A study on the effect of contact pressure during physical activity on photoplethysmographic heart rate measurements

Heart rate (HR) as an important physiological indicator could properly describe global subject’s physical status. Photoplethysmographic (PPG) sensors are catching on in field of wearable sensors, combining the advantages in costs, weight and size. Nevertheless, accuracy in HR readings is unreliable specifically during physical activity. Among several identified sources that affect PPG recording, contact pressure (CP) between the PPG sensor and skin greatly influences the signals. Methods: In this study, the accuracy of HR measurements of a PPG sensor at different CP was investigated when compared with a commercial ECG-based chest strap used as a test control, with the aim of determining the optimal CP to produce a reliable signal during physical activity. Seventeen subjects were enrolled for the study to perform a physical activity at three different rates repeated at three different contact pressures of the PPG-based wristband. Results: The results show that the CP of 54 mmHg provides the most accurate outcome with a Pearson correlation coefficient ranging from 0.81 to 0.95 and a mean average percentage error ranging from 3.8% to 2.4%, based on the physical activity rate. Conclusion: Authors found that changes in the CP have greater effects on PPG-HR signal quality than those deriving from the intensity of the physical activity and specifically, the individual best CP for each subject provided reliable HR measurements even for a high intensity of physical exercise with a Bland–Altman plot within ±11 bpm. Although future studies on a larger cohort of subjects are still needed, this study could contribute a profitable indication to enhance accuracy of PPG-based wearable devices

Echocardiography to estimate high filling pressure in patients with heart failure and reduced ejection fraction

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Comparison of right ventricular longitudinal strain imaging, tricuspid annular plane systolic excursion, and cardiac biomarkers for early diagnosis of cardiac involvement and risk stratification in primary systematic (AL) amyloidosis: a 5-year cohort study: reply.

http://www.ncbi.nlm.nih.gov/pubmed/2336252

Update on tricuspid regurgitation

Although commonly detected by transthoracic echocardiography, tricuspid regurgitation (TR) has been somehow neglected, and recent data have emerged on the need for careful examination of the tricuspid valve. Functional or secondary TR is the most frequent etiology of tricuspid valve pathology in western countries and is related to tricuspid annular dilation and leaflet tethering. The prognostic role of TR associated with organic left-sided valvular heart disease is well known. However, the value of functional TR in outcome stratification of patients with advanced left ventricular dysfunction is less clear. Surgical tricuspid repair has been avoided for years, because of the misconception that TR should disappear once the primary left-sided problem is treated; this results in a large number of untreated patients with functional TR. Over the past few years, many investigators have reported evidence in favor of a more aggressive surgical approach to functional TR. Consequently, interest has been growing in the pathophysiology and treatment of functional TR. The purpose of this article is to provide a comprehensive review of TR incorporating a description of valve anatomy, etiological factors, pathophysiology, epidemiological data, natural history, clinical evaluation, along with a discussion of the important role in prognostic stratification and a summary of management guideline

Systolic characteristics and dynamic changes of the mitral valve in different grades of ischemic mitral regurgitation - insights from 3D transesophageal echocardiography

Background: Mitral regurgitation in ischemic heart disease (IMR) is a strong predictor of outcome but until now, pathophysiology is not sufficiently understood and treatment is not satisfying. We aimed to systematically evaluate structural and functional mitral valve leaflet and annular characteristics in patients with IMR to determine the differences in geometric and dynamic changes of the MV between significant and mild IMR. Methods: Thirty-seven patients with IMR (18 mild (m)MR, 19 significant (moderate+severe) (s)MR) and 33 controls underwent TEE. 3D volumes were analyzed using 3D feature-tracking software. Results: All IMR patients showed a loss of mitral annular motility and non-planarity, whereas mitral annulus dilation and leaflet enlargement occurred in sMR only. Active-posterior-leaflet-area decreased in early systole in all three groups accompanied by an increase in active-anterior-leaflet-area in early systole in controls and mMR but only in late systole in sMR. Conclusions: In addition to a significant enlargement and loss in motility of the MV annulus, patients with significant IMR showed a spatio-temporal alteration of the mitral valve coaptation line due to a delayed increase in active-anterior-leaflet-area. This abnormality is likely to contribute to IMR severity and is worth the evaluation of becoming a parameter for clinical decision-making. Further, addressing the leaflets aiming to increase the active leaflet-area is a promising therapeutic approach for significant IMR. Additional studies with a larger sample size and post-operative assessment are warranted to further validate our findings and help understand the dynamics of the mitral valve

Association of cardio-pulmonary stress test parameters and heart rate recovery in obese subjects with or without type II diabetes

Background and Objectives: Heart rate recovery at first (HRR-I) and second (HRR-II) minute after exercise is accurate in estimating autonomic nervous system balance, and has been related to risk of cardiovascular events. Our aim was to determine independent predictors of HRR collected during standard cardio-pulmonary stress test (CPT) in a group of overweight/obese subjects without (N=14) and with type 2 diabetes (N=19), as compared to a sample (N=15) of healthy sedentary subjects. Methods: A graded exercise test on treadmill was performed. Oxygen uptake at rest and at peak exercise (VO2max), as well as respiratory exchange ratio at peak exercise was collected. Linear and logistic regression was used to assess association between variables collected at CPT and HRR-I and HRR-II. Results: Age, gender, as well as VO2 and HR at rest were all comparable among groups. VO2max and HRmax were both lower in diabetic patients as compared to healthy and overweight/obese groups (20 ± 4.3 vs. 28 ± 7 vs. 25.1 ± 5 ml/Kg/min respectively, p < 0.01). VO2max had the highest association to HRR-I (R2=0.47) and HRR-II (R2=0.44); VO2max < 28 and VO2max < 29 were the most accurate cut-off values to identify subjects with abnormally low HRR-I and HRR-II. Conclusions: VO2max is an independent predictor of HRR-I or HRR-II, and it is able to discriminate between patients with normal or abnormally low HRR values. Further studies are warranted to test usefulness of a customized exercise program to ameliorate autonomic nervous system balance, therefore reducing global cardiovascular risk