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Severe Aortic Coarctation in Infants Less Than 3 Months: Successful Palliation by Balloon Angioplasty
April 2003
Key words: aortic coarctation, balloon angioplasty, infants, neonates, transcatheter management
Treatment of native aortic coarctation (AC) by balloon angioplasty (BA) is a controversial issue,1–6 but gradually the procedure is gaining acceptance in the management of children7–12 with native coarctation. However, it remains controversial in neonates and young infants.2,13,14 Because of the excellent results that we have been able to achieve with BA in neonatal and infant coarctations,13,15–19 we have utilized this technique as a first-line therapeutic option to treat native coarctation in this subset of patients. In addition, we utilize transumbilical arterial18,20 and anterograde21 approaches whenever possible to avoid femoral artery injury. We have reviewed our experience with BA of native coarctation in neonates and infants Inclusion/exclusion criteria. All symptomatic (congestive heart failure, hypertension or both) infants Balloon angioplasty technique. The BA technique that we have used has been described in detail in our prior publications.13,15,18,22–24 Here we reiterate some important technical aspects. 1) Balloon size: the diameter of the balloon selected for balloon dilatation was >= 2 times the size of the coarcted segment, but no larger than the diameter of the descending aorta at the level of the diaphragm. We initially select a balloon size equal to an average of the diameter of the isthmus or transverse aortic arch and descending aorta at the level of the diaphragm. If there was inadequate relief of obstruction (pressure gradient and angiographic improvement), a balloon as large as the descending aorta at the level of the diaphragm was used.22 2) Balloon inflation: the pressure of balloon inflation was monitored and was not allowed to exceed balloon burst pressure as stated by the manufacturer, thus preventing inadvertent balloon rupture. 3) Heparin: heparin, 100 units/kg, was administered before introducing the balloon catheter and activated clotting times were monitored and kept between 200–250 seconds. 4) Balloon catheters: in UA cases, we initially used Proflex-5 catheters (Peripheral Systems Group, Mountain View, California);18 subsequently, we used Ultrathin and Diamond (Meditech, Watertown, Massachusetts) and most recently Tyshak-II catheters (Braun, Bethlehem, Pennsylvania). In FA and FVA cases, Ultrathin and Diamond catheters were initially used followed later by Tyshak-II catheters; the latter were introduced via 4 French (Fr) sheaths. In the last 2 cases of the FA group, Mini-Tyshak catheters introduced via 3 Fr sheaths were utilized. 5) Post-dilatation catheter manipulation: tips of the guidewires or catheters were not manipulated over the freshly dilated coarctation segment to avoid aortic perforation.25Data collection. The data acquired and analyzed were detailed in our previous publications24,26 and will not be reviewed. Information collected included the timing and type of reintervention following angioplasty.
Statistical analysis. Data are expressed as means ± standard deviations for normally distributed variables. Medians and ranges are given for data that are not normally distributed. Comparisons of data prior to and following intervention were made by 2-tailed t-tests, while comparisons between groups were made by analysis of variance. Comparisons of data that were not normally distributed were made by appropriate non-parametric analogues.
Categorical values were compared by Chi-square or Fisher exact tests. A p-value Study subjects. Fifty-one neonates and infants less than 3 months old underwent BA of native AC during a 6.5-year period ending June 2001. They were 1–90 days in age (mean age, 36–34 days). Twenty-six were neonates (18 Five infants presented with severe left ventricular dysfunction, the so-called “hypertensive cardiomyopathy”, similar to a case that we previously reported.17 The data of 2 patients previously reported elsewhere19 are also included in this analysis. However, none of the other neonates and infants reported in our previous studies13,15–18,23,24,26–28 are included in this analysis.
Of the 18 neonates in whom transumbilical BA was attempted, the balloon catheter could not be negotiated via the umbilical artery in 2 neonates (11%) and the remaining 16 neonates constituted Group I. These 2 neonates, along with 24 other infants, underwent transfemoral artery BA; these 26 infants formed Group II. Nine infants had anterograde transvenous balloon dilatation and will be referred to as Group III. The age, weight and gender data are listed in Table 1 and associated cardiac defects are listed in Table 2.
Balloon angioplasty. Balloon dilatation was performed using 6 mm (n = 35), 7 mm (n = 12) or 8 mm (n = 4) diameter balloons, all 2 cm long. In Groups I and II, the balloon catheter was positioned across the coarcted aortic segment from the descending aorta. In the anterograde femoral venous patients (Group III), the catheter was advanced from the right ventricle through the ventricular septal defect into the aorta in 5 patients, directly from the single (double-inlet left) ventricle into the aorta in 1 patient and directly from the right ventricle into the neo-aorta in 3 post-Norwood, hypoplastic left heart syndrome patients. Balloon aortic valvuloplasty was performed concurrently in 2 infants, reducing aortic valve gradients significantly.
Immediate results. Significant reduction (p 20 mmHg (reduced from 72–26 mmHg), but the infant had remarkable symptomatic improvement and therefore it was felt that no immediate reintervention was necessary. One neonate (2%) from Group I required surgical repair of coarctation 5 days after BA. At the same time, banding of the pulmonary artery was performed in this neonate with double-inlet left ventricle with L-transposition of the great arteries. Three infants (6%), two from Group II and 1 from Group III, rapidly developed recoarctation requiring surgical repair 3, 3.5 and 4 weeks after balloon angioplasty, respectively. The remaining infants improved symptomatically and did not require intervention within the first 4 weeks following BA. Thus, successful palliation, as defined above, was achieved in 47 of 51 infants (92%).
Complications. There was no mortality related to the procedure. Blood loss (during catheter/guidewire exchanges) requiring transfusion occurred in 5 of 51 patients (10%). Three (11.5%) were from Group II and 2 (11%) were from Group I (p Follow-up. Follow-up data were available in all infants for >= 1 month. However, three infants were lost to follow-up after their 1-month visit. At that visit, no evidence for coarctation was present in these 3 infants. The remaining 44 infants were followed for 5 months to 5.5 years (median, 3 years).
Recurrence and its management. Recoarctation (peak gradient > 20 mmHg)24,27 was observed in 22 of the 44 patients (50%). There was no clinical or echocardiographic evidence for recoarctation in the remaining patients. Recoarctation developed 2–10 months (median, 3 months) after BA. Surgical repair was undertaken in 8 infants without any complications. Repeat balloon angioplasty was performed in the remaining 14 infants. The diameter of the balloon used for repeat BA is generally larger by 1–3 mm (median, 2 mm) than that used at the time of initial BA. Following BA, the peak-to-peak gradients across the coarctation were reduced from 54 ± 20 mmHg to 9 ± 7 mmHg (p Other procedures and events. During follow-up, a number of catheter interventional and surgical procedures were undertaken and include balloon aortic valvuloplasty (n = 3), blade atrial septostomy (n = 1), surgical resection of fixed subaortic stenosis (n = 4), bi-directional Glenn anastomosis (n = 4), repair of ventricular septal defect (n = 3), Ross procedure (n = 2), Damus-Kaye-Stansel (n = 1), mitral valve replacement (n = 1) and Fontan operation (n = 2). Also, three large ventricular septal defects closed spontaneously and 2 defects became very small so that surgery was not required. All 12 infants who presented with left ventricular dilatation and poor function gradually improved; the size and function of the left ventricle returned to normal 3–6 months following BA.
Complications during follow-up. Careful review of follow-up angiograms performed in 24 patients did not reveal aneurysms. Femoral artery blockage was observed in 4 patients, but there was good collateral circulation. No evidence for leg length discrepancy29 was observed. There were no other complications.
Late follow-up. Long-term follow-up, defined as > 2 years, was available in 31 of 48 study subjects (65%). No late recurrences were detected. Arm-leg blood pressure gradients were 4 ± 6 mmHg (range, 0–15 mmHg). Right arm systolic blood pressures were 98 ± 11 mmHg (range, 82–114 mmHg). Four patients (8%) had systolic pressure greater than 95th percentile for age. Two children (4%) were receiving propranolol for control of blood pressure. None of the other children are on medication for treatment of aortic coarctation.
Group differences. The age of the UA patients (Group I) was lower (p 0.05). This trend may be related to differences in age at angioplasty, 6 ± 3 days in Group I vs. 57 ± 32 days in Group II; p 13,15–19,28 we have, at our institution, adopted a policy to apply BA as a first-line therapeutic option in the management of sick neonates and infants with AC. Similar experiences were also reported by other investigators.30,31 The purpose of this study is to determine if effective palliation is indeed achieved. With the exception of 4 infants (8%) who required surgical relief of AC within 4 weeks of BA, effective palliation, as defined above, was achieved in the remaining infants (92%). However, reintervention either by surgery (n = 8) or by repeat BA (n = 14) was necessary in 22 infants (50%); such reintervention was undertaken electively when the infant was stable, mainly to treat systemic hypertension. The high incidence of recurrence that we observed in this group of patients is similar to that previously reported by us24,28 and others.14,30,31 However, as we have emphasized since our very first report on balloon angioplasty more than 15 years ago,15 “the important feature of balloon angioplasty in the neonate and young infant is that it produces abatement of symptoms of heart failure and hypertension and helps avoid immediate surgery. Should recurrence ensue, it can be treated by repeat balloon angioplasty or even surgery, if one prefers, when the infant is stable and less acutely ill.” Early failures can be effectively managed by surgical intervention. Late failures (recurrence) can be managed either by surgical intervention32 or repeat balloon angioplasty.33
Failure to advance a balloon angioplasty catheter via the umbilical arteries to the coarctation site occurred in 2 of 16 patients (11%). This problem occurred in our early experience while we were using Proflex-5 and Meditech catheters and has not occurred since we began using highly trackable, low profile Tyshak-II catheters. Therefore, we use/recommend only the Tyshak catheters for transumbilical arterial balloon dilatation procedures.
Despite the younger age of Group I patients, the immediate relief of obstruction was similar in all groups, as was the recurrence rate. However, when recurrence in neonates (age 5,6,23,26,28 indicate that both modes of therapy are comparable in terms of effectiveness and safety. Balloon dilatation, however, has less morbidity and a lower complication rate.5,28 Based on the current study and the review of comparative data, we conclude that BA has an important role in the management of sick neonates and infants with aortic coarctation and that BA is an effective and safe alternative to surgical therapy of native coarctation. BA is particularly useful in situations where avoidance of anesthesia and/or aortic cross-clamping is beneficial, such as infants presenting in shock-like syndrome,18 poor left ventricular function with “hypertensive cardiomyopathy” associated with coarctation,17 prior cerebrovascular accidents6 and severe liver dysfunction.6Study limitations. This is a retrospective analysis of our experience and has the limitations of any retrospective study. Some variability of selection of patients and selection of mode of therapy, particularly for reintervention, exists and is related to bias of the primary cardiologist directing the therapy. However, since we have researched BA of native coarctation since mid-1980, a methodical process of data collection and patient selection has been incorporated into the continuing clinical practice and negates some of the limitations mentioned above. The inclusion of post-Norwood patients (n = 3 in Group II) may be critiqued, but because these coarctations are distal to the site of aortic arch reconstruction during the Norwood procedure, we felt justified in including these 3 patients as native coarctations.
Speculations/future directions. Although prompt relief of obstruction and effective palliation is achieved, some problems remain and include recoarctation and femoral artery compromise.
Causes of recoarctation. Causes of recoarctation following balloon angioplasty have been extensively investigated,27,34,35 and factors predictive of recoarctation have been identified; these include young age and severely narrowed isthmus and coarcted segment. More recently, studies of biophysical characteristics of the coarcted segment revealed less recoil in the subset of recoarctation patients, implying that the elastic properties of the aortic wall are not preserved.36 This may be related to cystic medial necrosis37,38 or to extension of the ductal tissue into the aortic wall.39–41 However, the fundamental cellular mechanisms responsible for recoarctation remain elusive.
Prevention of recoarctation. The cellular pathophysiologic mechanisms responsible for recoarctation have not been identified. Once they are identified, appropriate treatment algorithms to prevent recoarctation could be developed to address the pathophysiology. Until such time, keeping coarcted segments open by stents is an attractive option.42 Unfortunately, the stents, which are metallic, do not grow with the child, and therefore could not routinely be used in neonates and infants. Biodegradable stents43 may offer a solution; the stents will keep the coarcted aortic segment open for a 3–6 month period, when the stents would dissolve. By that time, the ratio of the normal aortic tissue vs. abnormal tissue may be in favor of the infant, thus preventing recurrence of significant narrowing. However, testing this hypothesis in appropriate animal models and miniaturization of stent delivery systems such that they can be used in neonates and young infants should be undertaken in the future.
Femoral artery obstruction. Use of large-caliber angioplasty catheters resulted in significant femoral artery compromise.44–46 Availability of balloon catheters that can be introduced through 4 Fr sheaths appears to reduce the femoral artery injury. More recent availability of balloon dilatation catheters that can be introduced through 3 Fr sheaths (for example, Mini-Tyshak catheters) may further reduce such complications. Detailed immediate and follow-up studies29 to confirm this thesis should also be organized in the future.
Summary and conclusions
Analysis of data on 51 consecutive BA procedures in neonates and infants Acknowledgment. The authors thank the members of the Divisions of Neonatology and Pediatric Cardiac Surgery at Saint Louis University School of Medicine/Cardinal Glennon Children’s Hospital, St. Louis, Missouri, for their contribution to the care of the patients in the study group including placement of umbilical artery catheters by the neonatologists. Thanks are also due to Kay Thompson for her assistance in preparing the manuscript.
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