Development of the atrioventricular junctional area in the human heart

The structure of the heart has been the subject of many observations since the beginnings of medical research. The first information regarding the existence of the conduction system of the heart was described by Purkinje and regarding the a-v node by Tawara. From the history regarding this structure it seems that this special system, so relevant to today™s invasive cardiologist, is not understood in full. With regards to the interventional electrophysiology on the basis of histological study we decided to evaluate in detail the morphology and the topography of the various portions of the a-v junction. In order to confirm this hypothesis we made observations on the autopsy material of 100 normal human hearts, both sexes from 16 weeks of foetal life to 105 years of age, in which no pathological changes or inborn faults were found. Sections were done containing the heart™s septum, stained using Masson™s method with Goldner™s modification. This research proves that the atrioventricular junction is a stable structure occurring in all hearts, undergoing involutionary changes with age, in which two main parts can be differentiated: the node and the bundle. The morphology of the node is very complex, because it is composed of three zones: the prenodal, the perinodal and the main, differing in cell structure and position. The topography of the node is generally stable, as it lies in the interatrial septum and always above the septal leaflet of the tricuspid valve. The structure of the bundle, in contrast to the node, is more stable and consists of the following parts: the penetrating, the non-branching and the branching. Its topography is also stable, as it lies in the membranous septum, mainly below the septal cusp of the tricuspid valve

Morphology of the tendon of Todaro within the human heart in ontogenesis

The tendon of Todaro, found in the right atrium of the heart, has considerable clinical importance in the fields of both cardiac surgery and invasive cardiology. The goal of this study is to examine the occurrence and degree of development of the tendon of Todaro in humans. Research was conducted on material consisting of 160 human hearts of both sexes from the age of 14 Hbd to 87 years of age. Classical anatomical methods were used and histological sections were prepared from 100 hearts of various age groups stained in Masson’s method with Goldner’s modification. The tendon of Todaro occurred in all examined hearts. In foetal hearts, in the area typical of the course of the tendon of Todaro, a very well-developed, “white-like” structure was observed, convexed into the lumen of the atrium. Histologically, this was young fibrous tissue with a characteristically large number of fibroblasts. Evenly in infants and newborns, a visible convex structure was also observed extending into the lumen of the right ventricle, however, to a lesser degree than in foetuses. In the group of hearts of young adults, it was also possible to follow the course of the tendon of Todaro macroscopically. However, the older the heart was, the less the convex was visible, and in older adults it was completely invisible. In histological sections, it was observed that with ageing the number of connective tissue cells decreased, and fibres forming the lining increased. In the hearts of older adults the tendon of Todaro formed very small ribbons of connective tissue. Histologically, only small numbers of cellular elements were noticed. In the adult heart the examined tendon was located the deepest and did not connect to the endocardium. We can conclude that tendon of Todaro is a stable structure, occurring in all examined hearts even when it is not macroscopically visible. Due to the morphological changes that affect the tendon of Todaro in human ontogenesis, for the cardiac surgeon, its relevance as an important topographical structure in the hearts of older adults is minimal

The topography of the subthebesian fossa in relation to neighbouring structures within the right atrium

The majority of anatomical structures within the heart during typical atrial flutters’ ablation, right sided accessory pathway ablation or slow pathway ablation are invisible or blurred. Therefore it is very important to know in details interior right atrial structures during such procedures. In the neighborhood of coronary sinus orifice small concavity is visible. This area, called subthebesian fossa, is placed between the os of coronary sinus, the orifice of vena cava inferior and tricuspid annulus. The fossa is on the way of typical atrial flutters’ reentrant circuit and is placed next to the isthmus area, which has become a target site for ablative therapy. Regarding the facts mentioned above we decided to examine the topography of this concavity in relation to neighboring structures. Research was conducted on material consisting of 45 human hearts of both sexes, from 19 to 71 years of age. The hearts came from patients whose death was not cardiologic in origin. The topography of the fossa was examined in relation to coronary sinus orifice (diameter A), vena cava inferior orifice (diameter B) and the attachment of the posterior leaflet of the tricuspid valve (diameter C). Besides we measured two perpendicular sizes in the inlet plane of the fossa. There were the longest size (diameter D) and the shortest size of the fossa (diameter E). We also defined deepness of the fossa (diameter F). Diameter A was from to 2 to 7 mm (avg. 4.9 ± 1.4 mm), diameter B from 2 to 8 mm (avg. 4.0 ± 1.6 mm) and diameter C from 5 to 9 mm (avg. 7.0 ± 1.5 mm). The longest size in inlet plane of the concavity (diameter D) was from 12 to 18 mm (avg.14.1 ± 1.7 mm) and shortest size (diameter E) was from 7 to 14 mm (avg. 9.0 ± 1.7 mm). The deepness of the fossa (diameter F) was from 2 to 7 mm (avg. 4.8 ± 1.2 mm). The subthebesian concavity is inconstant anatomical structure, occurring in all forty five examined hearts (100%). The shape and sizes of the subthebesian fossa were variable in examined group of hearts. Our data suggest that differences in diameters between subthebesian fossa and neighboring structures may have clinical importance during ablation procedure

The arrangement of muscle fibres in the region of the subthebesian fossa in the aspect of atrial flutter

The typical atrial flutter is the most common supraventricular tachycardia with reentrant circuit. This tachyarrythmia is based on macroreentry wave going around established anatomic landmarks. The reentry in the inferior right atrial wall passes through narrow isthmus, which is the goal for ablative therapy. The isthmus area is bordered anteriorly by the tricuspid valve and posteriorly by the inferior vena cava, coronary sinus, and eustachian ridge. Near to this area we can find anatomical structure, which can be very important during arising, perpetuation and curing of atrial flutter. The concavity, so-called subthebesian fossa [15], is on the way of typical atrial flutters’ reentrant circuit. Regarding the facts mentioned above we decided to examine the morphology and the arrangement of the muscle fibres in this fossa. Research was conducted on material consisting of 70 human hearts of both sexes from the age of 34 to 72 years. 50 hearts came from patients whose death was not cardiologic in origin. 20 hearts came from humans in whose common atrial flutter was confirmed. We observed the arrangement of muscle fibres in the area of subthebesian fossa. Besides we measured the size and deepness of the subthebesian fossa in both groups of hearts. We found that regular arrangement of muscle fibres within subthebesian fossa was present in 23 healthy human hearts (46%) and 7 cases (35%) of hearts with atrial flutter. The irregular arrangement of muscle fibres was observed in 27 hearts (54%) of control group and 13 hearts (65%) with dysrrhythmia. The thickness of the right atrial wall within the subthebesian fossa was very thin in 8 normal hearts (16%) and in 5 dysrrhythmic hearts (25%). The sizes of examined structure were variable in both groups of hearts, and are presented in the table. It seems that the subthebesian concavity can be the substrate for reentrant circuit during atrial flutter, and there could be such special arrangement of muscle fibres, which allows for microreentrant circuit to arise in this area

Histologic evaluation of the atrioventricular nodal artery in healthy humans and in patients with conduction disturbances

The anatomy of the conduction system of the heart so relevant in the contemporary invasive cardiology is not fully understood. It has turned out that ablation procedures bring new information as to its structure and function, but in some cases can result in complete a-v block. Atrioventricular nodal artery located within the nodal-perinodal tissue can probably be damaged during the ablation procedures. Therefore, we decided to explore in detail the morphology and the topography of the atrioventricular nodal artery in healthy humans and in patients with clinical traits of a-v conduction disturbances requiring permanent pacing. The microscopic study was carried out on 30 normal human hearts specimens (17F, 3M) from 17 to 86 years of age, and on 20 hearts with conduction disturbances (11F, 9M) from 39 to 85 years of age. We found that the number of the atrioventricular node arteries is different and independent of the extent that induces block causing conduction disturbances. The topography of the artery in perinodal zone was consistent in normal hearts, yet in hearts with conduction disturbances we observed about 2% of deviations in its location. It might be the reason for generation of iatrogenic complications after invasive cardiological procedures. The morphology revealed changes in 50% of the examined hearts and their vessel walls, which was declared to be connected with ageing. This correlated with certain stages of atherosclerosis as well as hypertension characteristic of elderly patients. We observed that in 33% of hearts from control group small parietal thrombi were detected and in 60% of paced group respectively. Hence, it seems that the procedures in perinodal zone should be performed in its proximal part because of a minor probability of direct and indirect (through nodal artery) damage of the atrioventricular structure of the junction

Anterior region of the atrioventricular perinodal area in relation to radiofrequency ablation procedures

Atrioventricular nodal reentry tachycardia base on reentry circulation in nodal-perinodal area. The radical treatment of choice is radiofrequency ablation. Procedure approached from the anterior-superior (fast) region sufficient a few seconds of energy delivery for success, however this can result in A-V block. The possibility that arrhythmias substrate may lie very superficially (success of ablation) and damage the normal structures (complication) in the perinodal region must be considered. In order to confirm this hypothesis we examined the autopsy material of 100 normal hearts, both sexes from 18 to 105 years of age (control) and 50 hearts with A-V total block 45-95 years of age (block). We paid attention to the morphology of the nodal artery (NA), atrial inputs (AI) and transitional inputs (TI). It was observed that NA at the level of the central fibrous body was positioned in 94% in the central and in 6% in the inferior part of Koch&#8217;s triangle. It was removed from the endocardium 3-6 mm in control and 2-5 mm in block group respectively (NS). In the perinodal area we distinguished AI that directly joined the A-V compact node: superficial (right part of the interatrial septum) or deep (left part). The former occurred in 100% of controls and in 80% of block groups (NS), and the latter in 80% of control group and in 34% in block respectively (p < 0.05). The real substrate of arrhythmia in anterior-superior region lies very superficially and far from the conduction tissue; NA in examined hearts was lying deep beneath the endocardium; ablation close to the node could result in A-V block

Preliminary study of external interatrial muscle fascicles

The atria are highly complex multidimensional structures composed of a heterogeneous branching network of subendocardial muscular bundles. The relief of the inner part of the right atrium includes the crista terminalis as well as multiple pectinate muscles that bridge the thinner atrial free walls and appendages. However, a handful of studies have focused attention on the role of the naturally occurring complexities of the atrial subendocardial muscle structures in the mechanisms of cardiac arrhythmias. In accordance with the facts mentioned above, it was decided to examine the morphology and topography of the external interatrial junctions and related structures in order to define the possible anatomical basis of impulse propagation in focal atrial fibrillation. Research was conducted on material consisting of 15 human hearts of both sexes (female - 6, male - 9) from 18 to 82 years of age. In addition we were concerned, on the basis of the history and electrocardiograph tracings, that none of the patients had shown focal and non-focal type of atrial fibrillation. The classic macroscopic methods of anatomical evaluation were used. The walls of the atria were prepared via a stereoscopic microscope, the pericardium and fatty tissue were eliminated from the surface of the atria, visualising muscle fibres linking both of the atria, and the beginnings and the endpoints of fascicles in the right and left atrium were estimated. The structure, large muscle bundle, was present in all examined hearts. The muscle fascicle was descending from the anterior wall of the right atrium just below the orifice of the superior vena cava. The fascicle, running towards the left atrium, divided into two branches, one of which joined with the superior fascicle from the posterior wall and created one running above the interatrial septum and infiltrating into the wall of the left atrium on its superior surface between the superior pulmonary veins. The other branch of the anterior fascicle was running across the anterior wall of the atria and it penetrated into the left atrium muscle in the region of the inferior pole of the left auricle outlet. On the posterior wall of the atria three types of interatrial fascicles were distinguished: unifascicular, bifascicular and trifascicular. The bifascicular type was the most frequent configuration (9 cases - 60.0%), in 5 cases it was trifascicular (33.3%) and finally the unifascicular configuration was observed in just 1 heart (6.7%). On the basis of our study we can conclude that the external interatrial fascicles are the constant structure of the heart,although they may have a variable morphology. Those structures could be responsible for physiological conduction between the atria and may play an important role in patients with atrial fibrillation

Primary pulmonary hypertension in pregnancy – a case report

Summary Primary pulmonary arterial hypertension, so called idiopathic pulmonary arterial hypertension (IPAH), is a rare and progressive disease with poor prognosis. Pregnancy in patients with this condition is hazardous and makes the prognosis significantly worse. According to WHO, IPAH is a contraindication to pregnancy because of high risk of maternal death and WHO advises to discuss termination in the event of pregnancy. Below we describe a case of a young woman at 16 weeks pregnancy with severe decompensated primary pulmonary hypertension. The patient was admitted to our department because of increasing dyspnoea and swollen legs occurring from 14th week of pregnancy. In the past the patient had been diagnosed with pulmonary hypertension, which had been defined during differential diagnostics as primary pulmonary hypertension. Echocardiographic examination over the last 4 years revealed stable mean pulmonary artery pressure (PAP) of about 50mmHg. The patient was treated efficiently with sildenafil for the last 2 years, but the therapy was discontinued after finding pregnancy. On admission it was established that pregnancy should be terminated. Other reasons of circulatory decompensation, uch as pulmonary embolism, cardiac tamponade or pulmonary diseases, were excluded

Morfologiczne aspekty jednojamowej prawokomorowej stałej stymulacji serca. Część III: Obraz histologiczny łącza p-k w sercu z zaburzeniami przewodzenia i stałą stymulacją

Morfologiczne aspekty stymulacji serca Wstęp: Serce i obserwacje dotyczące jego budowy sięgają początków rozwoju nauk medycznych. Jednakże struktura układu przewodzącego, tak istotna dla współczesnej kardiologii inwazyjnej, mimo wielu badań dotąd nie została w pełni poznana, zwłaszcza w sytuacjach patologicznych. Cel pracy: Szczegółowa ocena morfologii i topografii poszczególnych elementów łącza p-k na podstawie materiału prawidłowych i stymulowanych serc ludzkich. Materiał i metody: Badaniem objęto 100 serc ludzi dorosłych, obojga płci (41K, 59M), w wieku 20-105 lat. Na podstawie danych klinicznych badane serca zakwalifikowano do jednej z dwóch grup: prawidłowej (50) i stymulowanej (50). Pobierano wycinki zawierające trójkąt Kocha, które barwiono metodą Massona w modyfikacji Goldnera. Wyniki: W badanych sercach, w których uprzednio stwierdzano blok p-k I-III° zauważono istotne zmiany w porównaniu z grupą kontrolną. Mogły one dotyczyć układu przewodzącego bezpośrednio bądź tylko pośrednio. Zmiany w obszarze okołowęzłowym, które polegały na przerwaniu osi pomiędzy przedsionkiem a komórkami przejściowymi, stwierdzono tylko w 2% serc. Było to spowodowane dużym nagromadzeniem tkanki tłuszczowej, która rozsuwała włókna mięśniowe, co z kolei powodowało całkowity brak komórek przegrodowych w przegrodzie międzyprzedsionkowej. W 10% serc zmiany dotyczyły nie tylko strefy węzłowej, ale także okołowęzłowej. W polu pęczkowym zmiany odpowiedzialne za istnienie zaburzeń przewodzenia występowały częściej (88%). W tej grupie serc obserwowano zmiany bezpośrednie (88,6%) i pośrednie (11,4%). Zmiany morfologiczne w pęczku dzielącym się występowały w 22% badanych serc. Wnioski: Łącze przedsionkowo-komorowe to struktura stała, występująca we wszystkich sercach, która pod wpływem wieku ulega zmianom inwolucyjnym. Można w niej wyróżnić dwie główne części: węzeł p-k i pęczek p-k. Istnieją wykładniki morfologiczne tłumaczące istniejące zaburzenia przewodzenia, które mogą mieć charakter pierwotny (zwłóknienie, otłuszczenie układu przewodzącego) lub wtórny (zwapnienie pierścienia mitralnego lub aortalnego). (Folia Cardiol. 2000; 7: 187&#8211;194

Morfologiczne aspekty jednojamowej prawokomorowej stałej stymulacji serca. Część III: Obraz histologiczny łącza p-k w sercu z zaburzeniami przewodzenia i stałą stymulacją

Morfologiczne aspekty stymulacji serca Wstęp: Serce i obserwacje dotyczące jego budowy sięgają początków rozwoju nauk medycznych. Jednakże struktura układu przewodzącego, tak istotna dla współczesnej kardiologii inwazyjnej, mimo wielu badań dotąd nie została w pełni poznana, zwłaszcza w sytuacjach patologicznych. Cel pracy: Szczegółowa ocena morfologii i topografii poszczególnych elementów łącza p-k na podstawie materiału prawidłowych i stymulowanych serc ludzkich. Materiał i metody: Badaniem objęto 100 serc ludzi dorosłych, obojga płci (41K, 59M), w wieku 20-105 lat. Na podstawie danych klinicznych badane serca zakwalifikowano do jednej z dwóch grup: prawidłowej (50) i stymulowanej (50). Pobierano wycinki zawierające trójkąt Kocha, które barwiono metodą Massona w modyfikacji Goldnera. Wyniki: W badanych sercach, w których uprzednio stwierdzano blok p-k I-III° zauważono istotne zmiany w porównaniu z grupą kontrolną. Mogły one dotyczyć układu przewodzącego bezpośrednio bądź tylko pośrednio. Zmiany w obszarze okołowęzłowym, które polegały na przerwaniu osi pomiędzy przedsionkiem a komórkami przejściowymi, stwierdzono tylko w 2% serc. Było to spowodowane dużym nagromadzeniem tkanki tłuszczowej, która rozsuwała włókna mięśniowe, co z kolei powodowało całkowity brak komórek przegrodowych w przegrodzie międzyprzedsionkowej. W 10% serc zmiany dotyczyły nie tylko strefy węzłowej, ale także okołowęzłowej. W polu pęczkowym zmiany odpowiedzialne za istnienie zaburzeń przewodzenia występowały częściej (88%). W tej grupie serc obserwowano zmiany bezpośrednie (88,6%) i pośrednie (11,4%). Zmiany morfologiczne w pęczku dzielącym się występowały w 22% badanych serc. Wnioski: Łącze przedsionkowo-komorowe to struktura stała, występująca we wszystkich sercach, która pod wpływem wieku ulega zmianom inwolucyjnym. Można w niej wyróżnić dwie główne części: węzeł p-k i pęczek p-k. Istnieją wykładniki morfologiczne tłumaczące istniejące zaburzenia przewodzenia, które mogą mieć charakter pierwotny (zwłóknienie, otłuszczenie układu przewodzącego) lub wtórny (zwapnienie pierścienia mitralnego lub aortalnego). (Folia Cardiol. 2000; 7: 187&#8211;194