Double Inlet Left Ventricle: Symptoms, Types, Causes and Treatment

Double Inlet Left Ventricle (DILV) is a rare, complex congenital heart defect that fundamentally alters normal blood flow through the heart. It presents significant challenges for patients and clinicians alike, from early diagnosis to lifelong management. In this article, we will explore the key symptoms, anatomical types, underlying causes, and modern treatment approaches for DILV—synthesizing current research and clinical experience to provide a comprehensive understanding of this condition.

Symptoms of Double Inlet Left Ventricle

Living with DILV can affect individuals very differently, depending on the specific anatomy and associated complications. Symptoms often appear early in life, but severity and progression can vary. Recognizing the pattern of symptoms is crucial for timely diagnosis and management.

Symptom	Presentation	Timing	Source
Cyanosis	Bluish skin/lips	Neonatal/Infancy	3
Heart Failure	Poor feeding, fatigue	Infancy	3
Murmur	Abnormal heart sounds	At diagnosis	1 3
Arrhythmia	Irregular heartbeat	Childhood/Adult	10 11

Table 1: Key Symptoms

Cyanosis: The Most Recognizable Sign

Cyanosis—a bluish tint to the skin, lips, or nail beds—is often the first visible sign, especially in newborns. This occurs when oxygen-poor (deoxygenated) blood is circulated throughout the body due to the abnormal mixing inside the heart. Cyanosis tends to be more pronounced if there is pulmonary stenosis or obstruction to blood flow to the lungs, limiting oxygen uptake 3.

Signs of Heart Failure

When pulmonary stenosis is absent, excessive blood may flow to the lungs, causing symptoms of congestive heart failure. In infants, this can manifest as poor feeding, rapid breathing, excessive sweating (especially while feeding), and failure to thrive. Timely recognition is essential to initiate medical management and prevent complications 3.

Murmurs and Arrhythmias

A heart murmur—an extra or unusual sound heard during a heartbeat—is commonly detected during a physical exam. It often reflects turbulent blood flow through abnormal valves or septal defects 1 3. As individuals age, they may also develop arrhythmias (irregular heart rhythms), particularly after surgical interventions or as a late complication 10 11.

Variable Presentation

The severity and combination of symptoms depend heavily on the specific cardiac anatomy:

• Degree of pulmonary or systemic outflow obstruction
• Presence and size of ventricular septal defects
• Type and function of atrioventricular valves

Some children may remain relatively asymptomatic during early childhood, while others require immediate intervention after birth 13.

Types of Double Inlet Left Ventricle

DILV is not a single, uniform defect—rather, it encompasses a spectrum of anatomical variations. Understanding these types is vital for tailoring management and anticipating potential complications.

Type	Key Feature	Prevalence/Notes	Source
Holmes Heart	VA concordance, rudimentary RV	Rare	2 7
With TGA	Transposed great arteries	Most common	1 6 7
Valve Morphology	2 AV valves or common AV valve	Variable	1 5
Ventricular Inversion	Inverted ventricles (l-loop)	~63% in studies	1 3 6

Table 2: Anatomical Types of DILV

Holmes Heart (VA Concordance)

The "Holmes heart" is a classic form where both atria connect to a dominant left ventricle, with a rudimentary right ventricle present. The great arteries are normally related (ventriculoarterial concordance), which is quite rare compared to other forms 2 7.

DILV with Transposed Great Arteries (TGA)

The most common type of DILV involves transposition of the great arteries (TGA)—where the aorta and pulmonary artery arise from the wrong ventricles. This anatomical arrangement affects blood flow and often necessitates complex surgical planning 1 6 7.

Atrioventricular Valve Variations

• Two AV valves: Both the mitral and tricuspid valves are present, though their morphology and function may vary 1 5.
• Common AV valve: Some hearts have a single, shared valve between the atria and the ventricle 2 5.
• Straddling/Overriding valves: One valve may partially or completely "straddle" both ventricles, affecting flow dynamics 1 3 5.

Ventricular Looping and Inversion

The spatial arrangement of the ventricles can be:

• d-loop (noninverted): The usual position, where the morphological right ventricle is on the right.
• l-loop (inverted): The right ventricle is on the left, and the left ventricle is on the right. This inversion changes the pattern of blood shunting and is seen in a significant percentage of DILV cases 1 3 6.

Functional Univentricular Heart

The broader concept of a "univentricular heart" includes DILV and similar conditions where only one ventricle supports systemic circulation, even if both ventricles are present anatomically but one is hypoplastic or non-functional 7.

Causes of Double Inlet Left Ventricle

While DILV is a congenital (present at birth) defect, the precise mechanisms that lead to its development involve complex disruptions in early heart formation.

Cause	Mechanism	Developmental Stage	Source
Embryonic Arrest	Incomplete AV canal widening	Weeks 4–8 gestation	6 8
Septation Failure	Malposition of interventricular septum	Embryogenesis	8
Genetic Factors	Not well established	Unknown	7
Associated Malformations	TGA, valve anomalies	Early development	1 6

Table 3: Causes and Developmental Mechanisms

Embryological Basis

DILV likely arises from a partial arrest in normal heart development. During embryogenesis (weeks 4–8 of gestation), the heart's atrioventricular canal is supposed to widen and divide, allowing each atrium to connect to its corresponding ventricle. In DILV, both atria remain connected predominantly to the morphological left ventricle, reflecting a developmental stage seen in early human embryos 6.

Septation Abnormalities

Normal division (septation) of the ventricles is crucial for creating a four-chambered heart. In DILV, either the interventricular septum doesn't form properly or is malpositioned, preventing the right ventricle from receiving its usual atrial inflow 8.

Genetic and Environmental Factors

No single gene or environmental factor has been conclusively linked to DILV, but as with many congenital heart defects, a combination of genetic susceptibility and environmental influences during early pregnancy is suspected 7.

Associated Malformations

DILV rarely occurs in isolation. Commonly associated anomalies include:

• Transposition of the great arteries (TGA)
• Malformations of atrioventricular valves
• Outflow tract obstructions (pulmonary or aortic stenosis)
• Hypoplasia or malformation of the right ventricle

These additional abnormalities further complicate both the clinical picture and surgical approach 1 6.

Treatment of Double Inlet Left Ventricle

Treatment for DILV is highly individualized, requiring a staged surgical approach and lifelong follow-up. The primary goal is to optimize oxygen delivery and prevent complications, as true anatomical correction is generally not possible.

Approach	Purpose	Outcome/Notes	Source
Medical Management	Stabilize heart failure	Temporary	3 13
Staged Palliation	Control pulmonary/systemic flow	Standard of care	13 14
Fontan Procedure	Systemic venous return to pulmonary arteries	Long-term palliation, improved survival	10 11 13
Ventricular Septation	Create two-ventricle circulation	Rarely feasible	9 12
Heart Transplant	End-stage or failed Fontan	Limited cases	13

Table 4: Treatment Strategies for DILV

Medical Management

Initially, infants may require medical therapy to control symptoms of heart failure or to stabilize oxygenation. This can include diuretics, inotropes, and other supportive measures. However, medical management is usually a bridge to surgical intervention 3 13.

Staged Surgical Palliation

Due to the complexity of DILV, a staged surgical approach is the standard of care:

• Stage 1 (Neonatal): Procedures such as the Blalock-Taussig shunt (to increase pulmonary flow), pulmonary artery banding (to reduce excessive flow), or the Norwood procedure (in cases with aortic arch obstruction) 13 14.
• Stage 2 (Infancy): Bidirectional Glenn or hemi-Fontan procedure, connecting the superior vena cava to the pulmonary arteries, reducing the volume load on the single ventricle 13 14.
• Stage 3 (Childhood): Fontan procedure, redirecting all systemic venous blood to the pulmonary arteries, bypassing the heart and allowing the single ventricle to support systemic circulation 10 11 13.

The Fontan Procedure

The Fontan operation is the definitive palliative surgery for most patients with DILV. It has significantly improved long-term survival and quality of life:

• Survival rates: Early operative mortality has decreased to below 10%, and long-term survival at 10 years exceeds 70% in many series 10 11 13.
• Late complications: Arrhythmias, protein-losing enteropathy, and thromboembolic events remain risks, highlighting the need for ongoing specialist follow-up 10 11.

Ventricular Septation

In rare cases with favorable anatomy, a surgical attempt is made to create a two-ventricle circulation (ventricular septation). However, this approach is only suitable for select patients and carries higher risk, especially if performed late due to progressive ventricular hypertrophy 9 12.

Heart Transplantation

For patients with failed Fontan circulation, severe ventricular dysfunction, or intractable arrhythmias, heart transplantation may be considered. This remains a last-resort option due to the complexity and scarcity of donor organs 13.

Advances and Prognosis

Modern surgical and medical care has dramatically improved outcomes for DILV. Ten-year survival rates now approach 90% in many specialized centers, with most survivors reporting good to excellent quality of life. Morphologic and surgical factors have less impact on outcome than previously thought, thanks to individualized, multidisciplinary care 13 14.

Conclusion

Double Inlet Left Ventricle is a rare but serious congenital heart defect, demanding expertise across diagnosis, surgical management, and lifelong care. Advances in surgical techniques—especially the staged Fontan pathway—have transformed prognosis for many children born with this condition. Ongoing research continues to refine our understanding, offering hope for even better outcomes in the future.

Main Points:

• DILV presents with early cyanosis, heart failure, and murmur; symptoms vary widely.
• There are multiple anatomical types, with most cases involving transposed great arteries and complex valve arrangements.
• The condition arises from embryological arrest and septation failure, often with additional cardiac malformations.
• Staged surgical palliation, culminating in the Fontan procedure, is the standard of care and offers excellent long-term outcomes for most.
• Continued follow-up is essential to monitor for late complications and optimize quality of life.

Understanding DILV in all its complexity is the key to empowering affected families and supporting the best possible care throughout life.