T9-L2: Cardiovascular Pathology 2 Flashcards
What is congestive heart failure?
CHF specifically refers to the stage in which fluid builds up within the heart and causes it to pump inefficiently. It can occur insidiously or suddenly:
- Due to cumulative effects of chronic workload such as HTN or valve disease
- Acute haemodynamic stress - fluid overload and large myocardial infraction
What is the pathogenesis of left sided heart failure?
The cause is varied e.g. through HTN causing pressure overload, valvular disease causing pressure/volume overload or myocardial infarction which can cause regional dysfunction with volume overload.
This overload leads to increased cardiac work, and increased wall stress. This causes the cells stretch (to enhance contractibility according to Starling’s law). The hypertrophy and/or dilation can cause cardiac dysfunction characterised by heart failure, arrhythmia and neurohumoral stimulation (release of norepinephrine, activation of RAAS etc.).
What is the effect of hypertension on the heart?
Adaptive left-ventricular hypertrophy leads to myocyte striking, thickening of ventricular wall, thereby deceasing the left ventricular chamber.
However chronic, persistent hypertension, leads to maladaptive hypertrophy. The myocytes continue to lengthen. The left ventricular wall gets thinner (dialled) and the left ventricular chamber increases in size.
How does Left sided heart failure present?
Leads to signs and symptoms of low cardiac output leading to hypo perfusion to tissues.
Clinical effects: - Pulmonary congestion and oedema - Heart failure cells - Macrophages with hemosiderin. High pulmonary blood pressure causes RBC to travel through the vascular wall and become ingested by macrophages. The product of this is hemosiderin.
Signs and symptoms:
- Dyspnoea - Orthopnoea - PND - Paroxysmal Nocturnal Dyspnoea - Blood tinged Sputum - Cyanosis - Pulmonary hypertension
How does left sided heart failure effect the kidneys?
- Pre-renal azotaemia - abnormally high levels of nitrogen containing compounds in the blood. This can lead to AKI. This is due to Inadequate perfusion to the kidney, causing an increase in the interglomerular pressure leading to arise in serum creatinine concentration.
- RAAS - When renal blood flow is reduced juxtaglomerular cells produce renin. This leads to increased salt and fluid retention to increase blood pressure. Further volume overload can result in a failing system. We then give RAAS inhibiting drugs in heart failure.
What are the signs and symptoms of right sided heart failure?
- ‘Systemic and portal venous system engorgement”
- Signs of portal hypertension: Splenomegaly, Ascites, Congested liver
- Signs of fluid build up Congestion and oedema
- Pleural/pericardium (systemic venous congestion): Pleural and pericardial effusions, transudates, Oedema of peripheral and dependent parts of the body
What is the most common cause of right sided heart failure?
Cor Pulmonale.
It can also be caused by left heart failure.
Give causes of aortic stenosis.
- Age due to calcification of the valves - tends be seen more in the over 70s
- Can be seen in younger patients if they have a congenitally deformed valve - tends to be in the form of a bicuspid aortic valve
- Rheumatic Fever
What is a major cause of mitral stenosis?
Rheumatic Heart Disease
What is the effect of rheumatic over acutely and chronically on the heart?
Acute:
- Inflammation
- Pancarditis
- Vegetations on chordal tendinae at leaflets junctions (bacteria, fibrin and platelet)
- Histological changes
Chronic:
- Thickened valves
- Commsiural fissure
- Thick, short, chord tendinae
Infections with group A strep can lead to Rheumatic Fever which in turn can damage heart valves. Valves on the right side are not as effected as often.
What criteria is used to diagnose rheumatic fever?
Jones Criteria
What are causes of aortic regurgitatation?
- Rheumatic Fever
- Infectious endocarditis
- Aortic Dilations - due to Syphilis, Rheumatoid arthritis, Marfans
Failure of the valve to close completely allows reverse flow. This leads to fluid volume overload on the heart.
What are causes of mitral regurgitatation?
- Mitral valve prolapse - seen commonly in Marfan’s disease
- Infections
- Fen-Phen an anti-obesity drug
- Papillary muscles following MI
- Infectious endocarditis
- Chordae tendinae can tear due to effects of RF or infectious endocarditis
- Calcification of mitral ring (occurs withe age)
When do congenital heart defects arise in utero?
3-8 weeks
What are the types of ASD?
- Secundum (90%): Defective fossa ovalis (near centre of atrial septum)
- Prium (8%): adjacent to AV valves, mitral cleft
- Sinus venous (2%): near entrance of SVC with anomalous pulmonary veins draining to SVC or RA
When an ASD is open in an adult, an embolus that would normally remain in the pulmonary system can now travel into the systemic system. The embolus could then present as a stroke, ischaemic bowl, distal extremity etc. This is described as a paradoxical embolus.
