YM Ng, DML Wong, KC Chan, KS Lun, SH Lee, TH Goh

Abstract

In Hong Kong, we first used the retrograde technique of transcatheter closure of patent ductus arteriosus (PDA) with Gianturco coils and employed the balloon wedge pressure catheter method to stop embolization of coils in a prospective study. Fifteen consecutive patients, with mean age of 53.6 months and mean body weight 17.4 kg, were recruited. The narrowest diameter of the PDA ranged from 1.3 to 4.0 mm (median 2.6 mm). PDAs were closed retrogradely by coils while maintaining the balloon catheter inflated at the pulmonary end of the PDA to prevent embolization. Echocardiogram was performed at 24 hours and 3 months after the procedure. Nine patients had immediate complete closure and 6 patients had trace residual shunt at 24 hours after the procedure. Two patients had late closure at three month follow-up. The late closure rate was 73.3%. On follow-up, only one had a soft murmur. Recommendation on this catheter closure procedure of PDA was discussed.

Introduction

A persistent ductus arteriosus, as an isolated lesion, has been estimated to occur in between 1 in 2500 and 1 in 5000 live births. It represents between 9 and 12% of all presenting congenital heart lesions. In most series, there is a sex difference with a 2:1 female-to-male ratio.¹

Definitive treatment has been surgery since Gross and Hubbard² reported the first surgical ligation of PDA in 1939. There are reports of residual shunts or re-canalization after ligation.^3-4

Rashkind and Mullins described the application of the Rashkind PDA Occluder® System in 1987⁵ and this was followed by an abundance of publications on these catheter closure results using the double-umbrella devices.

However, many cardiologists have found this technique quite complicated, requires large introducer sheaths (8F or 11F) to deliver the device and is expensive. The double-umbrella device is not very suitable for small ductus closure. It is frequently associated with a residual shunt.^5-7 There are also a few important complications such as the development of left pulmonary artery stenosis and haemolysis. Furthermore, the Rashkind PDA Occluder® System became unavailable in the United States in the early 1990s because of concerns relating to fractures of the device.

Percutaneous closure of patent ductus arteriosus with occlusion coils has been reported to be an effective and safe therapeutic modality with low morbidity and mortality. Studies have shown that Gianturco coils have been used in transcatheter closure of PDAs with very favorable results achieving high closure rates ^6,8-10 especially in sma11 ductus. In Hong Kong, we first describe retrograde coil occlusion with the use of a inflated balloon wedge pressure catheter at the pulmonary end (technique introduced by Dr. TH Goh) of the PDA (Fig. 1a to f) to reduce the complication of coil embolization into the pulmonary arteries. A prospective study was carried out in Queen Elizabeth Hospital to evaluate the safety and efficacy of this technique.

Methods

Patients

All cases of PDA (total = 16) seen between November 1996 and July 1997 were included (one silent ductus was excluded), 15 patients (female 10, male 5) underwent elective occlusion of patent ductus arteriosus with Gianturco coils at Queen Elizabeth Hospital, Hong Kong. The mean age was 53.6±41.6 months (median 41 months, range 16 to 150 month); mean body weight was 17.4±8.1 kg (median 15.5 kg, range 9 to 38.3 kg). The mean narrowest diameter of the PDA was 2.44±0.79 mm (median 2.6 mm, range 1.3 to 4.0 mm) (Table). 14 of them (94%) were asymptomatic. One patient had symptoms of heart failure. Fourteen patients (94%) had isolated PDA and one had associated small ventricular septal defect. All patients were assessed by previous echocardiography and cardiac catheterization confirming the presence of small to moderate left to right shunt (by Q_p/Q_s ratio, Table). Consent was obtained from parents.

Technique

All procedures were performed under general anaesthesia. 5F arterial introducer sheaths were introduced into the right femoral vein and the right femoral artery with the Seldinger technique. This was followed by systemic heparinisation to prevent arterial thrombosis.

From the venous side, a 5F balloon wedge pressure catheter (B. Braun) was introduced. The tip of the balloon catheter was positioned close to the pulmonary end of the ductus with the help of a 0.025-inch Terumo flow-directed floppy guidewire. The guidewire was passed from the right femoral vein through the PDA and tip was positioned in the descending aorta (Fig. 1b).

Descending aortogram was obtained with a 5 French pigtail catheter to delineate the PDA in standard lateral view (Fig. 2a). The type¹¹ of the PDA was noted and the narrowest diameter of the ductus was measured. Gianturco coils of 0.038-in wire diameter (Cook Inc,) were used in all patients. The appropriate size Gianturco Coils (Cook) were then selected. The preferred coil should be at least twice the diameter of the narrowest part of the PDA. The length of the coil was sufficient to produce at least three loops, allowing half of a loop at the pulmonary artery end of the ductus.

A 5F Cobra catheter was advanced retrogradely into the main pulmonary artery through the ductus. The coil was then introduced through the Cobra catheter. The coil was advanced into the Cobra catheter by using the stiff end of a 0.038-inch guidewire (GW) (Cook) for a distance about 10 cm. Then the coil was advanced to the tip of the catheter that was in the main pulmonary artery with the soft end of the wire. Half of the first loop of the coil was then push out of the catheter by the 0.038-inch GW into the pulmonary artery (Fig. 1c). The cobra catheter and the coil were withdrawn until the half-loop reached the pulmonary arterial orifice of the ductus arteriosus.

This position was achieved when the extruded loop began to straighten or when the extruded loop failed to continue moving with the cobra catheter. The balloon was then inflated at this juncture in the pulmonary end to prevent dislodgment and embolization of the coil (Fig. 1d). The cobra catheter was carefully pulled toward the descending aorta while continuously pushing the coil with the GW until it was completely extruded into the ampulla of the ductus (Fig. 1e). Care was taken so that the half-loop was always maintained. The wedge balloon was kept inflated all the time during the push and pull manuvour. After the coil was released, the balloon was deflated (Fig. 1f). The satisfactory closure of the ductus was checked by hand contrast injection with the cobra catheter at the descending aorta at the ampulla. The procedure was repeated with a second or third coil if there was significant shunting of contrast through the ductus as shown by hand or machine injection of contrast. A descending aortogram was performed after satisfactory placement of the coils and occlusion of the PDA (Fig. 2b). With the careful push and pull of the Pigtail or Cobra catheter, coil repositioning maneuver was performed to optimally reposition the coil to achieve better occlusion.

Echocardiographic examination

All patients underwent echocardiographic studies with the Hewlett Packard Sono 1000 3.5 MHz or 5 MHz transducers 24 hours after the procedure. Residual shunts were detected by Color Flow Mapping (CFM) and Doppler. Echocardiograms were performed at 3 month after the occlusion to detect any residual shunts and turbulence in LPA and descending aorta.

Follow-up

All patients were followed for the presence of any significant murmur and any residual shunt by CFM. Antibiotic prophylaxis was recommended only for the first six months after complete occlusion of the PDA. For those patients who had persistent residual shunts, continuing antibiotic prophylaxis was recommended.

Results

All patients underwent successful coil implantation with one to three (variable number) coils. There were 10 females and 5 males. The mean age was 48.8±32.7 months (median 41 months, range 16 to 144 month); mean body weight was 17.4±8.1 kg (median 15.5 kg, range 9 to 38.3 kg). One patient had symptoms of heart failure requiring anti-failure treatment before the procedure. Fourteen patients had type A ductus while one patient had type B ductus. The narrowest diameter of ductus measured angiographically was 2.44±0.79 mm (median 2.6 mm, range 1.3 to 4.0 mm). Nine patients had complete closure as determined by descending aortogram at end of the procedure and by echocardiogram performed 24 hours after the procedure. On subsequent follow-up at three month, two of the six patients had complete closure of the ductus. Thus the early closure rate was 60% while the late closure rate was 73%. Residual shunts were very small and all except one had a soft systolic murmur at left upper sternal border and was detected by echocardiography in all four (Table). The continuous murmur was abolished in all 15 patients.

Follow-up results

For those patients who had residual shunt, sizes of the PDAs before occlusion were all larger than 3.2 mm. All patients were asymptomatic on follow-up. Physical examination showed only soft ejection systolic murmur in one and follow-up Color-Flow Mapping (CFM) showed trace residual shunts in four. For those ductus that had been occluded completely, there was no recurrence of the ductus and the coils stayed in perfect positions. Infective endocarditis prophylaxis was discontinued 6 months after complete closure.

Complications

There was no major complication. There was no loss of arterial pulses. There was no major bleeding nor death. None developed any intravascular haemolysis. There was no embolization into the pulmonary artery.

There were some technical problems in three patients during the procedure. Two patients had the coils pulled through the ductus (with part of the coil still in the cobra catheter) during the procedure and they required retrieval with a snare. One patient had the wedge balloon catheter looped inside aorta during manipulation of the catheter to reshape the coils. This was successfully disentangled with the use of retrieval snare. Two patients developed transient fever after the procedure. Blood culture did not grow any positive organism.

Discussion

Percutaneous transcatheter closure of patent ductus arteriosus with various kinds of occluders had been reported to produce variable success rates. Experience with various kinds of occluders has accumulated during the past years. The Rashkind double umbrella occluding device has been most extensively studied. However the system require larger size introducer sheaths and also complicated techniques. Moreover, problems exist when the device needs to be retrieved in case of device malposition. There are also incidents of intravascular haemolysis in cases with umbrella incomplete closure.

In contrast, occluding spring coils have recently been described to produce reliable results in closing small ductus.¹⁰ It has the advantage in that a smaller size introducer sheath (5F) is required. Hence it can be used for small infants without causing arterial or venous problem. The technique is easier to learn and the problem of embolization is minimized. In our series, this is avoided by the concurrent use of a balloon wedge pressure catheter placed at the pulmonary end of the PDA. The cost for the embolization coils is much cheaper and the duration of hospital stay is shorter.

Out of 15 patients with a ductal shunt (Table: Q_p/Q_s ratio ranged from 1.1:1 to 2.4:1, median 1.5:1), only 4 were left with a trace of shunting after coil occlusion.

There are a few points pertaining to this study for discussion. First, in this series the number of patients is small to allow for any statistical comparison. Second, the follow-up results are 3 months post-occlusion. Third, the results (i.e. the optimal number and sizes of coils placed, residual shunts) may be affected as one is climbing up the learning curve. As shown in our cases, there were 4 patients with residual shunts demonstrated by CFM yet soft ejection systolic murmur was detectable only in one patient. For those with small or trace residual shunts, the long term follow-up result and its significance is still pending (as regards later closure, infective endocarditis, etc.). There were silent residual shunts in 3/15 (20%) patients that are much less than Rashkind Occluder occlusion (38%) and it is quite similar to the incidence of residual shunting after surgical ductus ligation in 18% and 23% of patients in 2 series.^3-4 We have not got data to compare non-silent shunts frequency among the three methods. The natural history of silent residual ductal shunts in patients with ductal occlusion devices is unknown. If clinically significant (non-silent) ductal shunting was to persist beyond 6 months after coil implantation, additional coils may be used to produce complete occlusion.

Conclusion

The present study demonstrates that high closure rate could be safely achieved with the Gianturco coils. The immediate closure rate (within 24 hours) is 60% while the success rate continued to rise to 73% at three month follow-up. It is expected that the late closure rate at one year will be higher. It is a safe, effective and economic procedure with minimal complications. The concomitant use of a balloon wedge pressure catheter with the balloon inflated in-situ during the placement of the coils prevent coil embolization. The cost for the delivery of coils is much cheaper compared with the Rashkind umbrella⁷ and the hospital stay is short like any other diagnostic catheterization, that is 24 to 48 hours.

Thus, along with other reported experience,^6,8-10 we recommend transcatheter closure of small PDA (especially good for those that are less than 3 mm) with the Gianturco coil as the first choice of management. The use of balloon catheter occlusion we describe here completely eliminated embolization in our series.

Acknowledgements

We thank our cardiac registrars: Dr. KF Kwan, Dr. KW Lee, Dr. P Mak and Dr. PW Yau; the staff of the Department of Anaesthesia and cardiac catheterization laboratory for their excellent and dedicated work.

References

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