Embolization of Large Patent Ductus Arteriosus (> 4.0 mm) in Dogs with a Single Polyester Fibered Double-Helix Coil
Department of Clinical Studies, Small Animal Clinic (Internal Medicine and Surgery), Justus-Liebig-University Giessen
Coil embolization of large patent ductus arteriosus (PDA) is difficult, because coil stiffness is getting lower with increasing loop diameter. To increase coil-stiffness a Double-Helix configuration of the coil can be used. The aim of this prospective study was to prove the feasibility of embolization of large PDAs (> 4.0 mm) with a single polyester fibered Double-Helix coil.
Ten consecutive dogs with an angiographically determined minimal PDA diameter of > 4.0 mm were included independent on clinical status of congestive heart failure (n=7 NYHA III or IV) or atrial fibrillation (n=1). Detachable Double-Helix coils designed of two identical strains of stainless steel wire (0.052 inches) with polyester anchored were produced in various diameters (10, 11, 12, 14, 16 mm) were. Prior to the coil embolization an angiography of descending aorta was performed to classify the PDA morphologic (classification of Krichenko), to measure the PDA minimal and ampulla diameter and to define the shunt-grade. The shunt-ratio was calculated using Fick-method. The PDA was catheterized in a retrograde manner and a 7 F Mullins sheet was placed through the PDA into the descending aorta. A Double-Helix coil with loop diameter greater two times the PDA minimal diameter was implanted. 10 minutes after coil embolization calculation of the shunt-ratio and the angiography was repeated. In all dogs a single coil was employed regardless of residual shunting. Clinical and echocardiographic reexaminations were performed within three days after the intervention. M-mode measurements were indexed to body weight by allometric scaling. Data prior and after intervention were compared by student t-test.
German shepherd dogs (n=4) were overrepresented. The median age was 9.2 month (range 4.3-82.0). The median body weight was 24.0 kg (range 8.1-36.0). The PDA was long and conical (Type E) in seven dogs and showed two constriction (Type D) in three dogs. The minimal PDA diameter on the pulmonic site was 4.8-6.3 mm (median 5.9 mm) and the width of the ampulla was 9.1-18.9 mm (median 15.1 mm). In 9/10 dogs the implantation of the primary selected coil was successful, in the remaining dog the next coil size has to be used. After coil placement the shunt-ratio decreased significantly (mean ± SD: 3.80±0.97, range 2.4-5.3 to 1.38±0.46, range 1.0-2.3, p < 0.0001, n=10). Complete closure was documented by angiography in one and by echocardiography in three dogs. Despite of incomplete closure in 7/10 dogs the volume overload was reduced in all dogs leading to a significant reduction of the maximal aortic blood flow velocity (2.980±0.703 to 2.160±0.635, p = 0.0016, n=9) and of the index of left ventricular diastolic diameter (2.259±0.398 to 2.025±0,370, p = 0.0023, n=10).
In conclusion, the polyester fibered Double-helix coil has the stiffness to be fixed in a large PDA up to 6.3 mm and produce a reduction of shunt flow.