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  • Question 1 - What percentage of cardiac output is delivered to the skin? ...

    Correct

    • What percentage of cardiac output is delivered to the skin?

      Your Answer: 2%

      Explanation:

      Making up 4-5% of total body weight, the skin receives approximately 2% of cardiac output.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      5.2
      Seconds
  • Question 2 - Calculate the cardiac output of a patient with the following measurements: oxygen uptake...

    Incorrect

    • Calculate the cardiac output of a patient with the following measurements: oxygen uptake 200 ml/min, oxygen concentration in the peripheral vein 7 vol%, oxygen concentration in the pulmonary artery 10 vol% and oxygen concentration in the aorta 15 vol%.

      Your Answer: 2000 ml/min

      Correct Answer: 4000 ml/min

      Explanation:

      The Fick’s principle states that the uptake of a substance by an organ equals the arteriovenous difference of the substance multiplied by the blood flowing through the organ. We can thus calculate the pulmonary blood flow with pulmonary arterial (i.e., mixed venous) oxygen content, aortic oxygen content and oxygen uptake. The pulmonary blood flow, systemic blood flow and cardiac output can be considered the same assuming there are no intracardiac shunts. Thus, we can calculate the cardiac output. Cardiac output = oxygen uptake/(aortic − mixed venous oxygen content) = 200 ml/min/(15 ml O2/100 ml − 10 ml O2/100 ml) = 200 ml/min/(5 ml O2/100 ml) = 200 ml/min/0.05 = 4000 ml/min.

      It is crucial to remember to use pulmonary arterial oxygen content and not peripheral vein oxygen content, when calculating the cardiac output by Fick’s method.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      10.4
      Seconds
  • Question 3 - A 40 year old man suffered severe trauma following a MVA. His BP...

    Correct

    • A 40 year old man suffered severe trauma following a MVA. His BP is 72/30 mmhg, heart rate of 142 beats/mins and very feeble pulse. He was transfused 3 units of blood and his BP returned to 100/70 and his heart rate slowed to 90 beats/min. What decreased after transfusion?

      Your Answer: Total peripheral resistance

      Explanation:

      The patient is in hypovolemic shock, he is transfused with blood, this fluid resuscitation will result in a decreased sympathetic discharge and adequate ventricular filling which will result in the decreases TPR with an increased CO and cardiac filling pressures

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      18
      Seconds
  • Question 4 - A 29-year-old pregnant woman develops severe hypoxaemia with petechial rash and confusion following...

    Correct

    • A 29-year-old pregnant woman develops severe hypoxaemia with petechial rash and confusion following a fracture to her left femur. Which is the most probable cause of these symptoms in this patient?

      Your Answer: Fat embolism

      Explanation:

      Fat embolism is a life-threatening form of embolism in which the embolus consists of fatty material or bone marrow particles that are introduced into the systemic venous system. It may be caused by long-bone fractures, orthopaedic procedures, sickle cell crisis, parenteral lipid infusion, burns and acute pancreatitis. Patients with fat embolism usually present with symptoms that include skin, brain, and lung dysfunction.

    • This question is part of the following fields:

      • Cardiovascular
      • Pathology
      9.2
      Seconds
  • Question 5 - A 40 year old man suffered severe trauma following an MVA. His BP...

    Correct

    • A 40 year old man suffered severe trauma following an MVA. His BP is 70/33 mmhg, heart rate of 140 beats/mins and very feeble pulse. He was transfused 3 units of blood resulting in his BP returning to 100/70 and his heart rate to 90 beats/min. What decreased following transfusion?

      Your Answer: Total peripheral resistance

      Explanation:

      The patient is in hypovolemic shock, he is transfused with blood to replace the volume lost. It is important not only to replace fluids but stop active bleeding in resuscitation. Fluid replacement will result in a decreased sympathetic discharge and adequate ventricular filling thus reducing total peripheral resistance and increasing cardiac output and cardiac filling pressures.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      120.9
      Seconds
  • Question 6 - A victim of road traffic accident presented to the emergency department with a...

    Correct

    • A victim of road traffic accident presented to the emergency department with a blood pressure of 120/90 mm Hg, with a drop in systolic pressure to 100 mm Hg on inhalation. This is known as:

      Your Answer: Pulsus paradoxus

      Explanation:

      Weakening of pulse with inhalation and strengthening with exhalation is known as pulsus paradoxus. This represents an exaggeration of the normal variation of the pulse in relation to respiration. It indicates conditions such as cardiac tamponade and lung disease. The paradox refers to the auscultation of extra cardiac beats on inspiration, as compared to the pulse. Due to a decrease in blood pressure, the radial pulse becomes impalpable along with an increase in jugular venous pressure height (Kussmaul sign). Normal systolic blood pressure variation (with respiration) is considered to be >10 mmHg. It is >100 mmHg in Pulsus paradoxus. It is also predictive of the severity of cardiac tamponade.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      14.8
      Seconds
  • Question 7 - A 30 year old female presented in the emergency with an irregular pulse....

    Correct

    • A 30 year old female presented in the emergency with an irregular pulse. Her ECG showed absent P-waves with irregular RR interval. What is the most likely diagnosis?

      Your Answer: Atrial fibrillation

      Explanation:

      Atrial fibrillation is one of the most common cardiac arrhythmias. It is often asymptomatic but may present with symptoms of palpitations, fainting, chest pain and heart failure. Characteristic findings are: absence of P-waves, unorganised electrical activity in their place, irregularity of RR interval due to irregular conduction of impulses to the ventricles and if paroxysmal AF is suspected, episodes may be documented with the use of Holter monitoring

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      25.6
      Seconds
  • Question 8 - An ECG of a 30 year old woman revealed low voltage QRS complexes....

    Correct

    • An ECG of a 30 year old woman revealed low voltage QRS complexes. This patient is most probably suffering from?

      Your Answer: Pericardial effusion

      Explanation:

      The QRS complex is associated with current that results in the contraction of both the ventricles. As ventricles have more muscle mass than the atria, they result in a greater deflection on the ECG. The normal duration of a QRS complex is 10s. A wide and deep Q wave depicts myocardial infarction. Abnormalities in the QRS complex maybe indicative of a bundle block, ventricular tachycardia or hypertrophy of the ventricles. Low voltage QRS complexes are characteristic of pericarditis or a pericardial effusion.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      8.7
      Seconds
  • Question 9 - Calculate the cardiac stroke volume of a patient whose oxygen consumption (measured by...

    Correct

    • Calculate the cardiac stroke volume of a patient whose oxygen consumption (measured by analysis of mixed expired gas) is 300 ml/min, arterial O2 content is 20 ml/100 ml blood, pulmonary arterial O2 content is 15 ml/100 ml blood and heart rate is 60/min.

      Your Answer: 100 ml

      Explanation:

      By Fick’s principle, VO2 = Q × (CA (O2) − CV (O2)) where VO2 = O2 consumption, Q = cardiac output and CA(O2) and CV(O2) are arterial and mixed venous O2 content respectively. Thus, in the given problem, 300 ml O2/min = Q × (20−15) ml O2/100 ml. Thus, Q = 6000 ml blood/min. Then, we can calculate stroke volume by dividing the cardiac output with heart rate. Thus, stroke volume = 6000 ml/min divided by 60/min stroke volume = 100 ml.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      3.1
      Seconds
  • Question 10 - Calculate the cardiac output in an adult male with the following parameters:

    Heart...

    Correct

    • Calculate the cardiac output in an adult male with the following parameters:

      Heart rate 70 beats/min

      Arterial [O2] 0.24 ml O2/min

      Venous [O2] 0.16 ml O2/mi

      Whole body O2 consumption 500 ml/min

      Pulmonary diastolic pressure 15 mmHg

      Pulmonary systolic pressure 25 mmHg

      Wedge pressure 5 mmHg.

      Your Answer: 6.25 l/min

      Explanation:

      As per Fick’s principle, VO2 = (CO × CAO2) – (CO × CVO2) where VO2 = oxygen consumption, CO = cardiac output, CAO2 = oxygen concentration of arterial blood and CVO2 = oxygen concentration of venous blood. Thus, CO = VO2/CAO2– CVO2, CO = 500/0.24 – 0.16, CO = 500/0.8, CO = 6.25 l/min.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      11.9
      Seconds
  • Question 11 - During strenuous exercise, what else occurs besides tachycardia? ...

    Correct

    • During strenuous exercise, what else occurs besides tachycardia?

      Your Answer: Increased stroke volume

      Explanation:

      During strenuous exercise there is an increase in:

      – Heart rate, stroke volume and therefore cardiac output. (CO = HR x SV)

      – Respiratory rate (hyperventilation) which will lead to a reduction in Paco2.

      – Oxygen demand of skeletal muscle, therefore leading to a reduction in mixed venous blood oxygen concentration.

      Renal blood flow is autoregulated, so renal blood flow is preserved and will tend to remain the same. Mean arterial blood pressure is a function of cardiac output and total peripheral resistance and will increase with exercise, mainly as a result of the increase in cardiac output that occurs.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      38.2
      Seconds
  • Question 12 - When at rest, which of the following will be higher in a marathon...

    Correct

    • When at rest, which of the following will be higher in a marathon runner compared to an untrained individual?

      Your Answer: Cardiac stroke volume

      Explanation:

      Cardiac muscle hypertrophy is seen in trained athletes as compared to the normal population. This hypertrophy results in higher stroke volume at rest and increased cardiac reserve (maximum cardiac output during exercise). However, the cardiac output at rest is almost the same in both trained and untrained people. This is because in trained athletes, the heart rate is slower, even up to 40-50 beats/min. There is minimal affect of athletic training on oxygen consumption and respiratory rate.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      6.8
      Seconds
  • Question 13 - A 55-year-old woman died 3 years after a cardiac transplant due to worsening...

    Correct

    • A 55-year-old woman died 3 years after a cardiac transplant due to worsening congestive heart failure. Autopsy revealed diffuse hyperplasia of the vascular intima involving the entire length of the coronary arteries. The most probable cause of deterioration of the cardiac function is:

      Your Answer: Coronary atherosclerosis

      Explanation:

      Allograft coronary artery disease (CAD) can begin right after the transplant and is the major cause of later death in cardiac transplant recipients. This form of atherosclerosis progresses quickly resulting in allograft failure. Due to lack of premonitory symptoms CAD may lead to sudden death.

    • This question is part of the following fields:

      • Cardiovascular
      • Pathology
      32
      Seconds
  • Question 14 - Which of the following compensatory parameters is responsible for causing an increase in...

    Correct

    • Which of the following compensatory parameters is responsible for causing an increase in the blood pressure in a 30 year old patient with a BP of 40 mmHg?

      Your Answer: Baroreceptor reflex

      Explanation:

      The baroreflex or baroreceptor reflex is one of the body’s homeostatic mechanisms for regulating blood pressure. It provides a negative feedback response in which an elevated blood pressure will causes blood pressure to decrease; similarly, decreased blood pressure depresses the baroreflex, causing blood pressure to rise. The system relies on specialised neurones (baroreceptors) in the aortic arch, carotid sinuses and elsewhere to monitor changes in blood pressure and relay them to the brainstem. Subsequent changes in blood pressure are mediated by the autonomic nervous system. Baroreceptors include those in the auricles of the heart and vena cava, but the most sensitive baroreceptors are in the carotid sinuses and aortic arch. The carotid sinus baroreceptors are innervated by the glossopharyngeal nerve (CN IX); the aortic arch baroreceptors are innervated by the vagus nerve (CN X).

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      21.2
      Seconds
  • Question 15 - Increased resistance to flow of blood in cerebral vessels is most likely seen...

    Correct

    • Increased resistance to flow of blood in cerebral vessels is most likely seen in:

      Your Answer: Elevation in systemic arterial pressure from 100 to 130 mmHg

      Explanation:

      Constant cerebral blood flow is maintained by autoregulation in the brain, which causes an increase in local vascular resistance to offset an increase in blood pressure. There will be an increase in cerebral blood flow (and decrease in resistance to cerebral blood flow) with a decrease in arterial oxygen or an increase in arterial CO2. Similarly, a decrease in viscosity will also increase the blood flow. Due to increased brain metabolism and activity during a seizure, there will also be an increase in the cerebral blood flow.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      22.1
      Seconds
  • Question 16 - A 32-year-old man presents to the doctor complaining of pain in his left...

    Correct

    • A 32-year-old man presents to the doctor complaining of pain in his left calf whilst walking. He says that the pain goes away after a short period of rest but starts again during exercise or walking. The man reveals he has been a smoker for the last 15 years. His blood pressure, blood sugar and cholesterol level are normal. Artery biopsy shows intraluminal thrombosis and vasculitis. What's is the most likely cause of these findings?

      Your Answer: Buerger's disease

      Explanation:

      Thromboangiitis obliterans, also known as Buerger’s disease, is a rare type of occlusive peripheral arterial disease, usually seen in smokers, most commonly in men aged 20 to 40. Symptoms most often include intermittent claudication, skin changes, painful ulcers on extremities, pain in the extremities during rest and gangrene. Diagnosis is based on clinical findings, arteriography, echocardiography, and computed tomography angiography. A difference in blood pressure between arms, or between the arms and legs is a common finding. Electrocardiographic findings include nonspecific abnormality or normal results.

    • This question is part of the following fields:

      • Cardiovascular
      • Pathology
      25.4
      Seconds
  • Question 17 - A 30 year old man suffered severe blood loss, approx. 20-30% of his...

    Incorrect

    • A 30 year old man suffered severe blood loss, approx. 20-30% of his blood volume. What changes are most likely seen in the pulmonary vascular resistance (PVR) and pulmonary artery pressure (PAP) respectively following this decrease in cardiac output?

      Your Answer: Decrease Increase

      Correct Answer: Increase Decrease

      Explanation:

      Hypovolemia will result in the activation of the sympathetic adrenal discharge resulting is a decrease pulmonary artery pressure and an elevated pulmonary vascular resistance.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      31.3
      Seconds
  • Question 18 - Calculate the stroke volume in a patient admitted for coronary bypass surgery, with...

    Correct

    • Calculate the stroke volume in a patient admitted for coronary bypass surgery, with the following parameters pre-operatively:

      Oxygen consumption = 300 ml/min

      Arterial oxygen content = 20 ml/100 ml blood

      Pulmonary arterial oxygen content = 15 ml/100 ml blood and Heart rate = 100 beats/min.

      Your Answer: 60 ml

      Explanation:

      By Fick’s principle, cardiac output can be calculated as follows: VO2 = CO × (CAO2– CVO2) where VO2= oxygen consumption, CO = cardiac output, CAO2 = arterial oxygen content and CvO2 = mixed venous oxygen content. Thus, in the given problem, 300 ml/min = CO × (20 – 15) ml/100 ml CO = 300 × 100/5 ml/min CO = 6000 ml/min. Also, cardiac output = stroke volume × heart rate. Thus, 6000 ml/min = stroke volume × 100 beats/min. Hence, stroke volume = 6000/100 ml/min which is 60 ml/min.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      13.8
      Seconds
  • Question 19 - A new-born was found to have an undeveloped spiral septum in the heart....

    Correct

    • A new-born was found to have an undeveloped spiral septum in the heart. This is characteristic of which of the following?

      Your Answer: Persistent truncus arteriosus

      Explanation:

      Persistent truncus arteriosus is a congenital heart disease that occurs when the primitive truncus does not divide into the pulmonary artery and aorta, resulting in a single arterial trunk. The spiral septum is created by fusion of a truncal septum and the aorticopulmonary spiral septum. Incomplete development of these septa results in incomplete separation of the common tube of the truncus arteriosus and the aorticopulmonary trunk.

    • This question is part of the following fields:

      • Cardiovascular
      • Pathology
      17.2
      Seconds
  • Question 20 - For calculation of cardiac output by Fick's principle, which of the following vessels...

    Correct

    • For calculation of cardiac output by Fick's principle, which of the following vessels is the best source of venous blood to determine the arterial-to-venous oxygen tension difference?

      Your Answer: Pulmonary artery

      Explanation:

      Fick’s principle states that the total uptake (or release) of a substance by peripheral tissues is equal to the product of the blood flow to the peripheral tissues and the arterial– venous concentration difference (gradient) of the substance. It is used to measure the cardiac output, and the formula is Cardiac output = oxygen consumption divided by arteriovenous oxygen difference. Assuming there are no shunts across the pulmonary system, the pulmonary blood flow equals the systemic blood flow. The arterial and venous blood oxygen content is measured by sampling from the pulmonary artery (low oxygen content) and pulmonary vein (high oxygen content). Peripheral arterial blood is used as a surrogate for the pulmonary vein.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      4.6
      Seconds
  • Question 21 - A 75-year old patient is in atrial fibrallation but has never been on...

    Correct

    • A 75-year old patient is in atrial fibrallation but has never been on anticoagulation therapy. To reduce the risk of future emboli, she would benefit from starting on long-term warfarin. Arterial emboli leading to acute limb ischaemia most commonly lodge at which one of the following sites?

      Your Answer: Common femoral artery

      Explanation:

      The common femoral artery is the commonest site of arterial emboli causing acute limb ischemia. The treatment of choice is urgent femoral embolectomy.

    • This question is part of the following fields:

      • Cardiovascular
      • Pathology
      28.1
      Seconds
  • Question 22 - Calculate the total peripheral resistance for a patient with a blood pressure of...

    Correct

    • Calculate the total peripheral resistance for a patient with a blood pressure of 130/70 mm HG and cardiac output of 5 litres / min?

      Your Answer: 18 mmHg × min/l

      Explanation:

      Total peripheral resistance = Mean arterial pressure/Cardiac output. And the mean arterial pressure = Diastolic pressure + 1/3 (Systolic pressure – Diastolic pressure), i.e., 70 + 1/3 (130-70) = 90 mmHg. Therefore, total peripheral resistance = 90 mmHg/5 l per min = 18 mmHg × min/l.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      6.5
      Seconds
  • Question 23 - Under normal conditions, what is the major source of energy of cardiac muscles?...

    Correct

    • Under normal conditions, what is the major source of energy of cardiac muscles?

      Your Answer: Fatty acids

      Explanation:

      Under basal conditions, most of the energy needed by cardiac muscle for metabolism is derived from fats (60%), 35% by carbohydrates, and 5% by ketones and amino acids. However, after intake of large amounts of glucose, lactate and pyruvate are mainly used. During prolonged starvation, fat acts as the primary source. 50% of the used lipids are sourced from circulating fatty acids.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      6.6
      Seconds
  • Question 24 - Purkinje fibres in the heart conduct action potentials at the rate of: ...

    Correct

    • Purkinje fibres in the heart conduct action potentials at the rate of:

      Your Answer: 1.5–4.0 m/s

      Explanation:

      Purkinje fibres control the heart rate along with the sinoatrial node (SA node) and the atrioventricular node (AV node). The QRS complex is associated with the impulse passing through the Purkinje fibres. These fibres conduct action potential about six times faster than the velocity in normal cardiac muscle.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      12.4
      Seconds
  • Question 25 - What is the normal duration of the ST segment? ...

    Correct

    • What is the normal duration of the ST segment?

      Your Answer: 0.08 s

      Explanation:

      The ST segment lies between the QRS complex and the T-wave. The normal duration of the ST segment is 0.08 s. ST-segment elevation or depression may indicate myocardial ischaemia or infarction.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      5.3
      Seconds
  • Question 26 - A 59-year-old man was brought to the emergency department by his family after...

    Correct

    • A 59-year-old man was brought to the emergency department by his family after complaining of sudden, severe upper back pain and a ripping sensation, that radiated to his neck. On arrival, his pulse was weak in one arm compared with the other however his ECG result was normal. Which of the following is most probably the cause of these findings and symptoms?

      Your Answer: Acute aortic dissection

      Explanation:

      Acute aortic dissection is a serious condition in which the inner layer of the aorta tears and the blood flows in between the inner and middle layers of the aorta causing their separation (dissection). Aortic dissection can lead to rupture or decreased blood flow to organs. Clinical manifestations most often include the sudden onset of severe, tearing or ripping chest pain that can radiate to the shoulder, back or neck; syncope; altered mental status; dyspnoea; pale skin; stroke symptoms etc. The diagnosis of acute aortic dissection is based on clinical findings, imaging studies, electrocardiography and laboratory analysis.

    • This question is part of the following fields:

      • Cardiovascular
      • Pathology
      48.4
      Seconds
  • Question 27 - The most likely cause of prominent U waves on the electrocardiogram (ECG) of...

    Correct

    • The most likely cause of prominent U waves on the electrocardiogram (ECG) of a patient is:

      Your Answer: Hypokalaemia

      Explanation:

      The U-wave, not always visible in ECGs, is thought to represent repolarisation of papillary muscles or Purkinje fibres. When seen, it is very small and occurs after the T-wave. Inverted U-waves indicate myocardial ischaemia or left ventricular volume overload. Prominent U-waves are most commonly seen in hypokalaemia. Other causes include hypercalcaemia, thyrotoxicosis, digitalis exposure, adrenaline and class 1A and 3 anti-arrhythmic agents. It can also be seen in congenital long-QT syndrome and in intracranial haemorrhage.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      9.2
      Seconds
  • Question 28 - In a cardiac cycle, what event does the closing of atrioventricular (AV) valves...

    Incorrect

    • In a cardiac cycle, what event does the closing of atrioventricular (AV) valves coincide with?

      Your Answer: Beginning of diastole

      Correct Answer: Second heart sound

      Explanation:

      The beginning of ventricular systole corresponds to the beginning of the QRS complex in the ECG. The beginning of the ventricular systole also corresponds to the closure of the atrioventricular valves, causing the first heart sound (S1). S2, the second heart sound is due to closure of the aortic and pulmonary valves at the end of ventricular systole.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      7.8
      Seconds
  • Question 29 - Which of the following is the cause of flattened (notched) T waves on...

    Correct

    • Which of the following is the cause of flattened (notched) T waves on electrocardiogram (ECG)?

      Your Answer: Hypokalaemia

      Explanation:

      The T-wave is formed due to ventricular repolarisation. Normally, it is seen as a positive wave. It can be normally inverted (negative) in V1 (occasionally in V2-3 in African-Americans/Afro-Caribbeans). Hyperacute T-waves are the earliest ECG change of acute myocardial infarction. ECG findings of hyperkalaemia include high, tent-shaped T-waves, a small P-wave and a wide QRS complex. Hypokalaemia results in flattened (notched) T-waves, U-waves, ST-segment depression and prolonged QT interval.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      7.7
      Seconds
  • Question 30 - What percentage of the cardiac output is delivered to the brain? ...

    Correct

    • What percentage of the cardiac output is delivered to the brain?

      Your Answer: 15%

      Explanation:

      Among all body organs, the brain is most susceptible to ischaemia. Comprising of only 2.5% of total body weight, the brain receives 15% of the cardiac output. Oxygen extraction is also higher with venous oxygen levels approximating 13 vol%, and arteriovenous oxygen difference of 7 vol%.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      5.6
      Seconds
  • Question 31 - What is the normal duration of PR interval on an electrocardiogram of a...

    Correct

    • What is the normal duration of PR interval on an electrocardiogram of a healthy individual?

      Your Answer: 0.12–0.20 s

      Explanation:

      PR interval extends from the beginning of the P-wave until the beginning of the QRS complex. The normal duration of the PR interval is 0.12-0.20 s. It can be prolonged in first degree heart block, and reduced in Wolff-Parkinson-White syndrome.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      21.5
      Seconds
  • Question 32 - Calculate the pulmonary vascular resistance in an adult male with the following parameters:...

    Correct

    • Calculate the pulmonary vascular resistance in an adult male with the following parameters:

      Heart rate 70 beats/min

      Arterial [O2] 0.24 ml O2/min

      Venous [O2] 0.16 ml O2/mi

      Whole body O2 consumption 500 ml/min

      Pulmonary diastolic pressure 15 mmHg

      Pulmonary systolic pressure 25 mmHg

      Wedge pressure 5 mmHg.

      Your Answer: 2.0 resistance units (mmHg/l per min)

      Explanation:

      Pulmonary vascular resistance (PVR) = (Mean pulmonary artery pressure – Pulmonary capillary wedge pressure) divided by Cardiac output. To get cardiac output, Fick’s principle needs to be applied which states that VO2 = (CO × CAO2) – (CO × CVO2) where VO2 = oxygen consumption, CO = cardiac output, CA = oxygen concentration of arterial blood and CVO2 = oxygen concentration of venous blood. Thus, CO = VO2/CAO2– CVO2, CO = 500/0.24–0.16, CO = 500/0.8, CO = 6.25 l/min. To calculate mean pulmonary artery pressure, we use the formula: Mean pulmonary artery pressure = Diastolic pressure + 1/3(Systolic pressure – Diastolic pressure). Thus, Mean pulmonary artery pressure = 15 + 1/3(25 – 15) = 15 + 3. 33 = 18.33. Substituting these values in the first formula, PVR = 18.3–5/6.25 = 13.5/5.25 = 2.0 resistance units (mmHg/l per min) approximately.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      4.8
      Seconds
  • Question 33 - Which organ is most vulnerable to haemorrhagic shock? ...

    Correct

    • Which organ is most vulnerable to haemorrhagic shock?

      Your Answer: Kidneys

      Explanation:

      At rest, the brain receives 15% cardiac output, muscles 15%, gastrointestinal tract 30% and kidneys receive 20%. However, if normalised by weight, the largest specific blood flow is received by the kidneys at rest (400 ml/min x 100g), making them highly vulnerable in the case of a haemorrhagic shock.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      3.5
      Seconds
  • Question 34 - Which of the following is responsible for the maximum increase in total peripheral...

    Correct

    • Which of the following is responsible for the maximum increase in total peripheral resistance on sympathetic stimulation?

      Your Answer: Arterioles

      Explanation:

      Arterioles are also known as the resistance vessels as they are responsible for approximately half the resistance of the entire systemic circulation. They are richly innervated by the autonomic nervous system and hence, will bring about the maximum increase in peripheral resistance on sympathetic stimulation.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      7.9
      Seconds
  • Question 35 - During cardiac catheterisation in a 20-year old man, the following data is obtained:...

    Correct

    • During cardiac catheterisation in a 20-year old man, the following data is obtained: Pressure (mmHg), O2 saturation (%) Right atrium 7 (N = 5) 90 (N = 75), Right ventricle 35/7 (N = 25/5) 90 (N = 75), Pulmonary artery 35/8 (N = 25/15), 90 (N = 75), Left atrium 7 (N = 9) 95 (N = 95), Left ventricle 110/7 (N = 110/9) 95 (N = 95), Aorta 110/75 (N = 110/75) 95 (N = 95) where N = Normal value. What is the likely diagnosis?

      Your Answer: Atrial septal defect

      Explanation:

      A congenital heart disease, ASD or atrial septal defect leads to a communication between the right and left atria due to a defect in the interatrial septum. This leads to mixing of arterial and venous blood from the right and left side of the heart. The hemodynamic significance of this defect depends on the presence of shunting of blood. Normally, the left side of the heart has higher pressure than the right as the left side has to pump blood throughout the body. A large ASD (> 9 mm) will result in a clinically significant left-to-right shunt, causing volume overload of the right atrium and ventricle, eventually leading to heart failure. Cardiac catheterization would reveal very high oxygen saturation in the right atrium, right ventricle and pulmonary artery. Eventually, the left-to-right shunt will lead to pulmonary hypertension and increased afterload in the right ventricle, along with the increased preload due to the shunted blood. This will either cause right ventricular failure, or raise the pressure in the right side of the heart to equal or more than that in the left. Elevation of right atrial pressure to that of left atrial pressure would thus lead to diminishing or complete cessation of the shunt. If left uncorrected, there will be reversal of the shunt, known as Eisenmenger syndrome, resulting in clinical signs of cyanosis as the oxygen-poor blood form right side of the heart will mix with the blood in left side and reach the peripheral vascular system.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      3.7
      Seconds
  • Question 36 - In a cardiac cycle, what event does the opening of the atrioventricular (AV)...

    Incorrect

    • In a cardiac cycle, what event does the opening of the atrioventricular (AV) valves coincide with?

      Your Answer: End of diastole

      Correct Answer: Beginning of diastole

      Explanation:

      Cardiac diastole refers to the time period when the heart is relaxed after contraction and is preparing to refill with blood. Both ventricular and atrial diastole are together known as complete cardiac diastole. At its beginning, the ventricles relax, causing a drop in the ventricular pressure. As soon as the left ventricular pressure drops below that in left atrium, the mitral valve opens and there is ventricular filling of blood. Similarly, the tricuspid valve opens filling the right atrium.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      8.8
      Seconds
  • Question 37 - A 13 year old girl presented with signs of shortness of breath, chest...

    Correct

    • A 13 year old girl presented with signs of shortness of breath, chest pain, non-productive cough, oedema of the lower extremities and cyanosis of the fingertips. She has a history of a ventricular septal defect not surgically corrected. The most probable cause of these symptoms is:

      Your Answer: Shunt reversal

      Explanation:

      A ventricular septal defect (VSD) is a common form of congenital heart defects and is characterised by the presence of a hole in the wall that separates the right from the left ventricle. Medium or large defects can cause many complications. One of these complication is Eisenmenger syndrome, characterised by reversal of the shunt (from left-to-right shunt into a right-to-left) ,cyanosis and pulmonary hypertension.

    • This question is part of the following fields:

      • Cardiovascular
      • Pathology
      17.1
      Seconds
  • Question 38 - Calculate the resistance of the artery if the pressure at one end is...

    Correct

    • Calculate the resistance of the artery if the pressure at one end is 60 mmHg, pressure at the other end is 20 mm Hg and the flow rate in the artery is 200 ml/min.

      Your Answer: 0.2

      Explanation:

      Flow in any vessel = Effective perfusion pressure divided by resistance, where effective perfusion pressure is the mean intraluminal pressure at the arterial end minus the mean pressure at the venous end. Thus, in the given problem, resistance = (60 − 20)/200 = 0.2 mmHg/ml per min.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      12.2
      Seconds
  • Question 39 - A 63-year-old woman complains of a new, persisting headache. She is diagnosed with...

    Correct

    • A 63-year-old woman complains of a new, persisting headache. She is diagnosed with vasculitis and the histopathological sample revealed giant-cell arteritis. What is the most probable diagnose?

      Your Answer: Temporal arteritis

      Explanation:

      Giant cell arteritis (GCA), also known as temporal arteritis, is the most common systemic inflammatory vasculitis that occurs in adults. It is of unknown aetiology and affects arteries large to small however the involvement of the superficial temporal arteries is almost always present. Other commonly affected arteries include the ophthalmic, occipital and vertebral arteries, therefore GCA can result in systemic, neurologic, and ophthalmologic complications. GCA usually is found in patients older than 50 years of age and should always be considered in the differential diagnosis of a new-onset headache accompanied by an elevated erythrocyte sedimentation rate. Diagnosis depends on the results of artery biopsy.

    • This question is part of the following fields:

      • Cardiovascular
      • Pathology
      12
      Seconds
  • Question 40 - Decreased velocity of impulse conduction through the atrioventricular node (AV node) in the...

    Correct

    • Decreased velocity of impulse conduction through the atrioventricular node (AV node) in the heart will lead to:

      Your Answer: Increased PR interval

      Explanation:

      AV node damage may lead to an increase in the PR interval to as high as 0.25 – 0.40 s (normal = 0.12 – 0.20 s). In the case of severe impairment, there might be a complete failure of passage of impulses leading to complete block. In this case, the atria and ventricles will beat independently of each other.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      13.7
      Seconds
  • Question 41 - A 15-day old male baby was brought to the emergency department with sweating...

    Correct

    • A 15-day old male baby was brought to the emergency department with sweating and his lips turning blue while feeding. He was born full term. On examination, his temperature was 37.9°C, blood pressure 75/45 mmHg, pulse was 175/min, and respiratory rate was 42/min. A harsh systolic ejection murmur could be heard at the left upper sternal border. X-ray chest showed small, boot-shaped heart with decreased pulmonary vascular markings. He most likely has:

      Your Answer: Tetralogy of Fallot

      Explanation:

      The most common congenital cyanotic heart disease and the most common cause of blue baby syndrome, Tetralogy of Fallot shows four cardiac malformations occurring together. These are ventricular septal defect (VSD), pulmonary stenosis (right ventricular outflow obstruction), overriding aorta (degree of which is variable), and right ventricular hypertrophy. The primary determinant of severity of disease is the degree of pulmonary stenosis. Tetralogy of Fallot is seen in 3-6 per 10,000 births and is responsible for 5-7% congenital heart defects, with slightly higher incidence in males. It has also been associated with chromosome 22 deletions and DiGeorge syndrome. It gives rise to right-to-left shunt leading to poor oxygenation of blood. Primary symptom is low oxygen saturation in the blood with or without cyanosis at birth of within first year of life. Affected children ay develop acute severe cyanosis or ‘tet spells’ (sudden, marked increase in cyanosis, with syncope, and may result in hypoxic brain injury and death). Other symptoms include heart murmur, failure to gain weight, poor development, clubbing, dyspnoea on exertion and polycythaemia. Chest X-ray reveals characteristic coeur-en-sabot (boot-shaped) appearance of the heart. Treatment consists of immediate care for cyanotic spells and Blalock–Taussig shunt (BT shunt) followed by corrective surgery.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      47.2
      Seconds
  • Question 42 - If the blood flow is constant, oxygen extraction by tissues will show the...

    Correct

    • If the blood flow is constant, oxygen extraction by tissues will show the greatest decrease due to which of the following interventions?

      Your Answer: Tissue cooling

      Explanation:

      With a constant blood flow to a given tissue bed, there will be an increase in oxygen extraction by the tissue with the following; an increase in tissue metabolism and oxygen requirements: warming (or fever), exercise, catecholamines and thyroxine. With cooling, the demand for oxygen decreases, leading to decreased oxygen extraction.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      17.3
      Seconds
  • Question 43 - A 45-year-old man presents to the emergency department with an irregular pulse and...

    Correct

    • A 45-year-old man presents to the emergency department with an irregular pulse and shortness of breath. Electrocardiography findings show no P waves, normal QRS complexes and an irregularly irregular rhythm. The patient most probably has:

      Your Answer: Atrial fibrillation

      Explanation:

      Atrial fibrillation is one of the most common arrhythmias, characterised by an irregular and rapid heart rate. Due to the decreased cardiac output, atrial fibrillation increases the risk of heart failure. It can also lead to thrombus formation which may lead to thromboembolic events. Clinical findings include palpitations, shortness of breath, fatigue, chest pain and confusion. The diagnosis is made by electrocardiographic findings which include absent P wave, fibrillatory (f) waves between QRS complexes and irregularly irregular R-R intervals.

    • This question is part of the following fields:

      • Cardiovascular
      • Pathology
      18.7
      Seconds
  • Question 44 - Ventricular filling follows a delay caused by? ...

    Correct

    • Ventricular filling follows a delay caused by?

      Your Answer: AV node

      Explanation:

      The AV node is a conducting tissue found between the atria and the ventricles of the heart. It conducts electrical signal from the atria to the ventricles and acts a delaying mechanism preventing the atria and the ventricles from contracting at the same time. This decremental conduction prevents premature ventricular contraction in cases such as atrial fibrillation. A delay in the AV node is the reason for the PR segment seen on the ECG. In certain types of supraventricular tachycardia, a person could have two AV nodes; this will cause a loop in electrical current and uncontrollably rapid heart beat. When this electricity catches up with itself, it will dissipate and return to a normal heart rate.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      6.7
      Seconds
  • Question 45 - During cardiac catheterisation, if the blood sample from the catheter shows an oxygen...

    Correct

    • During cardiac catheterisation, if the blood sample from the catheter shows an oxygen saturation of 70%, and the pressure ranging from 12 to 24 mm Hg, it implies that the catheter tip is located in the:

      Your Answer: Pulmonary artery

      Explanation:

      Normal values for various parameters are as follows:

      Systolic arterial blood pressure (SBP): 90–140 mmHg.

      Diastolic arterial blood pressure: 60–90 mmHg.

      Mean arterial blood pressure (MAP): SBP + (2 × DBP)/3 (normal range: 70-105 mmHg).

      Right atrial pressure (RAP): 2–6 mmHg.

      Systolic right ventricular pressure (RVSP): 15–25 mmHg.

      Diastolic right ventricular pressure (RVDP): 0–8 mmHg.

      Pulmonary artery pressure (PAP): Systolic (PASP) is 15-25 mmHg and Diastolic (PADP) is 8–15 mmHg.

      Pulmonary artery wedge pressure (PAWP): 6–12 mmHg.

      Left atrial pressure (LAP): 6–12 mmHg.

      Thus, the given value indicates that the position of catheter tip is likely to be in the pulmonary artery.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      9.5
      Seconds
  • Question 46 - As per the Poiseuille-Hagen formula, doubling the diameter of a vessel will change...

    Correct

    • As per the Poiseuille-Hagen formula, doubling the diameter of a vessel will change the resistance of the vessel from 16 peripheral resistance units (PRU) to:

      Your Answer: 1 PRU

      Explanation:

      Poiseuille-Hagen formula for flow in along narrow tube states that F = (PA– PB) × (Π/8) × (1/η) × (r4/l) where F = flow, PA– PB = pressure difference between the two ends of the tube, η = viscosity, r = radius of tube and L = length of tube. Also, flow is given by pressure difference divided by resistance. Hence, R = 8ηL ÷ Πr4. Hence, the resistance of the vessel changes in inverse proportion to the fourth power of the diameter. So, if the diameter of the vessel is increased to twice the original, it will lead to decrease in resistance to one-sixteenth its initial value.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      5.3
      Seconds
  • Question 47 - A 27-year-old woman, who had been taking a combined oral contraceptive for 6...

    Correct

    • A 27-year-old woman, who had been taking a combined oral contraceptive for 6 months, presented with inguinal pain and oedema of the left leg. Which of the following investigations would you recommend to help confirm the diagnosis?

      Your Answer: Duplex scan

      Explanation:

      Oral combined contraceptive pill (OCCP) is a drug used for birth control and treating a number of other conditions. Women who take the OCP have a higher risk of developing deep vein thrombosis (DVT), usually in the legs. Duplex ultrasonography is a safe and non-invasive technique which is used for diagnosing the presence of lower extremity thrombi.

    • This question is part of the following fields:

      • Cardiovascular
      • Pathology
      8.8
      Seconds
  • Question 48 - If a 70-year-old man with known atrial fibrillation dies suddenly, which of these...

    Incorrect

    • If a 70-year-old man with known atrial fibrillation dies suddenly, which of these is the most likely cause of death?

      Your Answer: Venous thrombosis

      Correct Answer: Thromboembolism

      Explanation:

      In atrial fibrillation, the abnormal atrial contraction can cause blood to stagnate in the left atrium and form a thrombus, which may then embolize. The patient’s history of AF suggest an embolic disease, which lead to his death.

    • This question is part of the following fields:

      • Cardiovascular
      • Pathology
      11.1
      Seconds
  • Question 49 - Calculate the stroke volume in an adult male with the following parameters:

    Heart...

    Correct

    • Calculate the stroke volume in an adult male with the following parameters:

      Heart rate 70 beats/min

      Arterial [O2] 0.24 ml O2/min

      Venous [O2] 0.16 ml O2/mi

      Whole body O2 consumption 500 ml/min

      Pulmonary diastolic pressure 15 mmHg

      Pulmonary systolic pressure 25 mmHg

      Wedge pressure 5 mmHg.

      Your Answer: 90 ml

      Explanation:

      Fick’s principle states that, VO2 = (CO × CAO2) – (CO × CVO2) where VO2 = oxygen consumption, CO = cardiac output, CAO2 = oxygen concentration of arterial blood and CVO2 = oxygen concentration of venous blood. Thus, CO = VO2/CAO2– CVO2, CO = 500/0.24–0.16, CO = 500/0.8, CO = 6.25 l/min. Cardiac output is also given by product of stroke volume and heart rate. Thus, stroke volume = cardiac output / heart rate = 6.25/70 × 1000 stroke volume = 90 ml approximately.

    • This question is part of the following fields:

      • Cardiovascular
      • Physiology
      5.2
      Seconds
  • Question 50 - A 34-year-old woman with severe burns, presented to casualty with a blood pressure...

    Correct

    • A 34-year-old woman with severe burns, presented to casualty with a blood pressure of 75/40 mmHg and pulse of 172/minute. Obviously the patient is in shock. Which type of shock is it more likely to be?

      Your Answer: Hypovolaemic shock

      Explanation:

      Shock is a life-threatening condition that occurs when the organs and tissues of the body are not receiving a sufficient flow of blood. Lack of blood flow, oxygen and nutrients results in the inability to function properly and damage to many organs. Shock requires immediate treatment because, if left untreated the impaired tissue perfusion and cellular hypoxia can cause irreversible tissue injury, collapse, coma or even death. There are various types of physiological shock, including: cardiogenic (due to heart damage), hypovolaemic (due to low total volume of blood or plasma), neurogenic (due to nervous system damage), septic (due to infections) and anaphylactic shock (due to allergic reactions). Hypovolaemic shock can be caused by blood loss due to trauma, internal bleeding or other fluid loss due to severe burns, prolonged diarrhoea, vomiting and sweating.

    • This question is part of the following fields:

      • Cardiovascular
      • Pathology
      16.3
      Seconds

SESSION STATS - PERFORMANCE PER SPECIALTY

Cardiovascular (45/50) 90%
Physiology (34/38) 89%
Pathology (11/12) 92%
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