Vascular ring is an abnormal formation of the aorta, the large artery that carries blood from the heart to the rest of the body. It is a congenital problem, which means it is present at birth.
See also: Double aortic arch
Alternative NamesRight aortic arch with aberrant subclavian and left ligamentum
Causes, incidence, and risk factorsVascular ring is rare. It accounts for less than 1% of all congenital heart problems. The condition occurs as often in males as females. Some infants with vascular ring also have another congenital heart problem.
Vascular ring occurs very early in the baby's development in the womb. Normally, the aorta develops from one of several curved pieces of tissue (arches). The body breaks down some of the remaining arches, while others form into arteries. Some arteries that should break down do not; this forms vascular rings.
With vascular ring, some of the arches and vessels that should have changed into arteries or disappeared are still present when the baby is born. These arches form a ring of blood vessels, which encircles and presses down on the windpipe (trachea) and esophagus.
Several different types of vascular ring exist. In some types, the vascular ring only partially encircles the trachea and esophagus, but it still can cause symptoms.
SymptomsSome children with a vascular ring never develop symptoms. However, in most cases, symptoms are seen during infancy. Pressure on the windpipe (trachea) and esophagus can lead to breathing and digestive problems. The more the ring presses down, the more severe the symptoms will be.
Breathing problems may include:
Eating may make breathing symptoms worse.
Digestive symptoms are rare, but may include:
The doctor will listen to the baby's breathing to rule out other breathing disorders such as Asthma. Listening to the child's heart through a stethoscope can help identify murmurs and other heart problems.
The following tests can help diagnose vascular ring:
Surgery is usually performed as soon as possible on children with symptoms. The goal of surgery is to split the vascular ring and relieve pressure on the surrounding structures. The surgery is not very invasive. The procedure is usually done through a small surgical cut in the left side of the chest between the ribs.
Changing the child's diet may help relieve the digestive symptoms of vascular ring. The doctor will prescribe medications (such as antibiotics) to treat any respiratory tract infections, if they occur.
Children who don't have symptoms may not need treatment, but should be carefully watched to make sure the condition doesn't become worse.
Expectations (prognosis)How well the infant does depends on how much pressure the vascular ring is putting on the esophagus and trachea and how quickly the infant is diagnosed and treated.
Surgery works well in most cases and often relieves symptoms right away. Severe breathing problems may take months to go away. Some children may continue to have loud breathing, especially when they are very active or have respiratory infections.
ComplicationsDelaying surgery can lead to serious complications such as damage to the trachea and even death. Calling your health care providerCall your health care provider if your baby has symptoms of vascular ring. Getting diagnosed and treated quickly can prevent serious complications. PreventionThere is no known way to prevent this condition. ReferencesOther congenital heart and vascular malformations. In: Kliegman RM, Behrman RE, Jenson HB, Stanton BF, eds. Nelson Textbook of Pediatrics. 18th ed. Philadelphia, Pa: Saunders Elsevier; 2007chap 432.
in a ring shape
They form a ring where phloem forms an outer ring around the xylem.
A dicot plant. This arrangement of vascular bundles is a characteristic feature of dicot plants, where the xylem is located towards the center and the phloem towards the outside of the stem, forming a ring. This organization allows for efficient transport of water and nutrients throughout the plant.
The structure of a stem has different intereal structures. They have vascular tissues. Stems have a bundled arrangement of circular vascular tissues. The xylem and phloem are in a circle of vascular tissues that form a ring around cortex.
The band of vascular tissue formed during each growing season is called the growth ring or annual ring. These rings can be seen in the cross-section of a tree trunk and can be used to determine the age of the tree and its growth patterns.
The parenchyma cells inside the ring of vascular tissue in dicot stems are known as pith. Pith cells are involved in storage of nutrients, water transport, and provide mechanical support to the stem.
In monocot stems, vascular bundles are scattered throughout the ground tissue. They are not arranged in a distinct pattern like in dicot stems where they form a ring. The scattered distribution of vascular bundles provides support and strength to the stem.
The vascular bundles would be arranged in a ring around the pith. The flower would be a dicot, because the four characteristics of dicots are: ~flower parts in fours or fives ~two cotyledons (embryonic leaves) ~veins in leaves branch out ~vascular bundles are arranged in a ring
the stone canal connects the madreporite to the ring canal and the ring canal allows water to flow into the radial canals, just tubes...
In dicotyledonous roots, vascular bundles are arranged in a distinct pattern called the radial arrangement. The xylem is found in the center of the root, forming a solid core, while the phloem surrounds the xylem in a ring formation. This radial arrangement allows for efficient transport of water and nutrients throughout the root.
In monocot stems, vascular bundles are scattered throughout the ground tissue. They are arranged in a complex pattern, with the xylem positioned towards the center and the phloem towards the periphery. This arrangement provides strength and flexibility to the stem.
The vascular bundles in a monocot herbaceous stem are said to be scattered, because they lack the organization of the dicot vascular bundles. Dicot vascular bundles are arranged in a star shaped formation, whereas the monocot vascular bundles are placed randomly.