Predictive models of syncope causes in an outpatient clinic.

UNLABELLED: The investigation of unexplained syncope remains a challenging clinical problem. In the present study we sought to evaluate the diagnostic value of a standardized work-up focusing on non invasive tests in patients with unexplained syncope referred to a syncope clinic, and whether certain combinations of clinical parameters are characteristic of rhythmic and reflex causes of syncope. METHODS AND RESULTS: 317 consecutive patients underwent a standardized work-up including a 12-lead ECG, physical examination, detailed history with screening for syncope-related symptoms using a structured questionnaire followed by carotid sinus massage (CSM), and head-up tilt test. Invasive testings including an electrophysiological study and implantation of a loop recorder were only performed in those with structural heart disease or traumatic syncope. Our work-up identified an etiology in 81% of the patients. Importantly, three quarters of the causes were established non invasively combining head-up tilt test, CSM and hyperventilation testing. Invasive tests yielded an additional 7% of diagnoses. Logistic analysis identified age and number of significant prodromes as the only predictive factors of rhythmic syncope. The same two factors, in addition to the duration of the ECG P-wave, were also predictive of vasovagal and psychogenic syncope. These factors, optimally combined in predictive models, showed a high negative and a modest positive predictive value. CONCLUSION: A standardized work-up focusing on non invasive tests allows to establish more than three quarters of syncope causes. Predictive models based on simple clinical parameters may help to distinguish between rhythmic and other causes of syncope.

[Sudden cardiac death: epidemiology and modern therapy]. / La mort subite: de l' épidémiologie à la prévention.

Sudden Cardiac Death (SCD) has become an important public health challenge in the Western World. In Switzerland near 10,000 people suffer each year from SCD. The survival from SCD to hospital discharge is discouraging (near 5%). Large majority of events occur unexpectedly in the out-of-hospital environment and are not predicted with great accuracy by risk profiling. Because the majority of SCD occur by the mechanism of ventricular fibrillation, community-based defibrillation strategies have emerged as one approach to SCD problem. Newer strategies of defibrillation designed to respond faster to out-of-hospital cardiac arrest, including public access defibrillation, as well as aggressive primary and secondary prevention of coronary artery disease appears as the best approach for successful management of SCD.

Lateral thermal damage along pulsed laser incisions.

The damage adjacent to incisions created in dorsal mouse skin by overlapping Er3+ and CO2 laser pulses of a duration of 250 microseconds is investigated histologically. It is compared to injuries induced by long-term heating. We demonstrate how the lateral thermal damage near the laser cuts can be explained by heat conduction. We show that it is necessary to introduce as a heat reservoir a layer of tissue that has been liquified during the cutting process. The width of the thermally damaged region depends mainly on the extension of the liquid material that remains in the cut after the laser-tissue interaction.