Berlin Heart EXCOR sVAD upsizing and exchange technique

The sterile Berlin Heart Exchange Kit includes the following components:

• Berlin Heart EXCOR blood pump (15 ml),
• Berlin Heart Accessory Kit,
• Berlin Heart Drive Tube,
• Berlin Heart connectors and/or extensions (6- to 9-mm connectors in this patient),
• cable ties, and
• a cable tie installation tool.

The surgeons also need the following instruments and materials:

• sterile heavy scissors,
• tubing clamps,
• basins,
• silk ties,
• sterile injectable saline,
• sterile gloves,
• gowns, and
• a sterile drape.

Prior to priming the Berlin Heart EXCOR pump, the adapter tube should be attached to the driving tube connector. Using a dry 60-mL syringe, air should be removed from the air chamber to retract the membrane prior to introduction of the trocar for priming the blood chamber. After full retraction of the membrane, a clamp is placed on the tubing clamp.

The trocar should be prepared by removing the silicone guard and cutting the tie. Then, the trocar is centred and inserted into the de-airing nipple. The obturator is removed, and the de-airing needle is retracted so the tip is just visible in the blood chamber. A silk tie is used to secure the de-airing needle in place. The de-airing tube is attached to the de-airing needle, ensuring the tube is over both barbs. Next, silk is tied in between the barbs.

A 60-ml syringe is filled with sterile injectable saline and attached to the stopcock on the de-airing tube. Saline should be injected slowly into the pump via the de-airing tube to prevent the formation of microbubbles. A plastic filament from the de-airing nipple may be present. If this filament is observed, it should be directed to the outflow valve during saline priming. Once the blood pump is full of saline, the stopcock on the de-airing tube is closed. Then, the pump primer pinches the valves to evacuate extra saline into the empty basin, ensuring the filament has been removed, if one was present.

Once again, the syringe is refilled, and saline is injected slowly into the blood pump chamber via the de-airing tube. The position of the blood pump is manipulated to allow air to exit the blood pump through the outflow valve. The blood pump is then carefully inspected for any residual air, paying particular attention to the valve leaflets. If tiny bubbles of air are present, these residual bubbles should be removed via the outflow valve. Once the pump is fully de-aired, the stopcock on the de-airing tube is closed, and the metal cannula connectors of the blood pump are capped with the plastic pump seal. The tubing clamp and the adapter tube are removed from the driving tube connector and attached to the driving tube, taking care to keep the ends of the driving tube dry. Finally, the metal cannula connectors are kept in a vertical position pointing upwards until the blood pump is ready for use.

The patient remains extubated during the procedure. With the patient under general sedation, the abdominal wall and the original sVAD are prepared and draped. The new Berlin Heart EXCOR pump is brought to the sterile field, and the plastic pump seal is taken off from one side to prime the upsizing extender with saline. Once all team members are ready to exchange the pumps, the cannulas are clamped on the Teflon felt of the tubing, and the device is simultaneously paused. The cannulas are then cut close to the device. A primed outflow extender is connected to the patient’s cannula. Next, the inflow plastic pump seal is removed and an inflow extender is connected and de-aired with saline. Great care is taken to make sure all connections are made with no air bubbles. While the driver is paused during the airless connection, the pump size should be updated on the IKUS console, if necessary.

Once the blood pump is connected to the patient and the cannulas are de-aired, the driver is restarted at the appropriate rate, with the same settings as those used previously for the following parameters:

• systolic pressure,
• diastolic pressure and
• percent of systole.

With commencement of flow, sVAD support is resumed without difficulty. In this patient, the new sVAD provided increased cardiac output compared to the prior sVAD, and the sVAD settings after exchange were the following:

• systolic pressure of 180 mmHg,
• diastolic pressure of -15 with full fill,
• percent systole of 33%, and
• a rate of 80.

These sVAD settings resulted in a cardiac index of 4.1 from the sVAD with full fill and ejection. The patient remained stable throughout the entire procedure. Anticoagulation and antiplatelet management were left the same throughout the entire procedure, with bivalirudin, aspirin and dipyridamole. After the sVAD pumps were exchanged, all tubing connections were secured with zip ties around the extenders and pump line.

Betadine is removed from the baby’s skin, and the cannulas are wrapped with Aquacell Ag Advantage (Convatec, London, United Kingdom) at the skin entrance. Then, Mepilex Border Flex foam dressings (Mölnlycke Health Care, Peachtree Corners, GA, USA) are applied circumferentially in both cranial and caudal directions. Finally, wide stripes of Mepilex are applied under and over the cannulas, and an elastic band is placed around the abdomen to provide additional security.