Cardiovascular images: pacemaker-lead fracture and excessive coiling in a dog

A seven-year-old male castrated Labrador Retriever presented emergently due to concern for pacemaker malfunction five years after successful transvenous pacemaker implantation to treat partial atrial standstill. On presentation, the dog's pulse rate was 30-50 beats per minute. An electrocardiogram showed no spontaneous atrial activity or paced ventricular activity. Pacemaker interrogation revealed an increased impedance of 7557 ohms, indicating a lead malfunction. Thoracic radiographs confirmed the lead was fractured and had excessive coiling. The transvenous pacing system was turned off, left in place, and an epicardial pacing system was implanted the following day. The dog was discharged with no perioperative complications. The dog eventually required escalated medical therapy for progressive cardiac disease and was euthanized two years after implantation of the replacement pacemaker. This manuscript illustrates a complete lead fracture and excessive lead coiling, which has not previously been detailed in veterinary medicine.

Echocardiographic caudal vena cava measurements in healthy cats and in cats with congestive heart failure and non-cardiac causes of cavitary effusions

BACKGROUND

Echocardiographic indices of the inferior vena cava have been associated with elevated right atrial pressures in humans.

HYPOTHESIS/OBJECTIVES

Describe caudal vena caval (CVC) sonographic dimensions in healthy cats compared to cats with cardiogenic cavitary effusion (CCE), cardiogenic pulmonary edema (CPE), or non-cardiac causes of cavitary effusion (NCE).

ANIMALS

30 healthy control cats and 52 client-owned cats with CCE, CPE, or NCE examined at two university hospitals.

METHODS

Sagittal 2-dimensional (2D) and M-mode CVC dimensions were acquired from the subxiphoid view. Caudal vena cava collapsibility index (CVC-CI) was calculated. Variables were compared between study groups using Kruskal-Wallis and Dunn's Bonferroni testing. Receiver operating characteristic curves were used to assess sensitivity and specificity for diagnostic categories.

RESULTS

Healthy cats had sagittal 2D and M-mode (median, interquartile range) CVC maximal dimensions of 2.4 mm (1.3-4.0) and 3.4 mm (1.5-4.9) and CVC-CI of 52% (45.2-61.8) and 55% (47.8-61.3), respectively. The CVC maximal dimensions in healthy controls were smaller than in cats with cavitary effusions or pulmonary edema (all P<0.05). CVC-CI was different between CCE and NCE (P<0.0001) with cutoffs of CVC-CI ≤38% (2D) or ≤29% (M-mode) being 90.5% and 85.7% sensitive, and 94.4% and 100% specific for diagnosis of CCE, respectively.

CONCLUSIONS AND CLINICAL IMPORTANCE

Caudal vena cava measurements are larger in cats with cavitary effusions and cats with CPE than healthy cats. In cats with cavitary effusion, decreased CVC-CI, ≤38% (2D) or ≤29% (M-mode), was helpful in distinguishing between cardiogenic and noncardiogenic etiology.