Fetal Electrocardiogram Extraction and Analysis Using Adaptive Noise Cancellation and Wavelet Transformation Techniques

Birth defect-related demise is mainly due to congenital heart defects. In the earlier stage of pregnancy, fetus problem can be identified by finding information about the fetus to avoid stillbirths. The gold standard used to monitor the health status of the fetus is by Cardiotachography(CTG), cannot be used for long durations and continuous monitoring. There is a need for continuous and long duration monitoring of fetal ECG signals to study the progressive health status of the fetus using portable devices. The non-invasive method of electrocardiogram recording is one of the best method used to diagnose fetal cardiac problem rather than the invasive methods.The monitoring of the fECG requires development of a miniaturized hardware and a efficient signal processing algorithms to extract the fECG embedded in the mother ECG. The paper discusses a prototype hardware developed to monitor and record the raw mother ECG signal containing the fECG and a signal processing algorithm to extract the fetal Electro Cardiogram signal. We have proposed two methods of signal processing, first is based on the Least Mean Square (LMS) Adaptive Noise Cancellation technique and the other method is based on the Wavelet Transformation technique. A prototype hardware was designed and developed to acquire the raw ECG signal containing the mother and fetal ECG and the signal processing techniques were used to eliminate the noises and extract the fetal ECG and the fetal Heart Rate Variability was studied. Both the methods were evaluated with the signal acquired from a fetal ECG simulator, from the Physionet database and that acquired from the subject. Both the methods are evaluated by finding heart rate and its variability, amplitude spectrum and mean value of extracted fetal ECG. Also the accuracy, sensitivity and positive predictive value are also determined for fetal QRS detection technique. In this paper adaptive filtering technique uses Sign-sign LMS algorithm and wavelet techniques with Daubechies wavelet, employed along with de noising techniques for the extraction of fetal Electrocardiogram.Both the methods are having good sensitivity and accuracy. In adaptive method the sensitivity is 96.83, accuracy 89.87, wavelet sensitivity is 95.97 and accuracy is 88.5. Additionally, time domain parameters from the plot of heart rate variability of mother and fetus are analyzed.     

Acute severe asthma

Acute exacerbations of asthma are very common reasons for a presentation to emergency departments. This paper focuses on defining the high‐risk group, consideration of the concept of phenotypes of acute asthma, the assessment of severe and life‐threatening exacerbations and an emphasis on the management of the more severe end of the exacerbation severity. A number of evidence‐based guidelines exist throughout the world and are all slightly different. This reflects the poor evidence base for some of those recommendations. Thus, a large variation of treatment drugs, doses and regimen are used and clearly not standardised. This paper aims to present a summary of the best evidence and discuss some of these controversies. The most important aspect of treating an exacerbation of acute asthma is to review regularly and assess response to treatment. Severe and life‐threatening episodes should be treated with early use of intravenous treatment in a stepwise manner following the local guidelines. Non‐invasive ventilation and high flow nasal cannulae delivery of oxygen in the emergency department are evolving modalities, but evidence for their use is currently limited.     

Retrospective evaluation of the conversion of amlodipine to alternative calcium channel blockers

STUDY OBJECTIVE: To evaluate the effectiveness, safety, and costs associated with a formulary conversion from amlodipine to alternative calcium channel blockers. DESIGN: Retrospective study. SETTING: Veterans Affairs Medical Center. PATIENTS: One hundred patients with hypertension who were receiving amlodipine. INTERVENTION: Data from a random sample of 100 patients who were taking amlodipine and converted to a formulary calcium channel blocker from February 1, 1999-October 30, 1999, were entered into an Excel database for evaluation of the conversion. MEASUREMENTS AND MAIN RESULTS: Patients were required to have a diagnosis of hypertension and have had two consecutive clinic visits with blood pressure measurements (and no changes in antihypertensive therapy) before conversion. End points were changes in average systolic blood pressure, diastolic blood pressure, and mean arterial pressure (MAP) from the two clinic visits before and after conversion. In addition, data were collected and analyzed with regard to adverse drug reactions, average dosage of the alternative calcium channel blocker, number of additional antihypertensives begun or discontinued, and number of dosage changes in antihypertensives within the two visits after conversion, and the overall cost impact of conversion. Average systolic blood pressure was reduced from 141.6 +/- 15.1 to 139.2 +/- 15.3 mm Hg after the conversion (NS). Average diastolic blood pressure was significantly reduced from 74 +/- 9.5 to 72.6 +/- 10.1 mm Hg after conversion (p=0.032), as was MAP (97.0 +/-q 9.3 to 94.8 +/- 10.0 mm Hg, p=0.026). Five patients had other changes in therapy made concurrently at the time of conversion, and 19 had changes after conversion. When these patients were excluded from analysis, the reduction in systolic blood pressure after conversion was significant (141.4 +/- 14.5 to 137.7 +/- 14.3 mm Hg, p=0.022), as were reductions in diastolic blood pressure (74.4 +/- 9.4 to 71.7 +/- 9.8 mm Hg, p=0.014) and MAP (96.7 +/- 9.1 to 93.7 +/- 9.3 mm Hg, p=0.007). Of patients who had postconversion changes in therapy, 8 (42%) were converted to diltiazem ER, nifedipine CC, or doses of felodipine that were 50% of the original dose of amlodipine. The overall cost impact of the conversion was a net savings of $14,858/year for each 100 patients converted. CONCLUSION: Conversion from amlodipine to other calcium channel blockers resulted in statistically significant reductions in diastolic blood pressure and MAP, and was safe as well as cost-effective. Conversion to calcium channel antagonists other than felodipine or less than equal dosages of felodipine may require dosage titration. When converting patients from amlodipine, dosages usually should be equal to those of felodipine; if converting to other calcium channel antagonists, the need for adjustments should be anticipated.     

Alloimmunization Against Well Defined Polymorphic Major Histocompatibility or Class I MHC Transfected L Cells Antigens Can Prevent Poly IC Induced Fetal Death in Mice

METHOD : It is possible to induce increased fetal resorption in a number of inbred murine matings by injecting Poly (I) Poly (C12U) 3.5 days postconception, a maneuver associated with natural killer-mediated damage to the feto placental unit such as occurs in spontaneous fetal resorptions. RESULTS : We show here that alloimmunization can block this effect. In addition, maternal immune responses induced by alloimmunization against isolated mutant class I or class II, as well as by immunization with class I MHC alloantigens (K^d) transfected L cells are sufficient to restore normal fetal viability. It is not necessary that the maternal immune response be specifically directed against paternal alloantigens fr the fetal protecton to ensue, since the effect occurs in inbred matings when the mother is immunized against unrelated class I or class II alloantigens. As in previous studies conducted in the murine species, not all MHC alloimmunizations are protective. In addition, as control, immunization with a monomorphic class I MHC molecular (37), transfected L cells, sheep red blood cells or hen egg lysozyme is without effect. CONCLUSION : These results indicate that defined MHC antigens can mediate fetal protection from induced fetal resorption, and suggest that one driving force in promoting MHC antigen polymorphism in mammals is their capacity to confer protection from NK mediated fetal demise.     

Metformin monitoring and change in serum creatinine levels in patients undergoing radiologic procedures involving administration of intravenous contrast media

STUDY OBJECTIVES: To evaluate the prevalence and magnitude of serum creatinine level elevations in patients receiving metformin who underwent radiologic procedures involving administration of intravenous contrast media, and to evaluate the efficacy of an electronic consultation in promoting timely evaluation of renal function after the procedure. DESIGN: Retrospective evaluation. SETTING: Veterans Affairs Medical Center. PATIENTS: Ninety-seven patients receiving metformin who underwent a radiologic procedure involving administration of intravenous contrast media over a 27-month period. MEASUREMENTS AND MAIN RESULTS: Ninety-seven patients underwent a total of 111 radiologic procedures with documented administration of intravenous contrast dye. Average time from procedure to laboratory follow-up, excluding one patient, was 2.62+/-1.56 days. Average serum creatinine levels before and after the procedure were 1.10+/-0.19 and 1.13+/-0.23 mg/dl, respectively (p>0.05). Four patients developed contrast material-associated nephropathy. An additional four patients with borderline serum creatinine levels at baseline (1.4 mg/dl) had a serum creatinine level of 1.5 mg/dl or greater after the procedure. CONCLUSION: Our results indicated that electronic consultations result in timely evaluation of serum creatinine levels in patients receiving metformin who undergo a radiologic procedure involving intravenous contrast material. Also, the study suggests that nearly 4% of patients with diabetes mellitus and normal renal function may develop contrast material-associated nephropathy [corrected] with nonionic contrast material. In addition, about 8% of patients with diabetes treated with metformin (with baseline serum creatinine levels < 1.5 mg/dl) who undergo a procedure with nonionic intravenous contrast material acquire an increased risk (serum creatinine > or = 1.5 mg/dl) of lactic acidosis. These findings support the recommendations of the Food and Drug Administration regarding metformin monitoring in patients undergoing radiologic procedures involving administration of intravenous contrast media.     

The Role of Catheter Ablation Techniques in the Treatment of Classic (Type 1) Atrial Flutter

Several attempts at circuit interruption of type 1 atrial flutter by means of surgical or catheter techniques have been published. We recently reported the results of a series of patients who underwent catheter fulguration of the low septal right atrium, with a mean follow-up of almost 3 years. True electrophysiological success was observed in 7/14 patients (50%). Clinical success, defined as absence of symptoms, was observed in 8/14 (57%) in this patient population. No serious complications were encountered, but the potential risks of DC shock, and the experience that we gained in right atrial mapping using this approach, led us to reconsider the role of atrial DC ablation in these patients. Additional studies assessing the meaning of fragmented electrograms, and identification of one for of severall slow conduction areas of the reentrant circuit are ongoing.     

Toxic oxygen metabolites induce vasoconstriction and bronchoconstriction in isolated, plasma-perfused rat lungs

Effects of toxic oxygen metabolites (TOM) on the pulmonary vascular bed and airways were studied in isolated, plasma-perfused rat lungs. TOM were generated by xanthine oxidase (XO) (0.1 or 0.25 unit.ml-1) and hypoxanthine (HX) (1 mol.l-1). In vitro measurements by chemiluminescence indicated that the major oxygen metabolite generated by XO and HX was H2O2. Measurements of PO2 in the perfusate as an indicator of O2-consumption suggested that production of TOM by XO and HX was finished within 30 min. XO and HX induced an early dose-dependent bronchoconstriction and a late increase in transpulmonary pressure (Ptp). Pulmonary arterial pressure (Ppa) increased gradually and levelled off within 30 min with low-dose XO, but not with high-dose XO. As judged by weight increase of the lungs, interstitial edema occurred regularly. Allopurinol, an inhibitor of XO, blocked the lung responses caused by XO and HX. Catalase attenuated all lung responses induced by XO and HX, while superoxide dismutase had no effect. The hydroxyl radical scavenger dimethylsulfoxide abolished the increase in Ptp and attenuated the increase in Ppa, but did not consistently protect the lungs from edema development. This study shows that TOM induce vasoconstriction, bronchoconstriction and lung edema in plasma-perfused rat lungs, mainly due to generation of H2O2 and the hydroxyl radical.     

Atrial Septal Versus Atrial Appendage Pacing:

HERMIDA, J.-S., et al. : Atrial Septal Versus Atrial Appendage Pacing: Feasibility and Effects on Atrial Conduction, Interatrial Synchronization, and Atrioventricular Sequence. Atrial septal (Se-P) and atrial appendage pacing (Ap-P) were compared in a randomized, controlled study to assess the feasibility, the reliability, and the effects of Se-P on atrial conduction, interatrial synchronization, and the AV sequence. The main baseline characteristics of the patients were comparable in both groups. There was no difference in feasibility or reliability between the two techniques. Compared to Ap-P   (n = 28)   , Se-P   (n = 28)   decreased the P wave duration, left atrial electromechanical delay (LAEMD), and interatrial interval (−1.6% vs   +28%, P < 0.001; −3%   vs   + 30%, P < 0.001; −130%   vs   + 78%, P < 0.001   ); it induced a smaller increase of the right AEMD, a slight reversal of the timing of the atrial systoles and a shortening of the PR interval (−13% vs   + 25%, P < 0.001   ) and of the interval separating atrial systoles from ventricular activation. Finally, the shortening of the PR interval was smaller during high Se-P versus low Se-P. Se-P avoids the undesirable prolongation of the atrial, interatrial, and AV conductions observed during Ap-P. In addition, Se-P creates a slight reversal of the timing of the atrial systoles and induces a shortening of PR interval, the extent of which could depend on the height of the pacing site on the septum. (PACE 2003; 26[Pt. I]:26–35)