Iatrogenic atrial septal defect closure after transseptal mitral valve interventions: Indications and outcomes.

OBJECTIVES: Review indications and outcomes for transcatheter iatrogenic atrial septal defect (iASD) closure in patients undergoing MitraClip or transseptal (TS) mitral valve-in-valve/ring (ViV/ViR) procedures. BACKGROUND: Mitral valve transcatheter interventions require large-diameter TS sheaths that can result in iASDs that necessitate post-procedure transcatheter closure. Although the presence of iASD has been well-described, indications for closure and outcomes after TS mitral valve interventions have not been reported. METHODS: Patients undergoing MitraClip repair and ViV or ViR transcatheter mitral valve replacement (TMVR) from February 14, 2014, to January 16, 2018, were studied retrospectively in this single center study. RESULTS: Seventeen patients had iASD closure: 11 MitraClip and 6 TMVR (5 ViV, 1 ViR). Indications for iASD closure included large iASD (n = 7), large left-to-right shunt (n = 9), pulmonary hypertension (n = 8), large right-to-left shunt (n = 1), severe RV dysfunction (n = 2), thin/aneurysmal septum (n = 2), and mobile material on pacemaker leads (n = 2). Closures were performed without complications using Amplatzer septal occluders. At 30 days, 94% of subjects (n = 16) were alive with one patient deceased from unknown causes. There were no myocardial infarctions or strokes. At 12 months, follow-up was available for 14 of 17 patients, and 71% of patients (10/14) were alive. One patient died due to cardiac causes, two from noncardiac causes and one for unknown reasons. There was one myocardial infarction, one intraparenchymal hemorrhage, and no ischemic strokes. CONCLUSIONS: The most common reasons for iASD closure after TS MV procedures are: large ASD unlikely to spontaneously close, large left-to-right shunt, and pulmonary hypertension. Patients who required iASD closure had low 30-day mortality but higher one-year mortality potentially reflecting a population with substantial comorbidities.

Intraprocedural direct left atrial and wedge pressure correlation during transcatheter mitral valve repair: Results from a single center registry.

OBJECTIVES: This study investigates the correlation of occlusive wedge pressure (WP) with direct left atrial (LA) pressure in patients with severe mitral regurgitation (MR) undergoing transcatheter mitral valve repair (TMVr) with MitraClip. BACKGROUND: There is interest in acquiring objective hemodynamic parameters for intraprocedural guidance in patients undergoing MitraClip. METHODS: The study included 94 patients with severe MR at prohibitive surgical risk who underwent MitraClip at the University of California Davis Medical Center between 2014 and 2016. RESULTS: An average of 1.8 ± 0.7 clips were used to achieve MR grade of 2+ or less in 99% of patients. Correlation analysis of all (n = 236) pre-clip, inter-clip, and final-clip WP and LA pressures yielded a Pearson's R (r) of 0.85 and 0.79 for mean WP vs mean LA and WP V vs LA V, respectively. Median LA V to mean LA ratio (LAV:mLA) was 1.75 (IQR 1.5-1.9). 79% (n = 74) of patients had LAV:mLA ratio ≥ 1.5 with associated WP V vs LA V correlation (r) of 0.83. In patients with LAV:mLA ratio < 1.5, the correlation (r) was 0.69. Baseline characteristics were not significantly different between patients with LAV:mLA ratio ≥ 1.5 and patients with LAV:mLA ratio < 1.5. Post-procedure, median LA V: mean LA ratio decreased from 1.75 to 1.4, P = 0.0001. CONCLUSIONS: Correlation between WP and direct LA pressure in patients with severe MR undergoing Mitraclip is modest. Caution is advised when using WP to approximate LA pressure intraprocedurally, especially in patients with baseline low LAV:mLA ratios.

Initial clinical experience with the FlexPoint Steerable Transseptal Needle in left-sided structural heart procedures.

OBJECTIVES: The purpose of this study is to describe the initial clinical experience with a steerable transseptal needle (STSN) for left-sided structural heart procedures. BACKGROUND: Targeted transseptal (TS) puncture is required for many structural heart procedures, and the use of a steerable needle has not previously been described. METHODS: Consecutive patients undergoing structural heart interventions with targeted TS puncture under transesophageal echocardiographic (TEE) and fluoroscopic guidance were studied. The STSN was used in all patients with a standard commercial TS sheath. Deflection of the needle was performed "real time" to achieve localization of the TS puncture site. RESULTS: Twenty-seven patients underwent STSN puncture of the interatrial septum. In all cases, the needle could be deflected in vivo to achieve optimal tenting and localization of the puncture site without having to remove or reshape the needle. The needle was deflected to match a wide range of right atrial diameters (width 4.3 ± 0.9 cm and length 6.0 ± 0.9 cm in the 4-chamber view). In two patients with prior mitral valve surgery and a fibrotic septum, assisted crossing was achieved using the piercing stylet in one patient, and Bovie energy in the other. There were no procedural complications, and all patients had successful completion of the intended structural heart procedure. CONCLUSIONS: The STSN needle can be used to target the intended puncture location on the interatrial septum with real-time adjustable deflection without the need to remove and reshape the needle. In all cases crossing was successful and there were no complications.

Embolization of the first diagonal branch of the left anterior descending coronary artery as a porcine model of chronic trans-mural myocardial infarction.

BACKGROUND: Although the incidence of acute death related to coronary artery disease has decreased with the advent of new interventional therapies, myocardial infarction remains one of the leading causes of death in the US. Current animal models developed to replicate this phenomenon have been associated with unacceptably high morbidity and mortality. A new model utilizing the first diagonal branch of the left anterior descending artery (D1-LAD) was developed to provide a clinically relevant lesion, while attempting to minimize the incidence of adverse complications associated with infarct creation. METHODS: Eight Yucatan miniature pigs underwent percutaneous embolization of the D1-LAD via injection of 90 µm polystyrene micro-spheres. Cardiac structure and function were monitored at baseline, immediately post-operatively, and at 8-weeks post-infarct using transthoracic echocardiography. Post-mortem histopathology and biochemical analyses were performed to evaluate for changes in myocardial structure and extracellular matrix (ECM) composition respectively. Echocardiographic data were evaluated using a repeated measures analysis of variance followed by Tukey's HSD post hoc test. Biochemical analyses of infarcted to non-infarcted myocardium were compared using analysis of variance. RESULTS: All eight pigs successfully underwent echocardiography prior to catheterization. Overall procedural survival rate was 83% (5/6) with one pig excluded due to failure of infarction and another due to deviation from protocol. Ejection fraction significantly decreased from 69.7 ± 7.8% prior to infarction to 50.6 ± 14.7% immediately post-infarction, and progressed to 48.7 ± 8.9% after 8-weeks (p = 0.011). Left ventricular diameter in systole significantly increased from 22.6 ± 3.8 mm pre-operatively to 30.9 ± 5.0 mm at 8 weeks (p = 0.016). Histopathology showed the presence of disorganized fibrosis on hematoxylin and eosin and Picro Sirius red stains. Collagen I and sulfated glycosaminoglycan content were significantly greater in the infarcted region than in normal myocardium (p = 0.007 and p = 0.018, respectively); however, pyridinoline crosslink content per collagen I content in the infarcted region was significantly less than normal myocardium (p = 0.048). CONCLUSION: Systolic dysfunction and changes in ECM composition induced via embolization of the D1-LAD closely mimic those found in individuals with chronic myocardial infarction (MI), and represents a location visible without the need for anesthesia. As a result, this method represents a useful model for studying chronic MI.

Transcatheter Mitral Valve Direct Annuloplasty with the Millipede IRIS Ring.

Mitral valve ring annuloplasty is a surgical gold standard and is used routinely during surgical mitral valve repair of primary or secondary mitral regurgitation. The Millipede IRIS annuloplasty ring is the first transcatheter, transfemoral, transseptal, semirigid, complete annuloplasty ring to be delivered to the mitral valve annulus. Initial results in humans demonstrate that the Millipede IRIS ring is safe, and can effectively reduce the mitral annular diameter leading to a clinically significant reduction or elimination of mitral regurgitation.

Early experience with Millipede IRIS transcatheter mitral annuloplasty.

The IRIS mitral annuloplasty ring is a transcatheter, transfemoral and transseptal-delivered complete, semi-rigid annuloplasty ring. The IRIS system mimics surgical annuloplasty by reducing the mitral septal-lateral dimension and improving leaflet coaptation. We report the early experience with the IRIS system in seven patients. These patients had 3-4+ mitral regurgitation (MR) with annular dilation and were symptomatic NYHA II-IV with LV end systolic dimensions ≤65 mm. Patients were excluded for LVEF <20%, aortic valve disease, right-sided heart failure and PA systolic pressure >70 mmHg. Baseline and 30-day transthoracic echocardiography and CT imaging was performed. In phase 1, 4 patients had surgical IRIS mitral ring implantation. In phase 2, 3 patients had transfemoral, transseptal delivery of the IRIS mitral ring. There was no procedural death, or MI. The mitral SL diameter was reduced from 38.0±4.1 to 25.9±4.9 mm at 30 days (31.8% SL reduction, n=7). MR was reduced from baseline 3-4+ to 0-1+ in all patients at 30 days. There were improvements in NYHA class and there was a decrease in diastolic LV volumes from 182.4±54.3 to 115.3±98.8 mL at 30 days (36.8% reduction). Based on these initial positive findings, ongoing clinical trials are underway to further evaluate the safety and efficacy of the IRIS ring.

Interstitial lung abnormality is prevalent and associated with worse outcome in patients undergoing transcatheter aortic valve replacement.

BACKGROUND: Interstitial lung abnormality (ILA) is found in 5-10% of the general population and is associated with increased mortality risk. Risk factors for ILA, including advanced age and smoking history also increase the risk for aortic stenosis (AS). Transcatheter aortic valve replacement (TAVR) has become an increasingly utilized intervention for patients with severe AS, and requires a high-resolution computed tomography (HRCT) of the chest to assess aortic valve dimensions. OBJECTIVES: To determine the prevalence and clinical significance of ILA on HRCT performed in patients referred for TAVR. METHODS: Consecutive pre-TAVR HRCTs performed over a 5-year period were reviewed. ILA was defined as bilateral, nondependent reticular opacities. All-cause mortality among TAVR recipients was compared between ILA cases and non-ILA controls matched 2:1 by age and gender using Cox proportional hazards regression and the Kaplan Meier estimator. RESULTS: Of 623 HRCTs screened, ILA was detected in 92 (14.7%), including 62 patients that underwent TAVR. Among ILA cases, 17 (27.4%) had a typical or probable usual interstitial pneumonia pattern, suggesting a diagnosis of idiopathic pulmonary fibrosis. Survival was worse in ILA cases compared to non-ILA controls (p = 0.008) and ILA was an independent predictor of mortality after multivariable adjustment (HR 3.29, 95% CI 1.34-8.08; p = 0.009). CONCLUSIONS: ILA is a common finding among patients with severe AS and is associated with increased mortality in those undergoing TAVR. Further research is needed to elucidate the biology underpinning this observation and determine whether ILA evaluation and risk stratification modulates this mortality risk.

Reconstruction of pulmonary artery with porcine small intestinal submucosa in a lamb surgical model: Viability and growth potential.

OBJECTIVES: This study investigated the time-dependent remodeling and growth potential of porcine small intestine submucosa as a biomaterial for the reconstruction of pulmonary arteries in a lamb model. METHODS: Left pulmonary arteries were partially replaced with small intestine submucosal biomaterial in 6 lambs. Two animals each were humanely killed at 1, 3, and 6 months. Computed tomographic angiography, macroscopic examination of the implanted patch, and microscopic analysis of tissue explants were performed. RESULTS: All animals survived without complications. Patency and arborization of the pulmonary arteries were detected 6 months after implantation. There was no macroscopic narrowing or aneurysm formation in the patch area. The luminal appearance of the patch was similar to the intimal layer of the adjacent native pulmonary artery. Scanning electron microscopy showed that the luminal surface of the patch was covered by confluent cells. Immunohistochemical examination confirmed endothelialization of the luminal side of the patch in all of the explanted patches. The presence of smooth muscle cells in the medial layer was confirmed at all time points; however, expression of elastin, growth of the muscular layer, and complete degradation of patch material were detectable only after 6 months. The presence of c-Kit-positive cells suggests migration of multipotent cells into the patch, which may play a role in remodeling the small intestine submucosal biomaterial. CONCLUSIONS: Our data confirmed that remodeling and growth potential of the small intestine submucosal biomaterial are time dependent. Additional experiments are required to investigate the stability of the patch material over a longer period.