| 1. |
- Sun, Y, et al.
(författare)
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Estimation of volume flow rate by surface integration of velocity vectors from color Doppler images.
- 1995
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Ingår i: Journal of the American Society of Echocardiography. - 0894-7317 .- 1097-6795 .- 0735-1097 .- 1558-3597. ; 8:6, s. 904-914
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Tidskriftsartikel (refereegranskat)abstract
- A new Doppler echocardiographically based method has been developed to quantify volume flow rate by surface integration of velocity vectors (SIVV). Electrocardiographic-gated color Doppler images acquired in two orthogonal planes were used to estimate volume flow rate through a bowl-shaped surface at a given time and distance from the probe. To provide in vitro validation, the method was tested in a hydraulic model representing a pulsatile flow system with a restrictive orifice. Accurate estimates of stroke volume (+/- 10%) were obtained in a window between 1.2 and 1.6 cm proximal to the orifice, just before the region of prestenotic acceleration. By use of the Bernoulli's equation, the estimated flows were used to generate pressure gradient waveforms across the orifice, which agreed well with the measured flows. To demonstrate in vivo applicability, the SIVV method was applied retrospectively to the determination of stroke volume and subaortic flow from the apical three-chamber and five-chamber views in two patients. Stroke volume estimates along the left ventricular outflow tract showed a characteristic similar to that in the in vitro study and agreed well with those obtained by the Fick oxygen method. The region where accurate measurements can be obtained is affected by instrumental factors including Nyquist velocity limit, wall motion filter cutoff, and color flow sector angle. The SIVV principle should be useful for quantitative assessment of the severity of valvular abnormalities and noninvasive measurement of pulsatile volume flows in general.
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| 3. |
- Hedén, Bo, et al.
(författare)
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Agreement between artificial neural networks and experienced electrocardiographer on electrocardiographic diagnosis of healed myocardial infarction
- 1996
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Ingår i: Journal of the American College of Cardiology. - 0735-1097. ; 28:4, s. 1012-1016
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Tidskriftsartikel (refereegranskat)abstract
- Objectives. The purpose of this study was to compare the diagnoses of healed myocardial infarction made from the 12-lead electrocardiogram (ECG) by artificial neural networks and an experienced electrocardiographer. Background. Artificial neural networks have proved of value in pattern recognition tasks. Studies of their utility in ECG interpretation have shown performance exceeding that of conventional ECG interpretation programs. The latter present verbal statements, often with an indication of the likelihood for a certain diagnosis, such as 'possible left ventricular hypertrophy'. A neural network presents its output as a numeric value between 0 and 1; however, these values can be interpreted as Bayesian probabilities. Methods. The study was based on 351 healthy volunteers and 1,313 patients with a history of chest pain who had undergone diagnostic cardiac catheterization. A 12-lead ECG was recorded in each subject. An expert electrocardiographer classified the ECGs in five different groups by estimating the probability of anterior myocardial infarction. Artificial neural networks were trained and tested to diagnose anterior myocardial infarction. The network outputs were divided into five groups by using the output values and four thresholds between 0 and 1. Results. The neural networks diagnosed healed anterior myocardial infarctions at high levels of sensitivity and specificity. The network outputs were transformed to verbal statements, and the agreement between these probability estimates and those of an expert electrocardiographer was high. Conclusions. Artificial neural networks can be of value in automated interpretation of ECGs in the near future.
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| 4. |
- Liuba, Petru, et al.
(författare)
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Predictors of early postoperative complications after arterial switch operation of newborns with transposition of the great arteries
- 2014
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Ingår i: Journal of the American College of Cardiology. - 0735-1097. ; 63:12, Suppl 1, s. 584-584
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Konferensbidrag (refereegranskat)abstract
- Background: Lund is one of the two tertiary referral centers for pediatric cardiac surgery in Sweden, with nearly 350 surgical procedures every year. We performed a retrospective analysis of newborns and infants with transposition of the great arteries (TGA) operated with arterial switch (ASO) during the past 10 years. Methods: a single-institution retrospective analysis of nearly 100 newborns and infants with transposition of the great arteries (TGA) operated with arterial switch during the past 10 years. Postoperative morbidity and mortality during the the first month was recorded.Patients with TGA/double outlet right ventricle were excluded from the analysis. Results: 103 patients with TGA (median for birth weight, gestational week, and age at surgery: 3.5 kg, 39 weeks, and 4 days) were included. There was only 1 death. Surgery beyond 5 days of age (n=46) was associated with prolonged mechanical ventilation (p
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| 5. |
- Pettersson, Jonas, et al.
(författare)
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Changes in high-frequency QRS components are more sensitive than ST segment deviation for detecting acute coronary artery occlusion
- 2000
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Ingår i: Journal of the American College of Cardiology. - 0735-1097. ; 36:6, s. 1827-1834
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES This study describes changes in high-frequency QRS components (HF-QRS) during percutaneous transluminal coronary angioplasty (PTCA) and compares the ability of these changes in HF-QRS and ST-segment deviation in the standard 12-lead electrocardiogram (ECG) to detect acute coronary artery occlusion. BACKGROUND Previous studies have shown decreased HF-QRS in the frequency range of 150–250 Hz during acute myocardial ischemia. It would be important to know whether the high-frequency analysis could add information to that available from the ST segments in the standard ECG. METHODS The study population consisted of 52 patients undergoing prolonged balloon occlusion during PTCA. Signal-averaged electrocardiograms (SAECG) were recorded prior to and during the balloon inflation. The HF-QRS were determined within a bandwidth of 150–250 Hz in the preinflation and inflation SAECGs. The ST-segment deviation during inflation was determined in the standard frequency range. RESULTS The sensitivity for detecting acute coronary artery occlusion was 88% using the high-frequency method. In 71% of the patients there was ST elevation during inflation. If both ST elevation and depression were considered, the sensitivity was 79%. The sensitivity was significantly higher using the high-frequency method, p < 0.002, compared with the assessment of ST elevation. CONCLUSIONS Acute coronary artery occlusion is detected with higher sensitivity using high-frequency QRS analysis compared with conventional assessment of ST segments. This result suggests that analysis of HF-QRS could provide an adjunctive tool with high sensitivity for detecting acute myocardial ischemia.
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| 7. |
- Andersson, Bert, 1952, et al.
(författare)
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The DD genotype of the angiotensin-converting enzyme gene is associated with increased mortality in idiopathic heart failure.
- 1996
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Ingår i: Journal of the American College of Cardiology. - : Elsevier BV. - 0735-1097. ; 28:1, s. 162-7
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the present study was to investigate the association between the homozygous DD (deletion) genotype of the angiotensin-converting enzyme gene and survival and cardiac function in patients with idiopathic congestive heart failure.The DD genotype gene is a linkage marker for an etiologic mutation at or near the angiotensin-converting enzyme gene and has been associated with increased risk for the development of coronary artery disease, left ventricular hypertrophy and left ventricular dilation after myocardial infarction. We investigated the association between this angiotensin-converting enzyme genotype and mortality in a population-based cohort of patients with idiopathic congestive heart failure.The genotype was determined in 193 patients recruited from a large unselected population of patients with congestive heart failure (n = 2,711). The patients were studied with echocardiography, and survival data were obtained after 5 years of follow-up. A control group from the general population (n = 77) was studied by a similar procedure.The frequency of the D allele was not significantly different in the study and control groups (0.57 vs 0.56, p = NS). Long-term survival was significantly worse in the patients with the DD genotype than in the remaining patients (5-year survival rate 49% vs. 72%, p = 0.0011 as assessed by log rank test). The independent importance of the DD genotype for prognosis was verified by a multivariate Cox proportional hazards analysis, by which the odds ratio for mortality and the DD genotype was 1.69 (95% confidence interval 1.01 to 2.82). The only significant difference in cardiac function data between the two groups was an increase in left ventricular mass index in the DD group (153 +/- 57 vs 134 +/- 44 g/m2, p = 0.019).Angiotensin-converting enzyme gene DD polymorphism was associated with poorer survival and an increase in left ventricular mass in patients with idiopathic heart failure. The results suggest a possible pathophysiologic pathway between angiotensin-converting enzyme gene polymorphism, angiotensin-converting enzyme activity, myocardial hypertrophy and survival. Therefore, the DD genotype may be a marker of poor prognosis in patients with congestive heart failure.
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