Congenital Heart Disease - DrCRaghu

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Patent ductus arteriosus (PDA) is a congenital heart condition in which there is an opening between the pulmonary artery and the aorta. The ductus arteriosus is a small connection in the fetal heart helps oxygen rich blood to by-pass the immature baby’s lungs and flow into the body. This connection naturally closes shortly after birth. The connections that fail to close, are called patent ductus arteriosus, where the oxygen-rich and oxygen-poor combines together resulting in an increase in the workload of heart and various other complications.

It is the sixth most common type of congenital heart disease, and is frequently diagnosed in infants; although it may remain unknown until childhood or even adulthood.

Symptoms:

The symptoms depend on the size of the patent duct and the gestational age of the neonate. A small patent ductus arteriosus can remain unrecognized until adulthood, whereas, a large patent ductus arteriosus may lead to life threatening conditions such as heart failure.

In neonates, a heart murmur on auscultation during regular checkup may indicate PDA.

In infants, a large PDA would show the following symptoms:

  • Inability or difficulty in feeding, leading to poor growth
  • Sweating on crying or eating
  • Persistent fast breathing or breathlessness
  • Cough
  • Lower respiratory tract infections
  • Pneumonia
  • Easy tiring
  • Rapid heart rate

The symptoms in the case of adults with undiagnosed PAD include heart attack, atrial arrhythmia or with the occurrence of shunting of unoxygenated blood from pulmonary to systemic circulation.

Causes:

In most of the children the cause of PDA is unknown, but genetic factors were thought to play a causative role. Every baby is born with ductus arteriosus which eventually narrows and closes within three to four days after birth. It may take longer time for closure in the case of premature babies. But if the duct doesn’t close, it may lead to an increase in the blood flow to the heart and lungs of the baby, which might enlarge or weaken the heart muscle.

Risk factors:

The risk factors of having patent ductus arteriosus include:

  • Gender: PDA is more common in girls than in boys.
  • Prematurity: It is more common in babies who are born before the gestational term than in full term babies.
  • Family history: A family history of heart conditions and other genetic disorders, such as Down’s syndrome may increase the risk of PDA.
  • Rubella infection: If the mother is affected with rubella infection during pregnancy, the virus may cross the placenta and spread through the baby’s circulatory system potentially damaging blood vessels and organs including the heart.
  • High altitude birth risk: Babies born at altitudes higher than 10,000 feet are at an increased risk.
  • Congenital heart problems: Babies with congenital heart problems such as hypoplastic left heart syndrome, transposition of the great vessels, and pulmonary stenosis are at high risk

Diagnosis:

A heart murmur heard during a regular checkup may lead to further work-up for PDA.

The following tests Are recommended for diagnosis of PDA:

  • Chest X-ray to assess the condition of the heart and lungs, and also to rule out other conditions
  • Echocardiogram to assess the heart, its valves and chambers for any defects and see if the heart is pumping properly
  • Electrocardiogram (ECG) to assess the electrical activity of the heart to diagnose any heart defects or rhythm problems
  • Cardiac catheterization to rule out other congenital heart defects found during an echocardiogram or in a case where the catheter procedure is considered for the treatment

Treatment:

Treatment is generally not considered, as the PDA usually closes on its own in the case of a premature baby. Close monitoring is considered for full term babies, children and adults with small PDA and with no other health complications. During follow-up, if the baby does not have any other complications, it is considered to be closed. On the other hand, if the baby has certain heart problems or defects, the ductus arteriosus might be lifesaving.

In a premature baby, it may take one to two years. But in full term babies, PDA that remains open after several weeks rarely closes on its own.

Medicines such as indomethacin or ibuprofen may be considered. These medicines work well for some newborns. The earlier treatment is given; greater are the chances for it to succeed.

Medical procedures may be considered in the case where medications are not effective. A transcatheter procedure is used to block blood flow through the vessel. An open heart surgery might be considered if the catheter procedure is not suitable to repair PDA.

Prevention:

Patent ductus arteriosus may not be prevented, but certain measures should be observed for a healthy pregnancy.

  • Early prenatal care
  • Healthy diet
  • Regular exercise
  • Avoiding consumption of alcohol, illegal drugs and cigarettes.
  • Getting vaccinated as recommended.
  • Optimal diabetes control.

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The heart consists of four chambers, of which upper two chambers are called as atria and lower two chambers are called as ventricles. Right and left chambers are separated by a wall of muscle called a septum. Right two chambers pump the deoxygenated blood to the lungs and left two chambers pump oxygenated blood to the different parts of the body.

Ventricular septal defects (VSD) is a common type of congenital heart defect, which is characterized by an abnormal opening or a hole in interventricular septum, the dividing wall between right and left ventricles. The oxygen-rich blood from the left ventricle will enter into the right ventricle through the opening, thereby getting mixed with deoxygenated blood and then enters into lungs. This will force the heart and lungs to work harder.

Causes:

The exact cause of VSD is unknown. During fetal heart developmental stage, the heart develops from a large tube which eventually divides into chambers and walls. Any abnormality in this process will lead to the formation of a defect in the septum. If the defect is in the interventricular septum, then it is said to be ventricular septal defect. There may be one or more VSDs.

Types:

Based on the location and development of VSD, it is classified into following types:

  • Conoventricular Ventricular Septal Defect: It occurs just below the pulmonary and aortic valves.
  • Perimembranous Ventricular Septal Defect: It occurs in the upper part of the ventricular septum.
  • Inlet Ventricular Septal Defect: It occurs adjacent to the tricuspid and mitral valves. This type of defect might be associated with atrial septal defect.
  • Muscular Ventricular Septal Defect: It is the most common type of VSD, which occurs in the lower muscular part of the interventricular septum.

Signs and symptoms:

Small defects in the septum do not show any symptoms because it closes on its own gradually during childhood. Large defects shows signs and symptoms usually after birth within few days or weeks or months.

The first sign of VSD is heart murmur, which is a whooshing sound that can be heard using a stethoscope. The other symptoms include:

  • Fatigue (tiredness)
  • Arrhythmias (abnormal heart rhythm)
  • Fast breathing or breathlessness
  • Poor feeding
  • Poor weight gain
  • Pale skin
  • Enlarged liver

Risk factors:

Ventricular septal defects mostly occur due to defective genes and chromosomes, that may be hereditary. Environmental factors during pregnancy may also play a role in development of VSD in the fetus.

Complications:

Large or medium septal defects if left untreated, may lead to life threatening complications such as:

  • Heart failure, as heart need to work harder to pump enough blood to the body.
  • Pulmonary hypertension (increased blood flow to the lungs results in increased blood pressure in the lung arteries).
  • Endocarditis (infection in the endocardium of heart).
  • Other heart problems such as abnormal heart rhythms and valve problems.

Diagnosis:

If heart murmurs are detected during the physical examination, the patient may be advised further testing to conform the diagnosis.

  • Echocardiogram: This test is the primary tool for the diagnosis of VSD, as it can be used to determine the size, location and severity of the ventricular septal defect. Sound waves are used to produce the detailed images of the heart.
  • Electrocardiogram (ECG): This test records the electrical activity of the heart and helps to identify the abnormal heart rhythms and defects in the septum.
  • Chest X-ray: X-rays are used to view the images of heart and lungs. In VSD, this test helps to determine the enlarged heart and extra fluid in the lungs.
  • Cardiac catheterization: The test involves inserting a thin, flexible tube into the blood vessel at the groin or an arm, which is guided to the heart, to identify any congenital heart defects and to determine the function of the heart chambers and its valves.
  • Pulse oximetry: Oxygen levels in the blood can be measured using a small clip which is placed on the fingertip.

Treatment:

Usually treatment is not needed for small VSDs, as they close on their own gradually after birth. Babies with larger VSD need surgery to prevent any further complications. The treatment for ventricular septal defects include:

  • Medications such as diuretics like furosemide are used to reduce the amount of fluid in the blood that is pumped to the lungs and in the circulation. Beta blockers like metoprolol, propranolol and digoxin are used to maintain the regular heartbeat.
  • Surgical procedures include surgical repair, catheter procedure and hybrid procedure.
    Surgical repair involves open heart surgery, in which the doctor uses a patch or stitches to close the hole, performed under general anaesthesia.
    In catheter procedure, a catheter is inserted into a blood vessel and then passed to the heart. The defect is closed using a specially sized mesh device.
    Hybrid procedure uses both surgical repair and catheterization procedures to close the hole, with the help of a heart-lung machine and a catheter placed through an incision.

Prevention:

Ventricular septal defects cannot be prevented, but following certain measures during pregnancy may be helpful to prevent the risk of VSD. The measures include:

  • Prenatal care before pregnancy: Consult a physician before planning for pregnancy and inform him about the family history of any congenital defects and the medications using currently, so that he may give suggestions or recommend some lifestyle modifications to avoid the risk of heart defects.
  • Healthy diet: Having a balanced diet including vitamins and folic acid during pregnancy will help in giving birth to a healthy child without any heart defects.
  • Regular exercise under the supervision of a gynecologist is necessary during pregnancy.
  • Avoid alcohol, tobacco and harmful drug use during pregnancy to prevent the risk of VSD.
  • Get vaccinated: Check whether you are vaccinated for vaccine-preventable infections before getting pregnant.
  • Control diabetes: Monitor your sugar levels regularly to prevent the risk of heart defects.

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What is an Atrial Septal Defect or ASD? 

Heart consists of four chambers, of which upper two chambers are called as atria and lower two chambers are called as ventricles. Atrial septal defect (ASD) is a type of congenital heart defect, in which there is an abnormal opening or a hole in interatrial septum (dividing wall between two atria). This opening allows the passage of pulmonary venous blood from left atrium to right atrium, causing mixing of oxygenated and deoxygenated blood in right atrium and increasing the flow of blood to lungs. The increased blood flow may increase the workload of the lungs, and eventually cause damage to heart and lungs.

 

What causes an ASD?

The exact cause of ASD remains unclear. However, it is believed that during fetal developmental stages, a hole is present in the interatrial septum, which gradually closes before birth or during infancy. If the hole persists, it is called an atrial septal defect.

Types of Atrial Septal Defect or ASD?

Based on the location and development of ASD, it is classified into four types:

  • Ostium secundum ASD: It occurs in the middle part of the interatrial septum. This is the most common type of ASD and accounts for 75% of all atrial septal defects. This type of ASD is commonly detected in adults in their third and fourth decades of life. Some can be detected in children when an abnormal heart sound is detected at the time of a routine health check or vaccination visit. 
  • Ostium primum ASD (20%): It occurs in the lower part of the interatrial septum, adjacent to atrioventricular (AV) valves. It usually occurs as a part of other congenital heart defects. This defect is usually detected in early life as this is associated with many complications.
  • Sinus venosis ASD (4%): It occurs in the upper part of the interatrial septum, near the veins that drain into the right and left atrium. This is usually identified in third and fourth decade adults. 
  • Coronary sinus ASD (<1%): It occurs in the interatrial septum between the coronary sinus and the left atrium. This is very uncommon and patients are asymptomatic.

Signs and symptoms: Usually after birth, babies who have ASD may not show any associated signs and symptoms. But, symptoms may appear during adulthood around the age of 30 years. Most of them don’t have any symptoms even after many years.

Some of the common symptoms associated with ASD are:

  • Heart murmur, a swishing sound that can be heard through a stethoscope
  • Heart palpitations
  • Arrhythmias (abnormal heart rhythms)
  • Fatigue (feeling tired mainly after exercise)
  • Shortness of breath
  • Swelling of legs, feet or abdomen
  • Stroke
  • Lung infections such as pneumonia

 

Risk factors:

Genetics and environmental factors usually play a role in congenital heart defects. Some conditions during pregnancy may confer high risk for heart defects, 

Complications of an untreated ASD:

  • Right-sided heart failure
  • Arrhythmias
  • Increased risk of a stroke
  • Shortened life span
  • Pulmonary hypertension (increased blood flow to the lungs results in increased blood pressure in the lung arteries)
  • Eisenmenger syndrome (pulmonary hypertension causing permanent lung damage)

 

Diagnosis:

Most ASDs are diagnosed incidentally during regular heath check-ups. If a heart murmur is heard during auscultation, you may be advised to undergo further tests to confirm the diagnosis of ASD: 

  • Echocardiogram: It is a specific diagnostic test for ASD, and provides a detailed image of the heart and blood flow through its chambers. The echocardiogram may show the blood flow through the interatrial septum and the size of defect in the septum.
  • Chest X-ray: It helps to identify enlarged heart and lung changes.
  • Electrocardiogram (ECG): It involves recording the electrical activity of the heart, to help identify arrhythmias.
  • Cardiac catheterization: A thin, flexible tube called catheter is inserted into the blood vessel at the groin or arm and is guided to the heart. This test is helpful to determine the function of heart and its valves, and to measure the blood pressure in the lungs.
  • Magnetic resonance imaging (MRI): It uses magnetic and radio waves to create three dimensional images of the heart and other organs. This test is recommended if the ASD is not clearly diagnosed with echocardiogram.
  • Computerized tomography (CT) scan: It uses a series of X-rays to create detailed images of heart; mainly used if echocardiogram doesn’t help to diagnose ASD clearly.

 

Treatment:

Treatment of ASD depends on the age at diagnosis and the size, location and severity of the defect. Small ASDs might not need any treatment because it closes on its own. The doctor may recommend surgery if the atrial septal defect is large, even with fewer symptoms to prevent problems later in life. Treatment of ASD includes medications and surgery.

  • Medications usually do not help in closing the hole, but reduces the signs and symptoms associated with ASD and risks of complications after surgery. Drugs such as beta blockers (to maintain regular heartbeat) and anticoagulants (to prevent the formation of blood clots) are used.
  • Surgery includes cardiac catheterization and open-heart surgery.

Device closure of ASD

In cardiac catheterization, the doctor closes the hole in the septum with a mesh patch or a plug in the defect place using a catheter. The heart tissue then grows around the mesh slowly, sealing the hole permanently. This procedure is mainly performed to repair only the secundum type of atrial septal defects. Defects not amenable to closure with device may need open-heart surgery.

In open-heart surgery, the defect may be closed with stitches or a special patch. This procedure is done under general anesthesia, mainly for repairing primum, sinus venosus and coronary sinus atrial septal defects.

Prevention of ASD:

Atrial septal defects cannot be prevented, but following certain measures during pregnancy might be beneficial to prevent the risk of ASD, such as:

  • Immunity test for rubella: If the person is not immune to rubella, it is necessary to get vaccinated.
  • Monitoring current health conditions and medications use: Pre-existing health conditions and usage of any medications should be carefully monitored during pregnancy to prevent the risk of ASD.
  • Reviewing family medical history: If a person has a family history of congenital defects, it is advised to visit a genetic counsellor before becoming pregnant to know the risks of atrial septal defects.

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Coronary arteries  are the vessels which supply blood (oxygen and nutrients) to the heart; this supply may be disrupted due to buildup of cholesterol and fatty deposits, called plaques, on the inner walls of the arteries (atherosclerosis) causing narrowing of the vessel lumen.

Coronary lesions branch out as they progress to supply various cardiac structures. A bifurcation lesion is a stenosis or abnormal narrowing of greater than 50% that occurs in a coronary artery at the origin of the side branch or adjacent to the origin of the side branch. Branching points a.k.a bifurcation points in the coronary arteries are prone to develop atherosclerosis as the shear stress is higher at the branch points.

The figure shows how a bifurcation stenosis appears schematically as well as on angiography.

Why bifurcation lesions are important?

A vast majority of coronary arteries‘ obstructions happen at the branching point. About 15-20% of patients of referrals for bypass surgery are because of the presence of coronary narrowing at bifurcation location. They are considered a tough lesion to treat by angioplasty and stent. 

 How are bifurcation lesions diagnosed?

Bifurcation lesions are identified on coronary angiography. Only lesions affecting side branch blood vessels more than 2.25 mm is considered important and called bifurcation lesions. The main vessel that gives branches is called main vessel and the branches that originate from it are called side branches. The point at the division of the main vessel and side branch is called a bifurcation point. 

How is a bifurcation lesion unique?

Bifurcation lesions can involve the coronary artery either before or after the bifurcation point. In addition, side branches could be either diseased or free from disease. Based on the location and severity of the cholesterol plaque at the bifurcation point, sub types of bifurcation lesions have been identified. 

The challenge of performing angioplasty and stent for a bifurcation stenosis lies in the ability to preserve the main vessel and the side branch. Stents being metallic tubes risk occluding the side branch when placed across the side branch. This apprehension of losing the side branch, is one of the primary reasons for patients to be sent for bypass surgery instead of angioplasty and stent.

Can angioplasty and stent be performed for a bifurcation lesion?

Angioplasty and stent can be eminently performed for a bifurcation stenosis. Over the last 2 decades numerous techniques in stent implantation have been developed to treat the bifurcation lesions. Some of these techniques include:

  • Provisional T stent technique 
  • Tap technique 
  • Double kiss crush technique 
  • Culotte technique

Advent of these techniques enabled experienced operators to perform angioplasty and stent successfully with chances of repeat narrowing seen in 3-6% patients at the site of stenting. Risk of losing a side branch after stenting is reduced to 1% once the new techniques are employed.

Dr. C Raghu is an expert in bifurcation lesion angioplasty and the center where he has been trained, ICPS Paris France is considered the “Mecca” for bifurcation lesion angioplasty techniques development. 

How does a bifurcation lesion angioplasty differ from a normal angioplasty?

Bifurcation lesion angioplasty, involves utilization of novel stent techniques mentioned above. In addition, angioplasty operator experience is a major factor in determining  outcomes. Choosing the “right” stent that allows side branch access, use of specialized technologies such as fractional flow reserve (FFR), expertise in deploying 2 stents especially the process of “stent crush” and the handling of two balloons through a single catheter – kissing balloon are key points for the best results in a stent procedure. 

 

What are the chances of side branch occlusion in a bifurcation lesion angioplasty?

Contemporary bifurcation angioplasty using Intravascular imaging employing contemporary stenting techniques in the hands of expert bifurcation angioplasty operators carries a 99% success rate with a chance of losing side branch in 1% and repeat narrowing at the end of 9 months being 3-6%. These results are comparable and if not superior to bypass surgery as angioplasty entails a short hospital stay and fast recovery.












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