Left Atrial and Left Atrial Appendage 4D Blood Flow Dynamics in Atrial Fibrillation

Abstract

Background Atrial 4D flow MRI was employed for the characterization of left atrial (LA) and left atrial appendage (LAA) flow dynamics in patients with atrial fibrillation (AF). Methods and Result 4D flow MRI measured in-vivo 3D blood flow velocities in 60 AF patients and 15 controls. Anatomic maps of LA and LAA stasis and velocity were calculated to quantify atrial peak velocity, mean velocity, and stasis (velocities<0.1m/s). In a sub-study with 30 AF patients, 4D flow metrics were compared to Doppler transesophageal echocardiography (TEE). For all 15 controls, LAA mean and peak velocities were consistently lower (by 21%/12%, p<0.001) while LAA stasis was higher (by 58%, p<0.001) compared to the LA. In contrast, lower LAA velocity and increased LAA stasis was only found in a fraction (38 of 60) of AF patients. In AF patients, increased CHA2DS2-VASc score was associated with significantly (p<0.043) reduced LA velocities and elevated stasis. There was a heterogeneous expression of atrial flow dynamics and 25–68% of AF patients demonstrated flow in the normal range: 25%/68% for LA/LAA stasis, 38%/60% for LA/LAA peak velocities. TEE velocities were modestly but significantly (p<0.05) correlated with 4D flow based LA velocities (r=0.41) and stasis (r=−0.39). Conclusions AF resulted in overall impaired but individually variable flow dynamics in both the LA and LAA. AF patients demonstrated atrial flow in the normal range despite elevated CHA2DS2-VASc score.

Computational Fluid Dynamic Analysis of the Left Atrial Appendage to Predict Thrombosis Risk

“…In fact, though transthoracic (TTE) and transoesophageal echocardiography (TEE) are available in the clinic to measure the blood flow velocity in both the LA and the LAA, both techniques can only provide average information on the velocity magnitude and direction in the sampling volume, without being able to give detailed spatial 3D information on the local flow conditions (30, 31). Ideally, 4D flow MR could provide similar information as the CFD analysis, but the spatial resolution, typically larger than 1 mm voxel, is not sufficient to assess a small region such as the LAA, and is thus not yet suitable for clinical applications (32). …”

Spatial phenotyping of the endocardial endothelium as a function of intracardiac hemodynamic shear stress

“…For human MRI, IRB approval and informed consent were obtained from all 4D flow MRI study participants. The specifics of image acquisition and analysis were as previously described (Markl et al, 2012, 2016). Studies were performed on 8 healthy volunteers (mean age: 24±1.8 years; four females and four males, heart rate 63.5±beats per minute, LV ejection fraction (EF) % 65.3±2.1).…”

4D Flow MR Imaging Reveals a Decrease of Left Atrial Blood Flow in a Patient with Cardioembolic Cerebral Infarction after Pulmonary Left Upper Lobectomy

“…12 4D flow MRI evaluation of left atrial (LA) hemodynamics has been reported. [13][14][15] Some of regions: the junction between the LA and each of the four PVs (LA-PV), and the LSPV stump. The average blood flow velocity during one cardiac cycle was measured in each VOI.…”