The modified Senning operation - surgical aspects

The advent of the arterial switch operation for the treatment of transposition of great arteries (TGA) made the atrial switch operation largely redundant and its use in the developed world is now confined to the atrial component of the double-switch operation for congenitally corrected TGA. In resource-limited countries, however, it remains relevant as a treatment option for patients presenting late with transposition and a regressed left ventricle. The operation is intricate with many potential pitfalls, and this “how I do it” article describes the operative steps in detail to enable surgeons to learn this procedure and make it a part of their surgical armamentarium.

Impact of COVID-19 pandemic on pediatric cardiac services in India

BACKGROUND

COVID-19 pandemic has disrupted pediatric cardiac services across the globe. Limited data are available on the impact of COVID.19 on pediatric cardiac care in India.

AIMS

The aims are to study the impact of COVID-19 pandemic on the care of children with heart disease in India in terms of number of outpatient visits, hospitalizations, catheter-based interventions, and cardiac surgeries.

SETTINGS AND DESIGN

This is a retrospective, multicentric, observational study.

METHODS

We collected monthly data on the number and characteristics of outpatient visits, hospitalizations, catheter-based interventions, and cardiac surgeries and major hospital statistics, over a period of 5 months (April to August 2020), which coincided with the first wave of COVID-19 pandemic in India and compared it with data from the corresponding months in 2019.

RESULTS

The outpatient visits across the 24 participating pediatric cardiac centers decreased by 74.5% in 2020 (n = 13,878) as compared to the corresponding period in 2019 (n = 54,213). The reduction in the number of hospitalizations, cardiac surgeries, and catheterization procedures was 66.8%, 73.0%, and 74.3%, respectively. The reduction in hospitalization was relatively less pronounced among neonates as compared to infants/children (47.6% vs. 70.1% reduction) and for emergency surgeries as compared to elective indications (27.8% vs. 79.2%). The overall in-hospital mortality was higher in 2020 (8.1%) as compared to 2019 (4.8%), with a higher postoperative mortality (9.1% vs. 4.3%).

CONCLUSIONS

The current COVID-19 pandemic significantly impacted the delivery of pediatric cardiac care across India with two-third reduction in hospitalizations and cardiac surgeries. In an already resource-constrained environment, the impact of such a massive reduction in the number of surgeries could be significant over the coming years. These findings may prove useful in formulating strategy to manage subsequent waves of ongoing COVID-19 pandemic.

Outcome of COVID-19-positive children with heart disease and grown-ups with congenital heart disease: A multicentric study from India

BACKGROUND

Outcome data of children with heart disease who acquired COVID-19 infection are limited.

AIMS

We sought to analyze outcome data and identify risk factors associated with mortality in children with heart disease and grown-ups with congenital heart disease (GUCH) who had a laboratory-confirmed COVID-19 infection.

SETTINGS AND DESIGN

This is a retrospective, multicentric, observational study.

MATERIALS AND METHODS

The study included children with heart disease and GUCH population, who presented with either symptomatic or asymptomatic COVID-19 infection to any of the participating centers. COVID-19-negative patients admitted to these centers constituted the control group.

RESULTS

From 24 pediatric cardiac centers across India, we included 94 patients with a median age of 12.5 (interquartile range 3-96) months and 49 (52.1%) patients were males. Majority (83 patients, 88.3%) were children. One-third of the patients (n = 31, 33.0%) had acyanotic congenital heart disease, and 41.5% (n = 39) were cyanotic, with > 80% of the patients being unoperated. Only 30 (31.9%) patients were symptomatic for COVID-19 infection, while the rest were incidentally detected positive on screening. A total of 13 patients died (case fatality rate: 13.8%). The in-hospital mortality rate among hospitalized patients was significantly higher among COVID-19-positive cases (13 of 48; 27.1%) as compared to COVID-negative admissions (9.2%) during the study period (P < 0.001). On multivariate analysis, the independent predictors of mortality among COVID-19-positive cases were severity of illness at admission (odds ratio [OR]: 535.7, 95% confidence interval [CI]: 6.9-41,605, P = 0.005) and lower socioeconomic class (OR: 29.5, 95% CI: 1.1-814.7, P = 0.046).

CONCLUSIONS

Children with heart disease are at a higher risk of death when they acquire COVID-19 infection. Systematic preventive measures and management strategies are needed for improving the outcomes.

A systematic approach to epicardial echocardiography in pediatric cardiac surgery: An important but underutilized intraoperative tool

Intraoperative echocardiography is an integral component of the peri-operative management of pediatric heart disease. It confirms the adequacy of surgery, identifies residual lesions, and can provide useful hemodynamic data. It, therefore, helps to decide on the need for revision of repair and guides the postoperative management strategy. Intraoperative echocardiography is done with the use of either an epicardial probe or a transesophageal probe. Epicardial echocardiography is a simple, useful modality and has the ability to perform imaging in cases where transesophageal echocardiography cannot be easily performed, for example, in low birth weight babies. We attempt to describe in detail the technique of epicardial echocardiography and the various views that we have found useful for a complete postsurgical evaluation. The limitations of the technique are also discussed in detail.

Double outlet of both ventricles: morphological, echocardiographic and surgical considerations

OBJECTIVES

To describe the morphology, echocardiographic features and surgical management of the entity appropriately described as 'double outlet of both ventricles'.

METHODS

Seven patients (5 males, age 0.5-7.5 months) were diagnosed to have a unique form of subarterial ventricular septal defect (VSD) and ventriculo-arterial connection, where a muscular outlet septum straddled the crest of the ventricular septum in a cruciate manner, such that both great arteries were equally committed to both ventricles. Diagnosis was established by echocardiography, with 6 patients submitted to surgical repair by means of intracardiac routing of the left ventricle to the aorta using 2 patches.

RESULTS

Surgical repair was successful in all 6 patients in whom it was attempted. In addition, 1 patient underwent concomitant repair of aortic coarctation, and 2 had closure of multiple VSDs. We lost 1 patient to follow-up after diagnosis. Follow-up with a range from 3 months to 8 years in the remaining patients revealed all to be clinically well with satisfactory growth of both outflow tracts.

CONCLUSIONS

We describe a series of patients with the ventriculo-arterial connection best described as 'double outlet of both ventricles'. Diagnosis is readily established by echocardiography. Good early and midterm results can be expected subsequent to surgical repair using 2 patches for interventricular septation.

Mid-Term Follow-Up of Neonatal Neochordal Reconstruction of Tricuspid Valve for Perinatal Chordal Rupture Causing Severe Tricuspid Valve Regurgitation

BACKGROUND

Papillary muscle rupture in the perinatal period is a rare event that leads to severe mitral or tricuspid insufficiency due to a flail leaflet. Neonatal tricuspid chordal reconstruction for this condition is rarely reported. Early recognition and treatment have the potential to be lifesaving. We present our surgical experience with five such patients, along with their midterm follow-up.

METHODS

Between August 2010 and November 2012, five neonates (aged 1-30 days) underwent surgery for severe atrioventricular valve regurgitation. All neonates had severe tricuspid regurgitation due to ruptured chordae. In addition, two had moderate mitral regurgitation; one due to ruptured chordae of the posterior mitral leaflet and the other due to prolapse of the anterior mitral leaflet. All underwent emergent surgery where the ruptured chordae to the anterior tricuspid leaflet were replaced with neochordae made with expanded polytetrafluoroethylene (ePTFE) suture. The mitral valve was repaired in two patients.

RESULTS

All patients survived surgery without the need for postoperative mechanical circulatory assist. Predischarge echocardiograms showed good coaptation of tricuspid and mitral leaflets with minimal regurgitation in all. At follow-up between 75 months to 102 months, four patients had excellent outcomes with less than mild tricuspid regurgitation. One child with flail tricuspid and mitral leaflets developed progressive tricuspid and mitral regurgitation requiring surgical re-repair at 20 months following the initial surgery.

CONCLUSION

Repair of chordal rupture of the tricuspid valve in neonates using ePTFE neo-chordae can provide acute salvage and gratifying midterm results in the management of this potentially fatal condition.

Valved conduits in the right ventricular outflow-the Achilles heel of congenital heart surgery!

Valved conduits play an important role in the reconstruction of the right ventricular outflow tract, but their limited longevity remains an unsolved problem for the congenital heart surgeon.

IACTS guidelines: practice of cardiovascular and thoracic surgery in the COVID-19 era

Patients undergoing cardiovascular and thoracic procedures are at an accentuated risk of higher morbidity and mortality, which are a consequence of the proliferative nature of the severe acute respiratory syndrome-corona virus 2 (SARS-CoV-2) on the lung vasculature, which in turn reflects as a cascading effect on the interdependent physiology of the cardiovascular and pulmonary organ systems. These are secondary to systemic inflammatory response syndrome and immunosuppressive responses to surgery and mechanical ventilation. Thus, the need to establish guidelines for the practice of cardiothoracic surgery which is safe for both the patient and the healthcare team presents as a priority, which is the mainstay of this article.

Pulmonary Valve Replacement in Repaired Tetralogy of Fallot Through Limited Left Anterolateral Thoracotomy: An Alternative to Repeat Sternotomy

We report two patients with repaired tetralogy of Fallot who underwent pulmonary valve replacement through a limited left anterolateral thoracotomy. We describe the technique in detail. Both patients were at risk of cardiac injury during repeat sternotomy. This approach reliably avoids the risk of cardiac injury during repeat sternotomy and appears to be safe, simple, and reproducible.

Arterial Switch Operation With Neoaortic Valve Replacement in a 13-Year Old Patient With Transposition of Great Arteries With Ventricular Septal Defect and Left Ventricular Outflow Tract Obstruction-A Case Report

The surgical management of d-transposition of great arteries (d-TGAs) with ventricular septal defect (VSD) and left ventricular outflow tract obstruction (LVOTO) is ever evolving and still remains a challenge because of wide anatomic variability, age of presentation, surgical options available, and their variable long-term results in different series. We describe a patient with d-TGA, VSD, and LVOTO who presented to us at 13 years of age and underwent an arterial switch operation along with neoaortic valve replacement with a mechanical prosthesis. The postoperative course was uneventful, and at hospital discharge, the echocardiogram was satisfactory. We present the pros and cons of this hitherto undescribed treatment option.

Left Superior Vena Cava Draining Into Left Atrium in Tetralogy of Fallot-Four Cases of a Rare Association

Persistent left superior vena cava is a common congenital anomaly of the thoracic venous system. Left superior vena cava draining into left atrium is a malformation of sinus venosus and caval system. The anomaly may be a cause of unexplained hypoxia even in adults. It may give rise to various diagnostic and technical challenges during cardiac catheterization and open-heart surgery. It is often detected serendipitously during diagnostic workup. Isolated left superior vena cava opening into left atrium is very commonly associated with other congenital heart defects. But tetralogy of Fallot is very rarely associated with persistent left superior vena cava which drains into left atrium. We report four such cases who underwent surgical correction successfully.

Atypical Left Ventricular Myxoma: Unusual Echocardiographic and Histopathological Features

Cardiac myxomas are the most common primary cardiac tumors and are typically attached to the interatrial septum. Left ventricular myxomas are exceedingly rare and presentation in children is all the more uncommon. We report a case of left ventricular myxoma with very atypical cystic appearance raising an initial suspicion of a hydatid cyst. Subsequently, cardiac magnetic resonance imaging was done, which ruled out the diagnosis of hydatid cyst. Complete surgical excision was done through transaortic and transmitral route. Histopathological examination revealed it to be a cardiac myxoma with vascular proliferation, which on echocardiography had appeared as a polycystic lesion. This is a very unusual histopathological presentation of cardiac myxoma.

Surgical Options for Uhl’s Anomaly

Background:

Uhl’s anomaly is an extremely rare congenital heart defect characterized by a near total absence of the myocardium of the parietal wall of the right ventricle. Few reports of surgical management exist in literature. We present three patients with this anomaly who were managed with different surgical strategies.

Patients and Methods:

Patient 1: This 43-month-old girl had maternal rubella syndrome with speech and hearing deficits and gross right heart failure. Diagnosis was made on echocardiography and magnetic resonance imaging. She underwent partial excision and plication of the right ventricular parietal wall and total cavopulmonary connection. Patient 2: This 19-month-old boy presented with progressive cyanosis and features of right heart failure. Diagnosis was confirmed on echocardiography. He underwent right ventricular exclusion by tricuspid valve closure and free wall plication followed by a bidirectional Glenn procedure. Patient 3: This 21-year-old male presented with right heart failure and cyanosis. Diagnosis was established with transesophageal echocardiography and magnetic resonance imaging. As the hemodynamics were not suitable for a Fontan conversion, a one and a half ventricle repair was done along with plication of the right ventricular free wall and tricuspid valve annuloplasty.

Results:

All three patients were extubated within 24 hours. Patients 2 and 3 were discharged relatively uneventfully, whereas patient 1 had a more prolonged stay due to transient hepatic failure. All were symptomatically and clinically improved on short-term follow-up.

Conclusion:

Uhl’s anomaly is an extremely rare condition with varied clinical presentation. Surgical exclusion of the right ventricle yields gratifying results; however, surgical technique has to be adapted to the individual patient.

Pandiastolic antegrade flow in patient with severe right ventricle to pulmonary artery conduit stenosis: An interesting phenomenon

In a post operative tetralogy of fallot (TOF) physiology patient, abnormal right ventricular (RV) function remains the greatest matter of concern. Due to restrictive RV diastolic dysfunction, there is detectable antegrade diastolic flow in the pulmonary artery during atrial systole. We report a case of 21 year old male patient with total correction done in infancy using right ventricle to pulmonary artery conduit. He was relatively asymptomatic with a unique pattern of antegrade diastolic flow in both early and late diastolic phases (pan diastolic). This physiology was supportive and made him relatively asymptomatic. We discuss the physiology and clinical implication of the same.

Reversible ventricular dysfunction in cyanotic heart disease

Ventricular dysfunction is a matter of concern for any preoperative cardiac patient. We describe 2 cases of cyanotic congenital heart disease (CCHD) awaiting on pump repair with hypoxia as a cause of ventricular dysfunction. Any Cyanotic Congenital heart disease presenting with ventricular dysfunction should be evaluated for treatable causes like hypoxia after exclusion of structural causes for the same.

Lutembacher syndrome with unroofed left superior vena cava: a diagnostic dilemma

Lutembacher syndrome involving the association of congenital atrial septal defect (ASD), usually of the ostium secundum variety, and mitral valve disease is a well-known entity. Its association with a coronary sinus, ASD, and a persistent left superior vena cava (LSVC) draining into the left atrium (LA) (Raghib syndrome) is rarely described in the literature. This association in a 15-year-old boy erroneously deemed to be inoperable before referral to the authors' hospital due to cyanosis in the presence of atrial septal defect (ASD) and mitral stenosis is described in this report. Evaluation by echocardiography followed by cine angiography confirmed the cause of cyanosis to be drainage of the LSVC into the LA together with an ASD and rheumatic mitral stenosis, a combination of Raghib and Lutembacher syndromes. The boy underwent successful surgical correction. The authors believe this is the second such case to be reported in the English literature and the first of its kind to be managed by surgical intervention.

Combined Bentall and modified Ravitch procedures in a patient with Marfan syndrome

Marfan syndrome is an inherited, connective-tissue disorder transmitted as an autosomal dominant trait. Cardinal features of the disorder include tall stature, ectopia lentis, mitral valve prolapse, aortic root dilatation, and aortic dissection. Pectus excavatum may exist as an isolated lesion or in association with a genetic syndrome such as Marfan syndrome. We report the successful management of a simultaneous correction of pectus excavatum and the underlying cardiovascular diseases.

Symptomatic giant left atrial aneurysm in a child: a rare entity

Isolated left atrial aneurysms are rare entities in clinical practice. Usually the condition is diagnosed in the second to fourth decades of life. The presence of such lesions in the pediatric age group is scantily described. We present a 2 year boy who presented with complaints of excessive irritability, respiratory distress and swelling of the feet. On examination, child was tachypnoeic with irregularly irregular rhythm. Echo showed a huge aneurysmal LA appendage with severe left ventricle dysfunction. The child underwent surgical resection for same. Findings were confirmed intraoperatively but he continued to have low cardiac output state after the surgery, with frequent arrhythmias and expired on day 7 of surgery. The case is reviewed and compared with the available English literature.

Unusual case of ruptured sinus of Valsalva: rupture into left ventricle cavity along with distortion of mitral valve requiring double valve replacement

We report a rare case of sinus of Valsalva aneurysm of left aortic sinus, which was bulging into left atrium (LA) distorting mitral valve and rupture into the left ventricle with severe aortic regurgitation in a 25 years old male patient. Due to the rupture, both aortic and mitral valves were irreparable and required a double valve replacement along with the closure of the neck of the aneurysmal cavity occupying the left atrial roof.

Giant congenital diverticulum of the right atrium

Congenital diverticulum of heart is a rare entity, which may arise from the atria, atrial appendages, coronary sinus or the ventricles. A 3-year-old child presented with history of early fatigability for 6 months and recent upper respiratory tract infection. Chest X-ray and echocardiogram revealed marked right atrial enlargement. At surgery, a right atrial diverticulum was excised under cardiopulmonary bypass. Pathology revealed thickened endocardium with edema and myocardial fiber hypertrophy. Our experience with this rare congenital disease is presented along with a review of the literature.

Comparison between transcatheter closure and minimally invasive surgery for fossa ovalis atrial septal defect: a single institutional experience

BACKGROUND

Although, conventional surgical closure of atrial septal defect (ASD) provides excellent results with very low mortality and morbidity, it leaves the scar of incision and postoperative pain. Newer treatment modalities like minimal invasive surgery and percutaneous closure are being increasingly used nowadays where available.

AIM

To compare the patient population, success, safety, and efficacy of transcatheter closure of ASD (Group A) with that of minimally invasive surgery (Port Access) (Group B).

METHODS

In this retrospective non-randomized study, a record of a total of 640 patients with diagnosis of ASD secundum between May 1997 and October 2006 were reviewed. A total of 470 out of 640 patients were selected for transcatheter closure (Group A) while 170 patients were taken for surgical closure by minimally invasive port access surgery (Group B). The safety and efficacy of two groups was evaluated on the basis of morbidity and mortality, duration of intensive care unit (ICU) stay, total duration of hospital stay, post-procedural complications, residual sequel at time of discharge, and residual flow across the ASD.

RESULTS

Success rate in two groups was 97.1% and 99.4%, respectively and had no statistically significant difference. Similarly major complication rate also had no difference in statistical significance (1.8% and 2.9% for Group A and B, respectively). Group B patients had longer hospital stay. A small but significant number of patients were not found suitable for device closure. This number is likely to decrease as experience with technique increases. Port access surgery is currently not possible in small children (femoral artery diameter 35 mm) due to difficulty in cannulation.

CONCLUSION

Percutaneous device closure of ASD can be offered as a treatment option in suitable patients. Port access is minimally invasive and an equally safe and effective alternative choice in ASDs with deficient rim in patient with appropriate age and weight.

A rare intrapericardial enterogenous cyst presenting in infancy

We report an infant with an intrapericardial enterogenous cyst, and discuss the differential diagnosis of intrapericardial cysts presenting in infancy.

Supramitral Ring: Good Prognosis in a Subset of Patients With Congenital Mitral Stenosis

BACKGROUND

Management of congenital stenotic mitral valvular abnormalities remains an important therapeutic challenge. Supramitral ring constitutes a small but inadequately described subset that has a relatively good outcome with appropriate management.

METHODS

Between 1996 and 2004, 15 patients with supramitral ring were managed in this institution. The demographic and clinical features, diagnostic modalities, morphology of the rings, and the surgical management were studied retrospectively.

RESULTS

Accurate preoperative diagnosis was possible by transthoracic echocardiography in 11 patients (73%). The associated anomalies were ventricular septal defects in 8 patients (53%) and abnormalities of the left ventricular outflow tract in 7 patients (47%). A circumferential supramitral ring, separate from the mitral valve, was present in 8 patients (53%). In the remaining, the ring was attached circumferentially to the anterior and the posterior mitral leaflets and was most densely adherent at the posteroinferior commissure in 4 of these 7 patients (57%). Complete excision of ring was possible in all cases, without damage to the mitral valve. There was 1 in-hospital death (6%). At a mean follow-up of 30 months, 14 survivors continue to do well, with no significant recurrence of mitral stenosis.

CONCLUSIONS

Patients with supramitral ring constitute a subset of patients with congenital mitral stenosis who have a relatively good prognosis. In many cases, the supramitral ring is entirely separate from the mitral valve, and when attached, it is usually most prominent at the posteroinferior commissure. In both cases, complete resection is surgically feasible and usually provides lasting relief.

Aortico-left ventricular tunnel: echocardiographic recognition

Aortico-left ventricular tunnel (ALVT) is a rare congenital malformation characterized by an abnormal communication between aorta and left ventricular cavity and the child presents with features of congestive heart failure in early infancy. We report the case of a 7-day-old baby who was diagnosed as a case of ALVT by echocardiography. The child was operated successfully and echocardiographic findings were confirmed.

Identification of the structural and functional determinants of the extracellular domain of the human follicle stimulating hormone receptor

The extracellular domain (ECD) of the human follicle-stimulating hormone receptor (hFSHR) is believed to be the major determinant of hormone selectivity. Different discrete, discontinuous regions on the ECD of the hFSHR have been suggested to be crucial for hormone binding. However, the role of the ECD in signal transduction is not well understood. This study provides some insight into these aspects of the structure-function relationship of the ECD of hFSHR. Ten peptides were selected from the ECD on the basis of their ability to be surface oriented, synthesized by the solid-phase method using fluorenylmethyloxycarbonyl chemistry, purified and characterized. They were further studied for their ability to modulate both human follicle-stimulating hormone (hFSH)-FSHR binding and cAMP generation. Competitive inhibition studies showed that, of all the peptides studied, peptides 285-300 and 297-310 hFSHR were able to inhibit hFSH binding to FSHR. Both peptides function as weak competitive inhibitors of hFSH-FSHR binding. Peptides 285-300 hFSHR, 216-235 hFSHR, 184-195 hFSHR, 79-89 hFSHR and 15-31 hFSHR were observed to inhibit FSH-induced cAMP production. In summary, this study suggests that discrete, functional domains of the ECD have a role in hormone binding and signal transduction. Region 285-300 has been identified as a novel region crucial for both FSH binding and cAMP generation.

Attempt to map the receptor binding sites of human follicle-stimulating hormone using disulfide peptides of its beta-subunit indicates major involvement of the regions around disulfide bonds Cys28-Cys82 and Cys32-Cys84 in receptor binding of the hormone

Follicle-stimulating hormone (FSH) is a heterodimeric glycoprotein hormone secreted by the anterior pituitary. It plays a very important role in folliculogenesis in females and is responsible for spermatogenesis in males. The alpha-subunit which is common within a species and the beta-subunit which is hormone-specific are held together by noncovalent association. This association is very essential for the biological activity of the hormone. Each of these subunits are highly cross-linked by disulfide bonds which appear to stabilize the tertiary structures required for the noncovalent association of the subunits to generate hormonal activity. This study was initiated to delineate the role of the disulfide bonds of hFSH beta in receptor binding of the hormone. Five intermolecular and one intramolecular disulfide peptides corresponding to the disulfide bonds found in hFSH beta were synthesized and screened along with their linear counterparts, for their ability to competitively inhibit the radiolabelled [125I]hFSH from binding to the FSH receptor containing membranes from the testis of immature rats. The disulfide peptides Cys28-Cys82 and Cys32-Cys84 were found to be the most potent in inhibiting radiolabelled hFSH from binding to its receptor. The results suggest the involvement of the regions around disulfide bonds Cys28-Cys82 and Cys32-Cys84 in receptor binding of the hormone. The studies also suggest the involvement of beta L2 and beta L3 loop regions in receptor binding of the hormone. This study is the first of its kind to use disulfide peptides rather than linear peptides to map the receptor binding regions of hFSH.

Disulfide bonds Cys(9)-Cys(57), Cys(34)-Cys(88) and Cys(38)-Cys(90) of the beta-subunit of human chorionic gonadotropin are crucial for heterodimer formation with the alpha-subunit: experimental evidence for the conclusions from the crystal structure of hCG

Human chorionic gonadotropin (hCG) is a heterodimeric glycoprotein hormone essential for the establishment and maintenance of pregnancy. The alpha- and beta-subunits of hCG are highly cross-linked internally by disulfide bonds that seem to stabilize the tertiary structures required for the noncovalent association of the subunits to generate hormonal activity. This paper describes the results of our studies on the role of the disulfide bonds of hCG-beta in heterodimer formation with the alpha-subunit. Six disulfide peptides incorporating each of the six disulfide bonds of hCG-beta were screened, along with their linear counterparts, for their ability to competitively inhibit the recombination of alpha- and beta-subunits. The disulfide peptides Cys (9-57), Cys (34-88) and Cys (38-90) were found to inhibit the alpha/beta recombination whereas the remaining three disulfide peptides viz. Cys (23-72), Cys (26-110) and Cys (93-100) did not exhibit any inhibition activity. Interestingly, none of the linear peptides could inhibit the alpha/beta recombination. Results clearly demonstrate that the disulfide bonds Cys(9)-Cys(57), Cys(34)-Cys(88) and Cys(38)-Cys(90) of the beta-subunit of hCG are crucial for heterodimer formation with the alpha-subunit thus providing experimental confirmation of the conclusions from the crystal structure of the hormone.

Effect of active immunization with the C-terminal 67-94 (R-28) region of human seminal plasma inhibin on the fecundity of adult male rabbits

PROBLEM

To characterize the specificity of antibodies to the synthetic C-terminal 67-94 (R-28) peptide of human seminal plasma inhibin (hSPI), and to examine the effect of active immunization on the fecundity of adult male animals.

METHOD OF STUDY

The specificity of R-28-DT antibodies was tested using enzyme-linked immunosorbent assay, immunohistochemical and immunofluorescence staining, and Western blotting. For fertility studies, adult male rats and rabbits were immunized and mated with females of the same strain.

RESULTS

Rabbit antibodies to R-28-DT recognized native hSPI, as demonstrated by sperm agglutination in vivo and in vitro, on the sperm head by immunofluorescence staining, and in the columnar epithelial cells of the prostate by immunohistochemical staining. Immunization with the R-28-DT conjugate elicited a poor antibody response in male rats and their fecundity remained unaffected, while in male rabbits it elicited a good immune response with reduction in their fertility.

CONCLUSION

R-28-DT antibodies recognized the native hSPI in the prostatic epithelium and agglutinated washed rat, rabbit, monkey, and human spermatozoa in vitro. Immunization of rabbits caused agglutination of spermatozoa resulting in a decrease in their fecundity. The conjugated R-28 peptide of hSPI offers promise as a male contraceptive.

A detailed study of the L2beta long-loop region of human chorionic gonadotrophin suggests it to be spatially close to, but not part of, the receptor-binding site

An in-depth study of the L2beta long-loop region of human chorionic gonadotrophin (hCG), earlier identified to be a conformational bioneutralization epitope and receptor-binding site of the hormone, was carried out. The linear 38-57 hCGbeta peptide and the corresponding cyclic disulphide peptide were synthesized and antipeptide antibodies developed. Binding studies with antibodies to the linear peptide, and with hCGbeta, hCG and human LH suggest that part of the region is buried at the alpha/beta interface and part exposed in hCG. Observation of the surface exposure of residues 47-53 from the crystal structure of hCG was confirmed by epitope mapping studies of the region. The region is not unique to hCG as a majority of the antibodies to both the linear and cyclic peptides did not exhibit the required specificity. Competitive inhibition studies with the linear and cyclic peptides failed to show inhibition of radiolabelled hCG binding to its receptors. However, both the antipeptide antibodies were able to bioneutralize the hormone in an in vivo assay. Taken together, these results seem to indicate that the L2beta long-loop region is not a receptor-binding site of hCG but spatially close to it.

Mapping the receptor binding regions of human chorionic gonadotropin (hCG) using disulfide peptides of its beta-subunit: possible involvement of the disulfide bonds Cys(9)-Cys(57) and Cys(23)-Cys(72) in receptor binding of the hormone

Human chorionic gonadotropin (hCG) is a heterodimeric glycoprotein hormone essential for the establishment and maintenance of pregnancy. The alpha- and beta-subunits of hCG are highly cross-linked internally by disulfide bonds which seem to stabilize the tertiary structures required for the noncovalent association of the subunits to generate hormonal activity. The purpose of this study was to delineate the role of the disulfide bonds of hCGbeta in receptor binding of the hormone. Six disulfide peptides incorporating each of the six disulfide bonds of hCGbeta were synthesized and screened, along with their linear counterparts, for their ability to competitively inhibit the binding of [125I] hCG to sheep ovarian corpora luteal LH/CG receptor. Disulfide peptide Cys (9-57) was found to be approximately 4-fold more potent than the most active of its linear counterparts in inhibiting radiolabeled hCG from binding to its receptor. Similarly, disulfide peptide Cys (23-72) exhibited receptor binding inhibition activity, whereas the constituent linear peptides were found to be inactive. The results suggest the involvement of the disulfide bonds Cys(9)-Cys(57) and Cys(23)-Cys(72) of the beta-subunit of hCG in receptor binding of the hormone. This study is the first of its kind to use disulfide peptides rather than linear peptides to map the receptor binding regions of hCG.

Constraints in the development of contraceptives for men

Considerable efforts have been made to develop a male contraceptive and the studies have provided very useful information in this field. At least five different strategies to develop a male contraceptive have been pursued, namely: inhibition of sperm production, interference with sperm function, interruption of sperm transport, prevention of sperm deposition, and prevention of sperm-egg interaction. Of all these approaches, inhibition of sperm production by using androgens either alone or in combination with progestins have given the most encouraging results. A number of clinical trials substantiate that it is indeed possible to have a reversible, effective and safe hormonal method of contraception. A postmeiotic and epididymal approach to interfere with sperm function or the secretory and metabolic processes of the epididymis is another attractive option of male contraceptive development. A number of chemical compounds have been identified which interfere with sperm function in the epididymis without affecting sperm production, however, the compounds evaluated so far were found to be toxic. Interruption of sperm transport through the vas either by vasectomy or percutaneous intravasal injection of liquids which form cure-in-place plugs is also an attractive option. However, reversibility of the methods is of concern in their wide scale use. The major constraint in developing a long-acting male contraceptive seems to be the need for greater investment for product development. The clinical trials for evaluating the efficacy and safety of the new products and formulations stretch over several years and require enormous financial commitment. Nevertheless, the long-term gain of having a long-acting reversible contraceptive for men is far greater than the financial commitments over few years. Male attitude towards using methods of family planning is much more favourable than originally believed. The pharmaceutical industry as well as the health care providers therefore have a greater responsibility. For early development of a contraceptive for men, it is essential to increase investment and simplify the drug regulatory procedures. The advent of newer technologies coupled with the convergent efforts of scientists will certainly make it possible to have an effective, safe and reversible male contraceptive in the near future.

Effect of immunization with synthetic peptide corresponding to region 1-17 of human seminal plasma inhibin on fertility of male rats

Immunization of adult male rats with a synthetic peptide corresponding to the region 1-17 of human seminal plasma inhibin (hSPI) resulted in agglutination of epididymal sperm, severely affecting the fertility of the animals (75% reduction in fertility as compared to control). This effect was found to be dependent on the antibody titer to hSPI. There was a significant rise in circulating follicle-stimulating hormone levels, with luteinizing hormone and testosterone levels remaining unaffected. The histology of the testes and other reproductive organs revealed that these organs remained unaltered. The N-terminal 1-17 amino acid peptide of hSPI may hold promise as an immunogen for male immunocontraception.

Significant intraoperative right ventricular outflow gradients after repair for tetralogy of Fallot: to revise or not to revise?

BACKGROUND

This study was performed to define alternative parameters for the management of intraoperative residual right ventricular outflow obstruction (RVOTO) after transatrial repair of tetralogy of Fallot (ToF) in order to differentiate those requiring immediate revision from those who do not.

METHODS

Since October 1995, 166 patients of ToF underwent transatrial repair. Postbypass residual RVOTO was assessed by surgeon's subjective impression, direct intracardiac pressure measurements, and intraoperative echocardiography (IOE). RVOTO was labeled "significant" whenever it exceeded a gradient of 40 mm Hg on IOE or right ventricular to left ventricular pressure ratio (pRV/LV) exceeded 0.85. Further, on IOE, significant RVOTO was defined "fixed", if there was no change in RVOT dimensions during the cardiac cycle, along with the presence of anatomic substrate for obstruction, and "dynamic" if RVOT dimensions increased appreciably in diastole. Postoperative course and follow-up echocardiograms of all patients were analyzed.

RESULTS

Significant RVOTO was detected in 58 (35%) patients (mean gradient 54 mm Hg). Seven (12%) of them with fixed obstruction (mean 46 mm Hg) underwent immediate surgical revision, while the remaining 51 patients with mean gradient of 78 mm Hg (including 10 patients with pRV/LV ratio of > or = 1.0) with dynamic obstruction did not undergo revision. There were six (3.6%) early deaths. Operative mortality and postoperative morbidity were not related to higher residual gradients, although the first 15 such patients had longer intensive care stay and inotropic support, in which this was done electively. On follow-up (mean 18.5 months), outflow gradients declined sharply (mean 16 mm Hg) irrespective of the severity of intraoperative gradients (p < 0.001). There were no reoperations or late deaths.

CONCLUSIONS

This study shows that: 1) existing parameters for immediate revision of residual RVOTO possibly need to be reviewed; 2) intraoperative echocardiography helps in differentiating "fixed" from "dynamic" obstruction and helps obviate needless revisions; and 3) dynamic RVOT gradients decline significantly irrespective of their severity after transatrial repair of ToF.

Sevoflurane for induction and intubation in children undergoing congenital cardiac surgery

The induction and intubation characteristics of sevoflurane were studied prospectively in 23 children, aged 3 months to 6 years (mean 24 +/- 20.25), undergoing repair of congenital cardiac defects. After premedication with syrup chloral hydrate (75mg/kg orally), anaesthesia was induced with 8% sevoflurane and 50% nitrous oxide in oxygen. Nasal endotracheal intubation was performed once the pupils were small and central, without the use of neuromuscular blocking agents or opioids. Characteristics of induction and intubating conditions were recorded. Induction time (from application of face mask to loss of eyelash reflex) was 43.7 +/- 4.57 secs (mean +/- SD). Mean intubation time was 149.1 +/- 15.6 secs. Intubating conditions were excellent in 21 patients (91.3%) and good in 2 patients (80.7%). Haemodynamic parameters (heart rate, rhythm, and systolic blood pressure) were recorded at loss of eyelash reflex, immediately before intubation and at 1, 3 and 5 min after intubation. All children remained haemodynamically stable throughout induction and there were no adverse airway events.