Muscular Ridge Research Articles

Anatomy of the heart of the leatherback turtle.

Non‐crocodylian reptiles have hearts with a single ventricle, which is partially separated by a muscular ridge that provides some separation of blood flows. An exceptional situation exists in monitor lizards and pythons, where the ventricular left side generates a much higher systolic blood pressure than the right side, thus resembling mammals and birds. This functional division of the ventricle depends on a large muscular ridge and may relate to high metabolic demand. The large leatherback turtle (<1000 kg), with its extensive migrations and elevated body temperatures, may have similar adaptations. We report on the anatomy of the hearts of two leatherback turtles. One stranded in Ballum, Denmark in 2020, and was examined in detail, supplemented by observations and photos of an additional stranding specimen from Canada. The external morphology of the leatherback heart resembles that of other turtles, but it is large. We made morphometric measurements of the Ballum heart and created an interactive 3D model using high‐resolution MRI. The volume of the ventricle was 950 ml, from a turtle of 300 kg, which is proportionally almost twice as large as in other reptiles. The Ballum heart was compared to MRI scans of the hearts of a tortoise, a python, and a monitor lizard. Internally, the leatherback heart is typical of non‐crocodylian reptiles and did not contain the well‐developed septation found in pythons and monitor lizards. We conclude that if leatherback turtles have exceptional circulation needs, they are sustained with a relatively large but otherwise typical non‐crocodylian reptile heart.

V13-10 DISTAL LEVATOR PLICATION: AN ADJUNCT FOR ANTERIOR PREDOMINANT PELVIC ORGAN PROLAPSE REPAIR

You have accessJournal of UrologyFemale Pelvic Surgery (V13)1 Apr 2020V13-10 DISTAL LEVATOR PLICATION: AN ADJUNCT FOR ANTERIOR PREDOMINANT PELVIC ORGAN PROLAPSE REPAIR Jessica Rueb*, Michele Fascelli, Neil Kocher, Samir Derisavifard, and Howard Goldman Jessica Rueb*Jessica Rueb* More articles by this author , Michele FascelliMichele Fascelli More articles by this author , Neil KocherNeil Kocher More articles by this author , Samir DerisavifardSamir Derisavifard More articles by this author , and Howard GoldmanHoward Goldman More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000000970.010AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Levator myorrhaphy was first described as a constricting technique in 1961 with wide levator ani midline plication to which the vaginal cuff was affixed. This was considered for patients who did not intend to be sexually active and reported low morbidity. Our technique of distal levator plication (DLP) is a reconstruction of the levator ani complex proximal to and at the vaginal introitus. This approach is preferred for minimal posterior prolapse wherein traditional colpocleisis would be difficult. We seek to describe out technique. METHODS: Here we describe DLP in an 85-year-old female status post total abdominal hysterectomy who presented with symptomatic pelvic organ prolapse. Exam demonstrated a stage 3 cystocele and the vaginal cuff was within two centimeters of the hymen. She no longer was interested in sexual activity. After anterior colporrhaphy and apical suspension, DLP is performed. A rectangular area of posterior vaginal epithelium is excised to expose the fibromuscular layer, extending from the hymenal ring to 2-3 cm proximal. The levator ani are plicated with 0-PDS to create a muscular ridge overlying the distal portion of rectum and perineum prior to recreating the perineal body. RESULTS: All compartments are well supported and the end result is a narrowed genital hiatus, accommodating approximately one to two finger breadths. Post-operatively, vaginal packing is removed in the recovery unit, the patient is discharged home on post-operative day (POD) 0, and outpatient voiding trial is performed on POD two. CONCLUSIONS: In our experience, DLP combined with anterior and apical repairs results in a greater than 95% symptomatic resolution. Source of Funding: None © 2020 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 203Issue Supplement 4April 2020Page: e1213-e1213 Advertisement Copyright & Permissions© 2020 by American Urological Association Education and Research, Inc.MetricsAuthor Information Jessica Rueb* More articles by this author Michele Fascelli More articles by this author Neil Kocher More articles by this author Samir Derisavifard More articles by this author Howard Goldman More articles by this author Expand All Advertisement PDF downloadLoading ...

P1500 Reptilian heart in a man

Abstract 40 year old man admitted to hospital due to tachycardia episode. His normal ECG was consistent with RBBB with a QRS duration of 200msec. He had undergone a VSD operation when he was 6. He had a 3/6 systolic murmor . On TTE, there was a VSD patch and a residual tiny VSD with a L-R shunt. The maximum systolic gradient of VSD shunt was measured as 92mmHg .There was also moderate tricuspid regurgitation (TR) with a peak velocity of 5.1m/sec and estimated sPAP of 103mmHg. Considering the measured sPAP and the VSD shunt gradients, his systolic blood pressure (SBP)should approximately be equal to sum of those two ( 103+ 92 = 195mmHg). However his BP was 140/90mmHg.When we examined his heart for a possible explanation for this inconsistency, we noticed a systolic aliasing inside the RV with a maximum velocity of 3.1m/sec and systolic gradient of 38mmHg. However the chamber with lower pressure (P) was the one to which the VSD shunt was directed, and this chamber was in direct continuity with pulmonary artery. So to confirm the P in this chamber we also used pulmonary regurgitation flow and measured a peak diastolic velocity of 3.8m/sec, meaning a mean PAP of 60mmHg .Cardiac catheterization also confirmed a sPAP of 116mmHg and mPAP of 65mmHg. The systolic aortic P was 145mmHg and systolic LV P was 152mmHg. So the unexpectedly high gradient of VSD shunt was still a mystery for us. While searching the literature to explain this , we noticed that the patients’ heart was resembling the reptilian heart model. The reptilian heart has two atria and one ventricle with 3 segments seperated via muscular ridges. In our patients’ heart ,the small chamber with high P in the RV was the cavum venosum, the larger chamber of RV with VSD was the cavum pulmonale, and the left ventricle was the cavum arteriosum. (Fig) The reptilian hearts typically have noncompacted myocardium which was actually the case in our patient. The reptilian hearts also have unique conduction system with no AV node and His bundle, and slow depolarization of ventricle from left to right. When we performed EPS, we found that the patient had no AV node and His bundle. Bringing together all these findings, we conclude that the patient has a reptilian heart with all anatomical, electrical and physiological features. And the answer to the mystery of inconsistent P recordings was hidden in ECG. The RBBB with very long QRS duration causes a delay between contraction of ventricles resulting in a dynamic P gradient between ventricles. We demonstrated this dinamic bidirectional shunt on CW recording when we obtained a more optimal recording of the shunt flow.This case demonstrates us one more evidence of human evolution; arising from single cell and developing to fish, to reptiles and to mammals. The evolution takes place again and again during neonatal life. If there is an embryological arrest, as occured in our patient, we can easily see the clues of this amazing human evolution. Abstract P1500 Figure

P1691 A case of congenital pulmonary stenosis

Abstract Introduction We present an unusual case of sequential right ventricular outflow tract obstruction (RVOTO) caused by pulmonary and subpulmonary stenosis, with formation of aortopulmonary collaterals. Case presentation We report a case of a 47 year old Senegalese man who presented with a three year history of shortness of breath on exertion which worsened over the past week. Cardiovascular examination revealed a parasternal heave, a systolic murmur loudest in the pulmonary area and no evidence of fluid overload. A transthoracic echocardiogram revealed leftward septal deviation during systole due to right ventricular pressure overload, severe right ventricular hypertrophy (RV free wall end-diastolic thickness of 8mm) and normal systolic function (FAC 47%), a dilated right atrium and moderate tricuspid regurgitation with estimated maximum pressures of 112mmHg. On continuous-wave doppler of the right ventricular outflow tract (RVOT), there was a late peaking systolic flow with maximum velocity of 3.8m/s. A cardiac computed tomography (CT) and cardiac magnetic resonance imaging (MRI) was performed which showed sequential stenoses of the RVOT; one at subvalvular level by an infundibular muscular ridge with an area of 0.7 cm2 in mid-systole and one at the level of a dome-shaped pulmonary valve with planimetered valve area of 0.5cm2, severe RV hypertrophy and normal RV ejection fraction. Aortopulmonary collaterals from proximal thoracic descending aorta were seen. The main pulmonary artery was shown to be dilated with no evidence of pulmonary artery branch stenosis. See image: In-plane phase contrast velocity flow mapping of the RVOT using a VENC of 80cm/s, showing aliasing at the level of the pulmonary valve (red arrow) and at the level of the infundibulum (white arrow). Conclusion Congenital pulmonary stenosis (PS) occurs in 8% of congenital heart defects. 80% of pulmonary valve stenosis is typically dome-shaped with commissural fusion whilst the remainder is of the dysplastic type. Congenital PS can be associated with RVOTO at the infundibular level secondary to reactive muscular hypertrophy. In our case, there is a discrete, circumferential muscular ridge at the level of the infundibulum resulting in sequential outflow tract obstruction. PS with intact ventricular septum occurs in conjunction with varying degrees of right ventricular hypertrophy and elevated right ventricular systolic pressures. A dilated pulmonary artery is common in dome-shaped subtype of PS. Survival into adulthood of severe PS is primarily dependent on the adequacy of pulmonary blood flow from systemic-to-pulmonary collateral arteries, which serve as an additive, or the only source of blood supply to the pulmonary arterial vasculature. These collaterals are usually seen in association with cyanotic congenital heart disease such as pulmonary atresia and tetralogy of fallot. Abstract P1691 Figure. Sequential RVOTO

P220 Behcet"s disease with right ventricular aneurysm

Abstract Funding Acknowledgements Nil Introduction Behcet’s disease (BD) is a rare inflammatory disorder, which predominantly impacts people of Mediterranean and East Asian origin. While the aetiology is unknown, the prevailing disorder is vasculitis. Oral, skin and ocular lesions are common: cardiac involvement is rare. Case description A sixty-three year old male with Behcet’s disease (BD) presented for review. On clinical examination, atrial fibrillation, prominent V waves, mild pedal oedema and a ‘to and fro’ murmur were noted. Marked elevation of right ventricular (RV) end diastolic pressure was measured by cardiac catheter. Echocardiography and magnetic resonance imaging revealed significant RV abnormalities. The mid and apical RV regions were heavily trabeculated, and an anterior aneurysm was identified (see 2D image in abstract picture). A prominent horizontal muscular ridge in the basal RV was noted, and the RV outflow tract was narrowed. While the tricuspid valve was not apically displaced, leaflet coaptation was absent with subsequent severe tricuspid regurgitation into a grossly enlarged right atrium (see colour image in abstract picture). Management included diuretics and continuing immunosuppressives. Discussion BD is a rare (chronic) inflammatory disorder, which mainly affects people of Mediterranean and East Asian origin, and is often first diagnosed (in the third or fourth decades of life) following recurrent oral ulcerations, skin and ocular lesions. With BD, the prevailing disorder is vasculitis. Blood vessels of all sizes, both arteries and veins, are impacted: true or false aneurysms can occur. BD rarely affects the heart. If there is cardiac involvement, pericarditis is the most common lesion - others include myocarditis, mitral valve prolapse, intra-cardiac thrombus and myocardial infarction. We present a rare (and possibly unique) cardiac manifestation of BD, anterior RV aneurysm. Conclusion In this case report we present a rare cardiac manifestation of BD, anterior RV aneurysm. Abstract P220 Figure. Echocardiography Images

Identification of the building blocks of ventricular septation in monitor lizards (Varanidae).

Among lizards, only monitor lizards (Varanidae) have a functionally divided cardiac ventricle. The division results from the combined function of three partial septa, which may be homologous to the ventricular septum of mammals and archosaurs. We show in developing monitors that two septa, the 'muscular ridge' and 'bulbuslamelle', express the evolutionarily conserved transcription factors Tbx5, Irx1 and Irx2, orthologues of which mark the mammalian ventricular septum. Compaction of embryonic trabeculae contributes to the formation of these septa. The septa are positioned, however, to the right of the atrioventricular junction and they do not participate in the separation of incoming atrial blood streams. That separation is accomplished by the 'vertical septum', which expresses Tbx3 and Tbx5 and orchestrates the formation of the electrical conduction axis embedded in the ventricular septum. These expression patterns are more pronounced in monitors than in other lizards, and are associated with a deep electrical activation near the vertical septum, in contrast to the primitive base-to-apex activation of other lizards. We conclude that evolutionarily conserved transcriptional programmes may underlie the formation of the ventricular septa of monitors.

Use of Intracardiac Echocardiography in Interventional Cardiology: Working With the Anatomy Rather Than Fighting It.

The indications for catheter-based structural and electrophysiological procedures have recently expanded to more complex scenarios, in which an accurate definition of the variable individual cardiac anatomy is key to obtain optimal results. Intracardiac echocardiography (ICE) is a unique imaging modality able to provide high-resolution real-time visualization of cardiac structures, continuous monitoring of catheter location within the heart, and early recognition of procedural complications, such as pericardial effusion or thrombus formation. Additional benefits are excellent patient tolerance, reduction of fluoroscopy time, and lack of need for general anesthesia or a second operator. For these reasons, ICE has largely replaced transesophageal echocardiography as ideal imaging modality for guiding certain procedures, such as atrial septal defect closure and catheter ablation of cardiac arrhythmias, and has an emerging role in others, including mitral valvuloplasty, transcatheter aortic valve replacement, and left atrial appendage closure. In electrophysiology procedures, ICE allows integration of real-time images with electroanatomic maps; it has a role in assessment of arrhythmogenic substrate, and it is particularly useful for mapping structures that are not visualized by fluoroscopy, such as the interatrial or interventricular septum, papillary muscles, and intracavitary muscular ridges. Most recently, a three-dimensional (3D) volumetric ICE system has also been developed, with potential for greater anatomic information and a promising role in structural interventions. In this state-of-the-art review, we provide guidance on how to conduct a comprehensive ICE survey and summarize the main applications of ICE in a variety of structural and electrophysiology procedures.

In situ cardiac perfusion reveals interspecific variation of intraventricular flow separation in reptiles.

The ventricles of non-crocodilian reptiles are incompletely divided and provide an opportunity for mixing of oxygen-poor blood and oxygen-rich blood (intracardiac shunting). However, both cardiac morphology and in vivo shunting patterns exhibit considerable interspecific variation within reptiles. In the present study, we develop an in situ double-perfused heart approach to characterise the propensity and capacity for shunting in five reptile species: the turtle Trachemys scripta, the rock python Python sebae, the yellow anaconda Eunectes notaeus, the varanid lizard Varanus exanthematicus and the bearded dragon Pogona vitticeps To simulate changes in vascular bed resistance, pulmonary and systemic afterloads were independently manipulated and changes in blood flow distribution amongst the central outflow tracts were monitored. As previously demonstrated in Burmese pythons, rock pythons and varanid lizards exhibited pronounced intraventricular flow separation. As pulmonary or systemic afterload was raised, flow in the respective circulation decreased. However, flow in the other circulation, where afterload was constant, remained stable. This correlates with the convergent evolution of intraventricular pressure separation and the large intraventricular muscular ridge, which compartmentalises the ventricle, in these species. Conversely, in the three other species, the pulmonary and systemic flows were strongly mutually dependent, such that the decrease in pulmonary flow in response to elevated pulmonary afterload resulted in redistribution of perfusate to the systemic circuit (and vice versa). Thus, in these species, the muscular ridge appeared labile and blood could readily transverse the intraventricular cava. We conclude that relatively minor structural differences between non-crocodilian reptiles result in the fundamental changes in cardiac function. Further, our study emphasises that functionally similar intracardiac flow separation evolved independently in lizards (varanids) and snakes (pythons) from an ancestor endowed with the capacity for large intracardiac shunts.

Congenitally unguarded tricuspid valve orifice with right ventricular apical isolation in an adult

Congenitally unguarded tricuspid valve (TV) orifice, a variant of TV dysplasia, is a rare malformation with protean manifestations. This report describes a symptomatic adult male with gross right heart failure and atrial fibrillation, who was found to have an unguarded TV orifice with isolation of the trabecular apical cavity of the right ventricle (RV) and muscular ridges separating outflow tract (forme-fruste of the double-chambered RV). The right ventricular outflow tract remained patent.

Ventricular Noncompaction and Associated Cardiac Anomalies

An 80-year-old woman was referred for transcatheter aortic valve implantation for correction of aortic stenosis. An echocardiogram at the author’s institution revealed severe hypertrophy of the left ventricle with deep recesses into the myocardium and hypokinesis involving the left ventricular apex. In addition, there was subaortic stenosis secondary to a muscular ridge. The aortic valve was only mildly stenotic. In this Cardiology Grand Rounds, the authors present a rare case of ventricular noncompaction and review the literature on this subject and its association with other cardiac abnormalities.

The heart of the South American rattlesnake, Crotalus durissus

Most anatomical and physiological studies of the sauropsid heart have focused on species with extraordinary physiologies, and detailed anatomical descriptions of hearts from sauropsids with more common physiologies are therefore warranted. Here, we present a comprehensive study of the cardiac anatomy of the South American rattlesnake (Crotalus durissus). The cardiovascular physiology of this species has been investigated in a number of studies, whereas only a few cursory studies exist on the cardiac anatomy of viperid snakes. The heart of C. durissus is typically squamate in many regards. Both atria are thin-walled sacs, and the right atrium is the most voluminous. The single ventricle contains three major septa; the vertical septum, the muscular ridge (MR), and the bulbuslamelle. These partially divide the ventricle into three chambers; the systemic and left-sided cavum arteriosum (CA), the pulmonary and right-sided cavum pulmonale, and the medial cavum venosum (CV). The MR is the most developed septum, and several additional and minor septa are found within the CA and CV. An extraordinary thin cortical layer encloses the ventricle, and it is irrigated by a remarkably rich arborization of coronary arteries. Previous studies show high degrees of blood flow separation in the Crotalus heart, and this can only be explained by the coordinated actions of the septa and the prominent atrioventricular valves.

How the python heart separates pulmonary and systemic blood pressures and blood flows

The multiple convergent evolution of high systemic blood pressure among terrestrial vertebrates has always been accompanied by lowered pulmonary pressure. In mammals, birds and crocodilians, this cardiac separation of pressures relies on the complete division of the right and left ventricles by a complete ventricular septum. However, the anatomy of the ventricle of most reptiles does not allow for complete anatomical division, but the hearts of pythons and varanid lizards can produce high systemic blood pressure while keeping the pulmonary blood pressure low. It is also known that these two groups of reptiles are characterised by low magnitudes of cardiac shunts. Little, however, is known about the mechanisms that allow for this pressure separation. Here we provide a description of cardiac structures and intracardiac events that have been revealed by ultrasonic measurements and angioscopy. Echocardiography revealed that the atrioventricular valves descend deep into the ventricle during ventricular filling and thereby greatly reduce the communication between the systemic (cavum arteriosum) and pulmonary (cavum pulmonale) ventricular chambers during diastole. Angioscopy and echocardiography showed how the two incomplete septa, the muscular ridge and the bulbuslamelle - ventricular structures common to all squamates - contract against each other in systole and provide functional division of the anatomically subdivided ventricle. Washout shunts are inevitable in the subdivided snake ventricle, but we show that the site of shunting, the cavum venosum, is very small throughout the cardiac cycle. It is concluded that the python ventricle is incapable of the pronounced and variable shunts of other snakes, because of its architecture and valvular mechanics.

Anatomy of the python heart

The hearts of all snakes and lizards consist of two atria and a single incompletely divided ventricle. In general, the squamate ventricle is subdivided into three chambers: cavum arteriosum (left), cavum venosum (medial) and cavum pulmonale (right). Although a similar division also applies to the heart of pythons, this family of snakes is unique amongst snakes in having intracardiac pressure separation. Here we provide a detailed anatomical description of the cardiac structures that confer this functional division. We measured the masses and volumes of the ventricular chambers, and we describe the gross morphology based on dissections of the heart from 13 ball pythons (Python regius) and one Burmese python (P. molurus). The cavum venosum is much reduced in pythons and constitutes approximately 10% of the cavum arteriosum. We suggest that shunts will always be less than 20%, while other studies conclude up to 50%. The high-pressure cavum arteriosum accounted for approximately 75% of the total ventricular mass, and was twice as dense as the low-pressure cavum pulmonale. The reptile ventricle has a core of spongious myocardium, but the three ventricular septa that separate the pulmonary and systemic chambers--the muscular ridge, the bulbuslamelle and the vertical septum--all had layers of compact myocardium. Pythons, however, have unique pads of connective tissue on the site of pressure separation. Because the hearts of varanid lizards, which also are endowed with pressure separation, share many of these morphological specializations, we propose that intraventricular compact myocardium is an indicator of high-pressure systems and possibly pressure separation.

Hemodynamic Consequences of Cardiac Malformations in Two Juvenile Ball Pythons (Python regius)

Two cases of bifid ventricles and cardiac malformations in juvenile ball python (Python regius) were investigated by blood pressure measurements and macro- and microscopic sectioning. A study of a normal ball python was included for reference. In both cases, all cardiac chambers were enlarged and abnormally shaped. Internal assessment of the ventricles revealed a pronounced defect of the muscular ridge, which normally is responsible for separating the systemic and pulmonary circuits. Consistent with the small muscular ridge, systolic pressures were identical in the pulmonary and systemic arteries, but, the snakes, nevertheless, lived to reach body weights severalfold of their hatchling weight.

Laparoscopic Strassman’s metroplasty for bicornuate uterus

The authors report the case of a 28-year-old nulliparous woman with a bicornuate uterus and one previous second trimester pregnancy loss, in whom investigations for other probable causes of abortion like genetic, infective, hormonal, and immunological were negative. A laparoscopic metroplasty was performed by Strassman’s method. Second-look hysteroscopy and laparoscopy, which was performed 7 months later, revealed a single uniform cavity with a median muscular ridge, which resembled an arcuate uterus. Pelvic adhesions were noted between the small bowel, omentum, and posterior wall of the uterus, along with pelvic endometriosis and a chocolate cyst of the left ovary. Adhesiolysis, cyst excision, and fulgration of endometriotic deposits were carried out, which were followed by the application of an adhesion barrier.

Functional morphology and patterns of blood flow in the heart of Python regius

Brightness-modulated ultrasonography, continuous-wave Doppler, and pulsed-wave Doppler-echocardiography were used to analyze the functional morphology of the undisturbed heart of ball pythons. In particular, the action of the muscular ridge and the atrio-ventricular valves are key features to understand how patterns of blood flow emerge from structures directing blood into the various chambers of the heart. A step-by-step image analysis of echocardiographs shows that during ventricular diastole, the atrio-ventricular valves block the interventricular canals so that blood from the right atrium first fills the cavum venosum, and blood from the left atrium fills the cavum arteriosum. During diastole, blood from the cavum venosum crosses the muscular ridge into the cavum pulmonale. During middle to late systole the muscular ridge closes, thus prohibiting further blood flow into the cavum pulmonale. At the same time, the atrio-ventricular valves open the interventricular canal and allow blood from the cavum arteriosum to flow into the cavum venosum. In the late phase of ventricular systole, all blood from the cavum pulmonale is pressed into the pulmonary trunk; all blood from the cavum venosum is pressed into both aortas. Quantitative measures of blood flow volume showed that resting snakes bypass the pulmonary circulation and shunt about twice the blood volume into the systemic circulation as into the pulmonary circulation. When digesting, the oxygen demand of snakes increased tremendously. This is associated with shunting more blood into the pulmonary circulation. The results of this study allow the presentation of a detailed functional model of the python heart. They are also the basis for a functional hypothesis of how shunting is achieved. Further, it was shown that shunting is an active regulation process in response to changing demands of the organism (here, oxygen demand). Finally, the results of this study support earlier reports about a dual pressure circulation in Python regius.

Morphological characters and classification of the subclass Monilifera (Pogonophora) and the problem of evolution of the bridle in pogonophorans

This paper presents the results of the revision of the subclass Monilifera (Pogonophora) based on an analysis of all currently known morphological features. The most important diagnostic characters of Monilifera are the presence of two tentacles without pinnules, a neurotroch on the forepart, a fragmented bridle, a transparent rigid tube, the lack of postannular region, and spermatophores. A few characters are newly proposed for the systematics of Monilifera: the length of tentacles, cephalic lobe, and forepart relative to the forepart diameter, average forepart diameter, paired coelom I, the presence of multicellular glands in the prefrenular region of first segment, the lack of muscular ridges of girdles, unfolded and nonconcave opisthosomal growth zone, teethed opisthosomal setae being arranged in four transverse rows or in a circle on each setigerous segment. The modified and expanded differential diagnoses of subclass Monilifera, order Sclerolinida, family Sclerolinidae, and genus Sclerolinum are given. Archeolinum gen. n. is erected to accommodate all moniliferan species, except for Sclerolinum sibogae Southward, 1961, on the basis of bridle and tube structure, as well as the most important morphometric parameters of forepart. All data on the morphology and evolution of the bridle as one of the most peculiar organs of pogonophorans are systematized. A complete series of transformations of the bridle structure is proposed: from plesiomorphic simple cuticular plaques scattered on the forepart dorsal surface to regular plaques with a thickened edge, ridge, and rodlike bodies. The merging of individual cuticular plaques and the reduction of their membranes resulted in the formation of a fused bridle. However, the traces of rodlike bodies and their derivates (the so-called blocks) can be found in many apomorphic bridles. Finally, total reduction of all elements of the initial cuticular plaque, except the thickened edge, led to the formation of a homogenous bridle, which is characteristic of most pogonophorans.

Double chambered ventricles: A retrospective clinicopathological study

Introduction Double chambered ventricle is a rare congenital cardiac anomaly, where the ventricular chamber is wholly or partially partitioned usually by abnormal muscular ridges. Double chambered right ventricle (DCRV) is more common than double chambered left ventricle (DCLV).

Ventricular haemodynamics inPython molurus: separation of pulmonary and systemic pressures

Vascular pressure separation by virtue of a two-chambered ventricle evolved independently in mammals and birds from a reptilian ancestor with a single ventricle, and allowed for high systemic perfusion pressure while protecting the lungs from oedema. Within non-crocodilian reptiles, ventricular pressure separation has only been observed in varanid lizards and has been regarded as a unique adaptation to an active predatory life style and high metabolic rate. The systemic and pulmonary sides of the ventricle in Python molurus are well separated by the muscular ridge, and a previous study using in situ perfusion of the heart revealed a remarkable flow separation and showed that the systemic side can sustain higher output pressures than the pulmonary side. Here we extend these observations by showing that systemic blood pressure P(sys) exceeded pulmonary pressure P(pul) almost seven times (75.7+/-4.2 versus 11.6+/-1.1 cm H(2)O). The large pressure difference between the systemic and pulmonary circulation persisted when P(sys) was altered by infusion of sodium nitroprusside or phenylephrine. Intraventricular pressures, measured in anaesthetised snakes, showed an overlap in the pressure profile between the pulmonary side of the ventricle (cavum pulmonale) and the pulmonary artery, while the higher pressure in the systemic side of the ventricle (cavum arteriosum) overlapped with the pressure in the right aortic arch. This verifies that the pressure differences originate within the ventricle, indicating that the large muscular ridge separates the ventricle during cardiac contraction.

Intracardiac flow separation in an in situ perfused heart from Burmese python Python molurus.

The heart of non-crocodilian reptiles has two separate atria that receive blood from the systemic and pulmonary circulations. The ventricle is not fully divided, but is compartmentalised into two chambers (cavum dorsale and cavum pulmonale) by a muscular ridge that runs from the apex to the base of the ventricle. The muscular ridge is small in turtles, but is well developed in varanid lizards and many species of snakes. These anatomical differences correlate with an effective blood flow separation in varanid lizards, whereas turtles can exhibit very large cardiac shunts. Very little is known about the cardiac shunt patterns in other groups of reptiles. Here we characterise cardiac performance and flow dynamics in the Burmese python (Python molurus) using an in situ perfused heart preparation. The pericardium remained intact and the two atria were perfused separately (Ringer solution), and the two systemic and the pulmonary outflows were independently cannulated. Right and left atrial filling pressures and ventricular outflow pressures of the pulmonary and systemic vessels could be manipulated independently, permitting the establishment of large experimental intraventricular pressure gradients across the muscular ridge. The maximal power output generated by the systemic side of the ventricle exceeded the maximal power output that was generated by the cavum pulmonale that perfuse the pulmonary circulation. Furthermore, systemic flow could be generated against a higher outflow pressure than pulmonary flow. Perfusate entering the right atrium was preferentially distributed into the pulmonary circulation, whereas perfusate into the left atrium was distributed to the systemic circulation. Our study indicates that the well-developed muscular ridge can separate the cavum systemic and pulmonary sides of the heart to prevent mixing of systemic and pulmonary flows. Therefore, the heart of Python appears to exhibit a large degree of ventricular flow separation as previously described for varanid lizards. We speculate that the ventricular separation has evolved in response to the need of maintaining high oxygen delivery while protecting the pulmonary circulation from oedema as result of high vascular pressures.