Tetralogy of Fallot
The tetralogy of Fallot (also tetralogy of Fallot ) is a congenital heart malformation, which accounts for about 10 % of congenital heart defects. It consists of four components (hence, tetralogy ): pulmonary stenosis, a ventricular septal defect, a riding on the septum aorta and a subsequent right heart.
The name of this heart defect goes to the French pathologist Étienne -Louis Arthur Fallot back as first described ( 1888). The common also in German among medical abbreviation ToF derived from English Tetralogy of Fallot.
Formation
At the end of the fifth week of development the outflow tract of the heart arises from yet from both sides of the heart. By forming Endokardwülsten in Conus cordis septum arises aorticopulmonale that the conus cordis into right and left outflow tract shares (aorta and pulmonary artery ). Shifts, however, the septum aorticopulmonale forward, narrowed the chamber outflow area ( pulmonary stenosis ), the septum, however, is still open ( septal ). The aorta arises now from both ventricles ( riding aorta). Through the pulmonary stenosis it comes to high blood pressure ( hypertension ) in the right ventricle. So that sufficient blood can be pumped out of the heart, the chamber wall ( hypertrophied right ventricle) increased.
The malformations
The following malformations constitute the clinical picture:
Pulmonary stenosis
The pulmonary stenosis as narrowing of the output tract of the right ventricle to the lungs. The individual components of this outflow tract ( proximal cardiac portion, the valve ring with half-moon shaped flaps ( semilunares ) and lung near portion) may differ greatly narrowed. The actual pulmonary valve is often ill- formed and has only two half-moon flap in about 60 % of cases. Therefore, the severity of valve narrowing can vary greatly. The Pulmonalgefäßsystem is - under generally developed - in accordance with the restrictions in the entire outflow tract.
Ventricular septal defect
The ventricular septal defect is a hole in the septum between the ventricles that is not a lack of substance of the ventricular septum is in the tetralogy of Fallot, but was created by the malformation of the heart. He is usually just below the right ventricular outflow tract ( pulmonary valve ) and near the aortic valve ( waste gate for the systemic circulation ) and the tricuspid valve ( valve between the right atrium and right main chamber ).
About Riding the aorta
Due to a lack of rotation of the Pulmonalgefäßes in cardiac development, the aortic root is positioned in its relation to the right ventricle, so that "over- riding of the aorta " result over the ventricular septal defect.
Right heart
The right heart, a heart activity hindering growth of the muscle mass of the right heart due to the chronic overload, may initially be small, but increase over time.
Consequences for the cardiovascular system
The over the right atrium returning from the body is low in oxygen (venous ) blood passes due to the narrowing of the pulmonary outflow tract only partially into the lungs, there to be charged with oxygen. A correspondingly greater proportion deviates from across the ventricular septal defect and flows bypassing the pulmonary circulation directly via the aorta (large aorta ) back into the body. Such a transfer of blood from the right heart directly into the systemic circulation is called right-left shunt. By the mixture of oxygen-depleted blood via the shunt with the returning oxygen-rich blood from the lungs results in a cyanosis. This is on a blue coloration of the skin and mucous membranes, mainly to mouth and hands / feet visible by the lack of oxygen in the systemic circulation. You may be more or less pronounced depending on the amount of trespassing blood and may only load visible ( in young children drinking or crying ). If the cyanosis low, one also speaks of a "pink tetralogy ".
The lack of oxygen in the blood, the body reacts with an increase in the erythrocytes (red blood cells). Within certain limits can thus be compensated the oxygen deficit. But the viscosity of the blood is also changed and it can form small clots that can cause an embolism. The growth of small blood vessels in the fingers and toes increases. It can develop " clubbing " and " Watchglass ". Because of the deterioration in viscosity of the blood should be offered to children getting enough to drink.
Hypoxemic seizures
A special feature of tetralogy of Fallot are hypoxic seizures. They occur only in a small proportion of children are rarely seen in children with other cyanotic heart defects. In such an attack, the children are restless and anxious, cyanosis increases, the heart rate increases to values between 140 to 160 beats / minute. The children can appear gray - pale - blue and consciousness is clouded, to unconsciousness. The seizures usually develop without apparent external causes and the cause is not always clearly identifiable.
The pediatric cardiologist will inform the parents on this complication and if there is suspicion of a hypoxic seizure is, the child belongs to the clinic. His appearance usually requires a speedy operation. At-home fresh air and a sedative is suitable as first aid. In the clinic, an attack with oxygen doses, sedation is medication (such as opioids) and the administration of beta blockers ( propranolol about, may act prophylactically ) treated.
Diagnostics
For the diagnosis today the echocardiography and the early cardiac catheterization available.
Therapy
In order to achieve a higher age for the correction, a Blalock - Taussig first anastomosis is often applied. Treatment consists of surgical correction. The aim is to create a normal anatomy. The pulmonary stenosis is extended and the ventricular septal defect through a patch ( patch ) - closed so that the aorta receives only oxygen-rich blood from the left ventricle (heart chamber ) - usually from pericardium or Gore-Tex. The aim is an operation in one step - today (2007) in their first year. But it depends on the individual factors in the patient, if this procedure is possible. In special situations it can today still be displayed, preceded by a palliative operation by investing an aorto - pulmonary shunt the main operation. Most commonly, a modified Blalock - Taussig shunt in the form of a Goretex prosthesis between the innominate artery and right pulmonary artery or a central shunt between the aorta and pulmonary artery is created. This operation is considered to be lighter and intervention is performed usually without using the heart - lung machine. Thus, the pulmonary blood flow is increased, thereby improving the oxygen supply. At the later definitive surgery, the shunt is closed again. In some cases, the surgery for a few weeks or months, in one infant in the context of a cardiac catheter intervention in the form of " tearing " of the pulmonary stenosis with a balloon be postponed.
Treatment results and check-ups
Usually it comes after surgery for a complication-free course and the ventricles can develop normally. Regular checks (every six to twelve months, life- long) by the pediatric cardiologist should definitely be performed in order to observe a possibly remaining small pulmonary stenosis or leakage of the valve. Also on occurring cardiac arrhythmia is taken at these check-ups. Endocarditis should be considered for life.
It is expected that develop the children today operated normally and reach a normal exercise tolerance and quality of life in adulthood. However, the course, as with all complex congenital heart defects, be different. Previously operated patients in whom the correction operation was carried out for technical reasons (lack of early diagnosis and surgical options ) only in childhood or adolescence are, may not be compared with today operated children.