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Biomedical subjects

N R Patel

Publications and source records attributed to N R Patel.

At least 19 recordsLinked to original sources
PubMed2002

What is the optimal electrode configuration for atrial defibrillators in man?

AIMS: To compare the atrial defibrillation threshold (DFT) for two electrode configurations in patients with drug refractory persistent atrial fibrillation (AF). METHODS AND RESULTS: 11 patients, 73% male, mean age 60.9 (range 38 to 83), underwent implantation of a Medtronic Jewel AF dual chamber defibrillator (model 7250). A step-up atrial DFT was performed in a randomized sequence for two electrode configurations: (1) Right atrial to distal coronary sinus electrode (RA > CS) and (2) defibrillator can to right ventricular and right atrial electrodes (CAN > RV + RA). The RA > CS configuration restored SR in 10 patients (91%). The CAN > RA + RV configuration restored SR in four patients (36%). The mean atrial DFT was significantly lower for the RA > CS than CAN > RA + RV configuration (10 +/- 7 Joules vs 25 +/- 6 Joules), P < 0.01. At 3 months post implantation, AF was reinduced and the protocol was repeated for the optimal electrode configuration. There was no significant difference in the atrial DFT compared with that at implant. CONCLUSION: The right atrium to coronary sinus electrode configuration significantly reduces the atrial DFT. The atrial DFT also remains stable at 3 months post-implantation. Patients with persistent AF undergoing insertion of an atrial defibrillator should have a coronary sinus electrode implanted.

Adult↗
PubMed2001

Modified Norwood operation for hypoplastic left heart syndrome.

BACKGROUND: We examined early results in infants with hypoplastic left heart syndrome undergoing the Norwood operation with perioperative use of inhaled nitric oxide and application of extracorporeal membrane oxygenation. METHODS: Medical records were reviewed retrospectively. RESULTS: Between April 1997 and March 2001, 50 infants underwent a modified Norwood operation for hypoplastic left heart syndrome. Mean age at operation was 7.5 +/- 5.7 days, and mean weight was 3.1 +/- 0.5 kg. Five infants had a delayed operation because of sepsis. The mean diameter of the ascending aorta by echocardiography was 3.6 +/- 1.8 mm. Ductal cannulation was used to establish cardiopulmonary bypass in all patients. Mean circulatory arrest time was 39.4 +/- 4.8 minutes. The size of the pulmonary-systemic shunt was 3.0 mm in 6 infants, 3.5 mm in 37, and 4.0 mm in 7. Infants with persistent hypoxia (partial pressure of oxygen < 30 mm Hg) received nitric oxide after they were weaned from cardiopulmonary bypass. Extracorporeal membrane oxygenation was initiated in 8 infants in the pediatric intensive care unit primarily for low cardiac output and in 8 in the operating room because of the inability to separate them from cardiopulmonary bypass. The 30-day mortality rate was 22% (11 of 50 patients), and the hospital mortality rate was 32% (16 of 50 patients). Mean follow-up was 17 months. Ten patients (20%) underwent stage-two repair, with one operative death. One survivor had a Fontan procedure, and 2 underwent heart transplantation, with one death. CONCLUSIONS: Early application of extracorporeal membrane oxygenation for hemodynamic instability and selective use of nitric oxide for persistent hypoxia in the immediate postoperative period may improve survival of patients with hypoplastic left heart syndrome. Renal failure requiring hemofiltration during extracorporeal membrane oxygenation (p < 0.05) and cardiopulmonary arrest in the pediatric intensive care unit (p < 0.05) were predictors of hospital mortality.

Administration, Inhalation↗
PubMed2001

Safety, effectiveness and cost efficacy of diagnostic electrophysiology and radiofrequency ablation in a district general hospital.

Electrophysiological studies (EPS) are now being performed in district general hospitals (DGH) in the UK. In order to audit our results, a prospective database was established for all patients undergoing EPS and radiofrequency (RF) ablation at Eastbourne District General Hospital, East Sussex. Between 1 January 1997 and 1 July 2000, 300 EPS procedures were performed, resulting in 155 RF ablations. The average RF ablation procedure time was 119.3 minutes with an average fluoroscopy time of 19.1 minutes. Cost per RF ablation procedure was 1166.79 Pounds excluding use of facilities, pacemaker devices, medical nursing and radiography staffing costs. The overall success rate for RF ablation was 93.6% with a major complication rate of 0.6%, a total complication rate of 3.9% and no associated mortality. We have shown that RF ablation can be performed safely, effectively and economically in a DGH setting with a high rate of success and a low complication rate.

Adult↗
PubMed2000

How many people with heart failure are appropriate for biventricular resynchronization?

AIMS: Increasing evidence exists suggesting that biventricular pacing improves outcome and symptoms in severe heart failure if various selection criteria are fulfilled. It is unsure how many people might benefit from this therapy. Our aim was to provide such data. METHODS AND RESULTS: Over one calendar year all patients admitted to a large U.K. District General Hospital, that were classified with a diagnosis of heart failure, were audited. The selection criteria were; (1) severe heart failure (NYHA class III or IV), (2) heart failure due to a dilated cardiomyopathy, (3) QRS duration greater than 120 ms or (4) the presence of a bundle branch block pattern. Subjects were divided into those in sinus rhythm to determine those who would be suitable for atrially synchronized biventricular pacing and those with an abnormally long PR interval (>210 ms) who might additionally benefit from improved atrioventricular synchrony. 1042 patients were coded with heart failure. 721 fulfilled diagnostic criteria and were studied. 202 (28%) had severe heart failure, 178 (25%) had a QRS of at least 120 ms, 437 (61%) had an ischaemic cardiomyopathy, 176 (24%) an idiopathic cardiomyopathy and 433 (60%) were in sinus rhythm. Overall mortality at the time of census was 29%. 43 patients were suitable for biventricular pacing with a further 29 atrial patients fibrillation who might benefit from biventricular pacing alone. CONCLUSION: Using our criteria, approximately 10% of an unselected group of heart failure admitted to a typical U.K. district general hospital over a calendar year would be appropriate for biventricular pacing. This represents a large number of patients who might derive benefit from this new therapy.

Aged↗
PubMed2000

The pharmacologic mechanism by which inhaled epinephrine reduces airway obstruction in respiratory syncytial virus-associated bronchiolitis.

Inhaled racemic epinephrine relieves airway obstruction in patients with respiratory syncytial virus bronchiolitis. The contribution of alpha- versus beta-adrenoreceptor stimulation toward this clinical effect is unknown. We describe an infant treated with propranolol for supraventricular tachycardia in whom respiratory syncytial virus bronchiolitis developed. Inhaled racemic epinephrine improved his respiratory symptoms, whereas nebulized albuterol did not.

Administration, Inhalation↗
PubMed2000

Does angina vary with the menstrual cycle in women with premenopausal coronary artery disease?

OBJECTIVE: To determine whether angina in women with established coronary heart disease varies with changes in hormone concentrations during the menstrual cycle. DESIGN: Subjects were prospectively studied once a week for four weeks. SETTING: Cardiology outpatient department of tertiary referral centre. SUBJECTS: Nine premenopausal women, mean (SEM) age 38.89 (2.18) years, with established coronary heart disease, symptomatic angina, and a positive exercise test. MAIN OUTCOME MEASURE: Myocardial ischaemia as determined by time to 1 mm ST depression during symptom limited exercise testing. Position in the menstrual cycle was established from hormone concentrations. RESULTS: The early follicular phase, when oestradiol and progesterone concentrations were both low, was associated with the worst exercise performance in terms of time to onset of myocardial ischaemia, at 290 (79) seconds; the best performance (418 (71) seconds) was when oestrogen concentrations were highest in the mid-cycle (p < 0.05). Similar trends were observed in other measured variables. Progesterone concentrations did not influence exercise performance. CONCLUSIONS: During the menstrual cycle myocardial ischaemia was more easily induced when oestrogen concentrations were low. This may be important for timing the assessment and evaluating treatment in women with coronary heart disease.

Adult↗
PubMed1999

Effect of inhaled nitric oxide on respiratory mechanics in ventilated infants with RSV bronchiolitis.

OBJECTIVE: To evaluate the bronchodilator effect of inhaled nitric oxide (NO) in infants with respiratory failure caused by respiratory syncytial virus (RSV) bronchiolitis and to compare the effect with the one obtained by salbutamol. DESIGN: Prospective study. SETTING: Pediatric intensive care unit of a university children's hospital. PATIENTS: Twelve acutely ill, intubated infants (mean age 4.5 months, mean weight 4.9 kg) with respiratory failure due to documented RSV bronchiolitis. INTERVENTIONS: Total respiratory system resistance (Rrs) was measured by single breath occlusion at the baseline and after inhaling NO at 20, 40 and 60 ppm for 1 h, and after inhalation of a standard beta2-agonist, salbutamol. Arterial blood gas analysis was performed at each study level on 6 of the 12 patients. RESULTS: The baseline mean Rrs (SE) was 0.29 (0.04) cm H2O/ml per s. At each dose of NO, the mean Rrs (SE) was 0.28 (0.04) cm H2O/ml per s. With salbutamol, the mean Rrs (SE) was 0.21 (0.03) cm H20/ml per s. These values were not significantly different from each other (by ANOVA). Inhaled NO produced a significant decrease in Rrs of greater than 4 times the coefficient of variation of the baseline measurement in 3 of 12 patients. Seven of 12 patients had no significant change while two patients had a significant increase in Rrs. Inhaled salbutamol produced a significant decrease in Rrs in 5 of 11 patients, while 6 showed no change in Rrs. CONCLUSION: Inhaled NO has no apparent bronchodilator effect in the majority of acutely ill infants with RSV bronchiolitis and does not appear to provide any additional benefit over the use of salbutamol. The clinical benefit of inhaled NO as a bronchodilator is questionable under these conditions.

Administration, Inhalation↗
PubMed1996

Prevalence of gastroesophageal reflux in patients who develop pneumonia following percutaneous endoscopic gastrostomy: a 24-hour pH monitoring study.

Percutaneous endoscopic placement of feeding gastrostomies (PEG) was pioneered by Gauderer et. al. in 1980 [1]. Since then, it has become the preferred method of providing enteral nutritional support in children and adults because of advantages in morbidity and cost [2,3]. Pneumonia is a known sequel of this procedure, occurring at different rates, depending on the length of follow-up. Some series have shown an incidence of 10% at 30 days and others 56% at 11 months [4,5]. It does not appear that PEG feeding offers an advantage over the more traditional naso-enteric tube feeding methods in this respect. To study the prevalence of gastroesophageal reflux (GER) in PEG-fed patients, we quantitated GER by 24-hour intraesophageal pH monitoring in a group of patients who developed post-PEG pneumonia and compared it with a control group. Our study demonstrates an increased prevalence of GER in the pneumonia group compared with the control group. However, the exact contribution of this observed increased GER to the development of pneumonia needs to be determined.

Adult↗
PubMed1996

A newly developed PCR assay of H. pylori in gastric biopsy, saliva, and feces. Evidence of high prevalence of H. pylori in saliva supports oral transmission.

We have recently developed a new PCR assay for the detection of H. pylori. In this study, the polymerase chain reaction (PCR) assay was used to detect H. pylori in 88 gastric biopsy, 85 saliva, and 71 fecal specimens from 88 patients. H. pylori infection was confirmed in 71 of 88 patients by culture and/or histological stain of gastric biopsies. Serum IgG antibody to H. pylori was also measured and resulted in 97% sensitivity and 94% specificity. H. pylori DNA was detected by the PCR assay in gastric biopsy specimens from all 71 patients (100% sensitivity) with proven gastric H. pylori infection but not from 17 noninfected patients (100% specificity). In saliva specimens, H. pylori DNA was identified in 57 of the 68 patients (84%) with proven gastric H. pylori infection and in three of the 17 patients without gastric H. pylori infection. However, the PCR assay was only able to detect H. pylori DNA in the feces from 15 of 61 patients (25%) with proven gastric H. pylori infection and one of the 10 patients without gastric H. pylori infection. The results show that the PCR assay is reliable for detecting the presence of H. pylori in gastric biopsy and saliva specimens. The data indicate that H. pylori exists in a higher prevalence in saliva than feces and that the fecal-oral route may be an important means of transmission of this infection in developing countries but not as significant as previously suspected in the developed countries. It is likely that the oral-oral route is more prominent.

Antibodies, Bacterial↗
PubMed1995

Exact logistic regression: theory and examples.

We provide an alternative to the maximum likelihood method for making inferences about the parameters of the logistic regression model. The method is based appropriate permutational distributions of sufficient statistics. It is useful for analysing small or unbalanced binary data with covariates. It also applies to small-sample clustered binary data. We illustrate the method by analysing several biomedical data sets.

Algorithms↗
PubMed1995

Oral absorption of anti-AIDS nucleoside analogues. 1. Intestinal transport of didanosine in rat and rabbit preparations.

The intestinal transport of didanosine (ddl), a nucleoside analog used in the treatment of human immunodeficiency virus (HIV) infection, was characterized using in situ and in vitro techniques. The zero-trans uptake of ddl in rat intestinal brush border membrane vesicles (BBMV) was linear over the range of 1 microM to 50 mM, ruling out a significant carrier-mediated absorption component. The lack of carrier-mediated transport was confirmed in a second species (rabbit). In order to quantitate the convective (Pconv) and diffusive (Pdiff) components of ddl intestinal permeability, the steady state wall permeability (P*w) was determined using an established perfusion technique in rats. Even though baseline P*w (pH 6.5, 290 mosm/kg, no modulator) and fluid absorption results were similar to those of furosemide, the ratios (ddl:furosemide) of Pdiff and phi, the sieving coefficient, were 0.31:1 and 1.70:1, respectively, demonstrating that ddl's Pdiff is low and Pconv is high relative to furosemide's, suggesting significant paracellular absorption of ddl. The apparent diffusive absorptive clearances (P'app) of ddl and furosemide were determined in BBMV, which lack functional tight junctions, and the ratios (ddl:furosemide) of P'app in rat and rabbit were 0.23:1 and 0.24:1, respectively. The BBMV results demonstrate that the majority of ddl intestinal transport does not occur by passive membrane diffusion, confirming the single pass intestinal perfusion (SPIP) findings. The results of these studies suggest that ddl is transported by nonfacilitated membrane and paracellular diffusion with paracellular transport being responsible for the majority of ddl absorption from the intestine.

Animals↗
PubMed1995

High prevalence of Helicobacter pylori in saliva demonstrated by a novel PCR assay.

AIMS: To investigate the prevalence of Helicobacter pylori in the saliva of patients infected with this bacterium. METHODS: A novel polymerase chain reaction (PCR) assay was developed to detect H pylori in saliva and gastric biopsy specimens from patients undergoing endoscopy. RESULTS: Our PCR assay amplified a 417 base pair fragment of DNA from all 21 DNAs derived from H pylori clinical isolates but did not amplify DNA from 23 non-H pylori strains. Sixty three frozen gastric biopsy and 56 saliva specimens were tested. H pylori specific DNA was detected by PCR in all 39 culture positive biopsy specimens and was also identified from another seven biopsy specimens which were negative by culture but positive by histology. H pylori specific DNA was identified by PCR in saliva specimens from 30 (75%) of 40 patients with H pylori infection demonstrated by culture or histological examination, or both, and in three patients without H pylori infection in the stomach. CONCLUSION: The results indicate that the oral cavity harbours H pylori and may be the source of infection and transmission.

Base Sequence↗
PubMed1994

Gastrointestinal and biliary indwelling devices.

Esophageal and biliary stents are indwelling devices used in the treatment of selected gastrointestinal and biliary disorders. Stenting is accepted as a standard procedure for palliation of malignant obstruction of the esophagus and biliary system. Review of the early and late complications associated with these devices is made with emphasis on the clinical and radiographic features. A suggested approach to diagnosis and treatment recommendations are made for each complication that the emergency department physician may encounter.

Biliary Tract↗
PubMed1993

Isolation of Helicobacter pylori from saliva.

Helicobacter pylori was grown in low numbers from the saliva of one of nine patients who were positive for gastric H. pylori. The saliva-derived isolate from this patient was identical to the antral biopsy-derived isolate from the same patient and differed from isolates cultured from the antral biopsies of all other patients by soluble-protein electrophoresis, restriction endonuclease DNA analysis, and Southern blot hybridization. This is the first observation, to our knowledge, of the recovery of viable H. pylori from saliva.

Fatty Acids↗