Week 10- CHD

Question 1

What is CHD?

Answer 1

CHD is a condition where the vascular
supply to the heart is obstructed by
atheroma, thrombosis or spasm

Question 2

What are the consequences of obstructed blood supply to the heart and what complications could it lead to?

Answer 2

Obstructed/Inadequate blood supply leads to lower levels of O2 to the heart which —–> ischaemic chest pain (IHD - ischaemic heart disease)

Complications it lead to

Inadequate blood supply   O2 supply
to the heart  ischaemic chest pain
(IHD= Ischaemic Heart Disease) &
depending on extent, can cause:
* Stable angina
* Acute Coronary Syndrome (ACS)
(MI + Unstable angina)
* Sudden death

Question 3

Describe the epidemiology of CHD

Answer 3

• • More common in males
• • About 15-20% die in UK
• S.Asians have increased ~45% increased risk of death
• Black African Caribbean have ~ 50% decreased risk

Question 4

Describe one of the causes (aetiology) of CHD

Answer 4

• Atherosclerosis ( see week 9 flashcard as model answer)
• Inflammatory process caused by damage to endothelium layer which increases oxidised lipoproteins permeability causing the efflux of macrophaes to the site and biuld up of lipid foam cells creating fatty streaks
• Collagen, elastin & glycoproteins secreted by SMC
• Leads to narrowing of blood vessel decreasing blood flow and increasing pressure leading to further damage

Question 5

How is a clot formed ( post atherosclerosis)

Answer 5

• Rupturing of plaque formed from athereosclerosis

Question 6

Describe some of the risk factors associated with CHD

Answer 6

– Age
– Gender
– FH
– Smoking
– Diet
– Obesity
– HT
– Hyperlipidaemia

Question 7

Why is a CV risk assesssment and carried out and what tool is used according to the NICE guidelines

Answer 7

• Carried out primary prevention ( lifestyyle interventions ) and is indicative if medicinal treatment is required
• Treat if >10%
• If already have CVD then assessment not
  applicable ⇒ assume high risk and treat

Question 8

Describe the pathophysiology of CHD and how chest pain is as a result of it

Answer 8

CHD physiologically consequents in an Imbalance between O2 demand and supply ( this causes the chest pain)

The following are dependant on **O2 demand **
– Heart rate , contractility & systolic wall tension

• The following are dependant on O2 supply

– coronary blood flow & O2 carrying capacity of
blood

• When the O2 supply cannot meet the demand there is a result of chest pain

Question 9

Describe how stable angina is caused and how exacerbations are provoked

Answer 9

Narrowing of coronary arteries due to plaque in the blood vessels leads to:

• chest pain typically provoked by:
  Exercise
  Stress
  Heavy meals
  Extremes of temperature
• relieved by rest or s/l GTN (spray)

Question 10

• Stable angina

Question 12

Describe the clinical symptoms of stable angina

Answer 12

– Central crushing chest pain
– May radiate to jaw, neck, back or arms
– “Constricting”, “choking”, “heavy weight”,
or “stabbing”, “burning” or “like a knife”

Question 13

Describe how stable angina is diagnosed

Answer 13

Defined by being induced by exercise etc & relieved by
rest/ GTN
– Lack of ECG / cardiac enzymes changes

Question 14

What is acute coronary syndrome ?

Answer 14

Acute coronary syndrome is used to define

• Myocardial Infarction (MI)
  either be ST elevated -MI (STEMI)
• or NSTEMI

And used define Unstable Angina (Troponin positive Acute Cardio syndrome)

Question 15

How is a Differential diagnosis made

Answer 15

• History of chest pain ( to determine root of it if it is gastric or heart related)
• increased presence of cardiac enzymes

Question 16

Describe how one way differential diagnosis is made for STEMI

Answer 16

In a ST elevated MI on the ECG the ST area on the ECG is raised closer to the peak

• NOT seen in NSTEMI & Unstable Angina

Question 17

Describe a ACS differential diagnosis is made using blood tests and describe how they help with diagnosis

Answer 17

• Blood tests measuring cardiac enzymes TROPONIN levels (T/I) - specific to myocardic cells
• Released after 2-4 hrs, peaks at 12 hrs & can persist up to 7 days

– Measured on admission

– Standard Troponin assays – repeated after 10-12 hrs

Question 18

Explain why highly sensitive Troponin assay is used as a diagnostic measure ACS

Answer 18

High sensitivity Troponin assays done after 3 hrs can rule out NSTEMI if ECG doesn’t show elevated wave.

Question 19

Why are troponin levels significant during a differential diagnosis between Unstable angina and MI?

Answer 19

During a STEMI/NSTEMI => ↑ Troponin >99th
percentile cut-off/upper reference limit

However during unstable angina some change in Troponin level but does not meet criteria for MI

Question 21

What is the criteria for troponin for ACS diagnosis

Answer 21

<0.4ng/ml => ACS unlikely

Question 22

Aside from MI what are other causes for increased troponin levels?

Answer 22

• Pulmonary embolism
• heart failure
• CKD
• Sepsis