Cardiomyopathy plus diabetes and the heart Flashcards
Definition of cardiomyopathy
Disease with the dominant feature being direct involvement of the myocardium.
Classification of cardiomyopathy
Functional
- Dilated
- Hypertrophic
- Restricted
Specific aetiology
- Ischaemic
- Hypertensive
- Inflammatory
- Alcoholic
- Post tachycardia
- Drug induced (e.g. daunorubicin, adriamycin, peripartum etc)
- Related to muscular or neuromuscular diseases
Dilated cardiomyopathy
Characterised by cardiac enlargement and reduced systolic function.
Although multiple diseases are known to cause it, most new cases are ‘idiopathic’.
All chambers (usually) enlarged with widespread fibrosis.
Presentation of DCM
- Symptoms of LVF principally SOBOE.
- Incidental finding of ECG changes often LBBB.
- Incidental finding of big heart on CXR
- Incidental big heart on echo or reduced LV function.
Management of DCM
Symptomatic: treat as LVF
- ACEI (or ARBs) and vasodilating beta blockers the key drug classes.
Asymptomatic: treatment not certain. Generally use vasodilating beta blockers (e.g. carvedilol)
Hypertrophic cardiomyopathy
HOCM (however, not all obstructive).
Familial HOCM: autosomal dominant with variable penetrance and expression.
- A number of genes are involved in development of HOCM including ones affecting myosin, others tropomyosin, others troponin T etc.
- Many sporidic cases are presumably spontaneous mutation.
Pathophysiology of HOCM
- Marked LVH often mainly septal
- Small LV cavity
- Often systolic anterior motion of MV
Septal LVH plus contribution from the MV movement may cause significant obstruction of LV outflow tract
Symptoms of HOCM
- Generally asymptomatic and often found by family screening after index case.
- Commonest symptom dyspnoea
- Angina, palpitations, dizziness may occur.
- Unfortunately sudden death may be first symptom or event
Examintion findings in HOCM
- Forceful apex beat sometimes a double impulse (palpable ‘a’ wave).
- Carotid pulse ‘jerky’
- Often 4th heart sound
- Mid-systolic murmur that changes with ‘vaso-active’ manouvres; increases with those that reduce venous return (smaller cavity magnifies LV outflow gradient) and decreases if LV volume increases.
- Longer systolic mumur if MR also present.
Complications of HOCM
- Sudden cardiac death (Commonest cause of SCD in adolescents)
- Ventricular and SV dysrhythmias
- CCD
- Mitral regurgitation
- Infective endocarditis
- AF tolerated poorly
Management of HOCM
- Echo confirms diagnosis
- NO hihly competitive sports
- If significantly symptomatic with LVOT gradient beta block and add if needed Ca channel blocker that reduces contractility such as verapamil
- These drug classes reduce contractility and lessen the LVOT gradient
- If gradient very large and patient very symptomatic surgical myomectomy (septal artery ablation sometimes used).
- Defibrillator for patients at high risk of SCD
Restrictive cardiomyopathy
Also called infiltrative cardiomyopathy
Least common form of CM.
Management very difficult.
Restrictie CM aetiology
Amyloid, sarcoid and ‘idiopathic’ most common aetiologies.
Often hard to diagnose aetiology, sometimes requiring biopsy and even then not always helpful.
Restrictive CM pathophysiology
Principal pathophysiology is diastolic dysfunction and sometimes there is minimal systolic dysfunction.
Type I diabetes and CVD risk
Increased CVD risk appears related to increased weight gain particularly central adiposity (?) due to peripheral hyperinsulinaemia.
Risk is increased because of adverse effects of diabetic microangiopathy especially renal.
