of Pediatrics, Faculty of Medicine Cairo University, Pediatrics, Cairo, Egypt. Email: rashaammar@gmail.com