An interventional MRI guidewire combining profile and tip conspicuity for catheterization at 0.55T.

PURPOSE: We describe a clinical grade, "active", monopole antenna-based metallic guidewire that has a continuous shaft-to-tip image profile, a pre-shaped tip-curve, standard 0.89 mm (0.035″) outer diameter, and a detachable connector for catheter exchange during cardiovascular catheterization at 0.55T. METHODS: Electromagnetic simulations were performed to characterize the magnetic field around the antenna whip for continuous tip visibility. The active guidewire was manufactured using medical grade materials in an ISO Class 7 cleanroom. RF-induced heating of the active guidewire prototype was tested in one gel phantom per ASTM 2182-19a, alone and in tandem with clinical metal-braided catheters. Real-time MRI visibility was tested in one gel phantom and in-vivo in two swine. Mechanical performance was compared with commercial equivalents. RESULTS: The active guidewire provided continuous "profile" shaft and tip visibility in-vitro and in-vivo, analogous to guidewire shaft-and-tip profiles under X-ray. The MRI signal signature matched simulation results. Maximum unscaled RF-induced temperature rise was 5.2°C and 6.5°C (3.47 W/kg local background specific absorption rate), alone and in tandem with a steel-braided catheter, respectively. Mechanical characteristics matched commercial comparator guidewires. CONCLUSION: The active guidewire was clearly visible via real-time MRI at 0.55T and exhibits a favorable geometric sensitivity profile depicting the guidewire continuously from shaft-to-tip including a unique curved-tip signature. RF-induced heating is clinically acceptable. This design allows safe device navigation through luminal structures and heart chambers. The detachable connector allows delivery and exchange of cardiovascular catheters while maintaining guidewire position. This enhanced guidewire design affords the expected performance of X-ray guidewires during human MRI catheterization.

Dynamic lung water MRI during exercise stress.

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.

Dynamic pressure-volume loop analysis by simultaneous real-time cardiovascular magnetic resonance and left heart catheterization.

BACKGROUND: Left ventricular (LV) contractility and compliance are derived from pressure-volume (PV) loops during dynamic preload reduction, but reliable simultaneous measurements of pressure and volume are challenging with current technologies. We have developed a method to quantify contractility and compliance from PV loops during a dynamic preload reduction using simultaneous measurements of volume from real-time cardiovascular magnetic resonance (CMR) and invasive LV pressures with CMR-specific signal conditioning. METHODS: Dynamic PV loops were derived in 16 swine (n = 7 naïve, n = 6 with aortic banding to increase afterload, n = 3 with ischemic cardiomyopathy) while occluding the inferior vena cava (IVC). Occlusion was performed simultaneously with the acquisition of dynamic LV volume from long-axis real-time CMR at 0.55 T, and recordings of invasive LV and aortic pressures, electrocardiogram, and CMR gradient waveforms. PV loops were derived by synchronizing pressure and volume measurements. Linear regression of end-systolic- and end-diastolic- pressure-volume relationships enabled calculation of contractility. PV loops measurements in the CMR environment were compared to conductance PV loop catheter measurements in 5 animals. Long-axis 2D LV volumes were validated with short-axis-stack images. RESULTS: Simultaneous PV acquisition during IVC-occlusion was feasible. The cardiomyopathy model measured lower contractility (0.2 ± 0.1 mmHg/ml vs 0.6 ± 0.2 mmHg/ml) and increased compliance (12.0 ± 2.1 ml/mmHg vs 4.9 ± 1.1 ml/mmHg) compared to naïve animals. The pressure gradient across the aortic band was not clinically significant (10 ± 6 mmHg). Correspondingly, no differences were found between the naïve and banded pigs. Long-axis and short-axis LV volumes agreed well (difference 8.2 ± 14.5 ml at end-diastole, -2.8 ± 6.5 ml at end-systole). Agreement in contractility and compliance derived from conductance PV loop catheters and in the CMR environment was modest (intraclass correlation coefficient 0.56 and 0.44, respectively). CONCLUSIONS: Dynamic PV loops during a real-time CMR-guided preload reduction can be used to derive quantitative metrics of contractility and compliance, and provided more reliable volumetric measurements than conductance PV loop catheters.

Right transradial coronary angiography in the setting of tortuous brachiocephalic/thoracic aorta ("elephant head"): Impact on fluoroscopy time and contrast use.

OBJECTIVES: Assess the impact on fluoroscopy time and contrast use in patients with tortuous brachiocephalic/thoracic aortas undergoing right transradial coronary angiography (RTCA) and provide strategies to manage. BACKGROUND: Unfavorable anatomy with severe brachiocephalic/thoracic tortuosity, referred to as an "elephant head," remains a significant obstacle for RTCA. METHODS: We reviewed the coronary angiograms of patients who underwent RTCA and had tortuous aortas. Angiography was attempted first using a universal catheter (Tiger) and switched to a left coronary specific catheter (Judkins Left [JL]) if challenging. Fluoroscopy time, contrast volume, and greatest distance from the patient's midline to the catheter in the aorta were recorded. RESULTS: Forty-nine patients (62.6 ± 12.0 years, 69.4% male) were included. Fifteen (30.6%) patients underwent successful angiography with a Tiger catheter; 34 (69.4%) patients required switching to JL catheter. The average distance of Tiger catheters to the midline of the spine was 0.78 ± 0.41 cm versus 1.28 ± 0.44 cm (p = .001) in JL catheters. Tiger catheter use resulted in less fluoroscopy time (6.48 ± 4.73 min) and contrast use (58.87 ± 43.53 ml) than in cases switched to JL (13.26 ± 10.76 min [p = .026]; 86.5 ± 69.95 ml [(p = .017]). CONCLUSIONS: For patients undergoing RTCA with significant brachiocephalic/thoracic aorta tortuosity, "elephant head," a Tiger catheter can be used efficiently for curvatures <1 cm from the middle of the spine. We propose that for curvatures >1 cm, operators should consider immediately switching to a JL catheter.

National trends and 30-day readmission rates for next-day-discharge transcatheter aortic valve replacement: An analysis from the Nationwide Readmissions Database, 2012-2016.

Transcatheter aortic valve replacement (TAVR) has evolved toward a minimalist approach, resulting in shorter hospital stays. Real-world trends of next-day discharge (NDD) TAVR are unknown. This study aimed to evaluate underlying trends and readmissions of NDD TAVR. METHODS: This study was derived from the Nationwide Readmissions Database from 2012 to 2016. International Classification of Diseases, Ninth and Tenth Revisions, codes were used to identify patients. Any discharge within 1 day of admission was identified as NDD. NDD TAVR trends over the years were analyzed, and any admissions within 30 days were considered readmissions. A hierarchical logistic regression model was used to identify predictors of readmission. RESULTS: Of 49,742 TAVR procedures, 3,104 were NDD. The percentage of NDD TAVR increased from 1.5% (46/3,051) in 2012 to 12.2% (2,393/19,613) in 2016. However, the 30-day readmission rate remained the same over the years (8.6%). The patients' mean age was 80.3 ±â€¯8.4 years. Major readmission causes were heart-failure exacerbation (16%), infections (9%), and procedural complications (8%). In 2016, there were significantly higher late conduction disorder and gastrointestinal bleeding readmission rates than in 2012-2015. Significant predictors of readmission were anemia, baseline conduction disease, cardiac arrhythmias, heart failure, chronic kidney disease, chronic obstructive pulmonary disease, neoplastic disorders, and discharge to facility. CONCLUSIONS: The percentage of NDD TAVR increased over the years; however, readmission rates remained the same, with a higher rate of conduction abnormality-related hospitalizations in 2016. Careful discharge planning that includes identification of baseline factors that predict readmission and knowledge of etiologies may further prevent 30-day readmissions.

First-in-human transcatheter pledget-assisted suture tricuspid annuloplasty for severe tricuspid insufficiency.

OBJECTIVES: We report the first pledget-assisted suture tricuspid annuloplasty (PASTA) in a patient with torrential tricuspid regurgitation (TR). BACKGROUND: Tricuspid valve regurgitation is a common malignant disease with no commercially available transcatheter therapy. PASTA is a "percutaneous surgical" procedure using pledgeted sutures to create a double-orifice tricuspid valve. METHODS: An 83-year-old man had end-stage TR caused by a defibrillator lead. He consented to undergo PASTA on a compassionate basis. A double-orifice valve was created with pledgeted sutures from percutaneous right ventricular apical access. RESULTS: TR was reduced from torrential to trace. The vena contracta reduced to from 23 to 1 mm and annular area reduced from 1817 to 782 mm2 . However, the annulus dehisced and required closure with a percutaneous nitinol plug. The patient was discharged home and was alive 6 months later but with persistent symptoms. CONCLUSIONS: The anatomy of a double-orifice valve can eliminate TR but a better solution is required to avoid excessive suture tension on annular tissue.

Real-world experience of suture-based closure devices: Insights from the FDA Manufacturer and User Facility Device Experience.

OBJECTIVES: We analyzed post-marketing surveillance data from the United States Food and Drug Administration (FDA) Manufacturer and User Facility Device Experience (MAUDE) database for suture-based vascular closure devices (VCDs) - Perclose ProGlide (Abbott, Chicago, Illinois) and Prostar XL (Abbott). BACKGROUND: Suture-based VCDs are mostly used for large-bore femoral arterial access-site closure. Real-world, contemporary experience on the most commonly reported complications and modes of failure associated with these devices is limited. METHODS: Post-marketing surveillance data from the FDA MAUDE database, for the ProGlide system and for the Prostar XL system, were analyzed, yielding 827 Perclose ProGlide reports and 175 Prostar XL reports. RESULTS: Of the 827 reports of major complications involving the Perclose ProGlide devices, 404 reports involved injury, and one involved death related to the device. In the Prostar XL analysis, 94 reports involved injury, and one involved death. Bleeding from vessel injury was the most common adverse outcome described with both devices, followed by hematoma and thrombus. Surgical repair was the most commonly used treatment strategy. In terms of device malfunction, suture-related malfunction (212 reports) was most commonly seen in the Perclose ProGlide group, while failed deployment was most commonly seen in the Prostar XL group. CONCLUSIONS: Our analysis of the MAUDE database demonstrates that in real-world practice, suture-based VCDs were found to be associated with complications, including vascular injury, difficulties with the device itself, and even death. Ongoing user education and pre-procedural patient selection are important to minimize risks associated with suture-based vascular closure devices.

BATMAN-Savior or vigilante?

BATMAN is a new technique to prevent left ventricular outflow tract (LVOT) obstruction from transcatheter mitral valve replacement (TMVR) by deploying the transcatheter heart valve from the apex through a perforation of the anterior mitral valve leaflet. The risks of uncontrolled balloon dilatation of the anterior mitral valve leaflet include extension of the tear superiorly into the aorto-mitral curtain or laterally to avulse the trigone from the annulus. Percutaneous laceration of the anterior mitral leaflet, pre-emptive alcohol septal ablation, and transatrial leaflet resection are alternative strategies that prevent LVOT obstruction from TMVR.

Adverse events and modes of failure related to the FilterWire EZ Embolic Protection System: Lessons learned from an analytic review of the FDA MAUDE database.

OBJECTIVES: To assess the commonly reported complications and failure modes for FilterWire EZ Embolic Protection Devices (EPD) by analyzing the postmarketing surveillance data from the Food and Drug Administration (FDA) Manufacturer and User Facility Device Experience (MAUDE) database. BACKGROUND: EPDs prevent distal embolization of atheroembolic materials during percutaneous interventions resulting in reduced microvascular obstruction and improved microcirculation while maintaining tissue perfusion. The FilterWire EZ EPD (Boston Scientific, Natick, MA) is approved for use in interventions of de novo saphenous vein grafts (SVG) and carotid artery stenosis. Robust data on the commonly reported complications and failure modes associated with the FilterWire EZ device are limited. METHODS: The MAUDE database was queried from September 1, 2008, through September 30, 2018, for FilterWire EZ system, yielding 474 reports. After exclusion of duplicate and incomplete reports, 464 device reports were included in the final analysis. RESULTS: Device-related adverse events were most commonly reported for carotid (n = 281) and SVG (n = 101) interventions. The most commonly reported major complications were: ischemic stroke (n = 57), vessel perforation or dissection (n = 12), death (n = 8), and myocardial infarction (n = 5). Minor complications included: hypotension (n = 68), bradycardia (n = 41), and vasospasm (n = 27). The most commonly reported failure modes were: detachment and/or damage of the device components (n = 118), device entrapment (n = 90), and stent-related issues (n = 46). CONCLUSIONS: Analysis of the MAUDE dataset is helpful in identifying the commonly reported adverse events and failure modes of FilterWire EZ devices. This platform serves as an important tool for both physicians and manufacturers to optimize device performance and clinical outcomes.

Transcatheter electrosurgery in bipolar or monopolar modes.

Transcatheter electrosurgery has emerging value in a range of other new procedures that require traversing tissue (transcaval access, transcatheter Glenn Shunt) or slicing tissue (LAMPOON slicing of the mitral valve and BASILICA slicing of the aortic valve). This is the first report of bipolar radiofrequency wires used to cross lesions in humans, reported here in seven re-entry CTO cases. The bipolar configuration may provide directionality to charge without need for wire alignment and advancement, but is theoretically disadvantageous for tissue "cutting" because of problems with charge concentration.

Guidewire electrosurgery-assisted trans-septal puncture.

OBJECTIVES: Electrifying a coronary guidewire may be a simple escalation strategy when trans-septal needle puncture is unsuccessful. BACKGROUND: Radiofrequency energy to facilitate trans-septal puncture through a dedicated device is costly and directly through a trans-septal needle may be less safe. Our technique overcomes these limitations. METHODS: The technique was used in patients when trans-septal needle penetration failed despite excessive force or tenting of the atrial septum. A coronary guidewire, connected to an electrosurgery pencil, was advanced through the trans-septal needle, dilator, and sheath to perforate the interatrial septum during a short burst of radiofrequency energy. With the guidewire tip no longer "active," the dilator and sheath were advanced safely over the wire into the left atrium. In posthoc validation, radiofrequency assisted Brockenbrough needle and coronary guidewire punctures were made in freshly explanted pig hearts and compared under microscopy. RESULTS: Eight patients who required trans-septal access for structural intervention were escalated to a guidewire electrosurgery strategy. Six patients had thickened fibrotic septum and two had prior surgical patch repair. Crossing was successful in all patients with no procedure related complications. The size of punctures (1.11 ± 0.40 mm vs 0.37 ± 0.08 mm, P = .009) and blanched penumbra (3.62 ± 1.23 mm vs 0.72 ± 0.29 mm, P = .003) in pig atrial septum were larger with an electrified needle than electrified guidewire. The hole generated by the electrified guidewire was smaller than by the nonelectrified needle. CONCLUSIONS: When conventional trans-septal puncture fails, a coronary guidewire can be used to deliver brief radiofrequency energy safely and effectively. This technique is inexpensive and accessible to operators.

Transcatheter pledget-assisted suture tricuspid annuloplasty (PASTA) to create a double-orifice valve.

OBJECTIVES: Pledget-assisted suture tricuspid valve annuloplasty (PASTA) is a novel technique using marketed equipment to deliver percutaneous trans-annular sutures to create a double-orifice tricuspid valve. BACKGROUND: Tricuspid regurgitation is a malignant disease with high surgical mortality and no commercially available transcatheter solution in the US. METHODS: Two iterations of PASTA were tested using trans-apical or trans-jugular access in swine. Catheters directed paired coronary guidewires to septal and lateral targets on the tricuspid annulus under fluoroscopic and echocardiographic guidance. Guidewires were electrified to traverse the annular targets and exchanged for pledgeted sutures. The sutures were drawn together and knotted, apposing septal and lateral targets, creating a double orifice tricuspid valve. RESULTS: Twenty-two pigs underwent PASTA. Annular and chamber dimensions were reduced (annular area, 10.1 ± 0.8 cm2 to 3.8 ± 1.5 cm2 (naïve) and 13.1 ± 1.5 cm2 to 6.2 ± 1.0 cm2 (diseased); septal-lateral diameter, 3.9 ± 0.3 mm to 1.4 ± 0.6 mm (naïve) and 4.4 ± 0.4 mm to 1.7 ± 1.0 mm (diseased); and right ventricular end-diastolic volume, 94 ± 13 ml to 85 ± 14 ml (naïve) and 157 ± 25 ml to 143 ± 20 ml (diseased)). MRI derived tricuspid regurgitation fraction fell from 32 ± 12% to 4 ± 5%. Results were sustained at 30 days. Pledget pull-through force was five-fold higher (40.6 ± 11.7N vs 8.0 ± 2.6N, P < .01) using this strategy compared to single puncture techniques used to anchor current investigational devices. Serious complications were related to apical access. CONCLUSIONS: PASTA reduces annular dimensions and tricuspid regurgitation in pigs. It may be cautiously applied to selected patients with severe tricuspid regurgitation and no options. This is the first transcatheter procedure, to our knowledge, to deliver standard pledgeted sutures to repair cardiac pathology.

Blood volume measurement using cardiovascular magnetic resonance and ferumoxytol: preclinical validation.

BACKGROUND: The hallmark of heart failure is increased blood volume. Quantitative blood volume measures are not conveniently available and are not tested in heart failure management. We assess ferumoxytol, a marketed parenteral iron supplement having a long intravascular half-life, to measure the blood volume with cardiovascular magnetic resonance (CMR). METHODS: Swine were administered 0.7 mg/kg ferumoxytol and blood pool T1 was measured repeatedly for an hour to characterize contrast agent extraction and subsequent effect on Vblood estimates. We compared CMR blood volume with a standard carbon monoxide rebreathing method. We then evaluated three abbreviated acquisition protocols for bias and precision. RESULTS: Mean plasma volume estimated by ferumoxytol was 61.9 ± 4.3 ml/kg. After adjustment for hematocrit the resultant mean blood volume was 88.1 ± 9.4 ml/kg, which agreed with carbon monoxide measures (91.1 ± 18.9 ml/kg). Repeated measurements yielded a coefficient of variation of 6.9%, and Bland-Altman repeatability coefficient of 14%. The blood volume estimates with abbreviated protocols yielded small biases (mean differences between 0.01-0.06 L) and strong correlations (r2 between 0.97-0.99) to the reference values indicating clinical feasibility. CONCLUSIONS: In this swine model, ferumoxytol CMR accurately measures plasma volume, and with correction for hematocrit, blood volume. Abbreviated protocols can be added to diagnostic CMR examination for heart failure within 8 min.

Right heart catheterization using metallic guidewires and low SAR cardiovascular magnetic resonance fluoroscopy at 1.5 Tesla: first in human experience.

BACKGROUND: Cardiovascular magnetic resonance (CMR) fluoroscopy allows for simultaneous measurement of cardiac function, flow and chamber pressure during diagnostic heart catheterization. To date, commercial metallic guidewires were considered contraindicated during CMR fluoroscopy due to concerns over radiofrequency (RF)-induced heating. The inability to use metallic guidewires hampers catheter navigation in patients with challenging anatomy. Here we use low specific absorption rate (SAR) imaging from gradient echo spiral acquisitions and a commercial nitinol guidewire for CMR fluoroscopy right heart catheterization in patients. METHODS: The low-SAR imaging protocol used a reduced flip angle gradient echo acquisition (10° vs 45°) and a longer repetition time (TR) spiral readout (10 ms vs 2.98 ms). Temperature was measured in vitro in the ASTM 2182 gel phantom and post-mortem animal experiments to ensure freedom from heating with the selected guidewire (150 cm × 0.035″ angled-tip nitinol Terumo Glidewire). Seven patients underwent CMR fluoroscopy catheterization. Time to enter each chamber (superior vena cava, main pulmonary artery, and each branch pulmonary artery) was recorded and device visibility and confidence in catheter and guidewire position were scored on a Likert-type scale. RESULTS: Negligible heating (< 0.07°C) was observed under all in vitro conditions using this guidewire and imaging approach. In patients, chamber entry was successful in 100% of attempts with a guidewire compared to 94% without a guidewire, with failures to reach the branch pulmonary arteries. Time-to-enter each chamber was similar (p=NS) for  the two approaches. The guidewire imparted useful catheter shaft conspicuity and enabled interactive modification of catheter shaft stiffness, however, the guidewire tip visibility was poor. CONCLUSIONS: Under specific conditions, trained operators can apply low-SAR imaging and using a specific fully-insulated metallic nitinol guidewire (150 cm × 0.035" Terumo Glidewire) to augment clinical CMR fluoroscopy right heart catheterization. TRIAL REGISTRATION: Clinicaltrials.gov NCT03152773 , registered May 15, 2017.

Unnatural milieu: Thrombus after transcatheter mitral valve replacement.

What the article teaches Transcatheter heart valve thrombosis in the mitral position causes increased valve gradients, valve dysfunction, and symptoms, and may be associated with lack of therapeutic anticoagulation. How it will impact practice Anticoagulation with a vitamin K antagonist should be considered in all patients undergoing transcatheter mitral valve replacement. What new research/study would help answer the question posed Efficacy, optimal duration, and safety of anticoagulation therapy, balancing reduced thrombosis against increased bleeding risk, needs to be assessed in larger cohort studies and prospective trials.

CMR fluoroscopy right heart catheterization for cardiac output and pulmonary vascular resistance: results in 102 patients.

BACKGROUND: Quantification of cardiac output and pulmonary vascular resistance (PVR) are critical components of invasive hemodynamic assessment, and can be measured concurrently with pressures using phase contrast CMR flow during real-time CMR guided cardiac catheterization. METHODS: One hundred two consecutive patients underwent CMR fluoroscopy guided right heart catheterization (RHC) with simultaneous measurement of pressure, cardiac output and pulmonary vascular resistance using CMR flow and the Fick principle for comparison. Procedural success, catheterization time and adverse events were prospectively collected. RESULTS: RHC was successfully completed in 97/102 (95.1%) patients without complication. Catheterization time was 20 ± 11 min. In patients with and without pulmonary hypertension, baseline mean pulmonary artery pressure was 39 ± 12 mmHg vs. 18 ± 4 mmHg (p < 0.001), right ventricular (RV) end diastolic volume was 104 ± 64 vs. 74 ± 24 (p = 0.02), and RV end-systolic volume was 49 ± 30 vs. 31 ± 13 (p = 0.004) respectively. 103 paired cardiac output and 99 paired PVR calculations across multiple conditions were analyzed. At baseline, the bias between cardiac output by CMR and Fick was 5.9% with limits of agreement -38.3% and 50.2% with r = 0.81 (p < 0.001). The bias between PVR by CMR and Fick was -0.02 WU.m2 with limits of agreement -2.6 and 2.5 WU.m2 with r = 0.98 (p < 0.001). Correlation coefficients were lower and limits of agreement wider during physiological provocation with inhaled 100% oxygen and 40 ppm nitric oxide. CONCLUSIONS: CMR fluoroscopy guided cardiac catheterization is safe, with acceptable procedure times and high procedural success rate. Cardiac output and PVR measurements using CMR flow correlated well with the Fick at baseline and are likely more accurate during physiological provocation with supplemental high-concentration inhaled oxygen. TRIAL REGISTRATION: Clinicaltrials.gov NCT01287026 , registered January 25, 2011.

Non-invasive pressure-volume loops using the elastance model and CMR: a porcine validation at transient pre-loads.

Aims: Pressure-volume (PV) loops have utility in the evaluation of cardiac pathophysiology but require invasive measurements. Recently, a time-varying elastance model to derive PV loops non-invasively was proposed, using left ventricular (LV) volume by cardiovascular magnetic resonance (CMR) and brachial cuff pressure as inputs. Validation was performed using CMR and pressure measurements acquired on the same day, but not simultaneously, and without varying pre-loads. This study validates the non-invasive elastance model used to estimate PV loops at varying pre-loads, compared with simultaneous measurements of invasive pressure and volume from real-time CMR, acquired concurrent to an inferior vena cava (IVC) occlusion. Methods and results: We performed dynamic PV loop experiments under CMR guidance in 15 pigs (n = 7 naïve, n = 8 with ischaemic cardiomyopathy). Pre-load was altered by IVC occlusion, while simultaneously acquiring invasive LV pressures and volumes from real-time CMR. Pairing pressure and volume signals yielded invasive PV loops, and model-based PV loops were derived using real-time LV volumes. Haemodynamic parameters derived from invasive and model-based PV loops were compared. Across 15 pigs, 297 PV loops were recorded. Intra-class correlation coefficient (ICC) agreement was excellent between model-based and invasive parameters: stroke work (bias = 0.007 ± 0.03 J, ICC = 0.98), potential energy (bias = 0.02 ± 0.03 J, ICC = 0.99), ventricular energy efficiency (bias = -0.7 ± 2.7%, ICC = 0.98), contractility (bias = 0.04 ± 0.1 mmHg/mL, ICC = 0.97), and ventriculoarterial coupling (bias = 0.07 ± 0.15, ICC = 0.99). All haemodynamic parameters differed between naïve and cardiomyopathy animals (P < 0.05). The invasive vs. model-based PV loop dice similarity coefficient was 0.88 ± 0.04. Conclusion: An elastance model-based estimation of PV loops and associated haemodynamic parameters provided accurate measurements at transient loading conditions compared with invasive PV loops.

Ventricular Intramyocardial Navigation for Tachycardia Ablation Guided by Electrograms (VINTAGE): Deep Ablation in Inaccessible Targets.

BACKGROUND: Deep intramural ventricular tachycardia substrate targets are difficult to access, map, and ablate from endocardial and epicardial surfaces, resulting in high recurrence rates. OBJECTIVES: In this study, the authors introduce a novel approach called ventricular intramyocardial navigation for tachycardia ablation guided by electrograms (VINTAGE) to access and ablate anatomically challenging ventricular tachycardia from within the myocardium. METHODS: Guidewire/microcatheter combinations were navigated deep throughout the extravascular myocardium, accessed directly from the right ventricle cavity, in Yorkshire swine (6 naive, 1 infarcted). Devices were steered to various intramyocardial targets including the left ventricle summit, guided by fluoroscopy, unipolar electrograms, and/or electroanatomic mapping. Radiofrequency ablations were performed to characterize ablation parameters and reproducibility. Intramyocardial saline irrigation began 1 minute before ablation and continued throughout. Lesions were analyzed on cardiac magnetic resonance and necropsy. RESULTS: VINTAGE was feasible in all animals within naive and infarcted myocardium. Forty-three lesions were created, using various guidewires and power settings. Forty-one (95%) lesions were detected on cardiac magnetic resonance and 38 (88%) on necropsy; all undetected lesions resulted from intentionally subtherapeutic ablation energy (10 W). Larger-diameter guidewires yielded larger size lesions. Lesion volumes on necropsy were significantly larger at 20 W than 10 W (178 mm3 [Q1-Q3: 104-382 mm3] vs 49 mm3 [Q1-Q3: 35-93 mm3]; P = 0.02). Higher power (30 W) did not create larger lesions. Median impedance dropped with preablation irrigation by 12 Ω (Q1-Q3: 8-17 Ω), followed by a further 15-Ω (Q1-Q3: 11-19 Ω) drop during ablation. Intramyocardial navigation, ablation, and irrigation were not associated with any complications. CONCLUSIONS: VINTAGE was safe and effective at creating intramural ablation lesions in targets traditionally considered inaccessible from the endocardium and epicardium, both naive and infarcted. Intramyocardial guidewire irrigation and ablation at 20 W creates reproducibly large intramural lesions.

TABERNACL: Temporary Hemodynamic Stabilization In Vivo.

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.