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Brložnik M, Lunka E, Avbelj V, Nemec Svete A, Domanjko Petrič A. Cardiac Electromechanical Activity in Healthy Cats and Cats with Cardiomyopathies. Sensors (Basel) 2023; 23:8336. [PMID: 37837166 PMCID: PMC10574989 DOI: 10.3390/s23198336] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2023] [Revised: 10/03/2023] [Accepted: 10/06/2023] [Indexed: 10/15/2023]
Abstract
Optimal heart function depends on perfect synchronization between electrical and mechanical activity. In this pilot study, we aimed to investigate the electromechanical activity of the heart in healthy cats and cats with cardiomyopathy with phonocardiography (PCG) synchronized to an electrocardiography (ECG) pilot device. We included 29 cats (12 healthy cats and 17 cats diagnosed with cardiomyopathy) and performed a clinical examination, PCG synchronized with ECG and echocardiography. We measured the following durations with the pilot PCG device synchronized with ECG: QRS (ventricular depolarization), QT interval (electrical systole), QS1 interval (electromechanical activation time (EMAT)), S1S2 (mechanical systole), QS2 interval (electrical and mechanical systole) and electromechanical window (end of T wave to the beginning of S2). The measured parameters did not differ between healthy cats and cats with cardiomyopathy; however, in cats with cardiomyopathy, EMAT/RR, QS2/RR and S1S2/RR were significantly longer than in healthy cats. This suggests that the hypertrophied myocardium takes longer to generate sufficient pressure to close the mitral valve and that electrical systole, i.e., depolarization and repolarization, and mechanical systoles are longer in cats with cardiomyopathy. The PCG synchronized with the ECG pilot device proved to be a valuable tool for evaluating the electromechanical activity of the feline heart.
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Affiliation(s)
- Maja Brložnik
- Faculty of Health Sciences, University of Ljubljana, 1000 Ljubljana, Slovenia;
- Small Animal Clinic, Veterinary Faculty, University of Ljubljana, 1000 Ljubljana, Slovenia; (E.L.); (A.N.S.)
| | - Ema Lunka
- Small Animal Clinic, Veterinary Faculty, University of Ljubljana, 1000 Ljubljana, Slovenia; (E.L.); (A.N.S.)
| | - Viktor Avbelj
- Department of Communication Systems, Jožef Stefan Institute, 1000 Ljubljana, Slovenia;
| | - Alenka Nemec Svete
- Small Animal Clinic, Veterinary Faculty, University of Ljubljana, 1000 Ljubljana, Slovenia; (E.L.); (A.N.S.)
| | - Aleksandra Domanjko Petrič
- Small Animal Clinic, Veterinary Faculty, University of Ljubljana, 1000 Ljubljana, Slovenia; (E.L.); (A.N.S.)
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Bregar K, Krištofelc T, Depolli M, Avbelj V, Rashkovska A. Power Autonomy Estimation of Low-Power Sensor for Long-Term ECG Monitoring. Sensors (Basel) 2022; 22:5070. [PMID: 35890750 PMCID: PMC9320243 DOI: 10.3390/s22145070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/30/2022] [Revised: 06/29/2022] [Accepted: 06/30/2022] [Indexed: 06/15/2023]
Abstract
The paper analyses the autonomy of a wireless body sensor that continuously measures the potential difference between two proximal electrodes on the skin, primarily used for measuring an electrocardiogram (ECG) when worn on the torso. The sensor is powered by a small rechargeable battery and is designed for extremely low power use. However, the autonomy of the sensor, regarding its power consumption, depends significantly on the measurement quality selection, which directly influences the amount of data transferred. Therefore, we perform an in-depth analysis of the power consumption sources, particularly those connected with the Bluetooth Low Energy (BLE) communication protocol, in order to model and then tune the autonomy of the wireless low-power body sensor for long-term ECG monitoring. Based on the findings, we propose two analytical models for power consumption: one for power consumption estimation in idle mode and the other one for power estimation in active mode. The proposed models are validated with the measured power consumption of the ECG sensor at different ECG sensor settings, such as sampling rate and transmit power. The proposed models show a good fit to the measured power consumption at different ECG sensor sampling rates. This allows for power consumption analysis and sensor autonomy predictions for different sensor settings. Moreover, the results show that the transmit power has a negligible effect on the sensor autonomy in the case of streaming data with high sampling rates. The most energy can be saved by lowering the sampling rate with suitable connection interval and by packing as much data as possible in a single BLE packet.
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Zivanovic I, Zupanic E, Avbelj V, Zibert J, Lainscak M, Kalisnik JM. Nonlinear Heart Rate Variability in Patients with Chronic Obstructive Pulmonary Disease and Changes after 4-week Comprehensive Inpatient Pulmonary Rehabilitation. Nonlinear Dynamics Psychol Life Sci 2022; 26:149-162. [PMID: 35366220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Cardiovascular disease is among the leading causes of mortality in chronic obstructive pulmonary disease (COPD). Nonlinear heart rate variability (NHRV) measures are markers and predictors of cardiovascular disease, particularly arrhythmias. Our aim was to investigate NHRV in patients with COPD and changes after pulmonary rehabilitation. 20-minute ECGs were used to compare NHRV (a) in 45 healthy individuals and 31 patients with COPD and (b) in 16 patients who completed rehabilitation versus 13 age- and sex-matched control patients. We studied detrended fluctuation analysis (DFA1, DFA2), fractal dimension (low, high, average FD) and sample entropy. Compared to healthy individuals, patients with COPD had lower DFA1 (p=.038). During rehabilitation high FD decreased (p=.018) and DFA2 increased (p=.043). Cluster analysis displayed an increase of DFA1 in the rehabilitation cluster with DFA1 values below 1 (p=.032). NHRV reflects altered autonomic regulation in patients with COPD. Reduced DFA1 in patients with COPD implies a stronger pro-arrhythmic substrate and altered parasympathetic modulation.
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Affiliation(s)
| | | | | | | | | | - Jurij Matija Kalisnik
- Paracelsus Medical Univeristy, Nuremberg, Germany and University of Ljubljana, Slovenia
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Rashkovska A, Depolli M, Tomašić I, Avbelj V, Trobec R. Medical-Grade ECG Sensor for Long-Term Monitoring. Sensors (Basel) 2020; 20:s20061695. [PMID: 32197444 PMCID: PMC7146736 DOI: 10.3390/s20061695] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 03/11/2020] [Accepted: 03/14/2020] [Indexed: 11/16/2022]
Abstract
The recent trend in electrocardiogram (ECG) device development is towards wireless body sensors applied for patient monitoring. The ultimate goal is to develop a multi-functional body sensor that will provide synchronized vital bio-signs of the monitored user. In this paper, we present an ECG sensor for long-term monitoring, which measures the surface potential difference between proximal electrodes near the heart, called differential ECG lead or differential lead, in short. The sensor has been certified as a class IIa medical device and is available on the market under the trademark Savvy ECG. An improvement from the user’s perspective—immediate access to the measured data—is also implemented into the design. With appropriate placement of the device on the chest, a very clear distinction of all electrocardiographic waves can be achieved, allowing for ECG recording of high quality, sufficient for medical analysis. Experimental results that elucidate the measurements from a differential lead regarding sensors’ position, the impact of artifacts, and potential diagnostic value, are shown. We demonstrate the sensors’ potential by presenting results from its various areas of application: medicine, sports, veterinary, and some new fields of investigation, like hearth rate variability biofeedback assessment and biometric authentication.
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Affiliation(s)
- Aleksandra Rashkovska
- Department of Communication Systems, Jožef Stefan Institute, Jamova cesta 39, 1000 Ljubljana, Slovenia; (M.D.); (V.A.); (R.T.)
- Correspondence: ; Tel.: +386-1-477-3701
| | - Matjaž Depolli
- Department of Communication Systems, Jožef Stefan Institute, Jamova cesta 39, 1000 Ljubljana, Slovenia; (M.D.); (V.A.); (R.T.)
| | - Ivan Tomašić
- Division of Intelligent Future Technologies, Mälardalen University, Högskoleplan 1, 721 23 Västerås, Sweden;
| | - Viktor Avbelj
- Department of Communication Systems, Jožef Stefan Institute, Jamova cesta 39, 1000 Ljubljana, Slovenia; (M.D.); (V.A.); (R.T.)
| | - Roman Trobec
- Department of Communication Systems, Jožef Stefan Institute, Jamova cesta 39, 1000 Ljubljana, Slovenia; (M.D.); (V.A.); (R.T.)
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Kališnik JM, Avbelj V, Vratanar J, Santarpino G, Geršak B, Fischlein T, Trobec R, Žibert J. Cardiac autonomic regulation and PR interval determination for enhanced atrial fibrillation risk prediction after cardiac surgery. Int J Cardiol 2019; 289:24-29. [PMID: 31072633 DOI: 10.1016/j.ijcard.2019.04.070] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Revised: 03/25/2019] [Accepted: 04/23/2019] [Indexed: 11/29/2022]
Abstract
BACKGROUND Changes in cardiac autonomic regulation and P-wave characteristics are associated with the occurrence of atrial fibrillation. The purpose of this study was to evaluate whether combined preoperative non-invasive determination of cardiac autonomic regulation and PR interval allows for the identification of patients at risk of new-onset atrial fibrillation after cardiac surgery. METHODS RR, PR and QT intervals, and linear and non-linear heart rate variability parameters from 20 min high-resolution electrocardiographic recordings were determined one day before surgery in 150 patients on chronic beta blockers undergoing elective coronary artery bypass grafting, aortic valve replacement, or both, electively. RESULTS Thirty-one patients (21%) developed postoperative atrial fibrillation. In the atrial fibrillation group, more arterial hypertension, a greater age, a higher EuroSCORE II, a higher heart rate variability index (pNN50: 9 ± 20 vs. 4 ± 10, p = 0.050), a short PR interval (156 ± 23 vs. 173 ± 31 ms; p = 0.011), and a reduced short-term scaling exponent of the detrended fluctuation analysis (DFA1, 0.96 ± 0.36 vs. 1.11 ± 0.30 ms; p = 0.032) were found compared to the sinus rhythm group. Logistic regression modeling confirmed PR interval, DFA1 and age as the strongest preoperative predictors of postoperative atrial fibrillation (area under the receiver operating characteristic curve = 0.804). CONCLUSIONS Patients developing atrial fibrillation after cardiac surgery presented with severe cardiac autonomic derangement and a short PR interval preoperatively. The observed state characterizes both altered heart rate regulation and arrhythmic substrate and is strongly related to an increased risk of postoperative atrial fibrillation.
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Affiliation(s)
- Jurij M Kališnik
- Department of Cardiovascular Surgery, University Medical Center, Ljubljana, Slovenia; Department of Cardiac Surgery, Cardiovascular Center, Klinikum Nuernberg-Paracelsus Medical University, Nuremberg, Germany.
| | - Viktor Avbelj
- Department of Communication Systems, Jozef Stefan Institute, Ljubljana, Slovenia.
| | - Jon Vratanar
- Department of Cardiovascular Surgery, University Medical Center, Ljubljana, Slovenia
| | - Giuseppe Santarpino
- Department of Cardiac Surgery, Cardiovascular Center, Klinikum Nuernberg-Paracelsus Medical University, Nuremberg, Germany; Department of Cardiac Surgery, Città di Lecce Hospital, GVM Care & Research, Lecce, Italy
| | - Borut Geršak
- Department of Cardiovascular Surgery, University Medical Center, Ljubljana, Slovenia
| | - Theodor Fischlein
- Department of Cardiac Surgery, Cardiovascular Center, Klinikum Nuernberg-Paracelsus Medical University, Nuremberg, Germany.
| | - Roman Trobec
- Department of Communication Systems, Jozef Stefan Institute, Ljubljana, Slovenia.
| | - Janez Žibert
- Faculty of Health Sciences, University of Ljubljana, Ljubljana, Slovenia.
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Kališnik J, Pollari F, Avbelj V, Žibert J, Čarman D, Cvetkovič T, Pfeiffer S, Fischlein T, Klokocovnik T. Novel High-Resolution and Wireless Continuous Smart ECG Monitoring Improves Postoperative Atrial Fibrillation Recognition and Reveals Preceding Subtle Cardiac Autonomic Modulation Changes. Thorac Cardiovasc Surg 2019. [DOI: 10.1055/s-0039-1678945] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- J. Kališnik
- Department of Cardiovascular Surgery, University Medical Center Ljubljana, Ljubljana, Slovenia
- Paracelsus Medical University - Klinikum Nürnberg, Herzchirurgie, Nürnberg, Germany
| | - F. Pollari
- Paracelsus Medical University - Klinikum Nürnberg, Herzchirurgie, Nürnberg, Germany
| | - V. Avbelj
- Department of Communication Systems, Jozef Stefan Institute, Ljubljana, Slovenia
| | - J. Žibert
- Faculty of Health Sciences, University of Ljubljana, Ljubljana, Slovenia
| | - D. Čarman
- Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - T. Cvetkovič
- Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - S. Pfeiffer
- Paracelsus Medical University - Klinikum Nürnberg, Herzchirurgie, Nürnberg, Germany
| | - T. Fischlein
- Paracelsus Medical University - Klinikum Nürnberg, Herzchirurgie, Nürnberg, Germany
| | - T. Klokocovnik
- Department of Cardiovascular Surgery, University Medical Center Ljubljana, Ljubljana, Slovenia
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Brložnik M, Likar Š, Krvavica A, Avbelj V, Domanjko Petrič A. Wireless body sensor for electrocardiographic monitoring in dogs and cats. J Small Anim Pract 2018; 60:223-230. [PMID: 30474218 DOI: 10.1111/jsap.12963] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2018] [Revised: 07/12/2018] [Accepted: 07/19/2018] [Indexed: 11/28/2022]
Abstract
OBJECTIVES To evaluate the diagnostic utility of electrocardiogram data obtained by a wireless sensor from 36 dogs and four cats with suspected arrhythmias caused by cardiac or systemic diseases. MATERIALS AND METHODS Wireless electrocardiographic recordings were obtained via two precordial electrodes attached to an electrocardiogram sensor connected to a smart device via low-power Bluetooth technology. Cardiac rate, rhythm and duration of P-QRS-T waves were evaluated with VisECG® software. Fifteen- to 30-minute wireless recordings were compared to standard electrocardiograms. Furthermore, the wireless sensor was used in 10 dogs and four cats for 24-hour continuous electrocardiogram monitoring at home. RESULTS When compared to standard electrocardiogram, equivalent results were obtained for heart rate and duration of different waves. Due to the longer recording time, more arrhythmias were diagnosed with the wireless device in 50% (15 of 30) of animals with arrhythmias. Satisfactory recordings were obtained when the dogs were resting, standing or walking but interpretation of the wireless electrocardiogram signal was not possible during strenuous physical activity. CLINICAL SIGNIFICANCE Wireless electrocardiographic monitoring is a reliable and accurate method for identification of heart rate, arrhythmia and duration of electrocardiogram waves. A higher diagnostic yield of arrhythmias was documented with the wireless sensor due to prolonged monitoring. The device offers a good option for the long-term monitoring of canine and feline cardiac rhythm.
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Affiliation(s)
- M Brložnik
- Clinic for Small Animals, Veterinary Faculty, University of Ljubljana, Ljubljana 1000, Slovenia
| | - Š Likar
- Clinic for Small Animals, Veterinary Faculty, University of Ljubljana, Ljubljana 1000, Slovenia
| | - A Krvavica
- Clinic for Small Animals, Veterinary Faculty, University of Ljubljana, Ljubljana 1000, Slovenia
| | - V Avbelj
- Department of Communication Systems, Jožef Stefan Institute, Ljubljana 1000, Slovenia
| | - A Domanjko Petrič
- Clinic for Small Animals, Veterinary Faculty, University of Ljubljana, Ljubljana 1000, Slovenia
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Kalisnik J, Avbelj V, Vratanar J, Santarpino G, Zibert J, Fischlein T. Novel Postoperative Atrial Fibrillation Risk Prediction from Preoperative High-Resolution ECG-Based Assessment of Nonlinear Heart Rate Dynamics. Thorac Cardiovasc Surg 2017. [DOI: 10.1055/s-0037-1598914] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
| | - V. Avbelj
- Jožef Stefan Institute, Ljubliana, Slovenia
| | - J. Vratanar
- University Medical Center, Ljubliana, Slovenia
| | | | - J. Zibert
- University of Ljubljana, Ljubliana, Slovenia
| | - T. Fischlein
- Paracelsus Medical University, Nürnberg, Germany
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Švigelj V, Šinkovec M, Avbelj V, Trobec R, Gaspar L, Petrovič D, Kruzliak P. Cardiovagal and adrenergic function tests in unilateral carotid artery stenosis patients-a Valsalva manoeuvre tool to show an autonomic dysfunction? Wien Klin Wochenschr 2016; 128:504-12. [PMID: 26980215 DOI: 10.1007/s00508-016-0980-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2015] [Accepted: 02/18/2016] [Indexed: 10/22/2022]
Abstract
BACKGROUND The stability of an arterial baroreflex depends also upon the integrity of the afferent limb. For its quantification, we can use a noninvasive test such as baroreceptor sensitivity estimation during Valsalva manoeuvre. The aim of this study was to evaluate potential autonomic dysfunction in patients with unilateral severe carotid disease and compare the results to the results obtained from an age and gender matched group of healthy volunteers. METHODS We evaluated dynamic changes during Valsalva manoeuvre (Valsalva ratio, cardiovagal and adrenergic baroreceptor sensitivity, sympathetic indexes and its dynamic ranges) in 41 patients (29 males; 62.9 ± 7.4 years) and compared the results to results obtained from volunteers (62.8 ± 7.0 years). RESULTS Valsalva ratio between the patients and control group revealed no significant difference, as well as cardiovagal and adrenergic baroreceptor sensitivity. Sympathetic indexes, except for sympathetic index 2, reflecting the sympathetic vasoconstrictor baroreceptor response in late phase 2 of Valsalva manoeuvre (7.1 ± 13.1 mmHg in patients vs. 11.4 ± 10.2 mmHg in control group; p = 0.012) showed no significant differences between the studied groups. The most prominent dynamic range between the groups was within the sympathetic index 2. CONCLUSION With some Valsalva manoeuvre test results, we were not able to show severe autonomic dysfunction in unilateral severe carotid stenosis patients except for lower vasoconstriction response within the late phase 2 of the manoeuvre.
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Affiliation(s)
- Viktor Švigelj
- Division of Neurology, Department of Vascular Neurology and Neurological Intensive Care, Neurological Intensive Care Unit, University Medical Centre Ljubljana, Zaloška 2, 1525, Ljubljana, Slovenia.
| | - Matjaž Šinkovec
- Division of Internal Medicine, Department of Cardiology, University Medical Centre Ljubljana, Zaloška 2, 1525 Ljubljana, Slovenia
| | - Viktor Avbelj
- Department of Communication Systems, Jožef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia
| | - Roman Trobec
- Department of Communication Systems, Jožef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia
| | - Ludovit Gaspar
- 2nd Department of Internal Medicine, Faculty of Medicine, Comenius University and University Hospital, Mickiewiczova 13, 813 69, Bratislava, Slovak Republic
| | - Daniel Petrovič
- Institute of Histology and Embryology, Faculty of Medicine, University of Ljubljana, Korytkova 2, 1000 Ljubljana, Slovenia
| | - Peter Kruzliak
- 2nd Department of Internal Medicine, Faculty of Medicine, Masaryk University, Pekarska 53, 656 91, Brno, Czech Republic.,Laboratory of Structural Biology and Proteomics, Faculty of Pharmacy, University of Veterinary Medicine and Pharmaceutical Sciences, Brno, Czech Republic
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Kališnik JM, Hrovat E, Hrastovec A, Avbelj V, Žibert J, Geršak B. Severe Cardiac Autonomic Derangement and Altered Ventricular Repolarization Pave the Way to Postoperative Atrial Fibrillation. Innovations 2015. [DOI: 10.1177/155698451501000606] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Jurij Matija Kališnik
- Department of Cardiovascular Surgery, University Medical Center, Ljubljana, Slovenia
- Department of Cardiac Surgery, Cardiovascular Center, Klinikum Nuernberg, Paracelsus Medical University, Nuremberg, Germany
| | - Eva Hrovat
- Department of Cardiovascular Surgery, University Medical Center, Ljubljana, Slovenia
| | - Alenka Hrastovec
- Department of Anesthesiology and Intensive Care, University Medical Center, Ljubljana, Slovenia
| | - Viktor Avbelj
- Department of Communications and Computer Networks, Jožef Stefan Institute, Ljubljana, Slovenia
| | - Janez Žibert
- Faculty of Health Sciences, University of Ljubljana, Ljubljana, Slovenia
| | - Borut Geršak
- Department of Cardiovascular Surgery, University Medical Center, Ljubljana, Slovenia
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Švigelj V, Šinkovec M, Avbelj V, Trobec R. Simple cardiovagal and adrenergic function tests in carotid artery stenosis patients as a potential tool for determining a transient autonomic dysfunction. Clin Auton Res 2015; 25:383-90. [PMID: 26374301 DOI: 10.1007/s10286-015-0316-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2014] [Accepted: 08/24/2015] [Indexed: 11/24/2022]
Abstract
PURPOSE The arterial baroreflex depends on the integrity of the afferent limb, which can be quantified using the baroreceptor's sensitivity (BRS) during the Valsalva maneuver (VM). The aim of this study was to evaluate, using autonomic nervous system tests, the autonomic function in patients after a carotid artery angioplasty (CAS). METHODS We evaluated the changes in blood pressure (BP) during the VM (Valsalva ratio, BRS, sympathetic indexes) in 41 patients with symptomatic, unilateral, internal carotid artery stenosis. RESULTS The Valsalva ratio between the baseline and the post-procedural day (1.3 ± 0.1 vs 1.44 ± 0.3; P = 0.002) and the post-procedural day and a month later (1.44 ± 0.3 vs 1.3 ± 0.3; P = 0.0002) revealed significant differences. This was confirmed with a cardiovagal BRS test. However, the adrenergic BRS did not reveal any differences. Sympathetic indexes [BP fall (SI1) and recovery during phase 2 (SI2)] showed differences for the periods before and a day after the treatment (36.9 ± 18.0 vs 27.2 ± 21.4 and 7.1 ± 13.1 vs 3.0 ± 8.2, respectively; P = 0.004) and for SI1 a day and a month after the treatment (27.2 ± 21.4 vs 37.1 ± 21.8; P = 0.036). The dynamic ranges between S1 and S3 (the difference in the BP between the baseline and the end of phase 2) were also different (P = 0.007 and P = 0.044, respectively). CONCLUSION We found heterogeneous responses in the BP regulation obtained with the Valsalva maneuver in our patients; however, we could not confirm that CAS provoked any long-term autonomic dysfunction, except for 1 day after the procedure.
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Affiliation(s)
- Viktor Švigelj
- Neurological Intensive Care Unit, Division of Neurology, Department of Vascular Neurology and Intensive Care, University Medical Centre Ljubljana, Zaloška 2, 1525, Ljubljana, Slovenia.
| | - Matjaž Šinkovec
- Division of Internal Medicine, Department of Cardiology, University Medical Centre Ljubljana, Zaloška 7, 1525, Ljubljana, Slovenia
| | - Viktor Avbelj
- Department of Communication Systems, Jožef Stefan Institute, Jamova 39, 1000, Ljubljana, Slovenia
| | - Roman Trobec
- Department of Communication Systems, Jožef Stefan Institute, Jamova 39, 1000, Ljubljana, Slovenia
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Tomasic I, Avbelj V, Trobec R. Smart wireless sensor for physiological monitoring. Stud Health Technol Inform 2015; 211:295-301. [PMID: 25980886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Presented is a wireless body sensor capable of measuring local potential differences on a body surface. By using on-sensor signal processing capabilities, and developed algorithms for off-line signal processing on a personal computing device, it is possible to record single channel ECG, heart rate, breathing rate, EMG, and when three sensors are applied, even the 12-lead ECG. The sensor is portable, unobtrusive, and suitable for both inpatient and outpatient monitoring. The paper presents the sensor's hardware and results of power consumption analysis. The sensor's capabilities of recording various physiological parameters are also presented and illustrated. The paper concludes with envisioned sensor's future developments and prospects.
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Rashkovska A, Trobec R, Avbelj V, Veselko M. Knee temperatures measured in vivo after arthroscopic ACL reconstruction followed by cryotherapy with gel-packs or computer controlled heat extraction. Knee Surg Sports Traumatol Arthrosc 2014; 22:2048-56. [PMID: 23877725 DOI: 10.1007/s00167-013-2605-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/10/2012] [Accepted: 07/04/2013] [Indexed: 10/26/2022]
Abstract
PURPOSE To obtain in vivo data about intra- and extra-articular knee temperatures to assess the effectiveness of two cryotherapeutic methods-conventional cooling with gel-packs and computer controlled cryotherapy following anterior cruciate ligament (ACL) reconstructive surgery. METHODS Twenty patients were arbitrarily assigned for cryotherapy after ACL reconstruction: 8 patients with frozen gel-packs and 12 patients with computer controlled cryotherapy with constant temperatures of the cooling liquid in the knee pads. The treatment was performed for 12 h. Temperatures were measured with two thermo sensors in catheters placed intraarticularly and subcutaneously, four sensors on the skin and one sensor under protective bandage, every second for 16 h after surgery. RESULTS In the first 2 h of treatment, there were no significant differences (n.s.) between the groups in temperatures in the intracondylar notch. After 4 h of cryotherapy, the temperatures were significantly lower on the skin (24.6 ± 2.8 and 31.4 ± 1.3 °C, p < 0.01) and in the subcutaneous tissue (28.6 ± 5.7 and 34.6 ± 1.4 °C, p = 0.01), and the difference between the temperature in the intracondylar notch and the subcutaneous tissue was significantly greater (4.0 ± 3.0 and 0.8 ± 0.6 °C, p = 0.01) in the computer controlled cryotherapy group compared to the gel-pack group. CONCLUSIONS The cooling effect of the arthroscopy irrigation fluid on the knee temperature is evident in the first 2 h of treatment. The energy extraction is significantly more effective and controllable by computer controlled cryotherapy than with frozen gel-packs. LEVEL OF EVIDENCE Prospective comparative study, Level II.
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Affiliation(s)
- Aleksandra Rashkovska
- Department of Communication Systems, Jožef Stefan Institute, Jamova 39, 1000, Ljubljana, Slovenia
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Zupanic E, Zivanovic I, Kalisnik JM, Avbelj V, Lainscak M. The Effect of 4-week Rehabilitation on Heart Rate Variability and QTc Interval in Patients with Chronic Obstructive Pulmonary Disease. COPD 2014; 11:659-69. [DOI: 10.3109/15412555.2014.898046] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Kalisnik JM, Hrastovec A, Avbelj V, Gersak B. Altered electrophysiological properties and deranged cardiac autonomic modulation predispose patients to atrial fibrillation after arrested heart operations. J Cardiothorac Surg 2013. [PMCID: PMC3844772 DOI: 10.1186/1749-8090-8-s1-o62] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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Ksela J, Kalisnik JM, Avbelj V, Gersak B. Multifractality of the heartbeat dynamics after beating heart myocardial revascularization. J Cardiothorac Surg 2013. [PMCID: PMC3844585 DOI: 10.1186/1749-8090-8-s1-o109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Avbelj V, Trobec R. A closer look at electrocardiographic P waves before and during spontaneous cardioinhibitory syncope. Int J Cardiol 2013; 166:e59-61. [DOI: 10.1016/j.ijcard.2013.01.063] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2012] [Accepted: 01/18/2013] [Indexed: 11/17/2022]
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Abstract
We propose a new body sensor for extracting the respiration rate based on the amplitude changes in the body surface potential differences between two proximal body electrodes. The sensor could be designed as a plaster-like reusable unit that can be easily fixed onto the surface of the body. It could be equipped either with a sufficiently large memory for storing the measured data or with a low-power radio system that can transmit the measured data to a gateway for further processing. We explore the influence of the sensor's position on the quality of the extracted results using multi-channel ECG measurements and considering all the pairs of two neighboring electrodes as potential respiration-rate sensors. The analysis of the clinical measurements, which also include reference thermistor-based respiration signals, shows that the proposed approach is a viable option for monitoring the respiration frequency and for a rough classification of breathing types. The obtained results were evaluated on a wireless prototype of a respiration body sensor. We indicate the best positions for the respiration body sensor and prove that a single sensor for body surface potential difference on proximal skin electrodes can be used for combined measurements of respiratory and cardiac activities.
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Affiliation(s)
- Roman Trobec
- Jožef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia.
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Ksela J, Kalisnik JM, Avbelj V, Suwalski P, Suwalski G, Gersak B. Ventricular arrhythmic disturbances and autonomic modulation after beating-heart revascularization in patients with pulmonary normotension. Wien Klin Wochenschr 2009; 121:324-9. [PMID: 19562295 DOI: 10.1007/s00508-009-1183-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
BACKGROUND De-novo ventricular arrhythmias are potentially life-threatening complications after beating-heart revascularization (off-pump CABG). Whether pulmonary hypertension can influence initiation of ventricular arrhythmias through increased sympathetic activity is controversial. In order to determine the influence of pulmonary hypertension on its relative contribution to ventricular arrhythmia, we first had to define the role of cardiac autonomic modulation in patients with pulmonary normotension. We aimed to observe how parameters of linear and nonlinear heart rate variability are changed pre- and postoperatively in patients with pulmonary normotension undergoing off-pump CABG. METHODS Fifteen-minute ECG recordings were collected before and after off-pump CABG in 54 patients with multivessel coronary artery disease and pulmonary normotension to determine linear (TP, HF, LF, LF:HF ratio) and nonlinear detrended fluctuation analysis (alpha1, alpha2) and fractal dimension (average, high and low) parameters of heart rate variability. Arrhythmia was monitored preoperatively in 24-hour Holter recordings and postoperatively by continuous monitoring and clinical assessment. RESULTS Deterioration from simple (Lown I-II) to complex (Lown III-V) ventricular arrhythmia was observed in 19 patients, and improvement from complex to simple arrhythmia in five patients (P = 0.022). Patients with postoperative deterioration of ventricular arrhythmia had preoperatively significantly lower values of TP, HF and LF (P = 0.024-0.043) and postoperatively significantly higher values on the low fractal dimension index (P = 0.031) than patients with postoperative improvement of arrhythmia. CONCLUSION Patients experiencing postoperative deterioration of ventricular arrhythmia already have impaired autonomic regulation before surgery. Higher postoperative values on the low fractal dimension index indicate that sympathetic predominance with or without concomitant vagal withdrawal is the underlying neurogenic mechanism contributing to ventricular arrhythmia.
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Affiliation(s)
- Jus Ksela
- Department of Cardiac Surgery, University Clinical Center Maribor, Slovenia
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Ksela J, Suwalski P, Kalisnik JM, Avbelj V, Suwalski G, Gersak B. Assessment of nonlinear heart rate dynamics after beating-heart revascularization. Heart Surg Forum 2009; 12:E10-6. [PMID: 19233759 DOI: 10.1532/hsf98.20081116] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND Advanced nonlinear methods of measuring heart rate variability (HRV) derived from the mathematics of complex dynamics and fractal geometry have provided new insights into the abnormalities of heart rate behavior in various pathologic conditions. These methods have provided additional prognostic information compared with traditional HRV measures and clearly have complemented the conventional linear methods. Knowledge about the behavior of complex cardiac dynamics indices after different cardiac procedures is very limited, however. We aimed to clarify how nonlinear heart rate dynamics are affected by beating-heart revascularization (off-pump coronary artery bypass graft [CABG] surgery) within the first week after the procedure. METHODS Included in the study were 66 patients who had isolated stable multivessel coronary artery disease and were in normal sinus rhythm. The patients were on chronic beta-blocker therapy and were scheduled for off-pump CABG. We performed 15-minute high-resolution electrocardiographic recordings preoperatively and on the third and seventh postoperative days to assess linear and nonlinear heart rate dynamics. Frequency-domain measurements, detrended fluctuation analysis (DFA) with short-term (<or=11 beats, alpha1) and long-term (>11 beats, alpha2) correlation properties of RR-intervals, and fractal dimension (FD) measurements (average, high, and low) were made. Arrhythmia was monitored preoperatively with 24-hour Holter recordings, postoperatively by continuous monitoring for the first 4 days after the procedure, and subsequently by clinical monitoring; 24-hour Holter recordings were obtained again on the seventh postoperative day. We used the paired-samples Student t test, the Mann-Whitney U test, and the Fisher exact test for statistical analyses. Differences in arrhythmia occurrence before and after the procedure were tested with the Wilcoxon signed rank test and the McNemar test. A P level < .05 was considered statistically significant. RESULTS Values for all frequency-domain parameters decreased significantly after off-pump CABG (P< .001). Values for the alpha1 and high FD parameters decreased significantly after the procedure (P= .028 and .001, respectively), whereas alpha2 increased significantly (P= .023). DFA alpha1 was significantly lower in patients with postoperative atrial fibrillation than in patients remaining in sinus rhythm (mean +/- SD, 0.79+/-0.32 versus 1.13+/-0.45 [P= .003] on the third postoperative day; 0.89+/-0.31 versus 1.22+/-0.34 [P< .001] on the seventh postoperative day), whereas low and average FDs were significantly higher (1.84+/-0.16 versus 1.68+/-0.19 [P= .003] on the third postoperative day and 1.77+/-0.18 versus 1.66+/-0.17 [P= .01] on the seventh postoperative day for the low FD; 1.83+/-0.09 versus 1.76+/-0.10 [P= .011] on the third postoperative day and 1.80+/-0.11 versus 1.73+/-0.10 [P= .014] on the seventh postoperative day for the average FD). The low FD was significantly higher on the third postoperative day in patients with postoperative deterioration of ventricular ectopy than in patients with improved ventricular ectopy (1.74+/-0.17 versus 1.48+/-0.08, [P= .03]). CONCLUSION The decreases in alpha1, average FD, and high FD indicate that a profound decay of cardiac complexity and fractal correlation can be observed after off-pump CABG. Furthermore, a more extensive impairment of nonlinear indices was observed in patients who developed postoperative arrhythmias than in those who remained in stable sinus rhythm. Our findings suggest that the postoperative hyperadrenergic setting acts as a preliminary condition in which both reduced and enhanced vagal activity may predispose patients to arrhythmia, indicating that postoperative rhythm disturbances are an end point associated with divergent autonomic substrates.
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Affiliation(s)
- Jus Ksela
- Department of Cardiac Surgery, University Clinical Centre Maribor, Maribor, Slovenia
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Kalisnik JM, Avbelj V, Trobec R, Vidmar G, Troise G, Gersak B. Ventricular repolarization dynamicity and arrhythmic disturbances after beating-heart and arrested-heart revascularization. Heart Surg Forum 2009; 11:E194-201. [PMID: 18782696 DOI: 10.1532/hsf98.20081025] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND Arrhythmias attributable to altered autonomic modulation of the heart, with elevated sympathetic and depressed vagal modulation, occur to a similar extent after surgery performed on beating or arrested hearts. Coronary artery bypass grafting (CABG) with cardiopulmonary bypass has been associated with more frequent occurrence of arrhythmic events than surgery performed without CABG, even with comparable levels of postoperative cardiac autonomic (dis) regulation after arrested- and beating-heart revascularization. We explored the effects of arrested- and beating-heart revascularization procedures on the dynamics of ventricular repolarization and on increased postoperative arrhythmic events. METHODS Study participants included 57 CABG patients; 28 underwent on-pump and 29 underwent off-pump procedures. The 2 groups were comparable regarding clinical and postoperative characteristics. With high-quality 15-minute digital electrocardiograms, we assessed ventricular repolarization dynamics using RR and QT intervals and analyzed QT variability (QTV) and QT-RR interdependence. RR and QT intervals were determined from stationary 5-minute segments. QT-interval variability was determined by a T-wave template-matching algorithm. We used linear regression to compute the slope/correlation of the QT/RR interval. The Fisher exact test, nonpaired t-test, and ANOVA were applied to test the results; P <.05 was considered significant. RESULTS Postoperative arrhythmic events were significantly more frequent in both groups. One week postoperatively these events were significantly more frequent in the on-pump group. In both groups, the RR interval was shorter after CABG (P <.001). The QT variability index increased from -1.2 + or - 0.6 to -0.8 + or - 0.4 after off-pump CABG and from -1.3 + or - 0.5 to -0.5 + or - 0.6 on day 4 after surgery (P <.05), further deteriorating to -0.2 + or - 0.6 one week after CABG in the on-pump group only (P <.05). QT-RR correlations decreased from 0.39 to 0.24 in the off-pump vs 0.34 to 0.17 in the on-pump group (P <.05), and in both groups they remained significantly reduced for as long as 4 weeks after CABG. CONCLUSIONS For both on- and off-pump CABG, beat-to-beat heart-rate changes and rate-dependent ventricular repolarization adaptation showed disparities that worsened after surgery. The observed repolarization lability after CABG procedures seems to be transient but more pronounced after on-pump CABG. The association of arrhythmic events with ventricular repolarization lability changes in the setting of faster heart rates offers novel insights into the mechanisms of perioperative proarrhythmia after beating- and arrested-heart revascularization.
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Affiliation(s)
- Jurij M Kalisnik
- Department of Cardiovascular Surgery, University Medical Center, Ljubljana, Slovenia.
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Ksela J, Kalisnik JM, Avbelj V, Vidmar G, Suwalski P, Suwalski G, Suwalski K, Gersak B. Short- versus long-term ECG recordings for the assessment of non-linear heart rate variability parameters after beating heart myocardial revascularization. Comput Biol Med 2009; 39:79-87. [DOI: 10.1016/j.compbiomed.2008.11.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2008] [Accepted: 11/24/2008] [Indexed: 11/28/2022]
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Abstract
OBJECTIVE Several hypotheses for the origin of the U wave in electrocardiograms have been proposed. We have set out to explore and test alternative modes for U-wave genesis via computer simulations. METHODS AND RESULTS A spatial model of a left ventricle has been constructed from 12 layers composed of cubic cells. Each cell is assigned its own time-dependent action potential with its own contribution to the electrical potential at arbitrary points where ECGs are measured. Simulated ECGs show that U waves can be generated using various combinations of action potentials (APs) across the different layers of the ventricular wall. We demonstrate a new mode of U-wave genesis, even with small differences in the repolarization. CONCLUSION The U wave can be generated in the presence of strong intercellular coupling. Myocardial layers with prolonged action potentials, like M cells, are not necessarily needed for U-wave genesis.
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Affiliation(s)
- Matjaz Depolli
- Department of Communication Systems, Jozef Stefan Institute, Ljubljana, Slovenia.
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Kalisnik JM, Avbelj V, Trobec R, Ivaskovic D, Vidmar G, Troise G, Gersak B. Effects of Beating- versus Arrested-Heart Revascularization on Cardiac Autonomic Regulation and Arrhythmias. Heart Surg Forum 2007; 10:E279-87. [PMID: 17599875 DOI: 10.1532/hsf98.20071055] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND Altered autonomic regulation after cardiac operations precipitates cardiac arrhythmias, affects repolarization, and increases the risk of sudden cardiac death. We sought to clarify how the 2 different techniques of coronary artery bypass grafting (CABG), namely conventional CABG using cardiopulmonary bypass (on-pump) and beating-heart CABG without cardiopulmonary bypass (off-pump), affect cardiac autonomic regulation and arrhythmic disturbances postoperatively. METHODS We included 57 consecutive patients, 28 in the on-pump group and 29 in the off-pump group. The electro-cardiographic recordings were performed on the preoperative day and the fourth, seventh, and twenty-eighth day after operation. Fifteen-minute digital recordings were taken; one channel was used to record electrocardiogram and the other breathing. Detailed analyses of arrhythmia, heart rate, and heart rate variability indices were performed on respective days to assess sympathetic and parasympathetic modulation of the heart and relate it to detected arrhythmic disturbances. RESULTS Total power, low-frequency power, which indicates baroreceptor-mediated sympathetic modulation, and high-frequency power, indicating parasympathetic vagal modulation, declined significantly in both groups after CABG (P < .001); however, 7 days after CABG, total and high-frequency power were better preserved in the off-pump group. Mean RR interval was longer in the off-pump group at 7 (P= .006) and 28 days (P= .008) after surgery. The total incidence of arrhythmic events was higher in the on-pump group on the seventh day (P = .017, adjusted odds ratio = 8.6, 95% confidence interval 1.4-80.3). CONCLUSIONS The results show profound impairment of cardiac autonomic regulation after CABG, showing better preserved cardiac autonomic modulation 7 days after beating-heart revascularization. Evidence suggests that slower restoration of heart rate and increased incidence of arrhythmic events after CABG using cardiopulmonary bypass are the result not only of impaired cardiac autonomic regulation but also of the involvement of additional factors of nonautonomic origin.
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Affiliation(s)
- Jurij M Kalisnik
- Department of Cardiovascular Surgery, University Medical Center Ljubljana, Ljubljana, Slovenia.
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26
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Abstract
Reduced cardiac vagal modulation increases propensity to arrhythmias. Right decubitus position is a vagal enhancer in coronary and congestive heart disease. We evaluated vagal modulation before and after coronary artery bypass grafting (CABG) in 30 patients. Heart rate variability (HRV) indexes in frequency domain were calculated from 10-min digital electrocardiograms. Kolmogorov-Smirnov and paired t-tests were applied, p<0.05 was considered significant. The HRV indexes decreased after CABG. Higher LF/HF ratio and shorter mean RR were observed in right recumbent position postoperatively. Right lateral decubitus position did not give rise to higher vagal modulation after heart surgery.
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Affiliation(s)
- Jurij-Matija Kalisnik
- Department of Cardiovascular Surgery, University Medical Center, Zaloska 7, SI-1000 Ljubljana, Slovenia.
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Kalisnik JM, Avbelj V, Trobec R, Ivaskovic D, Vidmar G, Troise G, Gersak B. Assessment of cardiac autonomic regulation and ventricular repolarization after off-pump coronary artery bypass grafting. Heart Surg Forum 2006; 9:E661-7. [PMID: 16753938 DOI: 10.1532/hsf98.2006-1020] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND Altered autonomic regulation precipitates cardiac arrhythmias and increases the risk of sudden cardiac death. This risk is further increased by changes in ventricular repolarization. Autonomic regulation is deranged in patients after myocardial on-pump revascularization. We aimed to clarify how off-pump coronary artery bypass grafting (CABG) affects postoperative cardiac autonomic regulation and ventricular repolarization within 4 weeks after CABG. METHODS Forty-two patients (mean age, 61.9 +/- 9.3 years; mean EURO score 2.6 +/- 1.9) were electively admitted for off-pump CABG. The electrocardiographic and respiratory waveform recordings were performed in the afternoon in the supine position for 10 minutes. Autonomic modulation was assessed using heart rate variability analysis. Power spectra were computed from 5-minute stable RR intervals using Fourier Transform analysis. Total power of spectra was defined in the range of 0.01 to 0.40 Hz, high-frequency power within 0.15 to 0.40 Hz, and low-frequency power within 0.04 to 0.15 Hz. Normalized power was defined as a ratio of power in each band/total power. The high- and low-frequency power as well as their normalized values indicated cardiac vagal and sympathetic modulation, respectively. Ventricular repolarization was assessed using QT interval, QT interval variability, and QT-RR interdependence analysis. QT intervals were determined from the beginning of the 5-minute segments. QT interval variability was evaluated by a T-wave template-matching algorithm. Pearson correlation between length of RR and QT interval was applied to study QT-RR characteristics. The results were tested for significance using the Fisher exact test, nonpaired t test, and analysis of variance; a P <.05 was considered significant. RESULTS The frequency of arrhythmic events and heart rate increased from the fourth to the seventh postoperative day and returned to preoperative levels 4 weeks after CABG. Heart rate variability measures indicating autonomic modulation remained depressed even 4 weeks after the procedure. QT variability index increased from -1.2 +/- 0.5 to -0.8 +/- 0.4 on the fourth day after the operation (P <.05) and returned to -1.0 +/- 0.5 4 weeks after CABG (P = not significant). QT-RR correlation decreased from 0.41 to 0.23 (P <.05) and remained significantly impaired as long as 4 weeks after CABG. CONCLUSIONS Observed faster heart rates until 1 week after off-pump CABG imply excessive adrenergic activation, which is comparable to on-pump CABG procedure rates. The results indicate profound autonomic derangement and loss of rate-dependent regulation after off-pump CABG even 4 weeks after operation. Restituted repolarization as assessed by QT variability index 4 weeks postoperatively corresponded with decreased frequency of rhythm disturbances 4 weeks after CABG. The loss of coupling between QT and RR intervals shows increased electrical instability postoperatively, which may serve as an additional promoter for postoperative arrhythmias, especially at higher heart rates.
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Affiliation(s)
- Jurij M Kalisnik
- Department of Cardiovascular Surgery, University Medical Center Ljubljana, Ljubljana, Slovenia.
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Lovric SS, Avbelj V, Trobec R, Zorman D, Rakovec P, Hojker S, Gersak B, Milcinski M. Sympathetic reinnervation after heart transplantation, assessed by iodine-123 metaiodobenzylguanidine imaging, and heart rate variability. Eur J Cardiothorac Surg 2004; 26:736-41. [PMID: 15450565 DOI: 10.1016/j.ejcts.2004.07.025] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2004] [Revised: 06/24/2004] [Accepted: 07/07/2004] [Indexed: 01/07/2023] Open
Abstract
OBJECTIVE Complete allograft denervation occurs during heart transplantation. Partial ventricular sympathetic reinnervation may develop one year or later after transplantation and can be measured with iodine-123-meta-iodobenziylguanidine (MIBG) uptake. Aim of this study was to assess sinus node sympathetic reinnervation measured with heart rate variability and ventricular sympathetic reinnervation evaluated with MIBG. METHODS Twelve patients and 14 healthy controls were included. In patients, MIBG scintigraphy with early and late imaging was performed. Heart to mediastinum ratio (HMR) was calculated and patients were divided in groups with (HMR>1.3) and without left ventricular reinnervation (HMR<1.3). Bipolar ECG with high sampling rate and resolution was recorded over 8.5 min in supine position and in upright position after 10 min interval. R-R intervals in time domain and heart rate variability in frequency domain through spectral power analysis of R-R intervals were analysed to evaluate sinus node reinnervation. Spectral power in low frequency range (0.04-0.15 Hz) above 4.5 ms(2) was considered as sinus node sympathetic reinnervation. RESULTS Six (50%) patients had evidence of left ventricular sympathetic reinnervation on scintigraphy. Sinus node sympathetic reinnervation based on heart rate variability was detected in 6 (50%) patients in supine, and in 4 (33%) patients in upright body position. Four patients groups were discerned: (1) with ventricular and sinus node sympathetic reinnervation, (2) with sinus node sympathetic reinnervation, (3) with ventricular sympathetic reinnervation and (4) without atrial or ventricular sympathetic reinnervation. Ventricular reinnervation process was time dependent and sinus node reinnervation was not. CONCLUSIONS Simultaneous ventricular sympathetic reinnervation assessed by MIBG and sinus node sympathetic reinnervation assessed by heart rate variability in supine as in upright position were detected only in two patients (17%). The results of our study show that eventual sinus node sympathetic reinnervation and left ventricular sympathetic reinnervation do not occur simultaneously.
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Affiliation(s)
- Silvia Samarin Lovric
- Department of Cardiology, University Medical Centre, Zaloska 7, Ljubljana, SI 1000, Slovenia.
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Abstract
The repolarisation variability in body surface electrocardiograms has been evaluated by beat-to-beat QT interval variability. Interpolated R-peak time and template T-wave matching algorithms were used to determine the characteristic time points of the R-wave and T-wave, respectively. The T-wave time can be determined accurately and robustly by searching for the best match between a template T-wave and measured T-waves. The authors studied 5 min multichannel ECG recordings (35 channels) measured in 20 healthy subjects. A QT variability of 2.24 +/- 0.79 ms was obtained (1.15 +/- 0.30 ms, if linear detrend was used), which is significantly lower than that reported in several other studies. To explore this discrepancy, the sensitivity of the template matching algorithm to periodic and random noise on the ECG was estimated by a simulation study. The results showed that the repolarisation variability depended on selection of the appropriate lead, the signal-to-noise ratio and the effectiveness of baseline correction. Lead II of a standard 12-lead ECG is a reasonable choice for QT variability analysis; however, precordial leads V3-V6 could be better with regard to the amplitude of the T-wave. Poor signal-to-noise ratios can lead to unrealistic values for repolarisation variability.
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Affiliation(s)
- V Avbelj
- Jozef Stefan Institute, Ljubljana, Slovenia.
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Abstract
The right lateral body position has been proposed as an effective vagal enhancer. However, the possibility of breathing affecting heart rate power spectra in different body positions has not been assessed. The level of vagal modulation in various body positions in normal subjects was estimated by calculating heart rate power spectra. The results suggest that the levels of vagal modulation do not necessarily reflect a change due to assuming different body position, but might be the consequence of changed breathing patterns. Before adopting the right lateral body position as vagal enhancing, the contribution of varying breathing pattern should be eliminated.
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Affiliation(s)
- Viktor Avbelj
- Department of Communications and Computer Networks, Jozef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia.
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Abstract
Non-uniform recovery of excitability may be essential in triggering malignant ventricular tachycardia after cardiac surgery. Thirty-five channels ECG was recorded for 6 min in 27 patients before and after heart surgery and in 20 control subjects. Off-line analysis was performed. RR interval duration, RR SD, QT SD and power spectra of RR variability were computed from 256 s stable RR and QT interval series. When compared to controls, patients had decreased RR SD and increased QT SD before surgery (p<0.002 and p<0.0005, respectively); RR SD further decreased and QT SD increased after the surgery (p<0.0001 and p<0.0002, respectively). Increase of QT variability and decrease of RR variability after cardiac surgery may reflect disrupted electrophysiological stability of the myocardium and thus electrophysiological substrate for triggering malignant arrhythmia.
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Affiliation(s)
- S Frljak
- Department of Cardiovascular Surgery, University Medical Center, Zaloska, 7, Ljubljana 1000, Slovenia
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Abstract
Heart rate variability (HRV) and its assessment using power spectral analysis revealed a possibility to quantify the characteristics of autonomic nervous system, related cardiovascular status and sympathovagal interaction. This study was designed to assess vagal tone in supine and right recumbent position in normal healthy subjects as many maneuvers that potentially increase vagal tone have been sought both in normal subjects and in patients with heart disease. Seven subjects, four male and three female, aged 20-27 years were enrolled in the study. To evaluate the time-dependent stability of short term ECG recordings, every subject participated in six ECG recording sessions (three successive morning and three successive afternoon measurements). Heart rate power spectra were obtained by off-line Fast Fourier Transform analysis. The frequency domain measures, namely very low frequency power (VLF), low frequency power (LF), high frequency power (HF) and total power were determined, and their normalized correlates used in the comparison between supine and right recumbent position. Normalized high frequency (nHF) indicated cardiac vagal activity, normalized low frequency power indexed sympathetic modulated activity, low frequency power/high frequency power ratio (LF/HF) represented sympathovagal balance. The results showed remarkable variation among successive day measurements as well as among study subjects. However, several types of response to adopting right recumbent position could be identified. In the first, in right recumbent position the values of nHF, indicator of vagal activity did not differ appreciably from the values measured in supine position. Secondly, there was a tendency towards higher nHF values and lower LF/HF power ratio in supine position. We were not able to notice any appreciable difference among morning and afternoon short-term measurements. Finally, our results do not suggest higher vagal modulation when lying in right recumbent position.
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Affiliation(s)
- J M Kalisnik
- Department of Cardiovascular Surgery, University Medical Centre, Ljubljana, Slovenia
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Samarin S, Hren R, Trobec R, Avbelj V, Gersak B. Spatial resolution of epicardial pace mapping using body surface potentials. Pflugers Arch 2001; 440:R123-5. [PMID: 11005638] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Abstract
Body surface potential maps (BSPMs) recorded during pace mapping provide an important non-invasive means for identifying local cardiac events; recent clinical studies demonstrated that endocardial pacing sites can be resolved within less than 10 mm. We sought to determine whether similar spatial resolution could be achieved during epicardial pacing. Four patients who were undergoing either heart valve replacement (one), aortocoronary bypass graft (one), or both (two) were studied. In each patient, a pair of epicardial electrodes was placed intraoperatively at the middle aspect of the right ventricular free wall. The distance between the neighbouring electrodes was 10 mm. Five days after the surgery, ECGs were acquired from 35 leads during pacing from each epicardial electrode. We determined the distributions of QRS integrals (the net area under the ECG signal) and compared integrals corresponding to pacing from each of the adjacent electrodes using statistical indices. Student's t-test was applied to these indices and in all the patients revealed that differences in distributions of QRS integral maps were statistically significant (p < 0.01). Results of our study indicate that the non-invasive acquisition of body surface ECGs could resolve epicardial breakthrough sites within 10 mm, which may be useful in facilitating therapeutic ablations in patients with ventricular tachycardias.
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Affiliation(s)
- S Samarin
- Department of Cardiovascular Surgery, Medical Center Ljubljana, Slovenia.
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Abstract
The paper describes and analyses a method for locating metal implants based on the interaction of a conductive object with a weak alternating magnetic field. Theoretical values for the boundary of detectability and the boundary of localability are introduced to show some technical characteristics, the diagnostic feasibility and limitations of the method. Clinical experiences are described in order to compare the theoretical expectations with practical results. Several advantages of the proposed diagnostic method in terms of inexpensive instrumentation, ease of operation and sensitivity are discussed.
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Affiliation(s)
- R Trobec
- Joźef Stefan Institute, Ljubljana, Slovenia
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