Cardiac Pathology: Heart Failure and Ischemic Disease

• Cardiac pathology involves several conditions affecting the heart, including heart failure, ischemic heart disease, carditis, and cardiomyopathy, as well as cardiac tumors.

Heart Failure

• Heart failure can be left-sided or right-sided, each leading to distinct pathological changes.
• Left-sided heart failure leads to congestion and edema in the lungs.
• Gross examination of the lungs reveals they are wet and boggy.
• Hemosiderin pigment accumulates in the lungs, engulfed by macrophages, leading to heart failure cells.
• Right-sided heart failure leads to venous pooling in organs
• In the liver, this causes a "nutmeg" appearance
• It can also affect the spleen called congestive splenomegaly
• Chronic venous congestion can result in Y-gandy bodies, hemosiderin, cysts, and fibrosis in the organs.

Ischemic Heart Disease

• It includes angina and myocardial infarction (MI).
• Angina presents as chest pain, classified as stable, unstable, or variant (Prinzmetal's) angina.
• Stable angina is often uncomplicated, where pain occurs on exertion due to a stable atherosclerotic plaque.
• Variant angina involves vasospasm of coronary arteries.

Unstable Angina

• Unstable angina is more complicated, and can be caused by:
• Aneurysm
• Calcification
• Ulceration
• Thrombosis
• Embolism
• MI is characterized by left-sided chest pain radiating to the jaw or left arm.

Clinical Signs of Ischemic Heart Disease

• Uneasiness
• Nausea
• Vomiting
• Diaphoresis (excessive sweating).

Diagnostics of Myocardial Infarction

• ECG can detect ST-segment elevation (STEMI), indicating the entire muscle wall is affected, or non-ST-segment elevation (NSTEMI), affecting the subendocardial region.
• Cardiac enzyme levels in blood tests are also helpful, where troponin I is useful for detection
• Myoglobin: Appears earliest, peaks fast, falls fastest
• Earliest marker: Heart-fatty acid-binding protein (HFABP)
• Ischemia-modified albumin (IMA) is also useful.
• Lactate dehydrogenase (LDH) ratio flips in the blood after MI. The normal ratio of LDH 2 > LDH 1 in blood reverses when LDH 1 rises due to heart muscle injury.

Autopsy Findings of Myocardial Infarction

• Troponin serves as a marker of reinfarction and is monitored serially, where a rise by 20% indicates reinfarction.
• Autopsy findings vary with time after chest pain:
• 0–30 minutes: Relaxation of myofibrils and mitochondrial swelling is a characteristic feature.
• 30 minutes–4 hours: Vacuolation of the cells and wavy cardiac fibers occur in irreversible cell injury.
• Using triphenyl tetrazolium chloride (TPTC) stain can asses condition <4hrs
• After 4 hours, changes become visible to the naked eye, ranging from occasional dark mottling (4-12 hours) to dark mottling with coagulative necrosis (12-24 hours).
• Microscopic changes include increased neutrophils (1-3 days), macrophages (3-7 days), and early granulation tissue (7-10 days) leading to collagen deposition (10-14 days) and eventually scar formation (>2 months).
• Masson trichrome stain distinguishes muscle from collagen.

Reperfusion Injury

• Characterized by increased free radicals.
• Increased Ca+2 concentration, potentially leading to severe muscle contraction.

Complications of Myocardial Infarctions

• Arrhythmias
• Contractile dysfunction.
• Thrombus formation.
• Cardiac rupture which is highest (5-7 days) before the repaires is set
• Possible aneurysm.
• Papillary muscle dysfunction
• Infarct extension.
• Dressler syndrome (autoimmune pericarditis) occurs about 3 weeks later.

Carditis

• Carditis includes pericarditis(inflammation of the outer membrane surrounding the heart), myocarditis inflammation of the heart, and endocarditis inflammation of the inner lining of the heart.

Pericarditis

• Bread and butter Pericarditis that occurs with rheumatic heart disease
• Serofibrinous pericarditis is characterized by a watery, thready fluid between the parietal and visceral layers of the pericardium.

Myocarditis

• Myocarditis are mostly viral in nature.
• Common viral etiologies are Coxsackie and Herpes virus

Endocarditis

• Endocarditis commonly presents with vegetations typically on the valves
• Common causes are:
• Rheumatic heart disease (RHD)
• Infective endocarditis (IE)
• Non-bacterial thrombotic endocarditis (NBTE)
• Libman-Sacks endocarditis (LSE)

Summary of Vegetations in Endocarditis

• Rheumatic Heart Disease (RHD):
  • Small warty vegetations along the lines of valve closure.
• Infective Endocarditis (IE):
  • Large and bulky vegetations with bits that can fall off.
  • Emboli can occur.
• Non-Bacterial Thrombotic Endocarditis (NBTE):
  • Small and friable vegetations along the lines of closure.
  • Emboli sometimes occur.
• Libman-Sacks Endocarditis (LSE):
  • Vegetations can appear on both sides of the valve and are commonly found on the lower surface.

Rheumatic Heart Disease (RHD)

• Usually caused by Group A beta-hemolytic Streptococcus (S. pyogenes).
• Most at risk are children 5-15 years old.
• 3% of sore throats lead to RHD.
• The mechanism is:
  • Molecular mimicry, where Streptococcus pyogenes mimics heart tissue and leads to a cross reaction and subsequent carditis. Jones criteria:
  • Revised Jones criteria are used to diagnose acute rheumatic fever.

Major Criteria

• Joint (migratory polyarthritis)
• Subcutaneous nodules (painless)
• Erythema marginatum
• Sydenham's chorea
• Carditis Minor Criteria:
  • Clinical: Fever, Polyarthralgia, PR interval prolonged.
  • Lab: Elevated ESR, CRP
• Diagnosis:
  • 2 major criteria
  • 1 major and 2 minor criteria
  • plus supporting evidence of streptococcal infection

Infective Endocarditis (IE)

• Can be caused by native heart valve or Prosthetic heart valve
• Native heart valve can be community-aquired or nosocomia (aureus), Adults that present is by streptococcus
• Under 2months: S. Epidermiidis
• 2+ months S. Epidermidis + S. Aureus
• vegetations: Larger and Bulky.

Revised Dukes Criteria for Diagnosing Infective Endocarditis - Major Criteria: Positive blood cultures and evidence of endocardial involvement. - Minor Criteria: Fever, immunological phenomena, Roth spots, Osler nodes, Janeway lesions, and predisposing factors

Other Criteria

• Definite IE: 2 major criteria, or 1 major and 3 minor, or 5 minor criteria.
• Common bacteria: streptococci, staphylococci, or enterococci
• Valves most commonly affected:
  • Mitral valve is most common overall
  • Drug users can develop it on right side heart valves.

Non-Bacterial Thrombotic Endocarditis (NBTE)

• Often seen in patients with advanced cancer
• Can be associated with conditions like acute promyelocytic leukemia
• Characterized by the presence of small clots on heart valves

Libman-Sacks Endocarditis (LSE)

• Often seen in patients with Systemic Lupus Erythematosus (SLE)

Cardiomyopathy

• Cardiomyopathy is disease of of the heart muscle
• Dilated Cardiomyopathy (DCM), Hypertrophic Obstructive Cardiomyopathy, Restrictive Cardiomyopathy, Arrhythmogenic Right Ventricular Cardiomyopathy are common

Dilated Cardiomyopathy (DCM)

• Characterized by dilation of all four chambers and hypertrophy of the fibers.
• Idiopathic or genetic causes are the most common culprits.
• Genetic: titin is the largest protein.
• Causes: Alcohol, Anthracyclines, Selenium deficiency (China), Peripartum.

Takotsubo Cardiomyopathy

• Variant of DCM, is usually tied to Broken Hearts!
• Broken heart releases catecholamines that cause ventricular dilation, in the LV
• Usually due to high emotional Stress

Arrhythmogenic Right Ventricular Cardiomyopathy

• A genetic disorder.
• RV is infiltrated by fat.
• Syndrome:
• Naxos(Woolly hair)
• Plakoglobin(Palmar plantar keratoderma)
• Desmosomes is defective

Hypertrophic Obstructive Cardiomyopathy

• HOCM is characterized by B myosin heavy chain defect.
• It is AD inheritance pattern.
• Characterized by hypertrophy of the Interventricular system.
• IVS > 1.5 on LV wall thickness results in sudden death/collapse in athletes.
• LV takes a banana Shape

Restrictive Cardiomyopathy

• Results in Diastolic dysfunction of the heart muscle.
• Inadequate fill
• Can be caused by Amyloid deposition.

Cardiac Tumors

• Metastasis is most common, often from the central nervous system.
• Primary cardiac tumors are rare.
• In adults:
  • Most common benign tumor is myxoma.
  • Most common malignant tumor is angiosarcoma.
• In children:
  • Most common benign tumor is rhabdomyoma.
  • Most common malignant tumor is rhabdomyosarcoma.
• The most common valve tumor is papillary fibroelastoma, which looks like sea anemone.
• Myxoma is like a tumor.
• Rhabdomyoma are common in children
• Myxoma is common in adults, and are commonly found in LA
• Spider Cells of Lpidic Cells leads to Empty spaces.
• PAS shows = Glycogen
• Carney complex is associated with rhabdomyoma.