11.myocardium pdf - د. صباح

Medicine Dr.Sabah

DISEASES OF THE MYOCARDIUM

1-  MYOCARDITIS
2-  CARDIOMYOPATHY
3-  SPECIFIC DISEASES OF HEART MUSCLE

Z Myocarditis' and ‘Cardiomyopathy‘
Z conditions that primarily affect heart muscle

TYPES:

1- ACUTE-MYOCARDITIS, VIRAL, NON-VIRAL
2- ”CHRONIC”-CARDIOMYOPATHY, PRIMARY(IDIOPATHIC) & SECONDARY

TYPES   DILATED
a.  HYPERTROPHIC,
b.   RESTRICTIVE,
c.   OBLITERATIVE,
d.    ARVD

ACUTE MYOCARDITIS:

Acute inflammatory condition complicating wide variety of infections

Aetiology:

1. infection of myocardium
2. effects of circulating toxins.

Viral infection - most common cause esp.

Coxsackie viruses (35 cases per 1000 infections)
influenza viruses A and B (25 cases per 1000 infections).

Direct effect

Several weeks after initial viral infection

susceptibility is increased by corticosteroid treatment, immunosuppression, radiation,
previous myocardial damage , exercise.

Bacterial and Protozoal infections .e.g. Lyme disease (Borrelia burgdorferi, )

Clinical picture

Symptomless

------

1.  fulminant heart failure
2.  inappropriate tachycardia
3.  abnormal ECG
4.  may be heralded by a 'flu'-like illness.

Investigations

a. ECG: changes , common - non-specific.
b. Biochemical markers of myocardial injury (e.g. troponin I and T, creatine kinase) -

elevated in proportion to extent of damage.

c. Echocardiography - left ventricular dysfunction - sometimes regional (due to focal

myocarditis), if diagnosis is uncertain-can be confirmed by endomyocardial biopsy.

Outcome:

1) self-limiting- Most cases immediate prognosis = excellent.
2) death – ventricular arrhythmia, rapidly progressive heart failure. cause of sudden and

unexpected death young athletes.

3) chronic low-grade myocarditis or dilated cardiomyopathy ; e.g., in Chagas disease .(some

forms ) patient frequently recovers from acute infection but goes on to develop a chronic
dilated cardiomyopathy 10 or 20 years later

Treatment

A.  Most cases = only supportive therapy .
B.    Specific antimicrobial therapy = used if a causative organism has been identified- rare
C.  Treatment for cardiac failure or arrhythmias
D.  Avoid intense physical exertion = can induce potentially fatal ventricular arrhythmias.
E.  No benefit from corticosteroids and immunosuppressive agents.

CARDIOMYOPATHY:

TYPES

CAUSES

CLINICAL MANIFESTATIONS

INVESTIGATIONS

TREATMENT

Definition:

Group of diseases that primarily affect heart muscle

Not the result of
-  congenital HD
-  acquired valvular HD
-  hypertensive HD
-  coronary arterial D
-  pericardial abnormalities.

The diffuse myocardial fibrosis that accompanies multiple myocardial scars produced by
myocardial infarctions can impair left ventricular (LV) function and is frequently referred to
as ischemic cardiomyopathy.

use of the term cardiomyopathy should be avoided; instead, term restricted to a condition
primarily involving the myocardium.

Clinical Classification:

1) Dilated: Left and/or right ventricular enlargement, impaired systolic function, congestive

heart failure, arrhythmias, emboli

2) Hypertrophic: Disproportionate left ventricular hypertrophy, typically involving septum more

than free wall, with or without an intraventricular systolic pressure gradient; usually of a
nondilated left ventricular cavity

3) Restrictive: Endomyocardial scarring or myocardial infiltration resulting in restriction to left

and/or right ventricular filling

Aetiology:

most intrinsic disorders of myocardium has not been elucidated  functional

classification.

Morphologic types

1.  Dilated
2.  Hypertrophic
3.  Restrictive

1- DILATED CARDIOMYOPATHY:

Characterised by

a.  dilatation and impaired contraction of left (sometimes right) V
b.   left ventricular mass is increased but wall thickness is normal or reduced).
c.   histological changes = myofibrillary loss, interstitial fibrosis and T-cell infiltrates.

differential diagnosis = coronary artery disease and some specific disorders of heart muscle
, diagnosis of dilated cardiomyopathy =when these conditions have been excluded.

Pathogenesis-

1- Alcohol
2- Heridity: 25% of cases are inherited - autosomal dominant trait and a variety of single gene

mutations have been identified. mutations affect proteins in the cytoskeleton of the
myocyte

3- Autoimmune- late autoimmune reaction to viral myocarditis substantial subgroup of

patients with dilated cardiomyopathy; 10% of patients with advanced HIV infection

Clinical manifestations

a.  Arrhythmia
b.  Thromboembolism
c.  Heart failure
d.  Sudden death
e.   sporadic chest pain

Incidence & Prevelance

u  In North America and Europe, symptomatic dilated cardiomyopathy
       incidence = 20 per 100 000
       prevalence =38 per 100 000.
u   Men are affected > twice as often as women.
u  Most patients present with heart failure or
u  found to have condition during routine investigation.

1.  The ECG =non-specific changes
2.  Chest X-ray=cardiomegaly
3.   Echocardiography =establish  diagnosis.

Treatment

  controlling resulting heart failure.
  prognosis = variable
   cardiac transplantation may be indicated.
  Patients with dilated cardiomyopathy and moderate or severe heart failure -- at risk of

sudden arrhythmic death.—

   risk is substantially reduced by rigorous medical therapy 
    β-blockers and Angiotensin receptor antagonists.
  Some patients may be considered for implantation of  cardiac defibrillator and/or
   cardiac resynchronisation therapy

2- HYPERTROPHIC CARDIOMYOPATHY:

Most common form of cardiomyopathy

prevalence =approximately 100 per 100 000

Characterised by

1- inappropriate and elaborate left ventricular hypertrophy
2- malalignment of myocardial fibres.

Pattren of hypertrophy
a. Generalised (concentric) or
b. Confined (Focal) largely to interventricular septum (asymmetric septal hypertrophy,)

apical hypertrophic cardiomyopathy

Aetiology

1. genetic disorder autosomal dominant transmission, a high degree of penetrance and

variable expression. single point mutation in one of the genes that encode sarcomeric
contractile proteins.

2. Beta-myosin heavy chain mutations = elaborate ventricular hypertrophy.
3. Troponin mutations = little, and sometimes even no hypertrophy but marked myocardial

fibre disarray, an abnormal vascular response (e.g. exercise-induced hypotension) and a high
risk of sudden death.

4. Myosin-binding protein C mutations = hypertension and arrhythmia.

Pathophysiology

]

Stiff non-compliant ventricles impede diastolic filling Heart failure

]

Septal hypertrophy  dynamic left ventricular outflow tract obstruction (hypertrophic
obstructive cardiomyopathy, or HOCM) and Abnormal systolic anterior motion - anterior MV
valve leaflet

]

Mitral regurgitation-

Clinical manifestations

 Effort-related symptoms

a.  angina
b.  breathlessness
c.  arrhythmia
d.  sudden death

 Symptoms and signs are similar to those of aortic stenosis, (except that in HCM , character of

the arterial pulse is jerky).

CLINICAL FEATURES OF HYPERTROPHIC CARDIOMYOPATHY:

W Symptoms

1.  Angina on effort
2.  Dyspnoea on effort
3.  Syncope on effort
4.  Sudden death

W Signs

1)  Jerky pulse*
2)  Palpable left ventricular hypertrophy
3)  Double impulse at the apex (palpable fourth heart sound due to left atrial hypertrophy)
4)  Mid-systolic murmur at the base*
5)  Pansystolic murmur (due to mitral regurgitation) at  apex

Investigations

1. ECG



features of left

ventricular hypertrophy with
a wide variety of often bizarre
abnormalities (e.g. pseudo-
infarct pattern, deep T-wave
inversion).

2. Echocardiography 

diagnostic;
diagnosis = difficult when
another cause of left ventricular
hypertrophy is present (e.g.
physical training-athletes'
heart, hypertension) but the degree of hypertrophy is greater than expected.

3. Genetic testing may facilitate diagnosis in the future.

Outcome

natural history = variable but clinical deterioration is often slow.

annual mortality from sudden death = 2-3% among adults , 4-6% in children and
adolescents.

Sudden death

typically occurs during or just after vigorous physical activity

hypertrophic cardiomyopathy = most common cause of sudden death in young athletes.

Ventricular arrhythmias = thought to be responsible for many of these deaths.

RISK FACTORS FOR SUDDEN DEATH IN HYPERTROPHIC CARDIOMYOPATHY:

1)  A history of previous cardiac arrest or sustained ventricular tachycardia
2)  Recurrent syncope
3)  An adverse genotype and/or family history
4)  Exercise-induced hypotension
5)  Multiple episodes of non-sustained ventricular tachycardia on ambulatory ECG monitoring
6)  Marked increase in left ventricular wall thickness

Treatment of hypertrophic CMP:

g Beta-blockers + rate-limiting calcium antagonists (e.g. verapamil) =
g  relieve angina
g  prevent syncopal attacks;
g No pharmacological treatment -definitely known to improve prognosis.
g Arrhythmias = common and often respond to amiodarone.
g Outflow tract obstruction = improved

- by partial surgical resection (myectomy) or
- by iatrogenic infarction of basal septum (septal ablation) using a catheter-delivered

alcohol solution.

g Implantable cardiac defibrillator (ICD) = in patients with clinical risk factors for sudden

death).

g Avoid Digoxin and vasodilators = increase outflow tract obstruction

3- RESTRICTIVE CARDIOMYOPATHY

*  rare condition
*   ventricular filling is impaired because the ventricles are 'stiff'.
*   high atrial pressures with atrial hypertrophy, dilatation   atrial fibrillation.
*  Amyloidosis =most common cause of restrictive cardiomyopathy in UK
*   other forms of infiltration (e.g. glycogen storage diseases), idiopathic perimyocyte fibrosis

and a familial form of restrictive cardiomyopathy can present with this form of heart disease.

*  Diagnosis can be very difficult and may require complex
*  Doppler echocardiography, CT or MRI, and endomyocardial biopsy.
*   Treatment is symptomatic but the prognosis is usually poor and transplantation may be

indicated.

4- ARRHYTHMOGENIC RIGHT VENTRICULAR DYSPLASIA

  Patches of the right ventricular myocardium are replaced with =fibrous and fatty tissue).
   inherited as an autosomal dominant trait.
  prevalence in the UK - approximately 10 per 100 000.
  clinical problems

-  ventricular arrhythmias,
-  sudden death
-  right-sided cardiac failure.

   ECG =  slghtly braodened QRS  and  inverted T waves in Rprecordial leads.
  MRI =useful diagnostic tool -used to screen the first-degree relatives of affected individuals.
   Patients at high risk of sudden death can be offered an ICD.

5- OBLITERATIVE CARDIOMYOPATHY:

 Endocardium of one or both ventricles
 characterised by thrombosis and elaborate fibrosis with gradual obliteration of the

ventricular cavities (e.g. endomyocardial fibroelastosis,)

 Regurgition of mitral and tricuspid valves.
 Clinicsl features

1.  Heart failure
2.  pulmonary and systemic embolism.
3.  sometimes be associated with eosinophilia (e.g. eosinophilic leukaemia, Churg-Strauss

syndrome,).

 In tropical countries= responsible for up to 10% of cardiac deaths. Mortality is high (50% at 2

years).

 Treatment

-  Anticoagulation and antiplatelet
-  diuretics may help symptoms of heart failure.
-  Surgery (tricuspid and/or mitral valve replacement with decortication of the

endocardium)

SPECIFIC DISEASES OF HEART MUSCLE:

C Infections

-  Viral, e.g. Coxsackie A and B, influenza, HIV
-  Bacterial, e.g. diphtheria, Borrelia burgdorferi
-  Protozoal, e.g. trypanosomiasis

C Endocrine and metabolic disorders e.g. Diabetes, hypo- and hyperthyroidism, acromegaly,

carcinoid syndrome, phaeochromocytoma, inherited storage diseases

C Connective tissue diseases e.g. Systemic sclerosis, systemic lupus erythematosus (SLE),

polyarteritis nodosa

C   Infiltrative disorders e.g. Haemochromatosis, haemosiderosis, sarcoidosis, amyloidosis
C   Toxin e.g. Doxorubicin, alcohol, cocaine, irradiation
C   Neuromuscular disorders e.g. Dystrophia myotonica, Friedreich's ataxia .