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Biomedical subjects

R H Anderson

Publications and source records attributed to R H Anderson.

At least 199 records · Page 11Linked to original sources
PubMed1995

What factors affect ventricular performance after a Fontan-type operation?

Postoperative conditions after a Fontan-type operation, particularly as they affect results in the early term, are thought to depend on factors such as the state of pulmonary circulation and ventricular function. In this study, we attempted to determine the factors that influence ventricular characteristics in the middle term after Fontan-type procedures. Catheterization was performed at a mean of 15 months after operation in 57 patients with univentricular atrioventricular connection who underwent the operation between 1.0 and 22.6 years of age. End-diastolic volume, end-systolic volume, ejection fraction, and end-diastolic pressure of the systemic ventricle were analyzed together with an estimation of the systemic flow index. These parameters were influenced significantly by the presence of atrioventricular valve insufficiency. The morphologically left ventricle showed a better ejection fraction than did the morphologically right ventricle, whereas the systemic flow index was greater in patients undergoing total cavopulmonary connection than in those receiving an atriopulmonary connection. Young age was significantly associated with a better postoperative contractility, whereas the potential for impaired ventricular compliance was suggested in several patients undergoing operation after 4 years of age. On the basis of our results, we conclude that total cavopulmonary connection performed at a young age should be the surgical procedure of choice and that atrioventricular insufficiency must be treated properly at, and even after, the initial definitive repair.

Adolescent↗
PubMed1995

The surgical anatomy of coronary venous return in hearts with isomeric atrial appendages.

Although absence of the coronary sinus is widely recognized in hearts with isomerism of the right atrial appendages, little attention has been paid to the fashion of the venous return from the heart itself. In this study, the arrangement of coronary venous return was investigated in 99 specimens with isomeric right and 49 with isomeric left appendages. In the normal heart, the coronary veins consist of a circumflex component within the atrioventricular groove and longitudinal components on the ventricular mass. The circumflex venous system was seen in 44 hearts with isomerism of left appendages (90%), but 23 of these hearts lacked the anatomic features of the coronary sinus. Circumflex veins were entirely lacking in the other 10% of hearts with isomeric left appendages and in all those with isomeric right appendages. In these hearts, longitudinal veins drained independently into the atria in three patterns. The first was a direct connection, with the venous orifice opening between the trabeculations of the atrial wall immediately having crossed the atrioventricular groove. The second was a crooked return, with the vein running an intramural course along the atrioventricular groove. The third was a distant connection, reaching superiorly to the smooth-walled atrial component after running an intramural course. Intramural courses were seen in 19% of the longitudinal veins, such veins being found in 62% of all hearts with no circumflex venous system. These findings, which to the best of our knowledge have never previously been recognized in detail, almost certainly have potential surgical significance.

Coronary Vessel Anomalies↗
PubMed1995

Left ventricular structures in atrioventricular septal defect associated with isomerism of atrial appendages compared with similar features with usual atrial arrangement.

In patients with isomeric atrial appendages, regurgitation of atrioventricular valves is recognized clinically as one of the risk factors that militate against successful achievement of definitive repairs. To determine whether this reflected anatomic features, we investigated 91 specimens with atrioventricular septal defect that had a common atrioventricular valve and biventricular atrioventricular connections. Of these specimens, 35 had isomeric right appendages, 23 showed isomeric left appendages, and 33 had usual atrial arrangement. We measured either the size or location of the supporting papillary muscles and the circumference of the mural leaflet within the morphologically systemic ventricle, as well as the length of outlet, inlet, and so-called scooped dimensions of the muscular ventricular septum. Presence of a solitary papillary muscle, or deviation of the attachments of the papillary muscles, was more frequent in hearts with isomeric right appendages. Values for the diameter and lengths of the papillary muscles were significantly smaller in hearts with isomeric right appendages compared with those with usual atrial arrangement (p < 0.001), as were the distances between the papillary muscles (p < 0.002) and the circumference of the mural leaflet (p < 0.001). The proportional length of ventricular outlet was longer in the setting of isomeric right appendages than in the other groups (p < 0.001), whereas the extent of septal scooping showed no differences among these three groups. We conclude that these structural features could be factors in the known insufficiency of the common atrioventricular valve and the ventricular dysfunction in patients with isomeric right appendages.

Heart Atria↗
PubMed1995

The architecture of the atrioventricular conduction axis in dog compared to man: its significance to ablation of the atrioventricular nodal approaches.

UNLABELLED: AV Node in Dog and Man. INTRODUCTION: Advances in treating patients with dual atrioventricular nodal pathways have called for a better understanding of the morphology of the approaches to the atrioventricular node. In this respect, it has recently been suggested that, in dog, anatomically discrete muscle bundles originating from the sinus node represent the substrate of the dual pathways recognized electrophysiologically in patients with atrioventricular nodal reentrant tachycardia. This concept is at odds with most anatomic studies of the human specialized atrioventricular junctional area. In this study, therefore, we studied histologically the junctional area in dog hearts, comparing them with our own findings in human heart and the descriptions of the earliest investigators. METHODS AND RESULTS: Five dog and six human hearts were prepared for histology and sectioned serially in different planes. Reconstructions were then made from each of three dog and two human hearts sectioned in orthogonal planes. Gross differences in the anatomy of the atrioventricular junctional area and in the structure of the conduction system were obvious between dog and human hearts. The penetrating portion of the conduction axis was longer in the dog, being much more extensively embedded in the central fibrous body. The atrioventricular node, in both dog and man, was composed of a zone of transitional cells overlying a compact region. The zone of transitional cells in the dog was more extensive posteriorly than anteriorly. No bundles insulated anatomically by fibrous tissue were found either in the internodal atrial myocardium or in the approaches to the atrioventricular node. Our findings in both dog and man are comparable with the initial descriptions of the atrioventricular junctional area. CONCLUSION: Although the disposition of the conduction system in dog and man is basically similar, there are important differences which relate to the gross anatomy. The anatomic substrate for functional duality of the inputs to the atrioventricular node remains unclear, since our study confirms that the concept of insulated atrionodal tract has no morphologic basis.

Animals↗
PubMed1995

Assessment of congenital heart defects by dynamic three-dimensional echocardiography: methods of data acquisition and clinical potential.

To evaluate the use of three-dimensional (3D) echocardiography in the diagnosis of congenital heart defects, we studied 238 patients aged 3 days to 19 years (mean 4.3 years) with normal hearts (n=13) or a variety of congenital heart defects (n=225). Three different modalities of data acquisition suitable for 3D reconstruction were applied. For parallel scanning, the transducer is held in a 6-cm long scan frame and then moved over the thorax, or in the subcostal position, by a stepper motor using 0.5-mm steps with acquisition of perpendicular parallel images of the heart. For rotational scanning, the transducer is rotated at sectors of 2 degrees over a span of 180 degrees. For fan-like scanning, the transducer is moved in an arc 45 degrees each way from its vertical axis. Movement of the transducer is computer-controlled and performed with electrocardiographic and respiratory gating. Between 80 and 120 slices of the heart are thus obtained, which form the 3D dataset. This dataset can then be ¿sectioned¿ in any desired plane, thus permitting generation of views simulating intraoperative perspectives. Ventricular septal defects and atrioventricular valves can be displayed as viewed via the atrium. Muscular ventricular septal defects can be viewed as seen through a ventriculotomy. Obstruction in the left ventricular outflow tract can be viewed as via an aortotomy, and so on. We concluded that this new imaging modality has a vast potential and may facilitate planning of intracardiac surgery.

Adolescent↗
PubMed1995

Architecture of atrial musculature in humans.

OBJECTIVE: To investigate the gross arrangement of the principal muscular bundles of the two atria, and to suggest how it may contribute to contraction and spread of atrial excitation. DESIGN: A prospective analysis based on anatomical examination of adult human hearts. SETTING: A national heart and lung institute and a tertiary referral centre for cardiac disease. MATERIAL: 9 normal postmortem human hearts. METHODS: Dissection of atrial muscles with macrophotography. RESUltS--The atrial walls consist of circumferential and longitudinal muscular bundles, the former being arranged at the base of the atria with the latter predominating in the parietal walls. The muscular bundles in the right atrium are larger than those in the left. The main muscles forming the right atrial wall are the terminal crest and terminal pectinate muscles. The terminal crest, the most obvious muscle, is arranged longitudinally with its pectinate muscles connecting to the musculature of the atrioventricular vestibule. No structure resembling the terminal crest is seen in the left atrium. Instead the left atrial wall is composed of intermingled series of muscles, chief of these being the interatrial band and the septoatrial bundle. The former is arranged circumferentially at the atrial base, while the latter is mainly longitudinal. The wall of the right atrium is not of uniform thickness because of the presence of the terminal crest and its pectinate muscles on its internal surface. By contrast, the left atrial wall is much more uniform and its average thickness is greater than that of the right atrium. The rim of the oval fossa is the most important muscular structure on the septal surface and is formed by the infolded atrial walls. The other principal muscles of the atria attach to it, so that the rim provides mechanical support for overall movement of the atrial walls. Comparison of the gross arrangement of the atrial musculature with earlier echocardiographic measurements showed that this arrangement of the muscle explains movement of the atrioventricular ring and overall atrial contraction, and provides a suitable substrate for preferential conduction. CONCLUSION: The anatomical features of the atrial musculature explain the known facts concerning atrial contraction and preferential conduction.

Autopsy↗
PubMed1995

Comparison of three dimensional echocardiographic findings with anatomical specimens of various congenitally malformed hearts.

OBJECTIVE: To compare the reconstructions obtained by three dimensional echocardiography with the anatomical specimens used to generate the echocardiograms. DESIGN: The heart specimens were immersed in a water bath and imaged with a 5 MHz echocardiographic transducer mounted into a scan frame which allowed the transducer to travel a total distance of 4.4 cm in steps of 0.25 mm. The transducer records a tomographic slice at each incremental level thus producing 176 parallel slices of the heart to form the dataset. Reconstruction of the anatomical structures of the heart in a three dimensional format is achieved by means of different grey scales. MATERIALS: 72 specimens of either normal or various congenitally malformed hearts. RESULTS: Good quality echocardiographic pictures were obtained, permitting three dimensional reconstructions in each heart. The cardiac chambers and valves could be displayed in a three dimensional format which accurately displayed the internal anatomy of the specimens. No artefacts, such as spurious septal defects, were produced in specimens with intact septums. The atrioventricular valvar leaflets, however, appeared thicker in the images than they were in the specimens. CONCLUSIONS: Three dimensional echocardiography accurately displays the anatomy of normal and congenitally malformed hearts.

Echocardiography↗
PubMed1995

The earliest site of atrial activation in patients with isomeric appendages.

BACKGROUND: The sinus node is known to be duplicated in hearts with bilateral right appendages, but its site is uncertain when both appendages are of morphologically left pattern. OBJECTIVE: To determine the earliest site of activation of the atria, and to assess this site of activation relative to the anticipated location of the sinus node in patients with isomeric atrial appendages. STUDY DESIGN: Electrophysiological recordings by epicardial mapping during operations through a median sternotomy. PATIENTS: Since 1987, 44 consecutive patients with isomeric right appendages and 23 with isomeric left appendages. RESULTS: In 77% of the patients with isomeric right appendages, the site of earliest activation was superiorly located at the junction of one or other atrium and a superior caval vein; in other words, in the anticipated site of a sinus node. In contrast, an inferior site of earliest activation at the junction of an atrium with an hepatic vein was most common in patients with isomeric left appendages (56%). The site of earliest activation was not related to the veno-atrial junctions in six patients with isomeric right appendages (14%), nor in five with isomeric left appendages (22%). Moreover, in six patients with isomeric right appendages (13%), and three with isomeric left appendages (13%), additional sites of earliest activation were observed when the dominant site was suppressed. The locations of the earliest activation observed by epicardial mapping did not always accord with those expected from the preoperative electrophysiological examination, nor did they always match the anticipated site of the sinus node as documented by previous histological investigations. CONCLUSIONS: Epicardial mapping showed marked variation in functional arrangement of the earliest atrial activation. This information could be of future use when planning surgical procedures.

Electrocardiography↗
PubMed1995

Morphology of the sinus node in human and mouse hearts with isomerism of the atrial appendages.

BACKGROUND: The location of the sinus node is known to be at best abnormal, or at worst unknown, in patients with isomerism of the morphologically left atrial appendage. In contrast, the sinus node is known to be an excellent histological marker of the morphologically right appendage, being duplicated in those with right isomerism. The aim of the study was to investigate this condition further in fetal human and mouse hearts. METHODS: Serial histological sections of the area anticipated to contain the sinus node were studied in hearts with isomerism of the atrial appendages taken from 14 human fetuses and 13 iv/iv mice, using 12 mouse hearts with normally arranged or mirror imaged atrial chambers for controls. RESULTS: All hearts with isomerism of the right appendages (two human and four mouse) had bilateral sinus nodes. The cases with isomerism of the left appendages (12 human and nine mouse) showed absence of a recognisable sinus node except in four cases (19%) in which a small remnant of the node was found. In three of these cases, it was related postero-inferiorly to the superior cavoatrial junction. CONCLUSIONS: The concept of isomerism of the atrial appendages is endorsed by findings on the morphology of the sinus node, this being the most reliable histological criterion for existence of a morphologically right atrium. A small proportion of hearts with left isomerism had a structure resembling the sinus node, but it was hypoplastic and displaced postero-inferiorly, distant from its expected position had the hearts possessed an incompletely formed morphologically right appendage.

Adult↗
PubMed1995

Echocardiographic-anatomical correlations in aorto-left ventricular tunnel.

OBJECTIVE: To investigate the echocardiographic, morphological, and histological appearances of aorto-left ventricular tunnel observed in four fetal hearts and compare the findings with those reported in older patients with the malformation. BACKGROUND: Previous studies have concentrated on clinical features of the malformation from birth to adult life and have speculated on either its embryological formation or its acquisition during late intrauterine life. The presentation of a large series of cases in fetal life is a unique opportunity to study the malformation at an early stage in its natural course. METHODS: A retrospective study was performed of four cases of aorto-left ventricular tunnel discovered among 872 cases of congenital abnormalities diagnosed at a tertiary centre for fetal echocardiography. Detailed echocardiographic and anatomical observations were made of the malformation as identified during fetal life. The precise anatomical arrangement was determined and compared with previous descriptions found in journals published in English. RESULTS: In fetal life, as after birth, the malformation is characterised by enlargement and hypertrophy of the left ventricle, enlargement of the aortic root, and free regurgitation at the level of the aortic valve. Anatomical abnormalities are found at the aortic ventriculoarterial and sinutubular junctions as well as in the intervening aortic wall. These are unrelated to necrosis, ischaemia, or the presence of mucopolysaccharides. CONCLUSIONS: The lesion is a developmental abnormality that should be reliably diagnosed by fetal echocardiography combined with colour flow Doppler echocardiography during the mid-trimester. The exact anatomical relations clarified by this study are pertinent to diagnosis and subsequent surgical correction.

Aorta↗
PubMed1995

Study of the afferent pathways from the rectum with a new distention control device.

Quantitative studies of the afferent pathways from hollow viscera have been limited by the lack of an easily controlled, reproducible visceral stimulus. We adapted a slow distention device to allow for rapid distention to study the afferent pathways from the rectum. The device produced a pressure increase of 10 mm Hg in 42 msec and of 20 mm Hg in 60 msec. We recorded cerebral evoked potentials (EPs) after rectal balloon distention in 17 healthy subjects. Several averages of 25 to 50 rectal distentions at 0.17-Hz frequency were recorded. The responses consisted of multiple peaks within 200 msec after stimulation. The mean latency of the initial positive peak was 44 msec, suggesting that a myelinated pathway was stimulated with mechanical rectal distention. Our device produced reliable and repeatable EPs that were independent of balloon characteristics or rectal pressures. EP recording after rectal stimulation may become a useful technique for the physiologic investigation of disorders such as fecal incontinence, constipation, irritable bowel syndrome, and chronic intestinal pseudo-obstruction.

Adult↗
PubMed1995

Immunohistochemical evaluation of the developing outflow tract in the rat: achieving aortic to mitral fibrous continuity.

OBJECTIVES: To study the development of aortic to mitral fibrous continuity in the normal rat heart. METHODS: The hearts and great vessels of normally developed rat embryos and fetuses aged between 13.25 and 19.75 days of gestation were studied in conjunction with those of newborns aged 2 and 7 days post-partum. Standard histological methods and monoclonal antibodies raised against alpha smooth muscle actin (clone 1A4) and ventricular beta myosin heavy chain were used to demonstrate the ventricular outlets, ventriculo-arterial junction, inner heart curve and aortic infundibulum from the early stages of aortopulmonary septation to attainment of their definitive morphology. RESULTS: The two antibodies demonstrated temporal specificity (actin specificity increased post-partum; myosin specificity maximal during fetal period) in the labelling of their intended structures which correlated with their known developmental profile. Full-thickness fibrous continuity between aortic and mitral valves was not complete until 1 week after birth. After ventricular septation was complete, and thereafter towards the end of fetal life and beyond, separation was maintained by a muscular structure histologically identical to the vestigial netro-aortic root branch of the conduction tissue, a structure known to be derived from the primitive ventricular myocardium within the environs of the inner heart curve. CONCLUSIONS: Ventricular septation (occurring relatively early) and the attainment of fibrous continuity (occurring relatively late in development) are two independent processes. Muscular tissue separating left-sided arterial and atrioventricular valves is not derived from the aortic infundibulum but from the inner heart curve. Persistence of this structure is a feature of normal rat heart development and needs to be recognised when working with rodent-based animal models of congenital heart disease aimed at studying the disruption of the development of the ventricular outflow tracts.

Actins↗
PubMed1995

The innervation of the human myocardium at birth.

In order to delineate the type and distribution of autonomic nerves within the atrial and ventricular myocardium of the neonatal human heart, numerous samples of atrial and ventricular myocardium from 4 neonatal human hearts with no cardiac anomaly, freshly obtained at necropsy, were processed and studied using immunohistochemical and enzyme histochemical techniques. The antisera included those used to demonstrate protein gene product (PGP) 9.5 as a general neural marker, dopamine beta-hydroxylase (DBH) and tyrosine hydroxylase (TH) as indicators for presumptive sympathetic neural tissue, and neuropeptide Y (NPY). A histochemical technique was used to reveal tissue cholinesterase activity. Numerous PGP-immunoreactive (PGP-IR) nerves were seen in the atrial myocardium, forming perivascular plexuses and lying in close apposition to myocardial cells. Fewer PGP-IR nerves were found amongst the myocardium of the ventricles. Both DBH-IR and TH-IR nerves demonstrated a similar pattern of distribution as that of PGP-IR nerves; in the atria, however, they were less numerous, while in the ventricles, their density approximated to that of PGP-IR nerves. Relatively few NPY-IR nerves were observed either in the atrial or the ventricular myocardium. The density of acetylcholinesterase (AChE) positive nerves in the walls of the atria was less than that of PGP-IR nerves although their distribution patterns were similar. In the ventricles, AChE positive nerves were rarely observed. It is concluded that the neonatal human heart possesses a rich supply of autonomic nerves. The atria possess at least two populations of nerves, presumably sympathetic and vagal, whereas the walls of the ventricles are innervated principally by presumptive sympathetic nerves.

Acetylcholinesterase↗
PubMed1995

Is the morphologically right atrioventricular valve tricuspid?

BACKGROUND AND AIM OF STUDY: Classification of the components of the right atrioventricular valve by its anatomical configuration is problematic and needs clarification. METHODS: Fifty hearts were studied so as to analyze carefully the structure of the right atrioventricular valve and to define its component parts. Cross-sectional echocardiograms were reviewed to demonstrate the valve in closed position, and reconstructed in three-dimensional fashion. RESULTS: The majority of specimens (62%) had three readily identifiable leaflets, but some (30%) could be described as having two leaflets while (8%) had four leaflets. The cross-sectional echocardiograms reviewed showed three definite lines of closure in all cases. CONCLUSIONS: The eccentric placement of the anterior papillary muscle causes the leaflets to close with three lines of apposition, and this makes the valve readily distinguishable from its mitral partner. When present, extra "scallops" in the structure of the right atrioventricular valve merely allow better coaption of the leaflets. So, although the term "cusp" is less than adequate as the descriptive basis for the structure of an atrioventricular valve, the right atrioventricular valve should still be considered to be tricuspid.

Echocardiography↗
PubMed1995

Common arterial trunk and pulmonary atresia: close developmental cousins? results from a teratogen induced animal model.

OBJECTIVES: To examine morphological similarities between "classically different" congenital heart lesion types induced in fetal rats by the cardiac teratogen N,N'-bis(dichloroacetyl)-1,8-octamethylenediamine (bis-diamine). METHODS: A single 200 mg oral dose of bis-diamine was given to 50 pregnant rats on the 9th gestational day. Eleven controls were fed an inert vehicle. Experimental and control rats were sacrificed from 15.4 days to term and embryos delivered by caesarean section. Age-matched embryos were processed for histology and sectioned at 7 microns. Cardiac morphology was compared between normal and bis-diamine exposed groups. RESULTS: Hearts from control embryos were morphologically normal. Those from bis-diamine treated embryos exhibited common arterial trunk (32%), overriding aortic valve with valvar pulmonary stenosis (40%) or infundibular atresia (4%), or ventricular septal defect (24%). Development of the outlet septum was affected in all hearts and the arterial duct was absent in 72% of cases. Whilst most hearts demonstrated the anatomy expected for their lesion, some with a common arterial valve demonstrated a pulmonary blood supply similar to that in human cases of pulmonary atresia, where, in the absence of an arterial duct, an essential systemic to pulmonary conduit was provided by a "persistent fifth aortic arch artery". In one such case the proximal part of the aortopulmonary septum was identified above a common valve. The septum was deviated to the left and was not continuous throughout the length of the arterial trunk, causing atresia of the pulmonary component. Others had muscular infundibular atresia but with a pulmonary blood supply arising directly from the solitary trunk as seen in common arterial trunk "type III". CONCLUSIONS: Bis-diamine consistently affects development of those structures which partition the arterial segment of the developing heart at one or more levels, often coexistent with agenesis of the sixth aortic arch arteries. Whilst the aortopulmonary and outlet septums were absent in most cases of common arterial trunk, some morphological duality was shared by classically different lesion types in these rat hearts, which may suggest a common aetiology for common arterial trunk "type III" and aortic overriding with absence of the outlet septum and pulmonary atresia.

Abnormalities, Drug-Induced↗