Noninvasive Left Ventricle Pressure-Volume Loop Determination Method with Cardiac Magnetic Resonance Imaging and Carotid Tonometry Using a Physics-Informed Approach.

Left ventricular (LV) pressure-volume loop (PV-loop) is an important tool to quantify intrinsic left ventricular properties and ventricular-arterial coupling. A significant drawback of conventional PV-loop assessment is the need of invasive measurements which limits its widespread application. To tackle this issue, we developed a PV-loop determination method by using non-invasive measurements from arterial tonometry and cardiac magnetic resonance imaging. A physics-based optimization strategy was designed that adaptively identifies the optimal parameters to construct the PV-loop. We conducted comparative analysis in a convenience sample (N = 77) with heart failure (HF) (N = 23) patients and a control (N = 54) group to evaluate the sensitivity our PV-loop estimation algorithm. Significant and coherent differences between cohorts for the parameters derived using the PV-loop were observed. Our method captures the significant elevation of LV end diastolic pressure (p<0.001), and the decrease of the ventricular efficiency (p<0.0001) of the HF patients compared to the Control group. This method further captures the mechanistic changes of the LV by highlighting the significant differences of the smaller stroke work (p<0.0001), mean external power (p<0.05), and contractility (p<0.001) between these groups. The LV performance metrics align well with the previous clinical PV-loop observations of HF patients and our results demonstrate that the proposed PV-loop reconstruction method can be used to assess the ventricular functional changes associated with HF. Using this noninvasive method may significantly impact and facilitate the diagnosis and therapeutic management of HF.

Abnormal left atrial body stiffness is predicted by appendage size: impact of appendage occlusion on left atrial mechanics assessed by pressure-volume analysis.

Atrial cardiomyopathy has been recognized as having important consequences for cardiac performance and clinical outcomes. The pathophysiological role of the left atrial (LA) appendage and the effect of percutaneous left atrial appendage occlusion (LAAO) upon LA mechanics is incompletely understood. We evaluated if changes in LA stiffness due to endocardial LAAO can be detected by LA pressure-volume (PV) analysis and whether stiffness parameters are associated with baseline characteristics. Patients undergoing percutaneous endocardial LAAO (n = 25) were studied using a novel PV analysis using near-simultaneous three-dimensional LA volume measurements by transesophageal echocardiography (TEE) and direct invasive LA pressure measurements. LA stiffness (dP/dV, change in pressure with change in volume) was calculated before and after LAAO. Overall LA stiffness significantly increased after LAAO compared with baseline (median, 0.41-0.64 mmHg/mL; P ≪ 0.001). LA body stiffness after LAAO correlated with baseline LA appendage size by indexed maximum depth (Spearman's rank correlation coefficient Rs = 0.61; P < 0.01). LA stiffness change showed an even stronger correlation with baseline LA appendage size by indexed maximum depth (Rs = 0.70; P < 0.001). We found that overall LA stiffness increases after endocardial LAAO. Baseline LA appendage size correlates with the magnitude of increase and LA body stiffness. These findings document alteration of LA mechanics after endocardial LAAO and suggest that the LA appendage modulates overall LA compliance.NEW & NOTEWORTHY Our study documents a correlation of LA appendage remodeling with the degree of chronically abnormal LA body stiffness. In addition, we found that LA appendage size was the baseline parameter that best correlated with the magnitude of a further increase in overall LA stiffness after appendage occlusion. These findings offer insights about the LA appendage and LA mechanics that are relevant to patients at risk for adverse atrial remodeling, especially candidates for LA appendage occlusion.

Changes in left atrial appendage orifice following percutaneous left atrial appendage closure using three-dimensional echocardiography.

Percutaneous left atrial appendage (LAA) occlusion is increasingly performed in patients with atrial fibrillation and long-term contraindications for anticoagulation. Our aim was to evaluate the effects of LAA occlusion with the Watchman device on the geometry of the LAA orifice and assess its impact on the adjacent left upper pulmonary vein (LUPV) hemodynamics. We included 50 patients who underwent percutaneous LAA occlusion with the Watchman device and had acceptable three-dimensional transesophageal echocardiography images of LAA pre- and post-device placement. We measured offline the LAA orifice diameters in the long axis, and the minimum and maximum diameters, circumference, and area in the short axis view. Eccentricity index was calculated as maximum/minimum diameter ratio. The LUPV peak S and D velocities pre- and post-procedure were also measured. Patients were elderly (mean age 76 ± 8 years), 30 (60%) were men. There was a significant increase of all LAA orifice dimensions following LAA occlusion: diameter 1 (pre-device 18.1 ± 3.2 vs. post-device 21.5 ± 3.4 mm, p < 0.001), diameter 2 (20.6 ± 3.9 vs. 22.1 ± 3.6 mm, p < 0.001), minimum diameter (17.6 ± 3.1 vs. 21.3 ± 3.4 mm, p < 0.001), maximum diameter (21.5 ± 3.9 vs. 22.4 ± 3.6 mm, p = 0.022), circumference (63.6 ± 10.7 vs. 69.6 ± 10.5 mm, p < 0.001), and area (3.1 ± 1.1 vs. 3.9 ± 1.2 cm2, p < 0.001). Eccentricity index decreased after procedure (1.23 ± 0.16 vs. 1.06 ± 0.06, p < 0.001). LUPV peak S and D velocities did not show a significant difference (0.29 ± 0.15 vs. 0.30 ± 0.14 cm/s, p = 0.637; and 0.47 ± 0.19 vs. 0.48 ± 0.20 cm/s, p = 0.549; respectively). LAA orifice stretches significantly and it becomes more circular following LAA occlusion without causing a significant impact on the LUPV hemodynamics.

ISL1 cardiovascular progenitor cells for cardiac repair after myocardial infarction.

Cardiovascular progenitor cells (CPCs) expressing the ISL1-LIM-homeodomain transcription factor contribute developmentally to cardiomyocytes in all 4 chambers of the heart. Here, we show that ISL1-CPCs can be applied to myocardial regeneration following injury. We used a rapid 3D methylcellulose approach to form murine and human ISL1-CPC spheroids that engrafted after myocardial infarction in murine hearts, where they differentiated into cardiomyocytes and endothelial cells, integrating into the myocardium and forming new blood vessels. ISL1-CPC spheroid-treated mice exhibited reduced infarct area and increased blood vessel formation compared with control animals. Moreover, left ventricular (LV) contractile function was significantly better in mice transplanted with ISL1-CPCs 4 weeks after injury than that in control animals. These results provide proof-of-concept of a cardiac repair strategy employing ISL1-CPCs that, based on our previous lineage-tracing studies, are committed to forming heart tissue, in combination with a robust methylcellulose spheroid-based delivery approach.

Contour tracking in echocardiographic sequences via sparse representation and dictionary learning.

This paper presents a dynamical appearance model based on sparse representation and dictionary learning for tracking both endocardial and epicardial contours of the left ventricle in echocardiographic sequences. Instead of learning offline spatiotemporal priors from databases, we exploit the inherent spatiotemporal coherence of individual data to constraint cardiac contour estimation. The contour tracker is initialized with a manual tracing of the first frame. It employs multiscale sparse representation of local image appearance and learns online multiscale appearance dictionaries in a boosting framework as the image sequence is segmented frame-by-frame sequentially. The weights of multiscale appearance dictionaries are optimized automatically. Our region-based level set segmentation integrates a spectrum of complementary multilevel information including intensity, multiscale local appearance, and dynamical shape prediction. The approach is validated on twenty-six 4D canine echocardiographic images acquired from both healthy and post-infarct canines. The segmentation results agree well with expert manual tracings. The ejection fraction estimates also show good agreement with manual results. Advantages of our approach are demonstrated by comparisons with a conventional pure intensity model, a registration-based contour tracker, and a state-of-the-art database-dependent offline dynamical shape model. We also demonstrate the feasibility of clinical application by applying the method to four 4D human data sets.

Cryoballoon ablation for atrial fibrillation guided by real-time three-dimensional transoesophageal echocardiography: a feasibility study.

AIMS: Cryoballoon ablation (CBA; Arctic Front, Medtronic) has proven very effective in achieving pulmonary vein isolation. Real-time three-dimensional transoesophageal echocardiography (RT 3D TEE) is a novel technology, which permits detailed visualization of cardiac structures in a 3D perspective. The aim of the present study was to assess the feasibility, advantages, and safety of RT 3D TEE in guiding CBA in a series of patients affected by paroxysmal atrial fibrillation. METHODS AND RESULTS: Forty-five patients (34 males, mean age: 63 ± 12 years) underwent CBA guided by 3D TEE. A total of 190 veins could be documented by TEE. Real-time three-dimensional transoesophageal echocardiography successfully guided the operator to position the CB in the pulmonary vein (PV) ostium and obtain complete occlusion in all 190 (100%) veins. Transoesophageal echocardiography identified leakages in 25 (13%) veins led to successful elimination of PV-left atrium (LA) backflow by guiding correct balloon repositioning. In four (2%) veins, this imaging tool led to perform successful pull-down manoeuvres. After a mean 2.6 ± 1.4 applications, isolation could be documented in 190 (100%) PVs. Median procedural and fluoroscopy times were 145 and 24 min. During a median follow-up of 278 days, 37 (82%) patients did not experience atrial fibrillation recurrence following a 3-month blanking period. CONCLUSION: Cryoballoon ablation is safe and feasible under RT 3D TEE guidance. This imaging tool permits perfect visualization of all PV ostia and neighbouring LA structures. Most importantly, it proved very efficient in guiding the operator to achieve complete occlusion and successful isolation in all veins.

Segmentation of 4D echocardiography using stochastic online dictionary learning.

Dictionary learning has been shown to be effective in exploiting spatiotemporal coherence for echocardiographic segmentation. To overcome the limitations of previous methods, we present a stochastic online dictionary learning approach for segmenting left ventricular borders from 4D echocardiography. It is based on stochastic approximations and processes a mini-batch of samples at a time, which results in lower memory consumption and lower computational cost than classical batch algorithms. In contrast to the previous methods, where dictionaries and their weights are optimized only on the most recently segmented frame, our stochastic online learning procedure optimizes the dictionaries and the corresponding weights by aggregating all the past information while adapting them to the dynamically changing data. The rate of updating the past information is controlled and varied according to the appearance scale to seek a balance between old and new information. Results on 26 4D echocardiographic images show the proposed method is more accurate, more robust, and faster than the previous batch algorithm.

TachoSil for postinfarction ventricular free wall rupture.

Despite a decline in the last three decades, postinfarction ventricular free wall rupture still complicates more than 3% of acute ST-elevation myocardial infarctions and remains a surgical challenge. TachoSil (Nycomed, Zurich, Switzerland) is an equine collagen patch coated with human fibrinogen and human thrombin, which has recently been used for haemostasis in cardiovascular surgery, but its potential usefulness in free wall rupture has not been reported. Initial clinical experience with an on-pump sutureless technique without cardioplegia, using wide TachoSil patching to achieve free wall rupture repair, has been described.

Coronary artery bypass graft and mitral valvuloplasty in a patient with isolated ventricular non-compaction.

A case of isolated ventricular non-compaction associated to three-vessel disease and a mitral regurgitation is described. The patient underwent triple coronary artery bypass graft and restrictive mitral annuloplasty. The postoperative course was unsuccessful despite the very depressed left ventricular (LV) function. At two years follow-up, no major adverse cardiac event has occurred and the LV function was slightly improved.

Low-risk profile for malignant ventricular arrhythmias and sudden cardiac death after surgical ventricular reconstruction.

BACKGROUND: Although it has been recently demonstrated that there was no significant difference in total survival and clinical outcomes between patients who underwent coronary artery bypass grafting (CABG) with or without surgical ventricular reconstruction (SVR), the question of whether or not SVR decreases the arrhythmic risk profile in this population has not been clarified yet. OBJECTIVE: To determine the real incidence of sudden cardiac death (SCD) and sustained ventricular tachycardia/ventricular fibrillation (sustained VT/VF) in patients following CABG added to SVR and to define their clinical and echocardiographic parameters predicting in-hospital and long-term arrhythmic events (SCD + sustained VT/VF). METHODS: Pre- and postoperative clinical and echocardiographic values as well as postoperative electrocardiogram Holter data of 65 patients (21 female, 63 ± 11 years) who underwent SVR + CABG were retrospectively evaluated. RESULTS: Mean follow-up was 1,105 ± 940 days. At 3 years, the SCD-free rate was 98% and the rate free from arrhythmic events was 88%. Multivariate logistic analysis identified a preoperative left ventricular end-systolic volume index (LVESVI) > 102 mL/m(2) (odds ratio [OR] 1.4, confidence interval [CI] 1.073-1.864, P = 0.02; sensitivity 100%, specificity 94%) and a postoperative pulmonary artery systolic pressure (PASP) > 27 mmHg (OR 2.3, CI 1.887-4.487, P = 0.01; sensitivity 100%, specificity 71%) as independent predictors of arrhythmic events. CONCLUSIONS: Our and previous studies report a low incidence of arrhythmic events in patients following SVR added to CABG, considering the high-risk profile of the study population. A preoperative LVESVI > 102 mL/m(2) and a postoperative PASP > 27 mmHg had a good sensitivity and specificity in predicting arrhythmic events.

Predictors of adverse events after surgical ventricular restoration for advanced ischaemic cardiomyopathy.

OBJECTIVE: Post-infarction ventricular remodelling has been graded (I-III) according to the loss of systolic left ventricular silhouette curvature changes. Although surgical ventricular restoration (SVR) has been extended to type III ischaemic cardiomyopathy, the results are less satisfactory. We sought to identify geometric and functional predictors of late outcome after SVR. METHODS: Among 144 patients who underwent SVR since 1998, a subgroup of 31 patients (age: 65.2+/-7.6 years) was analysed. Inclusion criteria were: type III cardiomyopathy, no associated procedure except coronary artery bypass grafting, prior anterior infarction, absent-to-2+ mitral regurgitation, elective operation, follow-up > or =18 months (mean: 44+/-26; longest: 96 months). Probability of events was estimated with the Kaplan-Meier method. A Cox multivariable regression model was constructed selecting eight potential predictors of four adverse events: death, cardiac death, recurrent heart failure (New York Heart Association class III or IV) and left ventricular re-remodelling, defined as a 25% increase of end-systolic volume index after SVR, or an end-systolic volume index > or =50 ml.m(-2). RESULTS: Early and late mortality were zero and 6% (2/31 patients, one cardiac-related death). NYHA class and all echocardiographic functional variables significantly improved early after SVR. Freedom (+/-standard error (SE)) from heart failure was 97%+/-3%, 93%+/-5%, 77%+/-11% and 64%+/-15%, whereas freedom from left ventricular re-remodelling was 97%+/-3%, 80%+/-8%, 60%+/-12% and 39%+/-15%, respectively, 1, 3, 5 and 7 years after SVR. Multivariable analysis identified baseline mitral regurgitation degree and sphericity index as independent predictors of recurrent heart failure (p=0.025; hazard ratio (HR)=7.80 (95% confidence intervals (CIs): 1.29-47.19)) and left ventricular re-remodelling (p=0.047; HR=2.84 (95% CIs: 1.01-7.95)). Both predictors also correlated with a higher recurrence of end-systolic volume index > or =50 ml.m(-2) at late follow-up. CONCLUSIONS: Despite advanced cardiomyopathy, SVR determines left ventricular volume reduction and improved systolic function. Baseline absent-to-moderate mitral regurgitation and a more spherical left ventricular geometry predict a less favourable clinical and functional outcome, suggesting a possible rationale for wider indications for combined correction of 2+ mitral regurgitation and undersizing of the mitral annulus, particularly in patients with sphericity index > or =0.75.

Baseline left ventricular function and surgical annular stiffening to predict outcome and reverse left ventricular remodeling after undersized annuloplasty for intermediate-degree ischemic mitral regurgitation.

OBJECTIVE: We sought to identify determinants of clinical and functional outcome after myocardial revascularization and associated undersized annuloplasty in patients with intermediate-degree ischemic mitral regurgitation. METHODS: Fifty-seven patients with 2+ or 3+ ischemic mitral regurgitation underwent coronary bypass surgery and implantation of undersized semirigid or flexible complete ring or autologous pericardial band and were followed up to 8.6 years. RESULTS: Operative mortality was 5%. Baseline left ventricular end-systolic volume index, the strongest multivariable predictor of early postoperative outcome, was correlated with end-systolic volume index (P < .001, R(2) = 0.67) and ejection fraction (P < .001, R(2) = 0.40) after repair. More compromised ejection fraction and end-systolic volume index predicted comparatively greater early functional improvement but higher residual postoperative end-systolic volume index (P < .01). Cox multivariable analysis identified wall motion as the best baseline predictor of late death and heart failure and regional inferoposterior wall motion as the strongest predictor of recurrent mitral regurgitation (P < or = .01). More rigid annuloplasty carried a higher probability of functional recovery in terms of ejection fraction, wall motion, and the occurrence and earlier timing of left ventricular reverse remodeling, expressed by different degrees of end-systolic volume index reduction (P < .001, hazard ratio >6). CONCLUSIONS: Combination of undersized mitral annuloplasty and coronary revascularization presents low operative mortality and determines left ventricular unloading in patients with intermediate-degree ischemic mitral regurgitation. Global and regional wall motion are powerful predictors of late outcome. Stiffer mitral annular repair promotes functional recovery and predicts higher probability and earlier timing of reverse remodeling.

Ejection fraction/velocity ratio identifies prosthesis-patient mismatches in patients with aortic bioprosthetic valves and left ventricular dysfunction.

OBJECTIVES: Recently, a new echocardiographic nonflow corrected index (ejection fraction/velocity ratio [EFVR] = percent left ventricular ejection fraction [EF]/maximum aortic gradient) has been introduced and has shown excellent accuracy in quantifying the effective orifice area (EOA) in native aortic valves and bio-prostheses. The objective of this study was to assess the utility of the EFVR to quantify the indexed EOA in patients with an aortic bioprosthesis and left ventricular dysfunction considering an indexed EOA value of 0.85 cm(2)/m(2) or less to be indicative of a prosthesis-patient mismatch (PPM), defined as an EOA of the inserted prosthetic valve of less than that of the normal human valve. METHODS: We studied 100 patients (62 men and 38 women; mean age +/- SD, 71 +/- 8.6 years) with an aortic bioprosthesis and left ventricular dysfunction (EF < or =49%), and we evaluated the indexed EOA by both the continuity equation (CE) and EFVR. RESULTS: We found a significant linear correlation between the CE and EFVR (r = 0.85; P < .0001) and good agreement between the two methods in identifying patients with an indexed EOA of 0.85 cm(2)/m(2) or less; the correlation began to become nonlinear for patients with an indexed EOA of greater than 1.2 cm(2)/m(2), which was not clinically relevant. Notably, all 11 patients with a discrepancy between the indexed EOA and EFVR (ie, EFVR < or =1.0 and indexed EOA >0.85 cm(2)/m(2)) also showed an indexed EOA of greater than 0.85 but less than or equal to 1.0 cm(2)/m(2) (meaning the presence of a mild PPM). CONCLUSIONS: The EFVR can be considered a reliable echocardiographic alternative to the CE, especially in conditions in which that is technically difficult, allowing identification of a PPM (indexed EOA < or =0.85 cm(2)/m(2)) with excellent sensitivity and specificity.