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| 2. |
- Hnatkova, K, et al.
(författare)
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Computer package generating non-invasive atrial electrograms: Detection and subtraction of QRS and T waves
- 1998
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Ingår i: Computers in Cardiology. - 0780352009 ; 25, s. 533-536
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Konferensbidrag (refereegranskat)abstract
- Computerized systems to localize specific patterns appearing in ECG signal, such as the QRS complex and T wave usually utilize predefined templates. Where the signal is not clean, such as during atrial fibrillation (AF), analysis based on self-similarities of the ECG signal appears to be more stable. The authors describe a software package which uses self-similarity techniques to allow the subtraction of ventricular signals during AF. The dataset used in this study was Holter ECG recorded in 23 patients (11 male, age 61.1±8.7 years) with chronic AF using an Altair 6500 digital Holter (Burdick Inc., 3 channels, 1 kHz sampling). Self-similarities between corresponding QRS and corresponding T windows were assessed using Spearman correlation coefficients, utilising the commercial software derived fiducial point but with shifted windows to overcome possible minor imprecision thereof. A linear order algorithm successfully subtracted 87% of QRS's and 67% of T waves.
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| 3. |
- Ingvarsson, Annika, et al.
(författare)
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Normal Reference Ranges for Transthoracic Echocardiography Following Heart Transplantation
- 2018
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Ingår i: Journal of the American Society of Echocardiography. - : Elsevier BV. - 0894-7317. ; 31:3, s. 349-360
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Tidskriftsartikel (refereegranskat)abstract
- Background: Heart function following heart transplantation (HTx) is influenced by numerous factors. It is typically evaluated using transthoracic echocardiography, but reference values are currently unavailable for this context. The primary aim of the present study was to derive echocardiographic reference values for chamber size and function, including cardiac mechanics, in clinically stable HTx patients. Methods: The study enrolled 124 healthy HTx patients examined prospectively. Patients underwent comprehensive two-dimensional echocardiographic examinations according to contemporary guidelines. Results were compared with recognized reference values for healthy subjects. Results: Compared with guidelines, larger atrial dimensions were seen in HTx patients. Left ventricular (LV) diastolic volume was smaller, and LV wall thickness was increased. With respect to LV function, both ejection fraction (62 ± 7%, P < .01) and global longitudinal strain (-16.5 ± 3.3%, P < .0001) were lower. All measures of right ventricular (RV) size were greater than reference values (P < .0001), and all measures of RV function were reduced (tricuspid annular plane systolic excursion 15 ± 4 mm [. P < .0001], RV systolic tissue Doppler velocity 10 ± 6 cm/sec [. P < .0001], fractional area change 40 ± 8% [. P < .0001], and RV free wall strain -16.9 ± 4.2% [. P < .0001]). Ejection fraction and LV global longitudinal strain were significantly lower in patients with previous rejection. Conclusion: The findings of this study indicate that the distribution of routinely used echocardiographic measures differs between stable HTx patients and healthy subjects. In particular, markedly larger RV and atrial volumes and mild reductions in both LV and RV longitudinal strain were evident. The observed differences could be clinically relevant in the assessment of HTx patients, and specific reference values should be applied in this context.
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| 4. |
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| 5. |
- Meurling, Carl, et al.
(författare)
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Diurnal variations of the dominant cycle length of chronic atrial fibrillation
- 2001
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Ingår i: American Journal of Physiology: Heart and Circulatory Physiology. - 1522-1539. ; 280:1, s. 401-406
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Tidskriftsartikel (refereegranskat)abstract
- High-resolution digital Holter recording was carried out in 21 patients (15 men, 64 +/- 12 yr) with chronic atrial fibrillation. Dominating atrial cycle length (DACL) was derived by frequency domain analysis of QRST-reduced electrocardiograms. Daytime mean DACL was 150 +/- 17 ms, and nighttime mean was 157 +/- 22 ms (P = 0. 0002). Diurnal fluctuation in DACL differed among patients: it tended to be virtually absent in those with a short mean DACL, but in those with longer DACL the night-day difference was as much as 23 ms (R = 0.72, P < 0.001, correlation of mean DACL to night-day difference). Mean DACL also correlated with ventricular cycle length (R = 0.40, P < 0.001), particularly at night (r = 0.49). The shorter cycle lengths found in this study during the day are consistent with sympathetic and/or other physiological modulation, but since increased vagal tone shortens atrial refractoriness in most models, parasympathetic influences are not likely to play a major role. Alternatively, atrial effective refractory period may not be the sole determinant of atrial cycle length during atrial fibrillation.
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| 6. |
- Werther Evaldsson, A., et al.
(författare)
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Echocardiographic right ventricular strain from multiple apical views is superior for assessment of right ventricular systolic function
- 2019
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Ingår i: Clinical Physiology and Functional Imaging. - : Wiley. - 1475-0961. ; 39:2, s. 168-176
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Tidskriftsartikel (refereegranskat)abstract
- Background: Right ventricular (RV) systolic function is an important determinant of outcome in patients with pulmonary hypertension (PH). Conventional echocardiographic measures of RV are mainly based on longitudinal contractility. Recently, measurement of RV global longitudinal strain derived from multiple windows (RVGLS) has emerged as an option but has not been well evaluated. The aim of the present study was to evaluate which echocardiographic RV function parameter correlates best with RV ejection fraction derived from cardiac magnetic resonance imaging (RVEFCMR). Methods and results: Fifty-five patients evaluated for PH underwent RV assessment with echocardiography and CMR. Conventional echocardiographic parameters of RV function including tricuspid annular plane systolic excursion (TAPSE), tricuspid annular systolic velocity (S′), RV fractional area change (RVFAC) and RV index of myocardial performance (RIMP). RVGLS was measured from three separate apical views using a 17-segment model and strain from the lateral free wall was calculated separately (RVfree). The study included 55 patients, whereas assessment of RVGLS could be obtained in 29 patients. The Pearson correlation coefficient with RVEFCMR was strong for RVGLS (r = 0·814, P<0·001) and RVfree (r = 0·778, P<0·001), modest for RVFAC (r = 0·681, P<0·001), TAPSE (r = 0·592, P<0·001) and RIMP (r=−0·521, P<0·01), and weak for S′ (r = 0·385, P<0·01). Conclusion: The echocardiographic RV measures, RVGLS and RVfree correlated well with RVEFCMR, whereas correlation with TAPSE, RIMP and S′ was unsatisfactory. Our findings suggest that RVGLS and RVfree are the preferred echocardiographic methods for clinical practice. RVfree is easiest to perform but RVGLS could provide incremental value in selected patients.
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| 7. |
- Holmqvist, Fredrik, et al.
(författare)
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Variable interatrial conduction illustrated in a hypertrophic cardiomyopathy population
- 2007
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Ingår i: Annals of Noninvasive Electrocardiology. - 1082-720X. ; 12:3, s. 227-236
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Tidskriftsartikel (refereegranskat)abstract
- Background: Patients with hypertrophic cardiomyopathy (HCM) have a high incidence of atrial fibrillation. They also have a longer P-wave duration than healthy controls, indicating conduction alterations. Previous studies have demonstrated orthogonal P-wave morphology alterations in patients with paroxysmal atrial fibrillation. In the present study, the P-wave morphology of patients with HCM was compared with that of matched controls in order to explore the nature of the atrial conduction alterations. Methods and Results: A total of 65 patients (45 men, mean age 49 +/- 15) with HCM were included. The control population (n = 65) was age and gender matched (45 men, mean age 49 +/- 15). Five minutes of 12-lead ECG was recorded. The data were subsequently transformed to orthogonal lead data, and unfiltered signal-averaged P-wave analysis was performed. The P-wave duration was longer in the HCM patients compared to the controls (149 +/- 22 vs 130 +/- 16 ms, P < 0.0001). Examination of the P-wave morphology demonstrated changes in conduction patterns compatible with interatrial conduction block of varying severity in both groups, but a higher degree of interatrial block seen in the HCM population. These changes were most prominent in the Leads Y and Z. Conclusion: The present study suggests that the longer P-wave duration observed in HCM patients may be explained by a higher prevalence of block in one or more of the interatrial conduction routes.
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| 8. |
- Ingvarsson, Annika, et al.
(författare)
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Impact of bridging with left ventricular assist device on right ventricular function following heart transplantation.
- 2022
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Ingår i: ESC heart failure. - : Wiley. - 2055-5822. ; 9:3, s. 1864-1874
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Tidskriftsartikel (refereegranskat)abstract
- Patients awaiting orthotopic heart transplantation (OHT) can be bridged utilizing a left ventricular assist device (LVAD) that reduces left ventricular filling pressures, decreases pulmonary artery wedge pressure, and maintains adequate cardiac output. This study set out to examine the poorly investigated area of if and how pre-treatment with LVAD impacts right ventricular (RV) function following OHT.We prospectively evaluated 59 (LVAD n=20) consecutive OHT patients. Transthoracic echocardiography (TTE) was performed in conjunction with right heart catheterization (RHC) at 1, 6, and 12months after OHT. RV function TTE-parameters included tricuspid annular plane systolic excursion (TAPSE), systolic tissue velocity (S'), fractional area change, two-dimensional RV global longitudinal strain and longitudinal strain from the RV lateral wall (RVfree). At 1month after OHT, the LVAD group had significantly better longitudinal RV function than the non-LVAD group: TAPSE (15±3mm vs. 12±2mm, P<0.001), RV global longitudinal strain (-19.8±2.1% vs. -14.3±2.8%, P<0.001), and RVfree (-19.8±2.3% vs. -14.1±2.9%, P<0.001). At this time point, pulmonary vascular resistance (PVR) was also lower [1.2±0.4 Wood Units (WU) vs. 1.6±0.6 WU, P<0.05] in the LVAD group compared with the non-LVAD group. At 6 and 12months, no difference was detected in any of the TTE and RHC measured parameters between the two groups. Between 1 and 12months, all parameters of RV function improved significantly in the non-LVAD group but remained unaltered in the LVAD group.Our results indicate that pre-treatment with LVAD decreases PVR and is associated with significantly better RV function early following OHT. During the first year following transplantation, RV function progressively improved in the non-LVAD group such that at 6 and 12months, no difference in RV function was detected between the groups.
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| 9. |
- Ingvarsson, Annika, et al.
(författare)
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Impact of gender on echocardiographic characteristics in heart transplant recipients
- 2019
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Ingår i: Clinical Physiology and Functional Imaging. - : Wiley. - 1475-0961 .- 1475-097X. ; 39:4, s. 246-254
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Tidskriftsartikel (refereegranskat)abstract
- Aims: Assessment following heart transplantation (HTx) is routinely performed using transthoracic echocardiography. Differences in long-term mortality following HTx related to donor-recipient matching have been reported, but effects of gender on cardiac size and function are not well studied. The aims of this study were to evaluate differences in echocardiographic characteristics of HTx recipients defined by gender. Methods and results: The study prospectively enrolled 123 (n = 34 female) HTx recipients of which 23 recipients was donor-recipient gender mismatched. Patients were examined with 2-dimensional echocardiography using Philips iE33 ultrasound system. Data were analysed across strata based on recipient gender and gender mismatch. Male recipients had larger left ventricular (LV) mass, thicker septal wall (P<0·001) and larger absolute LV volumes (P<0·001). Mean LV ejection fraction (EF) was higher in females (P<0·05), but no differences in conventional parameters of right ventricular (RV) function were found. Ventricular strain was higher in females than in males: LV global longitudinal strain (P<0·01), RV global longitudinal strain (P<0·05) and RV lateral free wall (P<0·05). The male group receiving a female donor heart had comparable EF and strain parameters to the female group receiving a gender-matched heart. Conclusion: We found that female recipient gender was associated with smaller chamber size, higher LV EF and better LV and RV longitudinal strain. Gender-mismatched male recipients appeared to exhibit function parameters similar to gender-matched female recipients. Our results indicate that the gender aspect, analogous to current reference guidelines in general population, should be taken into consideration when examining patients post-HTx.
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| 10. |
- Werther Evaldsson, Anna, et al.
(författare)
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Right ventricular speckle tracking assessment for differentiation of pressure- versus volume-overloaded right ventricle
- 2018
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Ingår i: Clinical Physiology and Functional Imaging. - : Wiley. - 1475-0961. ; 38:5, s. 763-771
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Right ventricular (RV) dysfunction may be caused by either pressure or volume overload. RV function is conventionally assessed with echocardiography using tricuspid annular plane systolic excursion (TAPSE), RV fractional area change (RVFAC), tricuspid lateral annular systolic velocity (S') and RV index of myocardial performance (RIMP). The purpose of this study was to evaluate whether RV global longitudinal strain (RVGLS) and RV-free wall strain (RV-free) could add additional information to differentiate these two causes of RV overload.METHODS AND RESULTS: The study enrolled 89 patients with an echocardiographic trans-tricuspid gradient >30 mmHg. Forty-five patients with pulmonary arterial hypertension or chronic thromboembolic pulmonary hypertension (pressure overload) were compared with 44 patients with an atrial septum defect (volume overload). RV size was larger in the volume group (P<0·05). TAPSE and S' were lower in the pressure group (P<0·05, P<0·01). RVFAC was lower in the pressure group (P<0·001) as well as RVGLS (-12·1 ± 3·3% versus -20·2 ± 3·4%, P<0·001) and RV-free (-12·9 ± 3·3% versus -19·4 ± 3·4%, P<0·001).CONCLUSION: In this study, RVGLS and RV-free could more accurately discriminate RV pressure from volume overload than conventional measures. The reason could be that TAPSE and S' are unable to differentiate active deformation from passive entrainment caused by the left ventricle. The pressure group had evidence of marked RV hypertrophy despite standard functional parameters (TAPSE and S) within normal range. This would enhance the value of strain to more sensitively detect abnormal function. A cut-off value of below -16% for RVGLS and RV-free predicts RV pressure overload with high accuracy.
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