Biomedical subjects

S Radhakrishnan

Publications and source records attributed to S Radhakrishnan.

At least 37 records · Page 2Linked to original sources

PubMed2001

Left atrial and pulmonary artery wedge pressure monitoring during balloon mitral valvuloplasty.

OBJECTIVE: We tested the accuracy of pulmonary artery wedge (PAW) pressure as a guide to the degree of pulmonary venous hypertension. METHODS: Left atrial (LA) pressure and PAW pressure were analysed before and after balloon mitral valvuloplasty (BMV) in patients with rheumatic mitral stenosis. RESULTS: Correlations between LA and PAW pressures for a wave, v wave and mean pressure were excellent before BMV (r=0.96, r=0.97 and r=0.99 respectively) and after BMV (r=0.98, r=0.98 and r=1.00 respectively). The fall in mean LA pressure (11.3 +/- 7.9 mm Hg) and in mean PAW pressure (11.1 +/- 7.9 mm Hg) also correlated well. Correlation was good both before and after BMV when subgrouping was done based on average pulmonary vascular resistance and average LA mean pressure in each group. CONCLUSIONS: There is good correlation of PAW pressure with LA pressure even in the presence of pulmonary arterial or venous hypertension. It can replace LA pressure monitoring in any clinical setting.

Adult↗

PubMed2000

Total intravenous anesthesia with ketamine for pediatric interventional cardiac procedures.

OBJECTIVE: To evaluate the safety and efficacy of ketamine in pediatric patients undergoing interventional cardiac procedures. DESIGN: A retrospective clinical study. SETTING: A single, tertiary referral center. PARTICIPANTS: Patients (n = 107) undergoing interventional cardiac procedures between July 1996 and July 1998. INTERVENTIONS: Each patient received a bolus of ketamine, 1 mg/kg intravenously, followed by an infusion of 50 to 75 microg/kg/min for the duration of the procedure. MEASUREMENTS AND MAIN RESULTS: Hemodynamic and respiratory parameters were noted. All patients were breathing spontaneously. Average infusion dose of ketamine was 51.40+/-3.54 microg/kg/min (mean +/- standard deviation). Increases in heart rate and mean arterial pressure by more than 20% from baseline values were seen in 10 and 9 patients, respectively. Transient apnea and excessive salivation were seen in two patients each. Excessive movement of extremities was seen in six patients. There were no episodes of unpleasant dreams or hallucinations. There were two deaths (1.9%) related to the interventional procedures. CONCLUSION: The technique described is a simple, safe, and effective method for anesthetizing children in the cardiac catheterization laboratory for interventional procedures.

Adolescent↗

PubMed2000

Immediate and early results of closure of moderate to large patent arterial ducts using the new Amplatzer device.

OBJECTIVES: Our aim was to assess the immediate and short term results of closure of moderate and large patent arterial ducts using the self-expanding and repositionable Amplatzer device. METHOD: We attempted closure in 25 patients (10 Females and 15 males) using the Amplatzer occluder. Their median age was 48 months with a range from 8 months to 26 years and median weight of 14 kg with a range from 4.5 kg to 48 kg. The mean ductal diameter was 4.1 mm (S.D 1.51 mm). A 6F/7F long sheath was used to deliver the device. Follow up was performed with colour- flow mapping of the pulmonary trunk within 24 hours, at 3 months, and 6 months of closure. RESULTS: Of the 25 patients, the device was placed successfully in 23. Concurrent angiography showed immediate closure in 12 patients, while 8 had trivial shunting and 3 had mild shunting. Within 24 hours, Doppler examination revealed complete closure in all but three patients, who had a mild residual shunt. Two attempts were unsuccessful. Both these patients underwent successful surgical ligation. All except one patient were discharged on the next day. Of the 23 patients, 15 (65%) have been followed up for 3 months, while 8 (35%) have completed 6 months of follow-up. Of the three patients initially with mild residual flow, two had completely closed at 3 months The one remaining patient is yet to be seen at the 3 month follow-up. Thus, at 3 months, all patients studies had shown complete closure. CONCLUSION: Antegrade transcatheter closure using the Amplatzer duct occluder is an efficacious treatment for bigger patent arterial ducts. Long-term follow-up is necessary to show sustained benefits and confirm the absence of side effects.

Adolescent↗

PubMed2000

Acquisition and analysis of brainstem auditory evoked responses of normal and diseased subjects by spectral estimation.

Human brainstem auditory evoked responses (BAERs) are sensory evoked potentials that can be recorded within a few milliseconds following a transient acoustic stimulus (click signal). This paper suggests a novel technique to clearly demarcate normals and patients with complaints of vertigo and deafness by computing hitherto unused power spectral parameters from the BAER signals recorded on them. The BAER spectrum of normal subjects contains three main frequency components, i.e. low-, mid- and high-frequency components around 100, 500 and 1000 Hz, respectively, which is not so in the case of diseased subjects. The spectral parameters, i.e. the mean power frequency, median frequency, the ratios of the integrated power at dominant frequencies to that of the total power in spectrum and change in spectral power (CP) between these dominant frequency components are used to classify the recorded BAER signals into those of normals and the patients, and aid the clinician in quick and better diagnosis. The ranges of CP are estimated for the different groups and appear to be the most dominant parameter in the classification of the BAER signals.

Adolescent↗

PubMed2000

Role of molecular techniques in the detection of HBV DNA & HCV RNA among renal transplant recipients in India.

In this study we have investigated the occurrence of hepatitis B virus (HBV), hepatitis C virus (HCV) and hepatitis D virus (HDV) infections among 68 renal transplant recipients. Replicative HBV and replicative HCV infections were seen in 12 (17.6%) and 38 (55.9%) patients respectively, the difference was statistically significant (P < 0.001). Among the 38 HCV RNA+ individuals, anti-HCV was present only in 23. Anti-HCV in the absence of HCV RNA was detected in one patient. Anti-HDV antibody was seen in 2 (15.4%) of the 13 HBV infected individuals. Nine (13.2%) of the 68 individuals had replicative dual infection with HBV and HCV. Triple infection (HBV DNA+, HCV RNA+, anti-HDV+) was seen in 2 transplant recipients. There was significantly higher demonstration of replicative HCV (P < 0.001) in transplant recipients having elevated liver enzymes (n = 34) as compared to transplant recipients having normal liver enzyme levels (n = 34). Though not significant, a higher detection rate was also seen with replicative HBV infection and replicative dual infection among transplant recipients with elevated liver enzymes. The higher detection of HCV in renal transplant recipients by molecular techniques, emphasizes the need for HCV RNA testing. Further deliberate attempts to change practices to reduce this problem may also improve graft and patient survival in recipients.

Adolescent↗

PubMed2000

Non surgical closure of atrial septal defect using the Amplatzer septal occluder in children--feasibility and early results.

OBJECTIVE: To assess the feasibility and early results of Amplatzer septal occluder in children withy secundim atrial septal defect. SETTING: Tertiary care referral hospital in New Delhi. METHODS: Forty nine children under 12 years of age were diagnosed to be having fossa ovalis atrial septal defect. Forty nine patients underwent detailed 2D-Echocardiography and color Doppler interrogation for the possibility of non-surgical closure of ASD. Sixteen children between age 2.5-12 years (mean 6.5 years) were enrolled into the study. Their weight ranged from 10 kg to 42 kg and there were 9 males and 7 females. The remaining 33 were not considered suitable for device closure in echocardiography and were referred for surgery. RESULTS: All patients had more than 1.8 : 1 shunt. The device was successfully deployed in 13/16 patients. ASD stretched diameter ranged between 13 mm-30 mm (mean 15 mm) and the device size ranged between 14 mm-22 mm. One patient had fenestrated ASD, in this patient the largest of the defect was crossed and closed with 24 mm device resulting in closure of all three defects. We failed in three of our attempts, on one there were deficient inferior margins while in the other two cases the ASD stretched size was such that the device would have encroached upon adjacent structures, hence the procedure was abandoned. All these patients have been operated successfully. Complete abolition of shunt was seen in 38% patients in the immediate post deployment period. At 24 hours complete closure was seen in 12/13 (92%) patients while one patient had trivial residual shunting across the device. This patient also achieved complete closure of atrial shunting when evaluated at three months follow-up. CONCLUSION: Device closure of ASD is emerging as an alternative to surgical closure. However, with the currently available device only a limited number of atrial septal defects can be closed. Long-term studies are required to show sustained benefits and absence of side effects of this device.

Adolescent↗

PubMed2000

Transcatheter closure of patent ductus arteriosus.

OBJECTIVE: To present short and intermediate results of catheter closure of patent ductus artereiosus using spring coils and Amplatzer duct occluder. SETTING: Tertiary care referral hospital in New Delhi. METHOD: 121 patients were diagnosed to be having patency of the arterial duct between October 1996 and December 1999. Their ages ranged between 4 mo and 480 mo (mean 80.5 mo). Before August 1998 only spring coils were used as an alternative to surgical closure of the duct, whereas between August 1998 and December 1999 both coils and device were used. RESULTS: Spring coils were attempted in 48, Amplatzer duct occluder in 44 and 29 patients were referred for surgery. Coils were successfully deployed in 42/48 (87.5%) and device in 42/44 (95.5%) patients. Complete closure of the arterial duct was seen in 96% patients in the coil closure group at the end of one year and 100% closure was achieved in the device closure group at the end of 3 months in all the patients followed. Coil embolised in 11 patients, significant stenosis of left pulmonary occurred in one patient and severe hemolysis requiring blood transfusion occurred in one patient after coil closure. Six patients required a second procedure to close the residual shunt within 6 months of the initial coil deployment. One patient had loss of femoral artery pulses in right leg after device closure and required heparin infusion for 48 hours. There were 8 failed attempts. All these patients have been operated successfully. CONCLUSION: Percutaneous closure of the patent ductus arteriosus using Coils or the Amplatzer device is an acceptable method. Small residual shunts are common after the initial procedure especially after coil deployment but most close spontaneously.

Adolescent↗

PubMed2000

Prevalence of enterically transmitted hepatitis viruses in patients attending a tertiary--care hospital in south India.

The prevalance of enterically transmitted hepatitis viruses, namely, hepatitis A virus (HAV) and hepatitis E virus (HEV) were studied in 404 patients with acute hepatitis attending a tertiary-care hospital in south India. Presence of current HAV/HEV infection was ascertained by the demonstration of IgM antibodies. In 381 patients tested for both agents, HAV IgM was present in 51(13.3%) and HEV IgM present in 66(17.3%). There was dual infection in 3 males (0.8%). HEV infection was seen mostly in older children and adults with only 5.5% occurring in children < 12 years of age. HAV infection was commonly seen to occur in < 12 years of age group (52.7%). One hundred and twenty-six patients were from the Vellore region, among whom HAV and/or HEV aetiology was observed in 28.5%. In this region there did not appear to be any correlation between occurrence of acute hepatitis due to these viruses and rainfall or environmental temperature. Acute hepatitis due to enteric hepatitis viruses was seen throughout the year.

Adolescent↗

PubMed1999

Improved sensitivity of reverse transcriptase polymerase chain reaction for hepatitis C virus using random hexamer primers.

The use of specific primers and random primers for the detection of hepatitis C virus RNA by reverse transcriptase-polymerase chain reaction was compared. The cDNA obtained from using both methods was amplified by the same protocol. Of the 30 plasma specimens tested, 6 (20%) were hepatitis C virus RNA-positive using specific primers and 19 (63%) were positive using random primers, demonstrating that the use of random hexamer-primed reverse transcriptase-polymerase chain reaction significantly improves the sensitivity (p < 0.01).

DNA Primers↗

PubMed1999

Comparison of two different methodologies for the detection of hepatitis B virus DNA in plasma.

In this study, two different methodologies were compared for the detection of hepatitis B virus (HBV) DNA in the plasma of 28 patients and 36 controls. Method 1 was a nested polymerase chain reaction (PCR) followed by product detection in an ethidium bromide stained gel, whereas method II was a commercial single step PCR with digoxigenin labeled product captured by a probe and then detected in a digoxigenin-antidigoxigenin enzyme-linked immunosorbent assay (DIG ELISA). The results indicate that both methods are comparable showing a concordance of 98.4%, there was no statistically significant difference in the detection rates. We feel that any one of these assays may be suitable in a clinical laboratory setting, though the commercial assay may offer some advantages to laboratories without sufficient skilled staff in trouble-shooting PCR related problems.

DNA, Viral↗

PubMed1998

Unusual presentation during childhood of left ventricular myxoma.

Amongst all primary cardiac tumors, myxomas are the commonest, and their commonest site of origin is the left atrium. Myxomas originating in the left ventricle are rare. When seen, they usually present with a history of systemic embolisation and/or syncopal episodes, with constitutional symptoms being absent. We report here a child with left ventricular myxoma who presented with a prolonged febrile illness.

Aortic Valve↗

PubMed1998

Findings of colonoscopy in children: experience from Kuwait.

This report summarizes our retrospective analysis of 173 colonoscopic examinations performed on 159 children over a period of 9 years in Kuwait. Ninety-six children were males, with a male to female ratio of 1.5:1. The main indications for colonoscopy were rectal bleeding, polyps, and suspected inflammatory bowel disease. Examination was done under sedation or anaesthesia. One hundred and fifty-one (87 per cent) examinations were complete up to the caecum and 89 (51 per cent) up to the terminal ileum. The most common pathology was polyps in 42 children. All but one polyp were hamartomatous and mainly localized to the rectum and sigmoid colon. The majority had a single polyp. One child had adenomatous polyposis coli. One hundred and forty-two polyps were removed endoscopically with no complications. Inflammatory bowel disease was present in 34 (21 per cent) children (17 Crohn's disease, 11 ulcerative colitis, and 6 indeterminate colitis). Tuberculosis of the ileo-caecal region was diagnosed in two cases. Seven patients had rectal ulcers presenting as rectal bleeding. In 11 (7 per cent), the lesions were limited to the right side of the colon or terminal ileum. These results suggest that colonic pathology is not uncommon in children in Kuwait. The disease pattern is similar to that reported in western countries. As we have observed in adults, inflammatory bowel disease is seen in significant numbers among children in this region. In this survey we have observed a change in the disease frequency, Crohn's disease being more common that ulcerative colitis. Without adequate examination, the existence of inflammatory bowel disease and this possible changing pattern of disease would have gone unrecognized.

Adolescent↗

PubMed1997

Takayasu's arteritis: evaluation with three-dimensional time-of-flight MR angiography.

Three-dimensional time-of-flight MR angiography was performed in 16 patients with Takayasu's arteritis. Two regions were evaluated, the arch of aorta and its intrathoracic major branches, and the abdominal aorta with proximal portions of its major visceral and renal branches. Individual arteries and aortic segments, i. e. aortic arch and abdominal aorta, were evaluated for abnormalities such as stenosis, occlusion, dilatation and aneurysm formation. The results were compared with contrast angiography. Follow-up MR angiography was performed in three patients after 9-12 months. MR angiography demonstrated steno-occlusive lesions in all the patients and aneurysms in 2. In comparison with contrast angiography, good correlation was found in 129 of the 145 arteries and aortic segments. For the 12 false-positive results, incorrect slab placement and overestimation of stenosis were implicated. Interestingly, there were three false-negative results and one occlusion was underestimated as stenosis. A new lesion developed in 1 patient and one stenosis progressed in another patient upon follow-up. Three-dimensional time-of-flight MR angiography is a simple and fairly accurate method for documenting the lesions in Takayasu's arteritis and for its follow-up.

Adolescent↗

PubMed1997

Ulcerative colitis in Oman. A prospective study of the incidence and disease pattern from 1987 to 1994.

OBJECTIVE: Inflammatory bowel disease has been reported to have varying frequencies in different parts of the world, and there seem to be significant differences in the disease pattern and clinical course in cases of ulcerative colitis (UC). The aim of the present study was to assess the incidence and disease pattern of UC in Oman. METHOD: A prospective study, over a period of 8 years (1987-1994), was performed to study 108 patients found to have UC. RESULTS: The annual incidence of UC was 1.35/100,000. The disease was mainly seen in the middle and upper middle class group, and the majority were nonsmokers or exsmokers. There was no significant difference in the incidence of the disease between nationalities or sexes. Total colitis was seen in 18%, and a significant number had disease extending up to the splenic flexure. Proctitis was seen in 8%. Although, the extent of the disease was similar to reports from the West, these patients had fewer hospital admissions, blood transfusions and none of them suffered local complications such as toxic dilatation, perforation or severe bleeding. Sclerosing cholangitis occurred in 2 patients. Patients were followed up for a maximum period of up to 7 years after diagnosis and none developed dysplasia or cancer. Three patients had surgery mainly for failure of medical treatment. CONCLUSIONS: From this report it seems that UC occurs in Oman at a lower frequency compared to the West. Although, the extent of the disease was similar to Europeans, these patients had less severe disease with fewer complications.

Adolescent↗

PubMed1997

Absent conal septum in tetralogy of Fallot. An angiographic study.

Absent conal septum in tetralogy of Fallot (TF) is usually noted intraoperatively when the ventricular septal defect (VSD) is found abutting the pulmonary valve, its superior rim being nearly inaccessible transatrially, and the posterior rim being separated from the tricuspid valve (TV) by a muscular ridge. The authors retrospectively analyzed angiograms of 208 consecutive patients with TF seen at their center from July 1989 to December 1995 for absence of the conal septum and the presence of an interval between the TV and the margin of the VSD in 30 degrees right anterior oblique view. In 13 (6%) patients, angiograms were inadequate or of poor quality for assessment and were excluded. Twenty-two of the remaining 195 (11%) patients had a large muscular interval between the tricuspid annulus and the margin of the VSD, which was associated with an absent conal septum in 14 (7.2%) and a diminutive septum in 8 (4%) patients. Nine of the 14 patients with an absent conal septum at angiography underwent surgery, and this finding was confirmed in all. The authors conclude that absent conal septum is not uncommon in TF and constitutes an important variation in its anatomy that can be identified preoperatively at angiography for optimal surgical management.

Coronary Angiography↗

PubMed1997

Immediate and follow up results of Inoue balloon mitral valvotomy in juvenile rheumatic mitral stenosis.

BACKGROUND AND AIMS OF THE STUDY: Juvenile rheumatic mitral stenosis (MS) with severe pulmonary venous and arterial hypertension (PAH) is a relatively common occurrence in developing countries. The study objectives were to evaluate the safety, efficacy and follow up of Inoue balloon mitral valvotomy (IBMV) in juveniles with rheumatic MS. METHODS: A total of 193 patients with juvenile rheumatic MS were analyzed and compared with adults, with specific reference to the effect of IBMV on hemodynamics and pulmonary vasculature in patients with severe PAH. RESULTS: Mitral valve areas were smaller (0.76 +/- 0.22 versus 0.81 +/- 0.22 cm2), while mean pulmonary arterial pressure (MPAP) (44.5 +/- 16.5 versus 38.4 +/- 15.1 mmHg) and pulmonary vascular resistance (PVR) (5.5 +/- 4.6 versus 4.41 +/- 4.04 Wood units) were greater in juvenile patients when compared with adults. There was a 99% procedural success. Juvenile patients showed an overall greater fall in MPAP and PVR when compared with adults. The incidence of severe PAH was much higher (32%) among juveniles than adults (16%). Only 5% of patients with juvenile MS with severe PAH had residual severe PAH immediately after IBMV, compared with 17% in older patients. Hemodynamic benefits (echocardiographic mean transvalvular gradient and mitral valve area) were sustained at a mean follow up of 29 months, and there was no documented case of restenosis after successful IBMV. CONCLUSIONS: We conclude that IBMV is safe and effective in juvenile rheumatic MS and provides greater hemodynamic benefit compared with adults; such benefit is sustained during a mean follow up of 29 months.

Adolescent↗

PubMed1996

Transesophageal dobutamine-atropine stress echocardiography: diagnostic accuracy for coronary stenosis detection and localization.

Transesophageal echocardiography with dobutamine-atropine stress (TE-DASE) is a recently described technique for evaluation of coronary artery disease (CAD). We undertook this study prospectively to determine the feasibility, reliability and safety of this procedure in patients with known CAD and to evaluate its diagnostic accuracy for coronary stenoses of varying severity. Thirty-seven patients who underwent coronary arteriography (CART) and TE-DASE within a 3-month interval without intervening ischemic events or revascularisation were included in the study CART and stress echograms were independently evaluated by different observers. Stenosis was measured with calipers and a > or = 50% lumen diameter stenosis was considered significant. A reduction or lack of endocardial motion and/or wall thickening on progressive incremental stress was considered an abnormal response. TE-DASE could be successfully completed in 33/37 (90%) patients. Using a modified 16-segment model of the left ventricle (LV), 15.2 +/- 0.8 segments/patient and 501/528 (95%) segments overall could be optimally evaluated. Inter-observer concordance for an abnormal response was 94%. Predictive accuracies for one-vessel disease (1-VD), two-vessel disease (2-VD) and three-vessel disease (3-VD) were 88, 58 and 23% respectively. Overall sensitivity for detection of a significant (> or = 50%) stenosis was 72% (32% for moderate (50-69%), 90% for severe (> or = 70%) stenosis) and specificity was 96%. Diagnostic accuracy for localisation of significant stenosis was 95% for the left anterior descending artery (LAD), 86% for the left circumflex artery (LCX) and 88% for the right coronary artery (RCA). There were no major complications. We conclude that TE-DASE is a safe, reliable and easily-performed procedure and provides excellent visualisation of myocardial segments. Diagnostic accuracy for detection of severe stenosis and its localisation is excellent.

Atropine↗

PubMed1996

Importance of partitioning membranes of the brain and the influence of the neck in head injury modelling.

A head injury model consisting of the skull, the CSF, the brain and its partitioning membranes and the neck region is simulated by considering its near actual geometry. Three-dimensional finite-element analysis is carried out to investigate the influence of the partitioning membranes of the brain and the neck in head injury analysis through free-vibration analysis and transient analysis. In free-vibration analysis, the first five modal frequencies are calculated, and in transient analysis intracranial pressure and maximum shear stress in the brain are determined for a given occipital impact load.

Biomechanical Phenomena↗