HOCM Flashcards

1
Q

What is hyperrophic obstructive cardiomyopathy?

A
  • Autosomal dominant disorder of muscle tissue caused by defects in the genes encoding contractile proteins
  • Estimated prevalence is 1 in 500
  • HOCM is important as it is the most common cause of sudden cardiac death in the young
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2
Q

What is the pathophysiology of HOCM?

A
  1. Most common defects involve a mutation in the gene encoding β-myosin heavy chain protein or myosin-binding protein C
  2. Results in predominantly diastolic dysfunction
  3. Left ventricle hypertrophy → decreased compliance → decreased cardiac output
  4. Characterized by myofibrillar hypertrophy with chaotic and disorganized fashion myocytes (‘disarray’) and fibrosis on biopsy
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3
Q

What are the features of HOCM?

A
  • Often asymptomatic
  • Exertional dyspnoea
  • Angina
  • Syncope:
    • typically following exercise
    • due to subaortic hypertrophy of the ventricular septum, resulting in functional aortic stenosis
  • Sudden death (most commonly due to ventricular arrhythmias), arrhythmias, heart failure
  • Jerky pulse, large ‘a’ waves, double apex beat
  • Ejection systolic murmur:
    • increases with Valsalva manoeuvre and decreases on squatting
    • hypertrophic cardiomyopathy may impair mitral valve closure, thus causing regurgitation
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4
Q

What are diseases are associated with HOCM?

A
  • Friedreich’s ataxia
  • Wolff-Parkinson White
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5
Q

What are the ECHO findings of HOCM?

A
  • Mitral regurgitation (MR)
  • systolic anterior motion (SAM) of the anterior mitral valve leaflet
  • Asymmetric hypertrophy (ASH)
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6
Q

What are the ECG findings of HOCM?

A
  1. Left ventricular hypertrophy
  2. Non-specific ST segment and T-wave abnormalities, progressive T wave inversion may be seen
  3. Deep Q waves
  4. Atrial fibrillation may occasionally be seen
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7
Q

What is the management of HOCM?

A

Management:

Amiodarone

Beta-blockers or verapamil for symptoms

Cardioverter defibrillator

Dual chamber pacemaker

Endocarditis prophylaxis*

Drugs to avoid:

  • nitrates
  • ACE-inhibitors
  • inotropes
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8
Q

What is hypothermia?

A

Unintentional reduction of core body temperature below the normal physiological limits

  • Mild hypothermia: 32-35°C
  • Moderate or severe hypothermia: < 32°C
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9
Q

What are some causes of hypothermia?

A
  • Exposure to cold in the environment is the major cause
  • Inadequate insulation in the operating room
  • Cardiopulmonary bypass
  • Newborn babies.
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10
Q

What are risk factors of hypothermia?

A
  • General anaesthesia
  • Substance abuse
  • Hypothyroidism
  • Impaired mental status
  • Homelessness
  • Extremes of age
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11
Q

What are signs of hypothermia?

A
  • Shivering
  • Cold and pale skin. Frostbite occurs when the skin and subcutaneous tissue freeze, causing damage to cells.
  • Slurred speech
  • Tachypnoea, tachycardia and hypertension (if mild)
  • Respiratory depression, bradycardia and hypothermia (if moderate)
  • Confusion/ impaired mental state
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12
Q

What are signs of hypothermia in a newborn?

A
  • Babies with hypothermia can look healthy
  • However, they may be limp, unusually quiet and refuse to feed
  • Heat loss in newborns is extremely common, hence a hat and clothing/blankets will be applied soon after birth
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13
Q

What investigations needed in hypothermia?

A
  • Temperature: Special low-reading rectal thermometers or thermistor probes are preferred for measuring core body temperature. The patient’s temperature should be tracked over time, to check for improvement
  • 12 lead ECG: As the core temperature approaches 32°C to 33°C, acute ST-elevation and J waves or Osborn waves may appear
  • Bloods:
    • FBC, serum electrolytes
    • Haemoglobin and haematocrit can be elevated (due to haemoconcentration)
    • Platelets and WBCs are low due to sequestration in the spleen
    • Monitoring potassium is advised as hypothermic patients can be hypokalaemic due to a shift of potassium into the intracellular space
  • Blood glucose: Stress hormones are increased, and the body can have more peripheral resistance to insulin
  • Arterial blood gas
  • Coagulation factors
  • Chest X-ray
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14
Q

What is the initial management of hypothermia?

A
  • Removing the patient from the cold environment and removing any wet/cold clothing,
  • Warming the body with blankets
  • Securing the airway and monitoring breathing,
  • If the patient is not responding well to passive warming, you may consider maintaining circulation using warm IV fluids or applying forced warm air directly to the patient’s body
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15
Q

What is the danger of rapid rewarming in hypothermia?

A
  • Can lead to peripheral vasodilation and shock
  • In severe cases, be prepared to conduct CPR
  • IV drugs should be avoided if possible, as the patient is more likely to have a drastic response to the drug.
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16
Q

What should you not do in hypothermia?

A

Due to the risk of cardiac arrest:

  • Don’t put the person into a hot bath.
  • Don’t massage their limbs.
  • Don’t use heating lamps.
  • Don’t give them alcohol to drink.