Age categorisation

The studied patients were categorised into three age groups: neonates and early infants (282 patients, 23.5%), infants (362 patients, 30.2%), and children (556 patients, 46.3%). Similar studies also use this age categorisation, as there is a wide range of variation in the outcome of balloon pulmonary valvuloplasty within each age group. Holzer group classified their population to neonatal and post-neonatal groups.^{Reference Holzer, Gauvreau and Kreutzer9} Ghaffari group also used age categorisation in their study.^{Reference Ghaffari, Ghaffari, Ghaffari and Sgafy10}

In our study, the smallest baby was 2.4 kg, while the maximum body weight was 40.7 kg, with a mean of 10.1 ± 8.9 kg. These results are comparable to those of Behjati et al., who reported a mean weight of 12.2 ± 4.7 kg (age ranged from 0.4 to 8 years).^{Reference Behjati, Seyed and Shahrokh11}

Transvalvular gradient

Initially, most haemodynamic data of patients with pulmonary valve stenosis were obtained from echocardiography. Gielen et al. mentioned that the use of Doppler echocardiography allows a reliable assessment of stenosis in all age groups.^{Reference Gielen, Daniels and van Lier12}

Regarding the echocardiographic data obtained before balloon pulmonary valvuloplasty, the mean pressure gradient across the pulmonary valve in all age groups was approximately 86.43 ± 25.66 mmHg (minimum pressure gradient 45 mmHg and maximum pressure gradient 188 mmHg).

Balloon pulmonary valvuloplasty was attempted in all patients with a peak-to-peak systolic gradient ≥45 mmHg at catheterisation; this criterion is in accordance with most published data, which considers a peak-to-peak gradient of approximately 50 mmHg as an absolute indication for balloon pulmonary valvuloplasty.^{Reference Handoka and El-Eraky13}

In 13 patients, this gradient was lower when determined by pullback pressure gradient assessment, and thus, balloon dilatation was not indicated. Those patients were followed up regularly and none of them required intervention.

Associated cardiac lesions occurred in 50.2% of our patients (602 patients) (Table 2).

Concerning the pressure gradient across the pulmonary valve assessed by catheterisation, in approximately 54% of our study group, readings were 20% less than those obtained by echocardiography, while in approximately 16.8% of the patients, the pressure gradients assessed by catheterisation were 30–50% less than those obtained by echocardiography. This finding reveals that the pressure gradient measurements by echocardiography should be re-evaluated by catheterisation before balloon pulmonary valvuloplasty, even if the readings obtained by echocardiography were indicative of balloon pulmonary valvuloplasty, especially in borderline cases (Figure 2).

Figure 2.

Details of the pressure gradient difference before and after balloon pulmonary valvuloplasty.

Balloon size

Concerning the selection of the balloon size, at first, we started using balloons that are 1.5 times the size of the pulmonary valve annulus, as we progressed further we are currently using balloons that are 1.2 times the size of the pulmonary valve annulus which was in concordance with most of the published studies in this field. Rao also recommended this balloon size on the basis of immediate as well as follow-up results.^{Reference Rao3} Balloons larger than 1.5 times the pulmonary valve annulus can damage the right ventricular outflow tract; furthermore, these balloons do not have an advantage beyond that produced by balloons that are 1.2–1.4 times the annular size, which is why such large balloons should not be used. However, large balloons with a balloon/annulus ratio of 1.4:1.5 can still be used when dilating dysplastic pulmonary valves. The balloon/annulus ratio in the patients whose right ventricular pressure dropped to more than half was 1.23 ± 0.24 mm, while it was 1.27 ± 0.25 mm in other patients.

Recommendations for the use of 20-mm-long balloons in neonates, 30-mm-long balloons in infants, and 30–40 mm long balloons in children were followed. Rao also used similar balloons in each age group. However, Rao reported that there are no data supporting that a given length balloon is more successful than other lengths in relieving an obstruction. With short balloons, it is difficult to maintain the balloon centre across the pulmonary valve annulus during balloon inflation. However, long balloons may impinge upon the tricuspid valve, causing tricuspid insufficiency, or affect the conduction system, causing heart block.^{Reference Rao3}

The mean diameter of the pulmonary valve annulus, as assessed by echocardiography before balloon pulmonary valvuloplasty in most of our patients) 81.3%), was ≤2 mm shorter than the mean diameter measured by angiography (976 patients). This finding suggests that we can depend on echocardiographic measurements to select the proper balloon size for the procedure.

Handoka and El-Razky mentioned that the balloon size was determined according to the maximum internal diameter of the pulmonary valve from hinge point to hinge point during systole as measured in the lateral projection of the right ventricular angiogram with corrections for magnification.^{Reference Handoka and El-Eraky13}

In our study group, sequential balloon valvuloplasty using two consecutive balloons were used in 30.8% of the total number of patients (370/1200), most of whom were children (146 patients). Saad et al. reported the use of two consecutive balloon inflations in 56% of infants in their study group.^{Reference Saad, Roushdy and Elsayed4}

Rao mentioned that Tyshak II balloons are most commonly used by interventional cardiologists, as they have the widest range of balloon sizes and diameters available in this line of catheter.^{Reference Rao3} In our study group, Tyshak II balloons were used in 58.5% (702/1200) of patients as the first balloon, and 57.3% (212/370) of patients when two balloons were used.

Outcome of balloon valvuloplasty

Regarding the outcome of balloon pulmonary valvuloplasty, in approximately 52.8% of our study group, the pressure gradient across the pulmonary valve dropped by more than 50% of the pre-catheterisation values (634 patients), while in approximately 35.3% of our study group, the pressure gradient dropped to 30–50% of the pre-catheterisation values (424 patients). We considered balloon pulmonary valvuloplasty as successful when the pressure gradient across the pulmonary valve drops to half or more than that of the pre-catheterisation values. In addition, Rao defined the intervention as effective if it decreased the stenosis by at least 50% of the initial value.^{Reference Rao3} Other authors consider the intervention to be successful if the transvalvular peak gradient dropped to <36 mmHg.^{Reference Handoka and El-Eraky13}

In this study, patients had a significant reduction in the right ventricular systolic pressure from 107.81 ± 30.88 mmHg to 54.92 ± 20.74 mmHg as well as in right ventricular systolic pressure – pulmonary artery pressure from 86.43 ± 25.66 mmHg to 28.15 ± 16.68 mmHg immediately after balloon pulmonary valvuloplasty. This finding is in accordance with that of Behjati et al. who reported a reduction in the peak-to-peak systolic pressure gradient across the pulmonary valve from 83.28 ± 32 mmHg to 19.3 ± 14.2 mmHg.^{Reference Behjati, Seyed and Shahrokh11}

Our success rate is approximately 82.7% (992/1200), with the best success rates within the children age group (84.5%). Our success rate is comparable to that of Ahmadi and Sabri, who reported an immediate dilation success rate of 77%.^{Reference Ahmadi and Sabri14} The success rate was reported to be 88.9% in the study by Liu et al.,^{Reference Liu, Wu and Huang15} while a success rate of 90% was reported in the study of Jaing et al.^{Reference Jaing, Hwang, Lu, Hsieh and Meng16} Our findings and the results of previous studies indicated the effectiveness of balloon pulmonary valvuloplasty in the treatment of pulmonary valves.

However, Larry reported that the initial success does not guarantee that the pressure gradient will remain the same, as most of the studies reported that approximately 15–30% of patients with an initially successful balloon pulmonary valvuloplasty may show evidence of significant residual or recurrent right ventricular outflow tract obstruction within 1–2 years. Repeated balloon pulmonary valvuloplasty is successful in many of these patients. However, up to 10% of patients may eventually require surgical right ventricular outflow tract resection or pulmonary valve resection. This finding confirms that close follow-up of the successful cases should be performed.^{Reference Larry17}

In our study group, approximately 13.7% of patients (165 patients) underwent another balloon dilation by repeat catheterisation, 3.6% of patients were referred for surgical valvotomy (43 patients), and 8 patients underwent both repeat catherisation and surgery after balloon pulmonary valvuloplasty. This finding is comparable to that of Peterson et al. who reported the development of restenosis in 13 patients who underwent balloon pulmonary valvuloplasty (14.1%); 6 patients were re-dilated and 7 patients required surgery (108 patients with a mean age of 3.6 ± 3.9 years were included in their study).^{Reference Peterson, Schilthuis, Dodge-Khatami, Hitchcock, Meijboom and Bennink18}

Complications of balloon valvuloplasty

Regarding the complications of balloon pulmonary valvuloplasty, we reported a total percentage of approximately 8.5% of complications (102 patients) during the catheterisation procedure. Some of these patients had multiple complications. The most common complication was perforation of the right ventricular outflow tract that resulted in either minimal pericardial effusion (usually resolved spontaneously or after pericardiocentesis) or massive pericardial effusion. Cardiac arrest and near arrest occurred in 10 patients (0.8% of the studied group) and were resolved with successful resuscitation trials. This rate is in close agreement with that reported by Tggart et al.; in that report, 11% of the 89 patients in the paediatric study group had periprocedural complications (10 patients), and perforation/pericardial effusion was the most common complication (3 patients).^{Reference Tggart, Cetta, Cabalka and Hagler19}

Larry reported that a wide variety of complications has been observed over the years in attempted treatment of pulmonary valve stenosis with balloon pulmonary valvuloplasty. In early reports from the 1980s, the available balloon valvuloplasty catheters were considerably larger and stiffer than the present generation of catheters. Vascular complications, including retroperitoneal haematomas and avulsions of the iliac vein, were previously encountered, but these complications should be extremely rare with the new generation of valvuloplasty catheters.^{Reference Larry17}

Balloon valvuloplasty in neonatal age group

Regarding balloon pulmonary valvuloplasty in the neonatal and early infancy age group, approximately 23.5% of our studied patients (282/1200 patients) were neonates with a mean age of approximately 26.7 ± 6.97 days and a mean weight of approximately 4.7 ± 1.4 kg (the minimum weight was 2.4 kg).

The mean pressure gradient across the pulmonary valve by echocardiography before balloon pulmonary valvuloplasty was 91.9 ± 23.4 mmHg.

Bernstein reported that when severe pulmonary valve stenosis occurs in a neonate, markedly decreased right ventricular compliance may lead to right-to-left shunting through a patent foramen ovale, a condition termed critical pulmonary stenosis. The mean pulmonary valve annulus diameter was 7.8 ± 1.7 mm,^{Reference Bernstein, Behrmen, Kliegman and Jenson20} which is in accordance with that in the study group of Holzer et al., which had a median diameter of 6.9 mm (4–9.5 mm).^{Reference Holzer, Gauvreau and Kreutzer9}

A total of 282 neonatal patients underwent balloon pulmonary valvuloplasty in our study. The most commonly used balloon was the Tyshak II balloon, and approximately 16 of those patients needed another consecutive balloon dilation.

Holzer et al. reported a success rate of around 96% (92 patients) in his <1-month study group (96 patients). Holzer attributed this slightly high procedural success rate to the fact that in neonates with critical pulmonary stenosis, a large patent ductus arteriosus is often present, leading potentially to increased pulmonary artery pressure and thus a reduced transvalvular gradient after the procedure.^{Reference Holzer, Gauvreau and Kreutzer9} Our success rate within this age group was approximately 78.7% (222/282 patients). This difference in outcome could be partially explained by the large number of patients in our study compared to other studies.

Repeat balloon pulmonary valvuloplasty was performed in approximately 29.8% of the neonates (84/282 patients), while Holzer et al. reported that 6% of his study group underwent re-intervention during the study period. The neonatal age group has a higher incidence of re-intervention in this study than in similar studies; their re-intervention rate is also higher than that of other age groups in this study.^{Reference Holzer, Gauvreau and Kreutzer9}

The pressure gradient across the pulmonary valve dropped after balloon pulmonary valvuloplasty to more than half of the pre-catherisation values in approximately 61.7% of the studied patients within neonatal age group (174/282 patients). The pressure gradient across the pulmonary valve dropped from 92.9 ± 29.2 mmHg to 30.1 ± 18.3 mmHg, while the right ventricular systolic pressure dropped from 115.5 ± 30.2 mmHg to 56.3 ± 20.1 mmHg immediately after balloon pulmonary valvuloplasty.

Complications during balloon pulmonary valvuloplasty occurred in approximately 21.6% of the studied group (61/282 patients). The most common complication was perforation. Transient cardiopulmonary arrest occurred in six patients of our study group but resolved with immediate and effective resuscitation efforts. This perforation rate was in close agreement with that in the study by Holzer et al., who reported complications in approximately 19% of his study group, but no deaths occurred. This high rate of complications can be partially explained by high haemodynamic vulnerability scores, increased use of vasoactive drugs, and severe pulmonary stenosis in this age group, especially in the early neonatal period. This finding suggests that this age group needs much more care during balloon pulmonary valvuloplasty and close follow-up immediately after the procedure.^{Reference Holzer, Gauvreau and Kreutzer9}

Predictors of success and complications

The work of Handoka and El-Eraky showed that the age of patients, associated cardiac lesions, and pre-balloon pulmonary valvuloplasty haemodynamic parameters (right ventricular systolic pressure, systolic pulmonary artery pressure, right ventricle to pulmonary artery pressure gradient) were not significant predictors of successful balloon pulmonary valvuloplasty in the studied patients.^{Reference Handoka and El-Eraky13} This result is consistent with that reported by Mendelsohn et al., who found no significant difference in these parameters between successful and unsuccessful balloon pulmonary valvuloplasty groups by comparing the age or weight. However, Mendelsohn et al. observed that the successful balloon pulmonary valvuloplasty group had significantly lower pre-balloon pulmonary valvuloplasty gradients and lower systolic pressure ratios than the unsuccessful balloon pulmonary valvuloplasty group.^{Reference Mendelsohn, Banerjee, Meyer and Schwartz21}

In our study, the absence of infundibular and supravalvular stenosis and a large pulmonary valve diameter were the most significant predictors of success. A minor immediate drop in pressure gradient across the pulmonary valve post-intervention was found to be a significant predictor for repeat catheterisation, the need for surgical valvotomy, and the occurrence of complications. This result is in agreement with that of McCrindle who reported that a high gradient immediately after the procedure predicted a suboptimal outcome.^{Reference McCrindle22} A higher right ventricular pressure pre-intervention was also found to be a significant predictor for repeat catheterisation and the occurrence of complications.

In addition, Silvilairat et al. observed that patients who achieved incomplete relief of the obstruction immediately after valvuloplasty had a higher baseline pressure gradient, higher RA pressure, and higher right ventricular systolic pressure than patients whose obstruction was immediately relieved.^{Reference Silvilairat, Pongprot, Sittiwangkul and Phornphutkul23}

In the multivariate analysis, the presence of supravalvular in association with valvular pulmonary stenosis, low weight, high right ventricular pressure before intervention, and a minor immediate drop in pressure gradient post-intervention were found to be the most significant predictors of the occurrence of complications.