Cardiovascular System — MCQs
Which part of the heart is located in the anterosuperior sternal region?
The largest component of the total peripheral resistance is due to:
Which condition is indicated by ST segment elevation in leads V1-V4?
Which of the following structures in the heart are known for their rapid conduction of electrical impulses?
Which of the following findings is seen in pericardial tamponade?
All of the following arteries are common sites of occlusion by a thrombus except:
A child presented at 10 weeks with recurrent episode of pneumonia and failure to thrive. X-ray shows cardiomegaly & pulmonary plethora. What is the diagnosis?
Which of the following is the most common congenital cardiac malformation?
The right coronary artery supplies blood to all of the following structures, except?
Ducts of Bellini are present in:
Cardiovascular System Indian Medical PG Practice Questions and MCQs
Question 1: Which part of the heart is located in the anterosuperior sternal region?
- A. Right atrium and auricle.
- B. Left atrium.
- C. Left ventricle.
- D. Right ventricle. (Correct Answer)
Explanation: ***Right ventricle*** - The **right ventricle** forms the **most anterior part of the heart**, located directly behind the sternum and costal cartilages [1]. - Its position explains why **sternal precordial leads** (e.g., V1, V2) on an ECG primarily reflect right ventricular activity [1]. *Right atrium and auricle* - While part of the right atrium is anterior, the **right ventricle is significantly more anterior** and occupies the majority of the anterosuperior sternal region [1]. - The **right auricle** is a small, anterior appendage, but the broader chamber occupying this region is the ventricle [1]. *Left atrium* - The **left atrium** is the **most posterior chamber of the heart**, forming the base [1]. - It lies near the esophagus, making it susceptible to compression by an enlarged left atrium. *Left ventricle* - The **left ventricle** forms the **apex of the heart** and is located primarily on the **left and inferior** aspects. - It is not the most anterior structure; the right ventricle is positioned anteriorly to it [1].
Question 2: The largest component of the total peripheral resistance is due to:
- A. Venules
- B. Arterioles (Correct Answer)
- C. Capillaries
- D. Precapillary sphincters
Explanation: ***Arterioles*** - **Arterioles** are the primary site of **resistance** in the cardiovascular system due to their relatively small diameter and the significant ability of their **smooth muscle** walls to constrict or dilate. - This resistance plays a crucial role in regulating **blood flow** to various organs and contributes to **mean arterial pressure**. *Venules* - **Venules** are primarily involved in collecting blood from capillaries and have relatively low resistance compared to arteries and arterioles. - While they contribute to capacitance, their impact on **total peripheral resistance** is minimal. *Capillaries* - Although **capillaries** have very small diameters, their sheer number in parallel reduces the overall resistance of the capillary bed. - The primary function of capillaries is **exchange** of nutrients and waste, not primarily resistance. *Precapillary sphincters* - **Precapillary sphincters** control blood flow *into* capillaries from arterioles, acting as gates. - While they regulate flow to specific capillary beds, they are not the largest *component* of total systemic resistance; the **arterioles themselves** are.
Question 3: Which condition is indicated by ST segment elevation in leads V1-V4?
- A. Posterior myocardial infarction
- B. Lateral myocardial infarction
- C. Anterior myocardial infarction (Correct Answer)
- D. Inferior myocardial infarction
Explanation: ***Anterior myocardial infarction*** - **ST segment elevation** in leads **V1-V4** is indicative of an infarction in the **anterior wall** of the left ventricle [1]. - These leads correspond to the distribution of the **left anterior descending (LAD) coronary artery**, which supplies the anterior wall and septum [2]. *Posterior myocardial infarction* - This typically presents with **ST depression** in **V1-V4**, along with tall R waves and prominent T waves in the same leads, due to a reciprocal change. - Definitive diagnosis requires **posterior leads (V7-V9)**, which would show ST elevation. *Lateral myocardial infarction* - Characterized by **ST elevation** in leads **I, aVL, V5, and V6**, reflecting ischemia in the lateral wall of the left ventricle [1]. - These leads are supplied by the **circumflex artery** or a diagonal branch of the LAD. *Inferior myocardial infarction* - Identified by **ST elevation** in leads **II, III, and aVF**, indicating involvement of the inferior wall [1]. - This is typically caused by occlusion of the **right coronary artery (RCA)** or a dominant circumflex artery.
Question 4: Which of the following structures in the heart are known for their rapid conduction of electrical impulses?
- A. Sinoatrial (SA) node
- B. Atrioventricular (AV) node
- C. His bundle
- D. Purkinje fibers (Correct Answer)
Explanation: ***Correct: Purkinje fibers*** - **Purkinje fibers** have the **fastest conduction velocity** among all cardiac tissues, approximately **4 m/s** - These specialized myocardial fibers ensure **rapid and synchronized depolarization of the ventricles**, allowing for efficient and coordinated ventricular contraction - Their rapid conduction is essential for simultaneous contraction of ventricular myocardium from apex to base *Incorrect: Sinoatrial (SA) node* - The SA node is the natural **pacemaker** of the heart, initiating electrical impulses at a rate that determines heart rate - However, its conduction velocity is **very slow** (~0.05 m/s), much slower than Purkinje fibers - Its role is impulse generation, not rapid conduction *Incorrect: Atrioventricular (AV) node* - The AV node has the **slowest conduction velocity** in the heart (~0.05 m/s) - It **delays electrical impulses** from the atria to the ventricles (AV delay ~0.1 seconds) - This delay allows for **complete ventricular filling** before ventricular contraction begins *Incorrect: His bundle* - The bundle of His transmits impulses from the AV node to the bundle branches - While faster than the AV node (~1-1.5 m/s), it is still **significantly slower than Purkinje fibers** - Its conduction velocity is intermediate between the AV node and Purkinje fibers
Question 5: Which of the following findings is seen in pericardial tamponade?
- A. Beck's triad
- B. Kussmaul sign
- C. Pulsus paradoxus (Correct Answer)
- D. All of the options
Explanation: ***Pulsus paradoxus*** - This is an **abnormally large decrease** in systolic blood pressure (>10 mmHg) and pulse wave amplitude during inspiration. - It occurs due to compromised ventricular filling caused by **increased pericardial pressure** in tamponade [1]. *Beck's triad* - Beck's triad (hypotension, jugular venous distention, and muffled heart sounds) are **signs/symptoms** of pericardial tamponade, not a finding in the same way pulsus paradoxus is [1]. - This clinical triad points towards the diagnosis but does not describe a physiological finding as specifically as pulsus paradoxus. *Kussmaul sign* - The Kussmaul sign is a paradoxical **increase** in jugular venous pressure (JVP) during inspiration. - While it indicates impaired right ventricular filling, it is classically seen in **constrictive pericarditis** and severe right heart failure, not typically in pericardial tamponade [2]. *All of the options* - This option is incorrect because Kussmaul sign is typically associated with **constrictive pericarditis** rather than pericardial tamponade [2]. - While Beck's triad is characteristic of tamponade, pulsus paradoxus is a specific hemodynamic finding seen in this condition [1].
Question 6: All of the following arteries are common sites of occlusion by a thrombus except:
- A. Posterior interventricular
- B. Circumflex
- C. Marginal (Correct Answer)
- D. Anterior interventricular
Explanation: ***Marginal*** - The **marginal arteries** are typically small and supply a smaller portion of the right ventricle, making them less likely sites for **major clinical occlusion** compared to larger, more critical coronary vessels. - While occlusion can occur, it usually causes less extensive damage and is therefore **less common** as a primary site of acute thrombus-related myocardial infarction. *Posterior interventricular* - The **posterior interventricular artery (PDA)** is a major coronary artery, responsible for supplying the posterior walls of the ventricles and the posterior one-third of the interventricular septum. - Occlusion of the PDA, often a branch of the right coronary artery (RCA) or circumflex artery, can lead to **significant infarction** in these critical areas, making it a common site of thrombus formation. *Circumflex* - The **circumflex artery (Cx)** is a major branch of the left main coronary artery that supplies the left atrium and the posterior and lateral walls of the left ventricle. - Occlusion of the circumflex artery can result in **lateral or posterior myocardial infarction**, making it a frequent site for thrombus formation. *Anterior interventricular* - The **anterior interventricular artery (LAD)**, also known as the left anterior descending artery, is the most common site of coronary artery occlusion. - It supplies the anterior wall of the left ventricle and the anterior two-thirds of the interventricular septum, and its occlusion is often referred to as the **"widowmaker"** due to the extensive damage and high mortality associated with it.
Question 7: A child presented at 10 weeks with recurrent episode of pneumonia and failure to thrive. X-ray shows cardiomegaly & pulmonary plethora. What is the diagnosis?
- A. VSD (Correct Answer)
- B. TOF
- C. Patent foramen ovale
- D. ASD
Explanation: ***VSD*** - **Ventricular septal defect (VSD)** is the most common cause of this presentation in early infancy (symptoms typically appear at **6-10 weeks** of age). - Large VSDs cause significant **left-to-right shunt** leading to pulmonary overcirculation, resulting in **recurrent pneumonia** and **failure to thrive**. - **Cardiomegaly** (due to volume overload of left atrium and ventricle) and **pulmonary plethora** (increased pulmonary vascular markings) on X-ray are classic findings. - The infant may also present with tachypnea, feeding difficulties, and poor weight gain. *TOF* - **Tetralogy of Fallot (TOF)** is a **cyanotic heart defect** with right-to-left shunt, presenting with cyanosis and hypoxic spells, not recurrent pneumonia. - X-ray shows **boot-shaped heart** and **pulmonary oligemia** (decreased pulmonary vascular markings), not pulmonary plethora. - Does not typically cause failure to thrive in the same manner as acyanotic left-to-right shunt lesions. *Patent foramen ovale* - A **patent foramen ovale (PFO)** is a normal variant in infants and typically remains **asymptomatic**. - Does not cause significant hemodynamic shunting in the absence of elevated right atrial pressure. - Does not cause **cardiomegaly**, **pulmonary plethora**, recurrent pneumonia, or failure to thrive. *ASD* - An **atrial septal defect (ASD)** also causes left-to-right shunt with pulmonary plethora, but the shunt develops **gradually** over time. - ASD typically presents **later in childhood or adulthood** with milder symptoms (fatigue, exercise intolerance) due to lower pressure gradient across atria. - **Recurrent pneumonia and failure to thrive at 10 weeks** are uncommon with isolated ASD, as the hemodynamic changes are less pronounced in early infancy compared to VSD. - When symptomatic in infancy, large ASDs present later (around 6 months to 1 year) rather than at 10 weeks.
Question 8: Which of the following is the most common congenital cardiac malformation?
- A. Persistent truncus arteriosus (PTA)
- B. Common ventricle (CV)
- C. Ventricular septal defect (VSD) (Correct Answer)
- D. Atrial septal defect (ASD)
Explanation: ***Ventricular septal defect (VSD)*** - VSDs are the **most common congenital heart defect**, accounting for approximately 25-30% of all congenital cardiac malformations. - They involve a **hole in the septum** separating the left and right ventricles, leading to a left-to-right shunt. *Persistent truncus arteriosus (PTA)* - PTA is a rare congenital heart defect where a **single arterial trunk** arises from the heart, supplying both systemic and pulmonary circulation. - Its incidence is much **lower than VSD**, representing less than 1% of congenital heart defects. *Common ventricle (CV)* - A common ventricle, also known as **single ventricle**, is a complex and rare congenital defect where only one functional ventricle is present. - It is a **severe malformation** and much less common than VSD. *Atrial septal defect (ASD)* - ASDs are congenital heart defects involving a **hole in the wall between the atria** of the heart. - While relatively common, ASDs are **less frequent than VSDs**, accounting for about 5-10% of congenital heart defects.
Question 9: The right coronary artery supplies blood to all of the following structures, except?
- A. Posterior wall of left ventricle
- B. SA node
- C. Anterior 2/3 of ventricular septum (Correct Answer)
- D. AV node
Explanation: ***Anterior 2/3 of ventricular septum*** - The **anterior two-thirds of the interventricular septum** is primarily supplied by the **septal branches of the left anterior descending artery** (LAD) [1], a branch of the left coronary artery. - Therefore, the right coronary artery does not typically supply this region. *SA node* - The **SA node** (sinoatrial node) is the heart's natural pacemaker and receives its blood supply from the **right coronary artery** in about 60% of individuals. - Occlusion of the RCA can lead to symptomatic **bradycardia** or **SA node dysfunction**. *AV node* - The **AV node** (atrioventricular node), crucial for coordinating ventricular contraction, is supplied by the **right coronary artery** in approximately 90% of individuals [1]. - Infarcts in the RCA territory can manifest as various degrees of **heart block**. *Posterior wall of left ventricle* - The **posterior wall of the left ventricle** is predominantly supplied by the **posterior descending artery (PDA)**, which in about 80% of people, is a terminal branch of the **right coronary artery** [1]. - This supply is vital for the contractile function of the left ventricle's posterior aspect.
Question 10: Ducts of Bellini are present in:
- A. Pancreas
- B. Liver
- C. Kidney (Correct Answer)
- D. Salivary gland
Explanation: ***Kidney*** - The Ducts of Bellini, also known as **large papillary collecting ducts**, are the terminal portions of the collecting duct system in the kidney. - They are located in the **renal medulla**, particularly within the renal papillae, and drain urine into the minor calyces. *Pancreas* - The pancreas is involved in **digestion** and hormone production (e.g., insulin), not urine formation. - Its duct system includes the **main pancreatic duct (Wirsung's duct)** and accessory pancreatic duct. *Liver* - The liver's primary functions are **metabolism**, detoxification, and bile production. Its duct system consists of **bile ducts**, which transport bile, not urine [1], [2]. - Its duct system consists of **bile ducts**, which transport bile, not urine. *Salivary gland* - Salivary glands produce **saliva** and have their own unique duct systems (e.g., Wharton's duct, Stensen's duct). - These glands are part of the digestive system and are not involved in renal function.
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