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.

Perceval Sutureless Bioprosthesis for Degenerative Aortic Valve Stenosis: Initial Experience With 67 Patients.

OBJECTIVE: The objective of this prospective study was to evaluate the characteristics (positive and negative) of Perceval S valve in patients undergoing aortic valve replacement with a biological prosthesis. The study included 67 patients operated on at our institution and a mean follow-up period of 18 months. METHODS: From June 2016 to November 2019, 209 patients underwent aortic valve replacement with a biological prosthesis. Of these, 67 patients were included in the study based on the exclusion and inclusion criteria set before the study began. Their data were recorded during their hospital stay (preoperative, intraoperative, and early and late postoperative time). RESULTS: Fifty-four patients underwent isolated aortic valve replacement (group I) with a Perceval S prosthesis, and 13 patients had combined aortic valve replacement procedures and CABG procedures (group II). Patients were implanted with the following prosthesis sizes: S (N = 12), M (N = 18), L (N = 28), or XL (N = 9). The Perceval S valve successfully was implanted in 67 (91.8%) patients (in 6 patients, the preoperative transthoracic echocardiographic data did not coincide with intraoperative TEE and surgical measurement of the size of the annulus in the suture). Surgical approaches in patients were medial sternotomy (N = 48), mini sternotomy (N = 15), and thoracotomy through the second intercostal space to the right (N = 4). The mean clamping time of the aorta and CPB length for isolated cases was 54 and 82 minutes, respectively, and 96 and 120 minutes for combined procedures. Four (5.9%) patients died within 30 days. CONCLUSION: Early postoperative results showed that the Perceval S valve was safe. Further follow up is required to evaluate the long-term duration of patients with this bioprosthesis.

Off-Pump Plicating Ascending Aortoplasty With External Wrapping: Magnum in Parvo.

BACKGROUND: Isolated, fusiform aneurysms, exclusively affecting the tubular portion of the ascending aorta, are rare. Surgical treatment aims to change their natural course, reducing individual and cumulative risks of rupture, dissection and death. Open tubular graft replacement still remains the procedure of choice, despite significant risks. In permanent pursuit for optimal, alternative surgical strategy in high-risk patients, less invasive and off-pump plicating ascending aortoplasty with modified external Dacron graft wrapping seems to be a reliable choice. METHODS: Two (2) consecutive patients were operated on. The same preoperative calculations and slightly different operative techniques were applied regarding surgical exposure and wrapping graft orientation. Immediate and late follow-up (5 years) results were compared. RESULTS: Absolute and indexed target ascending aortic diameters remained acceptable (<2.1cm/m2 considered the upper normal range for adults). There were no significant changes in proximal and distal aortic diameters. Ascending aortic silhouette on contrast enhanced multi-detector CT was better with Dacron wrapping graft tailored to have its grooves in the longitudinal direction. Upper mini-sternotomy was quite appropriate for this procedure, from a surgical point of view, and was safe for the patient. CONCLUSIONS: Careful patient selection and using the current model of preoperative calculations and surgical technique resulted in acceptable and stable ascending aortoplasty in high-risk patients 5 years after surgery.

The Influence of High-Dose Parenteral Vitamin C on the Incidence and Severity of Postoperative Pulmonary Complications in Cardiac Surgery with Extracorporeal Circulation: A Randomized Controlled Trial.

Cardiac surgery (CS) with extracorporeal circulation (ECC), induces intense oxidative stress (OS) and systemic inflammatory response (SIR), which may seriously affect postoperative lung function. We aimed to test if high parenteral (200 mg/kg/24 h) daily doses of Vitamin C (VitC), given within 48 h after the beginning of the operation, may reduce the incidence and severity of postoperative pulmonary complications (PPCs) in CS patients. This single-center, prospective, randomized, single-blinded, interventional trial included 150 patients, assigned to control Group A (n = 75) and interventional Group B (n = 75). Group B intraoperatively received one-fourth (i.e., 50 mg/kg) of the planned daily Vit C dose, divided into three equal parts and diluted in 10 mL of normal saline, while Group A received an equal volume of normal saline at the same time frames (i.e., the induction of anesthesia, aortic cross-clamp release, and sternal closure). After 6 h from the first intraoperative dose, the following regimen was applied: Group B: 50 mg/kg, 30 min i.v. infusion of VitC in 50 mL of normal saline, every 6 h, for the next 48 h, and Group A: 30 min i.v. infusion of an equal volume of normal saline every 6 h, for the next 48 h. Modified Kroenke's score was used to determine the incidence and severity of PPCs. The overall incidence of PPCs was 36.7% and was significantly lower in Group B (13.3% vs. 60.0%, p < 0.001). The PPCs severity score was also significantly lower in Group B (1 vs. 3, p < 0.001). In addition, patients from Group B had significantly less damaged lungs, better postoperative renal function, shorter ICU stays, fewer ICU re-admissions, and lower hospital mortality. No VitC-related adverse effects were recorded. High parenteral daily VitC doses given within 48 h after the beginning of CS are safe and effective in reducing the incidence and severity of PPCs. A multicenter RCT is needed to confirm these results.

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.

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.

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.

Dabigatran - Metabolism, Pharmacologic Properties and Drug Interactions.

BACKGROUND: The superiority of dabigatran has been well proven in the standard dosing regimen in prevention of stroke and systemic embolism in patients with non-valvular atrial fibrillation (NVAF) and extended venous thromboembolism (VTE) treatment. Dabigatran, an anticoagulant with a good safety profile, reduces intracranial bleeding in patients with atrial fibrillation and decreases major and clinically relevant non-major bleeding in acute VTE treatment. However, several important clinical issues are not fully covered by currently available directions with regard to dabigatran administration. The prominent one is reflected in the fact that dynamic impairment in renal function due to dehydratation may lead to haemorragic complications on the one hand, while on the other hand glomerular hyperfiltration may be a possible cause of dabigatran subdosing, hence reducing the drug's efficacy. Furthermore, limitations of the Cockcroft-Gault formula, considered a standard equation for assessing the renal function, may imply that other calculations are likely to obtain more accurate estimates of the kidney function in specific patient populations. Method and Conclusions: Although not routinely recommended, a possibility of monitoring dabigatran in special clinical settings adds to optimization of its dosage regimens, timely perioperative care and administration of urgently demanded thrombolytic therapy, therefore significantly improving this drug's safety profile. Despite the fact that dabigatran has fewer reported interactions with drugs, food constituents, and dietary supplements, certain interactions still remain, requiring considerable caution, notably in elderly, high bleeding risk patients, patients with decreased renal function and those on complex drug regimens. Additionally, upon approval of idarucizumab, an antidote to dabigatran solution, hitherto being a major safety concern, has been finally reached, which plays a vital role in life-threatening bleeding and emergency interventions and surgery.

The helical ventricular myocardial band of Torrent-Guasp: potential implications in congenital heart defects.

The new concepts of cardiac anatomy and physiology, based on the observations made by Francisco Torrent-Guasp's discovery of the helical ventricular myocardial band, can be useful in the context of the surgical strategies currently used to manage patients with congenital heart defects. The potential impact of the Torrent-Guasp's Heart on congenital heart defects have been analyzed in the following settings: ventriculo-arterial discordance (transposition of the great arteries), double (atrio-ventricular and ventriculo-arterial) discordance (congenitally corrected transposition of the great arteries), Ebstein's anomaly, pulmonary valve regurgitation after repair of tetralogy of Fallot, Ross operation, and complex intra-ventricular malformations. The functional interaction of right and left ventricles occurs not only through their arrangements in series but also thanks to the structural spiral features. Changes in size and function of either ventricle may influence the performance of the other ventricle. The variety and complexity of congenital heart defects make the recognition of the relationship between form and function a vital component, especially when compared to acquired disease. The new concepts of cardiac anatomy and function proposed by Francisco Torrent-Guasp, based on his observations, should stimulate further investigations of alternative surgical strategies by individuals involved with the management of patients with congenital heart defects.

The helical ventricular myocardial band: global, three-dimensional, functional architecture of the ventricular myocardium.

We are currently witnessing the advent of new diagnostic tools and therapies for heart diseases, but, without serious scientific consensus on fundamental questions about normal and diseased heart structure and function. During the last decade, three successive, international, multidisciplinary symposia were organized in order to setup fundamental research principles, which would allow us to make a significant step forward in understanding heart structure and function. Helical ventricular myocardial band of Torrent-Guasp is the revolutionary new concept in understanding global, three-dimensional, functional architecture of the ventricular myocardium. This concept defines the principal, cumulative vectors, integrating the tissue architecture (i.e. form) and net forces developed (i.e. function) within the ventricular mass. Here we expose the compendium of Torrent-Guasp's half-century long functional anatomical investigations in the light of ongoing efforts to define the integrative approach, which would lead to new understanding of the ventricular form and function by linking across multiple scales of biological organization, as defined in ongoing Physiome project. Helical ventricular myocardial band of Torrent-Guasp may also, hopefully, allow overcoming some difficulties encountered in contemporary efforts to create a comprehensive mathematical model of the heart.

Towards new understanding of the heart structure and function.

Structure and function in any organ are inseparable categories, both in health and disease. Whether we are ready to accept, or not, many questions in cardiovascular medicine are still pending, due to our insufficient insight in the basic science. Even so, any new concept encounters difficulties, mainly arising from our inert attitude, which may result either in unjustified acceptance or denial. The ventricular myocardial band concept, developed over the last 50 years, has revealed unavoidable coherence and mutual coupling of form and function in the ventricular myocardium. After more than five centuries long debate on macroscopic structure of the ventricular myocardium, this concept has provided a promising ground for its final understanding. Recent validations of the ventricular myocardial band, reviewed here, as well as future research directions that are pointed out, should initiate much wider scientific interest, which would, in turn, lead to reconciliation of some exceeded concepts about developmental, electrical, mechanical and energetical events in human heart. The benefit of this, of course, would be the most evident in the clinical arena.

Systolic ventricular filling.

The evidence of the ventricular myocardial band (VMB) has revealed unavoidable coherence and mutual coupling of form and function in the ventricular myocardium, making it possible to understand the principles governing electrical, mechanical and energetical events within the human heart. From the earliest Erasistratus' observations, principal mechanisms responsible for the ventricular filling have still remained obscured. Contemporary experimental and clinical investigations unequivocally support the attitude that only powerful suction force, developed by the normal ventricles, would be able to produce an efficient filling of the ventricular cavities. The true origin and the precise time frame for generating such force are still controversial. Elastic recoil and muscular contraction were the most commonly mentioned, but yet, still not clearly explained mechanisms involved in the ventricular suction. Classical concepts about timing of successive mechanical events during the cardiac cycle, also do not offer understandable insight into the mechanism of the ventricular filling. The net result is the current state of insufficient knowledge of systolic and particularly diastolic function of normal and diseased heart. Here we summarize experimental evidence and theoretical backgrounds, which could be useful in understanding the phenomenon of the ventricular filling. Anatomy of the VMB, and recent proofs for its segmental electrical and mechanical activation, undoubtedly indicates that ventricular filling is the consequence of an active muscular contraction. Contraction of the ascendent segment of the VMB, with simultaneous shortening and rectifying of its fibers, produces the paradoxical increase of the ventricular volume and lengthening of its long axis. Specific spatial arrangement of the ascendent segment fibers, their interaction with adjacent descendent segment fibers, elastic elements and intra-cavitary blood volume (hemoskeleton), explain the physical principles involved in this action. This contraction occurs during the last part of classical systole and the first part of diastole. Therefore, the most important part of ventricular diastole (i.e. the rapid filling phase), in which it receives >70% of the stroke volume, belongs to the active muscular contraction of the ascendent segment. We hope that these facts will give rise to new understanding of the principal mechanisms involved in normal and abnormal diastolic heart function.

The impact of the metabolic syndrome on the outcome after aortic valve replacement.

OBJECTIVES: The aim of this study was to examine the influence of the metabolic syndrome on the left ventricular geometry as well as on the early and mid-time outcome in patients with aortic stenosis who underwent aortic valve replacement. METHODOLOGY: The study included 182 patients who underwent aortic valve replacement due to aortic stenosis. The metabolic syndrome was defined by the presence of at least three AHA-NHLB (American Heart Association/National Heart, Lung and Blood Institute) criteria. All the patients were followed for at least 2 years after the surgery. RESULTS: The metabolic syndrome did not influence the severity of aortic stenosis (mean gradient and aortic valve area). However, the metabolic syndrome was associated with the reduced prevalence of the normal left ventricular geometry and the increased risk of concentric left ventricular hypertrophy in patients with aortic stenosis. Among the metabolic syndrome criteria, only increased blood pressure was simultaneously associated with the short-term and mid-term outcome, independently of other risk factors. Increased fasting glucose level was an independent predictor of the only 30-day outcome after the valve replacement. The metabolic syndrome and left ventricular hypertrophy were, independently of hypertension and diabetes, associated with the 30-day outcome, as well as incidence of major cerebrovascular and cardiovascular events in the 2-year postoperative period. CONCLUSION: The metabolic syndrome does not change severity of the aortic stenosis, but significantly impacts the left ventricular remodeling in these patients. The metabolic syndrome and left ventricular hypertrophy, irrespective of hypertension and diabetes, are predictors of the short-term and mid-term outcome of patients with aortic stenosis who underwent aortic valve replacement.

A comprehensive morphometric analysis of the internal thoracic artery with emphasis on age, gender and left-to-right specific differences.

AIMS OF THE STUDY: The aim of this analysis was the morphometric description of the internal thoracic artery (ITA) with an emphasis on age, gender and left-to-right specific differences, as well as on age and atherosclerosis related changes of the elastic skeleton. METHODS: Forty eight arteries were obtained during forensic autopsies from 32 persons who had died of non-vascular causes. The following morphometric parameters were analyzed: thickness of the intima, the medial layer and the wall, the intima-to media-ratio and the elastic skeleton parameters. RESULTS: The intima thickness increases significantly with aging (ANOVA F=34.061, p⟨0.001), as does the intima-to-media ratio (ANOVA F=10.831, p⟨0.001). With aging, there is a significant increase in the thickness of the media (F=56.519; p⟨0.001) and of the wall (F=34.094; p⟨0,001). There is a significant increase in the media thickness during the development of atherosclerosis in the ITA (ANOVA F=11.848, p⟨0.001). No significant difference was found when these data were analyzed based on the left-to-right principle or depending on gender of the patients. However, the analysis of the elastic skeleton parameters indicated that the combined effects of aging, atherosclerosis and male gender lead to the degeneration of the elastic skeleton of the ITA. CONCLUSION: The grade of atherosclerosis gradually increases with aging as shown by morphometric analysis. The increase in the medial layer thickness suggests the potential for positive remodeling of the ITA during aging and atherosclerosis. The left/right position has no influence on morphometric parameters of the ITA, while male gender affects parameters of the elastic skeleton.

[Surgical angioplasty of the left main coronary artery].

INTRODUCTION: The conventional treatment for isolated stenosis of the left main coronary artery is bypass surgery (myocardial revascularization). However, the process of atherosclerosis is not arrested by myocardial revascularization and it will lead to the occlusion of the left main coronary artery. Revascularization will establish retrograde perfusion for 50-70% of the myocardium of the left ventricle. Direct surgical angioplasty of the left main coronary artery enables normal physiological perfusion of the whole myocardium and better myocardial function. OBJECTIVE: The aim of our study is to point out a new surgical approach of treating left main coronary artery stenosis. METHODS: Between October 2002 and October 2003, direct surgical angioplasty of the main left coronary artery was performed on three patients with isolated stenosis of the left main coronary artery using the anterior approach and the pericardium as a patch. The procedure was performed under total endotracheal anaesthesia and standard cardiopulmonary circulation, moderate hypothermia, anterograde St. Tomas cardioplegia and local cooling. Patients were followed clinically, echocardiographically and by load-tests. RESULTS: All three patients were without complications. In postoperative follow-up (54-68 months) neither angina pectoris nor electrocardiographically registered ischaemic changes were found. Load-tests performed every six months on all three patients were negative. CONCLUSION: Surgical angioplasty of isolated stenosis of the left main coronary artery is a preferred method for treating this type of coronary disease. Contraindications for this type of treatment are stenosis of the left main coronary artery with bifurcation and advanced calcification of the left main coronary artery.

Arquitectura de la pared ventricular. Respuesta / Ventricular mural architecture. Response

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[Surgical treatment of ishemic mitral regurgitation: repair, replacement or revascularization alone?].

INTRODUCTION: Treatment of ischemic mitral regurgitation in patients that require revascularization of myocardium is still debatable. OBJECTIVE: The aim of this study was to compare three surgical approaches: valve repair and revascularization; valve replacement and revascularization, and revascularization alone. METHODS: In 2006 and 2007 at the Institute for Cardiovascular Diseases, Clinical Centre of Serbia, Belgrade, 1,040 patients with coronary disease underwent surgery. Forty-three patients (4.3%) had also mitral insufficiency 3-4+. The patients were examined clinically, echocardiographically and haemodynamically. In group I there were 14 (32.3%) patients, in group II 16 (37.2%) patients and in group III 3 (30.5%) patients. Ninety-three per cent of patients were classified as New York Heart Association (NYHA) class III and IV, and three (7%) patients had congestive heart weakness with ejection fraction < or =30%. The decision as to surgical procedure was made by the surgeon. Postoperatively, patients were checked clinically and echocardiographically after 3, 6 and 12 months. The follow-up period was approximately 15 months (8-20). RESULTS: Hospital mortality for the whole group was 6.9% (3 patients). In group I mortality was 14.2% (2 patients), in group II 6.25% and in group III there was no mortality. Long term results, up to 15 months, showed 100% survival in groups I and II, and in group III one patient died (7.7%). CONCLUSION: Short term results upto 30 days were best in group III, but longer term results were better in groups I and II.

[Effect of hypertonic-hyperoncotic solution infusion on tissue perfusion during surgical treatment of the abdominal aorta].

BACKGROUND/AIM: Decreasing of arterial flow below the critical level leads to capillary endothelium edema and to further worsening of tissue perfusion. Hypertonic solution infusion provides mild and short plasma osmolality increasing, while colloidal solutions intensify that effect. The aim of this study was to investigate the effect of hypertonic-hyperoncotic solution (HH) on the organs perfusion during reconstructive surgical procedure on the abdominal aorta (AA). METHODS: The study included 40 patients submitted to AA reconstruction due to aneurysm or Leriche's syndrome. A clamp was put transversally to the aorta, under the outlets of the renal arterias. According to the solution received when a clamp was on the aorta, the patients were divided into two groups containing 20 patients each: the tested group (A) which received 4 ml/kg of the solution (7.2% NaCl/10% dextran), and the control group (B) which received 0.9% NaCl. The study excluded the patients with the preoperative creatinine level more than 139 micromol/l, and ejection heart fraction less than 40%. RESULTS: The mixed venous blood oxygen saturation increased from 73.3+/-7.33 to 74.95+/-6.19% in the group A, while it decreased from 65.35+/-10.39 to 62.65+/-10.42% in the group B (p = 0.001). The quantity of the provided oxygen in the group A increased significantly from 684.44+/-244.34 to 1362.45+/-2351.01 ml/min, while it decreased from 668.2+/-382.12 to 651.7+/-313.98 ml/min in the group B (p = 0.016). Alveolo-arterial difference in oxygen decreased from 23.12+/-14.74 to 21.1+/-10 mmHg in the group A, while it increased from 23.79+/-15.22 to 26.33+/-13.78 mmHg in the group B (p = 0.05). CONCLUSION: Satisfactory perfusion of organs during the AA surgery is obtained by using both HH and an isotonic solution. Due to maintaining the optimal values of the minute heart volume, saturation of vein blood blended with oxygen, and al-veolo-arterial difference in oxygen, it is recommended to use HH solution for reanimation of patients in declamping shock.