30  Miscellaneous Cardiac Conditions

30.1 Introduction

Beyond the commonly discussed congenital and acquired heart diseases such as septal defects, ductal anomalies, coarctation, and rheumatic disease, children may present with a variety of other cardiac conditions that, although less frequent, are clinically significant. These disorders encompass abnormalities of rhythm, cardiomyopathies, pericardial disease, pulmonary hypertension, and conditions secondary to systemic illness.

In the Ghanaian context, where diagnostic resources are limited and late presentations are common, awareness of these miscellaneous cardiac conditions is vital for timely recognition, appropriate referral, and improved outcomes. This chapter explores these diverse entities, emphasising their pathophysiology, clinical features, diagnostic approach, and management principles.

30.2 Arrhythmias in Children

30.2.1 Overview

Arrhythmias refer to disturbances in the heart’s rhythm, either too slow, too fast, or irregular. They can occur in structurally normal hearts or as complications of congenital heart disease, myocarditis, or postoperative states.

30.2.2 Common Types

• Sinus bradycardia: Often physiological in athletes or during sleep, but may occur with raised intracranial pressure or hypothyroidism.
• Sinus tachycardia: Commonly secondary to fever, anaemia, or dehydration.
• Supraventricular tachycardia (SVT): The most common pathological tachyarrhythmia in children, often due to re-entry mechanisms.
• Ventricular tachycardia (VT): Rare but life-threatening, seen in myocarditis or cardiomyopathy.
• Heart block: May be congenital or secondary to maternal lupus, cardiac surgery, or myocarditis.

30.2.3 Clinical Features

• Palpitations, dizziness, syncope, or chest discomfort
• Cyanosis or heart failure in sustained tachyarrhythmia
• Irregular pulse or variable heart rate on auscultation

30.2.4 Diagnosis and Management

Diagnosis is made via ECG, Holter monitoring, or event recorders.
Management includes:

• Vagal manoeuvres and adenosine for SVT
• Amiodarone or procainamide for VT
• Pacemaker insertion for complete heart block
• Long-term follow-up with paediatric cardiology is essential.

30.3 Myocarditis

30.3.1 Definition and Aetiology

Myocarditis is inflammation of the myocardium that impairs contractility. It may be viral, bacterial, autoimmune, or toxin-induced.

Common causes include:

• Viral: Coxsackie B, adenovirus, enterovirus, parvovirus B19
• Bacterial: Diphtheria, Staphylococcus, Mycoplasma
• Others: Kawasaki disease, autoimmune disorders, drug reactions

30.3.2 Pathophysiology

Infectious agents cause direct myocyte injury or immune-mediated destruction, leading to myocardial oedema, necrosis, and fibrosis. This results in reduced systolic function and may progress to dilated cardiomyopathy.

30.3.3 Clinical Features

• Fatigue, feeding difficulties, dyspnoea
• Tachycardia disproportionate to fever
• Gallop rhythm, hepatomegaly, or heart failure signs
• In severe cases, cardiogenic shock

30.3.4 Diagnosis

• Elevated cardiac enzymes (CK-MB, troponin)
• ECG: ST-T changes, arrhythmias
• Echocardiogram: Global hypokinesia, chamber dilation, reduced ejection fraction
• Viral studies where available

30.3.5 Management

• Supportive: oxygen, diuretics, inotropes
• Avoid excessive fluid loading.
• IV immunoglobulin (IVIG) or steroids may be considered in selected cases.
• Long-term follow-up for ventricular function recovery

30.4 Cardiomyopathies

Cardiomyopathies are diseases of the heart muscle not explained by abnormal loading or coronary artery disease. They are classified based on ventricular morphology and function.

30.4.1 Dilated Cardiomyopathy (DCM)

• Most common in children; can follow viral myocarditis, genetic mutations, or nutritional deficiencies (e.g., selenium deficiency).
• Pathophysiology: Progressive ventricular dilation and systolic dysfunction.
• Clinical features: Fatigue, failure to thrive, dyspnoea, hepatomegaly, and heart failure.
• Management: Standard heart failure therapy: ACE inhibitors, beta-blockers, diuretics, and occasionally anticoagulation.
• Prognosis: Variable; some recover, others progress to chronic failure or require transplantation.

30.4.2 Hypertrophic Cardiomyopathy (HCM)

• A genetic disorder characterized by asymmetric septal hypertrophy and diastolic dysfunction.
• May present with: Syncope, exertional dyspnoea, or sudden cardiac death, particularly during exercise.
• Diagnosis: ECG showing LV hypertrophy; echocardiography reveals a thickened septum and a small LV cavity.
• Management: Beta-blockers or calcium channel blockers; avoid dehydration and strenuous activity.

30.4.3 Restrictive Cardiomyopathy (RCM)

• Characterized by impaired ventricular filling with normal systolic function.
• Rare in children, sometimes secondary to infiltrative diseases.
• Features: Hepatomegaly, ascites, elevated jugular venous pressure.
• Management: Diuretics for congestion; poor prognosis without transplant.

30.5 Pericardial Diseases

30.5.1 Pericarditis

Inflammation of the pericardium often secondary to viral infection, rheumatologic disease, or post-surgical states.

Clinical features:

• Sharp chest pain relieved by sitting forward
• Pericardial rub on auscultation
• Low-grade fever

Diagnosis: ECG showing diffuse ST elevation; echocardiogram may reveal effusion.
Management: NSAIDs, rest, and treatment of underlying infection.

30.5.2 Pericardial Effusion and Cardiac Tamponade

Fluid accumulation within the pericardial sac impedes cardiac filling, leading to tamponade.
Causes: Tuberculosis (common in Ghana), malignancy, uremia, trauma.
Clinical features: Dyspnoea, tachycardia, muffled heart sounds, distended neck veins, pulsus paradoxus.
Management: Pericardiocentesis (urgent in tamponade), antituberculous therapy if indicated.

30.6 Pulmonary Hypertension (PH)

30.6.1 Definition and Classification

Pulmonary hypertension is a sustained elevation of pulmonary artery pressure >25 mmHg at rest. It may be:

• Primary (idiopathic): rare in children
• Secondary: Due to chronic hypoxia, congenital heart disease, or pulmonary disorders

30.6.2 Pathophysiology

Chronic elevation of pulmonary vascular resistance leads to right ventricular hypertrophy and eventual right heart failure.

30.6.3 Clinical Features

• Exertional dyspnoea, fatigue, syncope
• Loud pulmonary component of the second heart sound
• Right ventricular heave and signs of failure

30.6.4 Diagnosis

• Echocardiography: Estimates pulmonary pressures
• Cardiac catheterization: Gold standard
• CXR: Enlarged pulmonary arteries
• ECG: Right axis deviation, RV hypertrophy

30.6.5 Management

• Treat underlying cause (e.g., repair of shunt lesions)
• Oxygen therapy for hypoxia
• Vasodilators: Sildenafil, calcium channel blockers
• Anticoagulation in selected patients
• Avoid dehydration and high altitude exposure

Prognosis depends on the cause and reversibility of vascular changes.

30.7 Kawasaki Disease

An acute, self-limiting vasculitis of childhood, predominantly affecting the coronary arteries. Most common in children under 5 years.

30.7.1 Clinical Features

• Persistent high fever >5 days
• Conjunctival injection, strawberry tongue, cracked lips
• Rash, cervical lymphadenopathy
• Desquamation of fingers and toes
• Coronary artery aneurysms may develop in untreated cases.

30.7.2 Diagnosis and Management

Clinical diagnosis: Elevated ESR, CRP, and platelets support inflammation.
Echocardiogram to detect coronary aneurysms.

Treatment includes:

• IVIG (2 g/kg single dose) within 10 days of onset
• High-dose aspirin during acute phase, then low-dose for 6–8 weeks
• Long-term cardiology follow-up for aneurysm surveillance

30.8 Cardiac Tumours

30.8.1 Types

• Rhabdomyoma: Most common; often associated with tuberous sclerosis
• Fibroma, Teratoma, Myxoma, Hemangioma: Less common

30.8.2 Clinical Manifestations

• Obstructive symptoms (outflow tract obstruction)
• Arrhythmias
• Heart failure or sudden death

Diagnosis: Echocardiography reveals intracardiac mass; MRI provides further characterization.
Management: Rhabdomyomas often regress; others may require surgical excision.

30.9 Systemic Diseases with Cardiac Involvement

Certain systemic illnesses have important cardiac manifestations.

30.9.1 Anaemia and Malnutrition

Chronic anaemia leads to high-output cardiac failure, while severe malnutrition can cause cardiac atrophy and reduced contractility.

30.9.2 Sickle Cell Disease

Recurrent anaemia, iron overload, and pulmonary hypertension contribute to cardiomegaly and diastolic dysfunction.

30.9.3 Sepsis

Severe sepsis may cause myocardial depression secondary to cytokine release, which is reversible with recovery.

30.9.4 Thyroid Disorders

• Hyperthyroidism: Tachyarrhythmias and high-output failure
• Hypothyroidism: Bradycardia and pericardial effusion

30.9.5 HIV-Associated Cardiac Disease

In resource-limited settings like Ghana, HIV-infected children may develop:

• Dilated cardiomyopathy
• Pericardial effusion (often tuberculous)
• Pulmonary hypertension
• Drug-related cardiotoxicity

Early ART initiation and cardiac monitoring are essential to reduce morbidity.

30.10 Drug-Induced Cardiotoxicity

Several medications used in paediatrics can cause cardiac dysfunction.

Examples:

• Anthracyclines (e.g., doxorubicin): Dose-dependent cardiomyopathy
• Cyclophosphamide: Myocardial necrosis
• Antimalarials (chloroquine): QT prolongation

Prevention: Regular ECG, echocardiography, and adherence to cumulative dose limits.

30.11 Prognosis and Long-Term Care

The outcome of miscellaneous paediatric cardiac conditions varies widely. Transient viral myocarditis may resolve completely, while genetic cardiomyopathies often progress despite optimal therapy. Chronic conditions such as pulmonary hypertension and postoperative arrhythmias require ongoing multidisciplinary follow-up.

Early detection through echocardiography, routine screening in high-risk children, and integration of paediatric cardiology into tertiary care systems in Ghana are crucial to improving survival and quality of life.

30.12 Conclusion

Miscellaneous paediatric cardiac conditions represent a heterogeneous group that collectively contribute significantly to cardiac morbidity in children. While individually less frequent than septal defects or rheumatic disease, they often carry substantial diagnostic and therapeutic challenges. For medical students and practitioners in Ghana, a high index of suspicion, thorough clinical evaluation, and appropriate use of echocardiography can facilitate early recognition and management. Strengthening diagnostic infrastructure and ensuring access to paediatric cardiology services remain essential priorities in improving outcomes for these children.