Aortic Stenosis, Atrial Fibrillation, Cerebral Infarction Flashcards
What is aortic stenosis?
One of the most common and serious valve disease problems.
The narrowing of the aortic valve opening –> restricting blood flow from left ventricle to the aorta
What is normal function of aortic valve?
Opens to allow blood to exit the left ventricle, closes to prevent blood from passing back from aorta to left ventricle
What is it called when blood passes back to ventricle from aorta?
Regurgitation
What is the cause from birth of (congenital) aortic stenosis?
The valve may have 2 cusps (bicuspid) instead of the usual 3 cusps (tricuspid)
What is the cause gradually over the years of aortic stenosis?
Valve becomes calcified (deposition of calcium causing stiffening) and narrowed (stenosed)
What is effect on left ventricle of aortic stenosis?
Left ventricle has to generate more force (pressure) to eject blood through the narrowed aortic valve and becomes more muscular (hypertrophied)
What is the thickening of muscle fibres called when the body has been stressed?
Hypertrophy
Who is mainly affected by aortic stenosis?
Males over the age of 65. Can cause no symptoms for many years
What are the symptoms of aortic stenosis?
SAD
S - Syncope (light-headedness, with exercise)
A - Angina type chest pain (worse with exercise)
D - Dyspnoea (breathlessness, with exercise)
What are the clinical signs of aortic stenosis relating to heart murmur?
Harsh and loud ‘ejection systolic’ heart murmur heard loudest in the top right side of the chest (aortic area)
Aortic area –> right side, between 2nd and 3rd rib (2nd intercostal space)
What are systolic heart murmurs?
Ejection murmurs are murmurs that may arise from narrowing of the semilunar valves or outflow tracts
Systolic murmur begins during or after first heart sound and ends before or during second heart sound
What is effect on pulse pressure during aortic stenosis?
Reduced pulse pressure (difference between systolic blood pressure and diastolic blood pressure)
Normally 120/70 mmHg (50 mmHg difference) changed to 110/90 mmHg (20 mmHg difference)
What is clinical signs during aortic stenosis relating to apex beat?
Forceful apex beat –> felt on left side of chest in mid-clavicular line, 5th intercostal space
Due to hypertrophied LV
What would the abnormal test results of ECG and echocardiogram be during aortic stenosis?
ECG –> evidence of more muscular left ventricle (QRS is increased in size)
Echocardiogram –> shows a narrowed aortic valve and a more muscular left ventricle
What is an echocardiogram?
Ultrasound scan of the heart
When is medical/surgical intervention required for aortic stenosis?
- If pressure difference between left ventricle and aorta remains below 60 mmHg then the patient is kept under observation
- If the left ventricle starts to dilate then surgery is considered
- Aortic valve can be replaced by open chest surgery or using a percutaneous (through skin and via femoral artery) approach
How are surgical valves made?
Either made of metal and plastic (prosthetic) or are pig valves (tissue valves)
What do patients with metallic artificial aortic (and other) valves require after treatment?
Life-long anticoagulant treatment with warfarin
What do patients with tissue valves require after treatment?
Do not require warfarin
What is atrial fibrillation?
Quivering or irregular heartbeat (arrhythmia) characterised by rapid and irregular beating of atrial chambers of heart
The heart is taken out of normal sinus rhythm due to production of electrical impulses originating from the atrial myocytes
What anatomical structures does atrial fibrillation involve?
- Left and right atria of the heart
- Pulmonary veins where meet the left atrium
What is physiologically affected in AF?
- Pacemaker activity of heart (SA node)
- Conduction of electrical depolarisation through atrium
- Stimulation of electrical activity in ventricles
In AF –> atria contract randomly and abnormal electrical impulses start firing in the atria and override heart’s natural pacemaker
What structural abnormalities are present in AF?
- Dilated atria
- Fibrosis (scarring) of atrial muscle
What physiological abnormalities are present in AF?
Pacemaker of heart (SA node) overwhelmed by disorganised atrial electrical discharge (often originating at pulmonary vein insertion)
What prior events could to lead to AF?
- Hypertension (high blood pressure)
- 1ary heart diseases (including coronary artery disease)
- Lung diseases (pneumonia, lung cancer, pulmonary embolism)
- Excessive alcohol consumption
- Hyperthyroidism (overactive thyroid gland)
- Heart failure
What is the difference between atrial flutter and atrial fibrillation?
Similar but rhythm in flutter is more organised and less chaotic