The membranous septum revisited: A glimpse of our anatomical past.

The so-called membranous septum is the fibrous component of the septal structures within the heart. It is relatively subtle in its appearance, but of considerable significance to the understanding of cardiac function and cardiac disease, both congenital and acquired. Surprisingly, its existence was seemingly unknown until the early decades of the 19th century. At this time, those writing in the English language described it as the "undefended space," recognizing its importance in the setting of its aneurysmal dilation, and as the site of septal defects. By the initial decade of the 20th century, it had come to be recognized as the landmark to the site of atrioventricular bundle. Over the first decade of the 21st century, its clinical significance has been emphasized in the context of transcutaneous replacement of the aortic valve. In this review, we describe our own recent investigations of this fibrous part of the septal structures. At the same time, we provide a glimpse of our anatomic past, explaining how its initial description relied on the observations of young physicians taking their first steps in the investigation of cardiac anatomy.

Presence of the annular ridge and location of the coronary sinus ostium as morphological features ofthe right atrium and interatrial septum in healthy common marmosets (Callithrix jacchus).

To effectively use a common marmoset (Callithrix jacchus) as an experimental animal species, it is critical to establish a normal characteristics and morphology of the organs of the common marmoset. Although gross morphology of the common marmoset heart is reportedly the same as that of humans, little information is available regarding detailed morphology of the right atrium and the interatrial septum. Heart specimens were collected from three male and 10 female marmosets aged 9 to 65 months to determine the morphological features of the right atrium and the interatrial septum. Ten specimens were evaluated morphologically with a stereoscopic microscope in accordance with preparation and investigation methods designed to facilitate evaluation. Three specimens were histologically evaluated after being stained with hematoxylin-eosin, Elastica van Gieson and periodic acid Schiff. An annular ridge that is not present in the human heart was present in the right atrium and the interatrial septum of the common marmoset hearts. Tissue structure of the annular ridge was similar to atrial myocardial fibers. Furthermore, location of the coronary sinus ostium was different to that in humans. Present findings were used to create a schematic view of the annular ridge in the common marmoset heart. In the common marmoset heart, the annular ridge may function as a valve of the superior vena cava ostium, inferior vena cava ostium, and coronary sinus ostium. Present study provides morphological evidence that common marmosets have a valve-like structure in the right atrium.

Intra-procedural evaluation of the cavo-tricuspid isthmus anatomy with different techniques: comparison of angiography and intracardiac echocardiography.

Cavo-tricuspid isthmus (CTI) anatomies are highly variable, and specific anatomies lead to a difficult CTI ablation. This study aimed to compare the clinical utility of angiography and intracardiac echocardiography (ICE) in evaluating CTI anatomies, and to investigate the impact of the CTI anatomy on the procedure when the ablation tactic was adjusted to the anatomy. This study included 92 consecutive patients who underwent a CTI ablation. The CTI morphology was assessed with both right atrial angiography and ICE before the ablation, and the ablation tactic was adjusted to the anatomy. The mean CTI length was 34 ± 9 mm. On ICE imaging, 21 (23%) patients had a flat CTI, while 41 (45%) had a concave CTI with a mean depth of 5.6 ± 2.7 mm. The remaining 30 (32%) had a distinct pouch with a mean depth of 6.4 ± 2.3 mm, located at the posterior, middle, and anterior isthmus in 15, 14, and 1 patients, respectively. The Eustachian ridge (ER) was visualized in 46 (50%) patients. On angiography, a pouch and ER were detected in 22 and 15 patients, but not in the remaining 8 and 31, respectively. A complete CTI block line was created in all patients without any complications. The CTI anatomy did not significantly impact any procedural parameters. ICE was superior to angiography in evaluating the detailed CTI anatomy, especially pouches and the ER. An adjustment of the ablation tactic to the anatomy could overcome the procedural difficulties of the CTI ablation in cases with specific anatomies.

The artery of Mouchet: blood supply of the septomarginal trabecula in 50 human hearts.

The septomarginal trabecula is a muscular structure which transmits the right branch of the atrioventricular bundle. It is usually supplied by a branch from the second anterior septal artery. Anastomoses between the right and left coronary arteries may happen on the septomarginal trabecula. They are of great significance in order to prevent ischemia during a myocardial infarction. Surgeries such as Konno's and Ross' procedures implies in knowledge of these vessels anatomy. The coronary arteries of 50 human hearts were injected with latex and subsequentely dissected with the purpose of identifying the arterial branch that supplied the septomarginal trabecula. The trabecular branch arose from the second anterior septal artery in 38% of cases, and the branch arose from the first anterior septal artery in 26%. One of the hearts had its septomarginal trabecula supplied by the conus arteriosus arteryliterature. Anastomoses between the right and left coronary arteries were found inside the septomarginal trabecula. The right branch of the atrioventricular bundle is subject to a great number of clinical conditions and is often manipulated during surgery, thus, the study of the septal branches of the coronary arteries and the trabecular branch is essential.

The artery of Mouchet: blood supply of the septomarginal trabecula in 50 human hearts

SUMMARY The septomarginal trabecula is a muscular structure which transmits the right branch of the atrioventricular bundle. It is usually supplied by a branch from the second anterior septal artery. Anastomoses between the right and left coronary arteries may happen on the septomarginal trabecula. They are of great significance in order to prevent ischemia during a myocardial infarction. Surgeries such as Konno's and Ross' procedures implies in knowledge of these vessels anatomy. The coronary arteries of 50 human hearts were injected with latex and subsequentely dissected with the purpose of identifying the arterial branch that supplied the septomarginal trabecula. The trabecular branch arose from the second anterior septal artery in 38% of cases, and the branch arose from the first anterior septal artery in 26%. One of the hearts had its septomarginal trabecula supplied by the conus arteriosus arteryliterature. Anastomoses between the right and left coronary arteries were found inside the septomarginal trabecula. The right branch of the atrioventricular bundle is subject to a great number of clinical conditions and is often manipulated during surgery, thus, the study of the septal branches of the coronary arteries and the trabecular branch is essential.

RESUMO A trabécula septomarginal é uma estrutura muscular que transmite o ramo direito do feixe atrioventricular. É usualmente suprida por um ramo da segunda artéria septal anterior. Anastomoses entre as artérias coronárias direita e esquerda podem ocorrer na trabécula. São de grande significância especialmente na prevenção de isquemia durante um infarto do miocárdio. Procedimentos cirúrgicos como o de Konno's e Ross implicam conhecimento anatômico desses vasos. As artérias coronárias de 50 corações humanos foram injetadas com látex e dissecadas com o propósito de identificar o ramo arterial que supria a trabécula septomarginal. Em somente 38% dos casos o ramo foi proveniente da segunda artéria septal anterior, enquanto que em 26% dos casos a artéria se originou da primeira septal anterior. Um dos corações teve a trabécula septomarginal suprida por um ramo originário da artéria do cone arterioso. Além disso, foram encontradas anastomoses entre as artérias coronárias no interior da trabécula septomarginal. Em suma, o ramo direito do feixe atrioventricular está sujeito a inúmeras condições clínicas e é alvo de manuseio em cirurgias, logo, o estudo dos ramos septais das artérias coronárias, em especial o ramo trabecular é essencial.

Effect of Septoplasty on Cardiopulmonary Functions in the Patients With Nasal Obstruction.

OBJECTIVE: In this study, the authors aimed to investigate whether septoplasty has an effect on cardiopulmonary functions in the patients with nasal obstruction. METHODS: A total of 53 patients with nasal obstruction due to septum deviation were included in the study. All the patients were performed septoplasty operation. Echocardiography and spirometric analysis were performed to assess cardiopulmonary functions before and after the operation (6 months postoperatively). The same evaluation was done for the degree of nasal obstruction by visual analogue scale. The preoperative and postoperative values were compared with each other. RESULTS: Of the total 53 patients, 44 were males (83%) and 9 were female (17%). The mean age was 31.71 ±â€Š9.46. The preoperative and postoperative mean right ventricular volumes were 2.0736 and 2.0906, respectively. The preoperative and postoperative mean left ventricular volumes were 4.4264 and 4.3528, respectively. The preoperative and postoperative mean cardiac septal thicknesses were 0.9642 and 0.9358, respectively. The mean value of preoperative cardiac posterior wall thicknesses was 0.8849, whereas the postoperative value was measured as 0.8340. The preoperative and postoperative mean pulmonary artery pressures were 27.8302 mmHg and 23.6415, respectively, and this was statistically significant (P < 0.001). The preoperative and postoperative mean forced vital capacities (FVC) were 4.3221 and 4.5564, respectively, and this was statistically significant (P < 0.001). The preoperative and postoperative mean 1st second forced expiratory volumes (FEV1) were 3.6698 and 3.8085, respectively, and this was statistically significant (P < 0.001). The mean value of preoperative FEV1/FVC was 84.9811, whereas postoperative mean value was measured as 83.8019 and this was statistically significant (P < 0.001). CONCLUSION: In this study, the authors observed that septoplasty has positive effect on cardiopulmonary functions in the patients with nasal obstruction due to nasal septum deviation. The authors also claim that septoplasty may be a preventive procedure for future pathologies of cardiopulmonary functions.

Comparison of Echocardiographic Parameters Between Healthy Highlanders in Tibet and Lowlanders in Beijing.

Yang, Ying, Duo-Ji Zha-Xi, Wei Mao, Guang Zhi, Bin Feng, and Yun-Dai Chen. Comparison of echocardiographic parameters between healthy highlanders in Tibet and lowlanders in Beijing. High Alt Med Biol. 19:259-264, 2018.-The hearts of highlanders exhibit distinct features compared with the hearts of lowlanders. However, previous findings have not been verified in a large-scale Tibetan population study. The aim of this study was to present differences in echocardiography results among healthy native Tibetans, acclimatized Han highlanders, and Han lowlanders at sea level. A total of 1820 healthy Tibetans and 224 healthy Han highlanders were drawn from a representative sample of residents in Tibet. Echocardiography was performed on each participant at the sampled local medical centers. Echocardiographic data from 2332 healthy Han lowlanders were obtained from a database of a medical examination center in Beijing. Using propensity score matching to balance differences in demographic features, we evaluated the effects of altitude and ethnicity in three paired comparisons. The results revealed that the great arteries were larger in the Han population than in the Tibetan population regardless of altitude (all p < 0.05). No differences were found in the right atrium between different altitudes and ethnicities. The diameters and thicknesses of the right ventricle (RV) were larger in the Tibetans than in the Han lowlanders (i.e., 30.0 mm (26.0, 34.0) versus 28.6 mm (25.5, 31.8) for the basal right ventricular linear dimension). The left heart in diastole was largest in the Han lowlanders (i.e., 46.3 ± 3.9 mm versus 43.0 mm [40.0, 44.0] in Han highlanders and 45.8 mm [43.0, 48.8] versus 42.0 mm [39.0, 45.0] in Tibetans for the diameter of the left ventricle [LV] at end-diastole). Moreover, the interventricular septum was thicker in the high-altitude population than in the low-altitude population (all p < 0.05). Compared with the Tibetans, the Han highlanders exhibited enhanced ventricular functions (65.0% [60.0, 69.0] versus 68.0% [63.0, 69.0] for LV ejection fraction and 22.0 mm [20.0, 26.0] versus 24.0 mm [21.0, 27.0] for tricuspid annular plane systolic excursion, both p < 0.05). In conclusion, a small left heart and a large RV may be consequences of hypoxic exposure at high altitudes irrespective of ethnic origin.

Development of a 3-D printing-based cardiac surgical simulation curriculum to teach septal myectomy.

OBJECTIVE: We sought to develop a 3-D printing-based simulator for teaching extended septal myectomy to trainees in cardiothoracic surgery (clinical postgraduate year 4-7). This procedure is difficult to teach because of generally unfamiliar and highly variable anatomy, limited visibility for the assistant, and significant potential complications. METHODS: A curriculum using multimedia didactics and 3-D print-based patient-specific surgical simulation was implemented. Six identical 3-D prints were constructed for each of 5 consecutive patients. Preoperative septal myectomy was performed on each printed heart by an attending surgeon and 5 residents. Model myectomy specimen volumes were measured according to liquid displacement. All print resections were videotaped and blindly evaluated by 3 attending surgeons. Pre- and post-test evaluations, and a survey tool were also used to evaluate the curriculum. RESULTS: Baseline myectomy resection volumes differed significantly (attending 15 cm3 vs resident 3.1 cm3; P < .05). Residents resected increasingly larger volumes of tissue over the course of the study. Initial resection volume (compared with faculty) increased by 0.82 cm3 per resection (95% confidence interval, 0.37-1.3 cm3; P < .0001). Total resection volume (compared with faculty) increased by 3.6 cm3 per resection (95% confidence interval, 2.4-4.9 cm3; P < .0001). The residents' survey assessment of the simulator was favorable. CONCLUSIONS: A patient-specific 3-D printing-based simulation module shows promise as a tool to augment and improve cardiothoracic resident training in septal myectomy. The residents were quickly able to perform resections on par with the attending. Residents rated the simulator favorably. Each resident benefited by experiencing the variable anatomy of 5 separate patient-specific models.

Anatomy of the coronary artery and cardiac vein in the quail ventricle: patterns are distinct from those in mouse and human hearts.

Coronary vessel development has been investigated in avian and mouse embryonic hearts. Quail embryos are a useful tool to examine vascular development, particularly because the QH1 antibody and transgenic quail line, Tg (tie1:H2B-eYFP), are useful to trace endothelial cells. However, there are only a few descriptions of the quail coronary vessels. Using ink injection coronary angiography, we examined the course of coronary vessels in the fetal quail heart. The major coronary arteries were the right and left septal arteries, which, respectively, branched off from the right and left coronary stems. The right septal artery ran posteriorly (dorsally) and penetrated the ventricular free wall to distribute to the posterior surface of the ventricles. The left septal artery ran anteriorly (ventrally) and penetrated the ventricular free wall to distribute to the anterior surface of the ventricles. The right and left circumflex arteries were directed posteriorly along the atrioventricular sulci. The cardiac veins consisted of three major tributaries: the middle, great, and anterior cardiac veins. The middle cardiac vein ascended along the posterior interventricular sulcus and emptied into the right atrium. The great cardiac vein ran along the anterior interventricular sulcus, entered the space between the left atrium and conus arteriosus and emptied into the right atrium behind the aortic bulb. The anterior cardiac vein drained the anterior surface of the right ventricle and connected to the anterior base of the right atrium. The course of coronary vessels in the quail heart was basically the same as that observed in chick but was different from those of mouse and human.

The structure of the vascular system of the septomarginal trabecula in the heart of an adult.

BACKGROUND: In cardiology, the paths of the arteries penetrating the septomarginal trabecula (SMT) are especially important. They provide blood supply to the apparatus of the right atrioventricular orifice and often form anastomoses with the system of the right coronary artery. Despite this, only a few publications discuss the morphological aspect of the septomarginal trabecula, and available histological analyses seldom deal with its blood supply. OBJECTIVES: The aim of this study was to analyze the vessel structure of the septomarginal trabecula in terms of the variability of the area of the cross-section of the lumen and the muscular layer of the artery. MATERIAL AND METHODS: The study was carried out on the material of 50 human hearts from adults of both sexes. The material was divided into 4 morphological types. Histological examinations were conducted by means of classic staining methods. RESULTS: At the initial cross-section of the septomarginal trabecula, the area of the cross-section increased to half of the length of the trabecula, and then it started to decrease. This is connected with the thickening of the inner muscular layer of the artery, which proportionally takes up more area of the cross-section of the whole artery of the SMT. The total area of the cross-section of all vessels in both types examined was also the largest in the middle part of the SMT. Furthermore, the results of this study confirm the presence of a connection between both systems of coronary arteries. CONCLUSIONS: As the septomarginal trabecula passes through the lumen of the right ventricle, its arteries become exposed to the influence of the factors which may evoke a biological response from the walls of this vessel, causing the thickening of the muscular layer and, as a result, of the section of the whole artery, in particular its middle part.

Porcine heart interatrial septum anatomy.

BACKGROUND: The left-sided atrial septal pouch (SP), a recently re-discovered anatomical structure within the human interatrial septum, has emerged as a possible source of thrombi formation and a trigger for atrial fibrillation, thereby potentially increasing the risk for ischemic stroke. In many studies, the swine interatrial septum has been used as model of the human heart. Also, possible new strategies and devices for management of the SPs may first be tested in this pig model. Therefore, in this study, we aimed to evaluate swine interatrial septum morphology and to compare it with the human analog, especially in the light of SP occurrence. METHODS: A total of 75 swine (Sus scrofa f. domestica) hearts were examined. The interatrial septum morphology was assessed, and SPs were measured. RESULTS: The most common variant of the interatrial septum was smooth septum (26.6%) followed by the patent foramen ovale channel and right SP (both 22.7%). No left or double SPs were observed. In 28.0% of all cases the fold of tissue (left septal ridge) was observed on the left side of the interatrial septum in the location where the left-sided SP should be expected. The mean length of the patent foramen ovale channel was 7.1±1.5mm. The mean right SP depth was 6.3±2.2mm, and its ostium width and height were 5.8±1.2 and 5.3±1.6mm, respectively. CONCLUSIONS: There are significant differences between human and porcine interatrial septum morphology that should be taken into account during experimental studies. The absence of the left SP in swine results in the inability to use porcine heart as an experimental model for left-sided SP management.

Variations in rotation of the aortic root and membranous septum with implications for transcatheter valve implantation.

OBJECTIVE: It is intuitive to suggest that knowledge of the variation in the anatomy of the aortic root may influence the outcomes of transcatheter implantation of the aortic valve (TAVI). We have now assessed such variation. METHODS: We used 26 specimens of normal hearts and 78 CT data sets of adults with a mean age of 64±15 years to measure the dimensions of the membranous septum and to assess any influence played by rotation of the aortic root, inferring the relationship to the atrioventricular conduction axis. RESULTS: The aortic root was positioned centrally in the majority of both cohorts, although with significant variability. For the cadaveric hearts, 14 roots were central (54%), 4 clockwise-rotated (15%) and 8 counterclockwise-rotated (31%). In the adult CT cohort, 44 were central (56%), 21 clockwise-rotated (27%) and 13 counterclockwise-rotated (17%). A mean angle of 15.5° was measured relative to the right fibrous trigone in the adult CT cohort, with a range of -32° to 44.7°. The dimensions of the membranous septum were independent of rotation. Fibrous continuity between the membranous septum and the right fibrous trigone increased with counterclockwise to clockwise rotation, implying variation in the relationship to the atrioventricular conduction axis. CONCLUSIONS: The central fibrous body is wider, providing greater fibrous support, in the setting of clockwise rotation of the aortic root. Individuals with this pattern may be more vulnerable to conduction damage following TAVI. Knowledge of such variation may prove invaluable for risk stratification.

[ANATOMICAL CHARACTERISTICS OF SEPTOMARGINAL TRABECULA OF THE RIGHT VENTRICLE OF THE HUMAN FETAL HEART].

Anatomical structure of right ventricular septomarginal trabecula (SMT) was studied at micro-macroscopical level in 99 preparations of human fetal heart formed without malformations and minor abnormalities, obtained at 17­28 weeks of development. SMT was found to be a constant cardiac structure consisting of the body and two branches: anterior and posterior. Body of SMT is a myocardial vallum, unseparable from the interventricular septum, the long axis of which is always located along the conventional line connecting septal insertion of supraventricular crest and right ventricular apex. Posterior margin of SMT body was distinct in 75% of cases and smoothened in 21.9%. Base of the SMT was solid in 46.3% and split into secondary trabeculae in 52.6% of cases. Narrow and wide forms of SMT body were considered as its extreme anatomical variants. It is suggested to distinguish two anatomical types of SMT: a complete type, in which SMT was represented by a complex consisting of body in the form of muscular vallum and both branches, and an incomplete one, in which one of the branches was absent. Human fetal heart SMT is characterized by a variability, which is manifested by certain combinations of anatomic variants of SMT base form, its posterior margin, and the presence, shape and mutual location of its branches.

Clinical cardiac structural anatomy reconstructed within the cardiac contour using multidetector-row computed tomography: Atrial septum and ventricular septum.

Cardiologists are increasingly becoming involved in procedures associated with the atrial septum and ventricular septum, such as transseptal puncture and selective site pacing. Moreover, detailed knowledge about the architecture of the atrial septum and ventricular septum is now available from studies by radiologists and anatomists. However, from the viewpoint of clinical cardiologists, many questions about the three-dimensional cardiac structural anatomy that relate closely to routine invasive procedures remain unresolved. Although modern multidetector-row computed tomography could provide answers, interventional cardiologists might have not considered the potential of this equipment, as only a few have performed studies with both radiological imaging and cadaveric hearts. Detailed knowledge of the three-dimensional fluoroscopic cardiac structural anatomy could help to reduce the need for contrast medium injection and radiation exposure, and to perform safe interventions. In this article, we present a series of cardiac structural images, including images of the atrial septum and ventricular septum, reconstructed in combination with the cardiac contour using multidetector-row computed tomography. We also discuss the clinical implications of the findings on the basis of accumulated insights of research pioneers. We hope that the present images will serve as a bridge between the fields of cardiology, radiology, and anatomy, and encourage cardiologists to integrate their accumulated insights into the three-dimensional clinical images of the living heart.

Prosthetic Valve Escaping During Transcatheter Aortic Valve Implantation.

We performed transapical transcatheter aortic valve implantation on an 87-year-old woman with severe aortic valve stenosis. Because of the narrow left ventricular outflow tract, annular positioning of the prosthetic valve proved challenging. During positioning, the prosthetic valve was accidentally dislodged from the balloon catheter and dropped into the left ventricle. Attempted catheter retrieval was unsuccessful. We therefore converted to open surgery without delay. After aortotomy, to our surprise, the prosthesis could not be found, neither in the left ventricle nor in the ascending aorta. Transesophageal echocardiography failed to reveal the location of the missing prosthesis. Fluoroscopy finally displayed the prosthesis in the descending aorta at the level of the left atrium. We proceeded with aortic and mitral valve replacement and closed the sternum. Under fluoroscopic guidance, the prosthetic valve was secured to the wall of the abdominal aorta in an infrarenal position by dilatation with a balloon catheter. This case shows that we should be alert to septum hypertrophy or a narrow left ventricular outflow tract during transapical aortic valve implantation. In such anatomical situations, we recommend advancing the sheath of the application system directly below the annular plane and positioning the prosthesis from this point.

Galen's (130-201 AD) Conceptions of the Heart.

In the 2nd century AD, the prolific Greek physician Galen contributed significantly to the anatomical and physiological knowledge of the cardiovascular system. However his erroneous theory of blood circulation, based on the inaccurate notion that venous blood passes through tiny pores in the heart's septum, moves from the right ventricle to the left, and is mixed with inhaled air from the lungs, was to block any new ideas in this field for more than 1500 years.

Clarifying the morphology of the ostium primum defect.

The 'ostium primum' defect is still frequently considered to be the consequence of deficient atrial septation, although the key feature is a common atrioventricular junction. The bridging leaflets of the common atrioventricular valve, which are joined to each other, are depressed distal to the atrioventricular junction, and fused to the crest of the muscular ventricular septum, which is bowed in the concave direction towards the ventricular apex. As a result, shunting across the defect occurs between the atrial chambers. These observations suggest that the basic deficiency in the 'ostium primum' defect is best understood as a product of defective atrioventricular septation, rather than an atrial septal defect. We have now encountered four examples of 'ostium primum' defects in mouse embryos that support this view. These were identified from a large number of mouse embryo hearts collected from a normal, outbred mouse colony and analysed by episcopic microscopy as part of an ongoing study of normal mouse cardiac development. The abnormal hearts were identified from embryos collected at embryonic days 15.5, 16.5 and 18.5 (two cases). We have analysed the features of the abnormal hearts, and compared the findings with those obtained in the large number of normally developed embryos. Our data show that the key feature of normal atrioventricular septation is the ventral growth through the right pulmonary ridge of a protrusion from the dorsal pharyngeal mesenchyme, confirming previous findings. This protrusion, known as the vestibular spine, or the dorsal mesenchymal protrusion, reinforces the closure of the primary atrial foramen, and muscularises along with the mesenchymal cap of the primary atrial septum to form the ventro-caudal buttress of the oval foramen, identified by some as the 'canal septum'. Detailed analysis of the four abnormal hearts suggests that in each case there has been failure of growth of the vestibular spine, with the result that the common atrioventricular junction found earlier during normal development now persists during cardiac development. Failure of separation of the common junction also accounts for the trifoliate arrangement of the left atrioventricular valve in the abnormal hearts. Analysis of the episcopic datasets also permits recognition of the location of the atrioventricular conduction axis. Comparison of the location of this tract in the normal and abnormal hearts shows that there is no separate formation of a ventricular component of the 'canal septum' as part of normal development. We conclude that it is abnormal formation of the primary atrial septum that is the cause of so-called 'secundum' atrial septal defects, whereas it is the failure to produce a second contribution to atrial septation (via growth of the vestibular spine) that results in the 'ostium primum' defect.

Evolution and development of ventricular septation in the amniote heart.

During cardiogenesis the epicardium, covering the surface of the myocardial tube, has been ascribed several functions essential for normal heart development of vertebrates from lampreys to mammals. We investigated a novel function of the epicardium in ventricular development in species with partial and complete septation. These species include reptiles, birds and mammals. Adult turtles, lizards and snakes have a complex ventricle with three cava, partially separated by the horizontal and vertical septa. The crocodilians, birds and mammals with origins some 100 million years apart, however, have a left and right ventricle that are completely separated, being a clear example of convergent evolution. In specific embryonic stages these species show similarities in development, prompting us to investigate the mechanisms underlying epicardial involvement. The primitive ventricle of early embryos becomes septated by folding and fusion of the anterior ventricular wall, trapping epicardium in its core. This folding septum develops as the horizontal septum in reptiles and the anterior part of the interventricular septum in the other taxa. The mechanism of folding is confirmed using DiI tattoos of the ventricular surface. Trapping of epicardium-derived cells is studied by transplanting embryonic quail pro-epicardial organ into chicken hosts. The effect of decreased epicardium involvement is studied in knock-out mice, and pro-epicardium ablated chicken, resulting in diminished and even absent septum formation. Proper folding followed by diminished ventricular fusion may explain the deep interventricular cleft observed in elephants. The vertical septum, although indistinct in most reptiles except in crocodilians and pythonidsis apparently homologous to the inlet septum. Eventually the various septal components merge to form the completely septated heart. In our attempt to discover homologies between the various septum components we aim to elucidate the evolution and development of this part of the vertebrate heart as well as understand the etiology of septal defects in human congenital heart malformations.

Impact of interatrial septum anatomic features on short- and long-term outcomes after transcatheter closure of patent foramen ovale: single device type versus anatomic-driven device selection strategy.

BACKGROUNDS: We reported the short- and long-term results of our institutional single center registry Interatrial Septum Interventions Study (ISIS) about the impact of different anatomic characteristics and related device selection in patent foramen ovale (PFO) closure. METHODS: Over a 9 year period (September 2003-September 2012) we prospectively enrolled 340 consecutive patients (mean age 44 ± 15. 5 years, 198 females) who had been referred to our center for PFO catheter-based closure. The first 105 patients received a single type of device independently from the anatomy (single device strategy). The remaining 235 patients received a different device based on intracardiac echocardiographic study of interatrial septum anatomy (anatomic strategy). RESULTS: Immediate success rate was 100% in both groups, whereas the rate of immediate complications was 10.4% and 2.5% (P<0.01) in the single strategy group and anatomic strategy group, respectively. During a mean follow-up of 59.3 ± 28.9 months, the occlusion rate was 86.6% and 94%, whereas the incidence of recurrences was 1.8% and 0% in the single device strategy group and anatomic strategy group, respectively. CONCLUSION: The results from ISIS registry showed that anatomy of interatrial septum associated with PFO is quite complex leading to an increased rate of complications and a slightly lower closure rate if treated with a single device strategy.

The new patent foramen ovale occluder FIGULLA in complex septal anatomy: a case series.

BACKGROUND: The appropriate treatment strategy for secondary stroke prevention in patients with cryptogenic stroke and patent foramen ovale (PFO) remains challenging. The aim of this study was to describe a case series of patients with PFO and complex septal anatomy who underwent percutaneous correction using a FIGULLA (Occlutech) septal occluder (FSO). PATIENTS: Ten consecutive patients (6 females, 4 males, mean age 41.6 ± 16.0 years, range 17-52 years; group 1) with cryptogenetic stroke and/or transient cerebral ischemia and complex septal anatomy, as defined by intraprocedural transesophageal echocardiogram (TEE) were compared with a group of 25 patients (10 females, 15 males, mean age 43.7 ± 12.3 years; group 2) with usual tunnel-like PFO anatomy in whom PFO was closed by an Amplatzer septal occluder (ASO; AGA). RESULTS: No significant differences were noted between group 1 and group 2 for immediate success rate, residual intraprosthetic shunt at the end of the procedure, discharge, 1, 6 and 12 months follow up, number of attempts, procedure time, fluoroscopy time, or cardiac complication (atrial arrhythmias, device embolism). The only significant difference was shown for delivery sheath size (11 ± 2 versus 9 ± 1 F) and incidence of local hematoma (30% versus 12%) between group 1 and group 2, without any clinical consequence (need of transfusion) or increase in length of stay. CONCLUSION: FSO shows high performance in patients with PFO and complex septal anatomy when compared with patients with PFO and uncomplicated atrial anatomy treated by ASO. Its favorable behavior is probably related to fabric features such as the total amount of metal and the presence of titanium.