Читать книгу Interventional Cardiology - Группа авторов - Страница 105

Lesions at the ostium or mid segment of the LMS are often best seen in the cranial anteroposterior (AP) (cranial 40°) or left (LAO, 30–50° left; 25–40° cranial) views. A straight AP view with only slight rightward angulation to project the catheter tip off the spine is sometimes advocated but may not be optimal because the ostium of the LMS can be projected over the left coronary sinus. The ostium of the LMS is also covered by the coronary sinus in a LAO caudal view (30–50° left; 25–40° caudal), the so‐called “spider view”, which is ideal to demonstrate the mid LMS and the LMS bifurcation. In this view the picture can be grainy and of poor quality particularly when angulation is steep and in obese patients; the image can be optimized by positioning the LMS in the center of the field and reducing the inhomogeneity induced by the presence of the lung by blanking the field from the 12 o’clock to the 3 o’clock position. If renal function allows it, a small test injection before acquisition is sensible because a more horizontal axis of the heart can require steeper caudal angulation and occasionally overlap at the LMS bifurcation can be separated by rotating more steeply to the left or toward AP caudal.