Successful treatment of pacemaker-induced stricture and thrombosis of the cranial vena cava in two dogs by use of anticoagulants and balloon venoplasty.
METHODS
2 castrated male Labrador Retrievers (dogs 1 and 2) were evaluated 3 to 4 years after placement of a permanent pacemaker. Dog 1 was evaluated because of a large volume of chylous pleural effusion. Dog 2 was admitted for elective replacement of a pacemaker.


RESULTS
Dog 1 had mild facial swelling and a rapidly recurring pleural effusion. Previously detected third-degree atrioventricular block had resolved. Cranial vena cava (CVC) syndrome secondary to pacemaker-induced thrombosis and stricture of the CVC was diagnosed on the basis of results of ultrasonography, computed tomography, and venous angiography. Dog 2 had persistent third-degree atrioventricular block. Intraluminal caval stricture and thrombosis were diagnosed at the time of pacemaker replacement. Radiographic evidence of pleural effusion consistent with CVC syndrome also was detected at that time.


RESULTS
Dog 1 improved after treatment with unfractionated heparin and a local infusion of recombinant tissue-plasminogen activator. Balloon venoplasty was performed subsequently to relieve the persistent caval stricture. In dog 2, balloon dilatation of the caval stricture was necessary to allow for placement of a new pacing lead. Long-term anticoagulant treatment was initiated in both dogs. Long-term (> 6 months) resolution of clinical signs was achieved in both dogs.


CONCLUSIONS
Thrombosis and stricture of the CVC are possible complications of a permanent pacemaker in dogs. Findings suggested that balloon venoplasty and anticoagulation administration with or without thrombolytic treatment can be effective in the treatment of dogs with pacemaker-induced CVC syndrome.
Cunningham
Suzanne M
SM
Department of Clinical Sciences, Cummings School of Veterinary Medicine, Tufts University, North Grafton, MA 01536, USA. suzanne.cunningham@tufts.edu
Ames
Marisa K
MK
Rush
John E
JE
Rozanski
Elizabeth A
EA
D000800:Angioplasty, Balloon / Q000662:veterinary*; D000818:Animals; D000925:Anticoagulants / Q000627:therapeutic use*; D003251:Constriction, Pathologic / Q000209:etiology / Q000628:therapy / Q000662:veterinary*; D004283:Dog Diseases / Q000628:therapy*; D004285:Dogs; D006493:Heparin / Q000627:therapeutic use; D008297:Male; D010138:Pacemaker, Artificial / Q000009:adverse effects / Q000662:veterinary*; D013927:Thrombosis / Q000209:etiology / Q000628:therapy / Q000662:veterinary*; D010959:Tissue Plasminogen Activator / Q000627:therapeutic use; D014683:Vena Cava, Superior / Q000473:pathology
D000925:Anticoagulants; D006493:Heparin; D010959:Tissue Plasminogen Activator