What is Double-Chambered Right Ventricle?
A Double-chambered right ventricle (DCRV) is a type of birth defect of the heart. In this condition, the right chamber of the heart is divided into two sections. One part is under high pressure while the other is under low pressure. However, some people develop this condition after they are born, due to an increase in size of certain muscle structures in the right chamber of the heart. This usually happens to those who have small, restricted holes in the wall between the lower chambers of the heart.
There are two main types of DCRV, categorized by what tissue is causing the division in the heart chamber. For type 1 DCRV, there are unusual muscle bundles crossing the right chamber of the heart. In type 2 DCRV, certain muscles on the wall and the divider of the heart enlarge, causing the division.
The most common issue seen with DCRV is a defect in the wall separating the lower chambers of the heart (found in up to 75% of DCRV patients). Yet, DCRV can also occur alongside other heart conditions, like tetralogy of Fallot, double outlet right ventricle, Ebstein anomaly, transposition of the great arteries, a ruptured sinus of Valsalva aneurysm, hole in the wall separating the upper heart chambers, a quadricuspid aortic valve, a persistent left superior vena cava, and a narrowing of the pulmonary valve.
What Causes Double-Chambered Right Ventricle?
What causes muscle bundles to grow large and obstructive is still a mystery. Some possible explanations include:
1. They could be a response to faster blood flow due to a hole in the ventricular septum (wall separating the heart’s chambers). This might cause the supraventricular crest, a part of the heart muscle, to enlarge and become obstructive.
2. The septomarginal trabecula or the moderator band, structures located in the heart, may be displaced upwards and grow progressively larger over time.
3. A muscular shelf might extend from the septoparietal trabeculations to the right ventricular apex (from one part of the heart muscle to another). Along with other factors, this could result in the formation of obstructive muscle bundles.
Risk Factors and Frequency for Double-Chambered Right Ventricle
Double chambered right ventricle (DCRV) is found in between 0.5% and 2% of patients with congenital heart disease. This condition hasn’t been linked to any specific genetic pattern. It seems to be more prevalent in male infants than female ones, with a ratio of 2:1.
- DCRV could appear in up to 10% of children after they’ve had a ventricular septal defect corrected.
- It’s found in 3.1% of patients who have had repair of their tetralogy of Fallot.
- DCRV can also be found in adults, in 2.1% of cases.
These are often classified as “de novo” cases of DCRV, meaning that they are new, not inherited, cases.
Signs and Symptoms of Double-Chambered Right Ventricle
Double-chambered right ventricle (DCRV) is typically diagnosed in children. When the right ventricle has mild-to-moderate blockage, it can cause no symptoms (asymptomatic) and imitate pulmonary valve stenosis — this is a heart condition that affects the flow of blood from the heart to the lungs. The patients are usually noticed by a cardiologist due to a harsh holosystolic murmur accompanied by thrill, a vibrating sensation, which can be best heard along the left side of the breastbone. Cyanosis, a physical finding where the skin, lips, and nails appear blue due to low oxygen levels, is another common symptom if the patient has an atrial septal defect. This is a hole in the wall between the two upper chambers of the heart which allows the blood to pass from the right atrium to the left leading to an inadequate oxygen supply to the body.
In adult DCRV patients, shortness of breath and fatigue, especially during physical activity, are the most common symptoms. This is due to the right ventricle’s struggle to increase its output during exercise. If the blockage in the right ventricle is severe, the patient might also experience dizziness, discomfort in the chest, an irregular heartbeat, and fainting. In rare cases, patients with more severe obstruction may experience sudden death during strenuous exercise. This can occur as a result of right heart failure leading to an inadequate blood supply to the heart which in turn causes a decrease in oxygen supply (ischemia) and triggers irregular heartbeats that could lead to sudden death.
Testing for Double-Chambered Right Ventricle
An electrocardiogram, also known as an ECG, is often used to detect a medical condition characterized by enlargement and thickening of the right side of the heart (right ventricular hypertrophy), and deviation of the normal electrical axis of the heart towards the right (right axis deviation). An ECG might also reveal a specific pattern of electrical conduction delay known as a right bundle branch block. Even if no enlargement of the right ventricle is spotted on the ECG, some patients might present the appearance of upright T waves in V3R, which can be indicative of abnormalities.
Another diagnostic technique called transthoracic echocardiography is typically the primary method to detect a double-chambered right ventricle (DCRV) and measure pressure differences within the heart, particularly in children. This technique can visualize the movement of blood — during the contraction phase of the heart cycle, the space around muscle bundles decreases which enlarges any obstruction to the flow. This situation is commonly quantified with the help of echocardiography and can be visualized using color Doppler with either transthoracic or transesophageal echocardiography. These techniques involve the use of sound waves to measure and monitor the flow obstruction over time.
In situations where the use of transthoracic echocardiography is restricted due to the body size or the presence of other congenital heart defects, especially in adults, other imaging techniques like transesophageal echocardiography, cardiac magnetic resonance imaging, or cardiac computed tomography can provide crucial insights.
Cardiac magnetic resonance imaging (CMR) offers a non-invasive, radiation-free means to supplement transthoracic or transesophageal echocardiography. This option is particularly helpful for adults where non-invasive cardiac imaging can be challenging due to body size. CMR is also handy when a DCRV is overlooked due to additional heart lesions as it can confirm any related cardiac anomalies and assess the pressure gradient and wall thickness of the right ventricle.
For people who can’t have a CMR due to claustrophobia, implants, or specific types of pacemakers and defibrillators, a cardiac computed tomography (CT) scan can also effectively diagnose DCRV.
In the past, DCRV diagnosis was primarily made by cardiac catheterization, a procedure where a thin tube is inserted into a blood vessel leading to the heart. Here, data would show contrasting pressure levels in the pulmonary artery and the sub-infundibular chamber versus the right ventricular apex. The use of angiography, which involves the use of X-rays to visualize blood flow, would complete the diagnosis of this malformation.
Treatment Options for Double-Chambered Right Ventricle
Current guidelines suggest considering surgery to close the hole in the heart wall (ventricular septal defect) and remove the thickened muscle bundles in patients who have significant blockage in the right ventricle of the heart and show signs of heart failure, have limitations doing exercise, or have a bluish color of the skin due to low oxygen (cyanosis). The guidelines also encourage considering surgery in patients without symptoms but who have severe blockage in the right ventricle, with a pressure difference of more than 40 mmHg across the compartments inside the right heart chamber.
Treatment decisions can be more complex for patients without symptoms due to the large discrepancy between the blockage levels in the right ventricle, as measured by echocardiography and invasive procedures. Echocardiography tends to overestimate this parameter, which is especially important as it has largely replaced cardiac catheterization in diagnosing and assessing most heart defects from birth. Therefore, some professionals recommend surgery to close the ventricular septal defect and remove the muscle bundle because of the progressive nature of blockage in the right ventricle in a particular type of heart defect often referred to as DCRV.
Beta-blockers, a type of medicine that slows the heart rate down, have been reported to improve symptoms and exercise capability in DCRV patients with dynamic obstruction in the right ventricle. Therefore, these can be useful before surgery. Some patients with DCRV may also undergo rapid heartbeats from the ventricles, and these patients can benefit from other medications to slow the heart rate or a procedure to destroy the area of the heart causing the rapid heart rate. Some doctors recommend a device called a cardioverter-defibrillator that can correct an abnormal heart rhythm, for patients with rapid heartbeats before or after surgery or those not willing to have surgical removal of the anomalous muscle bundles.
What else can Double-Chambered Right Ventricle be?
There are certain conditions that can make it difficult to identify a double-chambered right ventricle (DCRV). These include illnesses where the right side of the heart is unusually thickened. Below are some of these conditions:
- Tetralogy of Fallot (a combination of four heart defects)
- Pulmonic valve stenosis (a condition where the heart’s pulmonic valve is narrow)
- Isolated ventricular septal defect (a hole in the wall that separates the heart’s lower chambers)
- Pulmonary valve stenosis with ventricular septal defect (a narrow pulmonary valve and a hole in the ventricular wall)
- Idiopathic hypertrophic obstructive cardiomyopathy on the right side (an unexplained increase in heart muscle thickness that can obstruct blood flow)
These ailments can complicate the identification of a DCRV, an abnormality where the right side of the heart is divided into two sections.
What to expect with Double-Chambered Right Ventricle
Children who have surgery to treat DCRV are typically expected to have positive long-term results and typically do not need additional surgery due to recurring obstructions in the heart’s chambers. Adults with DCRV who choose not to have surgery also tend to have a low level of long-term health issues, even with high pressure differences within the ventricles of their hearts.
However, as this condition can worsen over time and the outcomes after the operation are generally good with only potential mild side effects, such as minor leakage in the tricuspid valve, some experts recommend surgery to close the hole in the ventricular septum and remove the enlarged muscle bundle, even in patients who don’t show symptoms.
Possible Complications When Diagnosed with Double-Chambered Right Ventricle
While it’s not very common, complications can happen after heart surgery. These might include risk of death from low heart performance or heart failure, even if the surgery was successful. Some patients may experience heartbeat problems or right-sided heart dysfunction.
A particular complication that can present after repairing Tetralogy of Fallot in infants, referred to as DCRV, can appear in around 3.1% cases. This issue develops when certain muscle bundles in the heart increase in size or become fibrous. If you hear a loud heartbeat noise during a check-up, this might mean that the muscle bundles have become reobstructed – that there’s another blockage or narrowing happening. This generally happens due to growing or fibre-developed muscle bundles, and the patient might need another operation. Because of this, it’s strongly advised that these patients are monitored continuously.
There’s also a risk that other heart defects, specifically holes in the heart wall between the left and the high-pressure part of the right side of the heart, might not be spotted during corrective surgery. This can happen because larger muscle bundles can obscure small defects on basic exams. Additionally, if there’s not a big pressure difference between the left and right sides of the heart, it might not show up on pre-operation heart scans or echo tests. After surgery, if the right side of the heart pressure drops, it may become noticeable. If the defect is small, additional surgery is likely not necessary.
In general, regular monitoring of heart function and symptoms is key for recovery and prevention of complications.
Preventing Double-Chambered Right Ventricle
If feasible, it’s crucial to have a conversation about early treatment after a diagnosis with patients and their parents. This can help prevent the worsening of a condition affecting the right side of the heart, caused by abnormal muscle bundles, which typically deteriorates over time. Both patients and their parents should understand that surgical outcomes are generally positive.
If surgery is not an option, regular check-ups with a cardiologist are necessary. This helps lessen the likelihood of complications such as reduced heart function, decreased blood supply to the heart, irregular heartbeat, and potential sudden heart-related death.
