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Porta A.,University of Milan | Porta A.,IRCCS Galeazzi Orthopedic Institute | Bari V.,Vascular Anesthesia and Intensive Care | Marchi A.,Humanitas Clinical and Research Center | And 6 more authors.
Frontiers in Physiology | Year: 2015

Two diverse complexity metrics quantifying time irreversibility and local prediction, in connection with a surrogate data approach, were utilized to detect nonlinear dynamics in short heart period (HP) variability series recorded in fetuses, as a function of the gestational period, and in healthy humans, as a function of the magnitude of the orthostatic challenge. The metrics indicated the presence of two distinct types of nonlinear HP dynamics characterized by diverse ranges of time scales. These findings stress the need to render more specific the analysis of nonlinear components of HP dynamics by accounting for different temporal scales. © 2015 Porta, Bari, Marchi, De Maria, Cysarz, Van Leeuwen, Takahashi, Catai and Gnecchi-Ruscone.


Porta A.,University of Milan | Porta A.,IRCCS Galeazzi Orthopedic Institute | Girardengo G.,IRCCS Instituto Auxologico Italiano | Bari V.,Vascular Anesthesia and Intensive Care | And 7 more authors.
Journal of the American College of Cardiology | Year: 2015

Background A puzzling feature of the long QT syndrome (LQTS) is that family members carrying the same mutation often have divergent symptoms and clinical outcomes. Objectives This study tested the hypothesis that vagal and sympathetic control, as assessed by spectral analysis of spontaneous beat-to-beat variability of RR and QT intervals from standard 24-h electrocardiogram Holter recordings, could modulate the severity of LQTS type 1 (LQT1) in 46 members of a South-African LQT1 founder population carrying the clinically severe KCNQ1 A341V mutation. Methods Nonmutation carriers (NMCs) (n = 14) were compared with mutation carriers (MCs) (n = 32), 22 with and 10 without major symptoms. We assessed the effect of circadian rhythm and beta-blocker therapy over traditional time and frequency domain RR and QT variability indexes. Results The asymptomatic MCs differed significantly from the symptomatic MCs and from NMCs in less vagal control of heart rate and more reactive sympathetic modulation of the QT interval, particularly during daytime when arrhythmia risk for patients with LQT1 is greatest. Conclusions The present data identified an additional factor contributing to the differential arrhythmic risk among patients with LQT1 carrying the same mutation. A healthy autonomic control confers a high risk, whereas patients with higher sympathetic control of the QT interval and reduced vagal control of heart rate are at lower risk. This differential "autonomic make-up," likely under genetic control, will allow refinement of risk stratification within families with LQTS, leading to more targeted management. © 2015 American College of Cardiology Foundation.


PubMed | Vascular Anesthesia and Intensive Care, Humanitas Clinical and Research Center Rozzano, Federal University of São Carlos, University of Milan and 3 more.
Type: | Journal: Frontiers in physiology | Year: 2015

Two diverse complexity metrics quantifying time irreversibility and local prediction, in connection with a surrogate data approach, were utilized to detect nonlinear dynamics in short heart period (HP) variability series recorded in fetuses, as a function of the gestational period, and in healthy humans, as a function of the magnitude of the orthostatic challenge. The metrics indicated the presence of two distinct types of nonlinear HP dynamics characterized by diverse ranges of time scales. These findings stress the need to render more specific the analysis of nonlinear components of HP dynamics by accounting for different temporal scales.


PubMed | Vascular Anesthesia and Intensive Care, Instituto Of Milan, Federal University of São Carlos and University of Milan
Type: | Journal: Physiological measurement | Year: 2017

We exploited a model-based Wiener-Granger causality method in the information domain for the evaluation of the transfer entropy (TE) and interaction TE (ITE), the latter taken as a measure of the net balance between redundancy and synergy, to describe the interactions between the spontaneous variability of heart period (HP) and systolic arterial pressure (SAP) and the effect of respiration (R) on both variables. Cardiac control was typified via the genuine TE from SAP to HP, that from R to HP, and the ITE from SAP and R to HP, while vascular control was characterized via the genuine TE from HP to SAP, that from R to SAP, and the ITE from HP and R to SAP. The approach was applied to study age-related modifications of cardiac and vascular controls in a cohort of 100 healthy humans (age from 21 to 70 years, 54 males) recorded at supine rest (REST) and during active standing (STAND). A surrogate approach was exploited to test the significance of the computed quantities. Trends of the genuine information transfer with age, already present in literature, were here confirmed. We originally found that: i) at REST redundancy was predominant over synergy in both vascular and cardiac controls; ii) the predominance of redundancy of the cardiac control was not affected by postural challenge, while STAND reduced redundancy of vascular control; iii) the net redundancy of the cardiac control at REST gradually decreased with age, while that of vascular control remained stable; iv) during STAND net redundancy of both cardiac and vascular controls was stable with age. The study confirms the relevance of computing genuine information transfer in cardiovascular control analysis and stresses the importance of evaluating the ITE to quantify the degree of redundancy of physiological mechanisms operating to maintain cardiovascular homeostasis.


Porta A.,University of Milan | Porta A.,IRCCS Galeazzi Orthopedic Institute | Bari V.,Vascular Anesthesia and Intensive Care | Marchi A.,Humanitas Clinical and Research Center | And 6 more authors.
Physiological Measurement | Year: 2015

The study compares permutation-based and coarse-grained entropy approaches for the assessment of complexity of short heart period (HP) variability recordings. Shannon permutation entropy (SPE) and conditional permutation entropy (CPE) are computed as examples of permutation-based entropies, while the k-nearest neighbor conditional entropy (KNNCE) is calculated as an example of coarse-grained conditional entropy. SPE, CPE and KNNCE were applied to ad-hoc simulated autoregressive processes corrupted by increasing amounts of broad band noise and to real HP variability series recorded after complete vagal blockade obtained via administration of a high dose of atropine (AT) in nine healthy volunteers and during orthostatic challenge induced by 90° head-up tilt (T90) in 15 healthy individuals. Over the simulated series the performances of SPE and CPE degraded more rapidly with the amplitude of the superimposed broad band noise than those of KNNCE. Over real data KNNCE identified the expected decrease of the HP variability complexity both after AT and during T90. Conversely SPE and CPE detected the decrease of HP variability complexity solely during T90 as a likely result of the more favorable signal-to-noise ratio during T90 than after AT. Results derived from both simulations and real data indicated that permutation-based entropies had a larger susceptibility to broad band noise than KNNCE. We recommend caution in applying permutation-based entropies in presence of short HP variability series characterized by a low signal-to-noise ratio. © 2015 Institute of Physics and Engineering in Medicine.


Porta A.,University of Milan | Faes L.,University of Trento | Marchi A.,Polytechnic of Milan | Marchi A.,San Gerardo Hospital | And 5 more authors.
Frontiers in Physiology | Year: 2015

A full decomposition of the predictive entropy (PE) of the spontaneous variations of the heart period (HP) given systolic arterial pressure (SAP) and respiration (R) is proposed. The PE of HP is decomposed into the joint transfer entropy (JTE) from SAP and R to HP and self-entropy (SE) of HP. The SE is the sum of three terms quantifying the synergistic/redundant contributions of HP and SAP, when taken individually and jointly, to SE and one term conditioned on HP and SAP denoted as the conditional SE (CSE) of HP given SAP and R. The JTE from SAP and R to HP is the sum of two terms attributable to SAP or R plus an extra term describing the redundant/synergistic contribution to the JTE. All quantities were computed during cardiopulmonary loading induced by -25° head-down tilt (HDT) via a multivariate linear regression approach. We found that: (i) the PE of HP decreases during HDT; (ii) the decrease of PE is attributable to a lessening of SE of HP, while the JTE from SAP and R to HP remains constant; (iii) the SE of HP is dominant over the JTE from SAP and R to HP and the CSE of HP given SAP and R is prevailing over the SE of HP due to SAP and R both in supine position and during HDT; (iv) all terms of the decompositions of JTE from SAP and R to HP and SE of HP due to SAP and R were not affected by HDT; (v) the decrease of the SE of HP during HDT was attributed to the reduction of the CSE of HP given SAP and R; (vi) redundancy of SAP and R is prevailing over synergy in the information transferred into HP both in supine position and during HDT, while in the HP information storage synergy and redundancy are more balanced. The approach suggests that the larger complexity of the cardiac control during HDT is unrelated to the baroreflex control and cardiopulmonary reflexes and may be related to central commands and/or modifications of the dynamical properties of the sinus node. © 2015 Porta, Faes, Marchi, Bari, De Maria, Guzzetti, Colombo and Raimondi.


PubMed | L Sacco Hospital Milan, Vascular Anesthesia and Intensive Care, Humanitas Clinical and Research Center Rozzano, Polytechnic of Milan and 3 more.
Type: | Journal: Frontiers in physiology | Year: 2015

A full decomposition of the predictive entropy (PE) of the spontaneous variations of the heart period (HP) given systolic arterial pressure (SAP) and respiration (R) is proposed. The PE of HP is decomposed into the joint transfer entropy (JTE) from SAP and R to HP and self-entropy (SE) of HP. The SE is the sum of three terms quantifying the synergistic/redundant contributions of HP and SAP, when taken individually and jointly, to SE and one term conditioned on HP and SAP denoted as the conditional SE (CSE) of HP given SAP and R. The JTE from SAP and R to HP is the sum of two terms attributable to SAP or R plus an extra term describing the redundant/synergistic contribution to the JTE. All quantities were computed during cardiopulmonary loading induced by -25 head-down tilt (HDT) via a multivariate linear regression approach. We found that: (i) the PE of HP decreases during HDT; (ii) the decrease of PE is attributable to a lessening of SE of HP, while the JTE from SAP and R to HP remains constant; (iii) the SE of HP is dominant over the JTE from SAP and R to HP and the CSE of HP given SAP and R is prevailing over the SE of HP due to SAP and R both in supine position and during HDT; (iv) all terms of the decompositions of JTE from SAP and R to HP and SE of HP due to SAP and R were not affected by HDT; (v) the decrease of the SE of HP during HDT was attributed to the reduction of the CSE of HP given SAP and R; (vi) redundancy of SAP and R is prevailing over synergy in the information transferred into HP both in supine position and during HDT, while in the HP information storage synergy and redundancy are more balanced. The approach suggests that the larger complexity of the cardiac control during HDT is unrelated to the baroreflex control and cardiopulmonary reflexes and may be related to central commands and/or modifications of the dynamical properties of the sinus node.


PubMed | Humanitas Clinical and Research Center, Vascular Anesthesia and Intensive Care, Polytechnic of Milan, Instituto Of Milan and 2 more.
Type: | Journal: Physiological measurement | Year: 2017

Cardioventilatory phase synchronization was studied in ten critically ill patients admitted in intensive care unit (ICU) for acute respiratory failure under two mechanical ventilatory modes: i) pressure controlled ventilation (PCV); ii) pressure support ventilation (PSV). The two modalities were administered to the same patient in different times in a random order. Cardioventilatory phase interactions were typified by plotting the relative position of a heartbeat, detected from the electrocardiogram and collected in n groups, within m ventilatory cycles as a function of the progressive cardiac beat number via the synchrogram. n:m phase synchronized patterns were detected by computing the variability of each phase group. The percent duration of the recording featuring phase synchronization was assessed as a measure of the strength of phase synchrony and tested against situations of full phase desynchronization between cardiac and ventilatory rhythms. Indexes quantifying the variability of the cardiac and ventilatory activities were computed as well. Findings proved that: i) a significant presence of n:m phase synchronized patterns was detected in PCV; ii) the strength of n:m phase synchronization was stronger during PCV than PSV; iii) different strengths of cardioventilatory phase synchronization detected during PCV and PSV were found in presence of similar heart and ventilatory rates and alike variability. We conclude that mechanical ventilation can induce a significant presence of cardioventilatory phase synchronized patterns and this amount depends on the mode of mechanical ventilation. Future studies should test the eventual link of the level of phase coordination between heart and mechanical ventilation to a clinical outcome to understand whether featuring a certain degree of cardioventilatory phase synchronization is beneficial for the critical patient in ICU.


Ranucci M.,Vascular Anesthesia and Intensive Care | Baryshnikova E.,Vascular Anesthesia and Intensive Care | Castelvecchio S.,Vascular Anesthesia and Intensive Care | Pelissero G.,Scientific Directorate
Annals of Thoracic Surgery | Year: 2013

Background: Postoperative bleeding is common after cardiac surgery. Major bleeding (MB) is a determinant of red blood cell (RBC) transfusion, especially in patients with preoperative anemia. Preoperative anemia and RBC transfusions are recognized risk factors for operative mortality. The present study investigates the role of MB as an independent determinant of operative mortality in cardiac surgery. Methods: A single-center retrospective study based on the institutional database of cardiac surgery in the period 2000-2012 was conducted. Sixteen thousand one hundred fifty-four (16,154) consecutive adult patients undergoing cardiac surgery were analyzed. The impact of postoperative bleeding and MB on operative (30 days) mortality was analyzed univariately and after correction for preoperative anemia, RBC transfusions, and other confounders. Results: Postoperative bleeding was significantly (p < 0.001) associated with operative mortality, both in univariate and multivariable models. The main complications associated with MB were thromboembolic complications, infections, and surgical reexploration. In a multivariable model, MB remained an independent predictor of operative mortality (odds ratio, 3.45; 95% confidence interval, 2.78 to 4.28). Preoperative anemia and RBC transfusions coexist in the model, acting with a multiplying effect when associated with MB. Conclusions: Major bleeding is per se a risk factor for operative mortality. However, its deleterious effects are strongly enhanced by RBC transfusions and, to a lesser extent, preoperative anemia. Major bleeding is a partially modifiable risk factor, and adequate preemptive and treatment strategies should be applied to limit this event. © 2013 The Society of Thoracic Surgeons.


PubMed | Vascular Anesthesia and Intensive Care
Type: Journal Article | Journal: Physiological reports | Year: 2014

During the coagulation process, blood changes from a liquid to a solid gel phase. These changes are reflected by changes in blood viscosity; however, blood viscosity at different shear rates (SR) has not been previously explored during the coagulation process. In this study, we investigated the viscosity changes of whole blood in 10 subjects with a normal coagulation profile, using a cone-on-plate viscosimeter. For each subject, three consecutive measurements were performed, at a SR of 20, 40, 80 sec(-1). On the basis of the time-dependent changes in blood viscosity, we identified the gel point (GP), the time-to-gel point (TGP), the maximum clot viscosity (MCV), and the clot lysis half-time (CLH). The TGP significantly (P = 0.0023) shortened for increasing SR, and was significantly associated with the activated partial thromboplastin time at a SR of 20 sec(-1) (P = 0.038) and 80 sec(-1) (P = 0.019). The MCV was significantly lower at a SR of 80 sec(-1) versus 40 sec(-1) (P = 0.027) and the CLH significantly (P = 0.048) increased for increasing SR. These results demonstrate that measurement of blood viscosity during the coagulation process offers a number of potentially useful parameters. In particular, the association between the TGP and the activated partial thromboplastin time is an expression of the clotting time (intrinsic and common pathway), and its shortening for increasing SR may be interpreted the well-known activating effects of SR on platelet activation and thrombin generation. Further studies focused on the TGP under conditions of hypo- or hypercoagulability are required to confirm its role in the clinical practice.

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