Thrombolytic Agents — MCQs

10 questions

The clot formed after the coagulation cascade is not stable unless extensive cross-linking occurs. This is done by:

Bleeding crisis in acute idiopathic thrombo-cytopenic purpura is managed by all except -

A 60-year-old man with atrial fibrillation presents with sudden right arm and leg weakness, speech loss, and right facial droop that started 2 hours ago. CT scan shows no bleeding. What is the next step in management?

Which of these is not a risk factor for thromboembolism -

Partial thromboplastin time (PTT) correlates with which pathway or function?

The Renal function is best assessed by:

All are used to produce controlled hypotension except

What is the best treatment for anemia in patients with Chronic Renal Failure (CRF)?

Q10

A patient with a malignancy is undergoing chemotherapy. The platelet counts were reduced after the previous cycle of chemotherapy. Which of the following drugs can be used to treat this patient?

Thrombolytic Agents Indian Medical PG Practice Questions and MCQs

Question 1: The clot formed after the coagulation cascade is not stable unless extensive cross-linking occurs. This is done by:

A. Plasmin
B. Factor XIII (Correct Answer)
C. Thrombin
D. High molecular weight kininogen

Explanation: ***Factor XIII*** - **Factor XIIIa** (activated Factor XIII) is a **transglutaminase** that catalyzes the formation of **covalent bonds** between **fibrin monomers**, specifically between lysine and glutamine residues. - This cross-linking strengthens the **fibrin clot**, making it more resistant to mechanical stress and proteolytic degradation. *Plasmin* - **Plasmin** is an enzyme responsible for **fibrinolysis**, meaning it breaks down fibrin clots. - It acts to remodel and **dissolve clots**, not to stabilize them. *Thrombin* - **Thrombin** (Factor IIa) is a key enzyme in the coagulation cascade that converts **fibrinogen into fibrin monomers**. - While essential for clot formation, thrombin's primary role is to create the fibrin mesh, not to extensively cross-link it for stability. *High molecular weight kininogen* - **High molecular weight kininogen (HMWK)** is a cofactor in the **intrinsic coagulation pathway**, facilitating the activation of Factor XII and prekallikrein. - It is involved in initiating coagulation but does not directly participate in the cross-linking and stabilization of the fibrin clot.

Question 2: Bleeding crisis in acute idiopathic thrombo-cytopenic purpura is managed by all except -

A. Intravenous immunoglobulin
B. Prednisolone
C. Eltrombopag (Correct Answer)
D. RhIG

Explanation: ***Eltrombopag*** - **Eltrombopag** is a **thrombopoietin receptor agonist** used for chronic idiopathic thrombocytopenic purpura (ITP) to increase platelet production. - It is **not** used for the immediate management of an acute bleeding crisis, as its effects on platelet counts take several days to manifest. *Intravenous immunoglobulin* - **Intravenous immunoglobulin (IVIG)** works by blocking **Fc receptors** on macrophages, thereby reducing the destruction of antibody-coated platelets. - It is a **first-line treatment** for acute ITP, especially in cases with severe bleeding or very low platelet counts, providing a rapid increase in platelet count. *Prednisolone* - **Prednisolone**, a corticosteroid, is a **first-line treatment** for acute ITP, as it suppresses the immune system and reduces antibody production and platelet destruction. - It helps to quickly raise platelet counts and is effective in managing bleeding episodes, though its effects are not as immediate as IVIG. *RhIG* - **Rh immune globulin (RhIG)** is used in **Rh-positive** patients with ITP to cause a transient hemolytic anemia, which occupies splenic macrophages and reduces platelet destruction. - It `is an effective option` for acute ITP, particularly in patients who require a rapid increase in platelet count and are Rh-positive.

Question 3: A 60-year-old man with atrial fibrillation presents with sudden right arm and leg weakness, speech loss, and right facial droop that started 2 hours ago. CT scan shows no bleeding. What is the next step in management?

A. Intravenous thrombolysis (Correct Answer)
B. Surgical thrombectomy
C. Heparin
D. Aspirin

Explanation: No change to the explanation was requested other than the addition of citations. ***Intravenous thrombolysis*** - The patient presents with **acute ischemic stroke symptoms** [1] within the 4.5-hour window from symptom onset , and the CT scan shows no hemorrhage , making him a candidate for **tPA**. - **Atrial fibrillation** puts the patient at high risk for cardioembolic stroke , which can be effectively treated with tPA if given early . *Surgical thrombectomy* - This is an intervention for **large vessel occlusion** but is typically considered for patients who are outside the IV tPA window (usually 4.5 hours) or have contraindications, and it often has a longer therapeutic window (up to 24 hours in select cases). - While it may be considered for this patient, **IV thrombolysis** is the immediate next step given he is within the 4.5-hour window and has no contraindications. *Heparin* - **Anticoagulation with unfractionated heparin** is not recommended for acute ischemic stroke without clear indications due to the increased risk of hemorrhagic transformation. - While the patient has atrial fibrillation, starting anticoagulation acutely is usually deferred for at least 24 hours after tPA administration or in cases of larger infarcts due to the risk of bleeding. *Aspirin* - **Aspirin** is an antiplatelet agent used for **secondary stroke prevention** and in some cases for acute ischemic stroke, but it is less effective than tPA for acute reperfusion . - While it may be given later, it is not the primary immediate treatment for acute ischemic stroke eligible for thrombolysis.

Question 4: Which of these is not a risk factor for thromboembolism -

A. Regular exercise (Correct Answer)
B. Superficial thrombophlebitis
C. Myocardial infarction
D. Estrogen therapy

Explanation: ***Regular exercise*** - **Regular exercise** is a protective factor against thromboembolism, as it improves blood circulation and reduces venous stasis. - It also helps maintain a healthy weight and cardiovascular fitness, lowering overall risk. *Superficial thrombophlebitis* - While typically less serious than deep vein thrombosis (DVT), **superficial thrombophlebitis** can extend into deeper veins or serve as a risk marker for DVT. - Inflammation and clot formation in superficial veins can sometimes trigger or coexist with more significant thromboembolic events [1]. *Myocardial infarction* - A **myocardial infarction** increases the risk for thromboembolism due to cardiac wall motion abnormalities and subsequent eddy currents causing thrombus formation within the ventricle [2]. - The damaged heart muscle can also release pro-coagulant factors, further elevating the risk. *Estrogen therapy* - **Estrogen therapy**, particularly in higher doses or certain formulations, is known to increase the risk for venous and arterial thromboembolism. - This is due to stimulating the production of clotting factors and reducing the activity of natural anticoagulants.

Question 5: Match the following drugs in Column A with their contraindications in Column B. | Column A | Column B | | :-- | :-- | | 1. Morphine | 1. QT prolongation | | 2. Amiodarone | 2. Thromboembolism | | 3. Vigabatrin | 3. Pregnancy | | 4. Estrogen preparations | 4. Head injury |

A. A-1, B-3, C-2, D-4
B. A-4, B-1, C-3, D-2 (Correct Answer)
C. A-3, B-2, C-4, D-1
D. A-2, B-4, C-1, D-3

Explanation: ***A-4, B-1, C-3, D-2*** - **Morphine** is contraindicated in **head injury** as it can increase intracranial pressure and mask neurological symptoms. - **Amiodarone** is contraindicated in patients with **QT prolongation** due to its risk of inducing more severe arrhythmias like Torsades de Pointes. - **Vigabatrin** is contraindicated during **pregnancy** due to its potential for teratogenicity and adverse effects on fetal development. - **Estrogen preparations** are contraindicated in patients with a history of **thromboembolism** due to their increased risk of blood clot formation. *A-1, B-3, C-2, D-4* - This option incorrectly matches **Morphine** with QT prolongation and **Estrogen preparations** with head injury, which are not their primary contraindications. - It also incorrectly links **Vigabatrin** with thromboembolism and **Amiodarone** with pregnancy. *A-3, B-2, C-4, D-1* - This choice incorrectly associates **Morphine** with pregnancy and **Vigabatrin** with head injury, which are not the most critical or direct contraindications. - It also misaligns **Amiodarone** with thromboembolism and **Estrogen preparations** with QT prolongation. *A-2, B-4, C-1, D-3* - This option incorrectly matches **Morphine** with thromboembolism and **Amiodarone** with head injury, which are not their most significant contraindications. - It also incorrectly links **Vigabatrin** with QT prolongation and **Estrogen preparations** with pregnancy.

Question 6: Partial thromboplastin time (PTT) correlates with which pathway or function?

A. Intrinsic pathway (Correct Answer)
B. Extrinsic pathway
C. Fibrinogen function
D. Platelet function

Explanation: ***Function of platelets*** - The **partial thromboplastin time (PTT)** primarily assesses the **intrinsic and common pathways** of blood coagulation [1], indirectly reflecting platelet function through clotting factors. - Abnormal PTT can indicate issues with **platelet activation** and interactions in the clotting process, although it is not a direct measure of platelet count or function. *Intrinsic and common pathway* - While PTT is indeed related to the **intrinsic pathway** [1], it does not correlate directly with the **overall intrinsic pathway function** alone, as it primarily assesses clotting factor activity. - The **PTT** specifically examines factors like **factor VIII** and **IX** [1], rather than the broader aspect of the intrinsic mechanism itself. *Fibrinogen level* - Fibrinogen levels are assessed using the **prothrombin time (PT)** and not through PTT, as fibrinogen is involved in the **common pathway** but does not directly correlate with PTT. - Fibrinogen deficiency can affect clotting time, but the **PTT** primarily evaluates other factors independent of fibrinogen concentration. *Extrinsic and common pathway* - The **extrinsic pathway** is evaluated using **prothrombin time (PT)** [1], not PTT, which focuses on intrinsic factors' performance. - PTT measures factors involved mainly in the **intrinsic pathway**, including **factor XII**, **XI**, **IX**, and **VIII** [1], making this option incorrect. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Hemodynamic Disorders, Thromboembolic Disease, and Shock, pp. 128-130.

Question 7: The Renal function is best assessed by:

A. Tc 99m DMSA
B. Tc 99m DTPA
C. Tc 99m pertechnetate
D. Tc 99m MAG3 (Correct Answer)

Explanation: ***Tc 99m MAG3*** - **Technetium-99m mercaptoacetyltriglycine (MAG3)** is the **preferred agent for dynamic renal scintigraphy** and assessment of **overall renal function**. - It is a **renal tubular agent** with a high extraction fraction (40-50%) that assesses **effective renal plasma flow (ERPF)** and **tubular secretion**. - **Superior to DTPA** for functional assessment due to better image quality, faster clearance, and excellent performance even in **impaired renal function**. - Provides comprehensive evaluation of **renal perfusion, function, and excretion** in a single study. *Tc 99m DMSA* - **Technetium-99m dimercaptosuccinic acid (DMSA)** is a **cortical imaging agent** used primarily for **static renal imaging**. - Excellent for assessing **renal anatomy**, detecting **cortical scarring**, **pyelonephritis**, and **differential renal function**. - It binds to the cells of the **proximal tubules** and is retained (40-50% at 6 hours), making it unsuitable for dynamic functional studies or excretion assessment. *Tc 99m DTPA* - **Technetium-99m diethylenetriaminepentaacetic acid (DTPA)** is a **glomerular filtration agent** used to measure **GFR**. - Excreted solely by **glomerular filtration** (no tubular secretion), making it the gold standard for **GFR measurement**. - However, it has a **lower extraction fraction (20%)** compared to MAG3, resulting in poorer image quality and less reliable assessment in patients with **impaired renal function**. - MAG3 has largely replaced DTPA as the preferred agent for routine dynamic renal studies. *Tc 99m pertechnetate* - **Technetium-99m pertechnetate** is primarily used for **thyroid imaging** and detecting **Meckel's diverticulum** (taken up by mucous-secreting cells). - **Not used for renal function assessment** as it does not provide reliable information about glomerular or tubular function.

Question 8: All are used to produce controlled hypotension except

A. Nitroglycerine
B. Isoflurane
C. Propofol (Correct Answer)
D. Esmolol

Explanation: ***Propofol*** - While propofol can cause hypotension, it is primarily used as an **intravenous anesthetic** for induction and maintenance and for sedation. - Its hypotensive effect is a common side effect due to **vasodilation** and decreased cardiac output, but it is not typically optimized or used as a primary agent for controlled hypotension in a surgical setting. *Nitroglycerine* - **Nitroglycerine** is a potent vasodilator, primarily acting on veins, and is commonly used to induce **controlled hypotension** during surgery by reducing preload and afterload. - Its rapid onset and short duration of action make it suitable for titrating blood pressure. *Isoflurane* - **Isoflurane** is an inhaled anesthetic that causes dose-dependent myocardial depression and vasodilation, leading to a decrease in blood pressure. - It is frequently used to provide **controlled hypotension** during surgical procedures. *Esmolol* - **Esmolol** is a rapid-acting, ultra-short-acting beta-blocker that can reduce blood pressure by decreasing heart rate and myocardial contractility. - It is often used to manage **hypertension** and to induce controlled hypotension, especially when a rapid and reversible effect is desired.

Question 9: What is the best treatment for anemia in patients with Chronic Renal Failure (CRF)?

A. Oral Iron Therapy
B. Erythropoietin Stimulating Agents (Correct Answer)
C. Blood transfusion
D. Androgenic Steroids

Explanation: ***Erythropoietin Stimulating Agents*** - **Erythropoietin Stimulating Agents (ESAs)** are the cornerstone of anemia treatment in CRF because the primary cause of anemia in these patients is inadequate production of **endogenous erythropoietin** by the damaged kidneys [1]. - ESAs stimulate the bone marrow to produce red blood cells, effectively reversing the anemia and improving symptoms like fatigue and exercise intolerance [1]. *Oral Iron Therapy* - While **iron deficiency** often coexists with **anemia of chronic disease** in CRF patients, oral iron alone is usually insufficient to correct the anemia; it only addresses the iron component. - Many CRF patients have **functional iron deficiency** due to chronic inflammation, which impairs iron utilization, making oral iron less effective even with adequate stores. *Blood transfusion* - **Blood transfusions** provide a rapid increase in hemoglobin but are not the preferred long-term treatment for anemia in CRF due to risks of **iron overload**, **alloreactions**, and potential sensitization, which can complicate future transplantation. - Transfusions are typically reserved for acute, severe anemia or specific circumstances where ESAs are ineffective or contraindicated. *Androgenic Steroids* - **Androgenic steroids** can stimulate erythropoiesis, but their use is limited due to significant side effects such as **hepatotoxicity**, **virilization**, and **cardiac complications**, making them a less favorable option compared to ESAs. - They are considered a secondary or tertiary option, often in patients unresponsive to primary treatments or when other options are exhausted.

Question 10: A patient with a malignancy is undergoing chemotherapy. The platelet counts were reduced after the previous cycle of chemotherapy. Which of the following drugs can be used to treat this patient?

A. Oprelvekin (IL-11) - stimulates platelet production (Correct Answer)
B. Filgrastim - stimulates white blood cell production
C. Amifostine - protects against chemotherapy toxicity
D. Erythropoietin - stimulates red blood cell production

Explanation: ***Oprelvekin (IL-11) - stimulates platelet production*** - **Oprelvekin** is a recombinant interleukin-11 (IL-11) that directly stimulates the proliferation and maturation of **megakaryocytes**, leading to increased platelet production. - It is specifically indicated for the prevention of **severe thrombocytopenia** and the reduction of the need for platelet transfusions following myelosuppressive chemotherapy. *Filgrastim - stimulates white blood cell production* - **Filgrastim** is a **granulocyte colony-stimulating factor (G-CSF)** that primarily acts on neutrophil precursors, promoting their proliferation and maturation. - It is used to prevent and treat **neutropenia** and reduce the incidence of febrile neutropenia, but it does not significantly affect platelet counts. *Amifostine - protects against chemotherapy toxicity* - **Amifostine** is a **cytoprotective agent** that reduces toxicities associated with chemotherapy and radiation by preferentially protecting non-malignant cells. - It does not directly stimulate blood cell production but rather acts as a **free radical scavenger** to mitigate damage from cytotoxic treatments. *Erythropoietin - stimulates red blood cell production* - **Erythropoietin** is a **hematopoietic growth factor** that specifically stimulates the production of **red blood cells** by promoting the proliferation and differentiation of erythroid progenitor cells. - It is used to treat **anemia**, particularly in patients with chronic kidney disease or those undergoing chemotherapy, but it has no role in managing thrombocytopenia.

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