A New Wavelet-Based ECG Delineator for the Evaluation of the Ventricular Innervation.

T-wave amplitude (TWA) has been proposed as a marker of the innervation of the myocardium. Until now, TWA has been calculated manually or with poor algorithms, thus making its use not efficient in a clinical environment. We introduce a new wavelet-based algorithm for the delineation QRS complexes and T-waves, and the automatic calculation of TWA. When validated in the MIT/BIH Arrhythmia database, the QRS detector achieved sensitivity and positive predictive value of 99.84% and 99.87%, respectively. The algorithm was validated also on the QT database and it achieved sensitivity of 99.50% for T-peak detection. In addition, the algorithm achieved delineation accuracy that is similar to the differences in delineation between expert cardiologists. We applied the algorithm for the evaluation of the influence in TWA of anticholinergic and antiadrenergic drugs (i.e., atropine and metoprolol) for healthy subjects. We found that the TWA decreased significantly with atropine and that metoprolol caused a significant increase in TWA, thus confirming the clinical hypothesis that the TWA is a marker of the innervation of the myocardium. The results of this paper show that the proposed algorithm can be used as a useful and efficient tool in clinical practice for the automatic calculation of TWA and its interpretation as a non-invasive marker of the autonomic ventricular innervation.

Application of a new robust ECG T-wave delineation algorithm for the evaluation of the autonomic innervation of the myocardium.

T-wave amplitude (TWA) is a well know index of the autonomic innervation of the myocardium. However, until now it has been evaluated only manually or with simple and inefficient algorithms. In this paper, we developed a new robust single-lead electrocardiogram (ECG) T-wave delineation algorithm that is able to detect the T-wave with a wavelet based method and automatically calculate the TWA. We evaluated the algorithm on the QT database, achieving a sensitivity of 99.92% for the T wave peak and 99.38% for the T wave end. In addition, the percentage of records automatically delineated with high precision was higher than previous published works. Finally, the algorithm was applied to study the influence of anticholinergic and antiadrenergic drugs (i.e. atropine and metoprolol) on the TWA. It was observed that atropine significantly decreased the TWA when compared to baseline level, that head-up tilt caused a decrease of TWA and that metoprolol blunted this decrease. Through the development of a robust algorithm, this study opens the way for further research on the T-wave analysis for the assessment of the autonomic innervation of the ventricular myocardium.

Comparative study of T-amplitude features for fitness monitoring using the ePatch® ECG recorder.

This study investigates ECG features, focusing on T-wave amplitude, from a wearable ECG device as a potential method for fitness monitoring in exercise rehabilitation. An automatic T-peak detection algorithm is presented that uses local baseline detection to overcome baseline drift without the need for preprocessing, and offers adequate performance on data recorded in noisy environments. The algorithm is applied to 24 hour data recordings from two subject groups with different physical activity histories. Results indicate that, while mean heart rate (HR) differs most significantly between the groups, T-amplitude features could be useful depending on the disparities in fitness level, and require further investigation on an individual basis.

Spontaneous regression of metastases from malignant melanoma: a case report.

A case of a 61-year-old male with widespread metastatic melanoma is presented 5 years after complete spontaneous cure. Spontaneous regression occurred in cutaneous, pulmonary, hepatic and cerebral metastases. A review of the literature reveals seven cases of regression of cerebral metastases; this report is the first to document complete spontaneous regression of cerebral metastases from malignant melanoma by means of computed tomography scans. Spontaneous regression is defined as the partial or complete disappearance of a malignant tumour in the absence of all treatment or in the presence of therapy, which is considered inadequate to exert a significant influence on neoplastic disease. The incidence of spontaneous regression of metastases from malignant melanoma is approximately one per 400 patients, and possible mechanisms include immunologic, endocrine, inflammatory and tumour nutritional factors. Our patient engaged in alternative therapies and was taking a number of different dietary supplements, none of which can be medically recommended, but the combination of which possibly strengthened the immune system and thereby the host defense against the melanoma metastases.

[Diagnosis and treatment of syncope]. / Udredning og behandling af reflekssynkoper.

Syncope is associated with considerable costs to society as well as to the patient. Syncope may arise on a neurological, cardiac, or neurovascular background. Cardiac and neurological causes are evaluated by standard methods. Neurovascular syncope is diagnosed by tilt table testing and carotid massage. The treatment of neurological or cardiac syncope aims at the underlying cause, whereas the treatment of neurovascular syncope consists of information and instruction in reasonable precautions. In persisting cases, medical treatment or pacemaker implantation may be necessary.

[Investigation in suspected syncope. A study of more than 1,174 consecutively referred patients]. / Udredning ved mistanke om synkope. En opgørelse over 1.174 konsekutivt henviste patienter.

INTRODUCTION: Syncope is a common cause of acute hospitalization and may be associated with poor quality of life. History and physical examination can exclude most frequent cardiac or neurological causes, leaving two main diagnostic groups--postural and reflex syncope. The purpose of the study was to compare two forms of tilt testing and to describe the diagnostic patterns associated with these methods. MATERIALS AND METHODS: The study included 1,174 patients (722 women) aged 11 to 96 years consecutively referred from primary (24.6%) and secondary care units (75.4%). Two groups of equal size were studied by the standard tilt tests with or without nitroglycerine administration. Blood pressure and heart rate were monitored continuously by non-invasive methods. RESULTS: The diagnostic yield was 29% and 64% without and with nitroglycerin, respectively (p < 0.0001). The diagnostic yield was independent of age and sex but reflex syncope occurred more often in women and postural syncope was more common in men (p < 0.0001). Postural syncope dominated in patients over 55 years whereas reflex syncope dominated in younger patients (p < 0.0001). DISCUSSION: The diagnostic yield and the pattern of outcome from tilt testing are highly dependent upon the selected protocol. CONCLUSION: Postural and reflex syncope occur in all age groups, but the former is more frequent in the elderly and the latter more frequent in the young. The use of nitroglycerine significantly increases the diagnostic yield of tilt testing.

Autonomic and electrocardiographic changes in cardioinhibitory syncope.

AIMS: Cardioinhibitory syncope (CS) is a neurally mediated response causing bradycardia or asystole. This study reports on changes in blood pressure, heart rate variability (HRV), and ECG patterns before and after syncope with asystole. METHODS AND RESULTS: Thirty-five patients with CS and a matched control group were submitted to 60 degrees head-up tilt for 20 min with the addition of nitroglycerin. Syncope developed after a tilt-duration of 1.082 (range 50-1.734 s). Asystole lasted for 21.3 s (range 3.4-80.2 s) and was preceded by sinus rhythm in 21, junctional rhythm in 10, and atrioventricular block in four. Asystole was followed by sinus rhythm in four, junctional rhythm in 24, atrioventricular block in four, and atrial fibrillation in three. The two groups did not differ with respect to supine heart rate, HRV or blood pressure. Prior to syncope, patients showed significant increases in total and low-frequency HRV with reductions in high-frequency HRV and a progressive shortening of the PR-interval. CONCLUSION: Syncope was preceded by marked accentuation of sympathetic tone with a sudden shift in heart rate control to vagal dominance. Asystole was accompanied by vagally induced, benign arrhythmia in the majority of the patients.