L3 cardio Flashcards

Question

CO flowchat

Answer 1

HR x stroke volume = cardiac output – So... The faster the heart rate the better the cardiac output?... Up to a point Too fast a heart rate: – Less time for ventricular filling – So less stretch on the ventricle wall... so less force of contraction – Also less time for coronary artery filling during diastole

Answer 2

– Average blood pressure in aorta – BP = CO x PR – CO in the volume of blood per min – PR is total resistance against which blood must be pumped

Answer 3

– Hypertension (high blood pressure) is defined as the consistent elevation in systemic arterial pressure. – It is estimated that 3.7 million Australians aged over 25 years have high blood pressure or are on medication to treat high blood pressure. – Diagnosis is based on serial blood pressure (BP) measurements at different times. – A diagnosis of hypertension will be made when systolic blood pressure is consistently equal to or greater than 140 mmHg or diastolic pressure is 90 mmHg or greater. – Genetic and lifestyle risk factors contribute to the development of hypertension.

Answer 4

Defined as cardiac impairment with inability to fill or eject blood volume Causes: – ischaemic heart disease (over 50% of new cases) – hypertension (about two-thirds of cases) – idiopathic dilated cardiomyopathy (around 5–10% of cases) –Left ventricular failure most common (congestive heart failure) –Right sided heart failure may also occur (often due to lung pathology eg COPD)

Answer 5

Prevalence: – 2% of total population – 3-5% \> 65 years old – 10%\>75yearsold – Hypertension and coronary heart disease most common cause. – Left ventricular failure most common (congestive heart failure). – Defined as cardiac impairment with inability to fill or eject blood volume. – Mortality 5 years from diagnosis.

Answer 6

– Systole is when the heart squeezes, diastole is when the heart relaxes and fills.

Answer 7

Cardiac Cycle – Cardiac cycle refers to all events associated with blood flow through the heart – Systole – contraction of heart muscle – Diastole – relaxation of heart muscle

Answer 8

– Normal PR Interval – 0.12 - 0.20 secs – ( 3 – 5 small boxes) – Normal QRS – less than 0.12 sec – Less than 3 small boxes

Answer 9

Sinus node activity is correlated with age – lengthening of time sino-atrial node takes to recover – lengthening of time sino-atrial node takes conduct. – progressive lengthening of sinus cycle length Progressive decrease of parasympathetic activity with increasing age. – parasympathetic activity predominates in younger people – sympathetic and parasympathetic tone becomes more equal in older people.

Answer 10

– Inflammatory cardiac disease – Cardiomyopathy – Sclerodegenerative processes (replacement of normal organ-specific tissue with connective tissue) – Coronary artery disease – poor blood supply to SA node

Answer 11

– Coronary artery disease – Rheumatic heart disease – Inflammatory diseases – Connective tissue disorders – Calcification

Answer 12

Preload is the volume of blood that fills the ventricles during diastole –Influenced by ‘atrial kick’ (is there a P wave?) –Influenced by AV synchrony (Are P waves followed closely by QRS waves?) The greater the venous return, the more the myocardial fibres will stretch (Frank Starlings Law) –Loss of atrial kick and poor AV synchrony can mean poor cardiac output !

Answer 13

rhythm too slow- inadequate O2 too fast, inadequete filling serious ventricular irritability

Answer 14

– Some medications e.g. digoxin, Beta Blockers – Natural degeneration of the SA or AV nodes – Surgery or disease of the aortic or mitral valves (very close to AV node) – Threatened blood supply to the SA or AV nodes

Answer 15

– Re-entry circuits – Myocardial irritability - poor blood supply - poor oxygen supply - potassium and magnesium imbalances – Acute infections - Especially new atrial fibrillation from pneumonia, UTI etc – Myocardial scarring