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14.02.12 Cardiology revision

Bacteria
  • Strep. pyogenes
    • = GAS
    •  => Rheumatic fever
  • Viridans Strep.
    • e.g. S. mutans (dental caries)
    • Unique ability to synthesize dextrans from glucose => fibrin-platelet aggregates at damaged heart valves
    • => Endocarditis

Rheumatic fever
  • Typically 5-15 years
  • Antigenic mimicry => Pancarditis
    • Endo-, Myo-, Peri-

RV Strain Pattern
  • Prominent R waves in V1, aVR
  • ST depression and T wave inversion in the leads corresponding to the right ventricle, i.e:
    • The right precordial leads: V1-3, often extending out to V4
    • The inferior leads: II, III, aVF, often most pronounced in lead III as this is the most rightward-facing lead

Jones Criteria for rheumatic fever
  • Evidence of recent streptococcal infection (eg history of scarlet fever, positive throat swab or rising or increased ASOT >200U/mL or DNase B titre)
  • Plus 2 major criteria, or 1 major and 2 minor criteria 
  • Major criteria - SPACE:
    • Subcutaneous nodules
    • (Peri)-Carditis (occurs in 40% of patients)
    • Arthritis
    • Chorea (also known as Sydenham's chorea and 'St Vitus' Dance')
    • Erythema marginatum
  • Minor criteria:
    • Fever
    • Raised ESR, CRP
    • Arthralgia 
    • Prolonged PR interval

Digoxin ECG changes
  • Major:
    • Downsloping ST depression with a characteristic “sagging” appearance
    • Flattened, inverted, or biphasic T waves
    • Shortened QT interval
  • Minor:
    • Mild PR interval prolongation of up to 240 ms (due to increased vagal tone)
    • Prominent U waves
    • Peaking of the terminal portion of the T waves
    • J point depression (usually in leads with tall R waves)
  • Exacerbated by hypokalaemia (competition for receptors or something)
  • Can treat with digibind

Aortic stenosis
  • Turbulent flow => Wear
  • Echo criteria:
    • Peak gradient
    • Peak velocity
    • Valve area
  • Symptoms (SAD):
    • Syncope (3 yrs survival)
    • Angina (5 years survival)
    • Dyspnoea (2 years survival)
  • No medical management improves survival

Papillary muscles
  • Five in total:
    • Anterior, posterior, and septal papillary muscles of the right ventricle each attach via chordae tendineae to the tricuspid valve
    • Anterior and posterior papillary muscles of the left ventricle attach via chordae tendineae to the mitral valve
  • In the LV:
    • Anterolateral papillary muscle more frequently receives two blood supplies
      • LAD, LCX
      • Therefore more frequently resistant to coronary ischemia
    • Posteromedial papillary muscle is usually supplied only by the PDA
      • Significantly more susceptible to ischemia


Graham Steell murmur

  • Typically associated with pulmonary regurgitation
  • High pitched early diastolic murmur heard best at the left sternal edge in the second intercostal space with the patient in full inspiration
  • Usually a consequence of pulmonary hypertension
    • Cor pulmonale
    • COPD
    • Secondary to MR

Carcinoid heart disease
  • Common in patients with carcinoid syndrome
    • Up to 50%
  • Characterised by right sided cardiac involvement
    • Caused by plaque-like deposits of fibrous tissue which are thought to be caused by serotonin, via action on the 5HT2b receptor
    • Most commonly seen on valve cusps and leaflets, but can be anywhere in the cardiac chambers
    • Left side of the heart is relatively protected, with the pulmonary circulation filtering out the majority of the serotonin produced by the tumour
  • Echocardiography demonstrates thickening of the tricuspid/pulmonary valve leaflets and sub-valvular apparatus
    • +/- Functional regurgitation and stenosis 

Ortner's syndrome 

  • Rare cardiovascular syndrome
  • RLN palsy from dilated LA due to MS/Pulmonary HTN/Thoracic aorta aneurysm

Notes
  • Erythema marginatum
    • Pink rings on the trunk and inner surfaces of the limbs 
    • Come and go for as long as several months
    • Primarily on extensor surfaces
  • IABP / Nitroprusside can buy time in MR before surgery but do not increase survival
  • HARD to exclude LA thrombus on TOE
  • IV flecainide contraindicated in LV impairment due to negative inotropic effects
  • WPW
    • Whatever you do, don't slow the AV node - e.g. CCBs/Adenosine
    • Propafenone / Flecainide can slow accessory pathway
  • Atrial tachycardia is distinct from sinus tachy - Ectopic atrial pacemaker (often near SA node)
  • Patient with Ca bowel
    • Strep. bovis can invade through bowel wall => Infective endocarditis
  • QTc is measured to the TANGENTIAL END OF THE T WAVE
    • QTc is prolonged if > 440ms in men or > 460ms in women
    • QTc > 500 is associated with increased risk of torsades de pointes
    • QTc is abnormally short if < 350ms
    • A useful rule of thumb is that a normal QT is less than half the preceding RR interval

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