Complications of a permanent transvenous pacing catheter in a horse.

This research article describes the post-mortem findings of a 9-year-old horse fitted with transvenous pacing cardiac catheters, revealing severe complications including thrombi, bacterial colonies, and suppurative endocarditis.

Study Description and Objective

The study focuses on gross and histopathological findings observed in a 9-year-old horse that had two permanent transvenous cardiac pacing catheters installed 18 and 34 months before it died. The primary objective of the research was to explore and describe the complications arising from the implantation of these catheters, and compare these results with similar findings in humans and other animals with like implants.

Observations and Findings

• The research observed extensive fibrino-haemorrhagic thrombi, or blood clots involving fibrin and red blood cells and large numbers of bacterial colonies. These were conspicuously present along the installed catheter wires, and on surfaces of the right heart, including walls and valves.
• Endocarditis, inflammation of the internal tissues of the heart, particularly severe around the atrial electrode’s attachment area, was noted. The atrial electrode was found loosely attached to the endocardium, the innermost lining of the heart, by a thin band of tissue.
• The ventricular electrode, on the other hand, was embedded firmly in the myocardium, the middle layer of the heart wall, and was surrounded by a dense area of fibrous connective tissue. Within this tissue, multifocal mineralized areas were visible, showing signs of calcification or abnormal hardening.
• On the microscopic level, there were indications of terminal bacteraemia – the presence of bacteria in the blood, typically a sign of serious infection.

Comparison with Other Cases

The researchers discuss the findings drawn from this study in the context of similar observations made in human cases and other animals fitted with cardiac implants. This provides a broader perspective on the potential complications resulting from permanent cardiac implant procedures and offers a comparative analysis that may guide improvements in surgical and post-operative management strategies.