INTRODUCTION

Patent ductus arteriosus (PDA) is common cardiac defect with incidence of 6–11 % ¹ Symptomatic PDA requires treatment in the form of medical as well as surgical intervention ². Trans catheter closure of PDA is considered to be safe and preferable now a days³. Cardiac catheterization was first used to treat PDAs in 1966 ⁴. Recently various types of duct occluder devices are available for PDA occlusion ⁵.

Ductus arteriosus persists in a wide variety of sizes and configurations. Krichenko et al. angiographically classified duct into five types: type A ‘‘conical’’ ductus, with ampulla at aorta and narrow point at the pulmonary end. Type B ‘‘window’’ ductus, with no ampulla and narrow end. Type C, ‘‘tubular’’ ductus. Type D, ‘‘complex’’ ductus, with several narrowing. Type E,‘‘elongated’’ ductus, with narrowing away from the anterior edge of the trachea ⁶.

The size, shape and associated cardiac defects are the main aspects to be considered in interventional closure. Various types of devices for PDA closure are now available. These include ADO device, Rashkind device, SHSMA occlude and Gianturco coil⁷. Lots of studies have been done on effectiveness and complications of various devices but little data is available regarding residual leak in normal versus reverse shank method. Moreover residual leak sometimes may be challenging to treat because of hemolysis, volume load, increase chance of infective endocarditis and re-coiling or re-devising.

METHODS & MATERIALS:

A cross sectional observational study with consecutive sampling was conducted in the cardiology department, Children hospital and Institute of Child Health Lahore, to evaluate the results of PDA device occlusion. The data of patients over last 6 months who underwent duct occlusion, were collected after approval from ethical committee on a pre-designed  performa. Age ranged between 6 months to 16 years. Cardiac catheterization was not offered to patients weighing less than 4 kg or patients associated with other cardiac problems required surgery.

Duct Occluder classification:

Performa was designed to focus on the angiographic types of PDA and residual leak between standard shank and reverse shank duct occluder used for the different types of PDA. The reverse shank duct occluder has wider pulmonary end than the aortic end while in normal shank aortic end is wider than pulmonary end. The devices used for standard shank were Life tech, Amplatzer AGA and SHSMA . While for reverse shank, Occlutech was used.

Device size selection:

No clear guideline available for selection of the size of a duct occluder. Most operators select devices at least 2 mm larger than the narrowest point of the duct ^8,9,. In selecting  size of duct occluder as standard, 2mm bigger than the narrow point was preferred in low pulmonary artery pressure while more than 4mm of the narrow point was preferred in case of moderate to severe pulmonary hypertension¹⁰.Duct length was measured from ampulla to narrow point ¹¹. We repeated angiography always after crossing with delivery system and re-measured narrow point before selection of size of device. By this technique, our embolization rate was reduced to zero.

Angiography:

PDA device closure was done under universal aseptic condition through femoral artery and venous approach. Heparin with 100 u/kg was given before start of procedure. In children below 7 months procedure was done under general anesthesia. While children above 7 months the procedure was done in local anesthesia and sedation. A full lateral view of Aortic angiogram (90^o LAO) was performed to determine the morphology and size of the duct. Sometime the shape was confirmed at 30^o RAO view also. The size of ampulla, narrow point, and length of duct was measured at both 90⁰   LAO, 30⁰ RAO angiogram .Initial measurement guided us for selection of size of delivery system .Both aortic, and pulmonary artery pressures were measured before selection of device. After crossing with delivery system, we re-measured the size narrow point. Device type and size was selected after reviewing the aortogram and pulmonary artery pressure by consensus of two-consultant pediatric cardiologist. Position of device was reconfirmed before releasing device through angiography by contrast media at both 90 LAO and if required then at 30 RAO view also. Immediate complication like LPA or aortic partial obstruction was confirmed by pull back gradient at ascending and descending aorta and LPA distal to proximal gradient by cather. The side leak not foaming through device was labelled as residual leak after 24 hours post procedure through echocardiography by consultant pediatric cardiologist.Hemolysis was ruled out by assessing clinical status and urine examination before discharge.

All the data was entered in SPSS version 25 software and then analyzed for statistically significant outcomes. Descriptive analysis and the Chi-Square test was applied to measure the association among the different categorical variable.

RESULTS:

The male to female ratio was 1:2 (Figure-1). The mean age of patients was ± 4.05 years with minimum age of 8 months, the mean weight of patients was ± 13.72 kg. The standard deviation of height was ± 27.01 cm. The mean narrow point of duct was 3.27mm with minimum range of ±1.4mm to 8.8mm. The minimum size of ampulla was ±1.4 mm to 20 mm. Regarding device selection according to narrow point ,in minimum size of 1.4 mm the average  device used was 3.0 mm while with maximum size of ampulla ie 8.8mm ,the average device size used was 16mm. The mean of aortic end to PDA diameter ratio was 2.6 with average of ± 0.96 - 7.14 mm.  Similarly, the mean of maximum device to PDA diameter ratio found was ±1.74 to 7.1 mm (Table-1).

Figure-1

Out of 79 patients, according to Krichenko angiographic classification of PDA, 45 patients had Type A shape, 7 patients had Type B, 17 patients had Type C, 4 patients had type D, and 6 patients had Type E angiographic shape (Figure-2). Regarding length of duct, only two patients had small length (≤4mm) while 46 patients had medium length ( 7mm) , and 31 patients had long length  (≥7 mm) Figure-3.

Table-1: Demographic data of Patients and angiographic duct and device measurement (n-79)

Table-2: Residual leak in normal versus reverse shank duct occluder in different shape of PDA.

Figure-2:   The types of duct according to Krichenko angiographic classification (n=79)

Figure-3:  Category of duct length (n-79)

Out of 50 patients in which regular shape duct occluder devices were used, 4 (8%) patients had residual leak in PDA. While out of 29 patients in which reverse shank device was used 7 (24%) patients had residual leak. Therefore, in reverse shank the frequency of leak was found higher than normal shank. According to Krinchenko angiographic classification of PDA, 6 patients had residual leak in type-A, 1 patient had residual leak in type-B, 3 patients had residual leak in type-C. No residual leak was seen in type D shape of PDA and in type -E shape 1 patient has residual leak (Figure-4).

Figure-4. Residual leak in angiographic shape of duct (n=79)

Regarding residual leak with reverse shank, the maximum residual leak was seen in type-A and type-C PDA (Table-2).Similarly, no residual leak in reverse shank was found in PDA type-B, type-D and type-E which indicated that reverse shank duct occluder was good in these shape of duct. Other complications like early embolization, hemolysis, aortic or LPA obstruction were not seen in our patients within 24 hours. The parameters like age, weight, height, minimum PDA diameter , diameter of Ampulla, Aortic end  to PDA diameter ratio, the device pulmonary end to PDA diameter  ratio and maximum device to PDA  diameter ratio all retain the null hypothesis and has no effect on the design of device and with residual PDA used (figure -5).

DISCUSION:

The reverse shank is designed to enhance the stability of device in the duct and decrease the risk of embolization. It is available in two different lengths, the standard length and the long shank device made for long ductal ampulla¹¹.Residual shunt through the reverse shank device was described in the literature. Excellent occlusion rates have been reported at 1 day (82%-97%), 1 month (96%-100%) and 6 months (96%-100%) follow up¹².Similarly, reverse shank showed higher incidence of residual leak than standard shank devices in our study as 8% found in standard shank device versus 24% in reverse shank device, which was supported by Kudumula V study. It was also reported that immediate ductal occlusion did not occur by using the ODO¹². A study revealed that there was only 48.5% complete occlusion rate at 10 minutes post-implant, but in large duct complete occlusion occurred till 90 days¹³. But in our study we found immediate occlusion rate within 10 minutes with all types of devices as 86% while with only ODO it was 76%. Another study also documented that immediate complete occlusion with ODO was 63%¹⁴. We had better occlusion rate in our study with ODO as mentioned, it was 76%. We had better implant technique possibly  due to repeat angiography every time  after crossing with delivery system and re-measuring narrow point before selection of size of device. Reyhan et al mentioned that especially in type –B and type-C oversizing measurement of device was better option¹⁴.We also noticed that in type-B and type-C only 14% patients showed residual leak because of oversizing technique.

Figure- 5

Regarding complication as early embolization of device it was documented that chance of embolization in large duct was always high^15,16. In our study there was no embolization seen.

CONCLUSION:

Reverse shank had higher incidence of residual leak in type A. However, regular shank device may be preferable in both Type A and C shape duct. Results were also comparable in both types of devices in type A, and C patent ductus arteriosus.

LIMITATIONS:

It was single center study .Follow up was not included regarding hemolysis, volume loaded, residual leak and infective endocarditis in long run. Outcome of re-devicing or coiling result were not mentioned .Fate of pulmonary hypertension after device and co-relation between residual leaks with pulmonary hypertension were not assessed. Similarly, type of device selection was purely on subject of availability.

ACKNOWLEDGE:

Thanks the support of our angiographer, and other staff members of angiography department. 

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