Vascular Trunk Research Articles

Avalvulia of both lower limb veins

A 48 year old female had enrolled herself in a project on post prophylaxis of deep vein thrombosis. The project involved administration of intravenous antithromboltic drug in patients undergoing major abdominal surgery lasting more than 45 min under general anesthesia. She had been operated for carcinoma ascending colon. She had no complaints of lower limb pain, ulcer, claudication or swelling. However on examination there were prominent reticular veins over both thighs. On the eighth postoperative day conventional venography of both lower limbs was done after obtaining informed consent and ensuring a normal renal function test. Nonionic contrast (Ultravist 300, Schering AG, Berlin, Germany) was injected in each lower limb in the proximal part of the great saphenous vein just below the ankle joint after applying a tourniquet just above the ankle joint. Serial radiographs of different parts in various views were taken on a computerized radiography system (Kodak Direct View Elite CR System). During analysis of the venogram we found that the deep venous systems were normal in course and caliber. No evidence of deep vein thrombosis was present. Superficial venous systems were opacified simultaneously despite placement of tourniquet at appropriate sites with adequate applied pressure. There was absence of venous valves in the perforators and deep and superficial venous systems in both lower limbs (Fig. 2a and b). A color Doppler study was done (GE Logic P5) which showed reflux into the superficial venous system during mild Valsalva maneuver. The perforators were incompetent and mildly dilated with lack of venous valves in superficial and deep venous systems in both lower limbs (Fig. 3a and b). The other Doppler indices including velocity, color filling and wave form pattern were normal in both lower limbs. The venous systems of the lower limb are provided with pocket –shaped formations called valves. These are generally bicuspid, rarely tricuspid extraversions of endothelium and tunica media with muscle bundles connected at the valve base to provide support to the venous walls so that they can withstand gravitational pressure of the venous blood column. The numbers of valves in superficial and deep systems decrease progressively from distal to proximal regions and they are rarely seen in the caval vein (Fig. 1a and b). Common congenital venous anomalies like aplasia/hypoplasia and avalvulia are the result of the developmental arrest of later stages of vascular trunk formation during early fetal growth. Embryologically these lesions are also known as “post-truncal fetal lesions”. Truncal lesions are further subdivided into obstruction, aplasia or hypoplasia [1–8]. Avalvulia or absence of valves is severe form of hypoplasia that produces venous reflux. Avalvulia is a common finding in KlippelTrenaunay syndrome. There is no age or sex predilection. Diagnosis is made by one or more of the following methods: color doppler imaging, plethysmography, contrast enhanced computed tomography, magnetic resonance venography and conventional or digital venography. Knowledge of integrity of deep venous system is mandatory because of the many venous interventional M. Kumar (*) : R. Singh Department of Radiodiagnosis, King George’s Medical University Lucknow, Uttarpradesh, India PIN-226003 e-mail: docmdeo@gmail.com

Structure and Clinical Significance of Central Optic Disc Pits

To assess the structure of central optic disc pits (ODPs) using enhanced-depth imaging optical coherence tomography (EDI OCT) and to ascertain their clinical significance. Prospective, cross-sectional study. Patients with an ophthalmoscopically visible central ODP in either eye, irrespective of accompanying ocular disease, were enrolled from the neuro-ophthalmology and glaucoma referral practices. Each subject with a central ODP was matched with 2 healthy subjects with normal-appearing optic disc within 5 years of age. Each participant received a complete ophthalmologic examination including standard automated perimetry, retinal nerve fiber layer (RNFL) thickness measurement by OCT, and serial horizontal and vertical cross-sectional EDI OCT of the optic nerve head. Structure of the lamina cribrosa (LC) in relation to the central ODP in EDI OCT images. Eighteen eyes (13 subjects) with a central ODP and 52 healthy eyes (26 controls) were included. Four eyes (2 subjects) with a central ODP were otherwise normal with intact macula, neuroretinal rim, RNFL, and visual field. Fourteen eyes (11 subjects) with a central ODP had glaucoma with glaucomatous neuroretinal rim thinning, RNFL loss, and corresponding visual field defect. No eye had associated maculopathy. On EDI OCT, the central ODP corresponded with a full-thickness defect in the LC center with no serous retinal detachment or herniation of neural tissue through the LC defect. Central ODPs were separated from (type 1) or merged with (type 2) the LC opening for the central retinal vascular trunk. In control eyes, no LC defect was detected. Central ODPs are full-thickness LC defects unassociated with maculopathy and different from glaucomatous acquired pits of the optic nerve, which represent focal laminar defect adjacent to the disc edge.

CT angiographic evaluation of perforators in the lower limb and their reconstructive implication

Background:The perforator flaps evolved on the knowledge of the vascular tree from the main vascular trunk up to the subdermal plexus. Therefore, we thought that it's necessary to map the whole vascular arcade by CT angiography. The aim of this study is to evaluate the perforators and the whole vascular tree of the lower limb by peripheral CT angiography with 3D reconstruction and intraoperative evaluation. This study helps in designing flaps of different constituents based on the selected perforators.Materials and Methods:Twenty patients having lower limb defects were selected. CT angiography was done using a non-ionic iodinated contrast media injected through the antecubital vein. The lower limbs were imaged using volume rendering CT scan machine. Three dimensional reconstructions were made. The whole arterial tree, along with the perforators, were mapped. Findings of the audio-Doppler were correlated with the CT angiographic observations. Further these evaluations were confirmed by intraoperative findings.Results:The three dimensional CT angiographic reconstruction with bone and soft tissue provided advanced knowledge of this vascular network. It delineated the main vessel, the perforators, their caliber, distance from fixed bony landmarks and course up to the subdermal plexus. These findings were confirmed during dissection of the proposed flap. The perforators were mainly musculocutaneous in the proximal leg and septocutaneous distally.Conclusions:The vascular details visualized by this technique made advancement over the existing methods namely color Doppler, audio Doppler, two dimensional angiography etc. It improved the understanding of perforator flaps and their successful clinical application.

Juvenile Angiofibroma: The “Anchorage” Concept

Objective: To present the Anchorage Concept, a set of characteristics shown by juvenile nasopharyngeal angiofibroma (JNA) that hinder the surgical resection and contribute to intraoperative complications and incomplete excisions. Method: Case series consisting of 46 JNAs in the past 10 years (2001-2011) and including tumors I to IIIb in Radowski staging classification. Surgical technique varied according to tumor stage and included exclusive endoscopic surgery, external access and combined, with or without preoperative embolization. Results: Multiplicity of vascular pedicles: The maxillary artery, JNA’s principal irrigation source, commonly presents as an extension of the lesion, laterally positioned. This characteristic makes vascular clipping difficult and demands a careful surgical dissection next to the external carotid vascular trunk. Besides its main vascular trunk, JNA has many other vascular pedicles which become an anchoring factor and provoke intraoperative bleeding. Vector and growth angles: During its growth, JNA may dispose vectors that form angles in relation to nasal cavity. Sometimes, these angles are 90° shaped. From its origin at the upper margin of the sphenopalatine foramen, JNA grows forward and backward into the nasal cavity and maxillary sinus, upward into the sphenoid, laterally toward the pterygopalatine fossa, and inferiorly toward the infratemporal fossa, via the pterygomaxillary fissure. Conclusion: The Anchorage Concept must be taken into account in the management of JNA. Knowledge of these points is of great value to facilitate the removal of the tumor, which persists being a surgical challenge in most cases.

Distally based sural fasciomusculocutaneous flap for treatment of wounds of the distal third of the leg and ankle with exposed internal hardware

Soft tissue reconstruction of the distal third of the lower limb with exposure of the internal hardware is a challenging problem with several potential complications, such as exposure of the fracture line, fracture instability and bacterial contamination. The treatment of these lesions usually consists of substitution of the internal hardware with external fixation devices and further flap coverage. We propose a different reconstructive approach, characterized by harvesting a sural fasciomusculocutaneous flap on the exposed internal hardware once a sterile ground has been obtained. Four patients were retrospectively analyzed. Soft tissue reconstruction was achieved in all cases. In one case hardware removal was necessary for complete healing. The sural fasciomusculocutaneous flap is a safe alternative to other pedicled and free flaps. Moreover, it allows direct coverage of internal fixators, thus completing the reconstruction in less time. This flap fits best to the morphology of the wound and internal hardware, leaving the main vascular trunk of the leg intact and at the same time providing a reliable vascular supply.

A Chimeric Flap Model in Dogs

Prelamination is sometimes required for reconstruction of specialized organs. The purpose of this study was to create a chimeric flap model in dogs for prelamination. The anatomy of the deep and superficial caudal epigastric vessels, which supply the rectus abdominis muscle and superficial ventral fascia, respectively, were measured in 14 dogs. Their lengths were ~30 mm with the arteries averaging 1.4 mm and veins, 2.5 mm in diameter. These vessels shared a 10-mm-long common trunk with the artery averaging 2 mm and the vein, 3.2 mm in diameter. Chimeric flaps were successfully raised in six dogs based on the common vascular trunk, and they remained well perfused 3 weeks after prelamination. The perfusion territory of the abdominal skin measured 25 cm long and 10 cm wide with methylene blue injection. This study suggests that the caudal epigastric system can be a suitable chimeric flap model in dogs.

A mini pig model for visualization of perforator flap by using angiography and MIMICS

Research performed using animal models has assisted in the understanding of flap anatomy and physiology. Pigs' vasculature in the skin is anatomically and physiologically similar to human, making it an ideal model for research. Until now, most vascular imaging studies are of two-dimensions. The aim of this study is to provide a three-dimensional (3D) model that reveals detailed architecture of the vascular network of the porcine, for accurate quantitative assessment. Five Guangxi Bama minipigs were anaesthetized intramuscularly and underwent whole body lead oxide-gelatin injection. Spiral computed tomography scanning was performed on the subjects and three-dimensional reconstructions were made. Another minipig was used, and underwent Cardiografin injection. 3D-reconstruction was executed in vivo. All subjects were then dissected by layers to document the individual perforators. Angiography using perfusion with lead oxide-gelatine mixture has the advantage of illustrating distinctively the vessels and their perforating branches. However, it is incapable of displaying other tissues structures. Angiography through perfusion with Cardiografin in vivo has the advantage of demonstrating the relationship between arteries and bones. Yet it could only display coarsely the vascular trunk, and is incapable of displaying the vascular network. By combining these two methods, the 3D structure, source, course, and territories of the arteries were presented distinctively. 3D modeling in combination with traditional sectional imaging of the pig model enables blood vessels to be displayed more dynamically with greater realism. The procedure described could be useful for future flap research, by offering a better visualization of the vascular structure of the skin flap, allowing for better anatomical understanding.

Activation of Bone Marrow-Derived Microglia Promotes Photoreceptor Survival in Inherited Retinal Degeneration

The role of microglia in neurodegeneration is controversial, although microglial activation in the retina has been shown to provide an early response against infection, injury, ischemia, and degeneration. Here we show that endogenous bone marrow (BM)-derived microglia play a protective role in vascular and neural degeneration in the retinitis pigmentosa model of inherited retinal degeneration. BM-derived cells were recruited to the degenerating retina where they differentiated into microglia and subsequently localized to the degenerating vessels and neurons. Inhibition of stromal-derived factor-1 in the retina reduced the number of BM-derived microglia and accelerated the rate of neurovascular degeneration. Systemic depletion of myeloid progenitors also accelerated the degenerative process. Conversely, activation of BM-derived myeloid progenitors by systemic administration of both granulocyte colony-stimulating factor and erythropoietin resulted in the deceleration of retinal degeneration and the promotion of cone cell survival. These data indicate that BM-derived microglia may play a protective role in retinitis pigmentosa. Functional activation of BM-derived myeloid progenitors by cytokine therapy may provide a novel strategy for the treatment of inherited retinal degeneration and other neurodegenerative diseases, regardless of the underlying genetic defect.

Vascular Access in Children: The Importance of Microsurgery for Creation of Autologous Arteriovenous Fistulae

Microsurgery gives much better immediate and long term results than classical surgery for the creation of direct arteriovenous fistulae, the best chronic access to blood in children.

Red Wine Prevents Brain Oxidative Stress and Nephropathy in Streptozotocin-induced Diabetic Rats

We have studied the effects of red wine on brain oxidative stress and nephropathy in streptozotocin (STZ)-induced diabetic rats. Diabetes was induced in Wistar rats with a single intraperitonally injection of STZ (50 mg/kg). Two weeks before and four weeks after injection, red wine was given orally in both normal and diabetic rats. Blood samples were taken from the neck vascular trunk in order to determine the glucose, triglycerides, total cholesterol, HDL-cholesterol (HDL-c), atherogenic index (AI), total protein, blood urea nitrogen (BUN), creatinine, insulin, lipid peroxidation products, reduced glutathione (GSH) and superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities. As well, we estimated the lipid peroxidtion, GSH and SOD, GSH-Px and catalase activities in brain and renal homogenates, and the excretion of albumin, proteins and glucose in urine over 24 h period. The administration of STZ caused significant increases in levels of glycosuria, proteinuria, albuminuria, glycemia, total cholesterol and AI, as well as in lipid peroxidation products in the brain, plasma and kidney, whereas it decreased the GSH content and SOD, GSH-Px and catalase activities. Treatment with red wine significantly prevented the changes induced by STZ. These data suggested that red wine has a protective effect against brain oxidative stress, diabetic nephropathy and diabetes induced by STZ, as well as it protects against hypercholesterolemia and atherogenic risk.

Pulmonary Artery Rupture After Attempted Removal of a Pulmonary Artery Catheter

Pulmonary Artery Rupture After Attempted Removal of a Pulmonary Artery Catheter

Toracoscopia em eqüinos: técnica e emprego como método de avaliação da cavidade pleural

Toracoscopia é o método de visibilização da cavidade torácica através de endoscópio rígido ou flexível, indicado como exame auxiliar para diagnóstico das diversas afecções do tórax. Pode ser realizada com o animal sob anestesia geral ou em posição quadrupedal através de anestesia local associada ou não a sedativos. Neste trabalho, foram utilizados seis eqüinos hígidos, que foram submetidos a toracoscopia, em posição quadrupedal, nos dois hemitórax, com intervalo de 15 dias entre cada procedimento. Durante o exame, pôde-se observar as diversas estruturas da cavidade torácica, tais como: músculo diafragma (porção muscular e tendínea), hiato esofágico, mediastino, aorta, troncos dorsal e ventral do nervo vago, ducto torácico, veia ázigos, veias intercostais, músculos intercostais, costelas, tronco nervoso simpático, tronco vascular toracocervical, traquéia, pulmão (lobo cranial e caudal), esôfago, pericárdio, veia cava caudal, nervo frênico e linfonodos aórticos. Discretas alterações foram observadas ao exame físico, laboratorial e ultra-sonográfico no período pós-operatório, sem que trouxessem prejuízos ao desenvolvimento do experimento e recuperação do animal. A toracoscopia mostrou ser exame de auxílio importante, pela facilidade, rapidez de execução, ampla visibilização da cavidade pleural e trauma mínimo ao paciente.

Toracoscopia em eqüinos: estudo comparativo entre duas técnicas de abordagem

A toracoscopia tem sido cada vez mais indicada como exame auxiliar para diagnóstico das diversas afecções do tórax. Com o objetivo de comparar duas técnicas de abordagem para inspeção da cavidade pleural, foram utilizados 16 animais hígidos, que foram submetidos à toracoscopia, dos quais dez sob anestesia geral com intubação orobronquial seletiva e seis em posição quadrupedal sob sedação associada à anestesia local. Foram abordados os hemitórax direito e esquerdo, com intervalo de 15 dias entre cada procedimento. Durante a abordagem, pôde-se observar as diversas estruturas da cavidade torácica, a saber: músculo diafragma (porção muscular e tendínea), hiato esofágico, mediastino, artéria aorta, troncos dorsal e ventral do nervo vago, ducto torácico, veia ázigos, veias intercostais, músculos intercostais, costelas, tronco nervoso simpático, tronco vascular toracocervical, traquéia, pulmão (lobo cranial e caudal), esôfago, pericárdio, veia cava caudal, nervo frênico, linfonodos aórticos. A realização do exame toracoscópico com os animais sedados e mantidos em posição quadrupedal possibilitou a identificação de um maior número de estruturas. A toracoscopia mostrou ser exame de grande auxilio, pela facilidade e rapidez de execução e ampla inspeção da cavidade pleural, mas a escolha de posicionamento do animal irá depender do órgão ou estrutura a ser preferencialmente abordada. Nos casos em que se optar pelo decúbito, há que se considerar o emprego da ventilação mecânica com intubação orobronquial seletiva.

The lateral forearm flap as a modification of the lateral arm flap: vascular anatomy and clinical implications.

The forearm extension of the lateral arm flap was introduced on the basis of the vascular territory of the posterior radial collateral artery extending beyond the elbow into the forearm. However, there is controversy as to whether the posterior radial collateral artery extends as a single trunk below the elbow or if it terminates more proximally with only a rich vascular plexus extending beyond the elbow. The purpose of this study was to revisit the artery's anatomy in the region of the elbow and to study its distribution in the forearm. Using latex and barium-gelatin injections of the posterior radial collateral artery in ten cadaveric upper limbs, it was observed that terminal branching of the artery occurred 4.5 cm proximal to the lateral epicondyle of the humerus. Distal to the epicondyle, the terminal branches of the posterior radial collateral artery were seen to fan out as finely arborized branches supplying the lateral forearm skin. No single, constant vascular trunk to the forearm skin could be identified. Furthermore, in its distribution toward the periphery, the terminal branches of the posterior radial collateral artery took an increasingly superficial course. Proximal to the epicondyle, the vessels lay deep within the subcutaneous fat, whereas distal to the epicondyle, they were very close to skin. These findings suggest that lateral forearm skin cannot be islanded without risk of vascular disruption and that the distally sited flap should include skin proximal to the epicondyle for safety.

Protective role of melatonin and retinol palmitate in oxidative stress and hyperlipidemic nephropathy induced by adriamycin in rats.

We have studied the effects of melatonin and retinol palmitate (RP) on the nephropathy and oxidative stress induced by a single and high dose of adriamycin (AD) in Wistar male rats. A dose of melatonin (75 microg/kg/day) and a dose of RP (0.25 g oily solution/kg/day, s.c.) were injected 3 and 9 days before and after the administration of AD (25 mg/kg, i.p.), respectively. After the decapitation, samples were taken from the neck vascular trunk in order to determine the triglycerides, total cholesterol, phospholipids, HDL-cholesterol, total proteins, urea, lipoperoxides, and reduced glutathione (GSH). We estimated the lipoperoxide and glutathione (GSH) contents in renal homogenates, and the excretion of proteins in urine over a 24 hr period. The administration of AD caused significant increases in proteinuria and in the other parameters studied [lipids (triglycerides, total cholesterol, phospholipids, and HDL-cholesterol), non-protein nitrogen compounds, and lipoperoxides]. AD increased the lipoperoxide content, but it decreased the GSH content in the kidney. Both melatonin and RP, although melatonin more significantly, decreased the intensity of the changes produced by the administration of AD alone. In fact, melatonin was quite efficient in reducing the formation of lipoperoxides, restoring renal GSH content and decreasing remarkably the severity of proteinuria. These results support the powerful antioxidant action of melatonin at renal level and a lower antioxidant action of retinol. Likewise, these data reinforce the hypothesis which supports the pathogenetic role and the close relation between the oxidative stress and the expression of the nephropathy induced by AD. However, in spite of this obvious antioxidant effect of melatonin in the kidney, additional studies are required to establish accurately the role of this pineal indole in the regulation and dynamics of the antioxidative defense enzyme system, which neutralizes the damaging effect of free radicals, both endogenous and exogenous, in this organ.

Study of the arterial vascularisation of the medial tibial condyle in the fetus.

Varus deformity of the knee is common in young children who have suffered from fulminating purpura. This study was directed at the anatomic features of the vascularisation of the upper end of the tibia that might account for such deformation. It was based on the dissection of 28 anatomic specimens prepared by injection of Indian ink into the vascular trunk. 16 specimens were diaphanised for better analysis of the intracartilaginous distribution of the vessels. The study showed that the vascularisation of the medial condyle of the tibia is poor and of terminal nature, which may explain the occurrence of ischemic growth disorders following fulminating purpura.

Imaging of the vertebrobasilar system by transcranial color-coded real-time sonography

The vertebrobasilar system was investigated in 75 persons by TCCS to evaluate the applicability and diagnostic capacity of this transcranial Duplex technique. Transforaminal and transtemporal acoustic windows were employed to identify the vertebral arteries, basilar artery (PCA) and major branches of the vertebrobasilar system. The frequency of identifying the basilar artery and the PCA ranged from 84 to 94% but was poor for the distal segment of the basilar artery (45.3%). The origin of the basilar artery was disclosed by transcranial Duplex sonography at an average depth of 7.0 cm (range 6.0 to 8.0 cm). The assignment of the obtained flow signals to specific vascular segments was improved by this new technique. In addition, four persons received a maximum of six intravenous injections of a transpulmonary stable sonographic contrast agent (SHU 508 A) to enhance Doppler signal intensity derived from the vertebrobasilar system. The vascular trunk and all major branches of the vertebrobasilar system were identified in these four persons. We conclude that TCCS of the vertebrobasilar system will improve reliability of transcranial sonographic examination.

Decision-making in Curative Rectum Carcinoma Surgery

Rectal carcinomas are increasingly treated by more and more differentiated regimens. Until the 1970s, the rectal excision was standard, whereas in 58% sphincter-saving procedures were performed during the last years. Locoregional recurrences are the main problem of surgical treatment for rectum carcinomas. They are of decisive importance for the patients. Without locoregional recurrence during the first two years, the overall five-year survival is 85% which decreases tremendously to 23% in case of a locoregional recurrence. Overall, this rate depends primarily on patho-histological parameters of the primary, as well as on therapeutic modalities and quality, too. For this reason, the arguments for routine neo- or adjuvant radio-(chemo-)therapy, increasingly arising during the last two years, is debatable. Global recommendations do not realize that low rates of locoregional recurrences may be achieved by surgery alone, e.g., 13% in the surgical Department of the University of Erlangen. However, these patients do include some groups with increased risk, for example, those who have positive lymph nodes along the course of a named vascular trunk (18%). These patients at increased risk may profit from adjuvant-radio-(chemo-)therapy. This is not yet, however, proven by any prospective study.

Reconstruction of mandibular and floor of mouth defects using the trapezius osteomyocutaneous flap.

The trapezius osteomyocutaneous island flap has evolved in postablative head and neck reconstruction as a versatile and hardy local flap which can provide intraoral lining, well-vascularized bone, and muscle bulk for the reconstruction of a complex defect. This investigative study examines the anatomy of 20 osteomyocutaneous flaps in 10 fresh cadavers and in 8 clinical patients. In our series, 80 percent (type I) of the major vascular pedicle arose from the thyrocervical trunk. In 20 percent (type II), the major pedicle arose separately from the subclavian artery. The regions perfused by the vascular trunk were further examined with microopaque and Prussian blue injections through the transverse cervical artery. Consistent areas of cutaneous staining as well as bony staining were noted over the shoulder, arm, and back and into the scapula itself. Experience with eight clinical applications of this osteomyocutaneous flap resulted in successful healing with an excellent aesthetic and functional result. Long-term follow-up was maintained on the patients for up to 36 months. Panorex radiographs and biopsies of the grafted bone were obtained on several patients. These disclosed evidence of bony remodeling and viable bone tissue. Tetracycline labeling also revealed evidence of active bony turnover.

Circulatory adaptation to bimodal respiration in the dipnoan lungfish.

In the dipnoan lungfish, Protopterus aethiopicus, P. annectens, and Lepidosiren paradoxa, the ductus is a short powerful muscular vascular trunk forming a channel for communication between the systemic and pulmonary circulations. In structure, the dipnoan ductus is very similar to the ductus arteriosus (Botalli) in the mammal. Innervation is abundant, consisting of myelinated and nonmyelinated nerve fibers issuing, at least in part, from the vagus. Neurons are present in the adventitia, and numerous nerve profiles, filled with small agranular vesicles, are closely associated with the myocytes, suggesting strong cholinergic control. Perfusion of the ductus in vitro using hypoxic saline causes it to dilate; conversely it is constricted by alpha-agonists. Dopamine and prostaglandin E2 are potent dilators, whereas the beta-agonist, isoproterenol, and acetylcholine are less powerful. A vasomotor segment has been identified on the pulmonary artery (PAVS) close to its junction with the ductus. Its location and structure are similar to the corresponding segment in amphibians and reptiles. It is innervated by endings filled with small clear vesicles. Granular vesicle cells are also present within the adventitia. The PAVS is constricted by acetylcholine. As in amphibians, alpha-agonists and hypoxic saline are without vasomotor effects. Based on the anatomic and physiological observations, a concept of cyclic perfusion of the gas exchangers in Dipnoi is proposed. During the alternation between air breathing (emersion) and apneic phases (immersion), the pattern of the circulation in the lungfish oscillates between that of a tetrapod and a fish.