Lecture 2 Heart Diseases PDF

Lectur 2 Heart pathology Dr. Ikram Abdul Latif Hasan Infective Endocarditis (EC): Microbial invasion of the endocardium with destruction of the underlying cardiac tissues. Majority of cases is caused by bacteria, although fungi, rickettsiae &chlamydiae can cause endocardit...

Lectur 2 Heart pathology Dr. Ikram Abdul Latif Hasan Infective Endocarditis (EC): Microbial invasion of the endocardium with destruction of the underlying cardiac tissues. Majority of cases is caused by bacteria, although fungi, rickettsiae &chlamydiae can cause endocarditis 2 types: acute &subacute, depending on: The intrinsic microbial virulence &whether underlying cardiac disease is present. Etiology &pathogenesis: It occurs during episodes of bacteremia e.g: intravenous drug abusers, tonsillectomy, infection elsewhere, previous dental or surgical procedures e.g catheterization, trivial skin injury. Conditions increase risk: 1- Abnormalities of the heart: Any condition cause increase hemodynamic trauma to the endothelial surface e.g Ventricular septal defect (VSD) Rheumatic fever (RF) calcific aortic stenosis mitral prolapse. 2- Prosthetic heart valves. 3- Impaired defense mechanisms like immune deficiency diseases &cytotoxic drugs. Subacute bacterial endocarditis: SBE * Caused by low virulent microorganisms e.g strep. viridance of alfa hemolytic group (mouth), staph albus (skin). * The valve is already diseased &the bacteria adheres to the injured surface of the valve---proliferate + fibrin +platelets + leukocytes---vegetations which project from the surface. Grossly: (Vegetations of IE) Large size Friable Not sterile Give rise to emboli. Microscop.: Consist of platelets + fibrin + few leukocytes + bacterial colonies, but the vegetations of SBE are firmer &associated with less valvular destruction &less likely to erode the myocardium. Clinical features: Fever malaise mild anemia weight loss. Systemic emboli because of the friable nature of the vegetations &because the emboli contain large numbers of m.o, abscess often develop---septic infarcts. * Effects of embolization in all forms: Kidney---renal infarcts &glomerulonephritis---hematuria. Enlarged spleen &clubbing of nails especially in SIE. Neurological deficits, retinal hemorrhage &blindness. Skin---petechiae. Nails---splinter hemorrhage. Causes of death: 1- Heart failure due to MI or cusps rupture. 2- Renal failure. Without treatment, it is fatal but with early treatment, the mortality decreases to 15%. Acute infective endocarditis (AIE): More severe inf. Than SIE. Caused by highly virulent m.o e.g staph. areus, strep. Pyogenes, enterococci. Fatal without treatment &with treatment the mortality decreases to 50% Occur on previously normal valves. Vegetations of AIE: are larger, bulky friable that obstruct valve orifice &cause rupture of leaflets, papillary muscles, chordae & the infection may extend into adjacent myocardium---perivalvular abscess (ring abscess). Microscop.: Consist of larger number of m.o + fibrin &blood cells, more severe damage to the valve due to rapid destruction, necrosis, suppuration which extend from cusps---chordae---myocardium &aorta (mycotic aneurysm).Aortic &mitral valves are commonly affected.  Clinical features: High fever, shaking chills &other evidences of overt septicemia, blood culture is more positive than in SBE. Subacute endocarditis A less destructive. Involving a previously abnormal heart, particularly deformed valves. Caused by m.o. of low virulence (e.g.Streptococcus viridans). Associated with insidious and protracted course (weeks to months). Sub-acute IE recovers after appropriate antibiotic therapy. Acute endocarditis an infection that is: Destructive. Involving frequently a normal heart valve. Caused by high virulence m.o. (e.g staphylococcus aureus) Associated with a rapid course leading to death within days to weeks of more than 50% of the patients despite treatment The disease is difficult to cure by antibiotics and usually require surgery Non-bacterial thrombotic endocarditis (NBTE): Or so called marantic endocarditis: it is non infective tend to occur in NORMAL VAVE in the following conditions: 1-malignant tumors (particularly adenocarcinomas) or 2-prolonged debilitating illness (e.g., renal failure, chronic sepsis) 3-with disseminated intravascular coagulation (DIC) or other hypercoagulable states (Troussea"s syndrome) The size of the vegetations may be o.5 cm, loosely adherent to valve leaflets, without significant inflammation or valve damage (nondestructive), or it can embolize systemically that produce significant infarcts in the brain, heart, or elsewhere. Libman-Sacks endocarditis (LSE) Endocarditis of Systemic lupus erythematosus (SLE) In some SLE patients, there is mitral and tricuspid valvulitis complicated by presence of small, sterile vegetations on either or both sides of the valve leaflets Subsequent fibrosis can lead to serious valvular deformities that resemble chronic Rheumatic heart disease. Congenital Heart Disease (CHD) Etiology and pathogenesis: 1- Genetic factors: certain chromosomal abnormalities (e.g., trisomies associated with CHD 13, 15, 18, and 21, and Turner syndrome) are Trisomy 21 (Down syndrome) is the most commonly known genetic cause of CHD, roughly 40% of patients with Down syndrome have one or more heart defects. DiGeorge syndrome: a chromosomal lesion caused by deletion of chromosome 22q11.2. 2- Environmental factors include: Congenital rubella infection, maternal use of certain drugs in early pregnancy (e.g thalidomide, alcohol, phenytoin, amphetamines and estrogenic steroids). Maternal diabetes Nutritional factors: folate supplementation during early pregnancy reduces CHD incidence. The most common are (in descending order of frequency): 1.Ventricular septal defect (VSD) (42%). 2.Atrial septal defect (ASD) (10%). 3.Pulmonary stenosis (8%) 4.Patent ductus arteriosus (PDA) (7%). 5.Tetralogy of Fallot (5%). 6. Coarctation of aorta (5%). Classifications of Congenital Heart Disease This classification based on the presence or absence of cyanosis: 1- Cyanosis (blue baby) T Right to left shunt Venous emboli can become systemic Tetralogy of Fallot (TOF)  Transposition of the great arteries Truncus arteriosus, Total anomalous pulmonary venous connection and Tricuspid atresia No cyanosis Cyanose tardive D Initial Left to right shunt Ventricular septal defect (VSD) Atrial septal defect (ASD) Atrioventricular septal defect (AVSD) Patent ductus arteriosus (PDA) Then Pulmonary hypertension, Significant pulmonary hypertension is irreversible, Reverse of the shunt Then become cyanotic No cyanosis Obstruction 1-Coarctation of aorta 2-Aortic valve stenosis 3-Pulmonary valve stenosis 1- Cyanotic heart diseases: Include: 1- Tetralogy of Fallot (TOF): about 5% of all congenital malformations. Of 4 components: Pulmonary stenosis (right ventricular outflow obstruction) Right ventricular hypertrophy. VSD (ventricular septal defect). Overriding of the aorta. Morphology: Enlarged boot shaped heart because of right ventricular hypertrophy, Clinically: Right to left shunt, decrease blood flow to the lung, increase blood flow through aorta. Extent of shunt (the clinical severity) is determined by degree of pulmonary stenosis. Mild stenosis resembles VSD because of high pressure on left side causing left to right shunt &no cyanosis. Marked stenosis causes significant cyanosis early in life. Lung protected from hemodynamic load by pulmonary stenosis &pulmonary hypertension not developed. Patients develop erythrocytosis with attendant hyperviscosity &hypertrophic osteoarthropathy with increases risk of risk of: Infective endocarditis (IE), brain abscess, systemic emboli. 2- Transposition of great vessels: Pulmonary artery arises from left ventricle &aorta arises from right ventricle. There is separation of the systemic &pulmonary circulation which is incompatible with life unless there is some shunt through VSD, ASD or PDA. It results from failure of proximal aorta &pulmonary artery to undergo rotation. Even with stable shunting most uncorrected TGA patients still die within first months of life, so they undergo corrective surgery within weeks of birth. Complications of Right-to-left shunts: 1-bypass the lungs, leading to hypoxia and tissue cyanosis (bluish discoloration of the skin and mucous membranes) result because the pulmonary circulation is bypassed and poorly oxygenated venous blood shunts directly into the systemic arterial supply. 2-Right-to-left shunts also allow venous emboli to enter the systemic circulation (paradoxical emboli).  3-Secondary findings in long-standing cyanotic heart disease include clubbing (distal blunting and bulbous enlargement of the tips of the fingers and toes) begins as proliferation of soft tissue of nail bed then it may include bony changes (called hypertrophic osteoarthropathy). The mechanism: chronic hypoxia …systemic vasodilatation…increase blood supply….increases soft tissue proliferation. 4- increased numbers of circulating red blood cells (polycythemia) A cyanotic heart diseases: Left-to-right shunts cause pulmonary volume overload. If the shunt is prolonged, the vasculature responds with medial hypertrophy and increased vascular resistance to maintain normal pulmonary capillary and venous pressures. As pulmonary resistance approaches systemic levels, a right-to-left shunt occurs (Eisenmenger syndrome). Once there is significant pulmonary hypertension, the underlying structural defects are no longer candidates for surgical correction. Eisenmenger syndrome Definition: Is a medical condition that occur due to longstanding, untreated LT to RT shunt of the heart or great vessels (VSD, ASD, PDA), characterized by hypoxemia and cyanosis. Pathophysiology: sequence of events: Increase blood flow and pressure in pulmonary arteries… damage to endothelial cell, intimal proliferation, hypertrophy of the media thrombosis or vasoconstriction… , and small vessel occlusion by narrowing and stiffness of pulmonary blood vessels. the initial vascular changes is reversible but with the time it become permanent, irreversible and unrepairable changes leading to increase vascular resistance and pulmonary hypertension …  When the pulmonary vascular resistance is near, or exceeds, the systemic vascular resistance, the shunt reverses The resultant right to left shunting results in hypoxia and cyanosis Atrial Septal Defect (ASD) ASDs are abnormal, fixed openings in the atrial septum caused by incomplete tissue formation that allows communication of blood between the left and right atria ASDs are usually asymptomatic until adulthood. less likely to close spontaneously (unlike VSDs which most close spontaneously). It is the most common CHD diagnosed in adults. ASDs are usually isolated (not associated with other anomalies), cause volume overload hypertrophy and right ventricle develops. of the right atrium Irreversible pulmonary hypertension develops in less than 10% of patients. Ventricular Septal Defect (VSD) Is the most common congenital cardiac anomaly overall. The clinical outcome depends on VSD size, the clinical outcome ranging from asymptomatic and spontaneous closure if it is small. to fulminant CHF and left to right shunt, then pulmonary hypertension, cyanosis and reversal of the shunt (Eisenmenger syndrome) and may end with death if it is large. So early surgical correction for large size VSD is desirable. VSD are frequently associated with other anomalies, particularly tetralogy of Fallot (TOF)  Reversal shunt occur early &more frequently than ASD, so early surgical correction indicated. 2- Patent ductus arteriosus (PDA): During intrauterine life, ductus arteriosus is a vascular channel between pulmonary artery &aorta, permit flow of blood from pulmonary artery to aorta, bypassing unoxygenated lungs.The ductus normally closes within 1 to 2 days of life. Complete structural obliteration occurs within the first few months of extrauterine life leaving behind the ligamentum arteriosum. When it remains open---left to right shunt i.e oxygenated blood flow from left ventricle to lungs &return to left atrium. Patent Ductus Arteriosus (PDA) 90% of PDAs are isolated defects the remainder are associated with VSD or other cardiac anomalies. Most are initially asymptomatic but produce a Harsh continuous machinery-like heart murmur. Large PDAs cause right-sided volume and pressure overload. 4- Coarctation of aorta: More common in male than female, may associated with sacular aneurysm of CNS occur frequently with Turner"s syndrome. It is morphologically of 2 types: 1- Preductal: In which there is narrowing of aortic isthmus (region between left subclavian &point of entry of ductus arteriosus) which is the source of blood delivered to distal aorta. Right heart perfuse body distal to coarctation---dilated &hypertrophied &pulmonary trunk dilated to accommodate increase blood flow. Clinically: Present in infancy with: Congestive heart failure, Selective cyanosis of lower limbs because of perfusion by poorly oxygenated blood via ductus arteriosus, Femoral pulse weaker than those of upper limbs. 2- Post ductal or adult coarctation: The aorta constricted just distal to the obliterated ductus arteriosus. Collateral flow through intercostal, phrenic &epigastric arteries &supplies blood to distal aorta, Patients not survive neonatal period without surgical correction. Clinically: Present in children &adults, because blood reaching distal aorta come from collateral i.e oxygen contents is normal &selective cyanosis not seen. Hypertension of upper limbs in most cases is due in part to renal hypoperfusion. Systemic blood pressure low &pulses are weak in lower limbs---signs &symptoms of arterial insufficiency e.g intermittent claudication.