Nico Nico Pijls

Functional Measurement of Coronary Stenosis

Fractional flow reserve (FFR) is considered nowadays as the gold standard for invasive assessment of physiologic stenosis significance and an indispensable tool for decision making in coronary revascularization. Use of FFR in the catheterization laboratory accurately identifies which lesions should be stented and improves the outcome in most elective clinical and angiographic conditions. Recently, FFR has been upgraded to a class IA classification in multivessel percutaneous coronary intervention in the guidelines on coronary revascularization of the European Society of Cardiology. In this state-of-the-art paper, the basic concept of FFR and its application, characteristics, and use in several subsets of patients are discussed from a practical point of view.

A mock circulation model for cardiovascular device evaluation

The aim of this study was to develop an integrated mock circulation system that functions in a physiological manner for testing cardiovascular devices under well-controlled circumstances. In contrast to previously reported mock loops, the model includes a systemic, pulmonary, and coronary circulation, an elaborate heart contraction model, and a realistic heart rate control model. The behavior of the presented system was tested in response to changes in left ventricular contractile states, loading conditions, and heart rate. For validation purposes, generated hemodynamic parameters and responses were compared to literature. The model was implemented in a servo-motor driven mock loop, together with a relatively simple lead-lag controller. The pressure and flow signals measured closely mimicked human pressure under both physiological and pathological conditions. In addition, the systems response to changes in preload, afterload, and heart rate indicate a proper implementation of the incorporated feedback mechanisms (frequency and cardiac function control). Therefore, the presented mock circulation allows for generic in vitro testing of cardiovascular devices under well-controlled circumstances.

Circadian and weekly variation and the influence of environmental variables in acute myocardial infarction

ObjectivesThe aim of our study was to investigate the circadian and weekly variation and assess the influence of environmental variables on the occurrence of acute myocardial infarction (AMI).MethodsOur study population consisted of 2983 consecutive patients admitted with AMI between January 2006 and May 2008. Data were abstracted from hospital records and partially from an electronic database. In patients with a known time of onset of AMI, circadian variation was analysed. In all patients, weekly variation of onset of AMI was analysed. Information on daily mean temperature, sunny hours, rainy hours, maximal humidity and mean atmospheric pressure was obtained from the KNMI database and the influence of these environmental variables on the incidence of AMI was analysed.Results and conclusionIncidence of AMI shows a circadian pattern with an increase in occurrence during daylight. AMI occurs equally on each day of the week and no relation was found between environmental variables and the occurrence of AMI.