Heart Lecture 1 PDF

Heart and Muscle Damage Dr Karan Rana Learning Outcomes Principles of using serum enzymes, other proteins and metabolites as diagnostic tools. Methods involved in measuring the above. Apply such principles to the diagnosis of the conditions acute myocardial infarction and heart failure...

Heart and Muscle Damage Dr Karan Rana Learning Outcomes Principles of using serum enzymes, other proteins and metabolites as diagnostic tools. Methods involved in measuring the above. Apply such principles to the diagnosis of the conditions acute myocardial infarction and heart failure Recap  Diagnosis.  Management.  Progression of disease.  Response to treatment.  Recurrence of disease.  Screening – detection in asymptomatic individuals.  Population - newborn screening.  Selected group - obese patients for type II diabetes mellitus.  Individual - familial hypercholesterolaemia. Recap  Tissue specific (i.e. only present within one tissue).  Rapid release in response to damage.  Very low in serum of normal individuals.  Easily measured with clear universal reference values.  If these criteria are difficult to achieve use a battery of tests to make a profile. Assay of Serum Biomarkers  Enzyme activity:  Rate of change in absorbance e.g. aspartate aminotransferase. Aspartate + 2-oxoglutarate glutamate + oxaloacetate Oxaloacetate + NADH + H+ malate + NAD+ Change in absorbance per min aspartate aminotransferase activity ( mol/min/ml) = 6.22 x 1 Extinction coefficient for NADH = 6.22 mM-1 cm-1 Assay of Serum Biomarkers  Amount of protein / enzyme:  Immunological methods e.g. ELISA.  Enzyme-linked immunosorbent assay. Assay of serum biomarkers  Metabolites:  Enzymatic or chemical conversion to a coloured product.  Spectrophotometric measurements.  Beer-Lambert law. Acute Myocardial Infarction  Imbalance between myocardial oxygen supply and demand.  Results in muscle injury / death.  Often caused by coronary thrombosis.  Vessels become blocked because of fissure / rupture of the intimal surface of an atheromatous plaque. Acute myocardial infarction Diagnosis of AMI  Subjects presenting with acute onset chest pain.  May have suspected acute coronary syndrome or may have pain from another organ.  Acute coronary syndrome may be due to AMI or unstable angina with no accompanying tissue damage  Improved by rest or vasodilators such as glyceryl trinitrate. Diagnosis of AMI  Typical abrupt and total loss of coronary blood flow results in ST segment elevated MI (STEMI) with a typical ECG (electrocardiogram).  Partial loss of coronary perfusion can give rise to non-ST segment elevated MI (NSTEMI) with changes in T wave or ST depression or no change at all. R R T Problem: only 75% of T P P patients with AMI show any diagnostic changes in ECG Q Q S Normal S STEMI  Summary Serum proteins have a diagnostic value particularly when quantified using a sensitive method such as ELISA. Myocardial infraction is the reduced supply of oxygen to the heart causing tissue death. Using non-biochemical tests can be useful but you would still need to run biochemical tests in order to come to a diagnosis.