Spatial orientation of the ventricular muscle band: physiologic contribution and surgical implications

Barium-enhanced imaging of the coronary vasculature of the porcine myocardium: empirical investigation into the theory of the ventricular myocardial band

OBJECTIVE

The ventricular myocardium is thought to exist as a single continuous muscle band that extends from the pulmonary artery to the aorta, wrapped into a double helical coil Torrent-Guasp's theory of the ventricular myocardial band (VMB). The purpose of this study was to examine the coronary blood supply to the VMB and to evaluate the effect of coronary blood systems on structure-function relations in the myocardium.

METHODS

VMBs of nine swine hearts were unwrapped after postmortem barium coronary angiography. Unwrapped VMBs underwent radiography, and vascular images of barium remaining in the VMBs were evaluated.

RESULTS

We were able to achieve a single longitudinal and stretched myocardial band in all nine porcine hearts. The corresponding regions supplied by each coronary artery were clearly distinguishable in the VMBs. The right segment of the basal loop was supplied by the right coronary artery. The left segment of the basal loop was supplied by the left circumflex artery. Most of the descending segment of the apical loop was supplied by the left anterior descending artery, with an inferior portion supplied by the right coronary artery. Most of the ascending segment of the apical loop was supplied by the left anterior descending artery, with a posterior portion supplied by the left circumflex artery.

CONCLUSION

Understanding the trinity of structure, function, and coronary blood supply from the viewpoint of the VMB should facilitate development of more effective surgical treatment for severe ischemic heart disease.

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

Ischemic cardiomyopathy is the most common cause of dilated cardiomyopathy and congestive heart failure. It affects approximately 1 out of 100 people, most often middle-aged to elderly men. Left ventricular restoration surgery is a challenging therapeutic approach to this pathology: it aims to rebuild a near-normal ventricular chamber in a heart damaged by a myocardial infarction, reducing its volume and improving the fraction of blood ejected by each systole. This is obtained by eliminating the akinetic/dyskinetic part of the cardiac muscle and closing the final defect with or without a synthetic patch. Optimization of surgical repair is mandatory as far as ischemic cardiomyopathy is a worldwide disease responsible for many cardiac deaths and because of its potential use as an alternative to heart transplantation in selected patients. Until now, this surgery has been performed without caring for myocardial fibers' disposition but recent evidences clarified the key role of fibers' alignment in heart physiology. The myocardium of the left ventricle has a unique three-dimensional, multilayered structure: it constitutes the anatomical basis for the cardiac function and for left ventricular torsion, a key movement of normal heart. Myocardial infarction alters myocardial structure in the site of the necrosis and subsequent cardiomyopathy eliminates left ventricular torsion. On the other hand, histological evidences show that myofibers' orientation in the thickness of residual normal myocardium is not changed and that transmural courses of fiber orientation angles near infarct zones were similar to those of normal myocardium. We hypothesize that, with a particular surgical technique, it could be possible to realign the anatomically normal fibers of the residual myocardium in order to rebuild a physiologic setting. We planned a novel surgical technique of left ventricular restoration using a very narrow, string-shaped patch and a particular suturing sequence and technique, whose aim is to near normally oriented residual myocardial fibers. The renewal of left ventricular torsion was evident at sight just at the end of this kind of ventricular restoration, still in the operating room, then confirmed by 2D speckle tracking echocardiography. These observations are indirect proofs of fibers' realignment, as the torsion movement of the left ventricle is due to the interlaced, oblique orientation of myocardial fibers. We herein propose a theoretical explanation of this outcome, drawing a geometrical modeling of the surgical procedure.

Augmentation of left ventricular torsion with exercise is attenuated with age

BACKGROUND

Left ventricular torsion, resulting from the rotation of the base and apex of the ventricle in opposite directions, may be an important component of normal cardiac function both at rest and with exercise. The effect of exercise on torsion in the general population and the influence of aging on changes in torsion with exercise are not known.

METHODS

Analysis of torsion, positive and negative torsion velocities, and negative torsion acceleration was performed using speckle tracking imaging on 33 stress echocardiograms using supine bicycle stress.

RESULTS

Resting and postexercise torsion could be assessed in 14 patients (42%). A total of 19 patients who were significantly older and larger (mean age 57 years, mean body mass index 28.2, both P < .03) were excluded as a result of inadequate frame rate and image quality after exercise. After exercise, significant increases in peak torsion (10.3 +/- 0.8 vs 13.3 +/- 1.3 degrees, P < .04), peak positive torsion (54.2 +/- 5.6 vs 113.6 +/- 12.3 degrees/s, P < .0001), and peak negative torsion (-56.3 +/- 7.9 vs -100.8 +/- 14.8 degrees/s, P < .03) velocities were observed. Ejection fraction correlated with torsion both at rest and after exercise (r = 0.63, P < .0004). At rest, torsion was greater in older individuals (8.9 +/- 0.6 vs 11.6 +/- 1.2 degrees, P < .04). With increasing age, exercise resulted in less augmentation of torsion (r = 0.59, P < .02) and positive torsion velocity (r = -0.79, P < .003), and decreased negative torsional acceleration (r = 0.60, P < .035).

CONCLUSIONS

Exercise results in increased cardiac plecotropy (the augmentation of torsion parameters in response to load or stimulus) but this effect is attenuated with aging. Further investigation is required to determine whether impairment of plecotropy contributes to the reduced exercise capacity associated with aging.

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.

Construction of the global lagrangian strain field in the myocardium using DENSE MRI data

The main aim of this study is to generate global strain maps within the myocardial wall. Transmural strain calculations are performed using DENSE MRI data, acquired in a long-axis plane for canine subjects over the complete cardiac cycle. Continuum mechanics formulations were applied to all segments of the myocardium and later analyzed from anatomical and physiological perspectives. Characteristic parameters of the myocardial wall - namely global strain distributions - were quantified by means of numerical analyses of DENSE MR data. Our study demonstrated the initiation of myocardial strain as well as heterogeneous contraction patterns across the ventricle wall. There were measurable wall shear strains throughout the cardiac cycle, with the maximum strain within the long-axis plane concentrated in the septal wall at the start of systole and later becoming more pronounced in the lateral wall in the diastolic period. The methods described will lead to a better understanding of the complex myocardial contraction from these space- and time-resolved data on wall motion.

Surgery of left ventricular aneurysm: a meta-analysis of early outcomes following different reconstruction techniques

BACKGROUND

The purpose of this study is to assess the effects of linear and geometric left ventricular aneurysm reconstruction on early postoperative outcomes.

METHODS

A search of computerized databases supplemented with manual bibliographic review was performed for all peer-reviewed English language publications concerning randomized and nonrandomized studies reporting the results of left ventricular reconstruction after both linear and geometric reconstruction techniques. Meta-analyses of several short-term outcomes were performed.

RESULTS

No randomized trial was identified. Eighteen nonrandomized trials were found with a total of 1,814 and 803 patients who underwent linear and geometric reconstruction, respectively. Meta-analysis of all studies (n = 18) revealed an increased risk of in-hospital death for patients undergoing linear reconstruction (relative risk = 1.59, 95% confidence interval: 1.12 to 2.26, p = 0.01). The subanalysis of studies in which linear reconstruction was adopted mainly in the first period of time, and geometric reconstruction was adopted in a later phase, still showed a significant advantage in terms of in-hospital mortality for patients undergoing geometric reconstruction (n = 11 studies, relative risk = 1.89, 95% confidence interval: 1.22 to 2.93, p = 0.004). By contrast, when the two surgical approaches were carried out in the same time lag, there was no difference between linear and geometric reconstruction techniques (n = 7 studies, relative risk = 1.04, 95% confidence interval: 0.57 to 1.92, p = 0.89). No differences in the other outcomes of interest were observed.

CONCLUSIONS

The advantage for geometric reconstruction techniques in terms of in-hospital mortality shown in some studies can be an effect of learning curve or of improvement over time in management of these difficult patients. Further studies are required to clarify this issue.

Left ventricular form and function revisited: applied translational science to cardiovascular ultrasound imaging

Doppler tissue imaging (DTI) and DTI-derived strain imaging are robust physiologic tools used for the noninvasive assessment of regional myocardial function. As a result of high temporal and spatial resolution, regional function can be assessed for each phase of the cardiac cycle and within the transmural layers of the myocardial wall. Newer techniques that measure myocardial motion by speckle tracking in gray-scale images have overcome the angle dependence of DTI strain, allowing for measurement of 2-dimensional strain and cardiac rotation. DTI, DTI strain, and speckle tracking may provide unique information that deciphers the deformation sequence of complexly oriented myofibers in the left ventricular wall. The data are, however, limited. This review examines the structure and function of the left ventricle relative to the potential clinical application of DTI and speckle tracking in assessing the global mechanical sequence of the left ventricle in vivo.

Intramyocardial Pacing and Sensing for the Enhancement of Cardiac Stimulation and Sensing Specificity

BACKGROUND

Intracardiac electrodes create an "antenna" capable of unintentionally recording and stimulating tissue beyond the chamber in which they are positioned, resulting in far-field R wave oversensing in pacemakers and inappropriate detection in defibrillators. This feasibility study sought to determine whether a specially constructed lead with two distal totally intramyocardial electrodes could overcome these limitations.

METHODS

Two mongrel dogs were anesthetized and a median sternotomy performed. Epicardial intramyocardial pacing and sensing function was assessed and compared to standard active fixation pacing and sensing placed at the same atrial and ventricular sites. Right ventricular pacing was also assessed.

RESULTS

For the novel intramyocardial lead, the average R wave amplitude was 7.2 mV, compared to an average R wave of 8.4 mV for the standard active fixation lead placed at identical ventricular sites; P-waves were also similar. Cross-chamber sensing was present in the ventricle and atrium with the standard lead, and absent with the intramyocardial lead. The average pacing threshold was 0.7 mA at 0.2 ms for the novel lead compared to 1.1 mA for the standard lead. With the standard lead, phrenic stimulation was seen at threshold (cathode distal) and at 3 mA (cathode proximal electrode). No phrenic stimulation was seen with the novel intramyocardial lead despite outputs up to 20 mA at sites located 3-5 mm from the phrenic nerve.

CONCLUSION

Totally intramyocardial pacing is feasible, and results in site-specific pacing and sensing function. This may eliminate far-field signal oversensing and phrenic stimulation in future devices.

Atrioventricular plane displacement is the major contributor to left ventricular pumping in healthy adults, athletes, and patients with dilated cardiomyopathy

Previous studies using echocardiography in healthy subjects have reported conflicting data regarding the percentage of the stroke volume (SV) of the left ventricle (LV) resulting from longitudinal and radial function, respectively. Therefore, the aim was to quantify the percentage of SV explained by longitudinal atrioventricular plane displacement (AVPD) in controls, athletes, and patients with decreased LV function due to dilated cardiomyopathy (DCM). Twelve healthy subjects, 12 elite triathletes, and 12 patients with DCM and ejection fraction below 30% were examined by cine magnetic resonance imaging. AVPD and SV were measured in long- and short-axis images, respectively. The percentage of the SV explained by longitudinal function (SVAVPD%) was calculated as the mean epicardial area of the largest short-axis slices in end diastole multiplied by the AVPD and divided by the SV. SV was higher in athletes [140 ± 4 ml (mean ± SE), P = 0.009] and lower in patients (72 ± 7 ml, P < 0.001) when compared with controls (116 ± 6 ml). AVPD was similar in athletes (17 ± 1 mm, P = 0.45) and lower in patients (7 ± 1 mm, P < 0.001) when compared with controls (16 ± 0 mm). SVAVPD%was similar both in athletes (57 ± 2%, P = 0.51) and in patients (67 ± 4%, P = 0.24) when compared with controls (60 ± 2%). In conclusion, longitudinal AVPD is the primary contributor to LV pumping and accounts for ∼60% of the SV. Although AVPD is less than half in patients with DCM when compared with controls and athletes, the contribution of AVPD to LV function is maintained, which can be explained by the larger short-axis area in DCM.

The helical ventricular myocardial band of Torrent-Guasp

We live in an era of substantial progress in understanding myocardial structure and function at genetic, molecular, and microscopic levels. Yet, ventricular myocardium has proven remarkably resistant to macroscopic analyses of functional anatomy. Pronounced and practically indefinite global and local structural anisotropy of its fibers and other ventricular wall constituents produces electrical and mechanical properties that are nonlinear, anisotropic, time varying, and spatially inhomogeneous. The helical ventricular myocardial band of Torrent-Guasp is a revolutionary new concept in understanding global, 3-dimensional, functional architecture of the ventricular myocardium. This concept defines the principal, cumulative vectors, integrating the tissue architecture (ie, form) and net forces developed (ie, function) within the ventricular mass. The primary purpose of this review is to emphasize the importance of this concept, in the light of collaborative efforts to establish an integrative approach, defining ventricular form and function by linking across multiple scales of biological organization, as explained in the ongoing Physiome project. Because one of the most important scientific missions in this century is integration of basic research with clinical medicine, we believe that this knowledge is not of merely academic importance, but is also the essential prerequisite in clinical evaluation and treatment of different heart diseases.

Left ventricular structure and function: basic science for cardiac imaging

The myofiber geometry of the left ventricle (LV) changes gradually from a right-handed helix in the subendocardium to a left-handed helix in the subepicardium. In this review, we associate the LV myofiber architecture with emerging concepts of the electromechanical sequence in a beating heart. We discuss: 1) the morphogenesis and anatomical arrangement of muscle fibers in the adult LV; 2) the sequence of depolarization and repolarization; 3) the physiological inhomogeneity of transmural myocardial mechanics and the apex-to-base sequence of longitudinal and circumferential deformation; 4) the sequence of LV rotation; and 5) the link between LV deformation and the intracavitary flow direction observed during each phase of the cardiac cycle. Integrating the LV structure with electrical activation and motion sequences observed in vivo provides an understanding about the spatiotemporal sequence of regional myocardial performance that is essential for noninvasive cardiac imaging.

Impaired systolic torsion in dilated cardiomyopathy: reversal of apical rotation at mid-systole characterized with magnetic resonance tagging method

Left ventricular (LV) torsion plays an important role in squeezing the blood out of the heart. To characterize the systolic torsion in LV dysfunction, we studied using magnetic resonance imaging myocardial tagging method in 26 subjects: 17 patients with dilated cardiomyopathy (DCM, LV ejection fraction [EF], 27 +/- 8%) and 9 healthy control subjects. Grid-tagged LV short-axis cine images were acquired at base, mid and apex levels. Tag-intersections were tracked during the systole, thereby determining rotation angle (positive indicated clockwise from the apex). Peak torsion was defined as the maximum difference in rotation angle between the base and apex. Time to peak torsion was expressed as % systole by dividing the time by a total systolic time. Amplitude of the rotation at peak was less in DCM than in controls at both the base (0.1 +/- 2.9 vs. 2.6 +/- 1.6 degrees , P < 0.05) and apex (-5.9 +/- 5.3 vs. -11.2 +/- 2.5 degrees , P < 0.01). Amplitude of peak torsion was then less in DCM than in controls (6.1 +/- 3.4 vs. 13.6 +/- 2.5 degrees , P < 0.001), and the timing of peak was earlier (66 +/- 22 vs. 104 +/- 16% systole, P < 0.001). The amplitude of peak torsion was correlated with LVEF (r=0.74, P < 0.001). In conclusion, amplitude of systolic torsion was impaired in proportion to LV function. Systolic torsion in LV dysfunction was characterized by the discontinuing counter-rotation of the apex to the base before end-systole.

A more comprehensive left ventricular repair for severely dilated cardiomyopathy

We report a patient with cardiogenic shock due to severely dilated cardiomyopathy who underwent complex, but comprehensive left ventricle (LV) repair. Preoperative investigation showed marked LV dilatation, poor LV function, severe mitral and tricuspid regurgitation, and total occlusion of two coronary arteries. We urgently performed (1) modified Batista operation which preserves the LV apex, (2) septal anterior ventricular exclusion (SAVE) operation, (3) mitral annuloplasty, (4) tricuspid annuloplasty, and (5) coronary bypass. Postoperative evaluation revealed good graft flow, reduced LV dimension preserving the elliptical shape, improved LV function, and minimal MR. Twenty-six months postoperatively, the patient has minimum clinical symptoms (NYHA: I).

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.

Longitudinal but not circumferential deformation reflects global contractile function in the right ventricle with open pericardium

The clinical evaluation of right ventricular (RV) contractility is problematic because instantaneous RV volumetry is difficult to achieve. Our aim was to test whether global RV contractility can be assessed by using regional indexes in the longitudinal and/or circumferential axis. Six anesthetized adult ewes were instrumented with a RV conductance catheter and four RV free wall sonomicrometry crystals (interrogating the longitudinal and circumferential axes). Global and regional preload recruitable stroke work (PRSW) were measured by using acute vena cava occlusions at baseline, during esmolol and dobutamine infusion, and during stable low-preload and high-afterload conditions. The agreement between regional and global PRSW was assessed with regression and Bland-Altman analysis. Both regional PRSW indexes correlated well with global PRSW in baseline conditions, during inotropic modulation (R(2) = 0.83 and 0.74 for longitudinal and circumferential regional PRSW, respectively), and during preload reduction (R(2) = 0.62 and 0.83, respectively), but only longitudinal regional PRSW correlated with global PRSW in increased afterload conditions (R(2) = 0.59 and 0.13 for longitudinal and circumferential regional PRSW, respectively). We conclude that in the open-chest, open-pericardium animal model, deformation in the longitudinal axis accurately reflects global RV contractile function in baseline conditions and during acute load modulation, whereas circumferential motion is influenced by changes in afterload.

A surgical approach to severe congestive heart failure--overlapping ventriculoplasty

BACKGROUND

Previously we developed a new procedure of overlapping cardiac volume reduction (OLCVR) surgery for patients with dilated cardiomyopathy refractory to medical treatment. Papillary muscle plication (PMP) when combined with OLCVR may achieve a better clinical outcome.

PURPOSE

To investigate the early and intermediate results of OLCVR with or without PMP.

METHODS

Twenty-five patients (21 males, 4 females, aged 60 +/- 13 years) with either ischemic (n = 7) or nonischemic (n = 18) dilated cardiomyopathy underwent either isolated OLCVR (n = 11; Original Group) or PMP combined with OLCVR (n = 14; Integrated Group).

RESULTS

Early deaths occurred in two (8%) from a noncardiac cause and late deaths in six, two from a cardiac and four from a noncardiac cause. Postoperative data in survivors were significantly improved in terms of NYHA functional class (from 3.6 +/- 1.9 to 1.6 +/- 1.1), ejection fraction (from 18 +/- 6% to 31 +/- 8%), left ventricular diastolic dimension (from 73 +/- 9 to 65 +/- 6 mm), and left ventricular end-diastolic volume index (from 194 +/- 81 to 128 +/- 43 mL/m2) (p < 0.05) in selected comparative cases. One-year crude and cause-specific survivals were 70.9% and 83.1%, respectively, at a mean follow-up of 12.8 months. One-year crude survival of the Integrated and Original Group was 85.7% and 55.6%, respectively (p = 0.24).

CONCLUSIONS

Although limitations exist in evaluating operative results, we consider OLCVR to be a relatively safe and effective procedure for selected patients with dilated cardiomyopathy. The addition of PMP to OLCVR may enhance the elliptic formation of left ventricle shape and improve mitral valve tethering, but further study is mandatory.

Ventricular Structure and Surgical History

The Reviews report will establish guidelines that underlie why the "restoration concept" may develop a paradigm shift in thinking, by addressing the geometric underpinnings of heart failure and their evolution. This presentation will (a) show that the underlying structure of the failing dilated heart involves a cardiac architectural change from the normal elliptical shape toward a dilated spherical form, (b) define the anatomic framework of this shape change, (c) convey the functional characteristics of heart function that result from this architectural underpinning, (d) describe the pattern of CHF development, (e) indicate imaging measurement guidelines to follow as heart form adversely changes from ellipse to sphere, (f) identify how such architectural changes alter prognosis, and (g) develop a historical evolution of surgical approaches to alter form to improve function to create the background for subsequent RESTORE team reports of current restoration to treat CHF and its complications.

Septal reshaping

Left ventricular (LV) aneurysm is a complication of an acute myocardial infarction (AMI). Herein a new technique is described that is indicated when the postinfarctual scar involves the septum more than the free wall. The incision starts at the apex and is directed, parallel to LAD, toward the base of the heart. The septum is rebuilt using 1 or 2 U-stitches, passed from inside, to join the anterior wall to the septum. The starting point begins as high as the scar, maintaining an oblique direction toward the new apex. An oval dacron patch is then sutured from the septum (end of the direct suture through the border with the inferior septum) to the anterior wall (between the healthy and the scarred wall) up to the new apex. Thirty-day mortality is low. This procedure provides good midterm results. New York Heart Association class improved from 2.7±0.9 to 1.6±0.5 (P≪0.001). Left ventricle (end-diastolic and end-systolic) volume, reduced significantly. Stroke volume normalized and ejection fraction increased even if not significantly. Mitral regurgitation reduced significantly from 2.5 to 0.6. No new mitral regurgitation developed.

Midterm results after septal reshaping for anteroseptal scars

BACKGROUND

Midterm clinical and morphologic results of the septal-reshaping exclusion of anteroseptal dyskinetic or akinetic areas were evaluated.

METHODS

From January to June 2003, 44 patients with myocardial infarction following left anterior descending coronary artery (LAD) occlusion underwent septal reshaping. The mean (+/- SD) New York Heart Association (NYHA) class of the patients at admission was 2.7 +/- 0.9. Angina was referred in 21 cases. The incision was started at the apex and directed parallel to the LAD toward the base of the heart. The septum was rebuilt with 1 or 2 U-stitches passed from the inside to join the anterior wall to the septum by starting as high as possible where the scar began and continuing in an oblique direction toward the new apex. An oval polyethylene terephthalate fiber (Dacron) patch was then sutured from the septum (at the end of the direct suture through the border with the inferior septum) to the anterior wall (between the healthy wall and the scarred wall) and up to the new apex.

RESULTS

The 30-day mortality rate was 2.2% (1 patient, due to the failure of a previously implanted defibrillator). Three patients experienced acute renal failure. No patient had restrictive syndrome. After a mean follow-up period of 8.5 +/- 4.9 months (range, 4-22 months), the mean NYHA class improved from 2.7 +/- 0.9 to 1.6 +/- 0.5 (P < .001). The 18- month survival rate and the probability of being alive in NYHA class I or II were 93.2% +/- 2.0% and 90.9% +/- 4.3%, respectively. Echocardiographic results showed reductions in the left ventricle volume with a normalization of the stroke volume. The diastolic longitudinal length remained unchanged, and the diastolic sphericity index was reduced but not significantly.

CONCLUSIONS

At 1 year after surgery, the good clinical and morphologic results demonstrate the safety and effectiveness of septal reshaping for anteroseptal scars.

Septal reshaping for exclusion of anteroseptal dyskinetic or akinetic areas

BACKGROUND

Our purpose is to describe a technique for exclusion of anteroseptal dyskinetic or akinetic areas.

METHODS

From January to December 2002, 22 consecutive patients with myocardial infarction following left anterior descending artery occlusion underwent septal reshaping. All of them were admitted for dyspnea. Eight patients were referred for angina. After a 5 to 8 cm apical incision, 2 U stitches were passed from inside to join the anterior wall to the septum, as high as possible, following the border of the scars. An oval Dacron patch was then sutured from the septum (end of the direct suture through the border with the inferior septum) to the anterior wall (between the healthy and the scarred wall) up to the new apex. Purpose of the procedure is to maintain a longitudinal size as similar as possible to the normal. The incision was closed in a double layer.

RESULTS

No patient died and only one had acute renal failure. No patients had restrictive syndrome. After a mean follow-up of 6.7 +/- 3.6 months (3 to 15), mean New York Heart Association Class improved from 2.7 +/- 1.1 to 1.2 +/- 0.3 (p < 0.001). Echocardiographic results showed reduction of left ventricle volumes and normalization of the stroke volume. In patients with low ejection fraction (<or=35%), left ventricular volumes decreased with a concomitant ejection fraction increase and a normal stroke volume. In patients with smaller cavities, significant reduction of left ventricular cavities was also obtained, with similar changes in ejection fraction and normal stroke volume.

CONCLUSIONS

This technique treats all the dyskinetic or akinetic areas following left anterior descending artery occlusion, when the septal involvement is higher than the anterior free wall. Clinical and morphologic results are good.

Nontransplant surgical options for congestive heart failure

Although advanced heart failure has been considered the main indication for heart transplantation, the increasing number of candidates and shortage of organs for transplantation, with accumulating waiting lists, has originated another look into more conventional surgery, previously considered of prohibitive risk. In fact, many cases are a result of anatomic lesions that can be corrected by conventional surgery, and in the past decade many surgical groups have obtained good and even excellent results in the treatment of aortic stenosis with low output, and in aortic and mitral regurgitation with severe left ventricular (LV) dysfunction. Also, ischemic and idiopathic dilated cardiomyopathy have been successfully treated by several types of LV remodeling surgery, with or without coronary grafting. Many of these procedures achieved excellent operative, medium-, and long-term results and survival, which match well those observed with cardiac transplantation, most often with advantages in the quality of life and, not unimportantly, in financial costs. For operated patients, especially those with ischemic cardiomyopathy, close follow-up for cardiac failure is extremely important in order to detect the right moment for heart transplantation, if it becomes necessary.

Importance of preserving the apex and plication of the base in left ventricular volume reduction surgery

OBJECTIVE

Volume reduction surgery for dilated cardiomyopathy has not yielded predictable outcomes. The purpose of this study was to clarify the efficacy of modified volume reduction surgery in preserving the left ventricular apex and reducing the left ventricular diameter at the base to maintain fiber continuity.

METHODS

Heart failure was induced with propranolol in 12 dogs, and the animals were randomized into 2 groups. In one group the left ventricular wall was plicated between the 2 papillary muscles from the middle to the apex (apex-sacrificing volume reduction surgery, group A, n = 6), and in the other group plication was done from the base to the middle (apex-sparing volume reduction surgery, group B, n = 6). Left ventricular function was then compared between the groups by using echocardiography and sonomicrometry crystals.

RESULTS

After volume reduction surgery, the fractional area change at the base in group B was greater than that in group A (40% +/- 3% vs 27% +/- 4%, P =.003). Cardiac output in group B was better than that in group A (2.5 +/- 0.2 vs 1.8 +/- 0.2 L/min, P =.023). Left ventricular end-diastolic pressure in group A was higher than that in group B (16 +/- 2 vs 8 +/- 1 mm Hg, P =.001). Fractional shortening in the long axis, as assessed by means of sonomicrometry, was better in group B than in group A.

CONCLUSIONS

Apex-sparing volume reduction surgery capable of maintaining left ventricular fiber continuity provided better left ventricular function in both the systolic and diastolic phases than apex-sacrificing volume reduction surgery in the acute heart failure model. This modification might improve the results of left ventricular volume reduction surgery.

Alterations in left ventricular torsion in tachycardia-induced dilated cardiomyopathy

OBJECTIVE

Left ventricular torsion reduces transmural systolic gradients of fiber strain, and torsional recoil in early diastole is thought to enhance left ventricular filling. Left ventricular remodeling in dilated cardiomyopathy may result in changes in torsion dynamics, but these effects are not yet characterized. Tachycardia-induced cardiomyopathy is accompanied by systolic and diastolic heart failure and left ventricular remodeling. We hypothesized that cardiomyopathy would alter systolic and diastolic left ventricular torsion mechanics, and this hypothesis was tested by studying sheep before and after the development of tachycardia-induced cardiomyopathy.

METHODS

Implanted miniature radiopaque markers were used in 8 sheep to measure left ventricular geometry and function, maximal torsional deformation, and early diastolic recoil before and after rapid ventricular pacing was used to create tachycardia-induced cardiomyopathy.

RESULTS

All animals had significant heart failure with ventricular dilatation and remodeling. With tachycardia-induced cardiomyopathy, maximum torsion relative to control conditions decreased (1.69 degrees +/- 0.61 degrees vs 4.25 degrees +/- 2.33 degrees ), and early diastolic recoil was completely abolished (0.53 degrees +/- 1.19 degrees vs -1.17 degrees +/- 0.94 degrees ).

CONCLUSIONS

Cardiomyopathy is accompanied by decreased and delayed systolic left ventricular torsional deformation and loss of early diastolic recoil, which may contribute to left ventricular dysfunction by increasing systolic transmural strain gradients and impairing diastolic filling. Analysis of left ventricular torsion with radiofrequency-tagging magnetic resonance imaging should be explored to elucidate the role of torsion in patients with cardiomyopathy.

Optimizing ventricular shape in anterior restoration

Ishemic dilated cardiomyopathy results from altered muscle mechanics. Ventricular restoration is aimed at altering the volume and shape changes that follow myocardial infarction. Optimal surgical methods to achieve this goal are not well defined, but it has been shown that sphericity is an important determinant of long-term outcome. We present the rationale and techniques for returning the globular remodeled ventricle to a more elliptical shape. Clinical data from our RESTORE registry does not suggest an improvement in early or late mortality with such methods but opens the way for late evaluation of functional and exercise capacity.

The structure and function of the helical heart and its buttress wrapping. V. Anatomic and physiologic considerations in the healthy and failing heart

A macroscopic structure of an elliptic heart, formed by the helix provided by the apical loop, is defined and related, initially, to normal function. To define the sequence of normal progressive muscular activity, cardiac pressure, magnetic resonance imaging (MRI), and multiple gated acquisition (MUGA) records are reviewed. This novel format of structure for the helical heart is then compared with historic studies of ventricular structure. New concepts will show how the basal loops cause initial isovolumetric contraction, together with factors responsible for contractile ventricular lengthening responsible for filling by suction. The interaction of these muscular-functional changes are correlated to basic studies of electrophysiology (excitation-contraction) to set the stage for alterations produced by changing the helical apex to a sphere during congestive heart failure. Macroscopic changes in heart failure, which convert the ellipse to a globe, are defined as the underpinning of dilated cardiomyopathy. It is our hypothesis that the commonality of this spheric left ventricular substrate becomes responsible for ischemic, idiopathic, and dilated ventricular cardiomyopathy.

Cardiac architecture: Gothic versus Romanesque. A cardiologist's view

The healthy left ventricle, with remarkable mechanical efficiency, has a gothic architecture, which results from the disposition of the myocardial fibers supported and maintained by a normal collagen matrix scaffold. This conclusion, arising from the analysis of roman and gothic buildings and from comparative biology of the left ventricles of different species, has been substantiated by the study of three-dimensional images obtained by MRI and analyzed with mathematic methods for measurements of the curvature and thickness of the ventricular walls. The assessment of left ventricular functional reserve based on the architecture has been very important in making therapeutic and surgical decisions in our patients and has important implications for the design of surgical strategies designed to try to improve ventricular function by restoring an architecture that allows more efficient ventricular mechanics. The structural approach and its combination with important advances in the knowledge of membrane channels, signaling pathways, cytokines, growth factors, neuroregulation, and targeted pharmacology, and with the advances in methods for reducing hemodynamic load and its cellular and structural consequences, is certain to bring about a dramatic change in the very serious and highly prevalent congestive failure associated with the Romanesque transformation of the diseased left ventricle.

The structure and function of the helical heart and its buttress wrapping. II. Interface between unfolded myocardial band and evolution of primitive heart

The unfolded myocardial band containing a central fold, extending between the pulmonary artery and aorta, has been used to explain the intact or wrapped cardiac structure, composed of a basal and apical loop forming a buttress and helix, connected to the outflow vessels of both ventricles. The interface between this simple structure, and embryologic development of the primitive heart evolving from a singular tube, into a dual pumping chamber with separate left and right sides, must be explained. The objective is to suggest that a simple and integrated triple figure-eight spiral band, with three S-shaped helixes and their apices may correlate the conventional embryologic development of the primitive heart (bulbus cordis, ventricle, and arterial outflow vessels), with the three stages of spatial orientation of the myocardial band (basal and apical loops), which extends between dual ventricular outflow vessels, in the sequence defined by the unwrapped myocardial band.

The structure and function of the helical heart and its buttress wrapping. IV. Concepts of dynamic function from the normal macroscopic helical structure

Torrent-Guasp's model of the helical heart is presented, which includes the cardiac muscular structures that produce 2 simple loops and that start at the pulmonary artery and end in the aorta. These components include a horizontal basal loop that surrounds the right and left ventricles, changes direction through a spiral fold in the ventricular band to cause a ventricular helix produced by now obliquely oriented fibers, forming a descending and ascending segment of the apical loop with an apical vortex. These anatomic concepts are successively activated to produce a sequence of narrowing by the basal loop, shortening by the descending segment, lengthening by the ascending segment, and widening in the cardiac cycle that causes ventricular ejection to empty and suction to fill. The factors responsible for internal torsional movements for cardiac output and suction are defined, together with mechanisms responsible for electromechanical activity produced during sequential changes in contraction and relaxation properties. These interactions of mechanical structure and function are defined in relation to pressure-related cardiac events observed from aortic, left ventricular, and left atrial recordings.