Lajos Patonay

The clinical anatomy of the sinus node artery

BACKGROUND Our basic aim was to describe the topographic relation between the sinus node artery and the superior posterior border of the interatrial septum with regard to the sinus node dysfunction that follows the superior transseptal approach to the mitral valve. METHODS During our study 50 human hearts without previous pathologic alterations were analyzed. The position of the sinus node and the course of the sinus node artery were investigated. For identification of the origin of the artery, selective coronary angiograms were performed. The course of sinus node artery and its topographic relation to the interatrial septum was identified by the dry dissections of the hearts. Based on histologic and dry dissected specimens the exact position of the sinus node was determined. RESULTS We found that the sinus node artery originates from the right coronary artery in 66% of examined cases and from the left coronary artery in 34% of cases. The sinus node artery crosses the superior posterior border of the interatrial septum in 54% of cases. CONCLUSIONS Our results were compared with clinical studies focusing the incidence of the sinus rhythm disturbance after the superior transseptal approach. The incidence of rhythm disturbance varies from 52% to 60% of cases. Comparing our morphologic and clinical results we can state that the risk for intraoperative damage to the sinus node artery during the superior transseptal approach to the mitral valve is high.

Topographic microsurgical anatomy of the paraclinoid carotid artery.

In this publication, the authors describe the microanatomic topography of the entire paraclinoid area with respect to the paraclinoid segment of the internal carotid artery and its surrounding anatomical structures. Special attention was given to the borders of the paraclinoid area, cavernous sinus, arterial vessels, and cranial nerves passing through the region. The paraclinoid region was defined as a pyramid-formed space formed by the dural covering of the anterior clinoid process. The superior border is formed by the continuity of the anterior petroclinoid fold, anteriorly on the superior surface of the anterior clinoid process and medially in the direction of the diaphragma sellae. This dural sheet encircles the internal carotid artery and forms the so-called distal dural ring of the internal carotid artery. The medial border of the paraclinoid region is formed by the body of the sphenoid bone and the adjacent periosteal sheet. The inferior border is formed by a fibrous plate between the middle and anterior clinoid processes. This so-called proximal dural ring separates the venous compartments of the cavernous area from the paraclinoid area. The lateral border is formed by the lateral surface of the anterior clinoid process with its dural covering. The arterial supply of this region is provided by branches of the intracavernous carotid segment and the ophthalmic artery. The important nerves in close vicinity to the paraclinoidal area are the optic and the oculomotor nerves. Understanding and knowledge of the topographic anatomy of the paraclinoid area is essential for microsurgical exposure of this region.

Intraosseous territory of the facial artery in the maxilla and anterior mandible: Implications for allotransplantation

AIM The aim of this anatomical study was to define the intraosseous vascular territory of the facial artery. The clinical issue is whether ipsilateral facial artery anastomosis will guarantee blood supply to the ipsi- and contralateral mandibular symphyses and maxillae in allotransplantation. MATERIAL AND METHODS Of 10 human cadaveric heads, the left facial artery was injected with a positive contrast agent. The maxillae and mandibular symphyses were investigated with cone-beam computed tomography (CBCT). RESULTS Each ipsilateral maxilla and mandibular bone segment showed contrast medium in the intraosseous vessels. In 50% of cases, this was also the case on the contralateral side of the maxilla and anterior mandible. CONCLUSIONS The maxillae and the mandibular symphyses receive ipsilateral blood supply from the facial artery and, in 50% of cases, also from the contralateral facial artery. Internal maxillary artery anastomosis is not required for a vascularized maxillary bone flap. Additionally, involvement of the submental artery is not needed for a mandibular symphyseal bone flap.

Endoscopic anatomical study of the arachnoid architecture on the base of the skull. Part I: The anterior and middle cranial fossa

Abstract Minimally invasive neurosurgery requires a detailed knowledge of microstructures, such as the arachnoid membranes. In spite of many articles addressing arachnoid membranes, its detailed organization is still not well described. The aim of this study is to investigate the topography of the arachnoid in the anterior cranial fossa and the middle cranial fossa. Rigid endoscopes were introduced through defined keyhole craniotomies, to explore the arachnoid structures in 110 fresh human cadavers. We describe the topography and relationship to neurovascular structures and suggest an intuitive terminology of the arachnoid. We demonstrate an “arachnoid membrane system”, which consists of the outer arachnoid and 23 inner arachnoid membranes in the anterior fossa and the middle fossa. The inner membranes are arranged in two “arachnoid membrane groups” in the examined regions. The first is the carotid membrane group, located in the suprasellar region, consisting of seven paired and three unpaired inner membranes and the outer arachnoid on its base. The second is the Sylvian membrane group, composed of three inner membranes of the Sylvian fissure and completed by the outer arachnoid. Our findings should be very helpful in understanding the complex organization of the cranial arachnoid, which is mandatory for the safe and effective use of minimally invasive endoscopic techniques.

Histamine and H1 -histamine receptors faster venous circulation.

The study has analysed the action of histamine in the rabbit venous system and evaluated its potential role in contraction during increased venous pressure. We have found that a great variety exists in histamine sensitivity and H1‐histamine receptor expression in various types of rabbit veins. Veins of the extremities (saphenous vein, femoral vein, axillary vein) and abdomen (common iliac vein, inferior vena cava) responded to histamine by a prominent, concentration‐dependent force generation, whereas great thoracic veins (subclavian vein, superior vena cavas, intrathoracic part of inferior vena cava) and a pelvic vein (external iliac vein) exhibited slight sensitivity to exogenous histamine. The lack of reactivity to histamine was not due to increased activity of nitric oxide synthase (NOS) or heme oxygenase‐1. H1‐histamine receptor expression of veins correlated well with the histamine‐induced contractions. Voltage‐dependent calcium channels mediated mainly the histamine‐induced force generation of saphenous vein, whereas it did not act in the inferior vena cava. In contrast, the receptor‐operated channels were not involved in this response in either vein. Tyrosine phosphorylation occurred markedly in response to histamine in the saphenous vein, but not in the inferior vena cava. Histamine induced a prominent ρ kinase activation in both vessels. Protein kinase C and mitogen‐activated protein kinase (MAPK) were not implicated in the histamine‐induced intracellular calcium sensitization. Importantly, transient clamping of the femoral vein in animals caused a short‐term constriction, which was inhibited by H1‐histamine receptor antagonist in vivo. Furthermore, a significantly greater histamine immunopositivity was detected in veins after stretching compared to the resting state. We conclude that histamine receptor density adapts to the actual requirements of the circulation, and histamine liberated by the venous wall during increased venous pressure contributes to the contraction of vessels, providing a force for the venous return.

Hand perfusion with 99mTc-HSA in patients expecting to undergo coronary bypass surgery: Elaboration of a new complex diagnostic protocol for the safe removal of a radial artery graft

BackgroundThe Allen test is used worldwide for radial artery graft removal. The postoperative examination of our patients’ hand function and circulation proved that beside the transient neurological complications chronic hand circulatory disorders may arise. AimTo develop a non-invasive method suitable for an objective evaluation of the hands circulation to make it possible to use radial arteries safely for the revascularization of coronary arteries. MethodsWe examined 35 patients. After selective compression of the radial and ulnar arteries of both hands, we injected 400 MBq 99mTc-HSA intravenously and acquired 240 images, each of 1 s. After 30 s we released the ulnar artery first, and after 120 s the radial artery, too. Then computer analysis was performed. ResultsThe patients could be divided into two groups. In the majority of them, releasing only the ulnar artery resulted in a good circulation of the fingers. It meant that the time–activity curve rapidly reached its maximum, and the activity did not change even after releasing the radial artery. In a smaller proportion of the patients the activity of the fingers increased only slowly, and did not reach a plateau even after 30 s. Following the release of the radial artery a further increase in the activity could be observed. We assume that the latter patient group is at risk of consequent circulatory disorder of the fingers after the removal of the radial artery, whereas in the former group the artery could be removed safely. ConclusionsHand perfusion with 99mTc-HSA is useful in patients selected for coronary bypass operations, so we recommend the introduction of this method as a routine examination before the removal of the radial artery in patients with an abnormal Allen test.

Endoscopic approach-routes in the posterior fossa cisterns through the retrosigmoid keyhole craniotomy: an anatomical study

Endoscopy in cerebellopontine angle surgery is an increasingly used technique. Despite of its advantages, the shortcomings arising from the complex anatomy of the posterior fossa are still preventing its widespread use. To overcome these drawbacks, the goal of this study was to define the anatomy of different endoscopic approaches through the retrosigmoid craniotomy and their limitations by surgical windows. Anatomical dissections were performed on 25 fresh human cadavers to describe the main approach-routes. Surgical windows are spaces surrounded by neurovascular structures acting as a natural frame and providing access to deeper structures. The approach-routes are trajectories starting at the craniotomy and pointing to the lesion, passing through certain windows. Twelve different windows could be identified along four endoscopic approach-routes. The superior route provides access to the structures of the upper pons, lower mesencephalon, and the upper neurovascular complex through the suprameatal, superior cerebellar, and infratrigeminal windows. The supratentorial route leads to the basilar tip and some of the suprasellar structures via the ipsi- and contralateral oculomotor and dorsum sellae windows. The central endoscopic route provides access to the middle pons and the middle neurovascular complex through the inframeatal, AICA, and basilar windows. The inferior endoscopic route is the pathway to the medulla oblongata and the lower neurovascular complex through the accessory, hypoglossal, and foramen magnum windows. The anatomy and limitations of each surgical windows were described in detail. These informations are essential for safe application of endoscopy in posterior fossa surgery through the retrosigmoid approach.

Applied anatomy of a minimally invasive muscle-splitting approach to posterior C1-C2 fusion: an anatomical feasibility study.

AbstractPurpose To describe the applied anatomy of a minimally invasive muscle-splitting approach used to reach the posterior aspect of the C1–C2 complex.Summary of background dataAtlantoaxial fusion using a midline posterior approach and polyaxial screw and rod system is widely used. Although minimally invasive variations of this technique have been recently reported, the complex applied anatomy of these approaches has not been described. The C1–C2 complex represents an unique challenge because of its bony and vascular anatomy. In this study, the applied anatomy and feasibility of this technique are examined on cadavers.MethodsThe microsurgical anatomy of the upper cervical spine is examined on a formalin-fixed and on a fresh cadaver. The muscle-splitting approach is performed on 12 fresh cadavers using this technique.ResultsThe minimally invasive muscle-splitting approach is described in detail. Relevant anatomy and bony landmarks that aid screw placement in C1 and C2 could be well visualized. Using this approach, we were able to reach the lateral mass of the atlas and the inferior articular process and pars interarticularis of the axis in all of the nine cadavers. We placed mini polyaxial screws in C1 lateral mass and C2 pars interarticularis in four cadavers according to the technique described by Harms and Melcher.Conclusions Using this approach, it was possible to reach the posterior aspect of C1 and C2; the relevant anatomy needed to perform a C1–C2 fusion could be well visualized.

Endoscopic anatomical study of the arachnoid architecture on the base of the skull. Part II: Level of the tentorium, posterior fossa and the craniovertebral junction

Abstract Interest in surgical anatomy of arachnoid membranes is relatively new and became more important with the development of endoscopic techniques in neurosurgery. In the first part we introduced the term “arachnoid membrane system” and “arachnoid membrane groups” and described them in the anterior and middle cranial fossa. The objective of this second part is to discuss the arachnoid membranes of the tentorial level, posterior fossa and the craniovertebral junction. Rigid endoscopes were introduced through defined keyhole craniotomies to explore the arachnoid in 127 fresh human cadavers. We defined 12 inner membranes that are arranged in three membrane groups. The “tentorial membrane group” consists of five paired membranes forming an almost complete barrier between the supra- and infratentorial spaces. The “clival membrane group” consists of three membranes and completes the separation created by the tentorial group. The superior part of the “perimedullary group” located around the medulla oblongata and consists of three inner membranes. The inferior part located in the craniovertebral junction consisting of four membranes. Intracranial arachnoid membranes are constant and defined structures that are well arranged in distinct groups. These new findings are essential in understanding the three-dimensional architecture of the arachnoid and its importance in endoscopic neurosurgery.

Endoscopic anatomy of the intracisternal oculomotor nerve: a new segmentation based on the topography of the arachnoid membranes

Abstract Objective: The aim of our study was to investigate the detailed endoscopic anatomy of the intracisternal portion of the oculomotor nerve and to update the present knowledge of its related anatomy with the newest research on the topography of the arachnoid membrane system of the skull base. Methods: This study was performed on 50 fresh human cadaveric specimens post-mortem not more than 72 h. In each specimen, the intracranial arterial system was injected with red gelatin solution. We used the endoscope-controlled and endoscope-assisted microsurgical techniques applied through the minimally invasive supraorbital keyhole craniotomy to perform our dissections. Results: We divided the intracisternal oculomotor nerve into three segments in this study. These are the interpeduncular segment, located in the interpeduncular fossa and surrounded by dens arachnoid trabeculae around the thalamoperforating arteries; the tentorial segment, located between the posterior cerebral and superior cerebellar arteries and the posterior petroclinoid fold and surrounded by the elements of the clival and tentorial arachnoid membrane groups; and the trigonal segment located on the surface of the oculomotor trigone between the posterior petroclinoid fold and the dural exit of the nerve into the cavernous sinus and surrounded by the posteriorly located membranes of the carotid membrane group. Conclusions: Our findings support the more accurate understanding of the physiology of the arachnoid membrane system and the pathophysiology of space-occupying lesions in the region of the oculomotor nerve. Therefore, our results may support performing more atraumatic surgery in this area.