VSDs are the most common congenital cardiac abnormalities. They are found in 30-60% of all newborns with a congenital heart defect, or about 2-6 per 1000 births. During heart formation, when the heart begins life as a hollow tube, it begins to partition, forming septa. If this does not occur properly it can lead to an opening being left within the ventricular septum. It is debatable whether all those defects are true heart defects, or if some of them are normal phenomena, since most of the trabecular VSDs close spontaneously. Prospective studies give a prevalence of 2-5 per 100 births of trabecular VSDs that close shortly after birth in 80-90% of the cases.

Hypertension is defined when a patient's blood pressure in the arm exceeds 140/90 mmHg under normal conditions. This is a severe problem for the heart and can cause many other complications. In a study of 120 coarctation repair recipients done in Groningen, The Netherlands, twenty-nine patients (25%) experienced hypertension in the later years of life due to the repair. While hypertension has many different factors that lead to this stage of blood pressure, people who have had a coarctation repair — regardless of the age at which the operation was performed — are at much higher risk than the general public of hypertension later in life. Undetected chronic hypertension can lead to sudden death among coarctation repair patients, at higher rates as time progresses.

Angioplasty is a procedure done to dilate an abnormally narrow section of a blood vessel to allow better blood flow. This is done in a cardiac catheterization laboratory. Typically taking two to three hours, the procedure may take longer but usually patients are able to leave the hospital the same day. After a coarctation repair 20-60% of infant patients may experience reoccurring stenosis at the site of the original operation. This can be fixed by either another coarctectomy.

Coronary artery disease (CAD) is a major issue for patients who have undergone a coarctation repair. Many years after the procedure is done, heart disease not only has an increased chance of affecting coarctation patients, but also progresses through the levels of severity at an alarmingly increased rate. In a study conducted by Mare Cohen, MD, et al., one fourth of the patients who experienced a coarctation died of heart disease, some at a relatively young age.

Clinical criteria are used in most studies when defining recurrence of coarctation (recoarctation) when blood pressure is at a difference of >20 mmHg between the lower and upper limbs. This procedure is most common in infant patients and is uncommon in adult patients. In a study conducted by Koller et al., 10.8% of infant patients underwent recoarctations at less than two years of age while another 3.1% of older children received a recoarctation.

People who have had a coarctation of the aorta are likely to have bicuspid aortic valve disease. Between 20% and 85% of patients are affected with this disease. Bicuspid aortic valve disease is a big contributor to cardiac failure, which in turn makes up roughly 20% of late deaths to coarctation patients.

Leaving the hospital after a coarctation procedure is only one step in a lifelong process. Just because the coarctation was fixed does not mean that the patient is cured. It is extremely important to visit the cardiologist on a regular basis. Depending on the severity of the patient's condition, which is evaluated on a case-by-case level, visiting a cardiologist can be a once a year surveillance check up. Keeping a regular schedule of appointments with a cardiologist after a coarctation procedure is complete helps increase the chances of survivability for the patients.

Congenital VSDs are frequently associated with other congenital conditions, such as Down syndrome.

A VSD can also form a few days after a myocardial infarction (heart attack) due to mechanical tearing of the septal wall, before scar tissue forms, when macrophages start remodeling the dead heart tissue.

The causes of congenital VSD (ventricular septal defect) include the

incomplete looping of the heart during days 24-28 of development. Faults with NKX2.5 gene are usually associated with isolated (non syndromic) ASD in humans when one copy is missing.

Vein of Galen malformations are devastating complications. Studies have shown that 77% of untreated cases result in mortality. Even after surgical treatment, the mortality rate remains as high as 39.4%. Most cases occur during infancy when the mortality rates are at their highest. Vein of Galen malformations are a relatively unknown affliction, attributed to the rareness of the malformations. Therefore, when a child is diagnosed with a faulty Great Cerebral Vein of Galen, most parents know little to nothing about what they are dealing with. To counteract this, support sites have been created which offer information, advice, and a community of support to the afflicted (, ).

Taussig–Bing syndrome (after Helen B. Taussig and Richard Bing) is a cyanotic congenital heart defect in which the patient has both double outlet right ventricle (DORV) and subpulmonic ventricular septal defect (VSD).

In DORV, instead of the normal situation where blood from the left ventricle (LV) flows out to the aorta and blood from the right ventricle (RV) flows out to the pulmonary artery, both aorta and pulmonary artery are connected to the RV, and the only path for blood from the LV is across the VSD. When the VSD is subpulmonic (sitting just below the pulmonary artery), the LV blood then flows preferentially to the pulmonary artery. Then the RV blood, by default, flows mainly to the aorta.

The clinical manifestations of a Taussig-Bing anomaly, therefore, are much like those of dextro-Transposition of the great arteries (but the surgical repair is different). It can be corrected surgically also with the arterial switch operation (ASO).

It is managed with Rastelli procedure.

The complications that are usually associated with vein of Galen malformations are usually intracranial hemorrhages. Over half the patients with VGAM have a malformation that cannot be corrected. Patients frequently die in the neonatal period or in early infancy.

The Canadian Cardiovascular Society (CCS) recommends surgical intervention for these indications:

- Limited exercise capacity (NYHA III-IV)

- Increasing heart size (cardiothoracic ratio greater than 65%)

- Important cyanosis (resting oxygen saturation less than 90% - level B)

- Severe tricuspid regurgitation with symptoms

- Transient ischemic attack or stroke

The CCS further recommends patients who require operation for Ebstein's anomaly should be operated on by congenital heart surgeons who have substantial specific experience and success with this operation. Every effort should be made to preserve the native tricuspid valve.

Ebstein's cardiophysiology typically presents as an (antidromic) AV reentrant tachycardia with associated pre-excitation. In this setting, the preferred medication treatment agent is procainamide. Since AV-blockade may promote conduction over the accessory pathway, drugs such as beta blockers, calcium channel blockers, and digoxin are contraindicated.

If atrial fibrillation with pre-excitation occurs, treatment options include procainamide, flecainide, propafenone, dofetilide, and ibutilide, since these medications slow conduction in the accessory pathway causing the tachycardia and should be administered before considering electrical cardioversion. Intravenous amiodarone may also convert atrial fibrillation and/or slow the ventricular response.

Passage of a clot (thrombus) from a systemic vein to a systemic artery. When clots in systemic veins break off (embolize), they travel first to the right side of the heart and, normally, then to the lungs where they lodge, causing pulmonary embolism. On the other hand, when there is a hole at the septum, either upper chambers of the heart (an atrial septal defect) or lower chambers of the heart (ventricular septal defects), a clot can cross from the right to the left side of the heart, then pass into the systemic arteries as a paradoxical embolism. Once in the arterial circulation, a clot can travel to the brain, block a vessel there, and cause a stroke (cerebrovascular accident).

Risk factors for thromboembolism, the major cause of arterial embolism, include disturbed blood flow (such as in atrial fibrillation and mitral stenosis), injury or damage to an artery wall, and hypercoagulability (such as increased platelet count). Mitral stenosis poses a high risk of forming emboli which may travel to the brain and cause stroke. Endocarditis increases the risk for thromboembolism, by a mixture of the factors above.

Atherosclerosis in the aorta and other large blood vessels is a common risk factor, both for thromboembolism and cholesterol embolism. The legs and feet are major impact sites for these types. Thus, risk factors for atherosclerosis are risk factors for arterial embolisation as well:

- advanced age

- cigarette smoking

- hypertension (high blood pressure)

- obesity

- hyperlipidemia, e.g. hypercholesterolemia, hypertriglyceridemia, elevated lipoprotein (a) or apolipoprotein B, or decreased levels of HDL cholesterol)

- diabetes mellitus

- Sedentary lifestyle

- stress

Other important risk factors for arterial embolism include:

- recent surgery (both for thromboembolism and air embolism)

- previous stroke or cardiovascular disease

- a history of long-term intravenous therapy (for air embolism)

- Bone fracture (for fat embolism)

A septal defect of the heart makes it possible for paradoxical embolization, which happens when a clot in a vein enters the right side of the heart and passes through a hole into the left side. The clot can then move to an artery and cause arterial embolisation.

A paradoxical embolism, also called a crossed embolism, refers to an embolus which is carried from the venous side of circulation to the arterial side, or vice versa. It is a kind of stroke or other form of arterial thrombosis caused by embolism of a thrombus (blood clot), air, tumor, fat, or amniotic fluid of venous origin, which travels to the arterial side through a lateral opening in the heart, such as a patent foramen ovale, or arteriovenous shunts in the lungs.

The opening is typically an atrial septal defect, but can also be a ventricular septal defect.

Paradoxical embolisms represent two percent of arterial emboli.

In a newborn boy thought to have Fryns syndrome, Clark and Fenner-Gonzales (1989) found mosaicism for a tandem duplication of 1q24-q31.2. They suggested that the gene for this disorder is located in that region. However, de Jong et al. (1989), Krassikoff and Sekhon (1990), and Dean et al. (1991) found possible Fryns syndrome associated with anomalies of chromosome 15, chromosome 6, chromosome 8(human)and chromosome 22, respectively. Thus, these cases may all represent mimics of the mendelian syndrome and have no significance as to the location of the gene for the recessive disorder.

By array CGH, Slavotinek et al. (2005) screened patients with DIH and additional phenotypic anomalies consistent with Fryns syndrome for cryptic chromosomal aberrations. They identified submicroscopic chromosome deletions in 3 probands who had previously been diagnosed with Fryns syndrome and had normal karyotyping with G-banded chromosome analysis. Two female infants were found to have microdeletions involving 15q26.2 (see 142340), and 1 male infant had a deletion in band 8p23.1 (see 222400).

In France, Aymé, "et al." (1989) estimated the prevalence of Fryns syndrome to be 0.7 per 10,000 births based on the diagnosis of 6 cases in a series of 112,276 consecutive births (live births and perinatal deaths).

While most cases of horseshoe kidneys are asymptomatic and discovered upon autopsy, the condition may increase the risk for:

- Kidney obstruction – abnormal placement of ureter may lead to obstruction and dilation of the kidney.

- Kidney infections – associated with vesicoureteral reflux.

- Kidney stones – deviant orientation of kidneys combined with slow urine flow and kidney obstruction may lead to kidney stones.

- Kidney cancer – increased risk of renal cancer, especially Wilms' tumor, transitional cell carcinoma, and an occasional case report of carcinoid tumor. Despite increased risk, the overall risk is still relatively low.

The prevalence of horseshoe kidneys in females with Turner Syndrome is about 15%.

It can be associated with trisomy 18.

It can be associated with venous anomalies like left sided IVC 9.

Pancreas divisum in individuals with no symptoms does not require treatment. Treatment of those with symptoms varies and has not been well established. A surgeon may attempt a sphincterotomy by cutting the minor papilla to enlarge the opening and allow pancreatic enzymes to flow normally. During surgery, a stent may be inserted into the duct to ensure that the duct will not close causing a blockage. This surgery can cause pancreatitis in patients, or in rare cases, kidney failure and death.

An association with adenoma of the minor papilla has been reported.

Arterial embolisms can consist of various materials, including:

- Thromboembolism – embolism of thrombus or blood clot.

- Cholesterol embolism - embolism of cholesterol, often from atherosclerotic plaque inside a vessel.

- Fat embolism – embolism of bone fracture or fat droplets.

- Air embolism (also known as a gas embolism) – embolism of air bubbles.

- Septic embolism – embolism of pus containing bacteria.

- "Cancer embolism"

In contrast, amniotic fluid embolism almost exclusively affects the venous side.

Omphalomesenteric duct cysts (ODC, also known as an omphalomesenteric duct remnant or vitelline cyst) are developmental defects relating to the closure of the omphalomesenteric duct. It usually disintegrates within six weeks of gestation, but remnants of the cyst can sometimes be found along the intestines or umbilicus. Any remnants can be removed via surgical means.

A majority of individuals born with pancreas divisum will not have symptoms. In some cases, pancreas divisum is only detected during autopsy. A small group of individuals will develop symptoms which commonly include abdominal pain, nausea, vomiting, and acute and chronic pancreatitis.

In 2008 researchers found autosomal dominant mutations in the RET and GDNF genes to be linked to renal agenesis in unrelated stillborn fetuses through PCR and direct sequence analysis . In the study, DNA from 33 stillborn fetuses were sequenced for mutations in RET, GDNF and GFRA1. Nineteen of the fetuses had BRA, ten had URA and 4 had congenital renal dysplasia. Seven of the 19 BRA fetuses were found to have a mutation in the RET gene (37%), while two of the ten URA fetuses did (20%). One of the URA fetuses had two RET mutations and one GDNF mutation. There were no GFRA1 mutations found.

However, the results of Skinner et al. study were questioned by a more recent study with a larger number of cases . In this study 105 fetuses were analyzed. Sixty-five fetuses had BRA while 24 had URA with an abnormal contralateral kidney. Mutations in the RET gene were only found in seven of the fetuses (6.6%).

In 2014 researchers found autosomal recessive mutations in ITGA8 in three members of two unrelated families utilizing Exome Sequencing . One of the families was consanguineous.

In 2017 researchers identified heritable autosomal dominant mutations in the gene GREB1L in two unrelated families as being the cause of both BRA and URA utilizing Exome Sequencing and direct sequencing analysis . This is the first reported genetic lesion implicated in the activation of Retinoic Acid Receptor (RAR) Targets that has been associated with renal agenesis in humans. The researchers found two different GREB1L mutations, each being unique to their respective pedigrees. In total, there were 23 individuals analyzed between the two families, four of which had BRA and five of which had URA. GREB1L mutations were identified in all of the affected individuals as well as in three unaffected family members, demonstrating incomplete penetrance and variable expressivity.

There are several hundred to perhaps several thousand genes that, if they had the right kind of mutation, could lead to renal agenesis in humans. It is possible that each individual or family experiencing renal agenesis has a unique gene or genetic mutation causing the condition due to the fact that there are so many genes that are critical to proper renal development. See Rosenblum S et al. for an excellent review of Congenital abnormalities of the Kidney and Urinary Tract

Chromosomal anomalies have been associated with BRA in certain cases (chromosomes 1, 2, 5 and 21), but these anomalies were not inherited and have not been observed in subsequent cases. Additionally, neither extreme substance abuse or environmental factors (high power line, mercury, ground water issues, etc.) have been reported to be linked to an increased incidence of BRA or other cause of Potter sequence. However, renal agenesis and other causes of oligohydramnios sequence have been linked to a number of other conditions and syndromes to include Down syndrome, Kallmann syndrome, branchio-oto-renal syndrome and others.

This is much more common, but is not usually of any major health consequence, as long as the other kidney is healthy.

It may be associated with an increased incidence of Müllerian duct abnormalities, which are abnormalities of the development of the female reproductive tract and can be a cause of infertility, blocked menstrual flow (hematocolpos), increased need for Caesarean sections, or other problems. Herlyn-Werner-Wunderlich syndrome is one such syndrome in which unilaterial renal agenesis is combined with a blind hemivagina and uterus didelphys. Up to 40% of women with a urogenital tract anomaly also have an associated renal tract anomaly.

Adults with unilateral renal agenesis have considerably higher chances of hypertension (high blood pressure). People with this condition are advised to approach contact sports with caution.

The odds of a person being born with unilateral renal agenesis are approximately 1 in 750.

Horseshoe kidney, also known as "ren arcuatus" (in Latin), renal fusion or super kidney, is a congenital disorder affecting about 1 in 600 people, more common in men.

In this disorder, the patient's kidneys fuse together to form a horseshoe-shape during development in the womb. The fused part is the isthmus of the horseshoe kidney.

Fusion abnormalities of the kidney can be categorized into two groups: horseshoe kidney and crossed fused ectopia. The 'horseshoe kidney' is the most common renal fusion anomaly.

Hepatic microvascular dysplasia (HMD or MVD) or portal atresia is a disorder where mixing of venous blood and arterial blood in the liver occurs at the microscopic level. It occurs most commonly in certain dog breeds such as the Cairn and Yorkshire terriers although any dog breed may be at risk.

This disease may also be found in cats.

HMD is sometimes misdiagnosed as Portosystemic vascular anomaly (PSVA) or a "Liver Shunt" (portosystemic shunt). HMD can be diagnosed with an MRI, using a tracing dye in the subject's blood, and observing the flow of blood through the subject's liver and surrounding areas (stomach, intestine) for anomalies. It can also be diagnosed using a bile-acid level test; or more accurately, a "fasting-blood ammonia levels" test. Symptoms include stunted growth in the first 6–9 months, vomiting, seizures, and hydro-encephalitic episodes (from ammonia concentrating in the blood). HMD is usually treated non-surgically with antibiotics (metronidazole) and stool-softeners (lactulose).

Anterior segment mesenchymal dysgenesis is a failure of the normal development of the tissues of the anterior segment of the eye. It leads to anomalies in the structure of the mature anterior segment, associated with an increased risk of glaucoma and corneal opacity.

Peters' (frequently misspelled Peter's) anomaly is a specific type of mesenchymal anterior segment dysgenesis, in which there is central corneal leukoma, adhesions of the iris and cornea, and abnormalities of the posterior corneal stroma, Descemet's membrane, corneal endothelium, lens, and anterior chamber.

The outcome of Potter's Sequence is poor. A series of 23 patients in 2007 recorded 7 deaths, 4 in the neonatal period. All 16 survivors have chronic kidney disease, with half developing end stage renal failure (median age 0.3 years, range 2 days to 8.3 years). Survivors had growth impairment (44%) and cognitive and motor development delay (25%)

The first child to survive Bilateral Renal Agenesis (BRA), Abigail Rose Herrera Beutler, was born on July 2013 to US Congresswoman Jaime Herrera Beutler.

A few weeks before she was born, Dr. Jessica Bienstock, a professor of maternal-fetal medicine at Johns Hopkins Hospital, administered a series of saline solution injections into the mother's womb to help the baby's lungs to develop. After Abigail was born, the procedure was considered a success. The infant did not need artificial respiration and could breathe on her own. Her parents kept her on kidney dialysis at home until old enough for a kidney transplant. On February 8, 2016, at the age of two, Abigail received a kidney from her father at the Lucile Packard Children's Hospital Stanford in California.