Christopher G. Bruce

BACKGROUND: Transcatheter mitral cerclage ventriculoplasty places a circumferential tensioning loop around the base of the left ventricle to reduce mitral annular dimensions and reshape ventricular geometry in patients with functional mitral regurgitation and heart failure. Early experience demonstrated reductions in mitral regurgitation and improvements in heart failure symptoms. METHODS: The National Heart, Lung, and Blood Institute Division of Intramural Research Transcatheter Mitral Cerclage Ventriculoplasty Early Feasibility Study was an investigator-initiated, prospective, multicenter study. Between 1 and 5 years, vital status, serious adverse events, routine clinical documentation, and site-reported transthoracic echocardiography findings were collected. RESULTS: Nineteen procedures were attempted in 18 participants (63% heart failure with reduced ejection fraction, 37% heart failure with preserved ejection fraction). Median age was 73 years, and 63% were female. Kaplan-Meier estimated 5-year survival was 57%. One participant underwent left ventricular assist device implantation after 2 years, and 1 participant underwent mitral transcatheter edge-to-edge repair after 3 years; none underwent heart transplantation. The study was suspended after complete heart block developed in 6 participants, including 4 requiring new cardiac implantable electronic devices. Among participants with available follow-up echocardiography, site-reported imaging demonstrated mitral regurgitation reduction and improved left ventricular ejection fraction through 5 years. Symptomatic improvement was most apparent during the first year and attenuated thereafter. CONCLUSIONS: Cerclage ventriculoplasty was associated with mitral regurgitation reduction and improved ventricular function among participants with available long-term follow-up. Symptomatic benefit was greatest during the first year and diminished thereafter, suggesting that favorable remodeling may not fully offset progression of the underlying cardiomyopathy. REGISTRATION: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT03929913.

BACKGROUND: Coronary artery obstruction is a rare but devastating complication of transcatheter aortic valve replacement. Current techniques (transcatheter leaflet modification or snorkel stenting) cannot prevent obstruction in all cases. METHODS: We created a transcatheter coronary artery bypass procedure, VECTOR (Ventriculo-Coronary Transcatheter Outward Navigation and Re-Entry), to bypass the proximal coronary artery with a covered stent graft. We tested the feasibility of creating a neo-ostium, 10 to 15 mm cephalad to the native, and bypassing the proximal coronary artery in swine. We established a proximal anastomosis using transcatheter electrosurgery to exit the aorta to the pericardium. The distal anastomosis was created using a guidewire to exit the proximal coronary artery and enter the pericardium. The points were connected, and a covered stent graft implanted to bypass the proximal vessel. Coronary angiography and intravascular ultrasound were used to assess graft patency and expansion. RESULTS: The VECTOR technique was developed in 11 and performed on the right coronary artery in 6 additional healthy swine. Proximal and distal anastomoses were successfully created, and up to 3 (total length 40 [35–45] mm) covered stent grafts were delivered to bypass the proximal vessel. There were no significant complications. All vessels had TIMI III flow on completion. CONCLUSIONS: Transcatheter coronary artery bypass with VECTOR is feasible in swine and may offer an effective solution to circumvent iatrogenic coronary artery obstruction following transcatheter aortic valve replacement when other transcatheter techniques are not possible.

BACKGROUND: Acute aortic regurgitation is life-threatening with few nonsurgical options for immediate stabilization. We propose Trans-Aortic Balloon to Ease Regurgitation Applying Counter-Pulsation (TABERNACL), a simple, on-table temporary valve using commercially available equipment to temporize acute severe aortic regurgitation. METHODS: We hypothesize that an appropriately sized commercial balloon dilatation catheter—straddling the aortic annulus and connected to a counterpulsation console—can serve as a temporizing valve to restore hemodynamic stability in acute aortic regurgitation. We performed benchtop testing of valvuloplasty, angioplasty, and sizing balloons as counterpulsation balloons. TABERNACL was assessed in vivo in a porcine model of acute aortic regurgitation (n=8). We also tested a static undersized, continuously inflated transvalvular balloon as a spacer intended physically to obstruct the regurgitant orifice. RESULTS: Benchtop testing identified that Tyshak II and PTS sizing (NuMed Braun) balloon catheters performed adequately as temporary valves (ie, complete inflation and deflation with each cycle) and resisted fatigue, in contrast to others. When TABERNACL was used in the acute severe regurgitation animals, there was immediate hemodynamic improvement, with a significant 35% increase in diastolic aortic pressure by 16 mm Hg ([95% CI, 7–25] P =0.0056), 34% reduction in left ventricular end-diastolic pressure by −7 mm Hg ([95% CI, −10 to −5] P =0.0006), improvement in the aortic diastolic index by 0.28 ([95% CI, 0.18–0.39] P =0.0009), and reversal of electrocardiographic myocardial ischemia. As an alternative, static balloon inflation across the aortic valve stabilized regurgitation hemodynamics at the expense of a new aortic gradient and caused excessive ectopy from balloon movement in the left ventricular outflow tract. CONCLUSIONS: TABERNACL improves hemodynamics and reduces coronary ischemia by electrocardiography in animals with acute severe aortic regurgitation. TABERNACL valves obstruct the diastolic regurgitant orifice without systolic obstruction. This may prove a lifesaving bridge to definitive valve replacement therapy.

Purpose: To introduce alternating current‐controlled, conductive ink‐printed marker that could be implemented with both custom and commercial interventional devices for device tracking under MRI using gradient echo, balanced SSFP, and turbo spin‐echo sequences.Methods: Tracking markers were designed as solenoid coils and printed on heat shrink tubes using conductive ink. These markers were then placed on three MR‐compatible test samples that are typically challenging to visualize during MRI scans. MRI visibility of markers was tested by applying alternating and direct current to the markers, and the effects of applied current parameters (amplitude, frequency) on marker artifacts were tested for three sequences (gradient echo, turbo spin echo, and balanced SSFP) in a gel phantom, using 0.55T and 1.5T MRI scanners. Furthermore, an MR‐compatible current supply circuit was designed, and the performance of the current‐controlled markers was tested in one postmortem animal experiment using the current supply circuit.Results: Direction and parameters of the applied current were determined to provide the highest conspicuity for all three sequences. Marker artifact size was controlled by adjusting the current amplitude, successfully. Visibility of a custom‐designed, 20‐gauge nitinol needle was increased in both in vitro and postmortem animal experiments using the current supply circuit.Conclusion: Current‐controlled conductive ink‐printed markers can be placed on custom or commercial MR‐compatible interventional tools and can provide an easy and effective solution to device tracking under MRI for three sequences by adjusting the applied current parameters with respect to pulse sequence parameters using the current supply circuit.

Purpose: Exercise‐induced dyspnea caused by lung water is an early heart failure symptom. Dynamic lung water quantification during exercise is therefore of interest to detect early stage disease. This study developed a time‐resolved 3D MRI method to quantify transient lung water dynamics during rest and exercise stress.Methods: The method was evaluated in 15 healthy subjects and 2 patients with heart failure imaged in transitions between rest and exercise, and in a porcine model of dynamic extravascular lung water accumulation through mitral regurgitation (n = 5). Time‐resolved images were acquired at 0.55T using a continuous 3D stack‐of‐spirals proton density weighted sequence with 3.5 mm isotropic resolution, and derived using a motion corrected sliding‐window reconstruction with 90‐s temporal resolution in 20‐s increments. A supine MRI‐compatible pedal ergometer was used for exercise. Global and regional lung water density (LWD) and percent change in LWD (ΔLWD) were automatically quantified.Results: A ΔLWD increase of 3.3 ± 1.5% was achieved in the animals. Healthy subjects developed a ΔLWD of 7.8 ± 5.0% during moderate exercise, peaked at 16 ± 6.8% during vigorous exercise, and remained unchanged over 10 min at rest (−1.4 ± 3.5%, p = 0.18). Regional LWD were higher posteriorly compared the anterior lungs (rest: 33 ± 3.7% vs 20 ± 3.1%, p < 0.0001; peak exercise: 36 ± 5.5% vs 25 ± 4.6%, p < 0.0001). Accumulation rates were slower in patients than healthy subjects (2.0 ± 0.1%/min vs 2.6 ± 0.9%/min, respectively), whereas LWD were similar at rest (28 ± 10% and 28 ± 2.9%) and peak exercise (ΔLWD 17 ± 10% vs 16 ± 6.8%).Conclusion: Lung water dynamics can be quantified during exercise using continuous 3D MRI and a sliding‐window image reconstruction.

Transcatheter electrosurgery describes the ability to cut and traverse tissue, at a distance, without an open surgical field and is possible using either purpose-built or off-the-shelf devices. Tissue traversal requires focused delivery of radiofrequency energy to a guidewire tip. Initially employed to cross atretic pulmonary valves, tissue traversal has enabled transcaval aortic access, recanalization of arterial and venous occlusions, transseptal access, and many other techniques. To cut tissue, the selectively denuded inner curvature of a kinked guidewire (the Flying-V) or a single-loop snare is energized during traction. Adjunctive techniques may complement or enable contemporary transcatheter procedures, whereas myocardial slicing or excision of ectopic masses may offer definitive therapy. In this contemporary review we discuss the principles of transcatheter electrosurgery, and through exemplary clinical applications highlight the range of therapeutic options offered by this versatile family of procedures.