A new surgical ventricular restoration technique to reset residual myocardium's fiber orientation: the "KISS" procedure

Advances in Surgical Treatments of Left Ventricular Aneurysms

Despite improvements in the early intervention of myocardial infarction (MI) in recent decades, left ventricular aneurysms (LVA) remain a major health concern, particularly in developing nations. The progression of MI can lead to the thinning of the myocardial wall and the formation of a ventricular wall bulge, characteristic of an LVA. Furthermore, cardiac magnetic resonance (CMR) has emerged as the gold standard for LVA diagnosis due to its superior imaging capabilities. Notably, surgical ventricular reconstruction (SVR) is an effective treatment for LVA, aiming to restore the normal volume and structure of the left ventricle, thereby improving cardiac function. However, the criteria for selecting patients for SVR treatment remains a subject of debate. This review focuses on the current understanding of surgical indications, procedures, and prognostic risk factors that influence outcomes in left ventricular reconstruction, highlighting the need for precise patient selection to optimize surgical benefits.

The Memory of the Heart

The embryological development of the heart is one of the most fascinating phenomena in nature and so is its final structure and function. The various ontogenetic passages form the evolutive basis of the final configuration of the heart. Each key step can be recognized in the final features, as the heart maintains a kind of “memory” of these passages. We can identify the major lines of development of the heart and trace these lines up to the mature organ. The aim of this review is to identify these key parameters of cardiac structure and function as essential elements of the heart’s proper functioning and bases for its treatment. We aim to track key steps of heart development to identify what it “remembers” and maintains in its final form as positively selected. A new vision based on the whole acquired knowledge must guide an in-depth scientific approach in future papers and guidelines on the topic and a complete, farsighted therapeutic conduct able to ensure the physiological correction of cardiac pathologies. The application of this modern, functional vision of the heart could improve the clinical treatment of heart disease, filling the gaps still present.

Time series analysis of physiologic left ventricular reconstruction in ischemic cardiomyopathy

OBJECTIVE

The history of left ventricular reconstruction has demonstrated that the full spectrum of recoverable physiologic parameters is essential for a good functional result. We report the long-term outcome of a new surgical technique that arranges myocardial fibers in a near-normal disposition, also recovering left ventricular twisting.

METHODS

Between May 2006 and October 2013, 29 consecutive patients with previous anterior myocardial infarction and heart failure symptoms underwent physiologic left ventricular reconstruction surgery and coronary revascularization. Patients were examined by means of standard echocardiography and 2-dimensional speckle tracking at 8 time steps until 7 years after surgery. Ten geometric and functional parameters were evaluated at each step and analyzed by the linear mixed model test.

RESULTS

Hospital mortality was 0%. The mean percentage of indexed end-diastolic and end-systolic volume reduction was 45.7% and 50.9%, respectively. Ejection fraction and all of the volumes were significantly different in the postoperative period with a steady correction during time. Diastolic parameters were not worsened by surgical reconstruction. Ejection fraction and deceleration time showed a significant improvement during time. Left ventricular torsion increased immediately after the surgical correction from 2.8 ± 4.4 degrees to 8.7 ± 3.9 degrees (P = .02) and was still present 4 years after surgery.

CONCLUSIONS

Surgical conduction of ventricular reconstruction should be standardized to achieve the full spectrum of recoverable physiologic parameters. The renewal of ventricular torsion should be pursued as an adjunctive element of ventricular efficiency, mainly in ventricles that work at a critical level in the Frank-Starling relationship and pressure-volume loop.

Measuring myofiber orientations from high-frequency ultrasound images using multiscale decompositions

High-frequency ultrasound (HFU) has the ability to image both skeletal and cardiac muscles. The quantitative assessment of these myofiber orientations has a number of applications in both research and clinical examinations; however, difficulties arise due to the severe speckle noise contained in the HFU images. Thus, for the purpose of automatically measuring myofiber orientations from two-dimensional HFU images, we propose a two-step multiscale image decomposition method. It combines a nonlinear anisotropic diffusion filter and a coherence enhancing diffusion filter to extract myofibers. This method has been verified by ultrasound data from simulated phantoms, excised fiber phantoms, specimens of porcine hearts, and human skeletal muscles in vivo. The quantitative evaluations of both phantoms indicated that the myofiber measurements of our proposed method were more accurate than other methods. The myofiber orientations extracted from different layers of the porcine hearts matched the prediction of an established cardiac mode and demonstrated the feasibility of extracting cardiac myofiber orientations from HFU images ex vivo. Moreover, HFU also demonstrated the ability to measure myofiber orientations in vivo.

Off-pump epicardial ventricular reconstruction restores left ventricular twist and reverses remodeling in an ovine anteroapical aneurysm model

OBJECTIVE

The loss of normal apical rotation is associated with left ventricular (LV) remodeling and systolic dysfunction in patients with congestive heart failure after myocardial infarction. The objective of the present study was to evaluate the effect of epicardial ventricular reconstruction, an off-pump, less-invasive surgical reshaping technique, on myocardial strain, LV twist, and the potential alteration of myocardial fiber orientation in an ovine model of LV anteroapical aneurysm.

METHODS

LV anteroapical myocardial infarction was induced by coil embolization of the left anterior descending artery. Eight weeks after occlusion, epicardial ventricular reconstruction was performed using left thoracotomy under fluoroscopic guidance in 8 sheep to completely exclude the scar. The peak systolic longitudinal/circumferential strains and LV twist were evaluated using speckle tracking echocardiography before (baseline), after device implantation, and at 6 weeks of follow-up.

RESULTS

Epicardial ventricular reconstruction was completed in all sheep without any complications. Immediately after device implantation, LV twist significantly increased (4.18 ± 1.40 vs baseline 1.97 ± 1.92; P = .02). The ejection fraction had increased 17% and LV end-systolic volume had decreased 40%. The global longitudinal strain increased from -5.3% to -9.1% (P < .05). Circumferential strain increased in both middle and apical LV segments, with the greatest improvement in the inferior lateral wall (from -11.4% to -20.6%, P < .001). These effects were maintained ≥6 weeks after device implantation without redilation.

CONCLUSIONS

Less invasive than alternative therapies, epicardial ventricular reconstruction on the off-pump beating heart can restore LV twist and systolic strain and reverse LV remodeling in an ovine anteroapical aneurysm model.

Human atlas of the cardiac fiber architecture: study on a healthy population

Cardiac fibers, as well as their local arrangement in laminar sheets, have a complex spatial variation of their orientation that has an important role in mechanical and electrical cardiac functions. In this paper, a statistical atlas of this cardiac fiber architecture is built for the first time using human datasets. This atlas provides an average description of the human cardiac fiber architecture along with its variability within the population. In this study, the population is composed of ten healthy human hearts whose cardiac fiber architecture is imaged ex vivo with DT-MRI acquisitions. The atlas construction is based on a computational framework that minimizes user interactions and combines most recent advances in image analysis: graph cuts for segmentation, symmetric log-domain diffeomorphic demons for registration, and log-Euclidean metric for diffusion tensor processing and statistical analysis. Results show that the helix angle of the average fiber orientation is highly correlated to the transmural depth and ranges from -41° on the epicardium to +66° on the endocardium. Moreover, we find that the fiber orientation dispersion across the population (±13°) is lower than for the laminar sheets (±31°) . This study, based on human hearts, extends previous studies on other mammals with concurring conclusions and provides a description of the cardiac fiber architecture more specific to human and better suited for clinical applications. Indeed, this statistical atlas can help to improve the computational models used for radio-frequency ablation, cardiac resynchronization therapy, surgical ventricular restoration, or diagnosis and followups of heart diseases due to fiber architecture anomalies.

Resizable ventricular patch plasty in the porcine left ventricle: a pilot study

OBJECTIVE

: Endoventricular circular patch plasty is a method used to reconstruct the ventricular cavity in patients with (post) ischemic left ventricular aneurysm or global dilatation. However, late redilatation with mitral regurgitation has been reported, in which postoperative apex shape seems to play an important role. We studied the feasibility of ventricular volume downsizing with a variably shaped patch in porcine hearts.

METHODS

: In five in vitro and two acute animal experiments, a dyskinetic aneurysm was simulated with a pericardial insert. Reducing patch surface by changing patch shape diminished end-diastolic volume. In vitro, static end-diastolic volume was determined for each patch shape using volumetry and echocardiography. In the acute animal experiments, preliminary observations of patch behavior in live material were made, and pressure/time relationship, dPdTmax, was registered.

RESULTS

: In vitro, bringing the convex patch into a flat plane reduced LV volume from 66 ± 7 mL (aneurysm) to 49 ± 5 mL. Four of 5 patch shapes further reduced volume to a mean of 38 ± 7 mL (P = 0.03). The in vitro echocardiographic measurements correlated with volumetry findings (r = 0.81). In the acute animal experiments, dPdTmax varied with patch shape, independent of volume changes.

CONCLUSIONS

: In this pilot study, in vitro shape configuration of the resizable ventricular patch resulted in a calibrated end-diastolic volume reduction. The data of the two in vivo pilot experiments clearly indicate that change in patch configuration in the situation of more or less unchanged end-diastolic volume had impact on cardiac performance. Future studies must substantiate the results of this observation.