Structure function interface with sequential shortening of basal and apical components of the myocardial band

Helical structure of the ventricular myocardium. A narrative review of cardiac mechanics

To date, the ventricular myocardial band is the anatomical-functional model that best explains cardiac mechanics during systolic-diastolic phenomena in the cardiac cycle. The implications of the model fundamentally affect the anatomical interpretation of the ventricular myocardium, giving meaning to the direction that muscle fibers take, turning them into an object of study with potential clinical, imaging, and surgical applications. Re-interpreting the anatomy of the ventricular muscle justifies changes in the physiological interpretation, from its functional focus as a fiber unraveling the mechanical phenomena carried out during systole and diastole. We identify the functioning of the heart from the electrical and hemodynamic point of view, but it is necessary to delve into the mechanics that originate the hemodynamic changes observed flowmetrically, and that manifested during the pathology. In this review, the mechanical phenomena that the myocardium performs in each phase of the cardiac cycle are broken down in detail, emphasizing the physical displacements that each of the muscle segments presents, as well as a vision of their alteration and in which pathologies they are mainly identified. Visually, an anatomical correlation to the echocardiogram is provided, pointing out the direction of the segmental myocardial displacement by the strain velocity vector technique.

The Pacopexy procedure for left ventricular aneurysm: a 10-year clinical experience

PURPOSE

To evaluate our 10-year clinical experience of performing the Pacopexy procedure for left ventricular aneurysm (LVA).

METHODS

Between January, 1998 and November, 2015, a cohort of 92 patients with LVA underwent surgery to reshape the left ventricle. Fifty-seven patients underwent the Dor procedure and 35 underwent the Pacopexy procedure to emphasize the conical shape, whereby patch placement followed an oblique trajectory between the left ventricular apex and the septum below the aortic valve.

RESULTS

The early-mortality rate was 4.34% (4/92; n = 2 in each group). The 10-year survival rate was 70.4 ± 7.9% in the Pacopexy group vs 41.7 ± 7.2% in the Dor group (p < 0.05), and the rate of freedom from hospital re-admission for heart failure (HF) or cardiac death was 60.0 ± 8.6% vs 28.8 ± 6.8%, respectively (p < 0.05). The Dor procedure and left ventricular end systolic volume index (LVESVI) ≥ 60 ml/m² were strongly and significantly associated with long-term mortality and hospital re-admission for HF.

CONCLUSIONS

The Pacopexy procedure is a reproducible surgical option for the treatment of LVA. The improved configuration achieved by the Pacopexy procedure has resulted in good long-term survival and a high degree of freedom from re-admission for HF in patients with advanced LVA.

What Is the Heart? Anatomy, Function, Pathophysiology, and Misconceptions

Cardiac dynamics are traditionally linked to a left ventricle, right ventricle, and septum morphology, a topography that differs from the heart's five-century-old anatomic description of containing a helix and circumferential wrap architectural configuration. Torrent Guasp's helical ventricular myocardial band (HVMB) defines this anatomy and its structure, and explains why the heart's six dynamic actions of narrowing, shortening, lengthening, widening, twisting, and uncoiling happen. The described structural findings will raise questions about deductions guiding "accepted cardiac mechanics", and their functional aspects will challenge and overturn them. These suppositions include the LV, RV, and septum description, timing of mitral valve opening, isovolumic relaxation period, reasons for torsion/twisting, untwisting, reasons for longitudinal and circumferential strain, echocardiographic sub segmentation, resynchronization, RV function dynamics, diastolic dysfunction's cause, and unrecognized septum impairment. Torrent Guasp's revolutionary contributions may alter future understanding of the diagnosis and treatment of cardiac disease.

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.

Perioperative management of pulmonary hypertension in children with critical heart disease

OPINION STATEMENT

Pulmonary hypertension (PHTN) is common to a variety of conditions occurring in infants and children presenting to the intensive care unit. A fundamental understanding of the response of the right ventricle to an increase in afterload and the clinical syndromes responsible for PHTN is essential for managing patients with PHTN and critical heart disease. There are important distinguishing features between PHTN syndromes, and although one form of PHTN may predominate, often more than one mechanism of PHTN is contributing to the pathophysiologic state. Thus, it is imperative to tailor therapies accordingly in order to optimize outcomes.

Pathophysiology of right ventricular failure in pulmonary hypertension

This review focuses on right ventricular anatomy and function and the significance of ventricular interdependence in the response of the right ventricle to an increase in afterload. This is followed by a discussion of the pathophysiology of right ventricular failure in pulmonary arterial hypertension as well as in other clinical syndromes of pulmonary hypertension. Pulmonary hypertension is common in critically ill children and is associated with several conditions. Regardless of the etiology, an increase in right ventricular afterload leads to a number of compensatory changes in cardiovascular physiology. These changes are not altogether intuitive and require an understanding of right ventricular physiology and ventricular interdependence to optimize the care of these patients.

Surgical treatment for heart failure: left ventricular restoration for cardiomyopathy

Congestive heart failure has become a major problem and the only surgical treatment for end-stage heart failure caused by dilated cardiomyopathy (DCM) had been heart transplantation. However, because of the shortage of donors, several procedures for non-transplant surgery have been developed. Published literature on left ventricular (LV) restoration was searched to review the new surgical procedures for treating patients with ischemic or non-ischemic DCM. LV restoration was initiated in the 1980s for repairing LV aneurysm. In the 1990s several surgical procedures were introduced for treating DCM, and the new evolving surgical treatment plays an important role in the management of DCM in the 21st century.

Structure and function relationships of the helical ventricular myocardial band

OBJECTIVE

Understanding cardiac function requires knowledge of the architecture responsible for the normal actions of emptying and filling. Newer imaging methods are surveyed to characterize directional (narrowing, shortening, lengthening, and widening) and twisting motions.

METHODS

These movements are defined and then compared with a spectrum of models to introduce a useful "functional anatomy" that explains cardiac spatial and temporal relationships. The sequential nature of normal contraction differs from a synchronous beat.

RESULTS

The prior concept of constriction is replaced by understanding that clockwise and counterclockwise helical motions are necessary to cause the predominant twisting motion. The helical ventricular myocardial band model of Torrent-Guasp fulfills the architectural structure to define normal function. Expansion of information from this model allows novel understanding of mechanisms that explains why a component of ventricular suction involves a systolic event, clarifies septum function, determines diastolic dysfunction, introduces new treatments, shows how knowledge of the helical structure influences understanding of atrioventricular and biventricular pacing, and creates novel methods for introducing septal pacing stimuli.

CONCLUSION

Further testing of these spatial anatomic concepts is needed to create a more accurate understanding of the architectural mechanisms that underlie cardiac dynamics to address future problems in unhealthy hearts.

Potential implications of the helical heart in congenital heart defects

The anatomic and functional observations made by Francisco Torrent-Guasp, in particular his discovery of the helical ventricular myocardial band (HVMB), have challenged what has been taught to cardiologists and cardiac surgeons over centuries. A literature debate is ongoing, with interdependent articles and comments from supporters and critics. Adequate understanding of heart structure and function is obviously indispensable for the decision-making process in congenital heart defects. The HVMB described by Torrent-Guasp and the potential impact on the understanding and treatment of congenital heart defects has been analyzed in the following settings: embryology, ventriculo-arterial discordance (transposition of great arteries), Ebstein's anomaly, pulmonary valve regurgitation after repair of tetralogy of Fallot, Ross operation, and other congenital heart defects. The common structural spiral feature is only one of the elements responsible for the functional interaction of right and left ventricles, and understanding the form/function relationship in congenital heart defects is more difficult than for acquired heart disease because of the variety and complexity of congenital heart defects. Individuals involved in the care of patients with congenital heart defects have to be stimulated to consider further investigations and alternative surgical strategies.

Regional localisation of left ventricular sheet structure: integration with current models of cardiac fibre, sheet and band structure

The architecture of the heart remains controversial despite extensive effort and recent advances in imaging techniques. Several opposing and non-mutually compatible models have been proposed to explain cardiac structure, and these models, although limited, have advanced the study and understanding of heart structure, function and development. We describe key areas of similarity and difference, highlight areas of contention and point to the important limitations of these models. Recent research in animal models on the nature, geometry and interaction of cardiac sheet structure allows unification of some seemingly conflicting features of the structural models. Intriguingly, evidence points to significant inter-individual structural variability (within constrained limits) in the canine, leading to the concept of a continuum (or distribution) of cardiac structures. This variability in heart structure partly explains the ongoing debate on myocardial architecture. These developments are used to construct an integrated description of cardiac structure unifying features of fibre, sheet and band architecture that provides a basis for (i) explaining cardiac electromechanics, (ii) computational simulations of cardiac physiology and (iii) designing interventions.

Septal anterior ventricular exclusion operation (Pacopexy) for ischemic dilated cardiomyopathy: treat form not disease

Objective: Restoration of left ventricle size and shape is an effective surgical procedure in patients with dilated cardiomyopathy. This report defines early and intermediate results following the reshaping of the left ventricle from spherical to ellipsoid configuration in patients with ischemic cardiomyopathy, employing a technique for LV restoration (LVR) that uses form rather than disease as the endpoint for oblique patch placement. Methods: Between 1998 and 2004, a cohort of 83 patients with dilated ischemic cardiomyopathy underwent an operation to reshape the left ventricle. In 54 patients the Dor procedure was done, and 29 underwent the septal anterior ventricular exclusion (SAVE) procedure to emphasize the elliptical shape, whereby patch placement followed an oblique trajectory between the LV apex and septum below the aortic valve. Ventricular form, rather than the disease scar marked the suture placement site endpoint to create an ellipse. The mean age was 58 ± 27, but SAVE patients had larger end systolic volume index (135 ± 38 vs 95 ± 25*). Overall preoperative NYHA functional class III was in 69% and IV in 31 patients, but more SAVE patients were in class IV (38% vs 28%*). The procedures were elective in 72 and emergent in 11, with similar entry criteria for each procedure. Results: In combination with LVR operation, mitral surgery was performed in 49/83 and tricuspid annuloplasty in 23/83 patients, but these procedures were more common after SAVE (59% vs 44%* and 45% vs 19%*, respectively), because of larger LV volumes in SAVE patients; 2.8 ± 1.3 coronary artery bypass grafts were used. Perioperative use of IABP or LVAD was 15 and 1, respectively in 83 patients. Hospital death was in 1/11 or 9% after emergent operations and 3/72 or 4% in elective procedures, with no difference between groups. After discharge from the hospital, NYHA class improved to class I or II in 57 patients, class III/IV in 14 patients, with 10 late deaths. The 5-year survival rate after the elective operation was 80.3% in SAVE and with elective operation and 77.4% in the Dor procedure. Conclusion: The SAVE or Pacopexy technique is easy to reshape the dilated left ventricle from spherical to ellipsoid form after the LVR, and the resultant improved configuration may contribute to the overall results for patients with ischemic dilated cardiomyopathy.

Surgical management of right ventricular dysfunction late after repair of tetralogy of fallot: right ventricular remodeling surgery

With the increasing number of late survivors of repair of tetralogy of Fallot, surgical management of patients with right ventricular (RV) dysfunction and limited exercise capacity has become a more frequent problem. The wide variability in clinical status, extent of RV dilatation, and dysfunction at the time of presentation for surgical intervention has resulted in disparate surgical results after pulmonary valve insertion. With increasing use of magnetic resonance imaging, quantitative measures of RV volumes, function, and pulmonary regurgitant fraction have enabled a more systematic analysis of results. While there is a group of patients that responds favorably to pulmonary valve insertion, there is also a large subgroup that does not; this requires further analysis of the mechanisms responsible. We have developed a surgical approach to this latter group of patients, which incorporates the concepts of ventricular remodeling or restoration developed for the left ventricle following myocardial infarction. Preliminary results indicate that this procedure is equally safe to pulmonary valve insertion alone, and may result in improved RV function.