The conus artery is a small early branch off the right coronary artery (RCA) circulation.
The artery has a variable distribution, but usually supplies a region of the anterior interventricular septum and the conus of the main pulmonary artery (hence its name).
Coronary arterial dominance is defined by the vessel which gives rise to the posterior descending artery (PDA), which supplies the myocardium of the inferior 1/3rd of the interventricular septum.
Most hearts (80-85%) are right dominant where the PDA is supplied by the RCA. The remaining 15-20% ...
Coronary arterial ectasia (CAE) refers to diffuse dilatation of the coronary arteries. Under some classification systems there is some overlap with the term coronary arterial aneurysms (which is a more focal dilatation).
It is often defined as dilatation of an arterial segment to a...
The coronary arteries arise from the coronary sinuses immediately distal (superior) to the aortic valve and supply the myocardium with oxygenated blood. They branch and encircle the heart to cover its surface with a lacy network resembling perhaps a slightly crooked crown.
Coronary arteriovenous fistulas (CAVFs) are rare coronary artery anomalies whereby there is a fistula between a coronary artery and, most commonly, the right side of the cardiac circulation.
Although a CAVF, in the strictest sense of the term, implies a communication between the c...
Coronary artery aneurysms are an uncommon, predominantly incidental finding.
Coronary artery aneurysms are most common in men 3, likely reflecting the increased rates of atherosclerosis in men compared to women. Prevalence varies in the literature between 0.1-5% 4.
A coronary artery bypass graft (CABG or CAG) is placed during a surgical procedure to increase blood flow to the myocardium due to coronary stenoses, usually caused by coronary artery disease. Arteries or veins can be grafted during this procedure.
Long term outcome of coronary artery bypass gr...
Coronary artery calcification is a common incidental finding in asymptomatic patients having CT of the thorax for non-cardiac indications as well as being a significant finding on cardiac CT. Coronary artery calcification is a marker of atherosclerotic plaque and thus coronary heart disease risk...
Coronary artery disease (CAD) is the leading cause of mortality globally.
CAD is asymptomatic in most of the population. When severe enough it can cause angina or an acute coronary syndrome including myocardial infarction. CAD may also present with heart failure or sudde...
Coronary Artery Disease - Reporting and Data System (CAD-RADSTM) classification is proposed by the Society for Cardiovascular Computed Tomography (SCCT), the American College of Radiology (ACR), and the North American Society for Cardiovascular Imaging (NASCI), last updated in 2016.
Coronary artery dissection (also known as spontaneous coronary artery dissection or SCAD) is a rare cause of acute coronary syndrome especially in young patients who are otherwise healthy.
Coronary artery dissection occurs mainly in young, otherwise health patients especially in f...
Microvascular obstruction (MVO), also known as no reflow phenomenon, is an established complication encountered in coronary angioplasty for prolonged acute myocardial infarction.
The phenomenon results from obstruction of the myocardial microcirculation, which is composed of vessel...
Coronary MR angiography (coronary MRA) is a developing approach to imaging the coronary arteries.
Advantages of coronary MRA include avoidance of the intravenous iodinated contrast and ionizing radiation used in coronary CT angiography and conventional angiography.
A disadvantage of coronary M...
A coronary ostial dimple is a type of congenital coronary artery anomaly where there is a rudiment of the coronary ostium usually followed more distally by proximal coronary stem atresia.
The coronary sinus is the major coronary vein. It returns the majority of the left ventricular blood flow to the right atrium.
The coronary sinus courses along the posterior wall of the left atrium into the left atrioventricular groove. It normally drains into the right atrium. T...
The coronary veins return deoxygenated blood from the myocardium back to the right atrium. Most venous blood returns via the coronary sinus. Coronary venous anatomy is highly variable, but is generally comprised of three groups:
cardiac veins which drain into the coronary sinus:
great cardiac ...
Cor pulmonale is defined as a failure of the structure and function of the right ventricle in the absence of left ventricular dysfunction. It is caused by an underlying primary disorder of the respiratory system. It has a generally chronic and slowly progressive course, although acute onset or w...
Cor triatriatum is an extremely rare and serious congenital cardiac anomaly.
It is thought to account for ~0.1% of all congenital cardiac anomalies 3,4.
Clinical presentation depends on:
degree of stenosis in the fibromuscular membrane
the integrity of ...
A coumadin ridge, also called warfarin ridge or left lateral ridge, is a band-like embryological remnant in the left atrium between the left superior pulmonary vein and the left atrial appendage. It is considered an anatomical variant.
The ridge is formed by the coalition of the left superior ...
The crista terminalis is a smooth muscular ridge in the superior aspect of right atrium. It represents the junction between the sinus venosus and the heart. It divides the pectinate muscle origin and the right atrial appendages in the right atrium.
Its identification is significant in the deter...
This is a basic article for medical students and other non-radiologists
Chest CT is a computed tomography examination of the thoracic cavity performed for a variety of reasons, from suspected cancer to penetrating chest trauma.
A CT chest can be performed with or without IV contrast and when I...
A number of entities can present as cyanotic congenital heart disease. These can be divided into those with increased or decreased pulmonary vascularity (pulmonary plethora):
increased pulmonary vascularity
total anomalous pulmonary venous return (TAPVR) (types I and II)
transposition of the ...
Danon disease is an X-linked dominant cause of debilitating cardioskeletal myopathy.
Although considered rare, the exact incidence is unknown 1.
Danon disease is characterised by the triad of 1-4:
the most prominent clinical feature, and ma...
Deductive echocardiography is a step-by-step approach in diagnosing and differentiating congenital heart disease.
position of heart
Delayed myocardial enhancement, as seen on cardiac MRI, occurs when gadolinium contrast material seeps into fibrotic or necrotic myocardial tissue. It is due to a number of aetiologies, and has variable appearances.
subendocardial enhancement indicates an ischaemic aetiology
Delayed myocardial enhancement can occur in cardiac MR assessment due to a number of causes.
myocardial ischaemia: typically subendocardial and follows a vascular territory 1
non-ischaemic dilated cardiomyopathy
Atrial situs refers to the relative position of the cardiac atria in relation to abdominal viscera and the midline.
Identification of atrial situs is an important initial step in the antenatal and postnatal diagnosis of cardiac structural and situs anomalies.
Dextrocardia is a congenital cardiac malrotation in which the heart is situated on the right side of the body (dextroversion) with the apex pointing to the right.
Dextrocardia is believed to occur in approximately 1 in 12,000 people 2.
There are two main types of dextr...
Diagonal branches of the left anterior descending coronary artery supply blood flow to the anterior and anterolateral walls of the left ventricle. There are usually denoted as D1, D2, D3, etc.
There are termed "diagonal" due to them branching from their parent vessel at acute angles. They ext...
Diastolic pseudogating appears as periodic bright and dark signal in arteries such as the aorta as one progresses through a series of images. Synchronization of the cardiac cycle and the pulse sequence results in high signal in the artery during diastole when blood is relatively stationary and l...
A small cardiothoracic ratio (CTR) as defined as <42%/0.42 when assessed on a PA chest radiograph, and can be due to number of entities:
adrenal insufficiency, e.g. Addison disease
asthmatic paroxysm ...
Dilated cardiomyopathy (DCM) is defined as left ventricular chamber dilation with decreased systolic function (FEVG <40%). There may also be right ventricular dysfunction. Causes are related to intrinsic myocardial damage.
There are dilated, thin-walled, poorly contracting ventricles...
The double-density sign is seen on frontal chest radiographs in the presence of left atrial enlargement, and occurs when the right side of the left atrium pushes behind the right cardiac shadow, indenting the adjacent lung and forming its own distinct silhouette 1-3.
If large enough, the left ...
The double density sign, also sometimes clumsily referred to as the hotter spot within hot area sign, is a bone scan sign of an osteoid osteoma.
It refers to a central focus of intense uptake (the nidus) within a surrounding lower, but nonetheless increased uptake, rim.
Double oblique is a type of multiplanar reconstruction used in cardiac cross-sectional imaging. It is useful for an accurate assessment of the ascending aorta and aortic annulus, and is particularly useful for pre- and post-procedure evaluation of a transcatheter aortic valve replacement (TAVR)....
Double outlet left ventricle (DOLV) is an extremely rare congenital cardiac anomaly where both the aorta and pulmonary trunk arise from the anatomical left ventricle. It is usually classified as a conotruncal anomaly and is often associated with a ventricular septal defect with normal continuity...
Double outlet right ventricle (DORV) is a congenital cardiac anomaly where both the aorta and pulmonary trunk arise from the morphologically right ventricle. It is reported to account for ~2% of congenital cardiac defects 1. It is usually classed as a conotruncal anomaly. There is almost always ...
The double switch procedure is a surgical technique used to repair congenitally corrected transposition of the great arteries (L-TGA), which is a cardiovascular anomaly with atrioventricular and ventriculoarterial discordance.
The procedure consists of any of the following surgical combinations...
Down syndrome (or trisomy 21) is the most common trisomy and also the commonest chromosomal disorder. It is a major cause of intellectual disability, and also has numerous multi-system manifestations.
According to the world health organisation (WHO), the approximate worldwide inci...
Dressler syndrome (DS) is a delayed immune-mediated or secondary pericarditis developing weeks to months after a myocardial infarction (MI).
Dressler syndrome is not to be confused with pericarditis epistenocardica (which is seen earlier in the post-MI period) and is considered a r...
Drug and toxin induced pulmonary hypertension is one of the causes of pulmonary arterial hypertension. It falls under group 1.3 under the Dana point classification system of pulmonary hypertension.
A wide range of difference drugs have been associated with developing pulmonary hyper...
D-SPECT represents the next step in the evolution of SPECT technology and is based on a unique acquisition geometry. It has nine arrays of cadmium zinc telluride (CZT) detectors, each of which rotates around its central axis with programmable angular rotation 1. The detectors are very compact al...
Duchenne muscular dystrophy (DMD) is a dystrophinopathy and the most common muscular dystrophy.
DMD has an incidence of 1 in 3500 to 5000 males 1,2. The condition is extremely rare in females due to its inheritance pattern, as discussed below 1.
The ductus arteriosum (or arteriosus) is the thick short conduit for blood to bypass the non-ventilated lungs in the fetus. It is located between and connects the proximal left pulmonary artery and the undersurface of the aortic arch distal to the origin of the last branch of the arch, at the ao...
The Duke criteria are a set of clinical criteria set forward for the diagnosis of infective endocarditis
For diagnosis the requirement is:
2 major and 1 minor criteria or
1 major and 3 minor criteria or
5 minor criteria
positive blood cultures for infective endocarditis
Dysphagia megalatriensis, also known as cardiovascular dysphagia or cardiac dysphagia, is an impairment of swallowing due to oesophageal compression from a dilated left atrium.
Presentation is generally with mild dysphagia, although a minority of patients will have dysph...
The earth-heart sign is a newly recognised sign of cardiac compromise that may be seen on chest radiographs of patients with tension pneumomediastinum.
The substantial pressure exerted on the heart by the gas trapped in the mediastinum with subsequent impairment of central venous return and obs...
Ebstein anomaly is an uncommon congenital cardiac anomaly, characterised by a variable developmental anomaly of the tricuspid valve.
The anomaly accounts for only ~0.5% of congenital cardiac defects 6-7, although it is the most common cause of congenital tricuspid regurgitation. T...
Echogenic intracardiac focus (EIF) is a relatively common sonographic observation that may be present on an antenatal ultrasound scan.
They are thought to be present in ~4-5% of karyotypically normal fetuses. They may be more common in the Asian population 5.
Ectopia cordis is an extremely rare congenital malformation where the heart is located partially or totally outside the thoracic cavity. The four main ectopic positions are:
adjacent to the thorax: ~60%
The estimated pre...
Egg-on-a-string sign, also referred to as egg on its side, refers to the cardiomediastinal silhouette seen in transposition of the great arteries (TGA).
The heart appears globular due to an abnormal convexity of the right atrial border and left atrial enlargement and therefore appears like an ...
Eisenmenger complex is a specific subset of Eisenmenger syndrome, and consists of:
ventricular septal defect (VSD)
severe pulmonary arterial hypertension resulting in
shunt reversal and cyanosis
The Elliott et al. classification system of cardiomyopathies is one of the cardiomyopathy classification systems. This was published by the European Society of Cardiology Working Group on Myocardial and Pericardial Diseases. This places emphasis on phenotypic classification 1-2.
Endocardial fibroelastosis (EFE) is a rare cardiac condition which is classically described in the paediatric population (typically first two years). It is one of the causes for infants to present with unexplained heart failure.
The condition results from increasing amounts of fibro...
Endomyocardial fibrosis (EMF) is an idiopathic disorder characterised by the development of restrictive cardiomyopathy.
It usually occurs in tropical and subtropical regions of the world.There may be a greater predilection in children and adolescents.
It can occur ...
An enlarged/dilated azygos vein may result from a number of physiological as well as pathological causes. The enlarged azygos vein may be seen as a widened right paratracheal/paraspinal stripe on a frontal chest radiograph.
Causes for dilatation
There are a number of physiological causes for e...
The differential of an enlarged pulmonary trunk/main pulmonary artery on chest radiography includes:
may appear prominent in young patients especially women
rotation of the heart
left lower lobe collapse
pulmonary arterial hyp...
Eosinophilic endocarditis (or Loeffler endocarditis) is one of the cardiac manifestations of idiopathic hypereosinophilic syndrome. It also considered a form of cardiomyopathy.
It has a variable prognosis but can sometimes be fatal 4.
History and etymology
It is named after Wilhelm...
Epicardial (pericardial) fat pads are normal structures that lie in the cardiophrenic angle, more so on the right. Unsurprisingly, they are more prominent in obese patients.
They can be affected by fat necrosis (see: epipericardial fat necrosis).
Epicardial lipomatosis or epicaridal lipomatous hypertrophy is a form of cardiac lipomatosis and is characterised by accumulation of non-encapsulated mature adipose tissue in the epicardial space due to hyperplasia of lipocytes. Its exact aetiology is not well known, but it may be associated wit...
Epicardial pacing wires allow rapid commencement of atrial and/or ventricular pacing in the event of a perioperative cardiac arrhythmia that has the potential to cause significant haemodynamic compromise.
They are usually inserted during open heart surgery, and especially in those with congenit...
The Eustachian valve (also known as the "valve of the inferior vena cava") is a ridge of variable thickness in the inferior right atrium. It is a remnant of a fetal structure that directed incoming oxygenated blood to the foramen ovale and away from the right atrium.
Incomplete regression of ...
Fetal atrial fibrillation is a type of fetal tachyarrhythmia and usually has atrial rate of 400 beat per minute and a completely irregular ventricular rhythm.
Antanatal ultrasound - echocardiography
The artial contractions are usually too faint to be detected by M Mode ...
Fetal atrial flutter is the second most common fetal tachyarrhythmia and can account for up to 30% of such cases 1,2.
As with other tachyarrthymias it is often detected in the 3rd trimester.
It has a typical atrial rate of 300-600 beats per minute (bpm)...
Fetal bradyarrhythmia refers to an abnormally low fetal heart rate (less than 100-110 beats per minute 3,7) as well as being irregular, i.e. irregular fetal bradycardia.
A fetal bradyarrhythmia can fall into several types which include
fetal partial atrioventricular block (PAVB)
Fetal bradycardia refers to an abnormally low fetal heart rate, a potentially ominous finding. A sustained first trimester heart rate below 100 beats per minute (bpm) is generally considered bradycardic. The average fetal heart rate changes during pregnancy, however, and some consider the lower ...
Fetal cardiac tumours refer to primary cardiac tumours that can present in the in utero population.
Fetal cardiac tumours are rare; the prevalence, reported from autopsy studies of patients of all ages, varies from 0.0017-0.28 % 2.
Known cardiac tumour types that pres...
Fetal cardiomegaly (FC) refers to an enlarged fetal heart. It is variably defined with some sources stating the cut-off as a fetal cardio-thoracic circumference above two standard deviations 7.
It can arise from a number of situations which include
congenital cardiac anomalies: par...
Fetal cardiomyopathy refers to a very rare situation where a cardiomyopathy occurs in utero. It is often a diagnosis of exclusion where, by definition, there is an absence of an underlying congenital cardiac morphological anomaly.
The estimated incidence is variable with the high ...
Fetal cardiothoracic (C/T) circumference ratio is a parameter than can be used in assessment of fetal cardiac and thoracic/chest wall anomalies. It is the ratio of the cardiac circumference to the thoracic circumference and may be easily measured on fetal ultrasound/echocardiography.
Fetal congenital complete heart block (CAVB) is a rare cardiac conduction abnormality which is associated with high morbidity and mortality. It is considered the commonest of fetal bradyarrhymias.
The estimated prevalence of complete heart block in newborns is at ~1 in 20,000.
A standard fetal echocardiogram consists of several specific views which can be obtained to optimise visualisation of different structures and anomalies. They include:
abdominal situs view
four chamber view
left ventricular outflow tract view (or a five-chamber view)
Fetal pericardial effusions (FPE) occur when there is an accumulation of pericardial fluid in utero. In order to be considered as abnormal, it is generally accepted that the pericardial fluid thickness should be greater than 2 mm.
The estimated incidence is at ~ 2% of pregnancies ...
Fetal pericardial teratomas are rare pericardial teratomas that present in utero. They are an uncommon primary cardiac tumour occurring in a fetus.
It is a type of germ cell tumour and arises from pluripotent cells derived from all three germinal layers. In contrast to ovarian terato...
Fetal premature atrial contractions (FPAC's) are a type of extrasystoles that can be occasionally detected in fetal heart monitoring. They along with fetal premature ventricular contractions (PVC's) account for the majority of in utero rhythm disturbances 3.
They may arise from...
Fetal premature ventricular contractions (FPVC) are a type ectopic ventricular contractions detected in utero. They are a type of extrasystoles.
Premature ventricular contractions are often followed by a compensatory pause due to the refractory state of the conduction system; the next conducted...
Fetal right ventricular (RV) enlargement is an infrequently encountered situation in antenatal imaging.
The right ventricle is a dominant ventricle in in utero life. RV enlargement can occur with a number cardiac as well as non cardiac anomalies
hypoplastic left heart syndr...
A fetal sinus bradycardia is a sub type of fetal bradycardia where the fetal heart rate is abnormally slow ( less than 100 beat per minute) but runs at the regular rate with sinus rhythm.
congenital long QT syndrome 1
maternal anti Ro antibodies 2-3
Fetal supraventricular tachycardia (SVT) is considered the most common type of fetal tachyarrhythmia and can accounts for 60-90% of such cases.
It has a typical ventricular rate of ~230-280 beats per minute (bpm) 1 and isoften associated with an accessory AV conduction pathway....
Fetal tachyarrhythmia refers to an irregular increase in fetal heart rate.
Depending on its exact definition, the prevalance rate is thought to be around 0.5-1% of pregnancies.
Many cases tend to be discovered in the 3rd trimester.
Fetal tachycardia is an abnormal increase in the fetal heart rate. It is variably defined as a heart rate above 160-180 beats per minute (bpm) and typically ranges between 170-220 bpm (higher rates can occur with tachyarrhythmias).
The estimated prevalence is ~0.4-1% of pregnancie...
The following lesions may resemble a figure of eight (sometimes referred to as snowman shaped):
supracardiac variety of total anomalous pulmonary venous return 1
pituitary macroadenoma with suprasellar extension 2
intraspinal neurofibroma with extraspinal extension through neural foramina
The Fontan procedure is a repair surgical strategy for congenital cardiac anomalies. It is not usually used in isolation, but in combination with other repair procedures in a staged manner in an attempt to correct the underlying cardiac pathology.
The procedure attempts to bypass the...
The foramen ovale (or ovalis) is the opening in the interatrial septum in the fetal heart that allows blood to bypass the right ventricle and non-ventilated lungs, shunted from the right atrium to the left atrium. Specifically it represents the opening between the upper and lower portions of the...
The fossa ovale (or ovalis) is the small oval depression in the interatrial septum at the site of the closed foramen ovale, which closes once fetal circulation ceases in the first few minutes of postnatal life. It represents the overlapping primary and secondary septa of the interatrial septum. ...
The four chamber cardiac view is an important and routinely performed view in both fetal echocardiography as well as on a standard second trimester anatomy scan.
The four chamber view can only detect some of the congenital cardiac anomalies (~64% according to one study 2) ...
Fractional flow reserve (FFR) is a technique to evaluate the haemodynamic relevance of coronary artery stenoses 1,2,. It is defined as "the ratio of maximal flow achievable in the stenotic coronary artery to the maximal flow achievable in the same coronary artery if it was normal" 1 .
FFR has b...
The Gerbode defect describes a rare abnormal left-to-right shunt between the left ventricle and right atrium through a defect in the atrioventricular septum, usually congenital in aetiology.
Gerbode defects are rare congenital cardiac anomalies, and are thought to account for less...
The Glenn shunt, also known as Glenn procedure, is a palliative surgical procedure for a variety of cyanotic congenital heart diseases.
In this procedure, the systemic venous return is re-directed to the pulmonary circulation, bypassing the right heart 1-3.
It can be used in a varie...
The great cardiac vein (GCV) runs in the anterior interventricular groove and drains the anterior aspect of the heart where it is the venous complement of the left anterior descending artery. It is the main tributary of the coronary sinus.
It begins on the anterior surface of th...
Cardiac involvement in haemochromatosis typically occurs with primary haemochromatosis, as the organ is usually spared in the secondary form of the disease.
For a general discussion, and for links to other system specific manifestations, please refer to the article on haemochromatosis.
Haemopericardium refers to the presence of blood within the pericardial cavity, i.e. a sanguineous pericardial effusion. If enough blood enters the pericardial cavity, then a potentially fatal cardiac tamponade can occur.
There is a very long list of causes 1,4 but some o...
The heart is a hollow, muscular organ of the middle mediastinum, designed to pump oxygenated blood around the systemic circulation and de-oxygenated blood around the pulmonary circulation
The heart has a somewhat conical form and is enclosed by pericardium. It is positioned poste...