Asian Cardiovasc Thorac Ann 1999;7:40-45
© 1999 Asia Publishing EXchange Pte Ltd
Critical Pulmonary Stenosis in Infants and Neonates in the Era of Interventional Cardiology
Abdul Aziz Bilkis, MD,
Mazeni Alwi, MRCP,
Samion Hasri, MD,
Abdul Latif Haifa, MD,
Kandhavel Geetha, MRCP,
Hafiz IA Law, FRCS1,
Department of Cardiology Malaysia
1 Department of Cardiothoracic Surgery National Heart Institute Kuala Lumpur, Malaysia
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For reprint information contact: Mazeni Alwi, MRCP Tel: 60 3 298 1333 Fax: 60 3 292 8425 email: mazeni{at}ijn.com.my Department of Cardiology, National Heart Institute, 145 Jalan Tun Razak, Kuala Lumpur 50400, Malaysia.
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Abstract
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Between September 1992 and February 1998, 22 consecutive patients aged 4 to 90 days with critical valvular pulmonary stenosis underwent percutaneous transluminal balloon valvuloplasty. Sixteen were cyanosed and 7 required prostaglandin infusion. The pulmonary valve was successfully crossed in all patients. Progressive dilatation was used to attain a final balloon to valve ratio between 1.2 and 1.4. Mean right ventricular systolic pressure dropped from 109 ± 26 to 34 ± 1 mm Hg. Oxygen saturation increased from 84% ± 8% to 98% ± 2%. There were 5 complications including 1 death due to valvular damage, 1 hemopericardium requiring drainage and transfusion, significant blood loss during cannulation in 2 cases, and a fractured guidewire that was retrieved in another. Repeat valvuloplasty was performed in 2 patients. Two patients required surgery; one had a dysplastic pulmonary valve with persistent pulmonary stenosis and the other had a hypoplastic right ventricle. Of the 20 patients who had valvuloplasty alone, 17 (85%) remained well with a mean peak systolic Doppler gradient of 30 ± 26 mm Hg and no pulmonary regurgitation. We concluded that valvuloplasty is likely to be the only procedure necessary for the majority of infants and neonates with critical pulmonary stenosis. However, surgery is required in cases of dysplastic pulmonary valve or hypoplastic right ventricle.
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Introduction
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Since percutaneous transluminal balloon valvuloplasty was first introduced in 1982, many reports have demonstrated its safety and efficacy as a nonsurgical treatment for congenital pulmonary valve stenosis and it is now considered the treatment of choice in children and adults.1–3 There is no consensus regarding the most appropriate management protocol for neonates with critical pulmonary stenosis. In these patients, balloon valvuloplasty is associated with higher rates of procedural failure and complications, resulting in a number eventually requiring surgery.4 However, this has been the preferred mode of treatment in many institutions on the basis that surgery in this group of patients is not without mortality and morbidity and carries risks that are comparable to, if not higher than, those of the transcatheter method.5,6 We report our 5-year experience in the management of neonates and infants with severe critical pulmonary stenosis.
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Patients and Methods
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From September 1992 to February 1998, percutaneous transluminal balloon valvuloplasty was attempted in 22 consecutive infants with clinical and echocardiographic diagnosis of severe critical pulmonary stenosis admitted to the National Heart Institute. We used the following definition of critical pulmonary stenosis: valvular pulmonary stenosis with pinhole orifice; suprasystemic right ventricular (RV) pressure or associated severe tricuspid regurgitation in patients with a ratio of RV to aortic systolic pressure greater than one and age below 3 months. We chose 3 months as a cutoff age instead of 1 or 2 months as used by others because there is a tendency for late referral of infants born in small rural clinics. The babies ranged in age from 4 to 90 days (mean, 30 days) and in weight from 2.2 to 7.5 kg (mean, 3.8 kg). Sixteen (70%) of these babies were clinically cyanosed and 7 (35%) were receiving a prostaglandin E1 infusion. The mean peak systolic Doppler gradient prior to valvuloplasty was 92 mm Hg. Tricuspid regurgitation was severe in 5 (23%) and moderate in another 5.
Percutaneous transluminal balloon valvuloplasty was performed under general anesthesia in all cases. Following right heart catheterization, biplane RV angiography was carried out. The pulmonary valve annulus was measured in the lateral projection. After confirming the diagnosis, an attempt to cross the valve was made by positioning a 5F Judkins right catheter (CORDIS Europa NV, Roden, The Netherlands) or less frequently a 5F multipurpose catheter in the RV outflow tract using a 0.014 inch steerable floppy-tipped coronary guidewire (ACS Inc., Temeluca, CA, USA). Once the valve was crossed, the guidewire tip was positioned preferably in the descending aorta via the ductus or if this was not feasible, in either the right or left pulmonary artery. Usually, a progressive dilatation strategy was employed, beginning with a 2-mm to 4-mm coronary balloon catheter followed by the appropriate size of balloon for the measured annulus size, aiming for a balloon to annulus ratio between 1.2 and 1.4. In one patient, two 4-mm coronary balloon catheters were delivered over an 8F Mullins sheath (Cook, Inc., Bloomington, IN, USA) after unsuccessful preliminary dilatation using a single coronary balloon because of failure to position the larger balloon squarely over the valve (Figure 1
). Generally, prostaglandin E1 infusion was discontinued the next day. Repeat hemodynamic measurements were made after completion of the procedure. Doppler echocardiographic evaluation of the residual systolic pressure gradient across the pulmonary valve and the degree of tricuspid regurgitation were performed the next day and at subsequent follow-up examinations.
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Results
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The pulmonary valve was crossed and dilated in all cases (100%). The mean valve annulus was 7 mm (range, 4 to 11 mm). The mean (± standard deviation) RV systolic pressure decreased from 109 ± 26 mm Hg (range, 53 to 200 mm Hg) to 34 ± 1 mm Hg (range, 23 to 100 mm Hg) and the mean RV to aortic systolic pressure ratio decreased from 1.2 to 0.6 (Figure 2). The mean gradient decreased from 85 mm Hg (range, 25 to 140 mm Hg) to 34 mm Hg (range, 0 to 80 mm Hg) as shown in Figure 3. The post-procedure RV to pulmonary arterial systolic gradient remained greater than 50 mm Hg in 7 patients but at subsequent follow-up examinations the Doppler-derived peak systolic gradients dropped to below 25 mm Hg in 5 of them, one underwent repeat balloon valvuloplasty, and the other underwent surgical valvotomy of the dysplastic valve. The mean systemic oxygen saturation increased from 84% ± 8% to 98% ± 2%. The mean fluoroscopy time was 26 ± 15 minutes (Table 1).
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Figure 2. Simultaneous right ventricular (RV) and aortic (AO) pressure tracings. (A) Suprasystemic RV pressure before balloon valvuloplasty. (B) Improvement in AO and a marked reduction in RV pressure following valvuloplasty.
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Figure 3. Changes in right ventricular to pulmonary arterial (RV–PA) pressure gradient following balloon valvuloplasty.
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There were 2 major complications, one of which resulted in death. One patient developed cardiac tamponade and exsanguination following rupture of the pulmonary valve annulus. The patient succumbed in the operating room during preparation for surgical repair. It was felt that use of a balloon that was too large in relation to the size of the annulus was the cause of this grave complication. The pulmonary valve annulus measured 8 mm and a 14-mm balloon catheter was employed for final dilatation because the selected more appropriate 12-mm balloon catheter could not be tracked over the guidewire due to its small lumen. Another patient developed hemopericardium that required drainage and blood transfusion immediately following the procedure. He was successfully resuscitated and recovered well with no long-term sequela. Significant blood loss requiring transfusion during cannulation was encountered in 2 patients. In one patient, the guidewire fractured during the procedure. This was successfully retrieved without any untoward effect on the patient.
Among the 22 babies who underwent balloon valvuloplasty, 2 (9%) required surgery. One patient who had moderate hypoplasia of the right ventricle remained dependent on prostaglandin E1 for 2 weeks after successful valvuloplasty. She was given a modified right Blalock-Taussig shunt. The other patient underwent surgical valvotomy for a dysplastic pulmonary valve.
Nineteen patients were followed up for 6 months to 3 years. Two patients died subsequently of causes considered to be unrelated to the procedure; one had multiple congenital anomalies and in the other, the cause of death was not confirmed. Of the 20 patients who underwent balloon valvuloplasty alone, 17 (85%) were well, acyanotic, and without evidence of significant residual obstruction and 2 underwent repeat valvuloplasty at 12 and 17 months respectively, after the first procedure because of significant residual stenosis. The peak systolic Doppler pressure gradients were 74 and 88 mm Hg respectively, prior to the second procedure. At the latest follow-up, 6 patients had mild tricuspid regurgitation and 1 had moderate regurgitation.
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Discussion
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The Valvuloplasty and Angioplasty of Congenital Anomalies registry of balloon dilatation for pulmonary stenosis was established with several goals including determination of the safety and efficacy of the procedure following its successful initial results. One of the findings that emerged from this registry was that complications were more common in neonates than in older subjects.7 The reported mortality from this registry of 822 balloon pulmonary valvuloplasty procedures was 3.5% and major complications including cardiac perforation with tamponade, tricuspid insufficiency, vein tears, and leaflet avulsion occurred in 3.5%; almost all of these occurred in neonates and infants. Although details regarding the severity of the lesions in these neonates were not available, presumably, these were cases of severe critical pulmonary stenosis requiring early intervention.
From reports early in the balloon valvuloplasty era and even later, the mortality rates from various forms of surgery to relieve severe RV outflow obstruction by closed or open valvotomy, with or without cardiopulmonary bypass, were considerably high.8–10 In a more recent prospective multi-institutional report involving 101 babies with severe critical pulmonary stenosis, the mortality rate in 62 who underwent surgery using a variety of techniques was 22.6%, whereas the mortality rate among 34 who underwent balloon dilatation was 6%.11 It is perhaps in the light of this experience and the rapid improvement in the results of balloon valvuloplasty that this procedure remains the preferred mode of treatment in many institutions.5,12,13 In our series, one death (5%) occurred due to rupture of the valve annulus leading to exsanguination. This was potentially avoidable had we been able to use a smaller size of balloon catheter. A major complication in the form of severe hemodynamic decompensation occurred in another patient but this responded well to resuscitation without any long-term sequela.
From the technical point of view, one of the drawbacks of balloon valvuloplasty is the potential failure to cross the pulmonary valve with a guidewire. As a result, the procedure has to be abandoned and the patient subjected to surgery. This was experienced in nearly half of the attempted balloon valvuloplasty procedures in some of the earlier series.4,14 However, with improvement in the equipment available in a modern catheterization laboratory and modification of the technique for small infants, this high failure rate has been considerably reduced.14–16 Using the Judkins right coronary catheter and the steerable floppy-tipped 0.014 inch coronary guidewire, we had no problem in crossing the pulmonary valve in all cases. In almost every patient, preliminary dilatation was performed with a 2-mm to 4-mm low-profile coronary angioplasty balloon catheter to minimize hemodynamic disturbance and ease subsequent passage of the large balloon catheter.
In spite of the much improved ability to deliver and correctly position the balloon catheter over the stenotic valve, a small number of patients will still require surgical intervention. This is especially the case in patients with severely dysplastic immobile valves where balloon valvuloplasty may not be effective in reducing the transpulmonary gradient.17 In patients with associated hypoplasia of the right ventricle, a systemic-to-pulmonary shunt may still be required despite virtual elimination of RV outflow obstruction, although this is much less commonly encountered in patients with critical pulmonary stenosis compared to those with pulmonary atresia with intact septum.11,18 In patients with a small pulmonary valve annulus, a more aggressive transannular patching technique may be necessary to adequately relieve RV outflow obstruction, although this is not a common surgical indication.11 In our series, 2 infants (9%) required surgery. One underwent surgical valvotomy and the second patient who had RV hypoplasia received a modified right Blalock-Taussig shunt because of persistent cyanosis after successful balloon valvuloplasty. It remains to be seen in the long term whether this patient's right ventricle will grow sufficiently to independently support the pulmonary circulation.
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Conclusion
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We concluded that percutaneous transluminal balloon valvuloplasty is effective and safe as the procedure of first choice in the treatment of neonates and infants with critical pulmonary stenosis. It is likely to be the only procedure necessary for the majority of these patients. However, we have no surgical control group with which to compare the results and surgery still has a major role to play in patients with a severely dysplastic valve, hypoplastic right ventricle, or a small pulmonary valve annulus where balloon valvuloplasty alone is unlikely to be effective in relieving RV outflow obstruction or eliminating clinically significant cyanosis as a result of unresolved tricuspid regurgitation and right-to-left atrial shunting.
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References
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Abstract
Introduction
