Knowledge-based and data-driven models in arrhythmia fuzzy classification.

OBJECTIVES: Fuzzy rules automatically derived from a set of training examples quite often produce better classification results than fuzzy rules translated from medical knowledge. This study aims to investigate the difference in domain representation between a knowledge-based and a data-driven fuzzy system applied to an electrocardiography classification problem. METHODS: For a three-class electrocardiographic arrhythmia classification task a set of fifteen fuzzy rules is derived from medical expertise on the basis of twelve electrocardiographic measures. A second set of fuzzy rules is automatically constructed on thirty-nine MIT-BIH database's records. The performances of the two classifiers on thirteen different records are comparable and up to a certain extent complementary. The two fuzzy models are then analyzed, by using the concept of information gain to estimate the impact of each ECG measure on each fuzzy decision process. RESULTS: Both systems rely on the beat prematurity degree and the QRS complex width and neglect the P wave existence and the ST segment features. The PR interval is not well characterized across the fuzzy medical rules while it plays an important role in the data-driven fuzzy system. The T wave area shows a higher information gain in the knowledge based decision process, and is not very much exploited by the data-driven system. CONCLUSIONS: The main difference between a human designed and a data driven ECG arrhythmia classifier is found about the PR interval and the T wave.

Primary coronary angioplasty in acute myocardial infarction: is it possible to prevent postinfarction cardiac rupture?

BACKGROUND: Cardiac rupture is a leading cause of death among patients hospitalized for acute myocardial infarction (AMI). The aim of our retrospective study was to evaluate the impact of primary coronary angioplasty (PTCA) on this not common but usually fatal complication. METHODS: Since January 1998 PTCA has been the routine treatment for AMI patients in our Institution monitored during the first 12 hours from symptom onset. The AMI patients hospitalized between January 1998 and December 1999 (Group A) were retrospectively compared to those observed between January 1996 and December 1997 (Group B, historical control group), mainly treated with systemic thrombolysis. Patients hospitalized after 12 hours of symptom onset were excluded from the study. Data were analyzed on an intention-to-treat design. RESULTS: Group A consisted of 204 patients (148 males, 56 females, mean age 67 +/- 11 years), 165 (81%) of whom underwent coronary angiography. Group B consisted of 185 patients (123 males, 62 females, mean age 71 +/- 12 years), 78 (42%) of whom were treated with thrombolysis and 33 (18%) with PTCA. The groups did not differ as regards the time delay before hospital entry, Killip class at admission and site of AMI. Fourteen patients (6.8 %) of Group A and 20 (10.8%) of Group B died in the Cardiology Division. No deaths due to cardiac rupture were observed among the 165 Group A patients, nor among the 33 Group B patients treated with PTCA. Cardiac rupture was the cause of death for 1 out of 14 (7%) patients in Group A, and for 8 out of 20 (40%) patients in Group B (p < 0.02 Group A vs Group B). Nine Group A patients and 11 Group B patients died because of cardiogenic shock. CONCLUSION: A lower cardiac rupture incidence was observed among Group A patients in comparison to those of Group B. Thus our data, although not randomized, suggest the ability of primary PTCA in preventing post-AMI cardiac rupture.

A characterization of HRV's nonlinear hidden dynamics by means of Markov models.

A study of the 24-h heart rate variability's (HRV) hidden dynamic is performed hour by hour, in order to investigate the evolution of the nonlinear structure of the underlying nervous system. A hierarchy of null hypotheses of nonlinear Markov models with increasing order n is tested against the hidden dynamic of the HRV time series. The minimum accepted Markov order supplies information about the nonlinearity of the HRV's hidden dynamic and consequently of the underlying nervous system. The Markov model with minimum order is detected for each hour of the RR time series extracted from seven 24-h electrocardiogram records of patients in different pathophysiological conditions, some including ventricular tachycardia episodes. Heart rate, pNN30, and LF/HF index plots are reported to serve as a reference for the description of the patient's cardiovascular frame during each examined hour. The minimum Markov order shows to be a promising index for quantifying the average nonlinearity of the autonomic nervous system's activity.

Dynamics extraction in multivariate biomedical time series.

A nonlinear analysis of the underlying dynamics of a biomedical time series is proposed by means of a multi-dimensional testing of nonlinear Markovian hypotheses in the observed time series. The observed dynamics of the original N-dimensional biomedical time series is tested against a hierarchy of null hypotheses corresponding to N-dimensional nonlinear Markov processes of increasing order, whose conditional probability densities are estimated using neural networks. For each of the N time series, a measure based on higher order cumulants quantifies the independence between the past of the N-dimensional time series, and its value r steps ahead. This cumulant-based measure is used as a discriminating statistic for testing the null hypotheses. Experiments performed on artificial and real world examples, including autoregressive models, noisy chaos, and nonchaotic nonlinear processes, show the effectiveness of the proposed approach in modeling multivariate systems, predicting multidimensional time series, and characterizing the structure of biological systems. Electroencephalogram (EEG) time series and heart rate variability trends are tested as biomedical signal examples.

Signal-averaged ECG abnormalities in haemodialysis patients. Role of dialysis.

BACKGROUND: Late potentials (LP) on the signal-averaged electrocardiogram (SAECG) are predictive of malignant ventricular arrhythmias and sudden cardiac death in patients with ischaemic and non-ischaemic cardiomyopathy. Cardiac dysfunction, both regional and global, as well as supraventricular and ventricular arrhythmias are reported in a high percentage of patients with end-stage renal failure (ESRF). The aim of the study was to assess the prevalence of LP and the effects of haemodialysis on the SAECG of ESRF patients. METHODS: SAECG was recorded immediately before and within 30 min after the end of dialysis in 48 patients in sinus rhythm, free of conduction disturbances on ECG and of signs of congestive heart failure. Serum electrolytes were sampled together with the SAECG recordings. An echo-Doppler exam was performed within 2 weeks of the study. SAECGs were adequate for analysis in 45/48 patients. LP were present when at least two of the following criteria were fulfilled: QRS duration < or = 115 ms, LAS40 < or = 38 ms, RMS40 > or = 38 microV at 40 Hz high pass bidirectional filter, and noise <0.7 microV. RESULTS: LP were detected in 12/45 patients (25%) on the SAECG before dialysis; of these 12 patients, seven had a history of a previous myocardial infarction and two had documented coronary artery disease (CAD). A significant greater wall motion score index--calculated on a 16 segment model--was reported in patients with LP (1.20+/-0.20 vs 1.01+/-0.03, P<0.01), while left ventricular mass was comparable in the two groups of patients. At the end of dialysis, a significant prolongation of fQRS duration was found both at 25 and 40 Hz filters (from 98+/-11 to 106+/-16 ms and from 97+/-12 s to 102+/-13 ms, respectively, P<0.001). A significant inverse relationship was seen between the percentage of dialysis-induced serum potassium reduction and fQRS changes at 40 Hz (r=-0.68, P<0.001). CONCLUSIONS: LP were detected in a significant proportion of dialysis patients, probably related to underlying CAD with left ventricular dysfunction. Prolongation of fQRS after dialysis could be explained by the acute reduction in serum potassium levels.

Chlamydia pneumoniae antibody response in patients with acute myocardial infarction and their follow-up.

STUDY POPULATIONS: This study concerned the possible relations between seroreactivity to Chlamydia pneumoniae and myocardial infarction. A group of 29 patients with acute myocardial infarction (AMI), 74 members of a healthy control group, and a subgroup of 24 members of a healthy control group matched for age, sex, and coronary risk factors (HCM) were included in the study. In addition, we evaluated the AMI group in a 1-year patients' follow-up study. We used two different tests to detect anti-C. pneumoniae antibodies: recombinant enzyme immunoassay antilipopolysaccharide antibodies and a reference microimmunofluorescence test. RESULTS: High titers of C. pneumoniae microimmunofluorescence antibodies were found in 89.65% of the AMI group and in 25% of the HCM group (p = 0.0000065). Immunoglobulin A-microimmunofluorescence was 51.72% in the AMI group and 20.83% in the HCM group (p = 0.0042). Immunoglobulin G and immunoglobulin A antilipopolysoccharide titers were 65.51% and 62.60% in the AMI group and 20.83% in the HCM group, respectively (p = 0.006). High concentrations of interleukin-6 were found in 86.20% of our AMI group (p value = 54.38 pg/ml) when compared with the control group. A good correlation between interleukin-6 levels and immunoglobulin A-lipopolysaccharide titers (r = 0.658) was found. CONCLUSION: The presence of a high prevalence rate and high titers of immunoglobulin G and immunoglobulin A-specific anti-C. pneumoniae antibodies in AMI at admission demonstrated the presence of a specific anti-C. pneumoniae immunization in the AMI population.

[Anti-Chlamydia pneumoniae antibodies and production of interleukin 6 in acute myocardial infarct]. / Anticorpi anti Chlamydia pneumoniae e produzione di interleuchina 6 nell'infarto miocardico acuto.

UNLABELLED: Chlamydia pneumoniae (C.p.) has been correlated with acute myocardial infarction (AMI). High levels of anti-C.p. antibodies and circulating immune complexes containing C.p. lypopolyaaccharide (LPS) antigens have been demonstrated in AMI. LPS antigen and especially Chlamydial LPS is one of the best antigen and it is also a very good Interleukin inductor. Moreover, interleukin 6 (IL-6) has been observed in AMI patients. The aim of our study was to assess the possible relationships between anti-C.p. immune response and IL-6 production in AMI patients. We studied 17 consecutive patients with myocardial infarction (12 males and 5 females; mean age 62; range 46-72). Blood samples were obtained immediately after hospital admission. There were 17 control subjects (HCM) (mean age 62; range 45-72) who were matched for the main coronary risk factors (gender, age, diabetes, hypertension, hypercolesterolemia, smoking, family history of ischemic heart disease). In addition, we evaluated the AMI patients in a one-year follow-up study (FU). RESULTS: High levels of C.p. IgG MIF were found in 82.3% of our AMI patients and in 29.4% of HCM subjects (p = 0.0000065). IgA-MIF were 70.5% in AMI patients and 29.4% in HCM (p = 0.0042). High levels of C.p. IgG and IgA anti-LPS were found, with a very high prevalence rate of 76.4% and 64.7% in AMI patients, and both rates were 47.0% (p = 0.158; p = 0.489) in HCM. Very high levels of IL-6 were found (m = 54.38 pg/ml) in 100% of the AMI patients (normal values in our population: 0-10.86 pg/ml) and only detectable levels in 5.8% of HCM. A good linear correlation was demonstrated between IL-6 and IgA levels in the first sample (r = 0.655). The high levels of anti-C.p. IgG, IgA and IL-6, with a good correlation between IL-6 and IgA levels, may confirm the presence of an active infection and probably of a reinfection.

Italian experience with automated external defibrillators (AED).

In order to achieve widespread use of automated external defibrillators (AEDs) in Italy, we evaluated several models of AEDs in different clinical and artificial settings. We enrolled 268 consecutive patients with various rhythms and arrhythmias. Among these, 129 patients were referred to two different hospitals and 139 were enrolled by the pre-hospital care providers. AED was applied in 209 patients without symptoms of cardiac arrest and in 59 patients with cardiac arrest. The AEDs exhibited a 100% specificity (no false positives in 220 patients with non-shockable rhythm). Sensitivity was 92.3% (4 false negatives and 48 true positives in patients with VT/FV). This study confirms the absolute clinical safety and the high level of diagnostic reliability offered by the AEDs that were tested.

Human heart rate variability and sleep stages.

With the aim of better understanding the dynamic changes in sympatho-vagal tone occurring during the night, human heart rate variability (HRV) during the various sleep stages was evaluated by means of autoregressive spectral analysis. Each recording consisted of an electroencephalogram, an electrooculogram, and electromyogram, and electrocardiogram, and a spirometry trace. All of the data were sampled and stored in digital form. Sleep was analysed visually, but HRV was analysed off-line by means of original software using Burg's algorithm to calculate the LF/HF ratio (LF: 0.04-0.12 Hz; HF: 0.15-0.35 Hz) for each sleep stage. Seven healthy subjects (four males; mean age 35 years) were enrolled in the study. Our findings show a progressive and significant reduction in the LF/HF ratio through sleep stages S1-S4, as a result of an increase in the HF component; this indicates the prevalence of parasympathetic activity during slow-wave sleep. During wakefulness, S1 and REM, the LF/HF values were similar and close to 1.

[Reflex syncope as a preliminary symptom of a rhinopharyngeal lymphoma. A case report]. / Sincope riflessa come sintomo d'esordio di un tumore del rinofaringe. Descrizione di un caso clinico.

The authors report a 57 year old patient affected by rhinopharyngeal NH lymphoma that appeared as a parapharyngeal space lesions-syncope syndrome. The activation of a cardioinhybitory reflex by the stimulation of the glossopharyngeal nerve seems to be the pathogenetic basis for his syndrome.

[Infections due to central catheterizations in a cardiac intensive care unit: an evaluation of 6 months of continuous surveillance. The nursing personnel of a cardiac intensive care unit]. / Infezioni da cateterismi centrali in UTIC: valutazione di sei mesi di sorveglianza continua. Personale infermieristico UTIC.

BACKGROUND: Infections in intensive care unit are nowadays well documented. As no recent papers about catheter related infections in cardiological intensive care units were found, we decided to approach them during a period of six months with a surveillance study including a clinical, nursing and microbiological protocol. METHODS: The microbiological protocol the semiquantitative Maki cultural evaluation of the tips, the interior of the hubs and the skin around the catheter insertion point. In addition, all the samples were additionally cultured in liquid media. A total of 432 biological samples were analysed, from 125 patients entered into our cardiological intensive care unit: 144 from catheter tips, 144 from the hubs and 144 from the skin around the catheter insertion. RESULTS: Three hundred and eighty-four biological samples (88.9%) were completely negative. Thirteen tips resulted positive (27.1% of the 48 total positive biological samples): 92.3% (12/13) of the positive catheters were infected from internal origin, hub and skin resulting culture negative. Of the 144 catheter tips 12 were colonized (C.F.U. < 15) while only 2 resulted infected (C.F.U. > or = 15). Only one patient was infected with an exogenous infection presenting tip, hub and skin positivity. The overall positivity was of 214 microorganisms mainly represented (93.5%) by gram positives; 87% of them were coagulase-negative staphylococci (C.N.S.). In addition, the tip detection of a Candida guillermondii strain in a pacemaker patient is a relevant finding. CONCLUSIONS: The very low number of cutaneous contaminations (1.3%) and patient's infections (0.69%) showed the good sensibilisation of the medical and nursing teams in the infection control and surveillance.

[Changes in pacemakers and the wearers of pacemakers as a result of the use of different electromagnetic energy sources]. / Alterazioni nei pacemaker e nei portatori dei pacemaker in conseguenza dell'uso di varie sorgenti di energia elettromagnetica.

Over the past decade there have been considerable advances in cardiac electrostimulation technologies. However, there are still reports of electromagnetic interference with pacemakers and pacemaker patients. We have studied the effects of various electromagnetic sources (short-wave diathermy, electrosurgical knives, electrotherapy and radiofrequencies) on both humans and animals. The results of the studies were completely negative and, therefore, we are convinced that today's pacemakers are much more reliable and hence less subject to interference from external electromagnetic sources. We performed the following tests: (a) Short-wave diathermy: various electrode positions in pigs and 8 patients with pacemakers. (b) Electrosurgical knives: several tests on pigs with unipolar electrosurgical knife; 6 tests on humans during automatic defibrillator implantation using two-pole electrosurgical knives; 23 pacemaker patients underwent abdominal surgery (3 inguinal hernias, 12 gastric resections; 6 cholecystotomies, 2 aortic aneurysms-with two-pole electrosurgical knives). (c) Electrotherapy (TENS): on pigs. (d) Radiofrequency (RF) for transcatheter ablation-several tests on pigs.

[Risk stratification in patients with a first myocardial infarct based on simple clinico-instrumental variables]. / Stratificazione del rischio in pazienti con primo infarto miocardico in base ad alcune semplici variabili clinico-strumentali.

UNLABELLED: It is an acknowledged fact that the prognosis for patients with a first myocardial infarction depends mainly on the degree of residual left ventricle function. We wanted to evaluate the importance that certain simple clinical and instrumental variables can have in stratifying post-infarction cardiovascular risk with particular emphasis on chronic obstructive lung disease (COLD). We selected 97 out of the 512 patients treated in the coronary intensive care unit (CICU) from February 1, 1988 to October 31, 1990 according to the following criteria: First myocardial infarction; no cardiogenic shock; no serious concomitant diseases with considered negative prognosis within 6 months. The following variables were considered for all the patients: age; sex; positive family history for ischemic heart disease; history of diabetes mellitus; arterial hypertension; previous cerebrovascular incident; history of obstructive arteriopathy of the lower limbs, of angor and COLD. The following tests were performed on all the patients: echocardiogram prior to discharge form the CICU; angiocardioscintigraphy with Tc-99 between the 20th and 30th day following the acute event; bicycle ergometer stress test on the 30th day. END POINTS: general mortality; cardiac mortality; non-fatal reinfarction; residual angina at 3 months. All the patients were treated with aspirin (325 mg/die) and/or heparin (12,500 units subcutaneously). All 97 patients were monitored for a mean follow-up time of 19.8 months. General mortality was 2.08% (for reinfarction) 24 (24.7%) non-fatal cardiac events.(ABSTRACT TRUNCATED AT 250 WORDS)

[Disorders of atrioventricular conduction in Ebstein's anomaly in an adult. A report of 5 cases]. / Disturbi della conduzione atrioventricolare nell'Ebstein dell'adulto. Presentazione di 5 casi.

From the literature we find that the most frequent electrical alterations in Ebstein's anomaly are: the abnormal right atriogram; ventricular pre-excitation; supraventricular tachycardia; right bundle branch block and lengthening of the PR tract. These alterations are also present in cases of Ebstein's anomaly diagnosed in adults. The study of the activation of the right ventricle, which offers a variety of forms of development, is a source of particular interest. We report five cases which have come to our attention, in which greater disturbances of the atrioventricular block were present. This aspect has not yet been clearly reported in the literature.

Circadian variations of heart rate and premature beats in healthy subjects and in patients with previous myocardial infarction.

Chronobiological analysis of the circadian variations of heart rate, ventricular and atrial ectopies, was carried out on 11 patients with previous myocardial infarction matched with 11 controls. Individual circadian rhythms in heart rate were seen in all the control subjects but only in 6 patients with previous myocardial infarction. The behaviour of the individual circadian rhythms of premature beats was not significantly different between the two groups. A significant group rhythm in ectopies was not demonstrated, nevertheless a trend to higher frequency of arrhythmias during the activity span was detected. These results do not allow to postulate a circadian pattern of arrhythmias common to all the subjects examined. Therefore, the individual circadian behaviour of premature atrial and ventricular beats should be recognized for monitoring antiarrhythmic therapy. A significant group rhythm in heart rate was demonstrated for the two populations studied and linear discriminant analysis showed that the amplitude of this rhythm was significantly lower in patients than in controls. Possibly, myocardial infarction may affect the sinus node function producing a "flattened" range of heart rates during the 24 hours.

[Circadian and ultradian rhythms of the heart rate in the neonate]. / Ritmi circadiani ed ultradiani della frequenza cardiaca nel neonato.

Few papers deal with the chronobiologic characteristics of heart rate in neonates. A better knowledge of this topic could be useful under both clinical and therapeutical point of view. We studied the circadian and ultradian rhythms of heart rate in 10 healthy neonates (5 males and 5 females). Six of them (60%) show a well defined circadian rhythm of heart rate such as adult subjects even if with an obviously higher mesor and with acrophases dispersed throughout the 24 hours. We also demonstrated one or more ultradian rhythms of heart rate for each neonate. The most frequent have a period between 4 hours and 6 minutes and 4 hours and 36 minutes. These rhythms are out of phase with the world outside which is the best evidence that they are not imposed by some undetected external factors.

Heart rate and premature beats: a chronobiologic study.

Sixteen subjects, mean age 59 +/- 18, 11 normal and 5 with coronary artery disease, all having premature ventricular and/or atrial beats in the standard resting electrocardiogram (ECG), were studied to analyse the chronobiologic parameters of these arrhythmias. Single cosinor analysis of the data obtained by 96-hour ECG performed according to the Holter system, demonstrated: A) significant circadian rhythm in heart rate for all the subjects, with acrophases occurring between 12.56 and 17.36; B) significant circadian rhythms of premature ventricular beats for the majority of the subjects, with acrophases distributed along the 24 hours; C) significant circadian rhythms in premature atrial beats for 8 subjects, with acrophases occurring between 04.24 and 18.12; D) a spectrum of significant ultradian rhythms in heart rate with various periodicities, both in normal and in coronary patients; E) significant ultradian rhythms in premature ventricular beats for 8 subjects with periods ranging from 5h 15' to 17h. Population mean cosinor analysis demonstrated: A) significant circadian group rhythm in heart rate for all the 16 subjects and for the group of 11 normal subjects; B) no significant circadian group rhythm for premature ventricular and atrial beats. These findings suggest that the study of the individual chronobiologic pattern of premature beats may help to optimize antiarrhythmic therapy.