Induced effects of transcranial magnetic stimulation on the autonomic nervous system and the cardiac rhythm.

Several standard protocols based on repetitive transcranial magnetic stimulation (rTMS) have been employed for treatment of a variety of neurological disorders. Despite their advantages in patients that are retractable to medication, there is a lack of knowledge about the effects of rTMS on the autonomic nervous system that controls the cardiovascular system. Current understanding suggests that the shape of the so-called QRS complex together with the size of the different segments and intervals between the PQRST deflections of the heart could predict the nature of the different arrhythmias and ailments affecting the heart. This preliminary study involving 10 normal subjects from 20 to 30 years of age demonstrated that rTMS can induce changes in the heart rhythm. The autonomic activity that controls the cardiac rhythm was indeed altered by an rTMS session targeting the motor cortex using intensity below the subject's motor threshold and lasting no more than 5 minutes. The rTMS activation resulted in a reduction of the RR intervals (cardioacceleration) in most cases. Most of these cases also showed significant changes in the Poincare plot descriptor SD2 (long-term variability), the area under the low frequency (LF) power spectrum density curve, and the low frequency to high frequency (LF/HF) ratio. The RR intervals changed significantly in specific instants of time during rTMS activation showing either heart rate acceleration or heart rate deceleration.

Real-time frequency-independent single-Lead and single-beat myocardial infarction detection.

This study proposes a novel real-time frequency-independent myocardial infarction detector for Lead II electrocardiograms. The underlying Deep-LSTM network is trained using the PTB-XL database, the largest to date publicly available electrocardiography dataset, and is tested over the same and the older PTB database. By testing the model over distinct datasets, collected under different conditions and from different patients, a more realistic measure of the performance can be gauged from the deployed system. The detector is trained over 3589 myocardial infarction (MI) patients and 7115 healthy controls (HC) while it is evaluated on 1076 MIs and 1840 HCs. The proposed algorithm, achieved an accuracy of 77.12%, recall/sensitivity of 75.85%, and a specificity of 83.02% over the entire PTB database; 85.07%, 81.54%, 87.31% over the PTB-XL validation set (fold 9), and 84.17%, 78.37%, 87.55% over the PTB-XL test set (fold 10). The model also achieves stable performance metrics over the frequency range of 202 Hz to 2.8 kHz. The processing time is dependent on the sampling frequency, ranging from 130 ms at 202 Hz to 1.8 s at 2.8 kHz. Such outcome is within the time required for real-time processing (less than 300 ms for fast heartbeats), between 202 Hz and 500 Hz making the algorithm practically real-time. Therefore, the proposed MI detector could be readily deployed onto existing wearable and/or portable devices and test instruments; potentially having significant societal and clinical impact in the lives of patients at risk for myocardial infarction.

Efecto del levamisol en la trombosis coronaria experimental / Effect of levamisole on experimental coronary thrombosis

El levamisol es un inhibidor selectivo de la tromboxano-sintetasa, por lo cual nos planteamos evaluar el papel que desempeña como agente trombolítico. Se utilizó un modelo experimental en perro, al que se le producía un trmbo en la coronaria descendente y en la vena femoral, y posteriormente se le suministraba levamisol (20 mg/kg). Se realizó una serie control, sin droga, y se compararon los resultados de ambos grupos de animales. En los animales a los que se les suministró levamisol, el desnivel de ST aparecía con la trombosis e iba disminuyendo paulatinamente, reperfundiendo la coronaria. De este grupo de animales solamente 2 mantuvieron el trombo en la luz del vaso. En el grupo control todos los animales presentaron trombo en las coronarias y en las venas. La frecuencia cardiaca y la presión arterial no presentaron cambios significativos en ninguno de los dos grupos experimentales. Estos resultados sugieren que la droga fue efectiva, aunque no de forma absoluta, igual que la mayorìa de las drogas trombolíticas