ABSTRACT
The amplifier is easy to saturation because of polarization voltage in ambulatory ECG acquisition. The traditional way is using analog high-pass filter to eliminate, but the output tends to have a residue. If upgrading high-pass filter cutoff frequency, it will lead to low frequency distortion of ECG signals. In this paper, a Savitzky-Golay (SG) smoothing filter has been designed by combining the single edge point and the polynomial order , which can fit the polarization voltage components of ECG signals, filter useful components and get drift-free ECG signals by using the subtraction algorithm. The results of ECG filtering experiment verify the feasibility of the SG smoothing filter, and show the filtered ECG signal without any losses of useful components.
Subject(s)
Humans , Algorithms , Amplifiers, Electronic , Electrocardiography, Ambulatory , Methods , Signal Processing, Computer-AssistedABSTRACT
ABSTRACT: The aim of the present study was to assess heart rate variability (HRV) in Boxer dogs affected by arrhythmogenic right ventricular cardiomyopathy (ARVC). Fourteen Boxer dogs classified as affected and 28 classified as unaffected were included in a prospective case-control study. Dogs underwent 24-hour ambulatory ECG and were classified as affected (>1,000 VPCs/24 hours) or unaffected (<20 VPCs/24 hours) by ARVC based on the number of ventricular arrhythmias. HRV was assessed using 24-h Holter ECG monitoring; the studied parameters were SDNN, SDANN, SDNNIDX, rMSSD and pNN50. Data were submitted to logarithmic transformation and HRV parameters were compared between groups and correlated according to the disease status, number and severity of ventricular arrhythmias using Student’s t test, linear regression and Spearman’s test. There was no interaction between the HRV parameters and the number and severity of ventricular arrhythmias. SDNNlog (2.35±0.14 vs. 2.46±0.12, P=0.01), SDNNIDXlog (2.18±0.14 vs. 2.24±0.10, P=0.002) and pNN50log (1.47±0.19 vs. 1.64±0.13, P=0.002) were significantly lower in the affected group compared with the unaffected. According to this study, HRV are different in a population of Boxers dogs affected by ARVC compared to a population of unaffected dogs, and these differences are not consequences of low cardiac output caused by ventricular arrhythmias since animals that had higher number and complexity of arrhythmias were not those who had lower values of HRV.
RESUMO: O objetivo do presente estudo foi avaliar a variabilidade da frequência cardíaca (VFC) em cães da raça Boxer acometidos pela cardiomiopatia arritmogênica do ventrículo direito (CAVD). Para isso, foram incluídos, em estudo prospectivo caso-controle, 14 cães classificados como acometidos pela CAVD e 28 classificados como não acometidos. Os cães foram submetidos à eletrocardiografia ambulatorial de 24 horas e então classificados como acometidos (quando apresentaram mais de 1.000 complexos ventriculares prematuros em 24 horas) ou não acometidos (quando apresentaram menos de 20 complexos ventriculares prematuros em 24 horas) pela CAVD, com base no número de arritmias ventriculares. A VFC foi avaliada mediante monitoramento Holter de 24 horas. Os parâmetros estudados foram SDNN, SDANN, SDNNIDX, rMSSD e pNN50. Os dados foram submetidos à transformação logarítmica e os parâmetros da VFC foram comparados e correlacionados de acordo com a presença ou não da doença, número e severidade das arritmias pelo teste t de Student, regressão linear e teste de Spearman. Não houve interação entre as variáveis da VFC e o número e a severidade das arritmias ventriculares. Porém, as variáveis SDNNlog (2,35±0,14 vs. 2,46±0,12, P=0,01), SDNNIDXlog (2,18±0,14 vs. 2,24±0,10, P=0.002) e pNN50log (1,47±0,19 vs. 1,64±0,13, P=0,002) foram significativamente menores no grupo de animais acometidos pela doença. De acordo com os resultados do presente estudo, a VFC é menor nos Boxers acometidos pela CAVD em relação aos cães não acometidos, e essa diferença não pode ser atribuída ao baixo débito cardíaco, supostamente causado pelas arritmias ventriculares, uma vez que os animais que apresentaram maior número e complexidade das arritmias não foram os que apresentaram os menores valores da VFC.
ABSTRACT
The ambulatory electrocardiographic examinations were performed in 31 patients (mean age of 59.4+/-9.3 yrs : male 16 cases, female 15 cases) with ischemic heart disease to evaluate the clinical features of ST segment more than 1 mm persisting for 45 seconds or longer. The incidence of associated disease are angina pectoris 14 cases, acute myocardial infarction 3 cases, old myocardial infarction 7 cases, hypertension 19 cases, diabetes mellitus 5 cases, cerebrovascular disease 4 cases, aortic regurgitation 2 cases, ventricular arrhythmia 1 case and chronic renal faliure 1 case. 93.7% of 252 monitored episodes of transient myocardial ischemia were silent. The incidence and duration of transient myocardial ischemia were 8.1+/-6.7 episodes/day (7.6+/-6.5episodes/day for silent myocardial ischemia, 0.5+/-0.9 episodes/day for silent ischemia, 7.6+/-14.1mins/day for symptomatic ischemia). The heart rate at the onset of ST segment depression is higher in symptomatic episode than silent episode (94.6+/-19.7 vs 82.1+/-17.4/min,. p<0.05). But duration of ST segment depression is longer in silent episode than symptomatic episode(32.4+/-97.7 vs 14.8+/-10.2/min,. p<0.01). Maximal ST segment depression was similar between silent and symptomatic episode (1.61+/-0.65 mm, 1.97+/-0.84 mm, repectively). 55.5% of silent episodes occurred during sleep or resting state and 60% of symptomatic episodes occurred during strenuous effort, exercise or eating (p<0.01). Transient myocardial ischemia developed not more frequently in the morning probably because the 24 hour Holter electrocadiographic examination was performed during hospitalization in the majority of cases.