First-in-Man 4-Chamber Pressure-Volume Analysis During Transcatheter Aortic Valve Replacement for Bicuspid Aortic Valve Disease.

This report constitutes a first-in-man description of pressure-volume analysis in all 4 cardiac chambers before and after transcatheter aortic valve replacement. Pressure-volume analysis demonstrated that the hemodynamic consequences of valve replacement are chamber-specific and influenced by all aspects of the procedure (i.e., rapid ventricular pacing), not just valve deployment. (Level of Difficulty: Advanced.).

Blood Flow Dynamics in a Giant Left Atrial Appendage Aneurysm Visualized by 4D-Flow CMR.

Aneurysms of the left atrial appendage (LAA) are rare entities that often require surgical intervention. We demonstrate multimodality imaging features of a giant LAA aneurysm, with a focus on 3-dimensional blood flow dynamics by using 4-dimensional-flow cardiac magnetic resonance. (Level of Difficulty: Advanced.).

Impact of aortic stiffness by velocity-encoded magnetic resonance imaging on late gadolinium enhancement to predict cardiovascular events.

BACKGROUND: Increased aortic stiffness has been established as a marker in various cardiovascular diseases. Previous reports revealed a significant correlation between aortic stiffness and myocardial scarring using the late gadolinium enhancement cardiovascular magnetic resonance (LGE-CMR). However, prognostic data concerning aortic stiffness combining myocardial scarring remains limited. METHOD: A total of 402 patients who had undergone clinical CMR for the evaluation of cardiac function, LGE, and aortic pulse wave velocity (PWV) using velocity encoded-CMR (VE-CMR) were included. Patients were classified into 4 groups using mean PWV and the presence of LGE as elevated or non-elevated PWV and positive or negative LGE. Patients received follow-up for major adverse cardiovascular events (MACE) comprising cardiovascular death, non-fatal myocardial infarction, hospitalization for heart failure, coronary revascularization, and ischemic stroke. Predictors of MACE and hard cardiac events (cardiovascular death or non-fatal myocardial infarction) were evaluated. RESULTS: During the average follow-up period of 47.7 months, 58 MACE occurred. Patients who had elevated PWV and positive LGE experienced the highest rate of MACE compared to the group with non-elevated PWV and negative LGE (HR 11.90, p < 0.001). Among patients who had LGE, those who had elevated PWV experienced a 2.4-times higher rate of MACE compared to those who had non-elevated PWV. Multivariate analysis showed that PWV and LGE were independent predictors of MACE and hard cardiac events. PWV had excellent intra- and inter-observer reproducibility (intra-: ICC = 0.98, p < 0.001, inter-: ICC = 0.97, p < 0.001). CONCLUSION: Aortic stiffness using VE-CMR had prognostic value to predict cardiovascular events, with the added benefits of LGE.

Cardioform Septal Occluder in the Management of Cardiac Tamponade as a Complication of LAA Closure.

Cardiac tamponade is a life-threatening complication during left atrial appendage (LAA) closure. We report a 77-year-old woman who underwent a transseptal puncture for LAA closure with the Watchman device that was complicated by tamponade. This was successfully treated with the deployment of a Cardioform 25-mm septal occluder device. (Level of Difficulty: Intermediate.).

Catheter-Based Cardio-Neural Ablation for Refractory Vasovagal Syncope: First U.S. Report.

We highlight the feasibility and efficacy of a new application for catheter ablation to target atrial ganglionated plexi in a patient with refractory vasovagal syncope. We describe a physiologically guided technique and demonstrate 18-month freedom from syncope with 2 tilt-table tests to objectively assess reproducible elimination of symptomatology and underlying pathophysiology. (Level of Difficulty: Beginner.).

Left atrial appendage morphology and silent cerebral ischemia in patients with atrial fibrillation.

BACKGROUND: Left atrial appendage (LAA) is the major source of cardiac thrombi in atrial fibrillation (AF) and plays a major role in cardioembolic events. OBJECTIVE: To investigate the correlation between LAA morphology and the burden of silent cerebral ischemia (SCI) as a new thromboembolic risk marker in patients with AF. METHODS: A total of 348 patients with AF undergoing transcatheter ablation were enrolled. A cerebral magnetic resonance (MR) was performed to assess SCI burden, while LAA morphology was studied by MR or computed tomography and categorized as follows: cactus in 52 (14.9%) patients, chicken wing in 177 (50.9%), wind sock in 101 (29.0%), and cauliflower in 18 (5.2%). RESULTS: SCIs were detected in 295 (84.8%) patients, with a median number of lesions of 23. SCI burden was related to LAA complexity: 30.8% and 17.3% patients with cactus, 30.5% and 22.0% with chicken wing, 13.9% and 27.7% with wind sock, and 16.7% and 38.9% with cauliflower LAA morphologies were in the first and fourth quartiles of number of SCI per patient, respectively (P = .035). After adjustment for potential confounders, only age (ß 0.12; 95% CI 0.08-0.16; P < .001), chicken wing (ß -0.28; 95% CI -0.51 to -0.04; P = .021), wind sock (ß 0.38; 95% CI 0.12-0.65; P = .005), and cauliflower (ß 0.61; 95% CI 0.07-1.14; P = .026) LAA morphologies were significantly related to SCI burden. CONCLUSION: LAA morphology relates to the burden of SCI in AF patients. Future research should corroborate if accessible methods (eg, echocardiography) are able to describe LAA morphology, permitting its use within universal thromboembolic risk predictors in AF patients.

Symptomatic pulmonary hypertension with giant left atrial v waves after surgical maze procedures: evaluation by comprehensive hemodynamic catheterization.

BACKGROUND: The surgical maze procedure is highly effective in treating symptomatic atrial fibrillation but may have detrimental effects on left atrial (LA) contractile function and compliance. OBJECTIVE: To describe a series of patients presenting with symptomatic pulmonary hypertension due in part to LA dysfunction after surgical maze procedures. METHODS: This report includes 9 patients who (1) presented to Mayo Clinic (Rochester, MN) between 2008 and 2012 with unexplained dyspnea and pulmonary hypertension after the surgical maze procedure, (2) underwent comprehensive hemodynamic catheterization with transseptal measurement of LA pressure, (3) had large v waves on LA pressure waveforms, and (4) did not have significant mitral valve regurgitation or stenosis or pulmonary vein stenosis. RESULTS: Invasive hemodynamic assessment revealed (1) severe pulmonary hypertension (mean pulmonary pressure 47 ± 6 mm Hg), (2) severe LA hypertension (27 ± 4 mm Hg), (3) giant LA v waves (to 50 ± 8 mm Hg), (4) absence of LA or left ventricular a waves, and (5) blunted x descents (2 ± 1 mm Hg). Left ventricular end-diastolic pressure was also elevated (20 ± 5 mm Hg). CONCLUSIONS: Abnormalities in LA compliance and contractility may lead to giant LA v waves and symptomatic pulmonary hypertension after surgical maze procedures. This syndrome should be considered in the differential diagnosis for pulmonary hypertension and underscores the importance of comprehensive hemodynamic catheterization.

Intrinsic left atrial histoanatomy as the basis for reentrant excitation causing atrial fibrillation/flutter in rats.

BACKGROUND: Although the pulmonary veins are accepted as preferential trigger sites for paroxysmal atrial fibrillation/flutter (AF/AFL), the intrinsic basis for reentrant excitation is undetermined in persistent AF/AFL. OBJECTIVE: To identify histoanatomic substrates for reentrant AF/AFL in rats. METHODS: Spatiotemporal patterns of impulse propagation were visualized optically on the posterior surface of the atria in di-4-ANEPPS-stained Langendorff-perfused rat heart/lung preparations. The relevant histology was also analyzed. RESULTS: Burst (S1-S2) pacing at the right atrium provoked AF/AFL in 15 of 19 hearts, and most cases developed by organized reentrant excitation through the coronary sinus (CS) and left atrial (LA) roof, with nonorganized irregular propagation in 3 cases. The reentrant circuit developed along 2 pathways of propagation: a slower pathway at the LA roof (conduction velocity, 42.4 ± 16.6 cm/s) and a faster pathway along the CS (conduction velocity, 53.3 ± 9.2 cm/s). Upon extra stimulus (S2) after consecutive S1 pacing, the impulse at the roof propagated retrogradely from the CS, resulting in reentrant propagation anchored by the atrial septum and posterior LA. Histologic quantification revealed significantly lower myocardial density in the posterior LA and the septum than elsewhere in the atria. Moreover, myocytes in the LA roof, than in the CS, were of lower density, more randomly arranged in the direction of conduction, and characterized by more disorganized distribution of connexin 43 over the entire cell membrane, which is consistent with the slower impulse propagation there. CONCLUSION: The intrinsic histoanatomic heterogeneity in the LA would constitute a pro-reentrant substrate responsible for perpetuating AF/AFL.

Catheter ablation of atrial fibrillation supported by novel nonfluoroscopic 4D navigation technology.

BACKGROUND: The MediGuide technology (MGT) represents a novel sensor-based electromagnetic 4-dimensional (4D) navigation system allowing real-time catheter tracking in the environment of prerecorded X-ray loops. OBJECTIVE: To report on our clinical experience in atrial fibrillation (AF) ablation with recently available MGT-enabled ablation catheters. METHODS: The MGT was used in addition to a conventional 3D mapping system in 80 patients with AF (age 61 ± 10 years; 47 men; 40 with persistent AF), who underwent circumferential pulmonary vein isolation and voltage mapping with and without substrate modification. Short native right anterior oblique/left anterior oblique loops were used as background movies for the nonfluoroscopic placement of sensor-equipped diagnostic catheters into the coronary sinus and the right ventricle. After single transseptal puncture, selective angiograms of the pulmonary veins were used as background movies for near nonfluoroscopic left atrial reconstruction. Computed tomography registration as well as mapping/ablation was performed by using the new open-irrigated MGT-enabled ablation catheter. RESULTS: MGT application was not associated with a change in established workflow. Large parts of the procedure (mean entire duration 167 ± 47 minutes) could be done without additional fluoroscopy, whereas median residual fluoroscopy duration of 4.6 (interquartile range: 2.9, 7.1) minutes was mainly used for the acquisition of background loops, transseptal puncture, occasional verification of transseptal sheath position, and manipulation of the circular mapping catheter. Three (4%) minor complications occurred. CONCLUSIONS: The MGT integrates easily into the workflow of standard AF ablation and allows for high-quality nonfluoroscopic 4D catheter tracking. This results in low radiation exposure for patients and staff without complicating the workflow of the procedure.

Automated analysis of atrial late gadolinium enhancement imaging that correlates with endocardial voltage and clinical outcomes: a 2-center study.

BACKGROUND: For late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR) assessment of atrial scar to guide management and targeting of ablation in atrial fibrillation (AF), an objective, reproducible method of identifying atrial scar is required. OBJECTIVE: To describe an automated method for operator-independent quantification of LGE that correlates with colocated endocardial voltage and clinical outcomes. METHODS: LGE CMR imaging was performed at 2 centers, before and 3 months after pulmonary vein isolation for paroxysmal AF (n = 50). A left atrial (LA) surface scar map was constructed by using automated software, expressing intensity as multiples of standard deviation (SD) above blood pool mean. Twenty-one patients underwent endocardial voltage mapping at the time of pulmonary vein isolation (11 were redo procedures). Scar maps and voltage maps were spatially registered to the same magnetic resonance angiography (MRA) segmentation. RESULTS: The LGE levels of 3, 4, and 5SDs above blood pool mean were associated with progressively lower bipolar voltages compared to the preceding enhancement level (0.85 ± 0.33, 0.50 ± 0.22, and 0.38 ± 0.28 mV; P = .002, P < .001, and P = .048, respectively). The proportion of atrial surface area classified as scar (ie, >3 SD above blood pool mean) on preablation scans was greater in patients with postablation AF recurrence than those without recurrence (6.6% ± 6.7% vs 3.5% ± 3.0%, P = .032). The LA volume >102 mL was associated with a significantly greater proportion of LA scar (6.4% ± 5.9% vs 3.4% ± 2.2%; P = .007). CONCLUSIONS: LA scar quantified automatically by a simple objective method correlates with colocated endocardial voltage. Greater preablation scar is associated with LA dilatation and AF recurrence.