Neo-LVOT and Transcatheter Mitral Valve Replacement: Expert Recommendations

With the advent of transcatheter mitral valve replacement (TMVR), the concept of the neo-left ventricular outflow tract (LVOT) was introduced and remains an essential component of treatment planning. This paper describes the LVOT anatomy and provides a step-by-step computed tomography methodology to segment and measure the neo-LVOT while discussing the current evidence and outstanding challenges. It also discusses the technical and hemodynamic factors that play a major role in assessing the neo-LVOT. A summary of expert-based recommendations about the overall risk of LVOT obstruction in different scenarios is presented along with the currently available methods to reduce the risk of LVOT obstruction and other post-procedural complications

Transcatheter Valve Implantation in Failed Surgically Inserted Bioprosthesis Review and Practical Guide to Echocardiographic Imaging in Valve-in-Valve Procedures

AbstractAn increased use of bioprosthetic heart valves has stimulated an interest in possible transcatheter options for bioprosthetic valve failure given the high operative risk. The encouraging results of transcatheter aortic valve implantation in high-risk surgical candidates with native disease have led to the development of the transcatheter valve-in-valve (VIV) procedures for failed bioprostheses. VIV procedures are unique in many ways, and there is an increased need for multimodality imaging in a team-based approach. The echocardiographic approach to VIV procedures has not previously been described. In this review, we summarize key echocardiographic requirements for optimal patient selection, procedural guidance, and immediate post-procedural assessment for VIV procedures

Prospective Study of TMVR Using Balloon-Expandable Aortic Transcatheter Valves in MAC: MITRAL Trial 1-Year Outcomes

OBJECTIVES: The aim of this study was to evaluate 1-year outcomes of valve-in-mitral annular calcification (ViMAC) in the MITRAL (Mitral Implantation of Transcatheter Valves) trial. BACKGROUND: The MITRAL trial is the first prospective study evaluating the feasibility of ViMAC using balloon-expandable aortic transcatheter heart valves. METHODS: A multicenter prospective study was conducted, enrolling high-risk surgical patients with severe mitral annular calcification and symptomatic severe mitral valve dysfunction at 13 U.S. sites. RESULTS: Between February 2015 and December 2017, 31 patients were enrolled (median age 74.5 years [interquartile range (IQR): 71.3 to 81.0 years], 71% women, median Society of Thoracic Surgeons score 6.3% [IQR: 5.0% to 8.8%], 87.1% in New York Heart Association functional class III or IV). Access was transatrial (48.4%), transseptal (48.4%), or transapical (3.2%). Technical success was 74.2%. Left ventricular outflow tract obstruction (LVOTO) with hemodynamic compromise occurred in 3 patients (transatrial, n = 1; transseptal, n = 1; transapical, n = 1). After LVOTO occurred in the first 2 patients, pre-emptive alcohol septal ablation was implemented to decrease risk in high-risk patients. No intraprocedural deaths or conversions to open heart surgery occurred during the index procedures. All-cause mortality at 30 days was 16.7% (transatrial, 21.4%; transseptal, 6.7%; transapical, 100% [n = 1]; p = 0.33) and at 1 year was 34.5% (transatrial, 38.5%; transseptal, 26.7%; p = 0.69). At 1-year follow-up, 83.3% of patients were in New York Heart Association functional class I or II, the median mean mitral valve gradient was 6.1 mm Hg (IQR: 5.6 to 7.1 mm Hg), and all patients had ≤1+ mitral regurgitation. CONCLUSIONS: At 1 year, ViMAC was associated with symptom improvement and stable transcatheter heart valve performance. Pre-emptive alcohol septal ablation may prevent transcatheter mitral valve replacement-induced LVOTO in patients at risk. Thirty-day mortality of patients treated via transseptal access was lower than predicted by the Society of Thoracic Surgeons score. Further studies are needed to evaluate safety and efficacy of ViMAC

Effect of Valve Design on the Stent Internal Diameter of a Bioprosthetic Valve A Concept of True Internal Diameter and Its Implications for the Valve-in-Valve Procedure

The goal of this study was to provide a measurement of the true internal diameter (ID) of various surgical heart valves (SHV) to facilitate the valve-in-valve (VIV) procedure. During a VIV procedure, it is important to choose the right of the transcatheter heart valve (THV). Most users use the stent ID of an SHV to select the appropriate THV size. Echocardiography and computed tomography measurements are not yet standardized for measuring the ID of a variety of SHVs. Hence, we measured the true ID of SHV to assess the effect of valve design on the stent ID. Thirteen types of stented and 3 types of stentless valves were evaluated. True ID measurements were obtained using calipers and Hegar dilators. These were compared with the stent ID measurements. Fluoroscopy was used to confirm the impact of SHV designs on the true ID. Caliper measurements were found to be inaccurate and are hence not recommended. Hegar dilator measurements revealed a trend of reduction in stent ID. Porcine valves were most affected by their design, with reduction in the stent ID by at least 2 mm; pericardial valves with leaflets sutured inside the stent had the stent ID reduced by at least 1 mm, and SHV with leaflets sutured outside the stent had no effect on stent ID. In the majority of SHV designs, there is a reduction in the stent ID as a result of leaflet tissue. This is important in borderline sizes to avoid problems associated with oversizing and also to confirm suitability for the VIV procedure in the smaller label sizes of SHV

Distribution of Calcium in the Ascending Aorta in Patients Undergoing Transcatheter Aortic Valve Implantation and Its Relevance to the Transaortic Approach

ObjectivesThis study sought to identify how many patients suitable for transcatheter aortic valve implantation (TAVI) would have a contraindication for the transaortic (TAo) approach due to ascending aortic calcification.BackgroundTAo is an emerging approach for implantation of the Sapien valve through the ascending aorta. A “porcelain aorta” is often considered a contraindication for the TAo approach. This may not always be true, as the TAo procedure requires a small calcium-free area for the purse-string suture, usually in the upper outer quadrant of the distal ascending aorta, identified as the “TAo zone.”MethodsA total of 237 patients underwent TAVI between February 2008 and June 2011. Multislice computed tomography scans (MSCT) were analyzed for distribution of calcium with special attention to the TAo zone. Each MSCT was interrogated in cross section and three dimensional (3D) reconstructions. Correlation between the calcium distribution on MSCT and the 3D reconstruction with the clinical findings was sought in patients undergoing the TAo procedure.ResultsThe vast majority of patients had calcification in the aortic arch (n = 154, 64.9%) and aortic root (n = 220, 92.8%). Of the 237 patients, only 1 patient had diffuse calcification in the ascending aorta, including the TAo zone, thus precluding a TAo procedure. MSCT and 3D reconstruction data in the 33 patients who underwent a TAo procedure, including 6 who were identified as having porcelain aorta preoperatively, correlated very well with the absence of calcium in the TAo zone during surgery. There were no post-procedure neurological events in this group.ConclusionsConventionally defined porcelain aorta should not be considered a contraindication for performing TAVI by the TAo approach

Rhabdomyolysis and compartment syndrome in a bodybuilder undergoing minimally invasive cardiac surgery

Rhabdomyolysis is the result of skeletal muscle tissue injury and is characterized by elevated creatine kinase levels, muscle pain, and myoglobinuria. It is caused by crush injuries, hyperthermia, drugs, toxins, and abnormal metabolic states. This is often difficult to diagnose perioperatively and can result in renal failure and compartment syndrome if not promptly treated. We report a rare case of inadvertent rhabdomyolysis and compartment syndrome in a bodybuilder undergoing minimally invasive cardiac surgery. The presentation, differential diagnoses, and management are discussed. Hyperkalemia may be the first presenting sign. Early recognition and management are essential to prevent life-threatening complications

Left ventricular outflow obstruction predicts increase in systolic pressure gradients and blood residence time after transcatheter mitral valve replacement

Abstract Left ventricular outflow tract (LVOT) obstruction is a relatively common consequence of transcatheter mitral valve replacement (TMVR). Although LVOT obstruction is associated with heart failure and adverse remodelling, its effects upon left ventricular hemodynamics remain poorly characterised. This study uses validated computational models to identify the LVOT obstruction degree that causes significant changes in ventricular hemodynamics after TMVR. Seven TMVR patients underwent personalised flow simulations based on pre-procedural imaging data. Different virtual valve configurations were simulated in each case, for a total of 32 simulations, and the resulting obstruction degree was correlated with pressure gradients and flow residence times. These simulations identified a threshold LVOT obstruction degree of 35%, beyond which significant deterioration of systolic function was observed. The mean increase from baseline (pre-TMVR) in the peak systolic pressure gradient rose from 5.7% to 30.1% above this threshold value. The average blood volume staying inside the ventricle for more than two cycles also increased from 4.4% to 57.5% for obstruction degrees above 35%, while the flow entering and leaving the ventricle within one cycle decreased by 13.9%. These results demonstrate the unique ability of modelling to predict the hemodynamic consequences of TMVR and to assist in the clinical decision-making process