Daniel Felipe Ortega

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The aim of the present study was to evaluate the mechanism of cerebrovascular autoregulation in patients with neurocardiogenic syncope using bilateral transcranial Doppler (TCD) monitoring during head upright tilt table testing (HUT). Two hundred and six patients were prospectively studied. One hundred and fifty-nine subjects (77%) had a prior history of(More)
Recognition of the P wave is important for the correct characterization of atrial and ventricular arrhythmias. When the P wave is difficult to identify on standard electrocardiography (SECG), either esophageal electrocardiography (EECG) or intracardiac electrocardiography (IC-ECG), central venous catheter may be used. The feasibility of these methods has(More)
Ejection fraction (EF), the ratio between stroke volume (SV) and end-diastolic volume (EDV), is a valuable contractility indicator. Unlike SV, the Frank-Starling effect is automatically compensated in the calculation of EF. It was the aim of this study to evaluate the physiological behavior of impedance derived measurements of relative right ventricular(More)
DDD and AAI pacemakers are considered physiological, since they preserve atrioventricular (AV) synchrony. Artificial pacing, however, is performed largely from right heart chambers, causing aberrant depolarization pathways. Pacing at the right atrial appendage (RAP) is known to delay left atrial contraction due to interatrial conduction time (IACT), and(More)
Runaway is an uncommon pacemaker dysfunction, characterized by fast and erratic spikes at non-physiological rates. This infrequent but potentially lethal failure mode may be related to low battery voltage. Four single chamber pacemaker patients were analyzed (Medtronic Minix ST 8330, Minneapolis, MN, had been implanted in two patients and two CPI Triumph VR(More)
A method for improving the muscle incoordination associated with cerebral palsy was empirically tested. Relaxation exercises, involving the successive tensing and relaxing of the major muscle groups of the body, were performed by four adults with spastic quadraplegia. All four subjects were sheltered workshop employees. Their IQs ranged from normal to(More)
Coronary sinus mapping is commonly used to evaluate left atrial activation. Herein, we propose to use it to assess which right ventricular pacing modality produces the shortest left ventricular activation times (R-LVtime) and the narrowest QRS widths. Three study groups were defined: 54 controls without intraventricular conduction disturbances; 15 patients(More)