Overview

Heart conditions can be complex and due to various factors. They range from mild and harmless symptoms to critical ones like heart attacks and strokes. In this article, we will tackle cardiomegaly (enlarged heart) and one of its leading causes of pulmonary (lung) oedema.

To start off, we will have a brief overview on pulmonary oedema and cardiomegaly – so what is pulmonary oedema? It is characterised by the unusual accumulation of fluids in the lungs, and it has 2 forms: cardiogenic and noncardiogenic.¹ Once there is fluid accumulation, this can cause the lungs to be strained and result in difficulty breathing.¹ If left untreated, it can be life-threatening and lead to extreme hypoxia.²

Now, what is cardiomegaly? This term is an umbrella term for multiple heart conditions that deal with its enlargement - the term itself means heart enlargement.³ This enlargement has two forms: dilated and hypertrophic – dilatation refers to when the heart walls stretch out and become thin/weak which enlarges the heart and puts it at a risk of heart failure.⁴ Meanwhile hypertrophy refers to the thickening of the heart walls which makes the heart get tired faster by requiring more leading to inefficient pumping.⁴ Hypertrophy can stem from high blood pressure.⁴

Hence, in this article we will tackle pulmonary oedema and how it is linked to cardiomegaly. So let us dive in.

Pulmonary oedema

Overview 

As mentioned above, pulmonary oedema refers to the fluid build up in the lungs, more specifically inside of the air sacs, known as the alveoli.⁵ When the lungs get filled with fluid instead of air, it can cause distress and difficulty in breathing for the patient. It is mostly due to heart conditions, but it can be derived from kidney failure, going to high altitudes or blood transfusions.⁶ Once this happens, the lungs will not be able to deliver the proper amount of oxygen to the rest of the body which can lead to hypoxia and can lead to life-threatening scenarios.⁶ However, fortunately pulmonary oedema is reversible and can be treated.⁶

Most patients that experience this fluid build-up are older patients. round 80% of people who have heart failure experience pulmonary oedema, with it being more common in men (assigned at birth) than women (assigned at birth).⁶

Causes

There are multiple origins for pulmonary oedema and they include:^2,5,6

Cardiogenic pulmonary oedema (CPO)

• Left cardiac dysfunction, also known as left sided heart failure. This is the most common cause for CPO, and it is when the left ventricle of the heart fails to effectively pump blood. In turn, this leads to increased pressure in the pulmonary veins. This then leads to fluid leaking into the lungs and causing oedema
• High blood pressure or hypertension can overload the heart with time and eventually lead to heart failure as well as oedema
• Valve disorders in the heart like aortic stenosis can lead to increased pressure in the heart and lungs, and consequently leading to CPO

Non-cardiogenic pulmonary oedema (NCPO)

• Pulmonary oedema can also rise due to causes that are independent of heart issues. These causes such as infections like pneumonia can result in injury to the lungs, or even kidney failure
• Being at higher altitudes than usual or taking certain medications can increase the risk of NCPO
• Acute respiratory distress syndrome (ARDS) is referred to as an inflammation in the lungs with severe hypoxia. ARDS can be direct (e.g. pneumonia) or indirect (e.g. sepsis, multiple blood transfusions)

Symptoms

There are several symptoms associated with pulmonary oedema such as:⁶

• Shortness of breath, specially when lying down
• Wheezing and shallow breathing
• Sensation of suffocation
• Coughing out sputum that is pinkish (blood) and frothy
• Cyanosis which is the blue coloration of the skin and lips indicating low oxygen levels
• Sweating
• Swelling in the feet
• Anxiety from breathing issues

Cardiomegaly

Overview

Cardiomegaly in simple terms means enlargement of the heart. However to be more accurate, it refers to when the transverse diameter of the cardiac silhouette is more than half of the transverse diameter of the chest on a CT scan.³ Cardiomegaly is usually an outcome from a different illness than an illness on its own.³ As mentioned above, cardiomegaly can be dilated or hypertrophic.

Causes

Cardiomegaly can have multiple origins such as:³

• Coronary artery disease including infarction and ischemia which is the common cause
• High blood pressure
• Heart valve disease like
  • stenosis
  • regurgitation of the valves
  • bacterial endocarditis
• Congenital heart diseases and disorders which affect the structure of the heart and cause the enlargement over time. Examples include
  • atrial septal defect
  • Ebstein anomaly 
• Toxin-induced cardiomyopathy from the use of drugs like
  • Cocaine 
  • lcohol
• Autoimmune origins such as collagen vascular disease
• Arrhythmia is characterised by irregular heart rhythms. It can lead to the heart increasing its workload and as a result leading to enlargement

How is pulmonary oedema related to cardiomegaly?

As discussed in the sections above, the health of the heart and lungs is closely connected. Cardiogenic pulmonary oedema (CPO) and heart failure can increase pressure within the lungs, causing fluid to accumulate and resulting in oedema. 

Conversely, damage to the lungs can raise pulmonary pressure and place additional strain on the heart, potentially leading to cardiomegaly. This creates a vicious cycle in which the heart and lungs continue to negatively affect each other’s function.

Diagnosis

Diagnosis of pulmonary oedema can be done through multiple ways:^5,6

• Checking for signs and symptoms as well as a medical history for any root causes that can be relevant
• Physical examination e.g.
  •  checking the lung and heart sounds
• Performing a chest x-ray to see the fluid accumulation in the lungs or enlargement of the heart
• Electrocardiogram, which is used to assess any abnormal heart rhythms or ischemia
• Echocardiogram to check for the size of the heart and the presence of any lesions or ruptures
• Blood tests such as BNP (brain natriuretic peptide) levels, which can be used to assess if the oedema is due to a cardiac origin
• Tests to assess the lung function like
  • oxygen exchange efficiency

Treatment

Pulmonary oedema

Treatment of pulmonary oedema can be done through:^5,6

• General management such as addressing the root cause of the oedema (if its cardiogenic or not)
• Use of medication like
  • diuretics to remove excess fluid buildup in the body and ease the pressure on the lungs, 
  • Nitroglycerin to lower heart pressure 
  • ACE inhibitors to manage blood pressure levels
• Oxygen supplementation through nasal cannula
• Ventilators
• Renal replacement therapy in case of kidney failure from pulmonary oedema

Cardiomegaly

Treating and managing cardiomegaly is done through:³

• Lifestyle changes such as
  • quitting smoking, 
  • exercise, 
  • loss of excess weight, 
  • lowering alcohol intake, and 
  • having a healthy diet
• Using medications like ACE inhibitors or ARB (if there is intolerance to ACE) as a treatment for asymptomatic patients who have a history of heart infarction
• Using diuretics to lower the fluid in the body and as a result easy the pressure on the heart and consequently the lungs
• In more advanced cases, surgery can be an option; this includes transplants, using devices like pacemakers or valve repair

Prognosis

Pulmonary oedema

Pulmonary oedema can be life-threatening and requires immediate treatment to avoid complications and mortality. While quick and adequate treatment is capable of reversing oedema, around 20% of patients with this illness end up dying.⁶ However, patients who do recover go back to their normal lives within 6-12 months.⁶

Cardiomegaly

People who have symptoms of heart failure have high mortality regardless of advancement of healthcare.³ Hence, it is important to have regular checkups and tests to monitor one’s health. Additionally, the stage, age and risk factors involved all play a role in the prognosis of the patient e.g. the higher the age the higher the risk of mortality.³ It is estimated that a five-year mortality is about half of cases, and 1 year mortality is 30%.³

Summary

Pulmonary oedema is a serious condition that can be life threatening if left unattended. It is characterised by the fluid build up in the lungs that ends up pressuring their ability to work, thereby leading to hypoxia and other consequences. 

Pulmonary oedema can lead to enlargement of the heart by straining the cardiac muscle to function harder, and vice versa the heart muscle can lead to increased pressure in the lungs and injury. Hence, these two illnesses go hand in hand together and it is crucial to understand the causes (aetiology) of each to give the appropriate treatment and provide the best prognosis possible for the patient.