Information-Theoretic Analysis of Cardio-Respiratory Interactions in Heart Failure Patients: Effects of Arrhythmias and Cardiac Resynchronization Therapy.

The properties of cardio-respiratory coupling (CRC) are affected by various pathological conditions related to the cardiovascular and/or respiratory systems. In heart failure, one of the most common cardiac pathological conditions, the degree of CRC changes primarily depend on the type of heart-rhythm alterations. In this work, we investigated CRC in heart-failure patients, applying measures from information theory, i.e., Granger Causality (GC), Transfer Entropy (TE) and Cross Entropy (CE), to quantify the directed coupling and causality between cardiac (RR interval) and respiratory (Resp) time series. Patients were divided into three groups depending on their heart rhythm (sinus rhythm and presence of low/high number of ventricular extrasystoles) and were studied also after cardiac resynchronization therapy (CRT), distinguishing responders and non-responders to the therapy. The information-theoretic analysis of bidirectional cardio-respiratory interactions in HF patients revealed the strong effect of nonlinear components in the RR (high number of ventricular extrasystoles) and in the Resp time series (respiratory sinus arrhythmia) as well as in their causal interactions. We showed that GC as a linear model measure is not sensitive to both nonlinear components and only model free measures as TE and CE may quantify them. CRT responders mainly exhibit unchanged asymmetry in the TE values, with statistically significant dominance of the information flow from Resp to RR over the opposite flow from RR to Resp, before and after CRT. In non-responders this asymmetry was statistically significant only after CRT. Our results indicate that the success of CRT is related to corresponding information transfer between the cardiac and respiratory signal quantified at baseline measurements, which could contribute to a better selection of patients for this type of therapy.

Effects of Cardiac Resynchronization Therapy on Cardio-Respiratory Coupling.

In this study, the effect of cardiac resynchronization therapy (CRT) on the relationship between the cardiovascular and respiratory systems in heart failure subjects was examined for the first time. We hypothesized that alterations in cardio-respiratory interactions, after CRT implantation, quantified by signal complexity, could be a marker of a favorable CRT response. Sample entropy and scaling exponents were calculated from synchronously recorded cardiac and respiratory signals 20 min in duration, collected in 47 heart failure patients at rest, before and 9 months after CRT implantation. Further, cross-sample entropy between these signals was calculated. After CRT, all patients had lower heart rate and CRT responders had reduced breathing frequency. Results revealed that higher cardiac rhythm complexity in CRT non-responders was associated with weak correlations of cardiac rhythm at baseline measurement over long scales and over short scales at follow-up recording. Unlike CRT responders, in non-responders, a significant difference in respiratory rhythm complexity between measurements could be consequence of divergent changes in correlation properties of the respiratory signal over short and long scales. Asynchrony between cardiac and respiratory rhythm increased significantly in CRT non-responders during follow-up. Quantification of complexity and synchrony between cardiac and respiratory signals shows significant associations between CRT success and stability of cardio-respiratory coupling.

Diagnostic value of implantable loop recorders in patients with unexplained syncope or palpitations.

BACKGROUND: The implantable loop recorder (ILR) is a small cardiac rhythm-monitoring device. Our aim was to determine ILR diagnostic value in patients with unexplained syncope, presyncope, or palpitations suggesting cardiac arrhythmias. METHODS: This has been a retrospective, observational, single-center study. We included 181 patients in whom ILR was implanted at the Clinical Center of Serbia between January 2006 and July 2019. An event was marked as diagnostic if it led to a diagnosis and ILR was considered diagnostic if it verified or excluded an arrhythmia as the cause of syncope or palpitations. RESULTS: The mean age was 51.8 ± 17.8 years and 94 (51.9%) were male. The mean follow-up period was 20.2 ± 15.8 months. ILR was diagnostic in 98 patients (54.1%). There was no significant difference in diagnostic value of ILR in regard to the baseline patients' characteristics. The mean time to occurrence of the diagnostic event was 11.1 ± 9.6 months. The time to occurrence of a diagnostic event did not differ significantly between patients who underwent basic as compared to extended diagnostics before ILR implantation. CONCLUSIONS: ILR was able to achieve an etiological diagnosis in 54.1% of patients with unexplained syncope, presyncope, or palpitations suggesting cardiac arrhythmias. In a subgroup of patients with recurrent palpitations, ILR was significantly less diagnostic than in patients with syncope or presyncope. ILR should be implanted beforehand in syncope evaluation process.

Multiscale Entropy Analysis: Application to Cardio-Respiratory Coupling.

It is known that in pathological conditions, physiological systems develop changes in the multiscale properties of physiological signals. However, in real life, little is known about how changes in the function of one of the two coupled physiological systems induce changes in function of the other one, especially on their multiscale behavior. Hence, in this work we aimed to examine the complexity of cardio-respiratory coupled systems control using multiscale entropy (MSE) analysis of cardiac intervals MSE (RR), respiratory time series MSE (Resp), and synchrony of these rhythms by cross multiscale entropy (CMSE) analysis, in the heart failure (HF) patients and healthy subjects. We analyzed 20 min of synchronously recorded RR intervals and respiratory signal during relaxation in the supine position in 42 heart failure patients and 14 control healthy subjects. Heart failure group was divided into three subgroups, according to the RR interval time series characteristics (atrial fibrillation (HFAF), sinus rhythm (HFSin), and sinus rhythm with ventricular extrasystoles (HFVES)). Compared with healthy control subjects, alterations in respiratory signal properties were observed in patients from the HFSin and HFVES groups. Further, mean MSE curves of RR intervals and respiratory signal were not statistically different only in the HFSin group (p = 0.43). The level of synchrony between these time series was significantly higher in HFSin and HFVES patients than in control subjects and HFAF patients (p < 0.01). In conclusion, depending on the specific pathologies, primary alterations in the regularity of cardiac rhythm resulted in changes in the regularity of the respiratory rhythm, as well as in the level of their asynchrony.

Differentiation of Heart Failure Patients by the Ratio of the Scaling Exponents of Cardiac Interbeat Intervals.

Heart failure (HF) is one of the most frequent heart diseases. It is usually characterized with structural and functional cardiac abnormalities followed by dysfunction of autonomic cardiac control. Current methods of heartbeat interval analysis are not capable to differentiate HF patients and some new differentiation of HF patients could be useful in the determination of the direction of their treatment. In this study, we examined potential of the ratio of the short-term and long-term scaling exponents (α 1 and α 2) to separate HF patients with similar level of reduced cardiac autonomic nervous system control and with no significant difference in age, left ventricular ejection fraction (LVEF) and NYHA class. Thirty-five healthy control subjects and 46 HF patients underwent 20 min of continuous supine resting ECG recording. The interbeat interval time series were analyzed using standardized power spectrum analysis, detrended fluctuation analysis method and standard Poincaré plot (PP) analysis with measures of asymmetry of the PP. Compared with healthy control group, in HF patients linear measures of autonomic cardiac control were statistically significantly reduced (p < 0.05), heart rate asymmetry was preserved (C up > C down, p < 0.01), and long-term scaling exponent α 2 was significantly higher. Cluster analysis of the ratio of short- and long-term scaling exponents showed capability of this parameter to separate four clusters of HF patients. Clusters were determined by interplay of presence of short-term and long-term correlations in interbeat intervals. Complementary measure, commonly accepted ratio of the PP descriptors, SD2/SD1, showed tendency toward statistical significance to separate HF patients in obtained clusters. Also, heart rate asymmetry was preserved only in two clusters. Finally, a multiple regression analysis showed that the ratio α 1/α 2 could be used as an integrated measure of cardiac dynamic with complex physiological background which, besides spectral components as measures of autonomic cardiac control, also involves breathing frequency and mechanical cardiac parameter, left ventricular ejection fraction.

Heart failure in cardiomyopathies: a position paper from the Heart Failure Association of the European Society of Cardiology.

Cardiomyopathies are a heterogeneous group of heart muscle diseases and an important cause of heart failure (HF). Current knowledge on incidence, pathophysiology and natural history of HF in cardiomyopathies is limited, and distinct features of their therapeutic responses have not been systematically addressed. Therefore, this position paper focuses on epidemiology, pathophysiology, natural history and latest developments in treatment of HF in patients with dilated (DCM), hypertrophic (HCM) and restrictive (RCM) cardiomyopathies. In DCM, HF with reduced ejection fraction (HFrEF) has high incidence and prevalence and represents the most frequent cause of death, despite improvements in treatment. In addition, advanced HF in DCM is one of the leading indications for heart transplantation. In HCM, HF with preserved ejection (HFpEF) affects most patients with obstructive, and ∼10% of patients with non-obstructive HCM. A timely treatment is important, since development of advanced HF, although rare in HCM, portends a poor prognosis. In RCM, HFpEF is common, while HFrEF occurs later and more frequently in amyloidosis or iron overload/haemochromatosis. Irrespective of RCM aetiology, HF is a harbinger of a poor outcome. Recent advances in our understanding of the mechanisms underlying the development of HF in cardiomyopathies have significant implications for therapeutic decision-making. In addition, new aetiology-specific treatment options (e.g. enzyme replacement therapy, transthyretin stabilizers, immunoadsorption, immunotherapy, etc.) have shown a potential to improve outcomes. Still, causative therapies of many cardiomyopathies are lacking, highlighting the need for the development of effective strategies to prevent and treat HF in cardiomyopathies.

Bidirectional Cardio-Respiratory Interactions in Heart Failure.

We investigated cardio-respiratory coupling in patients with heart failure by quantification of bidirectional interactions between cardiac (RR intervals) and respiratory signals with complementary measures of time series analysis. Heart failure patients were divided into three groups of twenty, age and gender matched, subjects: with sinus rhythm (HF-Sin), with sinus rhythm and ventricular extrasystoles (HF-VES), and with permanent atrial fibrillation (HF-AF). We included patients with indication for implantation of implantable cardioverter defibrillator or cardiac resynchronization therapy device. ECG and respiratory signals were simultaneously acquired during 20 min in supine position at spontaneous breathing frequency in 20 healthy control subjects and in patients before device implantation. We used coherence, Granger causality and cross-sample entropy analysis as complementary measures of bidirectional interactions between RR intervals and respiratory rhythm. In heart failure patients with arrhythmias (HF-VES and HF-AF) there is no coherence between signals (p < 0.01), while in HF-Sin it is reduced (p < 0.05), compared with control subjects. In all heart failure groups causality between signals is diminished, but with significantly stronger causality of RR signal in respiratory signal in HF-VES. Cross-sample entropy analysis revealed the strongest synchrony between respiratory and RR signal in HF-VES group. Beside respiratory sinus arrhythmia there is another type of cardio-respiratory interaction based on the synchrony between cardiac and respiratory rhythm. Both of them are altered in heart failure patients. Respiratory sinus arrhythmia is reduced in HF-Sin patients and vanished in heart failure patients with arrhythmias. Contrary, in HF-Sin and HF-VES groups, synchrony increased, probably as consequence of some dominant neural compensatory mechanisms. The coupling of cardiac and respiratory rhythm in heart failure patients varies depending on the presence of atrial/ventricular arrhythmias and it could be revealed by complementary methods of time series analysis.

Left atrial phasic function and heart rate variability in patients with systemic sclerosis: A new part of the old puzzle.

OBJECTIVE: We aimed to research left atrial (LA) phasic function and heart rate variability (HRV), as well as their relationship, in subjects with uncomplicated systemic sclerosis (SSc). METHODS: The investigation involved 44 SSc patients and 33 age-matched healthy controls. All participants underwent clinical examination, serological tests, 24-hours Holter monitoring, and echocardiographic examination including strain analysis. RESULTS: Maximum, minimum, and pre-A LA volumes and volume indices were higher in the SSc patients than in the controls. The total emptying fraction, the parameter of the LA reservoir function, as well as passive LA emptying fraction, which represents the LA conduit function, were significantly lower in the SSc patients compared to the controls. Active LA emptying fraction, the parameter of the LA booster pump function, was significantly higher in the SSc participants. There was no difference in LA reservoir function between the diffuse and the limited SSc form. LA conduit function was significantly decreased, whereas LA booster pump function was compensatory increased in the diffuse SSc form compared to the limited SSc form. Similar results were obtained by LA strain analysis. HRV indices were significantly decreased in the SSc patients. Modified Rodnan skin score, the parameter of skin involvement in SSc, and HRV indices correlated well with LA phasic function in SSc. CONCLUSION: Left atrial (LA) phasic function, assessed by both volumetric and strain method, as well as cardiac autonomic nervous function is significantly deteriorated in SSc patients. Skin score and HRV indices correlate with LA phasic function parameters.

Uncoupling of cardiac and respiratory rhythm in atrial fibrillation.

Rearranged origin of heart rhythm in patients with atrial fibrillation (AF) influences the regulation of the heart and consequently the respiratory rhythm, and the bidirectional interaction of these rhythms not documented. Hence, we examined coupling of the RR interval and the respiration (Resp) signal by coherence, Granger causality and the cross-sample entropy method of time series analysis in patients with AF and a healthy control group. In healthy subjects, the influence of respiration on cardiac rhythm was found as increased coherence at the breathing frequency (BF) range, significantly stronger interaction and synchrony from Resp to RR than from RR to Resp. On the contrary, in patients with AF, coherence at BF diminished, there were no causal interactions between signals in both directions, which resulted in equally great asynchrony between them. In AF, the absence of full functionality of the sinoatrial node, as an integrator of neural cardiac control, resulted in diminished vagal modulation of heart periods and consequently impaired bidirectional cardio-respiratory interaction.

Generalized Poincaré Plots-A New Method for Evaluation of Regimes in Cardiac Neural Control in Atrial Fibrillation and Healthy Subjects.

Classical Poincaré plot is a standard way to measure nonlinear regulation of cardiovascular control. In our work we propose a generalized form of Poincaré plot where we track correlation between the duration of j preceding and k next RR intervals. The investigation was done in healthy subjects and patients with atrial fibrillation, by varying j,k ≤ 100. In cases where j = k, in healthy subjects the typical pattern was observed by "paths" that were substituting scatterplots and that were initiated and ended by loops of Poincaré plot points. This was not the case for atrial fibrillation patients where Poincaré plot had a simple scattered form. More, a typical matrix of Pearson's correlation coefficients, r(j,k), showed different positions of local maxima, depending on the subject's health condition. In both groups, local maxima were grouped into four clusters which probably determined specific regulatory mechanisms according to correlations between the duration of symmetric and asymmetric observed RR intervals. We quantified matrices' degrees of asymmetry and found that they were significantly different: distributed around zero in healthy, while being negative in atrial fibrillation. Also, Pearson's coefficients were higher in healthy than in atrial fibrillation or in signals with reshuffled intervals. Our hypothesis is that by this novel method we can observe heart rate regimes typical for baseline conditions and "defense reaction" in healthy subjects. These data indicate that neural control mechanisms of heart rate are operating in healthy subjects in contrast with atrial fibrillation, identifying it as the state of risk for stress-dependent pathologies. Regulatory regimes of heart rate can be further quantified and explored by the proposed novel method.

The interaction between blood pressure variability, obesity, and left ventricular mechanics: findings from the hypertensive population.

OBJECTIVE: The aim of this study was to determine the relationship between blood pressure (BP) variability and left ventricular (LV) mechanical function in untreated normal-weight, overweight, and obese hypertensive patients. METHODS: This cross-sectional study included 144 untreated hypertensive study participants who underwent 24-h ambulatory BP monitoring and complete two (2DE) and three-dimensional echocardiography (3DE). All the patients were divided into three groups according to their BMI: normal-weight patients (BMI < 25 kg/m), overweight patients (25 ≤ BMI < 30 kg/m), and obese patients (BMI ≥ 30 kg/m). RESULTS: Daytime, night-time, and 24-h BP variability progressively increased from normal-weight, throughout overweight, to obese hypertensive study participants. 2DE and 3DE LV longitudinal, circumferential and radial strains, as well as 3DE area strain, were significantly lower in obese hypertensive patients than in normal-weight and overweight study participants. 3DE LV volumes indexed for BSA did not differ significantly among the three observed groups. Night-time and 24 h BP variability indices, more than daytime BP variability parameters, were associated with 2DE and 3DE longitudinal and circumferential strains independent of BMI, LV mass index, and average 24-h SBP and DBP values. CONCLUSION: BP variability and LV deformation are significantly affected by obesity in untreated hypertensive patients. BP variability is associated with 2DE and 3DE LV mechanics independently of main clinical and echocardiographic characteristics.

Is pacemaker therapy the right key to patients with vasovagal syncope?

Introduction: Vasovagal syncope is the most common type of reflex syncope. Efficacy of cardiac pacing in this indication has not been the subject of many studies and pacemaker therapy in patients with vasovagal syncope is still controversial. Objective: This study aimed to assess the efficacy and safety of pacing therapy in treatment of patients with vasovagal syncope, to determine contribution of new therapeutic models in increasing its success, and to identify risk factors associated with a higher rate of symptoms after pacemaker implantation. Methods: A retrospective study included 30 patients with pacemaker implanted due to vasovagal syncope in the Pacemaker Center, Clinical Center of Serbia, between November 2003 and June 2014. Head-up tilt test was performed to diagnose vasovagal syncope. Patients with cardioinhibitory and mixed type of disease were enrolled in the study. Results: Mean age was 48.1 ± 11.1 years and 18 (60%) patients were men. Mean follow-up period was 5.9 ± 3.0 years. Primarily, implantable loop recorder was implanted in 10 (33.3%) patients. Twenty (66.7%) patients presented cardioinhibitory and 10 (33.3%) mixed type of vasovagal syncope. After pacemaker implantation, 11 (36.7%) patients had syncope. In multiple logistic regression analysis we showed that syncope is statistically more likely to occur after pacemaker implantation in patients with mixed type of vasovagal syncope (p = 0.018). There were two (6.7%) perioperative surgical complications. Conclusion: Pacemaker therapy is a safe treatment for patients with vasovagal syncope, whose efficacy can be improved by strict selection of patients. We showed that symptoms occur statistically more often in patients with mixed type of disease after pacemaker implantation.

Treatment strategies for carotid artery aneurysms.

BACKGROUND: The aim of this paper was to present single centre experience in the treatment of extra cranial carotid artery aneurysms (ECCA) and to analyze results discussing different treatment modalities. METHODS: The study analyzed 60 patients with 62 ECCA treated surgically at the Clinic for vascular and endovascular surgery, Serbian Clinical Center (Belgrade) in the period between 1985 and 2013. Treatment strategy was individually selected and demographic, morphologic, intraoperative and postoperative data were collected. RESULTS: Thirty-day operative mortality was 3.3% and completely stroke related. Besides two fatal strokes one additional was registered making total number of 3 (4.8%) postoperative strokes. Only one (1.6%) early graft thrombosis has been found. The 30-day-patency rate was 98.4%. During the same period seven local complications were found: three (4.8%) hemorrhage and four (6.4%) cranial nerves injuries. In all cases of hemorrhage successful re-intervention was performed without any consequences. Cranial nerves injuries included transient contusions of hypoglossal (2) and superior laryngeal nerve (2). CONCLUSIONS: The etiology, location, and morphology of an ECCA are determining selection of appropriate therapy. Large or tortuous aneurysms, as well as aneurysms involving common carotid or proximal internal carotid artery, are also absolutely indicated to open surgical therapy. Aneurysms which involve the distal internal carotid artery and false anastomotic aneurysms are best managed with endovascular techniques. The ligature is indicated for the treatment of external carotid aneurysms, mycotic aneurysms with local infection and in ruptured ECCA with uncontrolled bleeding.

The Relationship of Myocardial Collagen Metabolism and Reverse Remodeling after Cardiac Resynchronization Therapy.

BACKGROUND: In the majority of patients with a wide QRS complex and heart failure resistant to optimal medical therapy, cardiac resynchronization therapy (CRT) leads to reverse ventricular remodeling and possibly to changes in cardiac collagen synthesis and degradation. We investigated the relationship of biomarkers of myocardial collagen metabolism and volumetric response to CRT. METHODS: We prospectively studied 46 heart failure patients (mean age 61±9 years, 87% male) who underwent CRT implantation. Plasma concentrations of amino-terminal propeptide type I (PINP), a marker of collagen synthesis, and carboxy-terminal collagen telopeptide (CITP), a marker of collagen degradation, were measured before and 6 months after CRT. Response to CRT was defined as 15% or greater reduction in left ventricular end-systolic volume at 6-month follow-up. RESULTS: Baseline PINP levels showed a negative correlation with both left ventricular end-diastolic volume (r=-0.51; p=0.032), and end-systolic diameter (r=-0.47; p=0.049). After 6 months of device implantation, 28 patients (61%) responded to CRT. No significant differences in the baseline levels of PINP and CITP between responders and nonresponders were observed (p>0.05 for both). During follow-up, responders demonstrated a significant increase in serum PINP level from 31.37±18.40 to 39.2±19.19 µg/L (p=0.049), whereas in non-responders serum PINP levels did not significantly change (from 28.12±21.55 to 34.47± 18.64 µg/L; p=0.125). There were no significant changes in CITP levels in both responders and non-responders (p>0.05). CONCLUSIONS: Left ventricular reverse remodeling induced by CRT is associated with an increased collagen synthesis in the first 6 months of CRT implantation.

Association between left ventricular mechanics and heart rate variability in untreated hypertensive patients.

The authors sought to investigate left ventricular (LV) mechanics and heart rate variability (HRV), and their relationship, in untreated hypertensive patients. A total of 63 untreated hypertensive patients and 45 healthy patients were included. All patients underwent 24-hour Holter monitoring and echocardiographic examination (two- and three-dimensional). All parameters of time and frequency domain of HRV were decreased in the hypertensive patients. Two-dimensional LV longitudinal and circumferential deformation was significantly reduced in hypertensive patients. Three-dimensional LV strain in all three directions as well as area strain were reduced in the hypertensive group. In two different models of multivariate regression, two-dimensional LV longitudinal and circumferential strain, as well as three-dimensional LV area strain, remained associated with HRV parameters independently of LV structural and functional parameters. This study showed that LV mechanics and HRV were significantly impaired in untreated hypertensive patients. Two- and three-dimensional echocardiographic LV deformation were independently associated with HRV parameters in the whole study population.

[Approach to the Treatment of Atrial Fibrillation in Patients with Cardiovascular Risk Profile: Multicentric International Study].

INTRODUCTION: Atrial fibrillation (AF), the most common arrhythmia that requires treatment, does not come out of the focus of researchers. Monitoring its prevalence and effects of therapy is a good guideline approach to the growing population of patients in which this arrhythmia occurs. OBJECTIVE: The aim of the study was to evaluate the efficacy of treatment of AF and cardiovascular profiles in the observed population. METHODS: In this observational, cross-sectional, multicenter, international study, 584 patients in 30 centers in Serbia and Slovenia, older than 18 years and with AF or in sinus rhythm with a history of AF, were included. The assessment of the efficacy of treatment of AF was performed by analyzing the frequency of adequate therapeutic effect of medication in rhythm or frequency control in patients with AF. RESULTS: The results confirmed that the highest incidence of AF duration is more than seven days, and is accompanied by symptoms. Inadequate frequency regulation was registered at 8.9% of patients. Hypertension was registered in two-thirds of all patients, while other cardiovascular risk factors were registered in about one-third of patients. An echocardiographic finding in the group of patients with AF confirms generally adequate left ventricular function with a slightly enlarged left atrium (4.6±0.8 cm). Increasing age and time from the first episode of AF decreases the probability of maintaining sinus rhythm, while symptomatic AF had a positive impact on the presence of sinus rhythm. Propafenone, sotalol and amiodarone showed a statistically significant connection with a positive therapeutic response, while 3-blockers had a negative impact on the probability of establishing and maintaining sinus rhythm. CONCLUSION: Characteristics of therapeutic approaches, risks, comorbidity of patient populations in Slovenia and Serbia correspond to the fullest extent with the recommendations for good clinical practice, which further stresses the need for extensive measures in these regions.

[Brain natriuretic peptide as a predictor of heart failure in patients with permanent pacemaker].

INTRODUCTION: Brain natriuretic peptide (BNP) has a role in control of cardiovascular and renal functions. OBJECTIVE: The objective was to assess the predictive value of BNP levels for development of heart failure in patients with permanent pacemakers. METHOD: In patients with implanted DDD pacemakers, BNP levels were measured at rest and after exercise testing, on DDD and VVI modes. There were 42 patients (25 males; 59.5%), without symptoms or signs of coronary disease or heart failure, and with normal echocardiograms. According to BNP levels, the patients were divided into three groups: with BNP levels lower than 80 pg/ml, BNP ranging from 81-150 pg/ml, and BNP levels over 151 pg/ml. RESULTS: In the first group (27 patients), BNP levels were significantly higher on VVI compared to DDD mode, both at rest and after exercise (p < 0.01), with all BNP levels within normal range. In the second group (5 pts), BNP levels at rest were also significantly higher on VVI than on DDD mode, p < 0.05. After exercise, these values were also higher on VVI compared to DDD mode, but without statistical significance. The third group (10 pts) as a whole had higher BNP values on VVI compared to DDD mode, with no statistical significance. In patients from this group who later developed heart failure, BNP levels were found to be significantly lower on DDD as opposed to VVI mode at rest, p < 0.05, and even higher significance was found after exercise, p < 0.01. After 6-year follow-up, 2 out of 5 patients from the second group developed dilated cardiomyopathy, and 8/10 patients in the third group experienced heart failure with LV EF 34.1 +/- 10%, LV EDD 6.1 +/- 0.42 cm, LV ESD 4.8 +/- 0.45 cm. Five of these patients died within the follow-up period. CONCLUSION: The increased BNP levels can be valuable for early screening of patients with higher risk of heart failure. In patients with increased BNP at the time of pacemaker implantation, DDD pacing is a modality of choice.

Fracture of the subcutaneous patch electrode in a patient with an implanted cardioverter-defibrillator.

There are more than 20 years of experience with implantation of defibrillator devices in humans and the procedure is an important therapeutic option for patients at high risk of life-threatening ventricular arrhythmias. The incidence of new defibrillator implantation has gradually increased, being used even in children, (1) although pediatric use is associated with several complications, especially with epicardial systems,(2) including fracture of the subcutaneous patch,(3-5) mainly because of growth.(3) We present a case of subcutaneous patch electrode fracture in the left axillary pectoral region of a patient who needed the patch for effective defibrillation, and we discuss the methods of treatment.

[Implantable "loop recorder"--a new diagnostic tool for syncope of unknown cause].

INTRODUCTION: The implantable loop recorder (ILR) is a new diagnostic tool in cardiology for establishing the causes of unexplained syncope in patients where standard conventional tests, invasive tests included, have failed. The device is a diagnostic "pacemaker," surgically implanted underneath the skin of the chest, with leads attached to the case of the device, not requiring endovenous lead implantation. Heart rhythm is monitored continuously on the basis of an endless loop, up to a maximum period of 14 months. Recording is carried out either by applying an outside activator whenever symptoms occur, or automatically, according to a pre-set algorithm for bradycardia, tachycardia, and/or asystolic detection. OBJECTIVE: The aim of this study was to present this new diagnostic method as well as our first experiences with its implementation. METHOD: We followed 5 patients (3 male, 2 female, mean age: 46.4 +/- 19) who had ILRs ("Reveal Plus," Medtronic Inc., USA) implanted at our centre, over a period of 14 months (7.6 +/- 5.5), concentrating on their clinical course, symptom occurrence, and electronically monitored heart rhythm at the time of ILR auto activation and/or recordings triggered by outside activation whenever a patient's symptoms were discernible. RESULTS: In three patients, the ILR revealed syncope aetiology by documenting heart rhythm at the time of its occurrence. In one patient, involving a lethal outcome, the ILR was not explanted, so that the rhythm at the time of the fatal syncope, although assumed, remained undocumented. In one, most recently implanted patient, follow-up is still in progress. CONCLUSION: The implantable loop recorder represents an important innovation and a step forward in establishing the causes of recurrent syncope, which cannot be determined by standard invasive and non-invasive testing.

[Resynchronisation therapy in patients with heart failure: our results].

INTRODUCTION: Resynchronisation therapy with biventricular permanent pacing stimulation is one method of treating patients with systolic heart failure, with echocardiograph signs of ventricular asynchrony and a prolonged QRS of longer than 120 milliseconds. This method has been accepted in most medical centres around the world and was instigated in our Pacemaker Centre in December 2001, 3 months after FDA approval for human use. OBJECTIVE: The aim of the study was to present this new procedure and the results obtained from our own group of patients. METHOD: A multi-site, biventricular pacemaker, with a special electrode for left-half heart stimulation was implanted in the coronary sinus of 17 patients who had suffered systolic heart failure (12 male and 5 female, average age 59.9 years). For all of them, the duration of the QRS interval was longer than 120 ms, with left bundle branch morphology, and an ejection fraction below 30%. All the patients were NYHA class II or III. Prior to and after the implantation, a 12-channel ECG and ECHO were carried out, a 6-minute hall walk test was performed, additionally, the total walked distance on a flat surface was measured, the general condition of the patient was evaluated, the number of medications being taken was noted, as was the number of days of hospitalisation. RESULTS: The average time from diagnosis to implantation was 22 months, and the average post-operative follow-up was 14 months. Two of the patients died 10 and 7 months after the implantation, due to a new myocardial infarction and refractory heart failure. In addition, one patient did not show any improvement after the implantation of the multi-site pacemaker (there were three "non-responder" patients). All the other patients felt much better: decreased NYHA class for I - II class, increased left ventricle ejection fraction, reduced use of diuretics, increased 6-minute hall walk distance and general walk distance on a flat surface, and decreased number of days of hospitalisation. CONCLUSION: Resynchronisation heart failure therapy in the majority of patients with systolic left ventricular dysfunction and a prolonged QRS interval considerably improves cardiac function, in addition to reducing symptoms and hospital stays.