Cardiovascular Physiology Flashcards
What are the four stages of the valsalva maneouvre?
- Increase in intrathoracic pressure
- Reduced venous return, with stimulation of baroreceptor reflex to produce tachycardia and vasoconstriction
- Rapid reduction in intrathoracic pressure causes pooling of blood in pulmonary vasculature
- Overshoot in blood pressure before levels normalise
How can you manage cyanotic episodes in patients with tetralogy of fallot prior to corrective surgery?
- Oxygen to reduce pulmonary vascular resistance
- Increase systemic vascular resistance using knee-to chest position or squatting
- Opioids and anxiolytics can reduce tachypnoea but may also reduce systemic vascular resistance
- Treat the cause
What are the physiology changes seen during a cyanotic episode in a tetralogy of fallot patient?
- Acute increase in pulmonary vascular resistance
- Leads to increased right to left shunt
- This can also be triggered by an acute decrease in systemic vascular resistance
- Leads to hypoxia, hypercapnoea and acidosis
- This leads to tachypnoea and more negative intrathoracic pressure
- This causes more venous return, which flows via the right to left shunt- This establishes a vicious cycle
What are the triggers of a ‘tet spell’ or cyanotic episode in tetralogy of fallot?
- Tachycardia
- Hypotension
- Crying
- Defaecation
What conditions are associated with tetralogy of Fallot?
- DiGeorge Syndrome
- Down syndrome
- Cleft lip or palate
- Hypospadias
- 22q11 chromosome deletion syndrome
What are the cardinal features of Tetralogy of Fallot?
- Right ventricular outflow obstruction or pulmonary stenosis
- Overriding aorta
- Ventricular septal defect
- Right ventricular hypertrophy
What are the signs on examination of congenital heart disease?
- Cyanosis on exertion e.g. crying
- Tachypnoea and sweating while feeding
- Unexplained persistent tachycardia
- Hepatomegaly
- Peripheral oedema
- Radio-femoral pulse delay
- Murmur (not innocent)
What are the causes of collapse in the neonatal period?
- Congenital heart disease
- Sepsis
- Hypoglycaemia
- Trauma
- Metabolic disorder
- Endocrine disorder
What are the NICE recommendations for chronic heart failure?
First line:
ACE inhibitor
Beta blocker
Second line:
Aldosterone inhibitor
Third line:
Cardiac resynchronisation therapy or digoxin
What are the causes of a fourth heart sound?
Increased atrial activity during diastole, before the first heart sound
It can occur in any left ventricular disease
What is the difference between a thrusting and a tapping apex beat, in terms of cause?
Hypertension causes a thrusting apex beat, while mitral stenosis causes a tapping apex beat
What are the causes of a pathalogical third heart sound?
Mitral regurgitation
Tricuspid regurgitation
Constrictive pericarditis
Dilated left ventricle
Myocardial infarction
How is hypertensive retinopathy graded?
1 - arterial narrowing
2 - arteriovenous nipping
3 - haemorrhages and exudates
4 - all of the above with papilloedema
What are the causes of a prolonged QT interval?
Hypocalcaemia
Myocarditis
Ischaemic heart disease
Hypothermia
Antiarrhythmic drugs
What are the causes of a shortened QT interval?
Hypercalcaemia
Digoxin
Inotropes
Catecholamines
What are the ECG signs of hypothermia?
J waves and a prolonged QT interval
What are the ECG features of Wolff-Parkinson-White syndrome?
Short PR interval
Delta wave (slurred upstroke on QRS)
Wide QRS (type A and type B)
Type A = positive QRS in V1
Type B = negative QRS in V1
This means they can mimic MI
What effect does adenosine have on coronary arteries?
Potent coronary artery dilator
It can cause coronary steal in susceptible patients
What are the ECG criteria for diagnosis of left ventricular hypertrophy?
Sokolov-Lyon criteria:
- Sum of S wave in V1 or V2 + R wave in V5 or V6
- More than 35mm is LVH
Limb leads criteria
- R wave in lead 1 + S wave in lead III
- More than 25mm is LVH
- R wave in AVL >11mm
- R wave in AVF >20mm
- S wave in AVR >14mm
Precordial leads criteria
- R wave in V4, V5 or V6 greater than 26mm
- R wave in V5 or V6 + S wave in V1 > 35mm
- Largest R wave + largest S wave in precordial leads >45mm
There may also be associated ST changes
