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.

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.

There are several potential challenges associated with routine screening for HCM in the United States. First, the U.S. athlete population of 15 million is almost twice as large as Italy's estimated athlete population. Second, these events are rare, with fewer than 100 deaths in the U.S. due to HCM in competitive athletes per year, or about 1 death per 220,000 athletes. Lastly, genetic testing would provide a definitive diagnosis; however, due to the numerous HCM-causing mutations, this method of screening is complex and is not cost-effective. Therefore, genetic testing in the United States is limited to individuals who exhibit clear symptoms of HCM, and their family members. This ensures that the test is not wasted on detecting other causes of ventricular hypertrophy (due to its low sensitivity), and that family members of the individual are educated on the potential risk of being carriers of the mutant gene(s).

An acyanotic heart defect, also known as non-cyanotic heart defect, is a class of congenital heart defects. In these, blood is shunted (flows) from the left side of the heart to the right side of the heart due to a structural defect (hole) in the interventricular septum. People often retain normal levels of oxyhemoglobin saturation in systemic circulation.

This term is outdated, because a person with an acyanotic heart defect may show cyanosis (turn blue due to insufficient oxygen in the blood).

Left to right shunting heart defects include:

- Ventricular septal defect (VSD) (30% of all congenital heart defects)

- Atrial septal defect (ASD)

- Atrioventricular septal defect (AVSD)

- Patent ductus arteriosus (PDA)

- Previously, Patent ductus arteriosus (PDA) was listed as acyanotic but in actuality it can be cyanotic due to pulmonary hypertension resulting from the high pressure aorta pumping blood into the pulmonary trunk, which then results in damage to the lungs which can then result in pulmonary hypertension as well as shunting of blood back to the right ventricle. This consequently results in less oxygenation of blood due to alveolar damage as well as oxygenated blood shunting back to the right side of the heart, not allowing the oxygenated blood to pass through the pulmonary vein and back to the left atrium.

- (Edit - this is called Eisenmenger's syndrome and can occur with Atrial septal defect and ventricular septal defect as well (actually more common in ASD and VSD) therefore PDA can still be listed as acyanotic as, acutely, it is)

Others:

- levo-Transposition of the great arteries (l-TGA)

Acyanotic heart defects without shunting include:

- Pulmonary stenosis (a narrowing of the pulmonary valve)

- Aortic stenosis

- Coarctation of the aorta

Canadian genetic testing guidelines and recommendations for individuals diagnosed with HCM are as follows:

- The main purpose of genetic testing is for screening family members.

- According to the results, at-risk relatives may be encouraged to undergo extensive testing.

- Genetic testing is not meant for confirming a diagnosis.

- If the diagnosed individual has no relatives that are at risk, then genetic testing is not required.

- Genetic testing is not intended for risk assessment or treatment decisions.

- Evidence only supports clinical testing in predicting the progression and risk of developing complications of HCM.

For individuals "suspected" of having HCM:

- Genetic testing is not recommended for determining other causes of left ventricular hypertrophy (such as "athlete's heart", hypertension, and cardiac amyloidosis).

- HCM may be differentiated from other hypertrophy-causing conditions using clinical history and clinical testing.

There are numerous types, differentiated by the extent of the defect. These types are:

- Type I: simple defects leading to communication between the ascending aorta and pulmonic trunk

- Type II: defects that extend to the origin of the right pulmonary artery

- Type III: anomalous origin of the right pulmonary artery from the ascending aorta

It is also classified as simple or complex. Simple defects are those that do not require surgical repair, occur with no other defects, or those that require minor stright-forward repair (ductus arteriosus, atrial septal defect). Complex defects are those that occur with other anatomical anomalies or require non-standard repair.

Aortopulmonary septal defect is a rare congenital heart disorder accounting for only 0.1-0.3% of congenital heart defects worldwide. It is characterized by a communication between the aortic and pulmonary arteries, with preservation of two normal semilunar valves. It is the result of an incomplete separation of the aorticopulmonary trunk that normally occurs in early fetal development with formation of the spiral septum. Aortopulmonary septal defects occur in isolation in about half of cases, the remainder are associated with more complex heart abnormalities.

Ventricular inversion, also known as atrioventricular discordance, is a condition in which the anatomic right ventricle of the heart is on the left side of the interventricular septum and the anatomic left ventricle is on the right.

Recent studies suggest that cardiac resynchronization therapy can reduce the incidence of ventricular dyssynchrony and thus increase cardiac efficiency.

Literature survey on epidemiology and pathology of cardiac fibroma:

During this study, researchers searched through the literature databases on cardiac fibroma to find factors that predict poor outcomes that lead to death. Researchers found that patients who did not survive were significantly younger than those who did survive. These results suggest that younger individuals diagnosed with cardiac fibroma are associated with a poorer outcome. They found no significant difference between the maximum diameter of the tumor between age groups. Even though younger individuals have smaller hearts, the high ratio of tumor-to-heart sizes may generate low cardiac output, which leads to a poor outcome. Literature revealed that 18 of 178 patients with cardiac fibroma were diagnosed during prenatal and neonatal periods, resulting in the tumor having a certain size regardless of the child's age. These findings suggest that cardiac fibromas may be a congenital disorder.

Successful Surgical Excision of a Large Cardiac Fibroma in an Asymptomatic Child:

A 3-year-old girl, who was asymptomatic, underwent a successful surgical excision of a large cardiac fibroma. She had frequent coughs, which led to a chest radiograph. A cardiac mass was found on the echocardiography and later was confirmed by magnetic resonance imaging (MRI). After 24 hours of being monitored, it showed sinus rhythms of normal variability. The mass dimensions were 38 X 28 mm in the apical area of the left ventricle. A surgical procedure was recommended due to the risk of ventricular arrhythmias and sudden cardiac death. The surgery was a success and they were able to remove the entire tumor without any complications. Follow-up evaluations at six-months and a year showed the patient was in good health and no signs of tumor recurrence. Asymptomatic patients with cardiac fibroma becomes controversial because these tumors have the tendency to grow. Situations like this, a surgical removal will be the top recommendation for patients.

Primary cardiac tumors in children: a center's experience:

The Department of Cardiac Surgery Children's Hospital in China conducted a study to analyze different characteristics and outcomes of pediatric patients who have primary cardiac tumors treated in their center. They had sixteen patients with primary cardiac tumors between the ages of 1–13 years. All patients were diagnosed by echocardiography, MRI, and computed tomography (CT). As a result, they were able to successfully remove the mass from 15 patients with cardiopulmonary bypass, whereas partial resection was done in one patient. Unfortunately, one patient died during surgery due to low cardiac output syndrome at 5 days after operation. The pathological examination of the cardiac masses showed that rhabdomyoma is the most frequent tumor in children, followed by myxoma, fibromas, etc. Morbidity of rhabdomyomas and fibromas were reported higher in infancy, while myxomas are more frequent in older children.

In cardiology, Ventricular dyssynchrony is a difference in the timing, or lack of synchrony, of contractions in different ventricles in the heart. Large differences in timing of contractions can reduce cardiac efficiency and is correlated with heart failure.

The cause of development for cardiac fibroma is still unknown or unexplained. Some of these cases are observed to be linked to Gorlin syndrome; a complex genetic disorder causing the formation of tumors in various parts of the body. Research is currently being undertaken to identify relevant casual factors. Currently, there are no known methods for preventing cardiac fibroma.

The most common cause of myocardial rupture is a recent myocardial infarction, with the rupture typically occurring three to five days after infarction. Other causes of rupture include cardiac trauma, endocarditis (infection of the heart), cardiac tumors, infiltrative diseases of the heart, and aortic dissection.

Risk factors for rupture after an acute myocardial infarction include female gender, advanced age of the individual, first ischemic event, and a low body mass index. Other presenting signs associated with myocardial rupture include a pericardial friction rub, sluggish flow in the coronary artery after it is opened i.e. revascularized with an angioplasty, the left anterior descending artery being often the cause of the acute MI, and delay of revascularization greater than 2 hours.

Parasystole is a kind of arrhythmia caused by the presence and function of a secondary pacemaker in the heart, which works in parallel with the SA node. Parasystolic pacemakers are protected from depolarization by the SA node by some kind of "entrance block". This block can be complete or incomplete.

Parasystolic pacemakers can exist in both the atrium or the ventricle. Atrial parasystolia are characterized by narrow QRS complexes

Two forms of ventricular parasystole have been described in the literature, fixed parasystole and modulated parasystole. Fixed ventricular parasystole occurs when an ectopic pacemaker is protected by entrance block, and thus its activity is completely independent from the sinus pacemaker activity. Hence, the ectopic pacemaker is expected to fire at a fixed rate.

Therefore, on ECG, the coupling intervals of the manifest ectopic beats will wander through the basic cycle of the sinus rhythm. Accordingly, the traditional electrocardiographic criteria used to recognize the fixed form of parasystole are:

- the presence of variable coupling intervals of the manifest ectopic beats;

- inter-ectopic intervals that are simple multiples of a common denominator;

- fusion beats.

According to the modulated parasystole hypothesis, rigid constancy of a pacemaker might be expected if the entrance block were complete, but if there is an escape route available for the emergence of ectopic activity, then clearly there must be an effective ionic communication, not complete insulation, between the two tissues. If there is an electrical

communication between the two, then the depolarization of the surrounding ventricle may influence the ectopic pacemaker. That influence will be electrotonic; depolarization of the surrounding field will induce a partial depolarization

of the pacemaker cells. Therefore, appropriate diagnosis of modulated parasystole relies upon the construction of a “phase response curve” as theoretical evidence of modulation of the ectopic pacemaker cycle length by the electrotonic activity generated by the sinus discharges across the area of protection. In this case, the timing of the arrival of the electronic stimulus will serve to delay or advance the subsequent pacemaker activation. In this case, the coupling intervals between the manifest ectopic and sinus discharges will be either fixed or variable, depending on the cycle length relations between the two pacemakers.

The frequency of tamponade is unclear. One estimate from the United States places it at 2 per 10,000 per year. It is estimated to occur in 2% of those with stab or gunshot wounds to the chest.

Cardiogenic shock is caused by the failure of the heart to pump effectively. It can be due to damage to the heart muscle, most often from a large myocardial infarction. Other causes include abnormal heart rhythms, cardiomyopathy, heart valve problems, ventricular outflow obstruction (i.e. aortic valve stenosis, aortic dissection, cardiac tamponade, constrictive pericarditis, systolic anterior motion (SAM) in hypertrophic cardiomyopathy), or ventriculoseptal defects.

It can also be caused by a sudden decompressurization (e.g. in an aircraft), where air bubbles are released into the bloodstream (Henry's Law), causing heart failure.

The incidence of myocardial rupture has decreased in the era of urgent revascularization and aggressive pharmacological therapy for the treatment of an acute myocardial infarction. However, the decrease in the incidence of myocardial rupture is not uniform; there is a slight increase in the incidence of rupture if thrombolytic agents are used to abort a myocardial infarction. On the other hand, if primary percutaneous coronary intervention is performed to abort the infarction, the incidence of rupture is significantly lowered. The incidence of myocardial rupture if PCI is performed in the setting of an acute myocardial infarction is about 1 percent.

Cardiac tamponade is caused by a large or uncontrolled pericardial effusion, i.e. the buildup of fluid inside the pericardium. This commonly occurs as a result of chest trauma (both blunt and penetrating), but can also be caused by myocardial rupture, cancer, uremia, pericarditis, or cardiac surgery, and rarely occurs during retrograde aortic dissection, or while the person is taking anticoagulant therapy. The effusion can occur rapidly (as in the case of trauma or myocardial rupture), or over a more gradual period of time (as in cancer). The fluid involved is often blood, but pus is also found in some circumstances.

Causes of increased pericardial effusion include hypothyroidism, physical trauma (either penetrating trauma involving the pericardium or blunt chest trauma), pericarditis (inflammation of the pericardium), iatrogenic trauma (during an invasive procedure), and myocardial rupture.

Cardiogenic shock is a life-threatening medical condition resulting from an inadequate circulation of blood due to primary failure of the ventricles of the heart to function effectively. Signs of inadequate blood flow to the body's organs include low urine production (<30 mL/hour), cool arms and legs, and altered level of consciousness. It may lead to cardiac arrest, which is an abrupt stopping of cardiac pump function.

As this is a type of circulatory shock, there is insufficient blood flow and oxygen supply for biological tissues to meet the metabolic demands for oxygen and nutrients. Cardiogenic shock is defined by sustained low blood pressure with tissue hypoperfusion despite adequate left ventricular filling pressure.

Treatment of cardiogenic shock depends on the cause. If cardiogenic shock is due to a heart attack, attempts to open the heart's arteries may help. An intra-aortic balloon pump or left ventricular assist device may improve matters until this can be done. Medications that improve the heart's ability to contract (positive inotropes) may help; however, it is unclear which is best. Norepinephrine may be better if the blood pressure is very low whereas dopamine or dobutamine may be more useful if only slightly low. Cardiogenic shock is a condition that is difficult to fully reverse even with an early diagnosis. With that being said, early initiation of mechanical circulatory support, early percutaneous coronary intervention, inotropes, and heart transplantation may improved outcomes.

Constrictive pericarditis is a medical condition characterized by a thickened, fibrotic pericardium, limiting the heart's ability to function normally. In many cases, the condition continues to be difficult to diagnose and therefore benefits from a good understanding of the underlying cause.

The cause of constrictive pericarditis in the developing world are idiopathic in origin, though likely infectious in nature. In regions where tuberculosis is common, it is the cause in a large portion of cases.

Causes of constrictive pericarditis include:

- Tuberculosis

- Incomplete drainage of purulent pericarditis

- Fungal and parasitic infections

- Chronic pericarditis

- Postviral pericarditis

- Postsurgical

- Following MI, post-myocardial infarction

- In association with pulmonary asbestos

3C syndrome is very rare, occurring in less than 1 birth per million. Because of consanguinity due to a founder effect, it is much more common in a remote First Nations village in Manitoba, where 1 in 9 people carries the recessive gene.

The surgical treatment involves the resection of the extracranial venous package and ligation of the emissary communicating vein. In some cases of SP, surgical excision is performed for cosmetic reasons. The endovascular technique has been described by transvenous approach combined with direct puncture and the recently endovascular embolization with Onyx.

Sinus pericranii is a venous anomaly where a communication between the intracranial dural sinuses and dilated epicranial venous structures exists. That venous anomaly is a collection of nonmuscular venous blood vessels adhering tightly to the outer surface of the skull and directly communicating with intracranial venous sinuses through diploic veins. The venous collections receive blood from and drain into the intracranial venous sinuses. The varicosities are intimately associated with the periostium, are distensible, and vary in size when changes in intracranial pressure occur.