CACH (Canadian Adult Congenital Heart) Network A co-operative nation-wide association of Canadian cardiologists, cardiac surgeons, and others, many of whom are situated in regional referral centres for adult congenital heart disease, dedicated to improving the care of ACHD patients.

cardiac position Position of the heart in the chest with regard to its location, and the orientation of its apex.

cardiac location - location of the heart in the chest:
  • levoposition - to the left
  • mesoposition - central
  • dextroposition - to the right
Cardiac location is affected by many factors including underlying cardiac malformation, abnormalities of mediastinal and thoracic structures, tumours, kyphoscoliosis, abnormalities of the diaphragm.

cardiac orientation - the base to apex orientation of the heart:
  • levocardia - apex directed to the left of the midline
  • mesocardia - apex oriented inferiorly in the midline
  • dextrocardia - apex directed to the right of the midline
The base to apex axis of the heart is defined by the alignment of the ventricles and is independent of cardiac situs (sidedness). This axis is best described by echocardiography using the apical and subcostal 4-chamber views.

cardiac sidedness - see situs.

cardiopulmonary study A rest and stress study of cardiopulmonary physiology, including at least the following elements: resting pulmonary function, stress study to assess maximum workload, maximum oxygen uptake (MVO2), anaerobic threshold (AT), and oxygen saturation with effort.

Cardio-SealŪ device A device delivered percutaneously by catheter for closure of an ASD or PFO.

CATCH-22 Syndrome due to microdeletion at chromosome 22q11 resulting in a wide clinical spectrum. CATCH stands for Cardiac defect, Abnormal facies, Thymic hypoplasia, Cleft palate, and Hypocalcemia. Cardiac defects include cono-truncal defects such as interrupted aortic arch, tetralogy of Fallot, truncus arteriosus, and double outlet right ventricle. see also diGeorge syndrome, velo-cardio-facial syndrome.

cat's eye syndrome A syndrome due to a tandem duplication of chromosome 22q or an isodicentric chromosome 22 such that the critical region 22pter -->q11 is duplicated. Phenotypic features include mental deficiency, anal and renal malformations, hypertelorism and others. Total anomalous pulmonary venous return is the commonest congenital cardiac lesion (in up to 40% of patients).

CHARGE association This anomaly is characterized by the presence of coloboma or choanal atresia and three of the following defects: congenital heart disease, nervous system anomaly or mental retardation, genital abnormalities, ear abnormality or deafness. If both coloboma and choanal atresia are both present, only two of the additional (minor) abnormalities are needed for diagnosis. Congenital heart defects seen in the CHARGE association are: tetralogy of Fallot with or without other cardiac defects, atrioventricular septal defect, double outlet right ventricle, double inlet left ventricle, transposition of the great arteries, interrupted aortic arch and others.

Chiari network Fenestrated remnant of the right valve of the sinus venosus resulting from incomplete regression of this structure during embryogenesis and first described in 1897 (Chiari H. Ueber Netzbildungen im rechten Vorhof. Beitr Pathol Anat 1897; 22:1-10). The prevalence is 2% in autopsy and echocardiography studies. It presents with coarse right atrial reticula connected to the Eustachian and Thebesian valves and attached to the crista terminalis. It may be associated with patent foramen ovale and interatrial septal aneurysm.

cleft A-V valve see atrio-ventricular valve; see also atrial septal defect. see also ostium primum ASD.

coarctation of the aorta A stenosis of the proximal descending aorta varying in anatomy, physiology and clinical presentation. It may present with discrete or long-segment stenosis, is frequently associated with hypoplasia of the aortic arch and bicuspid aortic valve and may be part of a Shone complex.


common (as in: a-v valve, atrium, ventricle, etc.)

Implies bilateral structures with absent septation. Contrasts with "single", which implies absence of corresponding contralateral structure. see also single

common atrium Large atrium characterized by a non-restrictive communication between the bilateral atria due to the absence of most of the atrial septum. Frequently associated with complex congenital heart disease (isomerism, atrio-ventricular septal defect, etc.). see also single (atrium).

common arterial trunk see truncus arteriosus.

complete transposition of the great arteries syn classic transposition; d-transposition; d-TGA; atrio-ventricular concordance with ventriculo-arterial discordance. An anomaly wherein the aorta arises from the right ventricle and the pulmonary artery arises from the left ventricle.

concordant atrio-ventricular connections Appropriate connection of morphologic right atrium to morphologic right ventricle and of morphologic left atrium to morphologic left ventricle. syn. atrio-ventricular concordance.
concordant ventriculo-arterial connections Appropriate origin of pulmonary trunk from morphologic right ventricle and of aorta from morphologic left ventricle. syn. ventriculo-arterial concordance.

conduit A structure that connects non-adjacent parts of the cardiovascular system, allowing blood to flow between them. Often fashioned from prosthetic material. May include a valve.

congenital coronary arteriovenous fistula (CCAVF) A direct communication between a coronary artery and cardiac chamber, great artery or vena cava, bypassing the coronary capillary network.

congenital heart disease Anomalies of the heart originating in fetal life. Their expression may, however, be delayed beyond the neonatal period, and may change with time as further post-natal physiologic and anatomic changes occur.

congenitally corrected transposition of the great arteries syn cc-TGA; l-transposition; l-TGA; atrio-ventricular discordance with ventriculo-arterial discordance, double discordance. An anomaly wherein the aorta arises from the right ventricle and the pulmonary artery from the left ventricle, and, in addition, the atrio-ventricular connection is discordant such that the right atrium connects to the left ventricle and the left atrium connects to the right ventricle. There are usually associated anomalies, the most common being VSD, pulmonic stenosis, and/or a hypoplastic ventricle. The right ventricle supports the systemic circulation.

congenital pericardial defect A defect in the pericardium due to defective formation of the pleuro-pericardial membrane of the septum transversum. The spectrum of pericardial deficiency is wide. It may be partial or total. Its clinical diagnosis is difficult. Left-sided defects are more common. Total absence of the pericardium may be associated with other defects such as bronchogenic cyst, pulmonary sequestration, hypoplastic lung, and other congenital heart diseases.

connection Anatomic link between two structures (e.g.: veno-atrial, atrio-ventricular, ventriculo-arterial).

cono-truncal abnormality Neural crest cell migration is crucial for cono-truncal septation and the development of both the pulmonary and aortic outflow tracts. If neural crest cell migration fails, cono-truncal abnormalities occur. The most common cono-truncal anomalies are truncus arteriosus and interrupted aortic arch; other defects may include tetralogy of Fallot, pulmonary atresia with ventricular septal defect, absent pulmonary valve or d-malposition of the great arteries with double outlet right ventricle, single ventricle or tricuspid atresia. Abnormal neural crest migration may also be associated with complex clinical entities, such as CATCH-22.

conus see infundibulum

cor triatriatum A membrane divides the left atrium into an accessory pulmonary venous chamber and a left atrial chamber contiguous with the mitral valve. The pulmonary veins enter the accessory chamber. The connection between the accessory chamber and the true left atrium varies in size and may produce pulmonary venous obstruction.

cor triatriatum dexter Abnormal septation of the right atrium due to failure of regression of the right valve of the sinus venosus. This yields a smooth-walled posteromedial "sinus" chamber (embryologic origin of the sinus venosus) that receives the venae cavae and (usually) the coronary sinus, and a trabeculated anterolateral "atrial" chamber (embryologic origin of the primitive right atrium) that includes the right atrial appendage and is related to the tricuspid valve. Usually, there is free communication between these two compartments but variable obstruction to systemic venous flow from the "sinus" chamber to the "atrial" chamber may occur and may be associated with underdevelopment of downstream right heart structures (e.g. hypoplastic tricuspid valve, tricuspid atresia, pulmonary stenosis or pulmonary atresia). A patent foramen ovale or an ASD are often present in relation to the posteromedial chamber.

When there is more extensive resorption of the right valve of the sinus venosus, remnants form the Eustachian valve related to the inferior vena cava, the Thebesian valve related to the coronary sinus, and the crista terminalis. Chiari network describes right atrial reticula, which are an extensively fenestrated remnant of the right sinus venosus valve. see sinus venosus.


criss-cross heart syn. criss-cross atrio-ventricular connection. A rotational abnormality of the ventricular mass around its long axis resulting in relationships of the ventricular chambers not anticipated from the given atrio-ventricular connections. If the rotated ventricles are in a markedly supero-inferior relationship, the heart may also be described as a supero-inferior or upstairs-downstairs heart. There may be ventriculo-arterial concordance or discordance.

crista supraventricularis see crista ventricularis.

crista terminalis A vestigial remnant of the right valve of the sinus venosus located at the junction of the trabeculated right atrial appendage and the smooth-walled "sinus" component of the right atrium receiving IVC, SVC and the coronary sinus. A feature of right atrial internal anatomy. syn. terminal crest.

crista ventricularis A saddle-shaped muscular crest in the right ventricular outflow tract intervening between the tricuspid valve and the pulmonary valve, consisting of septal and parietal components, which demarcates the junction between the outlet septum and the pulmonary infundibulum. Less commonly but more accurately termed crista supraventricularis.

cyanosis A bluish discoloration due to the presence of an increased quantity of desaturated hemoglobin in tissues. In congenital heart disease cyanosis is generally due to right to left shunting through congenital cardiac defects, bypassing the pulmonary alveoli, or due to acquired intrapulmonary shunts (central cyanosis). Cyanosis can also occur due to increased peripheral extraction due, for instance, to critically reduced cutaneous flow (peripheral cyanosis).