Christopher Naoum

Predicting LVOT Obstruction in Transcatheter Mitral Valve Implantation: Concept of the Neo-LVOT

Outflow tract obstruction is a feared and potentially lethal complication of transcatheter mitral valve replacement (TMVR), mitral valve-in-valve (ViV), and valve-in-ring (ViR) procedures as well as implantation of transcatheter heart valves in calcific mitral valve disease. These procedures

Multimodality Imaging in the Context of Transcatheter Mitral Valve Replacement: Establishing Consensus Among Modalities and Disciplines

Transcatheter mitral valve implantation (TMVI) represents a promising approach to treating mitral valve regurgitation in patients at increased risk of perioperative mortality. Similar to transcatheter aortic valve replacement (TAVR), TMVI relies on pre- and periprocedural noninvasive imaging. Although these imaging modalities, namely echocardiography, computed tomography, and fluoroscopy, are well established in TAVR, TMVI has entirely different requirements. Approaches and nomenclature need to be standardized given the multiple disciplines involved. Herein we provide an overview of anatomical principles and definitions, a methodology for anatomical quantification, and perioperative guidance.

Left Atrial Compression and the Mechanism of Exercise Impairment in Patients With a Large Hiatal Hernia

OBJECTIVES The purpose of this study was to determine the association between cardiac compression and exercise impairment in patients with a large hiatal hernia (HH). BACKGROUND Dyspnea and exercise impairment are common symptoms of a large HH with unknown pathophysiology. Studies evaluating the contribution of cardiac compression to the pathogenesis of these symptoms have not been performed. METHODS We collected clinical data from a consecutive series of 30 patients prospectively evaluated with resting and stress echocardiography, cardiac computed tomography, and respiratory function testing before and after laparoscopic HH repair. Left atrial (LA), inferior pulmonary vein, and coronary sinus compression was analyzed in relation to exercise capacity (metabolic equivalents [METs] achieved on Bruce treadmill protocol). RESULTS Exertional dyspnea was present in 25 of 30 patients (83%) despite normal mean baseline respiratory function. Moderate to severe LA compression was qualitatively present in 23 of 30 patients (77%) on computed tomography. Right and left inferior pulmonary vein and coronary sinus compression was present in 11 of 30 (37%), 12 of 30 (40%), and 26 of 30 (87%) patients, respectively. Post-operatively, New York Heart Association functional class and exercise capacity improved significantly (number of patients in New York Heart Association functional classes I, II, III, and IV: 6, 11, 11, and 2 vs. 26, 4, 0, and 0, respectively, p < 0.001; METs [percentage predicted]: 75 ± 24% vs. 112 ± 23%, p < 0.001) and resolution of cardiac compression was observed. Absolute change in LA diameter on the echocardiogram was the only independent cardiorespiratory predictor of exercise capacity improvement post-operatively (p = 0.006). CONCLUSIONS We demonstrate, for the first time, marked exercise impairment and cardiac compression in patients with a large HH and normal respiratory function. After HH repair, exercise capacity improves significantly and correlates with resolution of LA compression.

Perioperative myocardial necrosis in patients at high cardiovascular risk undergoing elective non-cardiac surgery.

Objective Cardiovascular complications are important causes of morbidity and mortality in elective non-cardiac surgery. Although difficult to diagnose, perioperative myocardial infarction (MI) remains prognostically important. High-sensitivity troponin T (hs-TnT) assays allow detection of very minor damage to cardiac muscle. These assays are yet to be fully evaluated in the perioperative setting. Our aim was to determine the incidence and predictors of myocardial necrosis in patients at high cardiovascular risk undergoing elective non-cardiac surgery using hs-TnT. Design Prospective observational cohort study. Patients 352 consecutive patients undergoing elective major non-cardiac surgery prescribed antiplatelet therapy for primary or secondary cardiovascular event prevention. Main outcome measure The incidence of elevated preoperative hs-TnT (≥14 ng/litre), hs-TnT-defined perioperative myocardial necrosis (≥ 14ng/litre and 50% increase from preoperative level), and perioperative MI were determined in relation to patient and surgical factors. Results Preoperative hs-TnT was elevated in 31% and postoperative myocardial necrosis occurred in 22% of patients. Predictors of elevated baseline hs-TnT included age (OR 1.10, p<0.001), male gender (OR 2.91, p<0.001), diabetes requiring insulin therapy (OR 4.85, p=0.004) and chronic kidney disease (OR 3.60, p<0.001). Independent predictors of perioperative myocardial necrosis were age (OR 1.07, p<0.001), intraoperative hypotension (OR 3.67, p=0.001) and orthopaedic surgery (OR 2.46, p=0.005). Only 2% of patients suffered clinically apparent MI. Elevated preoperative hs-TnT did not predict perioperative myocardial necrosis or MI. Conclusions Perioperative myocardial damage occurs frequently in patients undergoing elective non-cardiac surgery, although the majority of events are clinically undetected. Age and intraoperative hypotension are independent predictors of myocardial necrosis in this setting.

Prediction of fluoroscopic angulation and coronary sinus location by CT in the context of transcatheter mitral valve implantation

BACKGROUND We sought to determine if preprocedural CT can predict appropriate fluoroscopic angulations to achieve a coplanar view during transcatheter mitral valve implantation (TMVI) and to assess the relationship of the mitral annulus and the coronary sinus to determine the feasibility of using this as an additional landmark on fluoroscopy. METHODS With CT, the mitral annulus was segmented in 25 patients with functional mitral regurgitation. After this, optimal projection curves were plotted and the necessary angulations for specific views parallel to the trigone-to-trigone line (TT view) and septal-to-lateral distance (SL view) were noted. The outer contour of the coronary sinus and great cardiac vein were segmented to simulate a guide wire, and its relation to the annular plane was assessed. Employed angulations and coplanarity of device depiction were investigated in 4 patients who underwent TMVI. RESULTS The mitral annulus is oriented in an anterior superior fashion with tilting to the right. SL and TT views were found at 29.4 ± 9.0° right anterior oblique (RAO), 20.1 ± 8.7° cranial (CAU) and 81.6 ± 18.9° RAO, 56.7 ± 8.0° caudal (CAU). The optimal projection curve and the relationship of coronary sinus to the mitral annular plane showed a wide intersubject variability. Commonly, the coronary sinus passed along the atrial wall with a mean distance of 13.2 ± 3.7 mm toward the mitral annular plane at P2 and 1.4 ± 3.1 mm anteriorly in alignment with the TT line. Coplanar depiction of the TMVI prosthesis was achieved in all 4 patients, with a compromise view chosen on the optimal projection curve between the TT view and SL view. CONCLUSION CT allows for prediction of optimal fluoroscopic angulations to achieve a coplanar view of the mitral annulus. The relationship of the coronary sinus to the mitral annulus is variable and preprocedural CT segmentation may allow for a more patient-specific approach to the use of a coronary sinus guide wire as a fluoroscopic landmark.

Mitral Annular Dimensions and Geometry in Patients With Functional Mitral Regurgitation and Mitral Valve Prolapse : Implications for Transcatheter Mitral Valve Implantation

OBJECTIVES The aims of this study were to determine D-shaped mitral annulus (MA) dimensions in control subjects without significant cardiac disease and in patients with moderate to severe mitral regurgitation (MR) being considered for transcatheter mitral therapy and to determine predictors of annular size, using cardiac computed tomography. BACKGROUND The recently introduced D-shaped method of MA segmentation represents a biomechanically appropriate approach for annular sizing prior to transcatheter mitral valve implantation. METHODS Patients who had retrospectively gated cardiac computed tomography performed at our institution (2012 to 2014) and were free of significant cardiac disease were included as controls (n = 88; 56 ± 11 years of age; 47% female) and were compared with patients with moderate or severe MR due to functional mitral regurgitation (FMR) (n = 27) or mitral valve prolapse (MVP) (n = 32). MA dimensions (projected area, perimeter, intercommissural, and septal-to-lateral distance), maximal left atrial (LA) volumes, and phasic left ventricular volumes were measured. RESULTS MA dimensions were larger in patients with FMR or MVP compared with controls (area index 4.7 ± 0.6 cm(2)/m(2), 6.0 ± 1.3 cm(2)/m(2), and 7.3 ± 1.7 cm(2)/m(2); perimeter index 59 ± 5 mm/m(2), 67 ± 9 mm/m(2), and 75 ± 10 mm/m(2); intercommissural distance index 20.2 ± 1.9 mm/m(2), 21.2 ± 3.1 mm/m(2), and 24.7 ± 3.2 mm/m(2); septal-to-lateral distance index 14.8 ± 1.6, 18.1 ± 3.3, and 19.5 ± 3.4 mm/m(2) in controls and patients with FMR and MVP, respectively; p < 0.05 between controls and MR subgroups). Absolute MA area was 18% larger in patients with MVP than patients with FMR (13.0 ± 2.9 cm(2) vs. 11.0 ± 2.3 cm(2); p = 0.006). Although LA and left ventricular volumes were both independently associated with MA area index in controls and patients with MVP, only LA volume was associated with annular size in patients with FMR. CONCLUSIONS Moderate to severe MR was associated with increased MA dimensions, especially among patients with MVP compared with control subjects without cardiac disease. Moreover, unlike in controls and patients with MVP, annular enlargement in FMR was more closely associated with LA dilation.

Cardiac Computed Tomography and Magnetic Resonance Imaging in the Evaluation of Mitral and Tricuspid Valve Disease: Implications for Transcatheter Interventions

Transcatheter interventions to treat mitral and tricuspid valve disease are becoming increasingly available because of the growing number of elderly patients with significant comorbidities or high operative risk. Thorough clinical and imaging evaluation in these patients is essential. The latter involves both characterization of the mechanism and severity of valvular disease as well as determining the hemodynamic consequences and extent of ventricular remodeling, which is an important predictor of future outcomes. Moreover, an assessment of the suitability and risk of complications associated with device-specific therapies is also an important component of the preprocedural evaluation in this cohort. Although echocardiography including 2-dimensional and 3-dimensional methods has an important role in the initial assessment and procedural guidance, cross-sectional imaging, including both computed tomographic imagning and cardiac magnetic resonance imaging, is increasingly being integrated into the evaluation of mitral and tricuspid valve disease. In this review, we discuss the role of cross-sectional imaging in mitral and tricuspid valve disease, primarily valvular regurgitation assessment, with an emphasis on the preprocedural evaluation and implications for transcatheter interventions.

Computed tomography assessment for transcatheter aortic valve in valve implantation: The vancouver approach to predict anatomical risk for coronary obstruction and other considerations

Valve-in-valve implantation of a transcatheter heart valve into a failed bioprosthetic heart valve has emerged as a treatment alternative to repeat conventional surgery. This requires careful pre-procedural assessment using non-invasive imaging to identify patients at risk for procedure related adverse events, such as ostial coronary occlusion. Herein we report how to comprehensively assess aortic root anatomy using computed tomography prior to transcatheter valve implantation for failed bioprosthetic aortic valves.

Clinical Outcomes and Imaging Findings in Women Undergoing TAVR.

Transcatheter aortic valve replacement (TAVR) has become the standard of care for patients with hemodynamically severe aortic stenosis who are symptomatic but deemed too high risk for surgery. Recent reports suggest that sex differences exist in outcomes following TAVR and in the diagnostic imaging evaluation of patients being considered for TAVR. In this review, the authors explore the differences between men and women in baseline characteristics and outcomes following TAVR, as well as sex differences in the imaging findings of severe aortic stenosis (AS) including the diagnostic challenges in the hemodynamic assessment of severe AS in elderly women, differences in aortic valvular calcification and in the associated myocardial response to severe AS. Additionally, sex differences in imaging findings as they relate to post-TAVR complications including coronary obstruction, annular rupture and prosthesis-patient mismatch are also discussed.

Three-Dimensional Echocardiography Compared With Computed Tomography to Determine Mitral Annulus Size Before Transcatheter Mitral Valve Implantation

Background—Previously, through the use of computed tomography (CT), it has been proposed that D-shaped versus saddle-shaped mitral annulus (MA) segmentation is more biomechanically appropriate to determine transcatheter mitral valve implantation size and eligibility. Methods and Results—Forty-one patients with severe mitral regurgitation being considered for transcatheter mitral valve implantation who had undergone cardiac CT and 3-dimensional transesophageal echocardiography (3D-TEE) were retrospectively evaluated. A standardized segmentation protocol for the D-shaped MA was developed using Philips Q-Laboratory mitral valve quantification software. MA dimensions were compared using Spearman’s rank correlation and Bland–Altman analysis. Inter- and intraobserver agreement was quantified by intraclass correlation coefficient and Bland–Altman analysis. Mean age was 77±14 years; 71% male (n=29); mitral regurgitation pathogenesis was functional in 54% (n=22) and myxomatous in 46% (n=19). Mean MA area and circumference by 3D-TEE and CT were 11.3±2.7 versus 11.4±3.0 (P=0.67) and 124.1±15.6 versus 123.9±15.5 (P=0.79), respectively, with excellent correlation between modalities (r=0.84 and r=0.86; P<0.0001) and no systematic bias (−0.20±1.8 cm2 [−3.7 cm2; 3.3 cm2], 0.37±9 mm [−18.0 mm; 17.27 mm]). Mean septal-to-lateral and inter-trigone distances by 3D-TEE and CT were 33.2±4.7 versus 32.5±4.4 (P=0.24) and 31.7±3.5 versus 32.6±3.6 (P=0.06), respectively, with good correlation (r=0.69 and r=0.71; P<0.0001) and no systematic bias (0.77±3.8 mm [−6.7 mm; 8.2 mm], −1.5±3.1 mm [−4.6 mm; 7.6 mm]). There was excellent intra- and interobserver agreement according to intraclass correlation coefficients >0.90 for all parameters. Conclusions—Similar to cardiac CT, 3D-TEE allows for D-shaped MA segmentation with no systematic difference in MA dimensions between modalities. This study supports the utilization of 3D-TEE as a complementary tool to CT assessment of the D-shaped MA to determine transcatheter mitral valve implantation size.