Myocarditis Quiz

Aortic Valve Stenosis

• Results from minor to severe degrees of aortic valve maldevelopment or thickening
• One of 4 subtypes of left ventricular outlet obstruction (LVOT)
• Presentation depends on the severity of the obstruction
• Most patients are asymptomatic
• Older patients may present with chest pain or syncope
• In the neonatal period, those with critical aortic stenosis and duct-dependent systemic circulation may present with severe heart failure leading to shock
• A subset of patients present with poor left ventricular function, low cardiac output, and signs of shock and congestive heart failure ('critical' aortic stenosis)
• ECG may show evidence of left ventricular hypertrophy
• CXR may reveal a prominent aorta because of post-stenotic dilation
• Echocardiography helps accurately evaluate aortic valve morphology and estimate the pressure gradient across the LVOT

Left Heart Outflow Obstruction

• In the first week of life, heart failure usually results from left heart obstruction
• If the obstructive lesion is very severe, arterial perfusion may be predominantly by right-to-left blood flow via the arterial duct, so-called duct-dependent systemic circulation
• Closure of the duct under these circumstances rapidly leads to severe acidosis

Duct Dependent Coarctation of the Aorta

• Due to arterial duct tissue encircling the aorta at the duct's insertion point
• Commonly associated with a bicuspid aortic valve (in 70% of patients)
• When the duct closes, the aorta also constricts, causing severe obstruction to the left ventricular outflow
• Presentation: acute circulatory collapse at about two days of age when the duct closes
• Examination: absent femoral pulses, severe metabolic acidosis
• Amenable to surgical repair or balloon dilation

Prenatal Diagnosis of Congenital Heart Defects

• In high-income countries, between 18-20 weeks' gestation, 70% of those infants who require surgery in the first six months of life can be diagnosed antenatally

Symptoms of Congenital Heart Disease

• Depend on the condition
• Although congenital heart disease is present at birth, the symptoms may not appear immediately
• Some problems, such as a small VSD, ASD, or PDA, may never cause any problems
• Murmurs are the most common presentation of minor congenital heart disease
• Symptoms of heart failure: breathlessness, sweating, poor feeding, recurrent chest infections

Ventricular Septal Defects (VSDs)

• Medium VSDs are less likely to close on their own and may require treatment
• Large VSDs allow a lot of blood to flow from the left ventricle to the right ventricle
• Extra blood flow increases blood pressure in the right side of the heart and the lungs
• Symptoms: tachypnoea, tachycardia, pallor, poor feeding, and poor weight gain
• Treatment: closure of the defect (either surgical closure or transcatheter device closure)

Patent Ductus Arteriosus (PDA)

• Persistent patency occurs in 1 in 5000 live births in full-term infants
• Much more common in preterm neonates
• There is a 30-fold higher incidence in patients born at higher altitudes
• PDA is a persistent communication between the descending thoracic aorta and the pulmonary artery
• Murmur: continuous murmur as the pressure in the pulmonary artery is lower than in the aorta throughout the cardiac cycle
• ECG and CXR often are normal
• Echocardiography allows the delineation of the PDA anatomy and the direction and volume of the shunt
• Treatment: intravenous indomethacin or ibuprofen in newborns, closure is recommended to avoid the risk of infective endocarditis in older children

Atrial Septal Defects (ASDs)

• 6-10% of all CHD
• Small ASDs allow only a little blood to leak from one atrium to the other
• Medium and large ASDs allow more blood to leak from one atrium to the other
• Children with isolated ASDs are frequently asymptomatic
• Untreated defect leads to exercise intolerance and atrial arrhythmias in the third or fourth decade of life
• Signs: ejection systolic murmur, pulmonary area
• CXR usually normal in a small ASD
• ECG may be normal in a small lesion but in a larger lesion, there may be right atrial enlargement, right ventricular enlargement, or right axis deviation
• Treatment: either an operation or percutaneous device closure

Tetralogy of Fallot (TOF)

• A combination of four defects
• Most patients with TOF have progressive cyanosis after birth followed by dyspnoea on exertion as a young child
• Faltering growth may be present
• Hypoxic episodes or 'tet spells’ consist of an abrupt onset of rapid shallow breathing, increased agitation, cyanosis, and a decrease in murmur intensity due to reduced blood flow through the RVOT
• Older children with hypoxic spells will squat to increase systemic vascular resistance and thereby reduce hypoxaemia
• Most are diagnosed: antenatally or following the identification of a murmur in the first two months of life
• Cyanosis at this stage may not be apparent, although a few present with severe cyanosis in the first few days of life
• A loud ejection systolic murmur is heard at the left upper sternal border with radiation to both axillae due to the RVOT obstruction
• Treatment: palliative surgery or complete repair

Cardiac Failure

• Failure of the heart to pump sufficient blood, and deliver sufficient oxygen, to satisfy metabolic demands
• Results in under-perfusion which may cause fluid retention and increased blood volume
• Acute and chronic cardiac failure
• Systolic and diastolic cardiac failure
• Right and left ventricular failure
• Causes of left and right ventricular failure
• Coronary heart disease
• Hypertension
• Cardiomyopathies
• Toxins
• Endocrine disorders
• Nutritional deficiencies
• Infiltrative diseases
• Others

Systemic and Pulmonary Hypertension

• Distinguish between pulmonary and systemic hypertension
• B-natriuretic peptide (BNP)
• Causes of systemic hypertension
• End-organ effects of systemic hypertension
• Causes of pulmonary hypertension
• End-organ effects of pulmonary hypertension

Aneurysms and Neoplasms

• Define an aneurysm
• Describe the causes of aneurysms
• Describe the effects of aneurysms
• Define neoplasms
• Describe the causes of neoplasms
• Describe the effects of neoplasms### Causes of Left and Right Ventricular Failure
• Coronary heart disease
• Hypertension
• Cardiomyopathies:
  • Familial/genetic
  • Non-familial/non-genetic (including acquired, e.g. myocarditis)
  • Hypertrophic (HCM)
  • Dilated (DCM)
  • Restrictive (RCM)
  • Arrhythmogenic right ventricular (ARVC)
  • Unclassified
• Drugs:
  • Beta-blockers
  • Calcium antagonists
  • Antiarrhythmics
  • Cytotoxic agents
• Toxins:
  • Alcohol
  • Medication
  • Cocaine
  • Trace elements (mercury, cobalt, arsenic)
• Endocrine:
  • Diabetes mellitus
  • Hypo/hyperthyroidism
  • Cushing syndrome
  • Adrenal insufficiency
  • Excessive growth hormone
  • Phaeochromocytoma
• Nutritional deficiencies:
  • Thiamine
  • Selenium
  • Carnitine
• Obesity and cachexia
• Infiltrative:
  • Sarcoidosis
  • Amyloidosis
  • Haemochromatosis
  • Connective tissue disease
• Others:
  • Chagas' disease
  • HIV infection
  • Peripartum cardiomyopathy
  • End-stage renal failure

Clinical Effects of Left and Right Ventricular Failure

• "Forward" failure:
  • Reduced perfusion of tissues
  • Tends to be more associated with advanced failure
• "Backward" failure:
  • Due to increased venous pressures
  • Dominated by fluid retention and tissue congestion

B-Natriuretic Peptide (BNP)

• Produced by ventricular muscle in response to stress
• Acts on the ANP receptor but with relatively lower affinity and longer half-life than other natriuretic proteins
• Part of a family: ANP (produced in atrial muscle), CNP (from large blood vessels), DNP (present in blood, probably originates from heart)
• Effects:
  • Vessel dilatation
  • Reduced load on heart
  • Changes in glomerular filtration
  • Inhibits renin secretion
  • Decreases aldosterone
  • Natriuresis
  • Reduction in blood pressure

Hypertension

• Definition: Persistent raised blood pressure above 140/90 mmHg
• Classification:
  • Primary vs secondary (based on cause)
  • Essential vs accelerated (based on clinical presentation)
• Epidemiology:
  • Estimated 1.28 billion adults worldwide have hypertension
  • Most (two-thirds) living in low- and middle-income countries
• Impact:
  • Major risk factor for cardiovascular disease
  • Ischaemic heart disease
  • Accelerated atherosclerosis
  • Alzheimer-type dementia
• Importance: Preventable cause of premature disease and death in developed and developing countries

Pulmonary Hypertension

• Definition: Elevated pulmonary artery pressure >25 mmHg at rest
• Causes:
  • Increased pulmonary vascular resistance
  • Diffuse lung disease (e.g. COPD)
  • Elevated left atrial pressure (e.g. left ventricular failure, mitral valve stenosis)
  • Recurrent pulmonary emboli
  • Primary pulmonary hypertension (unknown cause) - genetics
  • Left-right shunts (e.g. ASD, VSD)

End-Organ Effects of Systemic Hypertension

• Brain:
  • Atherosclerosis
  • Ischaemia and TIA
  • Infarct
  • Haemorrhage
• Eyes:
  • Retinal damage
  • Blindness
• Kidneys:
  • Nephrosclerosis
  • Proteinuria
  • Haematuria
  • Chronic renal failure
• Acceleration of atherosclerosis
• Heart:
  • Left ventricular hypertrophy
  • Ischaemic heart disease

Aneurysms

• Definition: Bulging or swollen blood vessel
• Causes:
  • Atherosclerosis
  • Hypertension
  • Berry aneurysm (congenital)
  • Dissecting aneurysm (e.g. Marfan's syndrome)
  • Mycotic aneurysm (infective endocarditis)
• Effects:
  • Local and systemic effects
• Screening, prevention, and treatment

Other Topics

• Transposition of the Great Arteries
• Atrioventricular Septal Defect (AVSD)
• Pulmonary Valve Stenosis
• CHD affecting the valves inside the heart (Atresia, Stenosis, Regurgitation)
• Congenital heart defects (CHD)
• Foetal circulation
• Neonatal circulation - the transition### Congenital Heart Disease (CHD)
• CHD is a problem with the heart's structure that is present at birth
• 0.8% of live births have CHD, making it the most common type of congenital disability

Types of CHD

Non-Cyanotic CHD

• Ventricular Septal Defect (VSD)
• Atrial Septal Defect (ASD)
• Pulmonary Stenosis
• Aortic Stenosis
• Coarctation of the Aorta
• Patent Ductus Arteriosus (PDA)

Cyanotic CHD

• Tetralogy of Fallot (TOF)
• Total Anomalous Pulmonary Venous Return
• Transposition of the Great Arteries
• Tricuspid Atresia
• Truncus Arteriosus
• Hypoplastic Left Heart
• Pulmonary Atresia

Ventricular Septal Defect (VSD)

• 20% of CHD cases
• Defect in the wall between the ventricles
• Small VSDs may close on their own, while medium and large VSDs require treatment
• Signs: Tachypnoea, Tachycardia, Poor weight gain, Heart murmur, Gallop rhythm, Enlarged heart, Hepatomegaly, Cool peripheries

Atrial Septal Defect (ASD)

• 6-10% of CHD cases
• Defect in the wall between the atria
• Small ASDs may close on their own, while medium and large ASDs require treatment
• Signs: Recurrent chest infections, No symptoms, Ejection systolic murmur, Pulmonary area

Patent Ductus Arteriosus (PDA)

• 9-12% of CHD cases
• Failure of the ductus arteriosus to close after birth
• Left-to-right shunt, allowing blood to flow from the aorta to the pulmonary artery
• Signs: Continuous murmur, Poor weight gain, Tachypnoea, Tachycardia

Tetralogy of Fallot (TOF)

• Combination of four defects: Pulmonary valve stenosis, Ventricular Septal Defect, Overriding aorta, Right ventricular hypertrophy
• 4-8% of CHD cases
• Signs: Cyanosis, Dyspnoea on exertion, Faltering growth, Hypoxic episodes ('tet spells')

Transposition of the Great Arteries

• Pulmonary arteries supplied by the left ventricle, and the aorta by the right ventricle
• Cyanosis is always present
• Second heart sound is often loud and single
• No murmur

Atrioventricular Septal Defect (AVSD)

• Holes between the chambers of the right and left sides of the heart
• Valves that control blood flow may not be formed correctly
• Common in babies with Down syndrome
• Signs: Cyanosis at birth or heart failure at 2-3 weeks of life, No murmur heard