Which techniques do exist?

There are three different techniques available:

• Surgical ligation

• Transarterial closure (keyhole technique)

• Transvenous closure (keyhole technique)

Which technique is best?

There is no best technique for PDA closure. The techniques have just different advantages and disadvantages. Surgery is obviously ways more invasive compared to the keyhole techniques. Especially with large PDA vessels it also carries the risk of rupturing the vessel which is then often fatal. Using keyhole techniques the PDA can be approach via the arteries or via the veins. The arterial approach is often technically easier. However, there are limitations to the patient size. Small patients often don't have large enough arteries to feed the device. Veins dilate much easier than arteries. The transvenous approach which we predominantly use at SCVS allows therefore also closure in very small patients. Dogs as small as 1kg have been treated at SCVS.

For the transarterial closure the Amplatz-Canine-Duct-Occluder (ACDO) device is usually used. The transvenous approach requires using an alternative device, the Amplatz-Vascular-Plug-II (AVP-II). This device has a slightly different design compared to the ACDO to allow the transvenous approach, but the function is otherwise identical and there appears to be no difference in closure rates.

Surgical ligation:
For surgical ligation the chest needs to be opened. The duct will then be identified and closed from the outside using a ligature.

Transarterial closure:
An incision is made in the groin area to identify the femoral artery which is supplying the hind leg with blood. The artery is then punctured and catheters are inserted. The catheters are then advanced towards the heart and the ACDO device is positioned in the PDA vessel following a contrast study which allow to visualise and measure the duct. Following successful closure of the PDA, the femoral artery usually needs to get ligated before closing the skin wound.

Transvenous closure:
The femoral vein is punctured percuntaneously. Catheters are then advanced towards the heart and towards the PDA vessel. Similar to the transarterial closure, a contrast study is needed before the device can be positioned to close the PDA. Following successful closure, patients only get a pressure bandage for 8-12h to avoid bleeding and bruising and most patients will be discharged the following day.