Heart Quiz

The Heart

• The human heart is a vital organ, pumping blood through the body, crucial for oxygen and nutrient delivery.
• Worldwide, cardiovascular disease is the leading cause of deaths, with over 610,000 deaths annually in the United States alone.

Cardiac Structure and Specializations

• Heart weight varies with body habitus, normally 0.4% to 0.5% of body weight.
• Increased heart weight or ventricular thickness indicates hypertrophy.
• Enlarged chamber size implies dilation.
• Cardiomyocytes are responsible for heart's pumping function.
• Atrial cardiomyocytes contain granules storing atrial natriuretic peptide.
• Ventricular cardiomyocytes contain B-type natriuretic peptide.
• These hormones promote arterial vasodilation and renal salt/water removal.

Cardiac Valves

• Four valves (tricuspid, pulmonary, mitral, and aortic) maintain unidirectional blood flow.
• Atrioventricular valves (tricuspid and mitral) depend on leaflets, tendinous cords, and papillary muscles.
• Semilunar valves (aortic and pulmonary) depend on cuspal attachments.

Cardiac Conduction System

• Electrical impulses initiate cardiac contraction via specialized myocytes.
• SA node (sinoatrial node) is the pacemaker (60-100 beats/min).
• AV node (atrioventricular node) acts as a gatekeeper by delaying impulse transmission to ventricles.

Blood Supply

• Myocardial energy production relies heavily on oxidative phosphorylation.
• Coronary arteries supply oxygenated blood to myocardium.

Cardiac Regeneration

• Potential exists to regenerate damaged myocardium by inducing cardiac regeneration in vivo or implanting stem cells.
• However, adult mammalian myocardium has a limited replicative potential.

Effects of Aging on the Heart

• Several changes occur with age, including changes to chamber sizes and valves.
• Increased subepicardial fat, brown atrophy and decreased cardiomyocyte number, and accumulation of amyloid in the elderly heart.
• These changes contribute to cardiovascular diseases more prevalent in the aging population.

Overview of Cardiac Pathophysiology

• Heart failure (CHF) is a condition where the heart cannot adequately pump blood to meet body's demands.
• CHF often arises from prior chronic overload (e.g., valve disease or hypertension) or acute events (e.g., MI).
• Main mechanisms of a "broken" heart include: pump failure, obstruction to flow, regurgitant flow, shunted flow, conduction disorders, and rupture.

Heart Failure

• Over one-half of patients with CHF die within 5 years of diagnosis.
• One out of every nine deaths in the United States is directly linked to CHF.
• CHF is characterized by inadequate cardiac pumping to meet peripheral tissue demands, coupled with increased venous congestion.

Left-Sided Heart Failure

• Is most commonly caused by ischemic heart disease, hypertension, and valvular diseases.
• Passive congestion and resultant blood backing-up in the pulmonary circulation are hallmark signs of left-sided heart failure.

Right-Sided Heart Failure

• Is frequently a consequence of left-sided heart failure.
• Primarily occurs in conditions/disorders affecting the lungs and/or pulmonary vasculature.

Ischemic Heart Disease

• IHD is a group of diseases resulting from an imbalance between myocardial oxygen supply and demand.
• Atherosclerosis is the main cause in over 90% of cases.
• Clinically significant plaques in coronary arteries limit blood flow, leading to myocardial ischemia.

Angina Pectoris

• Recurrent chest discomfort resulting from transient myocardial ischemia.
• Different forms exist, distinguished by provocation factors and time course.

Acute Myocardial Infarction (MI)

• Ischemia sufficient to cause cell death, often triggered by a superimposed thrombus.
• Most patients experience crushing chest pain, radiating pain to the left arm, jaw, or back; other symptoms include profuse sweating, nausea, and shortness of breath.
• Early diagnosis and intervention can improve outcomes.

Myocardial Response to Ischemia

• Early Biochemical Changes, involving ATP depletion, lactate accumulation, and progressive loss of myocardial viability.
• Cellular/structural changes follow, mirroring loss of energy.

Infarct Modification by Reperfusion

• Restoration of blood flow, using therapies like thrombolysis, angioscopy, or bypass surgery, can salvage some ischemic myocardium.
• Reperfusion may, however, induce secondary harm.

Clinical Features of MI

• Diagnosis uses clinical symptoms, laboratory tests, and specific ECG changes.
• Early intervention plays a key role in limiting infarct expansion and cellular/tissue damage.

Other Causes of Myocardial Disease

• Many conditions, such as cardiotoxic drugs, radiation exposure, and infections (myocarditis), result in myocardial damage.

Pericardial Disease

• Pericardial disease involves problems with the pericardial sac, which surrounds the heart.
• Fluid accumulation (effusion), inflammation (pericarditis), and fibrous scar formation (constrictive pericarditis) are key markers.

Tumours of the Heart

• Primary heart tumors (e.g., myxomas, lipomas, fibromas, rhabdomyomas) are rarely malignant.
• Metastatic tumors (likely starting from other locations) are more common.

Cardiac transplantation

• Cardiac transplantation is a life-saving therapy for end-stage heart failure, but complicated by risks like rejection and vasculopathy.

Cardiac Devices

• Ventricular assist devices (VAD) allow for short- or long-term mechanical support in individuals with advanced heart failure, awaiting a transplant.

Arrhythmias

• Arrhythmias are abnormal cardiac rhythms, varying from slow (bradycardia) to fast (tachycardia) to erratic rhythms.
• Several genetic causes (including channelopathies) are implicated.
• IHD can produce abnormal myocardial electrical conduction patterns.

Cardiomyopathies

• Cardiomyopathies are heart muscle diseases, categorized as dilated (predominantly systolic dysfunction), hypertrophic (predominantly diastolic dysfunction), and restrictive (mainly impaired diastolic filling).
• Genetic factors are often responsible.

Myocarditis

• Inflammation of heart muscle triggered by infections (most commonly viral).
• Clinical presentation varies from asymptomatic to severe heart failure.

Test your knowledge on the characteristics and complications of heart failure and various forms of cardiomyopathy. This quiz covers essential concepts including left ventricular dysfunction, neurohumoral stimulation, and common heart diseases. Challenge yourself with questions related to diagnosis and management in cardiovascular health.