Cardiovascular System Practice Questions

Q: Distributive shock is described by which of the following patterns of cardiovascular responses? 1. Vasodilation 2. Reduced peripheral vascular resistance 3. Inadequate 'afterload' 4. Low cardiac output Select the correct answer using the code given below.

1, 2 and 3. ***1, 2 and 3*** - Distributive shock is characterized by **widespread vasodilation** (1), leading to a significant **reduction in peripheral vascular resistance/SVR** (2). - The reduced vascular resistance causes **inadequate afterload** (3) on the heart, as afterload is determined by SVR. - Cardiac output is typically **normal or elevated** in early distributive shock as the heart compensates for the low SVR, so statement 4 is NOT characteristic. - Classic examples include septic shock, anaphylactic shock, and neurogenic shock. *1, 2 and 4* - While **vasodilation** (1) and **reduced peripheral vascular resistance** (2) are correct, **low cardiac output** (4) is NOT a defining feature of distributive shock. - In distributive shock, cardiac output is often elevated in the hyperdynamic phase as the heart compensates for decreased SVR. - Low cardiac output is more characteristic of cardiogenic or hypovolemic shock. *1, 3 and 4* - **Vasodilation** (1) and **inadequate afterload** (3) are correct features, but **low cardiac output** (4) is incorrect. - Distributive shock typically presents with normal or increased cardiac output, not decreased. - This combination incorrectly includes low CO while missing the reduced peripheral vascular resistance (2). *2, 3 and 4* - **Reduced peripheral vascular resistance** (2) and **inadequate afterload** (3) are correct, but this option misses the fundamental mechanism of **vasodilation** (1). - Additionally, **low cardiac output** (4) is not a defining characteristic of distributive shock. - Without mentioning vasodilation, the underlying pathophysiology is incomplete.

Q: Which one of the following statements is not correct about fetal circulation?

Umbilical artery carries oxygenated blood to the fetus. ***Umbilical artery carries oxygenated blood to the fetus*** - This statement is incorrect because the **umbilical arteries** carry **deoxygenated blood** and waste products away from the fetus to the placenta. - Oxygenated blood is carried *to* the fetus by the **umbilical vein**. *Umbilical artery carries deoxygenated fetal blood to the placenta* - This statement is correct. The **umbilical arteries** are responsible for transporting **deoxygenated blood** and metabolic waste products from the fetal circulation back to the placenta for exchange with the maternal blood. - This is a key component of the fetoplacental circulation. *Two umbilical arteries and one umbilical vein traverse through the fetus and placenta* - This statement is correct. The **umbilical cord** typically contains **two umbilical arteries** and one **umbilical vein**. - This arrangement facilitates efficient nutrient and gas exchange between the mother and fetus. *Umbilical vein carries oxygenated blood to the fetus* - This statement is correct. The **umbilical vein** carries **oxygenated blood** rich in nutrients from the placenta to the fetus. - This is the main conduit for essential substances required for fetal growth and development.

Q: Non-cardiac causes of raised central venous pressure include all of the following except:

Hyper-volemia. **IMPORTANT NOTE:** This question as originally presented is medically problematic because **hypervolemia is actually a NON-CARDIAC cause** of elevated CVP. All four options listed are non-cardiac causes, making this question flawed. However, if this represents the original UPSC-CMS-2013 answer key, the intended distinction may have been between **systemic/volume-related causes** versus **mechanical/obstructive causes**. ***Hypervolemia (Marked as answer)*** - Hypervolemia (fluid overload) is technically a **non-cardiac, systemic cause** of elevated CVP, not a cardiac cause - It increases CVP by increasing **circulating blood volume** and venous return, without primary cardiac dysfunction - True **cardiac causes** would include right heart failure, tricuspid regurgitation, cardiac tamponade, or constrictive pericarditis - If this was the intended answer, the distinction may be: hypervolemia is a **systemic/volume cause** while the others are **mechanical/obstructive causes** *Abdominal compartment syndrome* - Increases **intra-abdominal pressure** which transmits to the thorax - Mechanically compresses the **inferior vena cava**, impeding venous return - This is clearly a **non-cardiac, mechanical cause** of elevated CVP *Positive pressure ventilation* - Increases **intrathoracic pressure** during mechanical ventilation - Directly opposes venous return to the right atrium - This is a **non-cardiac, mechanical cause** of elevated CVP *Tension pneumothorax* - Causes severe increase in **intrathoracic pressure** from trapped air - Compresses the **vena cavae** and impedes venous return - This is a **non-cardiac, mechanical/obstructive cause** of elevated CVP **Clinical Pearl:** When evaluating elevated CVP, distinguish between cardiac causes (right heart failure, tamponade), mechanical causes (tension pneumothorax, positive pressure ventilation), obstructive causes (SVC syndrome), and volume-related causes (hypervolemia).

Q: The central venous pressure (CVP) is low in

Tension pneumothorax. ***Tension pneumothorax*** - A **tension pneumothorax** causes compression of the **superior and inferior vena cava** due to increased intrathoracic pressure and mediastinal shift. - This compression **impairs venous return** to the right atrium, leading to **decreased central venous pressure (CVP)**. - Despite elevated intrathoracic pressure, the net effect is **reduced venous return and low CVP**, along with hypotension and cardiac compromise. - This is a life-threatening emergency requiring immediate needle decompression. *Acute left ventricular failure* - In **acute left ventricular failure**, the left ventricle fails to pump blood effectively, causing backup into the pulmonary circulation. - However, the **right ventricle continues to pump** blood into the pulmonary circulation, leading to **increased right atrial pressure and elevated CVP**. - Patients typically present with **elevated CVP** along with pulmonary edema and dyspnea. *Massive pulmonary embolism* - A **massive pulmonary embolism** causes acute increase in **pulmonary vascular resistance** and right ventricular afterload. - The right ventricle becomes acutely strained and dilated, leading to **elevated right atrial pressure and increased CVP**. - Clinical features include hypotension, tachycardia, and jugular venous distension indicating high CVP. *Pericardial effusion* - A **pericardial effusion** causing **cardiac tamponade** compresses all cardiac chambers and restricts ventricular filling. - This leads to **equalization of diastolic pressures** in all chambers and **markedly elevated CVP**. - Classic Beck's triad includes hypotension, muffled heart sounds, and **jugular venous distension** (elevated CVP).

Q: What is the function of the umbilical artery in fetal circulation?

Carry deoxygenated blood from the fetus to the placenta. ***Carry deoxygenated blood from the fetus to the placenta*** - The **umbilical arteries** are responsible for transporting **deoxygenated blood** and waste products away from the fetal circulation to the placenta. - There are typically **two umbilical arteries** that branch off the internal iliac arteries of the fetus. *Provide nutrients* - **Nutrient delivery** to the fetus is primarily a function of the **umbilical vein**, which carries oxygenated and nutrient-rich blood from the placenta. - The umbilical arteries carry metabolic waste products away from the fetus, not nutrients to it. *None of the options* - This option is incorrect because one of the provided options accurately describes the function of the umbilical artery. - The specific role of the umbilical artery is distinct from other fetal circulatory components. *Carry oxygenated blood from the placenta to the fetus* - This function is performed by the **umbilical vein**, which brings **oxygen-rich blood** and nutrients from the placenta to the fetus. - The umbilical arteries carry blood in the opposite direction and with a different oxygenation status.

Q: Which among the following organs has the least arteriovenous oxygen difference?

Kidney. ***Kidney*** - The **kidney** has the lowest arteriovenous oxygen difference among these organs because its metabolic activity, relative to its blood supply, is designed for filtration rather than high oxygen extraction for work. - A significant portion of the kidney's oxygen consumption is related to **active transport** and **reabsorption**, but its unusually high blood flow (about 20-25% of cardiac output) ensures that the oxygen content of venous blood remains high. *Liver* - The liver receives a **dual blood supply** (hepatic artery and portal vein) and is highly metabolically active due to its roles in synthesis, detoxification, and nutrient processing, leading to a substantial oxygen extraction and thus a larger arteriovenous oxygen difference. - It has a significant oxygen demand for its numerous physiological functions, resulting in a lower oxygen content in its venous outflow compared to arterial blood. *Skin* - Skin blood flow is highly variable and plays a crucial role in **thermoregulation** in addition to metabolic needs. - While its baseline metabolic rate is moderate, its oxygen extraction can vary, but generally, it has a larger arteriovenous oxygen difference due to the oxygen demand of its various cellular layers and structures. *Brain* - The **brain** has a consistently high metabolic rate and continuous oxygen demand, consuming about 20% of the body's total oxygen at rest. - This consistent and high demand for oxygen results in a relatively large arteriovenous oxygen difference as it extracts a significant portion of oxygen from the arterial blood.

Q: Blood pressure changes in radial artery were measured. Which of the following is the reason for initial rise in BP while performing Valsalva maneuver?

Increase in aortic pressure. ***Increase in aortic pressure*** - During the initial phase (Phase I) of the Valsalva maneuver, the sudden **increase in intrathoracic pressure** is transmitted directly to the aorta and other large arteries. - This transient increase in external pressure on the great vessels directly causes a brief **rise in aortic blood pressure** before other compensatory mechanisms take effect. *Increase in Left ventricular volume* - The Valsalva maneuver actually **decreases left ventricular volume** over time due to reduced venous return. - An increase in left ventricular volume would typically lead to a sustained increase in cardiac output and blood pressure, which is not what is observed initially during the Valsalva maneuver. *Increase in Left ventricular pressure* - While increased intrathoracic pressure can transiently affect left ventricular pressure, the initial blood pressure rise is primarily due to direct compression of the **aorta and systemic arteries**, not an intrinsic increase in myocardial contractility or ventricular filling pressure. - Ultimately, the Valsalva maneuver generally leads to a decrease in **left ventricular preload** and subsequent decrease in stroke volume during the prolonged straining phase. *Decrease in aortic pressure* - The graph clearly shows an **initial spike in mean aortic pressure** (Phase I) at the onset of the Valsalva maneuver. - A decrease in aortic pressure is characteristic of the later part of the straining phase (Phase II) due to **reduced cardiac output**.

Q: Windkessel effect is not shown by which of the following vessel?

Radial. ***Radial*** - The **radial artery** is a muscular artery, and these vessels primarily regulate blood flow and pressure through vasoconstriction and vasodilation, rather than storing elastic energy. - While all arteries have some elasticity, the **Windkessel effect** is most prominent in large elastic arteries, which are structurally different from muscular arteries like the radial artery. *Renal* - The **renal artery** is a highly compliant, distensible artery that assists in dampening pulsatile flow and ensuring continuous, stable perfusion to the kidneys. - As a major artery off the aorta, it contributes to the **Windkessel effect** by accommodating changes in pressure during the cardiac cycle. *Aorta* - The **aorta** is the primary vessel demonstrating the **Windkessel effect** due to its high elasticity and large diameter. - During systole, it stretches and stores a significant volume of blood, releasing it during diastole to maintain a continuous flow. *Abdominal* - The **abdominal aorta** is a large elastic artery that, like the thoracic aorta, is crucial for expressing the **Windkessel effect**. - Its elastic recoil during diastole helps to sustain blood flow to the lower body and abdominal organs.

Q: If the contractility of the heart is decreased, which of the following is seen ?

Decreased stroke volume. ***Decreased stroke volume*** - A decrease in the **contractility** of the heart directly reduces the force of myocardial contraction. - This weaker contraction results in less blood being ejected from the ventricle per beat, leading to a **decreased stroke volume**. *Increased ejection fraction* - **Ejection fraction** is the percentage of blood ejected from the ventricle with each beat, calculated as (stroke volume / end-diastolic volume) x 100. - When contractility decreases, **stroke volume** decreases, which would typically lead to a *decreased* ejection fraction, not an increased one. *Increased stroke work* - **Stroke work** is a measure of the work done by the ventricle to eject blood, and it depends on both stroke volume and aortic pressure. - With decreased contractility, **stroke volume** falls, which would *decrease* the stroke work, assuming afterload remains constant. *Increased cardiac output* - **Cardiac output** is the product of stroke volume and heart rate (CO = SV x HR). - Since decreased contractility leads to a **decreased stroke volume**, without a compensatory increase in heart rate, cardiac output would *decrease*, not increase.

Q: What is the primary mechanism for maintaining constant cerebral blood flow despite changes in systemic blood pressure?

Myogenic autoregulation. ***Myogenic autoregulation*** - **Myogenic autoregulation** is the intrinsic ability of vascular smooth muscle to contract when stretched by increased blood pressure, thereby maintaining a constant cerebral blood flow. - This mechanism operates within a specific range of mean arterial pressures (typically **60-150 mmHg**) to prevent both hypoperfusion and hyperperfusion of the brain. *Endothelial factors* - Endothelial cells release various vasoactive substances like **nitric oxide** and **endothelin**, which influence vascular tone. - While important for local blood flow regulation, these factors play a secondary role to myogenic autoregulation in maintaining constant cerebral blood flow against systemic pressure changes. *Baroreceptor reflex* - The **baroreceptor reflex** primarily controls systemic blood pressure by regulating heart rate and peripheral vascular resistance. - It does not directly regulate cerebral blood flow stability in response to systemic pressure changes; its main role is to stabilize the overall systemic arterial pressure. *Metabolic control* - **Metabolic control** regulates cerebral blood flow in response to the brain's metabolic demands, primarily by sensing local concentrations of **CO2**, **pH**, and **oxygen**. - While essential for matching blood supply to neuronal activity, it is not the primary mechanism for maintaining cerebral blood flow despite changes in systemic blood pressure.

Question 1

Distributive shock is described by which of the following patterns of cardiovascular responses?

1. Vasodilation
2. Reduced peripheral vascular resistance
3. Inadequate 'afterload'
4. Low cardiac output

Select the correct answer using the code given below.

Accepted Answer

1, 2 and 3

Answer

1, 2 and 4

Answer

1, 3 and 4

Answer

2, 3 and 4

Question 2

Which one of the following statements is not correct about fetal circulation?

Accepted Answer

Umbilical artery carries oxygenated blood to the fetus

Answer

Umbilical artery carries deoxygenated fetal blood to the placenta

Answer

Two umbilical arteries and one umbilical vein traverse through the fetus and placenta

Answer

Umbilical vein carries oxygenated blood to the fetus

Question 3

Non-cardiac causes of raised central venous pressure include all of the following except:

Accepted Answer

Hyper-volemia

Answer

Abdominal compartment syndrome

Answer

Positive pressure ventilation

Answer

Tension pneumothorax

Question 4

The central venous pressure (CVP) is low in

Accepted Answer

Tension pneumothorax

Answer

Massive pulmonary embolism

Answer

Acute left ventricular failure

Answer

Pericardial effusion

Question 5

What is the function of the umbilical artery in fetal circulation?

Accepted Answer

Carry deoxygenated blood from the fetus to the placenta

Answer

Provide nutrients

Answer

None of the options

Answer

Carry oxygenated blood from the placenta to the fetus

Question 6

Which among the following organs has the least arteriovenous oxygen difference?

Accepted Answer

Kidney

Answer

Liver

Answer

Skin

Answer

Brain

Question 7

Blood pressure changes in radial artery were measured. Which of the following is the reason for initial rise in BP while performing Valsalva maneuver?

Accepted Answer

Increase in aortic pressure

Answer

Increase in Left ventricular volume

Answer

Increase in Left ventricular pressure

Answer

Decrease in aortic pressure

Question 8

Windkessel effect is not shown by which of the following vessel?

Accepted Answer

Radial

Answer

Renal

Answer

Aorta

Answer

Abdominal aorta

Question 9

If the contractility of the heart is decreased, which of the following is seen ?

Accepted Answer

Decreased stroke volume

Answer

Increased ejection fraction

Answer

Increased stroke work

Answer

Increased cardiac output

Question 10

What is the primary mechanism for maintaining constant cerebral blood flow despite changes in systemic blood pressure?

Accepted Answer

Myogenic autoregulation

Answer

Endothelial factors

Answer

Baroreceptor reflex

Answer

Metabolic control

Cardiovascular System — MCQs

Cardiovascular System — MCQs

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