Aortopulmonary window (APW) is a faulty connection between the

aorta The aorta ( ; : aortas or aortae) is the main and largest artery in the human body, originating from the Ventricle (heart), left ventricle of the heart, branching upwards immediately after, and extending down to the abdomen, where it splits at ...

and the main

pulmonary artery A pulmonary artery is an artery in the pulmonary circulation that carries deoxygenated blood from the right side of the heart to the lungs. The largest pulmonary artery is the ''main pulmonary artery'' or ''pulmonary trunk'' from the heart, and ...

that results in a significant

left-to-right shunt In cardiology, a cardiac shunt is a pattern of blood flow in the heart that deviates from the normal circuit of the circulatory system. It may be described as right-left, left-right or bidirectional, or as systemic-to-pulmonary or pulmonary-to-s ...

. The aortopulmonary window is the rarest of septal defects, accounting for 0.15-0.6% of all congenital heart malformations. An aortopulmonary window can develop alone or in up to 50% of cases alongside other cardiac defects such as

interrupted aortic arch Interrupted aortic arch is a very rare heart defect (affecting 3 per million live births) in which the aorta is not completely developed. There is a gap between the ascending and descending thoracic aorta. In a sense it is the complete form of a coa ...

coarctation of the aorta Coarctation of the aorta (CoA) is a congenital condition whereby the aorta is narrow, usually in the area where the ductus arteriosus ( ligamentum arteriosum after regression) inserts. The word ''coarctation'' means "pressing or drawing toget ...

, transposition of great vessels, and

tetralogy of Fallot Tetralogy of Fallot (TOF), formerly known as Steno-Fallot tetralogy, is a congenital heart defect characterized by four specific cardiac defects. Classically, the four defects are: * Pulmonary stenosis, which is narrowing of the exit from the r ...

Signs and symptoms

can cause

heart failure Heart failure (HF), also known as congestive heart failure (CHF), is a syndrome caused by an impairment in the heart's ability to Cardiac cycle, fill with and pump blood. Although symptoms vary based on which side of the heart is affected, HF ...

, with symptoms such as

tachypnea Tachypnea, also spelt tachypnoea, is a respiratory rate greater than normal, resulting in abnormally rapid and shallow breathing. In adult humans at rest, any respiratory rate of 1220 per minute is considered clinically normal, with tachypnea b ...

, poor eating, and

diaphoresis Perspiration, also known as sweat, is the fluid secreted by sweat glands in the skin of mammals. Two types of sweat glands can be found in humans: eccrine glands and apocrine glands. The eccrine sweat glands are distributed over much of the ...

Dyspnea Shortness of breath (SOB), known as dyspnea (in AmE) or dyspnoea (in BrE), is an uncomfortable feeling of not being able to breathe well enough. The American Thoracic Society defines it as "a subjective experience of breathing discomfort that ...

and indications of laborious breathing can be caused by low lung compliance and increased

airway resistance In respiratory physiology, airway resistance is the resistance of the respiratory tract to airflow during inhalation and exhalation. Airway resistance can be measured using plethysmography. Definition Analogously to Ohm's law: :R_ = \frac Where: ...

. Infants may have

failure to thrive Failure to thrive (FTT), also known as weight faltering or faltering growth, indicates insufficient weight gain or absence of appropriate physical growth in children. FTT is usually defined in terms of weight, and can be evaluated either by a low ...

as well as recurrent

pneumonia Pneumonia is an Inflammation, inflammatory condition of the lung primarily affecting the small air sacs known as Pulmonary alveolus, alveoli. Symptoms typically include some combination of Cough#Classification, productive or dry cough, ches ...

. Findings among individuals with an isolated aortopulmonary window vary based on the size of the defect and the

pulmonary vascular resistance Vascular resistance is the resistance that must be overcome for blood to flow through the circulatory system. The resistance offered by the systemic circulation is known as the systemic vascular resistance or may sometimes be called by another ter ...

. Cardiac examination typically indicates a parasternal lift resulting from

right ventricular A ventricle is one of two large chambers located toward the bottom of the heart that collect and expel blood towards the peripheral beds within the body and lungs. The blood pumped by a ventricle is supplied by an atrium, an adjacent chamber in t ...

overload, a loud single second

heart sound Heart sounds are the noises generated by the beating heart and the resultant flow of blood through it. Specifically, the sounds reflect the turbulence created when the heart valves snap shut. In cardiac auscultation, an examiner may use a stetho ...

induced by

pulmonary hypertension Pulmonary hypertension (PH or PHTN) is a condition of increased blood pressure in the pulmonary artery, arteries of the lungs. Symptoms include dypsnea, shortness of breath, Syncope (medicine), fainting, tiredness, chest pain, pedal edema, swell ...

, and increased peripheral pulses. When the defect is larger,

may continue to be elevated in the initial weeks or months of life, and there is a modest amount of pulmonary overcirculation. A rather faint basal systolic ejection murmur without a diastolic element and a loud single second heart sound develop due to mild overcirculation. As the

decreases throughout the first few months, the left-to-right shunting of blood into the lungs increases, and the systolic murmur becomes more intense and longer, eventually extending into diastole and becoming a continuous murmur.

Complications

Because there is a pressure gradient from the

to the

throughout systole and diastole, a small aortopulmonary defect may produce a murmur similar to a

patent ductus arteriosus Patent ductus arteriosus (PDA) is a medical condition in which the ''ductus arteriosus'' fails to close after childbirth, birth: this allows a portion of oxygenated blood from the left heart to flow back to the lungs from the aorta, which has a h ...

. When a large defect is left unrepaired,

Eisenmenger syndrome Eisenmenger syndrome or Eisenmenger's syndrome is defined as the process in which a long-standing left-to-right cardiac shunt caused by a congenital heart defect (typically by a ventricular septal defect, atrial septal defect, or less commonly, pa ...

will develop with reversal of the shunt. Untreated cases with major malformations have a poor prognosis, with 40% dying within their first year of life.

Diagnosis

Physical examination findings,

ECG Electrocardiography is the process of producing an electrocardiogram (ECG or EKG), a recording of the heart's electrical activity through repeated cardiac cycles. It is an electrogram of the heart which is a graph of voltage versus time of ...

, and imaging are used to diagnose aortopulmonary window. An electrocardiogram reveals

right ventricular hypertrophy Right ventricular hypertrophy (RVH) is a condition defined by an abnormal enlargement of the cardiac muscle surrounding the right ventricle. The right ventricle is one of the four chambers of the heart. It is located towards the right lower chambe ...

or biventricular hypertrophy.

Cardiomegaly Cardiomegaly (sometimes megacardia or megalocardia) is a medical condition in which the heart becomes enlarged. It is more commonly referred to simply as "having an enlarged heart". It is usually the result of underlying conditions that make the h ...

, a big main

segment, and enhanced pulmonary vascular marking are all visible on a

chest x-ray A chest radiograph, chest X-ray (CXR), or chest film is a Projectional radiography, projection radiograph of the chest used to diagnose conditions affecting the chest, its contents, and nearby structures. Chest radiographs are the most common fi ...

Differential diagnosis

The appearance of aortopulmonary window has similarities to that of

truncus arteriosus The truncus arteriosus is a structure that is present during embryonic development. It is an arterial trunk that originates from both ventricles of the heart that later divides into the aorta and the pulmonary trunk. Structure The truncus arteri ...

ventricular septal defect A ventricular septal defect (VSD) is a defect in the ventricular septum, the wall dividing the left and right ventricles of the heart. It's a common heart problem present at birth ( congenital heart defect). The extent of the opening may vary ...

, and large

. A two-dimensional

echocardiogram Echocardiography, also known as cardiac ultrasound, is the use of ultrasound to examine the heart. It is a type of medical imaging, using standard ultrasound or Doppler ultrasound. The visual image formed using this technique is called an echo ...

can detect and distinguish between these problems.

Treatment

Corrective heart surgery, which is normally performed in the first year of life, is the definitive intervention for an aortopulmonary window. If the patient's symptoms don't allow for corrective surgery, medical therapy of

congestive heart failure Heart failure (HF), also known as congestive heart failure (CHF), is a syndrome caused by an impairment in the heart's ability to fill with and pump blood. Although symptoms vary based on which side of the heart is affected, HF typically pr ...

is the second choice. Permanent alterations in the pulmonary vasculature can be prevented with early intervention.

References

External links

{{DEFAULTSORT:Aortopulmonary Window Radiology Congenital heart defects