慢性退行性房室瓣疾病患犬之都卜勒超音波腎臟 血流指數與以Enalapril治療後之變化

Abstract

慢性退行性房室瓣疾病是造成犬心衰竭最常見的原因。血管張力素轉化酶抑 制劑，如enalapril，可有效緩解心衰竭犬隻的臨床症狀。然而，當犬隻因鬱血性心 衰竭導致腎臟灌流量降低時，使用血管張力素轉化酶抑制劑反而會危害腎臟功能。 都卜勒超音波是一種非侵入性的診斷技術，它可藉由計算腎臟血流指數—脈動指 數及阻抗指數，來評估血管阻力。本研究目的是評估罹患慢性退行性房室瓣疾病 的犬隻，其腎臟血管阻力的改變，並監測患犬使用enalapril 治療後，對於腎臟血 管阻力的影響。共蒐集二十六隻罹患慢性退行性房室瓣疾病患犬及三十六隻健康 犬隻。大部分犬隻都接受生理學檢查、實驗室檢查、胸腔放射線學檢查、心電圖 檢查、心臟及腎臟的超音波學檢查。其中十二隻患犬分為兩組，接受不同藥物劑 量的治療。組別一使用enalapril 0.5 mg/kg，一天一次，連續使用四周，於一個月 後複診。組別二使用enalapril 0.5 mg/kg，一天兩次，連續使用四周，每周複診。 結果腎臟血流指數與年齡、血球容積比、血中尿素氮、肌酸酐、心臟搏出分率或 短縮分率之間都沒有發現相關性。在心臟病組的平均動脈壓與脈動指數及阻抗指 數則呈現極顯著的負相關性(p<0.01, 脈動指數：r2=0.381；阻抗指數：r2=0.410)。 心臟病組的脈動指數及阻抗指數都較對照組來的高，但均未達到統計學上的顯著 差異。然而，與心衰竭嚴重程度之間卻有明顯的正向趨勢存在。另一方面，組別 一的腎臟血流指數在使用enalapril 治療一個月後，呈顯著上升。脈動指數與阻抗 指數分別從1.08±0.18 和0.63±0.04 上升到1.32±0.25 和0.69±0.05(p<0.05)。組別二 的腎臟血流指數也在治療後，呈現顯著上升。脈動指數與阻抗指數分別從1.30±0.21 和0.69±0.05 上升到1.80±0.30 和0.79±0.04(p<0.05)。總結本研究，心臟病犬的腎臟 血流指數與血壓及左心室舒張功能具有相關性。我們的結果顯示，慢性退行性房 室瓣疾病患犬的腎臟血管阻力與心衰竭嚴重程度之間有正向的相關趨勢。同時也 證明了enalapril 會促使慢性退行性房室瓣疾病患犬的腎臟血管阻力上升。因此， 脈動指數與阻抗指數或許可以在慢性退行性房室瓣疾病患犬的臨床治療上，提供 臨床獸醫師關於腎臟血液動力學的變化訊息。

Chronic degenerative atrioventricular valvular disease (CDAVD) is the most common cause of heart failure in the dog. Angiotensin-converting-enzyme inhibitors (ACEI), such as enalapril, have been found to be useful in the management and alleviation of clinical signs related to heart failure in dogs. However, ACEI may depress renal function in patients with severe congestive heart failure due to a further decrease in renal perfusion. Doppler ultrasound is a non-invasive technique that can be used to estimate vascular resistance by the calculation of pulsatility and resistive indices (PI and RI). The indices have been found to be correlative with vascular changes in renal diseases. The aims of this study were to examine renal vascular resistance changes in dogs with CDAVD and to evaluate the influence of renal impedance after enalapril treatment in these dogs. Twenty-six dogs with CDAVD and thirty-six healthy dogs were included in this study. Physical examination, laboratory examination, thoracic radiography, electrocardiogram, cardiac and renal ultrasound were performed on most dogs. Twelve dogs with CDAVD were divided into two groups undergoing different treatment protocol. Group 1 was prescribed enalapril (0.5 mg/kg, sid) for 4 weeks and evaluated one month later. The other group was prescribed enalapril (0.5 mg/kg, bid) for 4 weeks and evaluated weekly. No correlation was found between the renal indices and age, packed cell volume, blood urea nitrogen, creatinine, ejection fraction, or fractional shortening in the subjects in our study. However, a significant negative correlation was found between the indices and mean blood pressure in dogs with CDAVD (p<0.01, PI: r2=0.381; RI: r2=0.405). The mean PI and RI values in dogs with CDAVD were higher than that in normal animals but didn't reach significant levels. Nevertheless, there was a significant effect attributable to the degree of heart failure. On the other hand, there was a significant increase in the renal indices after administration of enalapril of group 1. Mean PI and RI values significantly increased from 1.08±0.18 and 0.63±0.04 to 1.32±0.25 and 0.69±0.05 (p<0.05). In the group 2, the indices were also significantly higher than before the treatment, too. The mean PI and RI values significantly increased from 1.30±0.21 and 0.69±0.05 to 1.80±0.30 and 0.79±0.04 (p<0.05). It is concluded that there are correlations between renal indices and blood pressure or left ventricular diastolic function in dogs with CDAVD in the present study. Our results suggest a positive correlation between renal vascular resistance and the severity of heart failure in dogs. In this study, we demonstrated that enalapril promoted the increase of renovascular resistance in dogs with CDAVD. Therefore, the PI and RI may provide information to the veterinary clinicians when monitoring renal hemodynamic in dogs with CDAVD undergoing treatment.