A ventricular outflow tract obstruction is a heart condition in which either the right or left

ventricular outflow tract A ventricular outflow tract is a portion of either the left ventricle or right ventricle of the heart through which blood passes in order to enter the great arteries. The right ventricular outflow tract (RVOT) is an infundibular extension of the ...

is blocked or obstructed. These obstructions represent a spectrum of disorders. Majority of these cases are

congenital A birth defect, also known as a congenital disorder, is an abnormal condition that is present at birth regardless of its cause. Birth defects may result in disabilities that may be physical, intellectual, or developmental. The disabilities can ...

, but some are acquired throughout life. __TOC__

Different types

Right ventricular outflow tract obstruction

A right ventricular outflow tract obstruction (RVOTO) may be due to a defect in the

pulmonic valve The pulmonary valve (sometimes referred to as the pulmonic valve) is a valve of the heart that lies between the right ventricle and the pulmonary artery and has three cusps. It is one of the four valves of the heart and one of the two semilunar v ...

, the supravalvar region, the

infundibulum An infundibulum (Latin for ''funnel''; plural, ''infundibula'') is a funnel-shaped cavity or organ. Anatomy * Brain: the pituitary stalk, also known as the ''infundibulum'' and ''infundibular stalk'', is the connection between the hypothalamus and ...

, or the pulmonary artery. *

Pulmonary atresia Pulmonary atresia is a congenital malformation of the pulmonary valve in which the valve orifice fails to develop. The valve is completely closed thereby obstructing the outflow of blood from the heart to the lungs. The pulmonary valve is located o ...

Pulmonary valve stenosis Pulmonary valve stenosis (PVS) is a heart valve disorder. Blood going from the heart to the lungs goes through the pulmonary valve, whose purpose is to prevent blood from flowing back to the heart. In pulmonary valve stenosis this opening is too ...

Hypoplastic right heart syndrome Hypoplastic right heart syndrome is a congenital heart defect in which the right atrium and right ventricle are underdeveloped. This defect causes inadequate blood flow to the lungs and thus, a blue or cyanotic infant. Symptoms and signs Common s ...

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 ri ...

Left ventricular outflow tract obstruction

A left ventricular outflow tract obstruction (LVOTO) may be due to a defect in the

aortic valve The aortic valve is a valve in the heart of humans and most other animals, located between the left ventricle and the aorta. It is one of the four valves of the heart and one of the two semilunar valves, the other being the pulmonary valve. The ...

, or a defect located at the subvalvar or supravalvar level. *

Aortic valve stenosis Aortic stenosis (AS or AoS) is the stenosis, narrowing of the exit of the left ventricle of the heart (where the aorta begins), such that problems result. It may occur at the aortic valve as well as above and below this level. It typically gets ...

Supravalvar aortic stenosis Supravalvular aortic stenosis is a congenital obstructive narrowing of the aorta just above the aortic valve and is the least common type of aortic stenosis. It is often associated with other cardiovascular anomalies and is one of the characteristi ...

Coarctation of the aorta Coarctation of the aorta (CoA or CoAo), also called aortic narrowing, 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' ...

Hypoplastic left heart syndrome Hypoplastic left heart syndrome (HLHS) is a rare congenital heart defect in which the left side of the heart is severely underdeveloped and incapable of supporting the systemic circulation. It is estimated to account for 2-3% of all congenital hea ...

Hypertrophic cardiomyopathy Hypertrophic cardiomyopathy (HCM, or HOCM when obstructive) is a condition in which the heart becomes thickened without an obvious cause. The parts of the heart most commonly affected are the interventricular septum and the ventricles. This r ...

Pathophysiology

A ventricular outflow tract obstruction means there is a limitation in the blood flow out of either the right or left ventricles of the heart, depending on where the obstruction is. This can lead to

cardiac hypertrophy Ventricular hypertrophy (VH) is thickening of the walls of a ventricle (lower chamber) of the heart. Although left ventricular hypertrophy (LVH) is more common, right ventricular hypertrophy (RVH), as well as concurrent hypertrophy of both ventri ...

dilatation Dilation (or dilatation) may refer to: Physiology or medicine * Cervical dilation, the widening of the cervix in childbirth, miscarriage etc. * Coronary dilation, or coronary reflex * Dilation and curettage, the opening of the cervix and surgic ...

of the heart, and ultimately

heart failure Heart failure (HF), also known as congestive heart failure (CHF), is a syndrome, a group of signs and symptoms caused by an impairment of the heart's blood pumping function. Symptoms typically include shortness of breath, excessive fatigue, a ...

in some cases. The right side of the heart is much smaller and weaker than the left side of the heart. It pumps de-oxygenated blood into the lungs. The left side of the heart is more muscular than the right side of the heart. It pumps oxygenated blood from the lungs into the aorta to perfuse the rest of the body. When the heart has to pump against increased resistance, or

afterload Afterload is the pressure that the heart must work against to eject blood during systole (ventricular contraction). Afterload is proportional to the average arterial pressure. As aortic and pulmonary pressures increase, the afterload increases on ...

, as in the case of a ventricular obstruction, it compensates by growing in size. This adaptation is beneficial to pump blood past the obstruction, but eventually this hypertrophy can lead to other problems including arrhythmias, ischemia, and heart failure.

Hypertrophic cardiomyopathy

hypertrophic cardiomyopathy Hypertrophic cardiomyopathy (HCM, or HOCM when obstructive) is a condition in which the heart becomes thickened without an obvious cause. The parts of the heart most commonly affected are the interventricular septum and the ventricles. This r ...

, there is disorganized production of cardiac myocytes leading to increased septal wall thickness and a pathologic motion of the mitral valve. The anterior mitral valve moves anteriorly during systole in these patients leading to dynamic LVOTO, and the increased mass of the septum leads to a physical narrowing for blood to pass through. Thus, both of these contribute to the left ventricular outflow tract obstruction seen in some cases of this disease. If severe enough, this condition requires prompt treatment, as these patients are at risk for lethal tachyarrythmias.

Aortic valve stenosis

is the most common cause of LVOTO. Aortic valve stenosis means the aortic valve has narrowed and is not opening freely. The aortic valve opens to allow blood to flow from the left ventricle to the aorta. Stenosis here leads to a narrowing of the passage for blood to flow out of the left ventricle, thus a LVOTO. More than 50% of patients with aortic valve stenosis have a congenital heart abnormality called a

bicuspid aortic valve Bicuspid aortic valve (aka BAV) is a form of heart disease in which two of the leaflets of the aortic valve fuse during development in the womb resulting in a two-leaflet (bicuspid) valve instead of the normal three-leaflet (tricuspid) valve. BA ...

. The aortic valve is normally three leaflets but when it is bicuspid it is made of two. This increases the risk for aortic stenosis due to increased stress on the leaflets, calcium deposition, turbulent blood flow, and scarring. If the stenosis is severe enough, surgical intervention may be necessary.

References

Congenital heart defects {{congenital-malformation-stub