The HICS Physiology blog

  Dr. S. Arun Kumaar MD, DrNB Consultant Gastro and Renal Critical Care Services  Apollo Hospital, Greams Road Chennai                                         CONDUCTING SYSTEM OF THE HEART The conducting system of the heart consists of sinoartrial (SA) node, internodal pathways, atrioventicular (AV) node, His bundle, bundle branches and purkinje fibers.   Cardiac action potentials (Fig 1) There are two types of action potential (AP) in the heart. Slow/brief action potential that is created in the SA and AV nodes, and fast/long AP that occurs in the atrial and ventricular myocytes and the specialized conducting fibers Long action potential: This has five phases Phase 0: Due to sudden and rapid opening of voltage dependant sodium channels. Sodium enters the cells and cause depolarisation. Initially activated group of sodium channels serve...

  Dr Priyanka  MD, DM Continental Hospitals, Hyderabad                                VENTRICULAR FILLING PRESSURES  AND BIOMARKERS   Cardiac cycle of the heart has 2 basic phases the systole (contraction) and  the diastole (relaxation/filling) phases. LV filling pressure indicates the pressure in the ventricles during diastole.   SIGNIFICANCE AND TERMS The elevated LVFP( left ventricular filling pressures) can lead to diastolic heart failure or heart failure with preserved ejection fraction. In general, in adults LVFP above 15 mm Hg considered as elevated 1.      LVEDP – LV end diastolic pressure 2.      LAP – left atrial pressure These terms are used to estimate LV filling pressures based on the mode of measurement   UNDERSTANDING LV FILLING PRESSURE IN CARDIAC CYCLE The changes in the volume and pressure in the left ventricle are b...