LV twisting and untwisting in HCM: ejection begets filling. Diastolic functional aspects of HCM

State-of-the-art methodologies used in preclinical studies to assess left ventricular diastolic and systolic function in mice, pitfalls and troubleshooting

Cardiovascular diseases (CVD) are still the leading cause of death worldwide. The improved survival of patients with comorbidities such as type 2 diabetes, hypertension, obesity together with the extension of life expectancy contributes to raise the prevalence of CVD in the increasingly aged society. Therefore, a translational research platform that enables precise evaluation of cardiovascular function in healthy and disease condition and assess the efficacy of novel pharmacological treatments, could implement basic science and contribute to reduce CVD burden. Heart failure is a deadly syndrome characterized by the inability of the heart to meet the oxygen demands of the body (unless there is a compensatory increased of filling pressure) and can manifest either with reduced ejection fraction (HFrEF) or preserved ejection fraction (HFpEF). The development and progression of HFrEF is mostly attributable to impaired contractile performance (systole), while in HFpEF the main problem resides in decreased ability of left ventricle to relax and allow the blood filling (diastole). Murine preclinical models have been broadly used in research to understand pathophysiologic mechanisms of heart failure and test the efficacy of novel therapies. Several methods have been employed to characterise cardiac systolic and diastolic function including Pressure Volume (PV) loop hemodynamic analysis, echocardiography and Magnetic Resonance Imaging (MRI). The choice of one methodology or another depends on many aspects including budget available, skills of the operator and design of the study. The aim of this review is to discuss the importance of several methodologies that are commonly used to characterise the cardiovascular phenotype of preclinical models of heart failure highlighting advantages and limitation of each procedure. Although it requires highly skilled operators for execution, PV loop analysis represents the "gold standard" methodology that enables the assessment of left ventricular performance also independently of vascular loading conditions and heart rate, which conferee a really high physiologic importance to this procedure.

Cardiac Imaging in the Athlete: Shrinking the "Gray Zone"

PURPOSE OF THE REVIEW

This review will explore frequently encountered diagnostic challenges and summarize the role cardiac imaging plays in defining the boundaries of what constitutes the athlete's heart syndrome versus pathology.

RECENT FINDINGS

Investigations have predominantly focused on differentiating the athlete's heart from potentially lethal pathological conditions that may produce a similar cardiac morphology. Guidelines have identified criteria for identifying definitive pathology, but difficulty arises when individuals fall in the gray zone of expected athletic remodeling and pathology. Transthoracic echo has traditionally been the imaging modality of choice utilizing parameters such as wall thickness, wall:volume ratio, and certain diastolic parameters. Newer echocardiogram techniques such as strain imaging and speckle tracking have potential additive utility but still need further investigation. Cardiac magnetic resonance (CMR) imaging has emerged as an additive technique to help differentiate the phenotypic overlap between these groups. Utilizing gadolinium enhancement and T1 mapping along with its excellent spatial resolution can help distinguish pathology from physiology. Both established and novel cardiac imaging modalities have been used for uncovering the at risk athletes with cardiomyopathies. The issue is of practical importance because athletes are frequently referred to the cardiologist with symptoms of fatigue, palpitations, presyncope, and/or syncope concerned about the safety of their future participation. Imaging is a key component of risk stratification and identifying normal findings of the developed athlete and those "at-risk" athletes.

Altered regional myocardial velocities by tissue phase mapping and feature tracking in pediatric patients with hypertrophic cardiomyopathy

BACKGROUND

Hypertrophic cardiomyopathy (HCM) is associated with heart failure, atrial fibrillation and sudden death. Reduced myocardial function has been reported in HCM despite normal left ventricular (LV) ejection fraction. Additionally, LV fibrosis is associated with elevated T1 and might be an outcome predictor.

OBJECTIVE

To systematically compare tissue phase mapping and feature tracking for assessing regional LV function in children and young adults with HCM and pediatric controls, and to evaluate structure-function relationships among myocardial velocities, LV wall thickness and myocardial T1.

MATERIALS AND METHODS

Seventeen pediatric patients with HCM and 21 age-matched controls underwent cardiac MRI including standard cine imaging, tissue phase mapping (two-dimensional cine phase contrast with three-directional velocity encoding), and modified Look-Locker inversion recovery to calculate native global LV T1. Maximum LV wall thickness was measured on cine images. LV radial, circumferential and long-axis myocardial velocity time courses, as well as global and segmental systolic and diastolic peak velocities, were quantified from tissue phase mapping and feature tracking.

RESULTS

Both tissue phase mapping and feature tracking detected significantly decreased global and segmental diastolic radial and long-axis peak velocities (by 12-51%, P<0.001-0.05) in pediatric patients with HCM vs. controls. Feature tracking peak velocities were lower than directly measured tissue phase mapping velocities (mean bias = 0.3-2.9 cm/s). Diastolic global peak velocities correlated moderately with global T1 (r = -0.57 to -0.72, P<0.01) and maximum wall thickness (r = -0.37 to -0.61, P<0.05).

CONCLUSION

Both tissue phase mapping and feature tracking detected myocardial velocity changes in children and young adults with HCM vs. controls. Associations between impaired diastolic LV velocities and elevated T1 indicate structure-function relationships in HCM.

Clinical-pathological correlations of BAV and the attendant thoracic aortopathies. Part 2: Pluridisciplinary perspective on their genetic and molecular origins

Bicuspid aortic valve (BAV) arises during valvulogenesis when 2 leaflets/cusps of the aortic valve (AOV) are fused together. Its clinical manifestations pertain to faulty AOV function, the associated aortopathy, and other complications surveyed in Part 1 of the present bipartite-series. Part 2 examines mainly genetic and epigenetic causes of BAV and BAV-associated aortopathies (BAVAs) and disease syndromes (BAVD). Part 1 explored the heterogeneity among subsets of patients with BAV and BAVA/BAVD, and investigated abnormal fluid dynamic stress and strain patterns sustained by the cusps. Specific BAV morphologies engender systolic outflow asymmetries, associated with abnormal aortic regional wall-shear-stress distributions and the expression/localization of BAVAs. Understanding fluid dynamic factors besides the developmental mechanisms and underlying genetics governing these congenital anomalies is necessary to explain patient predisposition to aortopathy and phenotypic heterogeneity. BAV aortopathy entails complex/multifactorial pathophysiology, involving alterations in genetics, epigenetics, hemodynamics, and in cellular and molecular pathways. There is always an interdependence between organismic developmental signals and genes-no systemic signals, no gene-expression; no active gene, no next step. An apposite signal induces the expression of the next developmental gene, which needs be expressed to trigger the next signal, and so on. Hence, embryonic, then post-partum, AOV and thoracic aortic development comprise cascades of developmental genes and their regulation. Interdependencies between them arise, entailing reciprocal/cyclical mutual interactions and adaptive feedback loops, by which developmental morphogenetic processes self-correct responding to environmental inputs/reactions. This Survey can serve as a reference point and driver for further pluridisciplinary BAV/BAVD studies and their clinical translation.

Clinical-pathological correlations of BAV and the attendant thoracic aortopathies. Part 1: Pluridisciplinary perspective on their hemodynamics and morphomechanics

Clinical BAV manifestations pertain to faulty aortic valve (AOV) function, the associated aortopathy, and other complications such as endocarditis, thrombosis and thromboembolism. BAV arises during valvulogenesis when 2 of the 3 leaflets/cusps of the AOV are fused together. Ensuing asymmetric BAV morphologies alter downstream ejection jet flow-trajectories. Based on BAV morphologies, ejection-flows exhibit different wall-impingement and scouring patterns in the proximal aorta, with excessive hydrodynamic wall-shear that correlates closely with mural vascular smooth muscle cell and extracellular matrix disruptions, revealing hemodynamic participation in the pathogenesis of BAV-associated aortopathies. Since the embryologic regions implicated in both BAV and aortopathies derive from neural crest cells and second heart field cells, there may exist a common multifactorial/polygenic embryological basis linking the abnormalities. The use of Electronic Health Records - encompassing integrated NGS variant panels and phenotypic data - in clinical studies could speed-up comprehensive understanding of multifactorial genetic-phenotypic and environmental factor interactions. This Survey represents the first in a 2-article pluridisciplinary work. Taken in toto, the series covers hemodynamic/morphomechanical and environmental (milieu intérieur) aspects in Part 1, and molecular, genetic and associated epigenetic aspects in Part 2. Together, Parts 1-2 should serve as a reference-milestone and driver for further pluridisciplinary research and its urgent translations in the clinical setting.

Morphomechanic phenotypic variability of sarcomeric cardiomyopathies: A multifactorial polygenic perspective

Morphology underlies subdivision of the primary/heritable sarcomeric cardiomyopathies (CMs) into hypertrophic (HCM) and dilated (DCM). Next-generation DNA-sequencing (NGS) has identified important disease-variants, improving CM diagnosis, management, genetic screening, and prognosis. Although monogenic (Mendelian) analyses directly point at downstream studies, they disregard coexisting genomic variations and gene-by-gene interactions molding detailed CM-phenotypes. In-place of polygenic models, in accounting for observed defective genotype-phenotype correlations, fuzzy concepts having gradations of significance and unsharp domain-boundaries are invoked, including pleiotropy, genetic-heterogeneity, incomplete penetrance, and variable expressivity. HCM and DCM undoubtedly entail cooperativity of unidentified/elusive causative genomic-variants. Modern genomics can exploit comprehensive electronic/digital health records, facilitating consideration of multifactorial variant-models. Genome-wide association studies entailing high-fidelity solid-state catheterization, multimodal-imaging, molecular cardiology, systems biology and bioinformatics, will decipher accurate genotype-phenotype correlations and identify novel therapeutic-targets, fostering personalized medicine/cardiology. This review surveys successes and challenges of genetic/genomic approaches to CMs, and their impact on current and future clinical care.

Cardiovascular magnetic resonance evaluation of symptomatic severe aortic stenosis: association of circumferential myocardial strain and mortality

BACKGROUND

It is unknown whether circumferential strain is associated with prognosis after treatment of aortic stenosis (AS). We aimed to characterise strain in severe AS, using myocardial tagging cardiovascular magnetic resonance (CMR), prior to and following Transcatheter Aortic Valve Implantation (TAVI) and Surgical Aortic Valve Replacement (SAVR), and determine whether abnormalities in strain were associated with outcome.

METHODS

CMR was performed pre- and 6 m post-intervention in 98 patients (52 TAVI, 46 SAVR; 77 ± 8 years) with severe AS. TAVI patients were older (80.9 ± 6.4 vs. 73.0 ± 7.0 years, p < 0.01) with a higher STS score (2.06 ± 0.6 vs. 6.03 ± 3.4, p < 0.001). Tagged cine images were acquired at the basal, mid and apical LV levels with a complementary spatial modulation of magnetization (CSPAMM) pulse sequence. Circumferential strain, strain rate and rotation were calculated using inTag© software.

RESULTS

No significant change in basal or mid LV circumferential strain, or of diastolic strain rate, was seen following either intervention. However, a significant and comparable decline in LV torsion and twist was observed (SAVR: torsion 14.08 ± 8.40 vs. 7.81 ± 4.51, p < 0.001, twist 16.17 ± 7.01 vs.12.45 ± 4.78, p < 0.01; TAVI: torsion 14.43 ± 4.66 vs. 11.20 ± 4.62, p < 0.001, twist 16.08 ± 5.36 vs. 12.36 ± 5.21, p < 0.001) which likely reflects an improvement towards normal physiology following relief of AS. Over a maximum 6.0y follow up, there were 23 (16%) deaths following valve intervention. On multivariable Cox analysis, baseline mid LV circumferential strain was significantly associated with all-cause mortality (hazard ratio, 1.03; 1.01-1.05; p = 0.009) independent of age, LV ejection fraction and STS mortality risk score. ROC analysis indicated a mid LV circumferential strain > -18.7% was associated with significantly reduced survival.

CONCLUSION

TAVI and SAVR procedures are associated with comparable declines in rotational LV mechanics at 6 m, with largely unchanged strain and strain rates. Pre-operative peak mid LV circumferential strain is associated with post-operative mortality.

Hypertrophic Cardiomyopathy from A to Z: Genetics, Pathophysiology, Imaging, and Management

Hypertrophic cardiomyopathy (HCM) is a heterogeneous group of diseases related to sarcomere gene mutations exhibiting heterogeneous phenotypes with an autosomal dominant mendelian pattern of inheritance. The disorder is characterized by diverse phenotypic expressions and variable natural progression, which may range from dyspnea and/or syncope to sudden cardiac death. It is found across all racial groups and is associated with left ventricular hypertrophy in the absence of another systemic or cardiac disease. The management of HCM is based on a thorough understanding of the underlying morphology, pathophysiology, and clinical course. Imaging findings of HCM mirror the variable expressivity and penetrance heterogeneity, with the added advantage of diagnosis even in cases where a specific mutation may not yet be found. The diagnostic information obtained from imaging varies depending on the specific stage of HCM-phenotype manifestation, including the prehypertrophic, hypertrophic, and later stages of adverse remodeling into the burned-out phase of overt heart failure. However, subtle or obvious, these imaging findings become critical components in diagnosis, management, and follow-up of HCM patients. Although diagnosis of HCM traditionally relies on clinical assessment and transthoracic echocardiography, recent studies have demonstrated increased utility of multidetector computed tomography (CT) and particularly cardiac magnetic resonance (MR) imaging in diagnosis, phenotype differentiation, therapeutic planning, and prognostication. In this article, we provide an overview of the genetics, pathophysiology, and clinical manifestations of HCM, with the spectrum of imaging findings at MR imaging and CT and their contribution in diagnosis, risk stratification, and therapy.

Assessment of left and right ventricular rotational interdependence: A speckle tracking echocardiographic study

OBJECTIVE

We sought to investigate the possible interdependence of the left (LV) and right ventricular (RV) rotational mechanics.

BACKGROUND

Although myocardial fiber architecture and the effect of various pathologic conditions on LV torsional mechanics have already been investigated through multiple studies using different methods, there is still a significant debate about the actual presence and functional significance of RV rotational mechanics.

METHODS

We perform a cross-sectional prospective study of 118 subjects, including 19 normal subjects (NS, 35±7 years), 34 patients with severe aortic stenosis (AS, 44±16 years), 26 patients with nonobstructive hypertrophic cardiomyopathies (HCM, 46±18), and 39 patients with nonischemic dilated cardiomyopathies (DCM, 39±13 years). LV and RV rotational parameters were measured using velocity vector imaging. Total LV and RV apical segment rotations as well as the rotation of the free wall of RV apex were measured separately. Interdependence of the LV and RV rotational mechanics was assessed using the Spearman rho test.

RESULTS

Both LV (7.3°±4.1° in NS, 11°±4.6° in AS, 7.7°±5.2° in HCM, and 1.9°±2° in DCM, P=<.0001) and RV apexes (4.7°±2° in NS, 6.1°±4° in AS, 3.2°±3.7° in HCM, and 2.4°±3.6° in DCM, P=<.0001) rotated counterclockwise in all the four study groups. Interventricular apical rotation interdependence was stronger in the AS (Spearman rho [ρ]: .716; P=.000) and in the HCM (ρ: .395; P=.04) subgroups than in the NS (ρ: .26; P=.27) and DCM (ρ: .215; P=.18). In DCM patients, RV apex rotation appeared to be independent of LV rotation. RV free wall apical rotation was larger than its corresponding value for the total apical segments in all studied groups. This difference was significant only in the AS (P=.007).

CONCLUSION

Our findings demonstrated a close correlation between RV and LV apical rotation parameters in different cardiac conditions as well as in normal subjects. However, in DCM patients, we also showed some independent rotation of the RV from the LV apex.

Genomic translational research: Paving the way to individualized cardiac functional analyses and personalized cardiology

For most of Medicine's past, the best that physicians could do to cope with disease prevention and treatment was based on the expected response of an average patient. Currently, however, a more personalized/precise approach to cardiology and medicine in general is becoming possible, as the cost of sequencing a human genome has declined substantially. As a result, we are witnessing an era of precipitous advances in biomedicine and bourgeoning understanding of the genetic basis of cardiovascular and other diseases, reminiscent of the resurgence of innovations in physico-mathematical sciences and biology-anatomy-cardiology in the Renaissance, a parallel time of radical change and reformation of medical knowledge, education and practice. Now on the horizon is an individualized, diverse patient-centered, approach to medical practice that encompasses the development of new, gene-based diagnostics and preventive medicine tactics, and offers the broadest range of personalized therapies based on pharmacogenetics. Over time, translation of genomic and high-tech approaches unquestionably will transform clinical practice in cardiology and medicine as a whole, with the adoption of new personalized medicine approaches and procedures. Clearly, future prospects far outweigh present accomplishments, which are best viewed as a promising start. It is now essential for pluridisciplinary health care providers to examine the drivers and barriers to the clinical adoption of this emerging revolutionary paradigm, in order to expedite the realization of its potential. So, we are not there yet, but we are definitely on our way.

Calcific Aortic Valve Disease: Part 1--Molecular Pathogenetic Aspects, Hemodynamics, and Adaptive Feedbacks

Aortic valvular stenosis (AVS), produced by calcific aortic valve disease (CAVD) causing reduced cusp opening, afflicts mostly older persons eventually requiring valve replacement. CAVD had been considered "degenerative," but newer investigations implicate active mechanisms similar to atherogenesis--genetic predisposition and signaling pathways, lipoprotein deposits, chronic inflammation, and calcification/osteogenesis. Consequently, CAVD may eventually be controlled/reversed by lifestyle and pharmacogenomics remedies. Its management should be comprehensive, embracing not only the valve but also the left ventricle and the arterial system with their interdependent morphomechanics/hemodynamics, which underlie the ensuing diastolic and systolic LV dysfunction. Compared to even a couple of decades ago, we now have an increased appreciation of genomic and cytomolecular pathogenetic mechanisms underlying CAVD. Future pluridisciplinary studies will characterize better and more completely its pathobiology, evolution, and overall dynamics, encompassing intricate feedback processes involving specific signaling molecules and gene network cascades. They will herald more effective, personalized medicine treatments of CAVD/AVS.

Linking Genes to Cardiovascular Diseases: Gene Action and Gene-Environment Interactions

A unique myocardial characteristic is its ability to grow/remodel in order to adapt; this is determined partly by genes and partly by the environment and the milieu intérieur. In the "post-genomic" era, a need is emerging to elucidate the physiologic functions of myocardial genes, as well as potential adaptive and maladaptive modulations induced by environmental/epigenetic factors. Genome sequencing and analysis advances have become exponential lately, with escalation of our knowledge concerning sometimes controversial genetic underpinnings of cardiovascular diseases. Current technologies can identify candidate genes variously involved in diverse normal/abnormal morphomechanical phenotypes, and offer insights into multiple genetic factors implicated in complex cardiovascular syndromes. The expression profiles of thousands of genes are regularly ascertained under diverse conditions. Global analyses of gene expression levels are useful for cataloging genes and correlated phenotypes, and for elucidating the role of genes in maladies. Comparative expression of gene networks coupled to complex disorders can contribute insights as to how "modifier genes" influence the expressed phenotypes. Increasingly, a more comprehensive and detailed systematic understanding of genetic abnormalities underlying, for example, various genetic cardiomyopathies is emerging. Implementing genomic findings in cardiology practice may well lead directly to better diagnosing and therapeutics. There is currently evolving a strong appreciation for the value of studying gene anomalies, and doing so in a non-disjointed, cohesive manner. However, it is challenging for many-practitioners and investigators-to comprehend, interpret, and utilize the clinically increasingly accessible and affordable cardiovascular genomics studies. This survey addresses the need for fundamental understanding in this vital area.

Mechanotransduction Mechanisms for Intraventricular Diastolic Vortex Forces and Myocardial Deformations: Part 2

Epigenetic mechanisms are fundamental in cardiac adaptations, remodeling, reverse remodeling, and disease. A primary goal of translational cardiovascular research is recognizing whether disease-related changes in phenotype can be averted by eliminating or reducing the effects of environmental epigenetic risks. There may be significant medical benefits in using gene-by-environment interaction knowledge to prevent or reverse organ abnormalities and disease. This survey proposes that "environmental" forces associated with diastolic RV/LV rotatory flows exert important, albeit still unappreciated, epigenetic actions influencing functional and morphological cardiac adaptations. Mechanisms analogous to Murray's law of hydrodynamic shear-induced endothelial cell modulation of vascular geometry are likely to link diastolic vortex-associated shear, torque and "squeeze" forces to RV/LV adaptations. The time has come to explore a new paradigm in which such forces play a fundamental epigenetic role, and to work out how heart cells react to them. Findings from various imaging modalities, computational fluid dynamics, molecular cell biology and cytomechanics are considered. The following are examined, among others: structural dynamics of myocardial cells (endocardium, cardiomyocytes, and fibroblasts), cytoskeleton, nucleoskeleton, and extracellular matrix; mechanotransduction and signaling; and mechanical epigenetic influences on genetic expression. To help integrate and focus relevant pluridisciplinary research, rotatory RV/LV filling flow is placed within a working context that has a cytomechanics perspective. This new frontier in cardiac research should uncover versatile mechanistic insights linking filling vortex patterns and attendant forces to variable expressions of gene regulation in RV/LV myocardium. In due course, it should reveal intrinsic homeostatic arrangements that support ventricular myocardial function and adaptability.

Mechanotransduction mechanisms for intraventricular diastolic vortex forces and myocardial deformations: part 1

Epigenetic mechanisms are fundamental in cardiac adaptations, remodeling, reverse remodeling, and disease. This two-article series proposes that variable forces associated with diastolic RV/LV rotatory intraventricular flows can exert physiologically and clinically important, albeit still unappreciated, epigenetic actions influencing functional and morphological cardiac adaptations and/or maladaptations. Taken in toto, the two-part survey formulates a new paradigm in which intraventricular diastolic filling vortex-associated forces play a fundamental epigenetic role, and examines how heart cells react to these forces. The objectives are to provide a perspective on vortical epigenetic effects, to introduce emerging ideas, and to suggest directions of multidisciplinary translational research. The main goal is to make pertinent biophysics and cytomechanical dynamic systems concepts accessible to interested translational and clinical cardiologists. I recognize that the diversity of the epigenetic problems can give rise to a diversity of approaches and multifaceted specialized research undertakings. Specificity may dominate the picture. However, I take a contrasting approach. Are there concepts that are central enough that they should be developed in some detail? Broadness competes with specificity. Would, however, this viewpoint allow for a more encompassing view that may otherwise be lost by generation of fragmented results? Part 1 serves as a general introduction, focusing on background concepts, on intracardiac vortex imaging methods, and on diastolic filling vortex-associated forces acting epigenetically on RV/LV endocardium and myocardium. Part 2 will describe pertinent available pluridisciplinary knowledge/research relating to mechanotransduction mechanisms for intraventricular diastolic vortex forces and myocardial deformations and to their epigenetic actions on myocardial and ventricular function and adaptations.

Vortex formation time is not an index of ventricular function

The diastolic intraventricular ring vortex formation and pinch-off process may provide clinically useful insights into diastolic function in health and disease. The vortex ring formation time (FT) concept, based on hydrodynamic experiments dealing with unconfined (large tank) flow, has attracted considerable attention and popularity. Dynamic conditions evolving within the very confined space of a filling, expansible ventricular chamber with relaxing and rebounding, and viscoelastic muscular boundaries diverge from unconfined (large tank) flow and encompass rebounding walls' suction and myocardial relaxation. Indeed, clinical/physiological findings seeking validation in vivo failed to support the notion that FT is an index of normal/abnormal diastolic ventricular function. Therefore, FT as originally proposed cannot and should not be utilized as such an index. Evidently, physiologically accurate models accounting for coupled hydrodynamic and (patho)physiological myocardial wall interactions with the intraventricular flow are still needed to enhance our understanding and yield diastolic function indices useful and reliable in the clinical setting.

Evaluation of left ventricular torsion in children with hypertrophic cardiomyopathy

AIMS

To evaluate the role of torsion in hypertrophic cardiomyopathy in children.

METHODS

A total of 88 children with idiopathic hypertrophic cardiomyopathy (n = 24) and concentric hypertrophy (n = 20) were investigated with speckle-tracking echocardiography and compared with age- and gender-matched healthy controls (n = 44).

RESULTS

In hypertrophic cardiomyopathy, we found increased torsion (2.8 ± 1.6 versus 1.9 ± 1.0°/cm [controls], p < 0.05) because of an increase in clockwise basal rotation (-8.7 ± 4.3° versus -4.9 ± 2.5° [controls], p < 0.001) and prolonged time to peak diastolic untwisting (3.7 ± 2.4% versus 1.7 ± 0.6% [controls] of cardiac cycle, p < 0.01), but no differences in peak untwisting velocities. Hypertrophic cardiomyopathy patients demonstrated a negative correlation between left ventricular muscle mass and torsion (r = -0.7, p < 0.001). In concentric hypertrophy, torsion was elevated because of increased apical rotation (15.1 ± 6.4° versus 10.5 ± 5.5° [controls], p < 0.05) without correlation with muscle mass. Peak untwisting velocities (- 202 ± 88 versus -145 ± 67°/s [controls], p < 0.05) were higher in concentric hypertrophy and time to peak diastolic untwisting was delayed (1.8 ± 0.8% versus 1.2 ± 0.6% [controls], p < 0.05).

CONCLUSIONS

In contrast to an increased counterclockwise apical rotation in concentric hypertrophy, hypertrophic cardiomyopathy is characterised by predominantly enhanced systolic basal clockwise rotation. Diastolic untwisting is delayed in both groups. Torsion may be an interesting marker to guide patients with hypertrophic cardiomyopathy.

Galen, father of systematic medicine. An essay on the evolution of modern medicine and cardiology

Galen (129-217) was the ultimate authority on all medical subjects for 15 centuries. His anatomical/physiological concepts remained unchallenged until well into the 17th century. He wrote over 600 treatises, of which less than one-third exist today. The Galenic corpus is stupendous in magnitude; the index of word-entries in it contains 1300 pages. Galen's errors attracted later attention, but we should balance the merits and faults in his work because both exerted profound influences on the advancement of medicine and cardiology. Galen admonished us to embrace truth as identified by experiment, warning that everyone's writings must be corroborated by directly interrogating Nature. His experimental methods' mastery is demonstrated in his researches, spanning every specialty. In his life-sustaining schema, the venous, arterial, and nervous systems, with the liver, heart, and brain as their respective centers, were separate, each distributing through the body one of three pneumata: respectively, the natural, the vital, and the animal spirits. He saw blood carried both within the venous and arterial systems, which communicated by invisible "anastomoses," but circulation eluded him. The "divine Galen's" writings, however, contributed to Harvey's singular ability to see mechanisms completely differently than other researchers, thinkers and experimentalists. Galen was the first physician to use the pulse as a sign of illness. Some representative study areas included embryology, neurology, myology, respiration, reproductive medicine, and urology. He improved the science and use of drugs in therapeutics. Besides his astounding reputation as scientist-author and philosopher, Galen was deemed a highly ethical clinician and brilliant diagnostician.

Evaluation of right and left ventricular diastolic filling

A conceptual fluid-dynamics framework for diastolic filling is developed. The convective deceleration load (CDL) is identified as an important determinant of ventricular inflow during the E wave (A wave) upstroke. Convective deceleration occurs as blood moves from the inflow anulus through larger-area cross-sections toward the expanding walls. Chamber dilatation underlies previously unrecognized alterations in intraventricular flow dynamics. The larger the chamber, the larger becomes the endocardial surface and the CDL. CDL magnitude affects strongly the attainable E wave (A wave) peak. This underlies the concept of diastolic ventriculoannular disproportion. Large vortices, whose strength decreases with chamber dilatation, ensue after the E wave peak and impound inflow kinetic energy, averting an inflow-impeding, convective Bernoulli pressure rise. This reduces the CDL by a variable extent depending on vortical intensity. Accordingly, the filling vortex facilitates filling to varying degrees, depending on chamber volume. The new framework provides stimulus for functional genomics research, aimed at new insights into ventricular remodeling.

Historical Perspective: Harvey's epoch-making discovery of the Circulation, its historical antecedents, and some initial consequences on medical practice

In Harvey's Exercitatio Anatomica de Motu Cordis et Sanguinis in Animalibus of 1628, we see the mechanisms of the Circulation worked out more or less in full from the results of experimental demonstration, virtually complete but for the direct visual evidence of a link between the minute final terminations and initial branches of the arterial and venous systems, respectively. This would become available only when the capillaries could be seen under the microscope, by Malpighi. Harvey's amazingly modern order of magnitude analysis of volumetric circulatory flow and appreciation of the principle of continuity (mass conservation), his adroit investigational uses of ligatures of varying tightness in elegant flow experiments, and his insightful deductions truly explain the movement of the blood in animals. His end was accomplished. So radical was his discovery that early in the 18th century, the illustrious Hermann Boerhaave, professor of medicine at Leyden, declared that nothing that had been written before Harvey was worthy of consideration any more. The conclusions of De Motu Cordis are unassailable and beautiful in their simplicity. Harvey's genius and tireless determination have served physiology and medicine well.

Right and left ventricular diastolic pressure-volume relations: a comprehensive review

Ventricular compliance alterations can affect cardiac performance and adaptations. Moreover, diastolic mechanics are important in assessing both diastolic and systolic function, since any filling impairment can compromise systolic function. A sigmoidal passive filling pressure-volume relationship, developed using chronically instrumented, awake-animal disease models, is clinically adaptable to evaluating diastolic dynamics using subject-specific micromanometric and volumetric data from the entire filling period of any heartbeat(s). This innovative relationship is the global, integrated expression of chamber geometry, wall thickness, and passive myocardial wall properties. Chamber and myocardial compliance curves of both ventricles can be computed by the sigmoidal methodology over the entire filling period and plotted over appropriate filling pressure ranges. Important characteristics of the compliance curves can be examined and compared between the right and the left ventricle and for different physiological and pathological conditions. The sigmoidal paradigm is more accurate and, therefore, a better alternative to the conventional exponential pressure-volume approximation.

Left ventricular twisting mechanics and exercise in healthy individuals: a systematic review

The aim of this study was to review systematically the effects of exercise on left ventricular (LV) twisting mechanics in healthy individuals. Literature searches were conducted in electronic databases for articles reporting measures of LV twisting mechanics in healthy individuals before and during/after exercise. Upon review, 18 articles were analyzed. Studies were separated by exercise type into the following four categories to allow for detailed comparisons: submaximal, prolonged endurance, maximal, and chronic endurance. Despite an overall methodological quality of low to moderate and within-group variations in exercise intensity, duration, and subject characteristics, important trends in the literature emerged. Most important, the coupling of LV systolic twisting and diastolic untwisting was present in all exercise types, as both were either improved or impaired concomitantly, highlighting the linkage between systole and diastole provided through LV twist. In addition, trends regarding the effects of age, training status, and cardiac loading also became apparent within different exercise types. Furthermore, a potential dose-response relationship between exercise duration and the degree of impairment to LV twisting mechanics was found. Although some disagreement existed in results, the observed trends provide important directions for future research. Future investigations should be of higher methodological quality and should include consistent exercise protocols and subject populations in order to minimize the variability between investigations.

Left ventricular torsion, energetics, and diastolic function in normal human aging

This study determined, for the first time, whether the effects of normal aging on systolic and diastolic left ventricular function in subjects without cardiovascular disease are related to underlying energetic defects. Cardiac magnetic resonance imaging with tissue tagging and (31)P spectroscopy was used to determine global structure, function, myocardial strains, and the phosphocreatine-to-ATP ratio (PCr/ATP) in 49 healthy subjects aged 20-69 yr. The three major abnormalities that developed with increasing age were the early filling percentage (EFP, the left ventricular volume increase from end systole to mid-diastole divided by stroke volume × 100), which decreased with age, indicating impaired early diastolic filling (r = -0.72, P < 0.0001), the torsion-to-shortening ratio (TSR, measure of subepicardial torsion exerting mechanical advantage over subendocardial shortening), which increased with age indicating relative subendocardial dysfunction (r = 0.44, P < 0.02), and the PCr/ATP (decreased with increasing age, r = -0.52, P < 0.003). EFP and TSR were strongly correlated (r = -0.63, P < 0.0001), although they were not related to PCr/ATP [EFP vs. PCr/ATP: r = 0.34, not significant (NS) and TSR vs. PCr/ATP: r = -0.3, P = NS]. In normal aging, changes in EFP and TSR likely share the same pathophysiology, although it is unlikely that energetics have a major role in the functional effects of aging.