Abnormal Myocardial Blood Flow Reserve Observed in Cardiac Amyloidosis

Abstract

We performed real-time myocardial contrast echocardiography on a patient with cardiac amyloidosis and previous normal coronary angiography presenting with atypical chest pain to assess myocardial blood flow reserve (MBFR). Myocardial contrast echocardiography was performed and flash microbubble destruction and replenishment analysis was used to calculate myocardial blood flow. Dipyridamole was used to achieve hyperemia. MBFR was derived from the ratio of peak myocardial blood flow at hyperemia and rest. The results show a marked reduction in MBFR in our patient. Previous reports of luminal obstruction of intramyocardial rather than epicardial vessels by amyloid deposition may be causing microvascular dysfunction.

Keywords: Cardiac amyloidosis; Contrast echocardiography; Echocardiography; Myocardial blood flow; Myocardial blood flow reserve.

Figures

Fig. 1. Cardiac MR four chamber view showing biatrial and biventricular subendocardial delayed enhancement in keeping with a diagnosis of cardiac amyloidosis.

Fig. 2. Replenishment curves following bubble destruction using high amplitude ultrasound pulse at rest (A) and post-dipyridamole (stress) (B). A normal study curve has also been plotted for comparison, taken from previous published data by our group. Peak video intensity A is proportional to and therefore representative of blood volume. Gradient β (dB/s) represents peak blood velocity.

Fig. 3. Real-time myocardial contrast echo images showing bubble replenishment at rest and stress with a normal study for comparison. Each number in top left of image represents number of frames post bubble destruction. Notice bubble replenishment is more rapid and homogenous in the normal study compared to our patient both at rest and stress.