Left Atrial Structure When Expert Imaging Makes the Difference. Renewed Interest in Anatomy & Function. Feroze Mahmood MD, FASE Associate Professor

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1 Left Atrial Structure When Expert Imaging Makes the Difference Feroze Mahmood MD, FASE Associate Professor Center enewed Interest in Anatomy & Function Center Once considered a EDUNDANT structure Of no physiological/anatomical importance Advances in Imaging Transesophageal Echocardiography has revealed the Appreciation of the Significance of Function & Anatomy LAA has contractile, secretory and reservoir properties. It is more compliant than rest of the atria. A multi-centre trial to assess whether TEE imaging can be used to EXCLUDE the presence of LAA thrombi in prior to cardioversion for atrial fibrillation with shorter duration of anticoagulation Center

2 TEE and Left Atrial Appendage TEE is considered the GOLD STANDAD for exclusion of LAA Clots Exclusion of an LAA Clot by TEE enables Cardioversion for patients in Atrial Fibrillation without prior four weeks of Anticoagulation educes reoccurrence of atrial fibrillation after cardioversion Center Chest 2005; 128: > 15% of embolic cerebro-vascular events - Clots from LAA Transesophageal Echo provides clinically feasible imaging Spontaneous Echo Contrast/Clots/Abnormalities of Emptying Flow Velocities Left atrial appendage area >6cm 2 (SPAF II trial) Center Left Atrial Appendage Clot Clot High sensitivity High specificity Left Atrial Appendage Common source of embolus Multiplanner interrogation Center Doppler imaging to enhance function

3 Embryology of Left and ight Atrium Center Embryology of Left and ight Atrium Crista Terminalis Pulmonary Veins Septum Venarum Smooth LA Valve of IVC ough LA LAA Thebesian Valve Center Anatomy LAA Located in anterior most aspect of left atrium Extends from the pulmonary trunk to the left upper pulmonary vein emnant of the primitive left atrium In continuity with the left atrium Center

4 Anatomy LAA structure varies considerably Variation in length from cm Volume ranges from ml Orifice is oval 1.1 by 1.7 cm Center C 2008, the Author Journal compilation C 2008, Blackwell Publishing, Inc. DOI: /j x CME ECHO OUNDS Section Editor: Edmund Kenneth Kerut, M.D. Anatomy of the Left Atrial Appendage Edmund Kenneth Kerut, M.D. Departments of Physiology and Pharmacology, Louisiana State University Health Sciences Center, New Orleans, Louisiana and Heart Clinic of Louisiana, Marrero, Louisiana (ECHOCADIOGAPHY, Volume 25, July 2008) Long hook-like true diverticulum Tubular, narrow, Blind cul-de-sac Lies within the pericardium Center Often multi-lobed SPAC Study Meissner I et al. Prevalence of Potential isk Factors for Stroke Assessed by Transesophageal Echocardiography and Carotid Ultrasonography (Stroke Prevention: Assessment of isk in Community) Mayo Clinic Proc 1999;74: Single Lobe: 29.1% Two Lobes: 54% Multiple Lobes: 34% LAA is distensible and enlarges with increased LA volume Clamping of LAA leads to appreciable increase in LA volume Center

5 Distinct pattern of contraction Shortens to a greater extent than the LA during contraction Acts as decompression chamber for LA. LA pressure major determinant of LAA flow. Center Physiology Physiology Ventricular filling creates suction effect and influences emptying of LA and LAA Active contraction more likely than passive emptying. Blood flow in and out of LAA depends on the left ventricular function Center LAA Function - Echocardiography Two-Dimensional Imaging Size PWD Contrast Shape CFD Thrombi Function MP Lobes

6 Transesophageal Echocardiography Preferred Views Mid-Esophageal Four-Chamber Mid-Esophageal Two-Chamber Mid-Esophageal Five Degrees Incremental otation Center Three-Dimensional Imaging Protocol Center

7 Case Presentation Center Seventy year old male for CABG Surgery Spontaneous Echo Contrast? Clot in the LAA Center

8 En-Face View of the Left Atrial Appendage LUPV MV Center Zoom View of the LAA? Clot /? Anatomical Abnormality Center MP to shave off the LAA Wall Bi-Lobed Left Atrial Appendage Center

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