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Medicine year 2 semester 2 > Case 20-pathology > Flashcards

Case 20-pathology Flashcards

1
Q

Pulmonary embolism

A
  • Common
  • Pulmonary emboli are often multiple, representing fragments of the clot breaking off in the leg/pelvis
  • Size of pulmonary embolism does not matter
  • The pulmonary emboli can be asymptomatic
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2
Q

Development of a PE

A
  • Thrombus in the deep leg vein embolises
  • It travels back up through the IVC
  • Through the right atria, right ventricle
  • And out through the pulmonary arteries
  • Therefore the first small enough vascular bed the embolism meets is the pulmonary arteries, so it lodges here
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3
Q

Small pulmonary embolisms

A
  • Can be asymptomatic
  • Can lodge in smaller segmental arteries
  • Causing restriction in blood flow and nutrients to some pleura
  • Causing irritation of pleura
  • Symptoms = breathlessness, pleuritic pain, haemoptysis
  • Signs = pleural effusion, tachycardia, tachypnoea
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4
Q

Large pulmonary embolisms

A
  • Can be fatal
  • Symptoms = syncope, pre-syncope, chest pain, breathlessness
  • Signs = right sided heart failure due to increased work of the right ventricle, shock
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5
Q

The spiral of death

A

The more pulmonary arteries occluded the more dilated the Right ventricle

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6
Q

Natural history of pulmonary embolism

A
  • Vast majority will resolve (fibrinolysis gets to work)
  • Small proportion persist in 1-3%
  • Leading to chronic thromboembolic pulmonary hypertension (CTEPH)
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7
Q

Arterial thrombosis

A
  • Ruptured plaque and acute thrombus in a critical end artery
  • Myocardial infarction (MI)
  • Pain, breathlessness, nausea, sweating
  • Possible death from arrhythmia and or low output cardiac failure
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8
Q

Acute limb ischaemia

A
  • Clinical emergency
  • Can be caused by thrombosis (rupture of atheromatous plaque in a leg artery) OR
  • Embolism (from left atrium, if in AF)
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9
Q

The 4 P’s of Pulmonary embolism

A
  • Pain
  • Pallor
  • Pulseless
  • Perishing cold
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10
Q

Acute mesenteric (gut) ischaemia

A
  • More often embolic i.e. 2y to AF but can be primary thombotic in a Mesenteric artery
  • Diffuse, generalised abdominal pain usually with nausea and vomiting
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11
Q

Stroke

A
  • This can be primary thrombotic (atheromatous plaque rupture in supplying artery) or embolic (big worry in AF)
  • Features depend on which brain territory the blocked artery supplies
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12
Q

A blocked left cerebral artery causes

A
  • Right hemiplegia
  • Right hemianesthesia
  • Right homomymous hemianopia
  • Aphasia/dysphasia (if dominant side is left)
  • Drift of gaze to the left
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13
Q

Types of thromboses and embolisms

A

1) Arterial thrombosis
2) Arterial embolism
3) Paradoxical embolism
4) Fat embolism
5) Gas embolism
6) Amniotic fluid embolism

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14
Q

Arterial thrombosis, Arterial embolism, Paradoxical embolism

A

1) Arterial thrombosis- when a thrombosis occurs in a critical end artery. Occurs due to a ruptured atheroma
2) Arterial embolism- blood clot that breaks off and travels. Most commonly due to AF. Travels to leg/brain/gut etc
3) Paradoxical embolism- when a system embolus arises in a vein but ends up in arterial circulation. Most commonly due to patent foramen ovale

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15
Q

Fat embolism, Gas embolism, Amniotic fluid embolism

A

Fat embolism- freely floating fat globule in the blood stream. Can lodge and obstruct blood circulation in vital organs. Most commonly in the skin and brain. Usually caused by injury to subcutaneous tissue or a bone fracture that allows fat release. Fat globules can be released after orthopaedic surgery/trauma
Gas embolism- gas lodges in a vessel, represented by decompression sickness or caisson disease. Usually in the muscle, brain and skin
Amniotic fluid embolism- when amniotic fluid enters the maternal circulation during labour, very rare but serios.

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16
Q

Risk factors for venous thromboembolism

A
  • Very high risk- lower limb fracture, Hip/knee surgery, major trauma, previous VTE, Recent MI/heart failure
  • Moderate- Cancer, Chemotherapy, Latrogenic lines, Autoimmune disease, Oestrogen (OCP, post partum), Constant immobility, IBD, Infection (UTI, lung, HIV), Thrombophilia
  • Weak- obesity, DM, age, pregnancy
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17
Q

Risk factors for thrombosis and embolism

A

1) On the arterial side, conditions and factors linked to atheroma increase the risk of occlusive thrombosis.
2) Conditions and factors linked to AF increase the risk of arterial embolism.

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18
Q

Bleeding history

A
  • Onset of bleeding- was it spontaneous or after a haemostatic challenge like a dental extraction, surgery, postpartum
  • Location of bleeding- skin, mucus membranes, muscles, joints
  • Pattern of bleeding- bruises, petechiae, haematomas
  • Duration and severity of bleeding
  • Menstrual history
  • Treatment/interventions required to stop bleeding- local pressure, cautery/packing for nosebleeds, other interventions
  • History of symptoms of anaemia/iron deficiency- fatigue, prior iron supplements
  • Previous blood transfusions
  • Medication history
  • Family history of bleeding problems
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19
Q

Skin bleeding

A
  • Petechia (less than 3mm)- pin point areas of bleeding in subcutaneous tissues. Commonly caused by the rupture of small blood vessels and minor haemorrhage into the skin. More common in dependent areas such as lower legs. Less theb 30,000 platelets
  • Purpura- between 3mm and 1 cm
  • Ecchymoses- greater than 1 cm
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20
Q

Mucosal bleeding

A

Epistaxis, Gum bleeding, Blood blisters

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21
Q

Other parts of the examination for a bleeding disorder

A
  • Signs of anaemia
  • Joint examination- haemophilia A or B can cause haemorrhage into the joints
  • Examination of lymph node, spleen and liver
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22
Q

Screening tests for Hemostasis

A
  • Full blood count including platelet count
  • Peripheral blood smear examination
  • Prothrombin time (PT)
  • Activated partial thromboplastin time (APTT)
  • Bleeding time or PFA-100= sensitive to aspirin, monitors antiplatelet drug therapy. Screens patients for Von Willebrand disease and platelet function disorders
  • Thrombin time
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23
Q

Other specialised tests for clotting disorders

A
  • Mixing studies or prolonged PT or APTT. Helps determine which factor is deficient. Mixes the patients blood with normal blood
  • Coagulation factor assays
  • Platelet function testing
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24
Q

Quantitative Platelet disorders

A
  • Thrombocytopenia (decreased)

* Thrombocytosis (increased)

25
Q

Platelet disorders Qualitative

A
  • Hereditary- rare (i.e. Glanzmann disease- absent GP2b/3a), Bernard-Soulier disease absent GP1b
  • Acquired- drugs i.e. aspirin, clopidogrel, liver/renal failure
26
Q

Isolated thrombocytopenia

A
  • Decreased synthesis= Bone marrow failure i.e. aplastic anaemia, leukaemia, drugs
  • Increased consumption- infection/DIC
  • Increased destruction= Idiopathic Thrombocytopenic Purpura (ITP), Splenomegaly
27
Q

Typical bleeding symptoms of Quantitative Platelet disorders

A
  • Spontaneous kin purpura and haemorrhage
  • Mucocutaneous bleeding
  • Prolonged bleeding after trauma
  • Epistaxis
  • Menorrhagia
28
Q

Idiopathic thrombocytopenic purpura (ITP)

A
  • Autoimmune disorder
  • Diagnosis of exclusion- exclude causes such as alcohol, drugs, liver disease, infection (HIV and Hep C) and primary haematological disorders and secondary causes i.e. conductive tissue disorders such as SLE
  • Childhood ITP- often associated with infection and is self limiting
  • Antiplatelet autoantibodies lead to reduced survival and removal of platelets by RES (spleen and liver)
29
Q

Labs in ITP

A
  • Platelets <100 x 10^9/l
  • Hb and WBC normal
  • Large platelets on blood film- normal PT/APTT
  • Bone marrow shows a normal number of megakaryocytes relative to overall cellularity
30
Q

Treatment in ITP

A
  • With platelets greater than 30 x 10^9/L with no bleeding can be managed with observation alone
  • In childhood ITP, in up to 80% of cases it resolves within 6 months with no treatment
  • Most adults will require treatment as spontaneous remissions are rare
  • 1st line= Dexamethasone (pulse), Prednisone (taper), IVIG
  • 2nd line= Splenectomy, Rituximab, TPO receptor agonists
  • Immunosuppressant medication
31
Q

Qualitative platelet disorders

A

Platelet count may be adequate but bleeding is due to abnormal platelet function
• Inherited- Glanzmanns thrombasthenia (affects glycoproteins IIb/IIIa), Bernard Soulier syndrome (abnormalities in the glycoproteins Ib/IX/V), storage pool disorders (issues with platelet granules). May be difficult to diagnose so family studies are needed
• Acquired- Aspiring ingestion, uraemia and in myeloproliferative disorders

32
Q

Disorders of secondary Haemostasis Pathogenesis:

A
  • Decreased factor production- Acquired (tends to be multiple factors i.e. in liver cirrhosis), inherited (usually single factors
  • Pathologic inhibition of coagulation factors- factor inhibitors
  • Excessive consumption of factors (DIC)
33
Q

Xa-Va complex

A

The factor Xa that is formed can complex with the partially active factor released from platelets; this factor Xa-Va complex converts prothrombin to thrombin.

34
Q

Coagulation factor disorders symptoms

A
  • Lifelong bleeding tendency
  • Bleeding with operations and trauma
  • Joint haemarthroses and muscle haematomas are typical in severe Haemophilia A and B
  • Coagulation screen test abnormalities
  • Confirmatory tests include factor assays and genetic testing
  • Intercranial bleeds can cause morbidity and mortality
35
Q

Blood results in Haemophilia A/B

A

Genetic variant in factor 8 or 9 leading to low plasma levels. Blood results:
• Prolonged APTT (intrinsic pathway)
• Normal PT
• Decreased factor VIII

36
Q

Haemophilia B (Christmas disease)

A

The features are the same as Haemophilia A but the factor is 0
• X linked recessive, predominantly in males
• De novo mutation= 30% of cases, arises without family history
• All the sons of affected males are normal and their daughters are carriers
• 5% of female carriers have low levels of F8/9 due to skewed lyonisation of X-chromosome
• Pregnancy in known carriers means you need to manage the delivery of male babies to reduce risk of ICH (intracranial haemorrhage)
• When a carrier has a baby there is a one in two chance she will pass on the haemophilia gene. If it goes to the son he will have the condition, if it goes to the daughter she will be a carrier
• Females can have the disease but its very rare

37
Q

Clinical presentation in haemophilia A and B

A
  • Mild- may remain undetected until later in life. Few or no bleeding. Mild bleeding with challenges
  • Moderate- late onset, bleeding with trauma or surgical procedure
  • Severe- early onset even before two years of age. Presents with spontaneous bleeding into muscle or joints
38
Q

Treatment of Haemophilia

A
  • Administration of the deficiency clotting factor (replacement therapy)
  • On demand treatment- at time of bleeding
  • Regular prophylactic treatment- prevents bleeding episodes
  • Standard of care for severe haemophilia
39
Q

Von Willebrand disease (VWD)

A
  • Commonest inherited bleeding disorder= 1/1000
  • Autosomal dominant inheritance
  • Usually mild bleeding disorder
  • Due to reduced levels of von Willebrand factor
  • Mucocutaneous bleeding, bruising, post-op bleeding, bleeding from minor wounds, menorrhagia, post-partum bleeding
40
Q

Personal and family history of dyslipidaemia

A
  • Symptoms= dyspnoea, angina or claudication. Thirst or polyuria, muscle or joint pains
  • Concomitant disease
  • Smoking habits: current and past
  • Alcohol use: units per week
  • Exercise: active or inactive
  • Diet- dietician assessment
  • Past medical history: age at menopause
  • Family history: CVD, age at first event and vital status
  • Medication: including previous lipid modifying therapy
41
Q

Clinical examination- Dyslipidaemia

A
  • Height, weight- BMI (Kg/m^2), waist circumference
  • Dipstick urinalysis- proteinuria
  • Inspect for stigmata of hyperlipidaemia= eyes, Achilles and digital extensor tendons, knees and elbows, Palms and flexures
  • Cardiovascular examination- heart sounds, pulses, bruits
  • Blood pressure
42
Q

Basic serum lipid measurements

A
  • Total cholesterol- includes both atherogenic (LDL-C, IDL-C and VLDL-C) and anti-atherogenic fractions (HDL-C)
  • HDL-cholesterol- anti-atherogenic fraction, essential for risk assessment
  • Triglycerides- not considered directly atherogenic but is a risk modifier, a component of the “Metabolic syndrome”, sentinel marker of secondary hyperlipidaemias, risk factor for pancreatitis, 12h fasting triglycerides <4.5 required for calculation of LDL-C
43
Q

Calculates lipid variables

A 
• LDL cholesterol- considered the most important class of atherogenic lipoproteins; calculated using the Friedewald equation: (LDL-C = TC – (HDL-C + TG/2.2)
• Non- HDL cholesterol= Total atherogenic lipoproteins, alternative to LDL-C which can be used when TG are elevated or patient is non-fasting, simpler to calculate than LDL-C: (Non-HDL-C = TC – HDL-C)
• LDL cholesterol is important for diagnosis Familial Hypercholesterolaemia
• Non HDL cholesterol is preferred for assessment of response to therapy
Calculations of LDL-C assumes a constant cholesterol/TG ratio in VLDL which requires fasting to ensure the absence of prostprandial lipoproteins, including chylomicrons and chylomicron remnants.
44
Q

Measuring Apoliproteins

A

• Apolipoprotein A1- the main structural and functional apolipoprotein of the non atherogenic HDL particles each of which may contain multiple copies. ApoA1 concentration correlates with HDL-C
• Apolipoprotein B- each of the atherogenic lipoproteins LDL, IDL and VLDL contains one copy of the apolipoprotein B100 Chylomicrons (CM), CM remnants contain apolipoprotein B48 (truncated form)
• Lipoprotein (a)- a highly atherogenic modified form of LDL with the polymorphic plasminogen like apilopoprotein(a) covalently linked to apolipoproteinB100
• Apolipoproteins can be used to assess risk and as treatment targets
The two most common risk factors for stroke are smoking and dyslipidaemia ApoB/ApoA1 ratio

45
Q

Secondary dyslipidaemia

A
  • Diabetes- VLDL
  • Untreated hypothyroidism- LDL
  • Alcohol excess- VLDL
  • Obesity- VLDL
  • Chronic renal failure- VLDL/LDL
46
Q

Investigations for excluding hyperlipidaemia

A
  • Renal profile (Na+, K+, creatinine, eGFR)- Renal failure
  • Liver profile (TProt, Alb, ALP, ALT, GGT)- Cholestasis, M protein
  • Thyroid profile (TSH, FT4)- Hypothyroidism
  • Glucose (fasting) or HbA1c- diabetes
  • Dipstick urinalysis (protein)- Nephrotic syndrome
47
Q

Familial Hypercholesterolaemia

A
  • Mechanism- reduction in receptor mediated clearance of LDL. Due to mutation in LDLR, APOB or PCSK9 gene
  • Prevalence- 1 in 250
  • Lipid profile- Elevated LDL-cholesterol, TC 9-12 mmol/L. Low normal fasting triglycerides
  • Inheritance= autosomal co-dominant
  • Physical signs- Tendon Xanthomas, corneal arcus Homozygotes (ulcer)- also planar digital and natal cleft cutaneous xanthomas, aortic stenosis
  • CHD risk- very high
48
Q

Familial lipoprotein disorders in patients with premature coronary artery disease

A
  • Elevated lipoprotein
  • Hypertriglyceridaemia with low HDL
  • Familial combined hyperlipidaemia
  • Hyperapobetalipoproteinaemia
  • Familial Hypoalphalipoproteinaemia (low HDL-C)
  • Familial hypercholesterolaemia
  • Familial Hypertriglyceridaemia
49
Q

Diagnostic criteria for Heterozygous Familial Hyperlipidaemia

A

FH definite if 1 + (2 or 3) are present, possible if 1 + (4 or 5)

  1. Total cholesterol above 7.5mmol/l or LDL cholesterol above 4.9mmol/l in an adult (levels either pre-treatment or highest on treatment). Total cholesterol above 6.7mmol/l or LDL cholesterol above 4.0mmol/l in a child aged under 16 years
  2. Tendon xanthomas in patient, 1st degree relative (parent, sibling, child), or 2nd degree relative (grandparent, uncle, aunt)
  3. DNA-based evidence of an LDL receptor mutation, familial defective apo B-100, or a PCSK9 mutation.
  4. Family history of premature myocardial infarction : below age of 50 years in 2nd degree relative or below age 60 years in 1st degree relative
  5. Family history of raised total cholesterol: above 7.5mmol/l in adult 1st or 2nd degree relative or above 6.7mmol/l in child or sibling aged under 16 years.
50
Q

Familial combines hyperlipidaemia

A
  • Mechanism- overproduction of VLDL and apolipoprotein B. Genetic cause unknown probably multigenic
  • Prevalence- 1 in 100
  • Lipid profile- Elevated LDL cholesterol and/or triglycerides. TC 6.5-10mmol/L, TG 2.3-6.0 can be higher. Frequent low HDL- cholesterol. Non-HDL cholesterol/ApoB ratio <5. VLDL cholesterol/total TG ration <0.69
  • Inheritance- complex, some appear like autosomal dominant
  • Physical signs- non-specific, xanthelasma
  • CHD risk- high
51
Q

Familial combined Hyperlipidaemia- should be suspected in:

A
  • An individual with moderate to severe mixed hyperlipidaemia
  • Typical serum total cholesterol 6.5-10 mmol/l and serum triglycerides. TG 2.3-6 mmol/l
  • A personal or family history of hyperlipidaemia or premature CHD (not due to familial hypercholesterolaemia)
52
Q

Familial Hyperlipidaemia- test results

A
  • Isolated raised TG (VLDL) with or without low HDL-C
  • Mixed hyperlipidaemia or isolated elevation of LDL-C
  • Hypertension with hypercholesterolaemia
  • Familial dyslipidaemic hypertension
53
Q

Remnant (type III) hyperlipidaemia i.e. familial dysbetalipoproteinaemia

A
  • Mechanism- reduction in receptor mediated remnant clearance. Homozygosity for ApoE2 isoform and additional factors
  • Prevalence- 1 in 5000
  • Lipid profile= Total cholesterol 8-16 mmol/L (high). Triglycerides 4.5-9 can be higher. Cholesterol enriched ‘beta VLDL’ (remnants) present. Non-HDL cholesterol/ApoB ratio >5. VLDL-cholesterol/Total TG ratio >0.69
  • Inheritance- autosomal recessive, low penetrance
  • Physical sign- striate palmar and tuberoeruptive, xanthomata
  • CHD risk- very high, also high risk of peripheral and cerebrovascular disease
54
Q

Test results for FH, FCH and type III

A

FH- high total cholesterol, LDL-C, ApoB
FCH- high total cholesterol (lower then FH), TG, LDL-C, ApoB
Type III- high total cholesterol, TG and no LDL-C

55
Q

Familial Hypertriglyceridaemia

A
  • Mechanism- mild forms probably multigenic, more severe forms often monogenic i.e. lipoprotein lipase or apoCII deficiency
  • Prevailence- mild forms are 1 in 300, the severe forms are rarer
  • Lipid profile- elevated triglycerides, TG 2.3-10 in mild/moderate. In severe TG>10mmol/L, can be >100mmol/L. Usually apolipoprotein B (<1.3 g/L). Small, dense LDL (pattern B on gradient gel). Low HDL-cholesterol frequent (except excess alcohol)
  • Inheritance- mild forms overlap with FCH, severe forms usually autosomal recessive
  • Physical signs- eruptive xanthomas, lipaemia retinalis in severe
  • CHD risk- variable, severe forms prone to pancreatitis, metabolic syndrome, diabetes mellitus
56
Q

Summary of Hyperlipidaemia

A
  • Hyperlipidaemia may be primary or secondary (caused by a disorder of systems other than the lipid transport system e.g. thyroid)
  • Familial Hypercholesterolaemia and Familial Type III hyperlipidaemia cause severe early onset atherosclerosis
  • FCH is usually less severe but is much commoner and is linked to other risk factors such as hypertension, obesity and diabetes
  • Severe hypertriglyceridaemia can cause acute pancreatitis
57
Q

Characteristics of primary haemostasus

A

Timing of bleeding- immediate

Mucus membrane bleeding, Epistaxis, Petechiae, Ecchymoses

58
Q

Characteristics of secondary haemostasis

A

Timing of bleeding- delayed

Deep haematomas, joint bleeding

Medicine year 2 semester 2 (47 decks)

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