Displaying publications 81 - 100 of 209 in total

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  1. Najafabadi FS, Zahedi E, Mohd Ali MA
    Comput Biol Med, 2006 Mar;36(3):241-52.
    PMID: 16446158
    In this paper, an algorithm based on independent component analysis (ICA) for extracting the fetal heart rate (FHR) from maternal abdominal electrodes is presented. Three abdominal ECG channels are used to extract the FHR in three steps: first preprocessing procedures such as DC cancellation and low-pass filtering are applied to remove noise. Then the algorithm for multiple unknown source extraction (AMUSE) algorithm is fed to extract the sources from the observation signals include fetal ECG (FECG). Finally, FHR is extracted from FECG. The method is shown to be capable of completely revealing FECG R-peaks from observation leads even with a SNR=-200dB using semi-synthetic data.
    Matched MeSH terms: Electrocardiography
  2. Mahri N, Gan KB, Meswari R, Jaafar MH, Mohd Ali MA
    J Med Eng Technol, 2017 May;41(4):298-308.
    PMID: 28351231 DOI: 10.1080/03091902.2017.1299229
    Myocardial infarction (MI) is a common disease that causes morbidity and mortality. The current tools for diagnosing this disease are improving, but still have some limitations. This study utilised the second derivative of photoplethysmography (SDPPG) features to distinguish MI patients from healthy control subjects. The features include amplitude-derived SDPPG features (pulse height, ratio, jerk) and interval-derived SDPPG features (intervals and relative crest time (RCT)). We evaluated 32 MI patients at Pusat Perubatan Universiti Kebangsaan Malaysia and 32 control subjects (all ages 37-87 years). Statistical analysis revealed that the mean amplitude-derived SDPPG features were higher in MI patients than in control subjects. In contrast, the mean interval-derived SDPPG features were lower in MI patients than in the controls. The classifier model of binary logistic regression (Model 7), showed that the combination of SDPPG features that include the pulse height (d-wave), the intervals of "ab", "ad", "bc", "bd", and "be", and the RCT of "ad/aa" could be used to classify MI patients with 90.6% accuracy, 93.9% sensitivity and 87.5% specificity at a cut-off value of 0.5 compared with the single features model.
    Matched MeSH terms: Electrocardiography
  3. Borhanuddin BK, Abdul Latiff H, Mohamed Yusof AK
    Cardiol Young, 2022 Dec;32(12):1994-1998.
    PMID: 35707919 DOI: 10.1017/S1047951122000154
    BACKGROUND: CT is an accepted non-invasive imaging tool to assess the coronary arteries in adults; however, its utilisation in children is limited by high heart rate and lack of standardised protocol. We sought to assess diagnostic quality and factors that affect image quality of CT in assessing coronary artery lesions in Kawasaki patients less than 18 years of age.

    METHODOLOGY: CT coronary angiography was performed on patients with Kawasaki disease diagnosed with coronary aneurysm or suspected to have coronary stenosis. Studies were performed using electrocardiogram-gated protocols. General anaesthesia was used in patients who were not cooperative for breathing control. Heart rate, image quality, and effective radiation dose were documented.

    RESULTS: Fifty-two Kawasaki patients underwent CT coronary angiography to assess coronary artery lesions. Median heart rate was 88 beats per minute (range 50-165 beats/minute). Image quality was graded as excellent in 34 (65%) patients, good in 17 (32%), satisfactory in 1, and poor in 1 patient. Coronary artery aneurysm was found in 25 (bilateral = 6, unilateral = 19, multiple = 11). Thrombus was found in 11 patients resulting in partial and total occlusion in 8 and 3 patients, respectively. Coronary stenosis was noted in 2 patients. The effective radiation dose was 1.296 millisievert (median 0.81 millisievert). Better diagnostic imaging quality was significantly related to lower heart rate (p = 0.007).

    CONCLUSION: Electrocardiogram-triggered CT coronary angiography provides a good diagnostic assessment of coronary artery lesions in children with Kawasaki disease.

    Matched MeSH terms: Electrocardiography/methods
  4. Loh KY, Mohamed AL
    N Engl J Med, 2005 Sep 1;353(9):933.
    PMID: 16135838 DOI: 10.1056/NEJMicm040398
    Matched MeSH terms: Electrocardiography*
  5. Noor Zurani Md Haris Robson, Mohamad Hussain Habil
    ASEAN Journal of Psychiatry, 2010;11(1):103-107.
    MyJurnal
    Objective: This case report highlights the risk of Torsade de Pointes (TdP), a life threatening cardiac arrhythmia in a heroin dependent patient receiving methadone substitution therapy who was prescribed erythromycin for upper respiratory tract infection. Method: We report a case of a 35-year-old Malay man on methadone maintenance treatment who developed TdP possibly due to drug interaction between methadone and erythromycin. Results: The
    patient reported feeling unwell, chest pain and feeling dizzy after consuming 2 doses of erythromycin. ECG monitoring showed prolonged rate-corrected QT interval leading to TdP. The patient was admitted to the ward where the cardiac arrhythmia ceased following methadone discontinuation. This cardiac arrhythmia was most likely due to drug interaction between methadone and erythromycin (an enzyme inhibitor) which led to an increase in methadone concentration and potentiated the adverse effects. Conclusion: As methadone is a beneficial treatment for heroin dependent patients, the risk of cardiac arrhythmia is of great concern. To avoid complications of drug interaction, patients on methadone therapy should be advised to seek medical assessment before taking other drugs. As TdP is life threatening, it is thus important that physicians and psychiatrists involved in the treatment of
    heroin dependent patients on methadone substitution therapy be made aware of this risk.
    Matched MeSH terms: Electrocardiography
  6. Moein S
    Adv Exp Med Biol, 2010;680:109-16.
    PMID: 20865492 DOI: 10.1007/978-1-4419-5913-3_13
    In this paper, application of Artificial Neural Network (ANN) for electrocardiogram (ECG) signal noise removal has been investigated. First, 100 number of ECG signals are selected from Physikalisch-Technische Bundesanstalt (PTB) database and Kalman filter is applied to remove their low pass noise. Then a suitable dataset based on denoised ECG signal is configured and used to a Multilayer Perceptron (MLP) neural network to be trained. Finally, results and experiences are discussed and the effect of changing different parameters for MLP training is shown.
    Matched MeSH terms: Electrocardiography/statistics & numerical data*
  7. Al-Busaidi AM, Khriji L, Touati F, Rasid MF, Mnaouer AB
    J Med Syst, 2017 Sep 12;41(10):166.
    PMID: 28900815 DOI: 10.1007/s10916-017-0817-1
    One of the major issues in time-critical medical applications using wireless technology is the size of the payload packet, which is generally designed to be very small to improve the transmission process. Using small packets to transmit continuous ECG data is still costly. Thus, data compression is commonly used to reduce the huge amount of ECG data transmitted through telecardiology devices. In this paper, a new ECG compression scheme is introduced to ensure that the compressed ECG segments fit into the available limited payload packets, while maintaining a fixed CR to preserve the diagnostic information. The scheme automatically divides the ECG block into segments, while maintaining other compression parameters fixed. This scheme adopts discrete wavelet transform (DWT) method to decompose the ECG data, bit-field preserving (BFP) method to preserve the quality of the DWT coefficients, and a modified running-length encoding (RLE) scheme to encode the coefficients. The proposed dynamic compression scheme showed promising results with a percentage packet reduction (PR) of about 85.39% at low percentage root-mean square difference (PRD) values, less than 1%. ECG records from MIT-BIH Arrhythmia Database were used to test the proposed method. The simulation results showed promising performance that satisfies the needs of portable telecardiology systems, like the limited payload size and low power consumption.
    Matched MeSH terms: Electrocardiography*
  8. Khor KH, Shiels IA, Campbell FE, Greer RM, Rose A, Mills PC
    Vet J, 2014 Feb;199(2):229-35.
    PMID: 24321367 DOI: 10.1016/j.tvjl.2013.11.006
    Analysis of heart rate (HR) and heart rate variability (HRV) are powerful tools to investigate cardiac diseases, but current methods, including 24-h Holter monitoring, can be cumbersome and may be compromised by movement artefact. A commercially available data capture and analysis system was used in anaesthetised healthy cats to measure HR and HRV during pharmacological manipulation of HR. Seven healthy cats were subjected to a randomised crossover study design with a 7 day washout period between two treatment groups, placebo and atenolol (1mg/kg, IV), with the efficacy of atenolol to inhibit β1 adrenoreceptors challenged by epinephrine. Statistical significance for the epinephrine challenge was set at P<0.0027 (Holm-Bonferroni correction), whereas a level of significance of P<0.05 was set for other variables. Analysis of the continuous electrocardiography (ECG) recordings showed that epinephrine challenge increased HR in the placebo group (P=0.0003) but not in the atenolol group. The change in HR was greater in the placebo group than in the atenolol group (P=0.0004). Therefore, compared to cats pre-treated with placebo, pre-treatment with atenolol significantly antagonised the tachycardia while not significantly affecting HRV. The increased HR in the placebo group following epinephrine challenge was consistent with a shift of the sympathovagal balance towards a predominantly sympathetic tone. However, the small (but not significant at the critical value) decrease in the normalised high-frequency component (HFnorm) in both groups of cats suggested that epinephrine induced a parasympathetic withdrawal in addition to sympathetic enhancement (increased normalised low frequency component or LFnorm). In conclusion, this model is a highly sensitive and repeatable model to investigate HRV in anaesthetised cats that would be useful in the laboratory setting for short-term investigation of cardiovascular disease and subtle responses to pharmacological agents in this species.
    Matched MeSH terms: Electrocardiography/veterinary
  9. Piccini JP, Stromberg K, Jackson KP, Laager V, Duray GZ, El-Chami M, et al.
    Heart Rhythm, 2017 05;14(5):685-691.
    PMID: 28111349 DOI: 10.1016/j.hrthm.2017.01.026
    BACKGROUND: Device repositioning during Micra leadless pacemaker implantation may be required to achieve optimal pacing thresholds.

    OBJECTIVE: The purpose of this study was to describe the natural history of acute elevated Micra vs traditional transvenous lead thresholds.

    METHODS: Micra study VVI patients with threshold data (at 0.24 ms) at implant (n = 711) were compared with Capture study patients with de novo transvenous leads at 0.4 ms (n = 538). In both cohorts, high thresholds were defined as >1.0 V and very high as >1.5 V. Change in pacing threshold (0-6 months) with high (1.0 to ≤1.5 V) or very high (>1.5 V) thresholds were compared using the Wilcoxon signed-rank test.

    RESULTS: Of the 711 Micra patients, 83 (11.7%) had an implant threshold of >1.0 V at 0.24 ms. Of the 538 Capture patients, 50 (9.3%) had an implant threshold of >1.0 V at 0.40 ms. There were no significant differences in patient characteristics between those with and without an implant threshold of >1.0 V, with the exception of left ventricular ejection fraction in the Capture cohort (high vs low thresholds, 53% vs 58%; P = .011). Patients with an implant threshold of >1.0 V decreased significantly (P < .001) in both cohorts. Micra patients with high and very high thresholds decreased significantly (P < .01) by 1 month, with 87% and 85% having 6-month thresholds lower than the implant value. However, when the capture threshold at implant was >2 V, only 18.2% had a threshold of ≤1 V at 6 months and 45.5% had a capture threshold of >2 V.

    CONCLUSIONS: Pacing thresholds in most Micra patients with elevated thresholds decrease after implant. Micra device repositioning may not be necessary if the pacing threshold is ≤2 V.

    Matched MeSH terms: Electrocardiography*
  10. Malarvili MB, Mesbah M
    IEEE Trans Biomed Eng, 2009 Nov;56(11):2594-603.
    PMID: 19628449 DOI: 10.1109/TBME.2009.2026908
    In this paper, we investigate the use of heart rate variability (HRV) for automatic newborn seizure detection. The proposed method consists of a sequence of processing steps, namely, obtaining HRV from the ECG, extracting a discriminating HRV feature set, selecting an optimal subset from the full feature set, and, finally, classifying the HRV into seizure/nonseizure using a supervised statistical classifier. Due to the fact that HRV signals are nonstationary, a set of time-frequency features from the newborn HRV is proposed and extracted. In order to achieve efficient HRV-based automatic newborn seizure detection, a two-phase wrapper-based feature selection technique is used to select the feature subset with minimum redundancy and maximum class discriminability. Tested on ECG recordings obtained from eight newborns with identified EEG seizure, the proposed HRV-based neonatal seizure detection algorithm achieved 85.7% sensitivity and 84.6% specificity. These results suggest that the HRV is sensitive to changes in the cardioregulatory system induced by the seizure, and therefore, can be used as a basis for an automatic seizure detection.
    Matched MeSH terms: Electrocardiography/methods
  11. Birkhahn RH, Gaeta TJ, Melniker L
    J Emerg Med, 2000 Feb;18(2):199-202.
    PMID: 10699522
    A 27-year-old male of Malaysian descent presented to the Emergency Department (ED) with rapidly progressive flaccid paralysis that quickly compromised his respiratory effort. The patient was found to have a serum potassium of 1.9 meq/L, and was diagnosed as having an acute paralytic episode secondary to thyrotoxic periodic paralysis. The paralytic attack was aborted with a combination of potassium replacement and parenteral propranolol in large doses. We report the use of a rarely described, yet possibly more effective, therapy for an acute attack of thyrotoxic periodic paralysis.
    Matched MeSH terms: Electrocardiography
  12. McDOUGALL C
    Med J Malaya, 1955 Mar;9(3):195-204.
    PMID: 14393209
    Matched MeSH terms: Electrocardiography/instrumentation*
  13. Mahmod M, Mohd Darul ND, Mokhtar I, Md Nor N, Md Anshar F, Maskon O
    Int J Infect Dis, 2009 Sep;13(5):e316-8.
    PMID: 19541521 DOI: 10.1016/j.ijid.2009.01.017
    While electrocardiogram (ECG) changes are common during viral dengue infection, atrial fibrillation (AF) is a very rare manifestation. It has previously been highlighted that cardiac complications during dengue infection are invariably transient and will spontaneously resolve following recovery from the illness. We present the case of a young patient with IgM- and IgG-positive dengue hemorrhagic fever complicated by AF. ECG revealed a structurally normal heart. The patient remained in AF despite resolution of the illness. Reversion to normal sinus rhythm was achieved after loading of oral amiodarone.
    Matched MeSH terms: Electrocardiography
  14. Boon KH, Khalil-Hani M, Malarvili MB
    Comput Methods Programs Biomed, 2018 Jan;153:171-184.
    PMID: 29157449 DOI: 10.1016/j.cmpb.2017.10.012
    This paper presents a method that able to predict the paroxysmal atrial fibrillation (PAF). The method uses shorter heart rate variability (HRV) signals when compared to existing methods, and achieves good prediction accuracy. PAF is a common cardiac arrhythmia that increases the health risk of a patient, and the development of an accurate predictor of the onset of PAF is clinical important because it increases the possibility to electrically stabilize and prevent the onset of atrial arrhythmias with different pacing techniques. We propose a multi-objective optimization algorithm based on the non-dominated sorting genetic algorithm III for optimizing the baseline PAF prediction system, that consists of the stages of pre-processing, HRV feature extraction, and support vector machine (SVM) model. The pre-processing stage comprises of heart rate correction, interpolation, and signal detrending. After that, time-domain, frequency-domain, non-linear HRV features are extracted from the pre-processed data in feature extraction stage. Then, these features are used as input to the SVM for predicting the PAF event. The proposed optimization algorithm is used to optimize the parameters and settings of various HRV feature extraction algorithms, select the best feature subsets, and tune the SVM parameters simultaneously for maximum prediction performance. The proposed method achieves an accuracy rate of 87.7%, which significantly outperforms most of the previous works. This accuracy rate is achieved even with the HRV signal length being reduced from the typical 30 min to just 5 min (a reduction of 83%). Furthermore, another significant result is the sensitivity rate, which is considered more important that other performance metrics in this paper, can be improved with the trade-off of lower specificity.
    Matched MeSH terms: Electrocardiography
  15. Ang KP, Nordin RB, Lee SCY, Lee CY, Lu HT
    Med J Malaysia, 2019 02;74(1):51-56.
    PMID: 30846663
    INTRODUCTION: We aim to study the diagnostic value of electrocardiogram (ECG) in cardiac tamponade.

    METHODS: This study was a single centre, retrospective casecontrol study. We recruited 42 patients diagnosed with cardiac tamponade of various aetiologies confirmed by transthoracic echocardiography and 100 controls between January 2011 and December 2015. The ECG criteria of cardiac tamponade we adopted was as follows: 1) Low QRS voltage in a) the limb leads alone, b) in the precordial leads alone or, c) in all leads, 2) PR segment depression, 3) Electrical alternans, and 4) Sinus tachycardia.

    RESULTS: Malignancy was the most common causes of cardiac tamponade, the two groups were of similar proportion of gender and ethnicity. We calculated the sensitivity (SN), specificity (SP), positive predictive value (PPV), and negative predictive value (NPV) of each ECG criteria. Among the ECG abnormalities, we noted the SN of 'low voltage in all chest leads' (69%), 'low voltage in all limb leads' (67%) and 'sinus tachycardia' (69%) were higher as compared to 'PR depression' (12%) and 'electrical alternan' (5%). On the other hand, 'low voltage in all chest leads' (98%), 'low voltage in all leads' (99%), 'PR depression' (100%) and 'electrical alternans' (100%) has highest SP.

    CONCLUSION: Our study reaffirmed the findings of previous studies that electrocardiography cannot be used as a screening tool for diagnosing cardiac tamponade due to its low sensitivity. However, with clinical correlation, electrocardiography is a valuable adjuvant test to 'rule in' cardiac tamponade because of its high specificity.

    Matched MeSH terms: Electrocardiography*
  16. Ang KP, Quek ZQ, Lee CY, Lu HT
    Med J Malaysia, 2019 12;74(6):561-563.
    PMID: 31929492
    The clinical presentation of acute myocarditis is highly variable ranging from no symptoms to cardiogenic shock. Despite considerable progress, it remains a challenge for frontline physicians to discriminate between acute myocarditis and myocardial infarction, especially in the early phase. Our case serves as a reminder that acute presentation of myocarditis could resemble ST elevation myocardial infarction potentially misdirecting the therapeutic decision. The clinical presentation, electrocardiographic and laboratory findings of the patient are not specific enough to distinguish acute myocarditis from myocardial infarction. The gold standard tests such coronary angiography and cardiovascular magnetic resonance (CMR) can reliably differentiate the two entities.
    Matched MeSH terms: Electrocardiography
  17. Lim PK, Ng SC, Jassim WA, Redmond SJ, Zilany M, Avolio A, et al.
    Sensors (Basel), 2015 Jun 16;15(6):14142-61.
    PMID: 26087370 DOI: 10.3390/s150614142
    We present a novel approach to improve the estimation of systolic (SBP) and diastolic blood pressure (DBP) from oscillometric waveform data using variable characteristic ratios between SBP and DBP with mean arterial pressure (MAP). This was verified in 25 healthy subjects, aged 28 ± 5 years. The multiple linear regression (MLR) and support vector regression (SVR) models were used to examine the relationship between the SBP and the DBP ratio with ten features extracted from the oscillometric waveform envelope (OWE). An automatic algorithm based on relative changes in the cuff pressure and neighbouring oscillometric pulses was proposed to remove outlier points caused by movement artifacts. Substantial reduction in the mean and standard deviation of the blood pressure estimation errors were obtained upon artifact removal. Using the sequential forward floating selection (SFFS) approach, we were able to achieve a significant reduction in the mean and standard deviation of differences between the estimated SBP values and the reference scoring (MLR: mean ± SD = -0.3 ± 5.8 mmHg; SVR and -0.6 ± 5.4 mmHg) with only two features, i.e., Ratio2 and Area3, as compared to the conventional maximum amplitude algorithm (MAA) method (mean ± SD = -1.6 ± 8.6 mmHg). Comparing the performance of both MLR and SVR models, our results showed that the MLR model was able to achieve comparable performance to that of the SVR model despite its simplicity.
    Matched MeSH terms: Electrocardiography
  18. Loh TF
    Med J Malaya, 1970 Jun;24(4):257-60.
    PMID: 4248345
    Matched MeSH terms: Electrocardiography
  19. Freestone B, Rajaratnam R, Hussain N, Lip GY
    Int J Cardiol, 2003 Oct;91(2-3):233-8.
    PMID: 14559136
    BACKGROUND: There are established differences in cardiovascular disease in different racial groups. Worldwide, the literature regarding the clinical epidemiology of atrial fibrillation in non-white populations is scarce.

    OBJECTIVES: To document the prevalence of atrial fibrillation (AF) in the multiracial population of Malaysia, and to describe the clinical features and management of these patients.

    SETTING: Busy city centre general hospital in Kuala Lumpur, Malaysia, over a 1-month period.

    SUBJECTS: One-thousand four hundred and thirty-five acute medical admissions, of whom 40 patients (2.8%) had AF.

    RESULTS: Of 1435 acute medical admissions to Kuala Lumpur General Hospital over the 4-week study period, 40 had AF (21 male, 19 female; mean age 65 years). Of these, 18 were Malay, 16 Chinese and six Indian. Nineteen patients had previously known AF (seven with paroxysmal AF) and 21 were newly diagnosed cases. The principal associated medical conditions were ischaemic heart disease (42.5%), hypertension (40%) and heart failure (40%). Dyspnoea was the commonest presentation, whilst stroke was the cause of presentation in only two patients. Investigations were under-utilised, with chest X-ray and echocardiography in only 62.5% of patients and thyroid function checked in 15%. Only 16% of those with previously diagnosed AF were on warfarin, with a further three on aspirin. Anticoagulant therapy was started in 13.5% of patients previously not on warfarin, and aspirin in 8%. Records of contraindications to warfarin were unreliable, being identified in only 25%. For those with known AF, 58% were on digoxin. For new onset AF, digoxin was again the most common rate-limiting treatment, initiated in 38%, whilst five patients with new onset AF were commenced on amiodarone. DC cardioversion was not used in any of the patients with new onset AF.

    CONCLUSION: Amongst acute medical admissions to a single centre in Malaysia the prevalence of AF was 2.8%. Consistent with previous similar surveys in mainly western (caucasian) populations, standard investigations in this Malaysian cohort were also inadequate and there was underuse of anticoagulation, medication for ventricular rate control and cardioversion to sinus rhythm.

    Matched MeSH terms: Electrocardiography
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