Left atrial rupture secondary to myxomatous mitral valve disease in 11 dogs

Clinical presentation, echocardiographic findings, treatment strategies, and prognosis of dogs with myxomatous mitral valve disease presented with pericardial effusion due to suspected left atrial tear: a retrospective case-control study

INTRODUCTION/OBJECTIVES

Left atrial tear (LAT) is a life-threatening complication in dogs with myxomatous mitral valve disease (MMVD). The study objective was to describe clinical presentation, echocardiographic findings, treatment strategies, and survival in dogs with LAT compared to a control group of dogs with a similar stage of MMVD but no LAT. ANIMALS AND MATERIALS AND METHODS: two-center retrospective case-controlled study including 15 dogs with and 15 dogs without LAT was conducted. Clinical and echocardiographic data were reviewed, and survival information were collected.

RESULTS

Nine dogs in each group were in stage C of MMVD, while the remaining were in stage B2. No differences between groups were found regarding age, body weight, sex, kidney values, and echocardiography-derived cardiac dimensions. Most reported clinical signs associated with LAT included weakness, respiratory signs, and syncope. Treatment varied and was mainly focused on the management of congestive heart failure. Three dogs with LAT received a pericardiocentesis. All 15 dogs with LAT had died of cardiac causes, 5 dogs during the first 7 days after admission. The median survival time for all 15 dogs with LAT was 52 days compared to 336 days in the control group (P=0.103). When excluding 5 dogs with LAT that died during the first 7 days, the median survival increased to 407 days, not different compared to the control group (P=0.549).

CONCLUSIONS

Dogs with MMVD and LAT have a high short-term mortality; however, when surviving the acute phase, the long-term prognosis may not differ from dogs with a similarly advanced degree of MMVD but without LAT.

Surgical treatment for left atrial rupture due to myxomatous mitral valve disease in three dogs: A case report

Introduction

Myxomatous mitral valve degeneration (MMVD) is an acquired heart disease which sometimes result in pulmonary oedema and left atrial rupture. In previous reports, left atrial rupture has been non‐surgically controlled and its prognosis investigated. There is, however, no report concerning surgically treated left atrial rupture with mitral valvuloplasty and follow‐up results.

Objectives

This report aimed to develop a surgical strategy for a case of left atrial rupture caused by MMVD.

Materials and methods

Three dogs were presented at a private hospital for surgical treatment of MMVD. All three dogs had a previous history of left atrial rupture due to MMVD. The left atrium rapture was diagnosed from indicating that characteristics of the drained pericardial effusion consistent with blood. Mitral valvuloplasty was performed in all dogs using an extracorporeal circulation machine, and the surgical procedure was modified according to each case. In cases with severe adhesion between the pericardial and left atrial appendage, suturing of the left atrial appendage was performed strategically. Additionally, in cases with severe hypotension caused by left atrial rupture, cardiopulmonary bypass was started as soon as possible during the surgical procedure.

Discussion and Conclusion

Since the haemodynamics of all dogs had improved, and the owner reported no cardiac‐related clinical signs, all drugs were withdrawn 3 months after surgery. Since left atrial rupture due to MMVD can cause hypotension, cardiopulmonary bypass should be started as soon as possible during the surgical procedure to maintain the blood pressure and suturing of the left atrial appendage should be performed strategically.

Retrospective evaluation of clinical signs, clinical course, and prognosis between dogs with left atrial rupture secondary to myxomatous mitral valve disease and those with neoplastic cardiac tamponade (2015-2019): 70 cases

OBJECTIVE

To describe the clinical signs, clinical course, and prognosis of suspected left atrial rupture (LAR) secondary to myxomatous mitral valve disease (MMVD) in dogs and to compare them with dogs with suspected neoplastic cardiac tamponade (NCT).

DESIGN

Retrospective study from November 2015 to October 2019 SETTING: An out-of-hours Emergency Animal Hospital.

ANIMALS

Twenty-three dogs with LAR secondary to MMVD (LAR group) and 47 dogs with NCT (NCT group).

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The following were the characteristics of the study population (LAR group vs NCT groups) with P < 0.05 as the significance threshold: male sex, 83% vs 66%; median age, 11.9 vs 12.5 years; and median weight, 3.8 vs 6.4 kg (P < 0.001). Chihuahuas and Miniature Dachshunds were overrepresented in the LAR and NCT groups, respectively. Statistically different clinical findings between the 2 groups were as follows (LAR vs NCT): pulmonary edema, 43% vs 0%; pericardial thrombus, 70% vs 6% (P < 0.001); ineffectiveness of pericardiocentesis (whether aspiration of pericardial fluid was successful or not), 58% vs 2% (P < 0.001); mortality rate within 48 hours of visiting hospital, 35% vs 9% (P < 0.01). No significant difference was observed in survival time after discharge between the 2 groups.

CONCLUSIONS

The proportion of dogs with a diagnosis of LAR secondary to MMVD in dogs with cardiac tamponade was higher than the previously reported rate. Furthermore, the frequency of pulmonary edema, ineffectiveness of pericardiocentesis, and short-term mortality rate was higher in the LAR group than in the NCT group.

Left Atrial Mural Thrombosis and Hemopericardium in a Dog with Myxomatous Mitral Valve Disease

A 14-year-old mixed-breed dog with a 2-year history of myxomatous mitral valve disease was examined for collapse and lethargy. At the presentation, pale oral mucous membranes, rapid and weak femoral pulses, and muffled heart sounds with a moderate left apical systolic murmur were revealed. Echocardiographic examination showed pericardial effusion with organized echogenic material originating from the left atrial wall. Tamponade of the right atrium and severe left atrial enlargement were also observed. Multiple views of the left atrium and left auricle allowed to visualize a hyperechoic mass adherent to the endocardium of the left atrial wall. Contrast-enhanced ultrasonography study allowed to rule out active intrapericardial hemorrhages, and echo-guided pericardiocentesis was performed. No recurrence of pericardial effusion was observed, but the dog suddenly died after 10 days. The postmortem examination confirmed multifocal left atrial thrombosis attached to the endomyocardial tears.