Rewind the heart: a novel technique to reset heart fibers' orientation in surgery for ischemic cardiomyopathy

Elucidating the mechanisms underlying left ventricular function recovery in patients with ischemic heart failure undergoing surgical remodeling: A 3-dimensional ultrasound analysis

OBJECTIVE

The study objective was to elucidate the mechanisms of left ventricle functional recovery in terms of endocardial contractility and synchronicity after surgical ventricular reconstruction.

METHODS

Real-time 3-dimensional transthoracic echocardiography was performed on 20 patients with anterior left ventricle remodeling and ischemic heart failure before surgical ventricular reconstruction and at 6-month follow-up, and on 15 healthy controls matched by age and body surface area. Real-time 3-dimensional transthoracic echocardiography datasets were analyzed through TomTec software (4D LV-Analysis; TomTec Imaging Systems GmbH, Unterschleissheim, Germany): Left ventricle volumes, ejection fraction, and global longitudinal strain were computed; the time-dependent endocardial surface yielded by 3-dimensional speckle-tracking echocardiography was postprocessed through in-house software to quantify local systolic minimum principal strain as a measure of fiber shortening and mechanical dispersion as a measure of fiber synchronicity.

RESULTS

Compared with controls, patients with heart failure before surgical ventricular reconstruction showed lower ejection fraction (P < .0001) and significantly impaired mechanical dispersion (P < .0001) and minimum principal strain (P < .0001); the latter worsened progressively from left ventricle base to apex. After surgical ventricular reconstruction, global longitudinal strain improved from -6.7% to -11.3% (P < .0001); mechanical dispersion decreased in every left ventricle region (P ≤ .017) and mostly in the basal region, where computed mechanical dispersion values were comparable to physiologic values (P ≥ .046); minimum principal strain improved mostly in the basal region, changing from -16.6% to -22.3% (P = .0027).

CONCLUSIONS

At 6-month follow-up, surgical ventricular reconstruction was associated with significant recovery in global left ventricle function, improved mechanical dispersion indicating a more synchronous left ventricle contraction, and improved left ventricle fiber shortening mostly in the basal region, suggesting the major role of the remote myocardium in enhancing left ventricle functional recovery.

Use of Multifactorial Treatments to Address the Challenge of Translating Experimental Myocardial Infarct Reduction Strategies

Myocardial tissue damage that occurs during an ischemic event leads to a spiraling deterioration of cardiac muscle structural and functional integrity. Reperfusion is the only known efficacious strategy and is the most commonly used treatment to reduce injury and prevent remodeling. However, timing is critical, and the procedure is not always feasible for a variety of reasons. The complex molecular basis for cardioprotection has been studied for decades but formulation of a viable therapeutic that can significantly attenuate myocardial injury remains elusive. In this review, we address barriers to the development of a fruitful approach that will substantially improve the prognosis of those suffering from this widespread and largely unmitigated disease. Furthermore, we proffer that ephrinA1, a candidate molecule that satisfies many of the important criteria discussed, possesses robust potential to overcome these hurdles and thus offers protection that surpasses the limitations currently observed.

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.

Role of left ventricular twist mechanics in cardiomyopathies, dance of the helices

Left ventricular twist is an essential part of left ventricular function. Nevertheless, knowledge is limited in “the cardiology community” as it comes to twist mechanics. Fortunately the development of speckle tracking echocardiography, allowing accurate, reproducible and rapid bedside assessment of left ventricular twist, has boosted the interest in this important mechanical aspect of left ventricular deformation. Although the fundamental physiological role of left ventricular twist is undisputable, the clinical relevance of assessment of left ventricular twist in cardiomyopathies still needs to be established. The fact remains; analysis of left ventricular twist mechanics has already provided substantial pathophysiological understanding on a comprehensive variety of cardiomyopathies. It has become clear that increased left ventricular twist in for example hypertrophic cardiomyopathy may be an early sign of subendocardial (microvascular) dysfunction. Furthermore, decreased left ventricular twist may be caused by left ventricular dilatation or an extensive myocardial scar. Finally, the detection of left ventricular rigid body rotation in noncompaction cardiomyopathy may provide an indispensible method to objectively confirm this difficult diagnosis. All this endorses the value of left ventricular twist in the field of cardiomyopathies and may further encourage the implementation of left ventricular twist parameters in the “diagnostic toolbox” for cardiomyopathies.

Ventricular structure-function relations in health and disease: part II. Clinical considerations

Normal cardiac function of the left and right ventricles, together with the septum, is related to form/function interactions within the helical ventricular myocardial band. This knowledge is a prerequisite to understanding form/function interactions in diseases and for planning new treatments. Topics discussed include congestive heart failure in dilated hearts of ischaemic, valvar or nonischaemic origin as well as diastolic dysfunction. Similar thinking underlies novel treatments for dyssynchrony in pacing, together with focusing upon varying global left or right ventricular anatomy to correct mitral and tricuspid insufficiency caused by tethering of the leaflets. The septum is the lion of the right ventricle and insight is provided into offsetting septal damage during cardiac surgery, rebuilding its anatomical structure in post-tetralogy pulmonary insufficiency, as well as rectifying its dysfunction by decompression in patients with a left ventricular assist device.

Surgical ventricular restoration for the treatment of heart failure

Heart failure (HF) is an emerging epidemic affecting 15 million people in the USA and Europe. HF-related mortality was unchanged between 1995 and 2009, despite a decrease in the incidence of cardiovascular disease. Conventional explanations include an aging population and improved treatment of acute myocardial infarction and HF. An adverse relationship between structure and function is the central theme in patients with systolic dysfunction. The normal elliptical ventricular shape becomes spherical in ischemic, valvular, and nonischemic dilated cardiomyopathy. Therapeutic decisions should be made on the basis of ventricular volume rather than ejection fraction. When left ventricular end-systolic volume index exceeds 60 ml/m², medical therapy, CABG surgery, and mitral repair have limited benefit. This form-function relationship can be corrected by surgical ventricular restoration (SVR), which returns the ventricle to a normal volume and shape. Consistent early and late benefits in the treatment of ischemic dilated cardiomyopathy with SVR have been reported in >5,000 patients from various international centers. The prospective, randomized STICH trial did not confirm these findings and the reasons for this discrepancy are examined in detail. Future surgical options for SVR in nonischemic and valvular dilated cardiomyopathy, and its integration with left ventricular assist devices and cell therapy, are described.

'Let's twist again': surgically induced renewal of left ventricular torsion in ischemic cardiomyopathy

OBJECTIVES

To test the potential of the heart to be surgically restored at a near-normal global condition, granted that its physiological characteristics are respected (working volumes, chamber geometry, fiber orientation, opposite rotation of apex and base, global torsion and strain).

METHODS

From May 2007 to December 2008, 12 consecutive patients with ischemic cardiomyopathy were included in this study. All patients underwent modified surgical anterior ventricular restoration combined with complete coronary revascularization and, when indicated, mitral anuloplasty. The modified restoration aims to re-approach residual myocardium, redirecting fiber orientation displaced by infarct scar toward a more physiological gross disposition. Patients were studied preoperatively and postoperatively with a complete echocardiographical assessment, including speckle-tracking analysis.

RESULTS

Standard parameters significantly improved after the operation (end diastolic volume, P < 0.001; end systolic volume, P < 0.001; ejection fraction, P = 0.004), and so did peak systolic apical rotation, peak systolic left ventricular torsion and two-chamber and four-chamber longitudinal strain (P = 0.004, 0.003, 0.05 and 0.01, respectively). Pearson's correlation between apical rotation and longitudinal strain (two-chamber and four-chamber) was -0.877 (P < 0.001) and -0.720 (P = 0.008), respectively, and between torsion and longitudinal strain was -0.845 (P = 0.001) and -0.785 (P = 0.002), respectively.

CONCLUSION

This study reveals an unexpected potential of the myocardium to be restored at a near-normal global condition, with regard to all of its physiological characteristics. The concept of fiber-based surgical treatment, supported by an imaging-guided preoperative study, could widen the potential of repairing a failing heart.

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

BACKGROUND

The history of surgical reconstruction of the left ventricle after an anterior myocardial infarction shows an evolution of techniques which tend to a more and more physiologic restoration of ventricular shape and volume, with increasing attention to the orientation of myocardial fibers.

METHODS

We set a new surgical procedure for endoventricular patch reconstruction technique with the aim to rebuild a physiologic shape and volume of the left ventricle caring about realignment of myocardial fibers orientation. Peculiarities of this reconstruction are the shape of the patch (reduction of minor axis compared with currently used oval-shaped patch) and the asymmetrical way of suturing it inside the ventricle.

RESULTS

We present a detailed description of operative steps of this procedure, and we add some relevant surgical hints to clarify its peculiarities. Most of the patients operated on with this technique showed the original renewal of apical rotation and left ventricular torsion as specific index of the restoration of physiologic fiber orientation: we report an exemplary case of at-sight recovery of apical rotation in the operating room.

CONCLUSION

This technique can represent a reproducible new way to realign myocardial fibers in a near-normal setting, improving the physiological restoration of ischemically injured left ventricle. It could be also the basis to reconsider surgical treatment for heart failure.