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Biomedical subjects

V M Nayak

Publications and source records attributed to V M Nayak.

At least 19 recordsLinked to original sources
PubMed2001

Aneurysm of the left atrial appendage.

A 43-year-old woman underwent excision of an aneurysm of the left atrial appendage, which had been causing cerebrovascular embolic episodes. We attribute the aneurysm to congenital dysplasia of the musculi pectinati in the left atrial appendage and of the bands of atrial muscle from which they arise. In Appendix I, we draw attention to the morphologically similar arrangements of inner and outer bands that emanate from a common transverse interatrial band and yield morphologically similar medial, descending, and ascending palm-leaf arrangements of musculi pectinati. In addition, we observe that the strap-like arrangements of musculi in both atria connect the outer band with the para-annular segment of the inner band. In Appendix II, we briefly review the literature concerning musculi pectinati and related bands.

Adult↗
PubMed2000

Hemitricuspid dysplasia in association with ventricular septal defect.

The tricuspid valve essentially consists of a straight septal leaflet and a curved mural leaflet that includes the anterior and posterior leaflets. A plane bisecting the septal and anterior leaflets divides the chordopapillary support of the tricuspid valve into 2 groups. One group is related to the bulbar and adjacent perimembranous and sinus components of the interventricular septum. The other is related to the trabecular septum and the adjacent free wall. We report our surgical findings in 5 patients who had dysplasia of the leaflets and chordopapillary support related to the bulbar, perimembranous, and sinus portions of the interventricular septum, in conjunction with a perimembranous ventricular septal defect. Phylogenic, ontogenic, and surgical implications of this association are discussed.

Adult↗
PubMed2000

Evolutionary anticipation of the human heart.

We have studied the comparative anatomy of hearts from fish, frog, turtle, snake, crocodile, birds (duck, chicken, quail), mammals (elephant, dolphin, sheep, goat, ox, baboon, wallaby, mouse, rabbit, possum, echidna) and man. The findings were analysed with respect to the mechanism of evolution of the heart.

Anatomy, Comparative↗
PubMed1999

Evolution of the ventricles.

We studied the evolution of ventricles by macroscopic examination of the hearts of marine cartilaginous and bony fish, and by angiocardiography and gross examination of the hearts of air-breathing freshwater fish, frogs, turtles, snakes, and crocodiles. A right-sided, thin-walled ventricular lumen is seen in the fish, frog, turtle, and snake. In fish, there is external symmetry of the ventricle, internal asymmetry, and a thick-walled left ventricle with a small inlet chamber. In animals such as frogs, turtles, and snakes, the left ventricle exists as a small-cavitied contractile sponge. The high pressure generated by this spongy left ventricle, the direction of the jet, the ventriculoarterial orientation, and the bulbar spiral valve in the frog help to separate the systemic and pulmonary circulations. In the crocodile, the right aorta is connected to the left ventricle, and there is a complete interventricular septum and an improved left ventricular lumen when compared with turtles and snakes. The heart is housed in a rigid pericardial cavity in the shark, possibly to protect it from changing underwater pressure. The pericardial cavity in various species permits movements of the heart-which vary depending on the ventriculoarterial orientation and need for the ventricle to generate torque or spin on the ejected blood- that favor run-off into the appropriate arteries and their branches. In the lower species, it is not clear whether the spongy myocardium contributes to myocardial oxygenation. In human beings, spongy myocardium constitutes a rare form of congenital heart disease.

Adult↗
PubMed1998

Bicuspidization for tricuspid stenosis.

Bicuspidization technique for rheumatic tricuspid stenosis based on the concept that the tricuspid valve has a straight (septal) and a curved (mural) leaflet is described. The fused commissures on either side of the septal leaflet are divided, resulting in separation of the two leaflets. The related anatomic and pathologic features are discussed.

Adult↗
PubMed1997

An anomalous muscle bundle inside the right atrium possibly related to the right venous valve.

The right and left venous valves of the sinoatrial orifice regulate the flow of blood from the sinus venosus to the atrium in pisces, amphibians, and reptiles. In aves, mammals and humans, the venous valve loses its hemodynamic function and hence has become the 'Cinderella' among heart valves, receiving attention only when congenital anomalies occur that are related to it. The right venous valve persists in humans as the crista terminalis, Eustachian and Thebesian valves. An intraluminal muscle band is described located inside the right atrium, and coursing in the line of the crista terminalis between the septum spurium and inferior vena cava. This abnormal band is possibly derived from the right venous valve.

Adolescent↗
PubMed1996

Comparative evaluation of cine-esophagogram with esophageal manometry in assessing esophageal motility in progressive systemic sclerosis.

BACKGROUND: Esophageal manometry is considered the gold standard in the diagnosis of esophageal motility disorders. Cine-esophagogram using barium is also a good investigation to screen patients for motor disorders of the esophagus. Comparison between these two investigations has not often been reported in patients with progressive systemic sclerosis (PSS). AIM: To determine relative merits of cine-esophagogram and esophageal manometry in detecting esophageal motor dysfunction in PSS patients. METHODS: Thirty-five patients with PSS irrespective of esophageal symptoms underwent esophageal manometry and cine-esophagogram, results and their were compared. RESULTS: Sensitivity and specificity of cine-esophagogram as compared to manometry were 96.1% (95% CI 88.7%-100%) and 55.5% (95% CI 23%-87.9%) respectively. Its positive predictive value was 86%. CONCLUSION: While esophageal manometry can identify esophageal motor disorder in PSS, cine-esophagogram can be resorted to in doubtful situations, for confirmation of diagnosis.

Adolescent↗
PubMed1995

Variations in the papillary muscles of the normal mitral valve and their surgical relevance.

A mid-mitral plane passing through the middle of the aortic and mural leaflets divides the chordopapillary support of the mitral valve into anterolateral and posteromedial halves. The papillary muscles of the mitral valve were studied in 100 human autopsy hearts collected at random. The anterolateral papillary support had 1 belly in 67 hearts, 2 in 27, 3 in 4, 4 in 1, and 5 in 1 heart. Likewise, the posteromedial papillary support had 1 muscle belly in 50 hearts, 2 in 36, 3 in 11, and 4 in 3. The single papillary muscles were conical, mammillated, flat topped, grooved, stepped, wavy, arched, sloped or saucerized. When there were two bellies they presented a two tiered, interlinked, parallel, arched, V, Y, or H configuration. Three papillary muscles formed a parallel, interlinked or arched arrangement; or two bellies were interlinked or formed a two tiered arrangement with the third belly separate. When four or five bellies existed, they were parallel or interlinked. In the anterolateral and posteromedial group, the papillary muscle bellies were mostly intraluminal in 14% and 11%, mostly intraluminal with the tip anchored in 19% and 28%, equally sessile and intraluminal in 54.5% and 41.5%, mostly sessile in 12.5% and 19.5%, respectively. In the anterolateral group 19% of papillary muscle bellies arose from the upper third of the ventricle, 79.5% from middle third, and 1.5% from lower third. The corresponding figures for posteromedial group are 6%, 92.5%, and 1.5%, respectively. Four to 22 chordae originated from the anterolateral papillary group, ending in 14 to 72 chordal insertions into the corresponding half of the valve. Likewise, 2 to 18 chordae arose from the posteromedial papillary group ended in 12 to 80 leaflet insertions. The chordae in each group are best considered in toto as a fan. The configuration of the fan is unique in each heart. Imaging techniques need to be refined to outline these variations more precisely. The relevance of chordopapillary variations in rheumatic heart disease, reparative procedures, papillary muscle dysfunction, mitral valve prolapse, mitral valve replacement, and use of mitral valve homograft for mitral/tricuspid replacement is discussed.

Cardiac Surgical Procedures↗
PubMed1995

Deringing procedure for congenital pulmonary vein stenosis.

We operated on a 14-year-old boy who had an echocardiographic diagnosis of ventricular septal defect. At surgery we found, in addition, an anomalous and obstructive intraventricular muscle bundle. Detection of a continuous thrill over the right pulmonary veins, prior to cardiopulmonary bypass, led to exploration of the left atrium. The ostia of the right superior and inferior pulmonary veins were impeded by circumferential membranous rings of endocardium with central stenotic openings. Excision of these annular rings relieved the obstruction. The left lung was drained by a long intrapericardial common venous channel that entered the left atrium through a stenotic ostium; excision of an annular ridge of endocardium restored normal flow. The patient remains asymptomatic after 23 months. The case is reported for the new deringing technique and the rarity of successful correction of congenital pulmonary vein stenosis.

Adolescent↗
PubMed1995

Sinoatrial malfusion presenting with caudal position of right atrial appendage.

A 5-year-old boy underwent surgery at our institution for closure of an ostium secundum atrial septal defect. Median sternotomy revealed that the right atrial appendage lay at the acute margin of the heart. Atriotomy revealed that the crista terminalis was also displaced clockwise, extending from the left of the superior vena caval orifice anteriorly along the interatrial septum, to the left border of the inferior vena cava; the musculi pectinati radiated forward and to the right. This highly unusual anomaly is likely due to clockwise rotation of the atrial portion in relation to the normally positioned sinus venarum portion of the atrium, which resulted in sinoatrial malfusion.

Child, Preschool↗
PubMed1995

Bicuspid evolution of the arterial and venous atrioventricular valves.

Atrioventricular valves were studied in pisces (shark), amphibians (frog), reptiles (turtle, snake and crocodile) and aves (duck, chicken and quail). Dog shark, Tiger shark and Hammerhead shark have a contractile common atrioventricular orifice with anterior and posterior bridging leaflets. Angel shark resembles the frog in having a contractile oval common atrioventricular orifice guarded by two lateral (right and left) and two central bridging (anterior and posterior) leaflets. In turtles and snakes the interatrial septation is complete. The common oval atrioventricular orifice is divided into two D-shaped orifices by the lower edge of the interatrial septum. Each orifice is guarded by a flap valve hanging down from the interatrial septum with rudimentary chordae tendinae, functionally corresponding to the septal leaflet of the human venous atrioventricular valve (VAVV) and the aortic leaflet of the human arterial atrioventricular valve (AAVV). There is no curved mural leaflet on either side related to curved contractile segments of the annuli. In crocodiles, the interventricular septation is complete. The VAVV is bicuspid with a prominent septal and diminutive mural component with no chordopapillary support. The AAVV is bicuspid with direct attachment of the fused commissural lines between the two leaflets to the ventricular musculature. In the aves, with four chambered hearts the VAVV has a curved mussular mural leaflet with a primitive muscular chorda and no septal leaflet. The AAVV resembles closely the human mitral valve. This study lends support to the view that VAVV and AAVV in man are similar in design and function with a D-shaped annulus and a skirt of leaflet tissue divisible into two functional units. The relatively straight part of the annuli suspend the straight leaflets; septal leafleft of the VAVV and aortic leaflet of the AAV. The curved annular components suspend the curved mural leaflets in both valves. Since this segment is contractile, the related mural leaflets of both valves need to have slits which split them into varying number of scallops to enable them to adapt themselves to the reduced systolic orifice and open widely during diastole. These scallops are best numbered as subsegments of the curved mural leaflet and not considered as separate leaflets. The curved leaflet of the VAVV needs to negotiate the acute border of the heart. Hence a major slit is usually present at this region which artificially divides it into an 'anterior' and 'posterior' portion resulting in assumption of a 'tricuspid' configuration.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗