In 1925, Henry souttar of the London Hospital wrote in the BMJ in the introduction to his report of the first mitral commissurotomy, that the heart should be as amenable to surgery as any other organ and that many of the problems in heart disease were to a large extent mechanical.
The first real steps in surgery in and around the heart came in the late 1940s and early 1950s.
In the mid 1950s, cardiopulmonary bypass (Heart and lung machine) was developed.
Now, the number, range and technical complexity of heart operations are remarkable.
Surgical Anatomy of the Heart the anatomy of the heart is viewed from the right side of the supine patient via a median sternotomy incision. The structures initially seen from this perspective include the superior vena cava, right atrium, right ventricle, pulmonary artery, and aorta. Medial displacement of the right side of the heart exposes the left atrium and right pulmonary veins. Medial rotation from the left exposes the left ventricle apex, left pulmonary veins, and left atrium.
Location of the Heart Relative to Surrounding Structures
The overall shape of the heart is that of a three-sided pyramid located in the middle mediastinum.
One-third of the cardiac mass lies to the right of the midline and two-thirds to the left
The long axis of the heart is oriented from the left epigastrium to the right shoulder .
Anteriorly, the heart is covered by the sternum and the costal cartilages of the third, fourth, and fifth ribs.
The lungs contact the lateral surfaces of the heart, whereas the heart abuts onto the pulmonary hila posteriorly .
The sternum lies anteriorly and provides rigid protection to the heart during blunt trauma and is aided by the cushioning effects of the lungs.
The heart lies within the pericardium, which is attached to the walls of the great vessels and to the diaphragm. The pericardium can be visualized best as a bag into which the heart has been placed apex The inner layer, in direct contact with the heart, is the visceral epicardium, which encases the heart and extends several centimeters back onto the walls of the great vessels. The outer layer forms the parietal pericardium, which lines the inner surface of the tough fibrous pericardial sack. A thin film of lubricating fluid lies within the pericardial cavity between the two serous layers.
The superior vena cava and inferior vena cava drain systemic venous blood into the posterior wall of the right atrium. The internal wall of the right atrium is composed of a smooth posterior portion (into which the vena cavae and coronary sinus drain) and a ridge like muscular anterior portion. The coronary sinus drains coronary venous blood into the anteroinferior portion of the right atrium. The thebesian valve is located at the orifice of the coronary sinus. The limbus of the fossa ovalis is located on the medial wall of the right atrium and circumscribes the septum primum of the fossa ovalis anteriorly, posteriorly, and superiorly.
The right auricle is separated from the right atrium by a shallow posterior vertical indentation on the right atrium (ie, the sulcus terminalis) and, internally, by a vertical crest (ie, the crista terminalis). The crista terminalis separates the right atrium into trabeculated and nontrabeculated portions.
The 4 pulmonary veins drain into the left atrium. The flap valve of the fossa ovalis is located on the septal surface of the left atrium. The appendage of the left atrium is consistently narrow and long; recognition of this appendage is the most reliable way to differentiate the left atrium from the right atrium. The left atrial appendage is the only trabeculated structure in the left atrium because, unlike the right atrium, the left atrium has no crista terminalis
The right ventricle receives blood from the right atrium across the tricuspid valve, which is located in the large anterolateral portion of the right ventricle. The right ventricle discharges blood into the pulmonary artery across the pulmonic (semilunar) valve located in the outflow tract (infundibulum).
The septal portion of the right ventricle has 3 components: (1) the inflow tract, which supports the tricuspid valve; (2) the trabecular wall, which typifies the internal appearance of the right ventricle; and (3) the outflow tract, which itself is subdivided into 3 components, namely, the conal septum, septal band division, and trabecular septum.
The tricuspid valve is supported by a large anterior papillary muscle, which arises from the anterior free wall and the moderator band, and by several small posterior papillary muscles, which attach posteriorly to the septal band.
The left ventricle receives blood from the left atrium via the mitral (ie, bicuspid) valve and ejects blood across the aortic valve in the aorta. The left ventricle can be divided into 2 primary portions, namely, the large sinus portion containing the mitral valve and the small outflow tract that supports the aortic (semilunar) valve.
The free wall and apical half of the septum contain fine internal trabeculations. The septal surface is divided into a trabeculated portion (sinus) and a smooth portion (outflow).
The left half of the anterior mitral leaflet is in direct fibrous contact with the aortic valve at the aortic-mitral annulus. The conal septum of the right ventricle is positioned opposite the aortic valve. The mitral valve is supported by 2 large papillary muscles (ie, anterolateral, posteromedial) attached to the free wall. The anterior papillary muscle is attached to the anterior portion of the left ventricular wall, and the posterior papillary muscle arises more posteriorly from the ventricle's inferior wall.
The aorta begins at the base of the heart and typically branches to form the coronary arteries just distal to the aortic valve. In patients with cardiac malformations, the aorta almost always can be identified by tracing it back from the brachiocephalic arteries, which only very rarely originate from the pulmonary artery.
The main pulmonary artery branches into the pulmonary arterial system. In patients with aberrant cardiac anatomy with a patent ductus arteriosus , accurate identification of the pulmonary artery can be difficult using angiography because the pulmonary artery becomes opaque during aortic injection. To differentiate the pulmonary artery from the aortic valve, remember that the pulmonary artery almost never gives off brachiocephalic branches.
The ventricular septum is divided into a muscular section (inferior) and a membranous section (superior). The muscular portion comprises the left and right ventricular walls. The membranous septum, also termed the pars membranacea, is a fibrous structure partially separating the left ventricular outflow tract from the right atrium and ventricle.
The atrioventricular (AV) septum, located behind the right atrium and left ventricle, is divided into 2 portions: a superior portion (membranous) and an inferior portion (muscular). Inside the left ventricle, the muscular component comprises part of the outlet septum. The AV node lies in the atrial septum, juxtaposed to the membranous and muscular portions of the AV septum
Cardiac valves are categorized into 2 groups, based on function and morphology. Mitral and tricuspid valves comprise the atrioventricular (AV) group; aortic and pulmonary valves comprise the semilunar group. On cross section, the aortic valve is located in a central location, halfway between the mitral and tricuspid valves. The pulmonary valve is positioned anterior, superior, and slightly to the left of the aortic valve. The tricuspid and mitral anuli merge and fuse with each other and with the membranous septum to form the fibrous skeleton of the heart.
The AV valve of the left ventricle is bicuspid. The AV valve has a large anterior leaflet (septal or aortic) and a smaller posterior leaflet (mural or ventricular). The anterior leaflet is triangular with a smooth texture. The posterior leaflet has a scalloped appearance. The chordae tendineae to the mitral valve originate from the 2 large papillary muscles of the left ventricle and insert primarily on the leaflet's free edge.
The AV valve of the right ventricle has anterior, posterior, and septal leaflets. The orifice is larger than the mitral orifice and is triangular. The tricuspid valve leaflets and chordae are more fragile than those of the mitral valve. The anterior leaflet, largest of the 3 leaflets, often has notches. The posterior leaflet, smallest of the 3 leaflets, is usually scalloped. The septal leaflet usually attaches to the membranous and muscular portions of the ventricular septum
The aortic valve has 3 leaflets composed of fragile cusps and the sinuses of Valsalva. Thus, the valve apparatus is composed of 3 cuplike structures that are in continuity with the membranous septum and the mitral anterior leaflet. The free end of each cusp has a stronger consistency than the cusp. The midpoint of each free edge contains the fibrous nodulus arantii, which bisects the thin crescent-shaped lunula on either side.
The aortic sinuses of Valsalva are 3 dilations of the aortic root that arise from the 3 closing cusps of the aortic valve. The right and left sinuses give rise to the right and left coronary arteries; the noncoronary sinus has no coronary artery. The sinus of Valsalva walls are much thinner than the aortic wall, which is a factor of surgical significance; therefore, aortotomies are typically performed away from this region
As with the aortic valve, the pulmonary valve has 3 cusps, with a midpoint nodule at the free end and lunulae on either side; a sinus is located behind each cusp. Compared with the aortic valve, the pulmonary valve has thinner cusps, no associated coronary arteries, and no continuity with the corresponding (anterior) tricuspid valve leaflet. The term used for each cusp reflects its relationship to the aortic valve, namely, right, left, and nonseptal.
The 2 main coronary arteries are the right and left. However, from a surgical standpoint, 4 main arteries are named: the left main, the left anterior descending, and the left circumflex (LCX) arteries (which are all branches of the left coronary artery) and the right coronary artery (RCA). The RCA and LCXs form a circle around the atrioventricular (AV) sulci. The left anterior descending and posterior descending arteries form a loop at right angles to this circle; these arteries feed the ventricular septum. The LCX gives off several parallel, obtuse, marginal arteries that supply the posterior left ventricle. The diagonal branches of the left anterior descending artery supply the anterior portion of the left ventricle.
The term dominance is used to refer to the origin of the posterior descending artery (PDA). When the PDA is formed from the terminal branch of the RCA (>85% of patients), it is termed a right-dominant heart. A left-dominant heart receives its PDA blood supply from a left coronary branch, usually the LCX. This is often referred to as a left posterolateral branch (LPL
The left main coronary artery (LCA) originates from the ostium of the left sinus of Valsalva. The LCA, which courses between the left atrial appendage and the pulmonary artery, typically is 1-2 cm in length. When it reaches the left AV groove, the LCA bifurcates into the left anterior descending (LAD) and the LCX branches. The LCA supplies most of the left atrium, left ventricle, interventricular septum, and AV bundles. The LCA arises from the left aortic sinus and courses between the left auricle and the pulmonary trunk to reach the coronary groove.
After originating from the left main artery, the LAD artery runs along the anterior interventricular sulcus and supplies the apical portion of both ventricles. The LAD artery is mostly epicardial but can be intramuscular in places. An important identifying characteristic of the LAD artery during angiography is the identification of 4-6 perpendicular septal branches. These branches, approximately 7.5 cm in length, supply the interventricular septum.
As the LAD artery courses anteriorly along the ventricular septum, it sends off diagonal branches to the lateral wall of the left ventricle.
The LCA gives off the LCX artery at a right angle near the base of the left atrial appendage. The LCX artery courses in the coronary groove around the left border of the heart to the posterior surface of the heart to anastomose to the end of the RCA. In the AV groove, the LCX artery lies close to the annulus of the mitral valve. The atrial circumflex artery, the first branch off the LCX artery, supplies the left atrium. The LCX artery gives off an obtuse marginal (OM) branch at the left border of the heart near the base of the left atrial appendage to supply the posterolateral surface of the left ventricle.
The RCA is a single large artery that courses along the right AV groove. The RCA supplies the right atrium, right ventricle, interventricular septum, and the SA and AV nodes. The RCA arises from the right aortic sinus and courses in the coronary (AV) groove between the right auricle and the right ventricle. In 60% of patients, the first branch of the RCA is the sinus node artery. As the RCA passes toward the inferior border of the heart, it gives off a right marginal branch that supplies the apex of the heart. After this branching, the RCA turns left to enter the posterior interventricular groove to give off the PDA, which supplies both ventricles.
The coronary sinus is a short (approximately 2 cm) and wide venous channel that runs from left to right in the posterior portion of the coronary groove. The opening of the coronary sinus is located between the right atrioventricular (AV) orifice and the inferior vena cava orifice. The coronary sinus drains all venous blood from the heart except the blood carried from the anterior cardiac veins. The coronary sinus receives outflow from the great cardiac vein on the left and from the middle and small cardiac veins on the right.
These are carried out on the main vessels outside the heart or on the pericardium. The ventricles or atria are not directly interfered with so that cardiac function is not disturbed. Examples include ligation of a patent ductus, excision of coarctation, systemic-pulmonary anastomoses, pericardiectomy and resection of some thoracic aortic aneurysms.
These are blind intracardiac procedures performed by instrument or finger and controlled by touch. Access is obtained to the interior of the heart through either the ventricular or atrial walls or through the base of one of the great vessels. Cardiac action is interfered with to some extent so that irregularity of heart action is liable to be encountered. Mitral valvotomy is the only closed procedure still used regularly.
The desire of every surgeon is to operate with safety under direct vision on the open and motionless heart. Cardiopulmonary bypass ( extra-corporeal circulation ) allows the surgeon to manage the circulation while operating on a still heart in a bloodless field
Several clinically proven heart- lung machines are now in regular use. Basically each consists of a pump and an oxygenator. Blood is withdrawn from the venae cavae, passed through the oxygenator and returned into the arterial circulation through the femoral artery or ascending aorta. The blood is thus diverted completely from the heart and lungs but a good supply of well oxygenated blood is made available to the vital organs.
Heart lung machines provide the surgeon with periods for intracardiac surgery of between 2 or 3 hours with safety. By the use of an extra-corporeal circulation many complicated cardiac anomalies can be corrected and such conditions as VSD, Fallot, s Tetralogy and valvular abnormalities are being so treated.
The majority of cardiac anomalies can be treated through a median sternotomy incision. The heart is exposed through a vertical incision. Both venae cavae and the ascending aorta are circumvented with tapes. Immediately prior to cannulation the patient is heparinised with 3 mg/ kg body weight. The ascending aorta is cannulated with a plastic tube through a purse string suture placed in the aortic adventitia and each cava is similarly cannulated through the right atrial wall.
The cannulae are connected to the heart-lung machine after careful elimination of all bubbles of air. At the completion of the operation the cannulae are removed and the heparin is counteracted with protamine (6 mg/kg body weight). During heart-lung bypass the efficiency of the extracorporeal circulation is monitored by observing urinary output and cerebral activity, by measurement of blood gases and determination of serum potassium.
The ideal situation for the surgeon operating on the heart is to have a still heart in a bloodless field. To render the heart bloodless, the aorta must be cross-clamped to prevent coronary perfusion. The heart is then rendered ischaemic. One way of coping with this ischaemia without causing lasting myocardial damage is cardioplegic arrest.
There are various cardioplegic solutions which arrest the heart in diastole and preserve ATP levels. They all have high potassium levels and may be crystalloid or contain blood. With the patient on full cardiopulmonary bypass, the core temperature is reduced to 26-28 0C and the aorta is cross-clamped. Cardioplegic solution is infused into the aortic root and topical cooling with iced slush may also be employed to increase myocardial protection. The heart can be kept arrested for up to 2 hours with this technique.
Congenital heart disease occurs when the heart or blood vessels near the heart do not develop properly before birth . Some infants are born with mild types of congenital heart disease, but most need surgery in order to survive . Patients who have had surgery are likely to experience other cardiac problems later in life .
Most types of congenital heart disease obstruct the flow of blood in the heart or the nearby vessels, or cause an abnormal flow of blood through the heart . Rarer types of congenital heart disease occur when the newborn has only one ventricle, or when the pulmonary artery and the aorta come out of the same ventricle, or when one side of the heart is not completely formed .
Patent ductus arteriosus refers to the opening of a passageway—or temporary blood vessel ( ductus ) —to carry the blood from the heart to the aorta before birth, allowing blood to bypass the lungs, which are not yet functional . The ductus should close spontaneously in the first few hours or days after birth . When it does not close in the newborn, some of the blood that should flow through the aorta then returns to the lungs . Patent ductus arteriosus is common in premature babies, but rare in full - term babies . It has also been associated with mothers who had German measles ( rubella )while pregnant .
Hypoplastic left heart syndrome, a condition in which the left side of the heart is underdeveloped, is rare, but it is the most serious type of congenital heart disease . With this syndrome, blood reaches the aorta, which pumps blood to the entire body, only from the ductus, which then normally closes within a few days of birth . In hypoplastic left heart syndrome, the baby seems normal at birth, but as the ductus closes, blood cannot reach the aorta and circulation fails .
When heart valves, arteries, or veins are narrowed, they partly or completely block the flow of blood . The most common obstruction defects are pulmonary valve stenosis , aortic valve stenosis , and coarctation of the aorta . Bicuspid aortic valve and subaortic stenosis are less common .
Stenosis is a narrowing of the valves or arteries . In pulmonary stenosis, the pulmonary valve does not open properly, forcing the right ventricle to work harder . In aortic stenosis, the improperly formed aortic valve is narrowed . As the left ventricle works harder to pump blood through the body, it becomes enlarged . In coarctation of the aorta, the aorta is constricted, reducing the flow of blood to the lower part of the body and increasing blood pressure in the upper body .
A bicuspid aortic valve has only two flaps instead of three, which can lead to stenosis in adulthood . Subaortic stenosis is a narrowing of the left ventricle below the aortic valve, that limits the flow of blood from the left ventricle .
When a baby is born with a hole in the septum ( the wall separating the right and left sides of the heart ) , blood leaks from the left side of the heart to the right, or from a higher pressure zone to a lower pressure zone . A major leakage can lead to enlargement of the heart and failing circulation . The most common types of septal defects are atrial septal defect , an opening between the two upper heart chambers, and ventricular septal defect , an opening between the two lower heart chambers . Ventricular septal defect accounts for about 15% of all cases of congenital heart disease in the United States .
Heart disorders that cause a decreased, inadequate amount of oxygen in blood pumped to the body are called cyanotic defects . Cyanotic defects, including
truncus arteriosus, total anomalous pulmonary venous return , tetralogy of Fallot , transposition of the great arteries , and tricuspid atresia, result in a blue discoloration of the skin due to low oxygen levels . About 10% of cases of congenital heart disease in the United States are tetralogy of Fallot, which includes four defects . The major defects are a large hole between the ventricles, which allows oxygen - poor blood to mix with oxygen - rich blood, and narrowing at or beneath the pulmonary valve . The other defects are an overly muscular right ventricle and an aorta that lies over the ventricular hole .
In transposition ( reversal of position ) of the great arteries, the pulmonary artery and the aorta are reversed, causing oxygen - rich blood to re - circulate to the lungs while oxygen - poor blood goes to the rest of the body . In tricuspid atresia, the baby lacks a triscupid valve and blood cannot flow properly from the right atrium to the right ventricle .
Medications used to treat congenital cardiovascular defects include diuretics , which aid the child in excreting water and salts, and Digoxin, which strengthens the contraction of the heart, slows the heartbeat , and removes fluid from tissues. A potassium supplement may be prescribed along with diuretics , which remove potassium from the body along with excess fluid. Heart rate control drugs and antiarrhythmic drugs may be prescribed to treat irregular heart rhythms. Other medications may include anticoagulants (blood thinners) to reduce the risk of blood clots and stroke , ACE inhibitors to decrease artery constriction and improve blood flow, and inotropes to strengthen the heart's contractions
The goal of surgery is to repair the defect as much as possible, restore circulation to as close to normal as possible, reduce symptoms, improve survival, and improve quality of life. Sometimes, multiple surgical procedures are necessary. Surgery for most congenital cardiovascular defects has low risk of death (less than 2 percent), compared to 80–100 percent in the 1940s. Surgical procedures used to treat congenital cardiovascular defects include:
arterial switch : Arterial switch, to correct transposition of the great arteries
balloon atrial septostomy
Damus-Kaye-Stansel procedure : Transposition of the great arteries also can be corrected by the Damus-Kaye-Stansel procedure,
Fontan procedure the Fontan procedure connects the right atrium to the pulmonary artery directly or with a conduit , :
pulmonary artery banding : narrowing the pulmonary artery with a band to reduce blood flow and pressure in the lungs,
Ross procedure: the Ross procedure grafts the pulmonary artery to the aorta
Heart valve Control the direction of blood flow through the four chambers of the heart ( two atrium and two ventricles ). The valves act likes one-way door and stop blood from running back wards.
Blood that has been pumped around the body returns to the heart by large veins and flow into the right atrium then through the tricuspid valve into the right ventricle. From here, blood is pumped through the pulmonary valve to the lung to pick up oxygen. The blood then re-enters the heart into the left atrium through the Pulmonary veins and goes to the left ventricle through the Mitral Valve . From the left ventricle the blood is pumped through the aortic valve into the aorta and on to the rest of the body.
This is mostly due to rheumatic fever. This is sequel of Group–A Streptococcal-tonsillopharyngytis infection of the throat. This involves mainly major joints and heart. Cardiac symptoms are mainly inflammatory lesions of heart valves. Eventually it will lead to cicatrisation and deformity of valve at a later date. Rheumatic valvular heart disease may lead to obstruction, or leakage of the heart valve and many a time both can co-exist. It is the left sided heart valves ( Mitral or Aortic ) which get commonly affected. Usually it takes 7-10 yrs after rheumatic fever before the symptoms of heart valve disease appear. Apart from this heart valve can be damaged due to direct infection of the valve itself. This is called infective endocarditis.
Sometimes the obstructed valve can be opened surgically by splitting open the fused area. Also the leaking valve can be repaired by excising the redundant or prolapsed segment and by preventing dilation of the valve by a prosthetic ring. Valve repairs have important role while operating on children and women of childbearing age where anticoagulation can be avoided.
If it is not possible to repair the valve then it is replaced with a prosthetic material. A new valve is sewn into its place by open-heart surgery . There are different types of valves available in market. Biological valves are made from human or animal tissue. The advantage of this valve is that there is no need for anticoagulation tablets after 3 months. However these valves have limited life span and start degenerating beyond ten years. Therefore these valves are usually implanted over the age of 65 yrs or those patients who wants to avoid anticoagulation tablets. Mechanical valves are made from an alloy of several metals. This alloy is called Pyrolytic Carbon . These valves last forever. However because they are not made from natural tissue it is necessary to take anticoagulation tablets life long to prevent clot formation over the valve. For maintaining adequate level of anticoagulation it is necessary to do regular blood test ( called INR test ) This can be done in any standard laboratory and the desired valve should be 2-2.5 . Higher INR is associated with bleeding problem. It starts with gum or nasal bleeding and may lead to bleeding inside stomach and brain. Sometimes it may be fatal. Similarly low INR level < 2.0 may lead to clot formation over the valve which may then go to any organs of the body
Cardiopulmonary bypass (CPB) is a technique that temporarily takes over the function of the heart and lungs during surgery , maintaining the circulation of blood and the oxygen content of the body. The CPB pump itself is often referred to as a Heart-Lung Machine or the Pump . Cardiopulmonary bypass pumps are operated by allied health professionals known as perfusionists in association with surgeons who connect the pump to the patient's body. CPB is a form of extracorporeal circulation
Cardiopulmonary bypass consists of two main functional units, the pump and the oxygenator which remove oxygen-deprived blood from a patient's body and replace it with oxygen-rich blood through a series of hoses.
Coronary artery bypass grafting (CABG) is a type of surgery called revascularization, used to improve blood flow to the heart in people with severe coronary artery disease (CAD). CABG is one treatment for CAD. During CABG, a healthy artery or vein from another part of the body is connected, or grafted, to the blocked coronary artery. The grafted artery or vein bypasses (that is, it goes around) the blocked portion of the coronary artery. This new passage routes oxygen-rich blood around the blockage to the heart muscle. As many as four major blocked coronary arteries can be bypassed during one surgery
a combination of both artery and vein grafts is commonly used.
Artery grafts. These grafts are much less likely than vein grafts to become blocked over time. The left internal mammary artery is most commonly used for an artery graft. It's located inside the chest close to the heart. Arteries from the arm or other places in the body are sometimes used as well.
Vein grafts. Although veins are commonly used as grafts, they're more likely than artery grafts to develop plaque and become blocked over time. The saphenous vein-a long vein running along the inner side of the leg-is typically used