Tooye on the 24-hour monitor

 

Maud van de Stadt, ex-FAB scholar at Langford, reports on a case she saw there in 2000

TOOYE, A FOUR-and-a-half-year­old neutered male domestic shorthaired cat, was referred to the Feline Centre in July 2000 because he kept fainting. He was having several fainting episodes a day, during which he collapsed and was flat out for about four seconds. He then shook his head and immediately recovered.

 

Blood tests showed no abnormalities and tests for feline immunodeficiency virus (FIV) and feline leukaemia virus (FeLV) were negative. ECG and blood pressure measurements also showed no abnormalities, even when measured straight after a fainting episode. Radiographs of the chest and abdomen showed nothing significant. However, ultrasonography revealed that the ventricles of the heart were not beating sometimes when they should have done. An ECG trace made at the same time confirmed this. However, because Tooye was under a general anaesthetic when he was ultrasounded we were not sure whether this was the cause of his fainting when he was awake!

I asked the help of Langford's lecturer in cardiology, Dr Luca Ferasin. We decided to try Tooye on an ECG monitor which would record Tooye's heart activity constantly for 24 hours and would hopefully be able to tell us whether Tooye's heart had stopped beating and, if so, when it had happened. It was the first time the monitor had been used for cats at Langford.

The monitor consists of a tape recorder and ECG leads which are connected to the animal. Dogs carry the tape recorder around attached to their bodies, but it is too heavy for cats to do the same. We decided to try and leave the tape recorder in the kennel, attached to Tooye. The leads were covered with tape, to prevent Tooye from biting through them and the electrodes on his skin were covered with a bandage. Tooye was fantastic! He coped very well with the machinery attached to him and a perfect 24 hour tape was recorded. The tape was then sent to Karen Langford at a hospital in Taunton where it was converted into a proper ECG.

The tape confirmed what we had been fearing. At some stages the ECG trace showed no activity, indicating that the heart had stopped beating for a short episode (frequent prolonged episodes of complete atrioventricular block with ventricular standstill). During such an episode the outflow of blood from the heart to the rest of the body is minimal and the animal will faint. No medication can do anything to prevent this and the risk of sudden death in one of these episodes is significant.

Tooye's only chance of cure would be to place a pacemaker in the heart. When the heart stops beating the pacemaker notices and quickly gives a little stimulus which makes the heart start beating again. The pacemaker would start Tooye's heart going again, preventing him from fainting. But where to get a cat pacemaker?

The pacemaker

Again Karen Langford helped. She came to the Feline Centre with a paediatric (child's) pacemaker and helped to programme it while Mr Hotston Moore, Langford's lecturer in soft tissue surgery, and Luca were performing the surgery. The pacemaker itself was put in under the skin, just behind Tooye's elbow and a lead went through one of the big heart vessels into the heart. The tip of the lead sends information through to the

pacemaker, which can respond when necessary by sending back a stimulus to the heart and making it contract.

Tooye recovered from the surgery and coped well with his implanted pacemaker. He was discharged and was reported to be doing very well. No more episodes of fainting were seen by his owners and Tooye was enjoying being outside in his beautiful garden.

Sadly Tooye did develop complications. A few months after surgery his owners noticed that Tooye's breathing was becoming laboured. Tooye returned to Langford where he was diagnosed with a chylothorax (accumulation of lymphatic fluid in the chest) Chylothorax is seen in people with pacemakers and is likely to be caused by irritation by the pacemaker leads. Because of the volume of fluid in the chest it is hard for the animals to breath properly and they get very breathless (dyspnoeic). Sometimes the fluid dries out by itself, but sometimes removal of the cause (in this case the pacemaker) is necessary. The fluid was drained and Tooye immediately breathed much more easily. However the fluid built up again over the next few weeks and required further drainage. The fluid came back after each drainage, despite several courses of medication with drugs used in people with the same complication. Removal of the pacemaker could possibly stop the fluid but would cause the fainting again, with all its risks. It was a very difficult dilemma.

Tooye needed his chest drained more and more frequently and started to lose his appetite, raising the question whether it was right to continue treatment. His owners felt that Tooye's quality of life was deteriorating and decided that he should be put to sleep as there were concerns that more surgery to remove the pacemaker, although removing the fluid accumulation problem, would not cure his heart problem. He was put to sleep five-and-a-half months after the pacemaker was implanted.

Although this is sad ending, it was a case from which we all learned so much and hope to be able to use the information in the future to benefit other cats. I would like to thank the referring vets and would like to dedicate this article to brave Tooye and his lovely and understanding owners.