以二維斑點追蹤心臟超音波評估貓之左心運動

Abstract

二維斑點追蹤心臟超音波利用超音波在心肌細胞內產生的建設性干涉和破壞性干涉的特殊波紋，對心肌進行定位，進一步計算位移和形變量、形變率，比起傳統超音波利用整體容積形變或壓力差為基礎，測量估計心臟整體收縮力，斑點追蹤心臟超音波可以達到局部心臟收縮力的評估。局部心臟收縮力的表現包括形變量和形變率，綜合各個局部心臟收縮力的表現可進一步評估收縮的同步性和異質性。 本篇論文有兩個章節，第一章節以建立二維斑點追蹤超音波應用於臨床上健康貓計算左心運動形變量、形變率、同步性和異質性的範圍為目的，了解生理因子是對於這些數值的影響，以及二維斑點追蹤超音波計算出的局部收縮力和傳統超音波計算出的整體收縮功能的關聯。第二章節應用二維斑點追蹤心臟超音波比較下呼吸道疾病貓和臨床健康貓隻的左心功能改變。 總體來說，二維斑點追蹤心臟超音波計算出的形變指數，同步性和異質性不受到年齡、體重、心跳、血壓影響，但存在性別差異；並且證實臨床健康貓的心肌運動具有跨壁和節段形變量的異質性；二維斑點超音波的形變指數和傳統超音波的功能指數關連性低，顯示心肌局部功能的改變可能受到其他區域的心肌運動代償，因而傳統超音波的整體功能測量敏感性較低。下呼吸道疾病貓隻的左心形變量偏低，顯示左心收縮、舒張功能受到影響，應該是藉由心室間關聯性以外的機制造成。

Two-dimensional speckle tracking echocardiography (2D-STE) applies the special corrugated of constructive interference and destructive interference when ultrasound passes through myocardial tissue to locate myocytes. This modality is able to calculate myocardial deformation, strain and strain rate (SR), synchrony and heterogeneity. This thesis contains two studies. The first study established 2D-STE of strain, SR, synchrony and heterogeneity of clinically normal cats, physiological characteristics might affect the indices derived from 2D-STE were analyzed, and the correlation between 2D-STE and conventional echocardiography were also evaluated. In the second study left ventricular function of clinically normal cats and cats with lower respiratory tract diseases was assessed using 2D-STE. In general, strain, SR, synchrony and heterogeneity derived by 2D-STE were almost not influenced by age, body weight, heart rate and blood pressure, but affected by gender. In clinically healthy cats, segmental and transmural heterogeneity were evidenced in myocardial deformation. The correlation between 2D-STE indices and conventional echocardiography were weak. It is implied that 2D-STE was more sensitive in detection of left ventricular dysfunction. In terms of decreased myocardial strain and SR, mild systolic and diastolic dysfunction was found in cats with lower respiratory tract diseases, and it might be caused by the mechanism other than ventricular interdependence.