Introduction

Ventricular arrhythmias and heart enlargement are two serious heart conditions. These two conditions are interlinked with each other in their outcomes, which are, in a very specific way, related to each other; creating an important resource for both patients and their healthcare providers to initiate positive preventative measures. In this article, the association of enlarged heart size with ventricular arrhythmia and its implications for health are discussed.

What is arrhythmia?

An arrhythmia refers to an abnormal rhythm or beating of the heart.¹ Cardiac arrhythmias are generally defined as situations where the electrical activity of the heart becomes slow, too fast, or even too irregular. Slow heart rhythms or heartbeats can easily be treated by electronic pacemakers. However, rapid heart results in atrial fibrillation or ventricular fibrillation (VF) and chaotic electrical activity within the atria or ventricles which remains one of the leading causes of morbidity and mortality with sudden cardiac death.

What is ventricular arrhythmia?

Ventricular arrhythmias start from your heart's lower chambers, which are also known as the ventricles. Within the ventricles, we find an abnormality of electrical activity due to heart enlargement in this case. These arrhythmias can be very dangerous and often require essential medical care.² It is the primary cause of sudden cardiac deaths.¹

Types of ventricular arrhythmia

There are two subcategories of ventricular arrhythmia as

• Ventricular tachycardia
• Ventricular fibrillation

Ventricular tachycardia

Ventricular tachycardia is further divided into two subcategories as 

• Non-sustained ventricular tachycardia
• Sustained Ventricular Tachycardia

Non-sustained ventricular tachycardia: The rapid ventricular rhythm resolves spontaneously within 30 seconds.

Mechanism: structural abnormality, electrolyte disorder, and metabolic imbalance; drug effects, drugs such as pro-arrhythmic drugs.

Risk factors: It occurs due to Structural or ischemic heart disease.

Signs and symptoms: Asymptomatic(unknown) or palpitations

Management: Implantable cardioverter-defibrillator ICD or medical therapy.

Sustained ventricular tachycardia

These include persistent ventricular tachycardia

Mechanism: Fibrils damage due to ischemic heart disease which allows the electrical impulses to re-enter through these damaged fibrils. 

Some patients do not have structural heart abnormalities. About 10% of the cases are unknown.

Risk factors: structural heart disease and post-myocardial infarction.

Symptoms and signs: Palpitation, hypotension, or syncope.

Management: medicines like Intravenous lidocaine, amiodarone, or procainamide. Catheter ablation is also available.

Ventricular fibrillation

Mechanism: Ischemic heart disease causing re-entry of current leading to disorganised high-frequency excitation.

Risk factors: Patients with Cardiomyopathies can have Ventricular fibrillation due to an increase in end-diastolic pressure, wall tension, or the presence of abnormal channels in ventricular fibres.

Symptoms and Signs: Syncope and death if not treated promptly.

Management: Unsynchronised cardioversion followed by amiodarone.¹

What is heart enlargement?

Heart enlargement is also known as cardiomegaly. Cardiomegaly is defined as the enlargement of the heart, generally seen on imaging screens such as chest X-rays. It usually remains undiagnosed until the symptoms appear.³

Types of heart enlargement

Heart enlargement occurs due to changes in heart muscles, which is called cardiomyopathy. Cardiomyopathy is divided into primary (genetic, mixed, or acquired) and secondary sub-divisions that are related to different types including dilated, hypertrophic, and restrictive cardiomyopathies.

Hypertrophic cardiomyopathy is the most common type of cardiomyopathy causing exertional dyspnea, presyncope, atypical chest pain, heart failure, and sudden cardiac death.

Dilated cardiomyopathy may be genetic or acquired and usually presents with classical symptoms of heart failure with reduced ejection fraction.

Restrictive cardiomyopathy is less common and is usually associated with systemic diseases⁴.

Symptoms

• Cardiomegaly is usually asymptomatic and therefore its diagnosis cannot be confirmed by simply the existence of symptoms alone. The diagnosis can only be relied upon imaging, although the medical history is useful in identification
• symptoms, such as shortness of breath, oedema, fatigue, and chest pain occur
• A physical exam may examine specific findings, such as a displaced point of maximal impulse and murmurs from mitral or tricuspid regurgitation
• Signs such as sinus tachycardia, jugular venous distension, and pulmonary crackles are indicative of decompensated heart failure³

Causes of heart enlargement

Common causes of heart enlargement are as follows:

• Hypertensive heart disease: Chronic high blood pressure causing left ventricular hypertrophy
• Valvular heart diseases: including aortic or mitral regurgitation leading to volume overload
• Hypertrophic cardiomyopathy: This is a common cause of enlarged hearts with unknown mechanisms. A genetic mutation (such as MYBPC3) often contributes to this phenomenon. Hypertrophic cardiomyopathy causes heart enlargement through hypertrophy and proliferation of the cardiac muscles
• Other causes are pulmonary hypertension, myocardial infarction and chronic heart failure⁵

How do ventricular arrhythmia and heart enlargement are related?

Enlargement of the heart, particularly left ventricular hypertrophy (LVH), has been related to a high risk of ventricular arrhythmias (VAs), including ventricular tachyarrhythmia and fibrillation. LVH is due to the thickening of the left ventricle as a result of high arterial pressure or hypertrophic cardiomyopathy that disrupts normal electrical activities of the heart, thereby acting as a substrate for arrhythmias. All these are worsened by inflammation and fibrosis as well as other molecular changes. This association is particularly worrisome for the fact that LVH also increases the risk of sudden cardiac death, especially in combination with arrhythmias.^6,7

Shared complications and risk factors

• An enlarged heart with ventricular arrhythmia can significantly increase the risk of serious cardiovascular complications. Enlargement of the heart may be due to chronic diseases, such as hypertension, or from long-term regular exercise, which interferes with the electrical pathways in the heart, making individuals vulnerable to dangerous arrhythmias that cause life-threatening effects including ventricular fibrillation and sudden cardiac death
• Some studies have shown that structural changes in the heart, like myocardial fibrosis, could be higher risks for those individuals who have a history of intense and long-term exercise, such as athletes. Extreme exercise can cause excessive levels of catecholamines, such chemicals as adrenaline, due to stress that causes constriction of the coronary artery and further stresses the heart's structure and function, increasing the risk of arrhythmias and other cardiac diseases^8,9
• When the left ventricle gets stiffened by thickening, as in LVH due to chronic conditions such as hypertension, genetic syndromes, or other heart disease, which cause heart enlargement, it is unable to pump blood with efficiency as it should, causing heart failure, among other complications like arrhythmias⁹
• Some lifestyle factors that have increased risks for individuals suffering from LVH are uncontrolled hypertension, weight gain, and diabetes^6,9

Diagnosis and monitoring of ventricular arrhythmia and cardiomegaly

Accurate diagnosis is achieved through some approaches:

• Electrocardiogram (ECG): the most common and first-line tool for diagnosing ventricular arrhythmias, it can identify conditions like VT and VF through the examination of electrical activity in the heart.¹⁰ It gives a high-resolution structure and function so that ventricular size and wall thickness would be potentially measurable with a great degree of accuracy
• Holter Monitoring: It is portable; for 24 to 48 hours, it monitors the heart's ECG rhythm and tries to diagnose intermittent arrhythmias¹⁰
• Electrophysiological Studies (EPS): An invasive procedure in which catheters are placed inside the heart to activate its electrical activity and to localise the position where arrhythmia originates¹¹
• Imaging Techniques: A chest X-ray is a commonly used, first-line method of discovering enlargement of the heart. It gives a rapid, non-invasive view of the size, shape​ and function of the heart^11,12
• Cardiac MRI and CT imaging techniques, for more complex cases, provide high-resolution detailed images of heart chambers to identify some structural abnormalities that cause cardiomegaly¹²

Monitoring

There are a range of tools applied for continuous monitoring as follows:

• Implantable Cardioverter Defibrillator (ICD): It continuously monitors the patient's heart rhythm and can deliver electrical shocks to reverse the normal rhythm if life-threatening arrhythmias occur¹⁰
  • Wearable ECG Devices allow for monitoring through a remote, and real-time data are provided to healthcare professionals to monitor episodes of arrhythmia¹¹
• Echocardiographic Follow-up: Serial echocardiography helps in serial monitoring of changes over time with cardiomegaly and its functional deterioration¹¹
• Biomarkers: Blood tests, such as B-type natriuretic peptide (BNP), determine the level of heart failure and thus provide help in treatment-making decisions​¹²
• Chest X-ray: repeated chest X-rays may be followed over time to identify changes in cardiac size and detect deterioration in cardiomegaly¹²
• Emerging Technologies
  • AI and Machine Learning: Nowadays advances in artificial intelligence, including those used in medical imaging, improve the detection and monitoring of both arrhythmias and cardiomegaly more sensitively and with greater accuracy than conventional methods​¹²

Treatment and management approaches

Medications

Medications are the basics of treatment both for ventricular arrhythmia and heart enlargement. Some of the common medications include:

• Beta-blockers and ACE inhibitors regulate the blood pressure and heart rate, thereby reducing the workload on the heart. Beta-blockers also control or stop arrhythmias and so enlarge the heart
• Antiarrhythmic drugs like amiodarone are always recommended to prevent recurrent arrhythmias but are often associated with side effects and used in high-risk patients¹³

Device-based interventions

In high-risk cases, implantable devices are valuable preventive tools:

• Implantable Cardioverter-Defibrillators (ICDs) continuously monitor the heartbeat and give corrective shocks to the heart when necessary to prevent sudden cardiac attack, especially among patients who have already experienced life-threatening arrhythmias
• Cardiac Resynchronisation Therapy devices enhance the pumping ability in patients where heart enlargement has resulted in symptoms of heart failure; thereby overall heart function improved¹⁴
• Catheter ablation is less invasive and is used for patients who have recurrent arrhythmias and also do not respond well to medications. It causes the removal of abnormal tissues which contribute to arrhythmias to prevent further complications¹⁵

Lifestyle modifications

Lifestyle interventions support medical therapies to achieve an optimal outcome:

Healthy diet, regular physical activity, smoking cessation, and avoiding alcohol intake. These changes are important to prevent risk factors which may worsen ventricular arrhythmia and are further causing enlargement of the heart.^13,14

Preventive measures

Preventive measures for ventricular arrhythmia and heart enlargement emphasise lifestyle changes, medications, and advanced medical devices based on the risk factors of patients.

Lifestyle Modifications: Avoid smoking and alcohol, follow a healthy diet, and maintain regular exercise. Monitoring blood pressure and cholesterol levels is also necessary, as both can affect heart size and rhythm stability.¹³

Medical devices like implantable cardioverter-defibrillators (ICDs) can prevent sudden heart attacks by monitoring and correcting abnormal rhythms. Catheter ablation, a procedure to prevent abnormal electrical pathways in the heart, is an option for patients who do not respond to medication​.¹⁶

Conclusion

Ventricular arrhythmia is one of the major causes of morbidity and mortality in patients with cardiomegaly (heart enlargement). In order to enhance their outcome and possibly prevent mortality-related cardiac events, such patients need early detection, appropriate management, and addressing the underlying causes.