Things you should know about Cardiac markers for MI: 1) Myoglobin first comes and first goes (rises first, disappears first). (2) LDH is called “lazy enzyme” because it comes late, and goes late (rises after 24 hours and remain till 14 days). (3) Trop-I has the greatest sensitivity and specificity. (4) The investigation of choice within first hour of MI is “CKMB”(5)”CKMB” is useful for confirmation of reinfarction as this enzyme disappears after 72 hours of MI. So, if a patient comes after 72 hours of initial infarction, and you are suspecting a reinfarction, go for “CKMB”. Myoglobin disappears after 24 to 48 hours.CKMB disappears after 72 hours.Trop I disappears after 7 – 10 days.LDH disappears after 14 days. SOME IMP POINTS OF CVS Stimulation of Right vagus slows the heart by inhibiting the SA node an stimulation of Left vagus nerve mainly slows the AV conduction.Stimulation of Right stallete ganglion accelerates the heart and stimulation of Left stellate ganglion shortens the AV nodal conduction. SA node discharge increases with increase in temperature justifying tachycardia in fever.ATRIAL FLUTTER: atrial rate is 200-350/min. mostly there is counterclockwise circus movement in RIGHT ATRIUM. This produces SAW TOOTH appearance. It is almost always associated with 2:1 or greater AV block. AV node cannot conduct more than 230 impulses per minute.ATRIAL FIBRILLATION: atrial rate more than 300-500/min and in irregular way. Ventricles also beat irregularly at 80 to 160/min. Its exact cause is still in debate but most commonly it occurs due to multiple concurrently circulating reentrant excitation waves in BOTH atria. Some cases may also occurs due to discharge of one or more ectopic foci. Many of these foci appear in pulmonary veins s much as 4 cm from the heart. Atrial muscle fibrs extend along pulmonary vein and site of origin of these foci. MURMURS: aortic/ pulmonary valves… stenosis=systolic murmur, insufficiency=diastolic Mitral or tricuspid valves… stenosis =diastolic murmur, insufficiency systolic. Sleep don’t cause any change on Cardiac output.Athletes have greater end systolic volume and stroke volumes and lower heart rates.BP pressure falls upto 20mmHg in sleep… in HTN this fall is reduced or absent,So normal persons are called DIPPERS and hypertensive persons are called NONDIPPERS.Noradrenergic fibers end on the vessels in all parts of the body which are mainly vasoconstrictor in function.. resistance vessels in skeletal muscles are innervated by VASODILATOR fibers which although trevel thru the sympethetics but are CHOLINERGIC.there is some evidence that vessels in heart, lungs , kidneys, and ureters also receive cholinergic innervations. The afferent nerve fibers from the carotid sinus and carotid body form a distinct branch of glossopharyngeal nerve called CAROTID SINUS NERVE. The carotid sinus nerve and vagal fibers from the aortc arch commonly called the BUFFER NERVES.During shock the vasoconstriction is most marked in SKIN. Source
