Combined double chambered right ventricle, tricuspid valve dysplasia, ventricular septal defect, and subaortic stenosis in a dog

Retrospective evaluation of notched and fragmented QRS complex in dogs with naturally occurring myxomatous mitral valve disease

Myxomatous mitral valve disease (MMVD) is the most common cardiac disease in dogs. The association of QRS notching (nQRS) or fragmentation (fQRS) with disease severity is currently unknown. The study objective was to assess the prevalence of nQRS and fQRS in dogs with MMVD and its severity according to ACVIM classification and to compare the results with a group of healthy dogs. This retrospective cross-sectional study included 34 healthy control dogs and 155 dogs with spontaneous MMVD (42% of dogs in class B1, 23% in class B2 and 35% in class C). fQRS was defined as nQRS complexes in two contiguous leads in the frontal plane (leads I and aVL) and (II, III or aVF). A one-way ANOVA with Bonferroni post-hoc test was used to assess the differences in continuous data between control and MMVD groups. Of the MMVD group, 58% showed nQRS in at least one lead and 27% presented fQRS. There was no difference between the number of leads with a nQRS and disease severity (p = 0.75) nor did the number of leads with a nQRS correlate with left atrial size (r = 0.48; p = 0.5). The number of dogs with fQRS did not differ among classes of MMVD (p = 0.21). nQRS and fQRS were more prevalent in dogs with MMVD compared to control dogs (p < 0.01). This study did not identify any relationship between the number of leads with a nQRS and disease severity. However, dogs with MMVD had a higher prevalence of nQRS and fQRS compared to control group.

Long-term relief of obstruction in a dog with double-chambered right ventricle using combined cutting balloon and high-pressure balloon dilation

A 4-month-old intact female Golden Retriever dog was diagnosed with double-chambered right ventricle (DCRV) without infundibular stenosis, tricuspid valve dysplasia, and subsequent severe right atrial enlargement and was referred for combined cutting balloon and high-pressure balloon dilation. On presentation, these diagnoses were confirmed, and the peak systolic pressure gradient across the DCRV obstructive lesion assessed by continuous wave Doppler interrogation was 80 mm Hg. The obstructive lesion within the mid-right ventricle had a diameter of 6 mm through which blood flowed from the proximal right ventricular (RV) chamber to the distal RV chamber. The following day, general anesthesia was induced, and a minimally invasive balloon dilation was performed. A cutting balloon was inflated across the mid-RV obstructive lesion, followed by an inflation of a high-pressure balloon across this lesion. The high-pressure balloon catheter that was used had a diameter roughly 1.5 times the diameter of the pulmonary annulus. The following day, echocardiographic evaluation of the patient revealed a peak systolic pressure gradient across the DCRV obstructive lesion of 16 mm Hg, with a RV diameter at the level of obstruction of 11 mm. Twelve months later, the dog remains asymptomatic, right atrial size has decreased, and has a peak systolic pressure gradient across the DCRV lesion of 20 mm Hg.