Abstract
Background: Pulmonary arterial wave reflection provides novel information about pulmonary artery hemodynamics in pulmonary hypertension (PH). PH is common in dogs with myxomatous mitral valve disease (MMVD), though research examining the relationship between pulmonary arterial wave reflection and MMVD with PH is lacking.Hypothesis/Objective: This study investigated conventional echocardiographic parameters and pulmonary artery wave reflection parameters before and after mitral valvuloplasty in canine patients with PH due to MMVD. The parameters were backward pressure (Pb), forward pressure (Pf), and the reflection coefficient calculated as the ratio of peak Pb to peak Pf (RC).Animals: The study subjects were 10 client-owned dogs receiving mitral valvuloplasty for MMVD with PH.Methods: Conventional echocardiographic parameters and pulmonary artery wave reflection parameters were measured before and after mitral valvuloplasty. The relationships between pulmonary artery wave reflection parameters and echocardiographic parameters, estimation of pulmonary artery systolic pressure, and right atrium pressure (RAP) gained by catheter in mitral valvuloplasty were also investigated. Post-operative echocardiography and the measurement of pulmonary arterial wave reflection were performed 2 weeks after mitral valvuloplasty.Results: The parameters of normalized left ventricular internal diameter at end-diastole (LVIDDN), E velocity, and the estimation of pulmonary artery systolic pressure were significantly reduced post-operatively compared with baseline measurements (p < 0.05). Post-operative Pb decreased significantly compared with pre-operative measurements (8.8 ± 5.9 to 5.0 ± 3.2 mmHg, p = 0.037) as did RC (0.37 ± 0.15 to 0.22 ± 0.11, p < 0.01). A statistically significant positive correlation existed between wave reflection parameters and RAP, an estimation of pulmonary artery systolic pressure.Conclusions: Results demonstrate that mitral valvuloplasty can be used to treat secondary PH caused by MMVD, resulting in the improvement of post-operative echocardiographic and wave reflection parameters and a decrease in the right afterload. In some patients, some degree of vascular admittance mismatch persisted, despite the improvement of left atrial pressure. This may be indicative of residual pulmonary arterial disease, which may continue to adversely affect interactions between the right ventricle and the vasculature.
Highlights
Myxomatous mitral valve degeneration (MMVD) is the most common heart disease in dogs, with severe MMVD causing congestive heart failure, resulting in death within a year [1, 2]
20% of pulmonary hypertension (PH) cases presented with septal flattening, and 30% had a notch in the pulmonary artery waveform at the initial visit
Two dogs with persistent PH after mitral valvuloplasty (MVP) presented with the flattening of the interventricular septum, tricuspid regurgitation (TR) was mild (TR velocity 3.0 m/s in both PH patient)
Summary
Myxomatous mitral valve degeneration (MMVD) is the most common heart disease in dogs, with severe MMVD causing congestive heart failure, resulting in death within a year [1, 2]. The treatment results of mitral valve reconstruction have improved, the prognosis after MVP is poor in cases with reactive post-capillary-PH in Abbreviations: AcT, acceleration time; ACVIM, American college of veterinary internal medicine; AO, aortic; BSA, body surface area; CTEPH, chronic thromboembolic pulmonary hypertension; ET, ejection time; LVIDDN, normalized left ventricular internal diameter at end-diastole; MMVD, myxomatous mitral valve disease; MPA, main pulmonary artery; MVP, mitral valvuloplasty; LVIDd, left ventricular internal dimension in diastole; P, pressure; PAH, pulmonary artery hypertension; PAP, pulmonary artery pressure; Pb, backward pressure; Pf, forward pressure; PH, pulmonary hypertension; PVR, pulmonary vascular resistance; RAA index, right atrial area index; RAP, right atrium pressure; RC, reflection coefficient; ROC, receiver-operating characteristic; RVEDA index, right ventricular end-diastolic area index; RVOT, right ventricular outflow tract; SD, standard deviation; TR, tricuspid valve regurgitation; U, velocity; WRI, wave reflection indices. The parameters were backward pressure (Pb), forward pressure (Pf), and the reflection coefficient calculated as the ratio of peak Pb to peak Pf (RC).
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