History of cardiac anatomy: A comprehensive review from the egyptians to today

From Psychostasis to the Discovery of Cardiac Nerves: The Origins of the Modern Cardiac Neuromodulation Concept

This review explores the historical development of cardiology knowledge, from ancient Egyptian psychostasis to the modern comprehension of cardiac neuromodulation. In ancient Egyptian religion, psychostasis was the ceremony in which the deceased was judged before gaining access to the afterlife. This ritual was also known as the "weighing of the heart" or "weighing of the soul". The Egyptians believed that the heart, not the brain, was the seat of human wisdom, emotions, and memory. They were the first to recognize the cardiocentric nature of the body, identifying the heart as the center of the circulatory system. Aristotle (fourth century BC) considered the importance of the heart in human physiology in his philosophical analyses. For Galen (third century AD), the heart muscle was the site of the vital spirit, which regulated body temperature. Cardiology knowledge advanced significantly in the 15th century, coinciding with Leonardo da Vinci and Vesalius's pioneering anatomical and physiological studies. It was William Harvey, in the 17th century, who introduced the concept of cardiac circulation. Servet's research and Marcello Malpighi's discovery of arterioles and capillaries provided a more detailed understanding of circulation. Richard Lower emerged as the foremost pioneer of experimental cardiology in the late 17th century. He demonstrated the heart's neural control by tying off the vagus nerve. In 1753, Albrecht von Haller, a professor at Göttingen, was the first to discover the heart's automaticity and the excitation of muscle fibers. Towards the end of the 18th century, Antonio Scarpa challenged the theories of Albrecht von Haller and Johann Bernhard Jacob Behrends, who maintained that the myocardium possessed its own "irritability", on which the heartbeat depended, and was independent of neuronal sensitivity. Instead, Scarpa argued that the heart required innervation to maintain life, refuting Galenic notions. In contemporary times, the study of cardiac innervation has regained prominence, particularly in understanding the post-acute sequelae of SARS-CoV-2 (Severe Acute Respiratory Syndrome Coronavirus 2) infection (PASC), which frequently involves cardiorespiratory symptoms and dysregulation of the intrinsic cardiac innervation. Recently, it has been recognized that post-acute sequelae of acute respiratory infections (ARIs) due to other pathogens can also be a cause of long-term vegetative and somatic symptoms. Understanding cardiac innervation and modulation can help to recognize and treat long COVID and long non-COVID-19 (coronavirus disease 2019) ARIs. This analysis explores the historical foundations of cardiac neuromodulation and its contemporary relevance. By focusing on this concept, we aim to bridge the gap between historical understanding and modern applications. This will illuminate the complex interplay between cardiac function, neural modulation, cardiovascular health, and disease management in the context of long-term cardiorespiratory symptoms and dysregulation of intrinsic cardiac innervations.

The Sun Also Rises: Tracing the evolution of humanistic values in anatomy pedagogy and research, including cadaveric acquisition practices

Anatomy has always been at the intersection of the socio-cultural and political landscape, where new ideas constantly replace older wisdom. From ancient Egyptians through the Greeks, and then the Romans, finally culminating into the European Renaissance-all the significant eras of human civilisation have left their insignia and distinct marks on the evolution of anatomical practices. Despite its utility as a tool for anatomy pedagogy and research that has proven its worth over millennia, cadaveric dissection has particularly been subject to political and social vicissitudes. A major debate about anatomical dissection lay with the ethical considerations, or its lack thereof, while acquiring corpses for demonstration in the dissection halls. From antiquity, anatomical dissection-often synonymous with medical studies-had typically been carried out on the dead bodies of executed criminals with certain laws, such as the Murder Act of 1752, facilitating such uses. Gradually, the uses of unclaimed bodies, resourced primarily from the impoverished sections of society, were also introduced. However, these body acquisition protocols often missed the crucial element of humanism and ethical considerations, while knowledge augmentation was taken as sufficient reasoning. Unfortunately, a gross disregard towards humanistic values promulgated heinous and illegal practices in acquiring corpses, including grave robbery and even murders like in the case of Burke and Hare murders of 1828. Follow-up legislation, such as the Anatomy Act of 1832, and comparable laws in other European nations were passed to curb the vile. What distils from such a historical discourse on humane values in anatomy dissection, or medical science in general, is that the growth and integration of humanism in anatomy have never been linear, but there were intermittent and, yet, significant disruptions in its timeline. For example, there were serious human rights violations in anatomical practices during the Third Reich in Germany that perpetrated the holocaust. The medical community has kept evolving and introducing new moral values and principles while using such egregious events as lessons, ultimately resulting in the Declaration of Helsinki in 1964. This article revisits the heterogeneous journey of integrating humanistic values in anatomy practice. Such humanistic traits that, like medical science, have also developed over centuries through the inputs of physicians, researchers, and philosophers-from Greece to modernity with an important stopgap at the Renaissance-are a fascinating lore that deserves to be re-envisioned through the lens of contemporary values and ethos. In parallel to human medicine, humanistic values continue to influence veterinary medicine, a welcome development, as our society condemns animal cruelty in any form. There are lessons to be learned from this historical journey of how humanism shaped many of the concepts that anatomists use now. Finally, and most importantly, it might prevent the medical community from repeating the same mistakes by cautioning against the traps that are there, and in a convoluted world where morality as such is eroding from our social fabric, will always be there. Such historical account acts as a righteous, ethical, and contextual compass to guide the existing and upcoming anatomists in discerning between light and dark, right and wrong, and roads-to be or not to be-taken.

Pulmonary valve morphometry revisited: Clinical implications for valvular and supravalvular interventions

In this cadaver-based study, we aimed to present a novel approach to pulmonary valve (PV) anatomy, morphometry, and geometry to offer comprehensive information on PV structure. The 182 autopsied human hearts were investigated morphometrically. The largest PV area was seen for the coaptation center plane, followed by basal ring and the tubular plane (626.7 ± 191.7 mm² vs. 433.9 ± 133.6 mm² vs. 290.0 ± 110.1 mm² , p < 0.001). In all leaflets, fenestrations are noted and occur in 12.5% of PVs. Only in 31.3% of PVs, the coaptation center is located in close vicinity of the PV geometric center. Similar-sized sinuses were found in 35.7% of hearts, in the remaining cases, significant heterogeneity was seen in size. The mean sinus depth was: left anterior 15.59 ± 2.91 mm, posterior: 16.04 ± 2.82 mm and right anterior sinus: 16.21 ± 2.81 mm and the mean sinus height: left anterior 15.24 ± 3.10 mm, posterior: 19.12 ± 3.79 mm and right anterior sinus: 18.59 ± 4.03 mm. For males, the mean pulmonary root perimeters and areas were significantly larger than those for females. Multiple forward stepwise regression model showed that anthropometric variables might predict the coaptation center plane (sex, age, and heart weight; R²  = 33.8%), tubular plane (sex, age, and BSA; R²  = 20.5%) and basal ring level area (heart weight and sex; R²  = 17.1%). In conclusion, the largest pulmonary root area is observed at the coaptation center plane, followed by the basal ring and tubular plane. The PV geometric center usually does not overlap valve coaptation center. Significant heterogeneity is observed in the size of sinuses and leaflets within and between valves. Anthropometric variables may be used to predict pulmonary root dimensions.

Region-dependent volumetric oscillation of self-oscillating gels with gradient transducers

Heartbeats with different ventricular contractions vary with heart regions, which can be described as anisotropy. Herein, we report self-oscillating gels which exhibit region-dependent anisotropic volumetric oscillation behavior similar to that of the heart. We installed a (Ru(bpy)₃) gradient transducer on self-oscillating gels by employing slow and unidirectional diffusion in the gels and dipping part of the gel into a Ru(bpy)₃-NHS solution. We found that the spatial distribution of Ru(bpy)₃ in the gel caused region-dependent swelling/deswelling behavior depending on the redox state. We also confirmed that gel regions with smaller Ru(bpy)₃ amounts exhibit lower amplitudes than those with larger amounts of Ru(bpy)₃ during the Belousov-Zhabotinsky (BZ) reaction. These results are important in the design of self-oscillating soft actuators or machines, such as a biomimetic pump with desirable anisotropic oscillating behavior.

Getting to the heart of rhythm: A century of progress

The human heart beats over eighty thousand times a day, and the average person's heart may have beaten up to 3 billion times by the age of 80. During the early stages of pregnancy, the heart beat provides the first visual and auditory sign of life of the foetus. Conversely, the first audible sound that the foetus is likely to hear is the heart beat of the mother. How fitting then, that at the "birth" Physiological Reviews the very first article published in 1921 written by Eyster and Meek addressed "The origin and conduction of the heart beat".¹ In their insightful review, the authors discussed the landmark discoveries made from the mid-19^th century on the electrical function of the heart. Now, a hundred years later, at the start of the next century of Physiological Reviews, an update on the huge progress made in the "exciting" field of cardiac electrophysiology is warranted. Guided by a number of excellent reviews published in Physiological Reviews since 1921 as well as a large body of literature, an overview of the important advancements made on the topic is provided here.

Right, left and cilia: How asymmetry is established

The initial breaking of left-right (L-R) symmetry in the embryo is controlled by a motile-cilia-driven leftward fluid flow in the left-right organiser (LRO), resulting in L-R asymmetric gene expression flanking the LRO. Ultimately this results in left- but not right-sided activation of the Nodal-Pitx2 pathway in more lateral tissues. While aspects of the initial breaking event clearly vary between vertebrates, events in the Lateral Plate Mesoderm (LPM) are conserved through the vertebrate lineage. Evidence from model systems and humans highlights the role of cilia both in the initial symmetry breaking and in the ability of more lateral tissues to exhibit asymmetric gene expression. In this review we concentrate on the process of L-R determination in mouse and humans.

Carbon nanotube materials for electrocardiography

Carbon nanotubes (CNTs) as 1D nanomaterials of excellent physicochemical characteristics bring hope to compete and eventually conquer traditional solutions in electrocardiography - one of the most powerful and non-invasive diagnostic tools in cardiac disorders. Our review tracks (from 2008) the development of CNTs as critical components in the systems where CNTs serve mainly as electroconductive fillers hence enable recording electrocardiographs (ECG). The characteristics of the CNT-based ECG systems - mainly to-skin electrodes and in a few cases wiring - covers their electrical and mechanical performance (adhesivity, flexibility, elasticity) and qualitative biocompatibility. By comprehensive analysis of the state-of-art in this field, we intend to indicate the most important challenges for the CNT (and other) materials to be applied in scale-up solution for electrocardiography in the near future.

Anatomic Considerations Relevant to Atrial and Ventricular Arrhythmias

Knowledge of relevant cardiac anatomy is crucial in understanding the pathophysiology and treatment of arrhythmias, and helps avoid potential complications in mapping and ablation. This article explores the anatomy, relevant to electrophysiologists, relating to atrial flutter and atrial fibrillation, ventricular tachycardia relating to the outflow tracts as well as endocardial structure, and also epicardial considerations for mapping and ablation.

What's in a cardiomyocyte - And how do we make one through reprogramming?

Substantial progress is being made in the field cardiac reprogramming, and those in the field are hopeful that the technology will be formulated for therapeutic use. Beyond the excitement around generating a revolutionary new approach for treating ischemic heart diseases, cardiac reprogramming has delivered provocative findings that challenge common notions of cell fate and cell identity. Have we really made de novo cardiomyocytes? To answer this question, the essential characteristics of this unique and important cell type must first be defined. In this review, we walk through the history of scientific inquiry into cardiomyocytes, and then we examine the core features of cardiomyocytes as detailed in modern definitions. Informed by this, we turn to cardiac reprogramming to analyze the various screening approaches and ultimate factor combinations used in each study. We follow this with a dissection of the evidence used to support the authors' claims of successfully creating cardiomyocytes, and we end by discussing what is known about the molecular mechanisms of cardiac reprogramming. Through this analysis, we find interesting differences between the study designs and their results, but it becomes clear that the field at large is generating cells that closely match the textbook definition cardiomyocyte. However, the differences noted between the results of each study are largely unexplained, reflecting the need for further research in both cardiac reprogramming and in native cardiomyocyte biology. Knowledge gained from future research will help move the field towards better reprogramming techniques and technologies.

Jaw pain and myocardial ischemia: A review of potential neuroanatomical pathways

Cardiac pain is usually manifested as a crushing, squeezing, or sensation of pressure in the center of the chest. The pain can be referred to the left shoulder, neck, jaw, and epigastric region as well as the temporomandibular region, paranasal sinuses, and head in general. Although not well understood, during myocardial ischemia, the process of cardiac referred pain to craniofacial structures can be explained by the convergence of visceral and somatic relays at the trigeminal nucleus in the brain stem. The goal of this article is to review the possible pathways for referred jaw pain due to myocardial ischemia. Clin. Anat. 32:476-479, 2019. © 2019 Wiley Periodicals, Inc.

Gerbode defect: A comprehensive review of its history, anatomy, embryology, pathophysiology, diagnosis, and treatment

The purpose of this paper is to survey the literature on Gerbode defect and provide an overview of its history, anatomy, development, pathophysiology, diagnosis, and treatment options. The available literature on this topic, including case reports, was thoroughly reviewed. Gerbode defect is defined as abnormal shunting between the left ventricle and right atrium resulting from either a congenital defect or prior cardiac insults. The pathophysiology underlying the development of Gerbode defect is a disease process that injures the atrioventricular septum and leads to the abnormal shunting of blood. Although the most prevalent cause of Gerbode defect has historically been congenital, an increasing trend towards acquired cases has recently been reported owing to improved diagnostic capabilities and a greater number of invasive cardiac procedures. In conclusion, Gerbode defect is an increasingly recognized condition that warrants further study.

Auscultation of the heart: The Basics with Anatomical Correlation

Proficiency in heart auscultation continues to be important even in an era of modern technology. However, many physicians and health care providers are uncomfortable and often inaccurate in their ability to identify normal and abnormal heart sounds. The following review was performed to provide a basis that health care providers can use to strengthen their understanding and improve their techniques when auscultating the human heart. Clin. Anat. 30:58-60, 2017. © 2016 Wiley Periodicals, Inc.