Cardiology

Cardiomyopathies

The cardiomyopathies are a collection of diseases that predominantly affect myocardial function. By convention cardiomyopathy is generally excluded but the term Ischaemic cardiomyopathy is well understood. The main pure cardiomyopathies are hypertrophic, restrictive and dilated. They often have varying aetiologies - some are inherited, some possibly post viral, some related to toxins.  

Hypertrophic Cardiomyopathy

Introduction
  • Hypertrophic Cardiomyopathy is an autosomal dominant inherited disease with asymmetrical left ventricular hypertrophy and diastolic dysfunction.
  • There is a risk of arrhythmias and sudden death in 1% per year. Only 20% have LV outflow obstruction.

Aetiology

  • Genetic studies show that a point mutation in the gene encoding of sarcomeric contractile proteins leads to abnormal sarcomeric contractile proteins.
  • Mutations in at least one of at least 10 genes including Beta Myosin heavy chain, alpha tropomyosin, cardiac troponin T and I, myosin Binding protein C, actin, titin and Myosin Light chai
Associations (does not mean causation)
  • Mitral valve prolapse, phaeochromocytoma, Noonan's syndrome [(AD) Dysmorphic facial features + Pulmonary stenosis + mental retardation]
  • Fabry's disease - XL inherited lysosomal storage disease with infiltration with all types of cardiomyopathy deficiency of alpha galactosidase
  • Wolff Parkinson White syndrome

Clinical

  • Clinically in most patients the disease is asymptomatic and is only diagnosed in family screening following sudden cardiac death at PM in a relative or as part of a screening program for athletes.
  • Ask about dyspnoea due to diastolic dysfunction (rise in LVEDP) or syncope or pre syncope.
  • Palpitations due to AF or even VT can occur.
  • Jerky pulse, irregularly irregular pulse of AF, cardiac failure
  • Raised JVP - prominent 'a' wave due to forceful atrial contraction against a stiff right ventricle + S4.
  • Patients may have a double/triple apex beat and a pansystolic murmur due to Mitral regurgitation.
  • A late systolic murmur due to LV outflow track obstruction may occur.
  • The murmur intensity relates to LV size and volume.
  • Dynamic testing: A valsalva reduces cavity size and thus increases the murmur. Squatting decreases left ventricle preload and also increases the intensity of the murmur

Investigations

  • ECG - AF, LVH, deep T wave inversion, ST and deep Q wave "pseudoinfarction" appearance, abnormal.
  • Echo - Asymmetrical septal hypertrophy, systolic anterior movement of AMVL . Echo variants include apical hypertrophy seen in Asia. Main issue is differentiating HCM from normal athletic heart hypertrophy or simple hypertensive heart disease.
  • Cardiac MRI
  • Genetic studies may be appropriate in some

Management

  • Symptoms bare little relationship to the degree of LVOT obstruction.
  • Avoid Inotropes and some vasodilators e.g. Digoxin, Nitrates, Diuretics, Vasodilators, Beta agonists.
  • There is a wide spectrum of the disease from the benign nature to those at serious risk of sudden cardiac death.
  • Medications used include Beta blockers (propranolol), Verapamil or Disopyramide.
  • Antiarrhythmics which are negative inotropes resulting in further decrease in outflow gradient.
  • Atrial fibrillation - consider Warfarin to prevent cardiac emboli and Amiodarone for rate/rhythm control.
  • ACE inhibitors are not contraindicated but should be used with caution as they may increase LVOT gradient.
  • Alcohol septal ablation and surgical myomectomy
  • Other treatments - ICD may be indicated even as a bridge to cardiac transplantation in those at high risk

Dilated Cardiomyopathy

About

  • The heart becomes dilated with impaired contractile activity.

Aetiology

  • Myocardial damage leads to worsening cardiac output with a large flabby poorly contracting myocardium.

Causes

  • Alcohol , Beri-Beri, Ischaemic heart disease, Post partum, Viral,
  • HIV infections, chemotherapy and many are Idiopathic despite investigation.

Clinical

  • Symptoms of failure and palpitations.
  • There is cardiomegaly on clinical exam with a displaced apex
  • Raised JVP if in failure, tachycardia and possibly AF
  • A triple rhythm with S3 or S4 may be audible and a functional mitral regurgitation murmur.
  • Bibasal crackles and oedema if in failure.

Investigations

  • FBC, U&E, ESR, CRP, HIV test
  • Echocardiogram
  • Coronary angiography to look for treatable disease ? hibernating myocardium

Management

  • As for heart failure with cardiac rehab, ACE Inhibitors / ARB, Beta Blockers, Diuretics, Digoxin.
  • Some may need Amiodarone for Arrhythmias
  • Warfarin/NOAC for AF or cardioembolism
  • Consider ICD and Biventricular synchronised pacing may be appropriate
  • Cardiac transplantation is an option in younger patients with end stage failure though donor organs are in short supply.

Restrictive Cardiomyopathy

The "square root sign" at cardiac catheterisation can be seen in constrictive pericarditis, right ventricular myocardial infarction and restrictive cardiomyopathy)

About

  • A stiff heart impedes ventricular filling causing diastolic heart failure even though ventricular systolic function may be normal.

Aetiology

  • The intraventricular pressure at the end of filling is high (LVEDP) and this impairs LV filling.

Causes

  • Loeffler's fibrosis
  • Amyloid (ground glass myocardium. Low voltage ECG, Digoxin toxicity)
  • Sarcoidosis
  • Haemochromatosis and
  • Eosinophilic heart disease

Clinical

  • Worsening cardiac failure with dyspnoea and peripheral oedema
  • Atrial fibrillation

Investigations

  • Echo which may be bright with amyloid and give some signs of diastolic impairment and normal systolic function
  • ECG - AF, low voltage with amyloid and Cardiac MRI for amyloid
  • Catheterisation shows a "Square root sign" (dip and plateau).
  • In some cases an Endomyocardial biopsy may be indicated.

Management

  • Management is to treat as for diastolic heart failure mainly using diuretics.
  • Transplantation in end stage failure.