Cardiac Physiology 1.2
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Questions and Answers

What is the hallmark feature of right bundle branch block (RBBB) on an ECG?

  • Widened QRS complex and upwardly deflected in lead V1 (correct)
  • Deep S wave in V5/V6
  • Narrow QRS complex and downwardly deflected in lead V1
  • Large R’ wave in V5/V6

    • Which phase of the ventricular muscle action potential is characterized by the opening of voltage-gated L-type calcium channels?

  • Phase 0
  • Phase 3
  • Phase 1
  • Phase 2 (correct)

    • What is the resting membrane potential of the ventricular muscle?

  • -90 mV (correct)
  • -50 mV
  • -70 mV
  • -60 mV

    • During which phase of the action potential is there a restoration of membrane potential towards the resting state following depolarization?

    <p>Phase 3</p> Signup and view all the answers

    What is the threshold potential for the initiation of an action potential in excitable cells?

    <p>-70 mV</p> Signup and view all the answers

    Which phase of the cardiac action potential is characterized by a prolonged plateau phase?

    <p>Phase 2</p> Signup and view all the answers

    What is the absolute refractory period of a cardiac myocyte?

    <p>-90mV to -60mV</p> Signup and view all the answers

    Which feature is indicative of a right ventricular impulse block?

    <p>Large R’ wave in V1/V2</p> Signup and view all the answers

    "The difference in electrical potential between the inside and outside of the cell" refers to:

    <p>&quot;Resting membrane potential&quot;</p> Signup and view all the answers

    "The restoration of membrane potential towards RMP following depolarization" is known as:

    <p>&quot;Repolarization&quot;</p> Signup and view all the answers

    What do pressure-volume loops provide an assessment of?

    <p>Systolic and diastolic function as well as cardiac valve integrity</p> Signup and view all the answers

    During the period of isovolumic relaxation (diastole), what happens to the left ventricular (LV) volume?

    <p>It remains unchanged</p> Signup and view all the answers

    What is the formula to calculate stroke volume (SV) based on the pressure-volume loop?

    <p>$SV = EDV - ESV$</p> Signup and view all the answers

    Which period of the cardiac cycle represents ventricular ejection (systole)?

    <p>Period of ventricular ejection</p> Signup and view all the answers

    In a pressure-volume loop, where is diastolic blood pressure (DBP) measured?

    <p>Where the aortic valve opens</p> Signup and view all the answers

    What is the normal ejection fraction (EF)?

    <p>60-70%</p> Signup and view all the answers

    What is a characteristic of eccentric hypertrophy?

    <p>Dilated ventricle with thin wall</p> Signup and view all the answers

    What is the treatment for mitral stenosis?

    <p>$Na^+$ restriction, diuretics, $eta$ blockers, and surgical or percutaneous interventions</p> Signup and view all the answers

    What condition promotes transvalvular pressure gradient dependent on cardiac output, heart rate, and diastolic time?

    <p>Mitral stenosis</p> Signup and view all the answers

    What does critical mitral stenosis correspond to in terms of valve area?

    <p>0.5 cm2</p> Signup and view all the answers

    What is the goal for preload in mitral stenosis?

    <p>Maintain normal to increased preload (LVEDV)</p> Signup and view all the answers

    What is the primary role of the AV node in the heart's electrical conduction system?

    <p>To conduct the action potential from the SA node to the ventricles</p> Signup and view all the answers

    What is the function of the Purkinje fibers in the heart's electrical conduction system?

    <p>To rapidly conduct the action potential to myocytes throughout the ventricles</p> Signup and view all the answers

    Which structure allows for the spread of action potentials between myocardial cells in the heart?

    <p>Gap junctions</p> Signup and view all the answers

    During normal sinus rhythm (NSR), which pathway is preferentially responsible for electrical activation of the left atrium?

    <p>Bachmann’s bundle</p> Signup and view all the answers

    What is the purpose of the delay in propagation through the AV node?

    <p>To allow for simultaneous contraction of the atria and ventricles</p> Signup and view all the answers

    What is a hallmark sign of dysfunction in the left bundle branch?

    <p>Excess widths of QRS &gt; 0</p> Signup and view all the answers

    Which component of the heart's conduction system conducts electrical impulses from the AV node down the interventricular septum?

    <p>AV bundle (Bundle of His)</p> Signup and view all the answers

    What is responsible for triggering the initial depolarization in the heart's conduction system?

    <p>SA node</p> Signup and view all the answers

    What is the relationship between ventricular end-diastolic volume (EDV) and stroke volume (SV) according to the Frank-Starling Mechanism?

    <p>As EDV increases, SV increases</p> Signup and view all the answers

    What is the force that the ventricle must overcome to eject its stroke volume?

    <p>Intraventricular pressure during peak systole</p> Signup and view all the answers

    What effect does an increase in afterload have on the Frank-Starling curve?

    <p>Shifts the curve down and to the right</p> Signup and view all the answers

    What is contractility in relation to the heart muscle?

    <p>The intrinsic strength of the heart muscle</p> Signup and view all the answers

    During which phase of the cardiac cycle do the left and right ventricles contract and eject blood into the aorta and pulmonary artery?

    <p>Ejection</p> Signup and view all the answers

    What happens during isovolumetric relaxation in the cardiac cycle?

    <p>LV pressure falls below LA pressure</p> Signup and view all the answers

    What accounts for approximately 15-20% of ventricular filling during rapid filling in the cardiac cycle?

    <p>Atrial systole</p> Signup and view all the answers

    What does the Pressure-Volume Loop tell us about in the cardiac cycle?

    <p>Relationship between ventricular volume and ventricular pressure</p> Signup and view all the answers

    What is the primary determinant of resting membrane potential (RMP) in cells?

    <p>Potassium</p> Signup and view all the answers

    What happens to the RMP when serum potassium (K+) decreases?

    <p>RMP becomes more negative</p> Signup and view all the answers

    Which ion is responsible for depolarizing the cell when the resting membrane potential (RMP) approaches threshold potential?

    <p>Sodium</p> Signup and view all the answers

    What is the main purpose of the sodium-potassium ATPase (pump) in cells?

    <p>To remove Na+ ions from the cell</p> Signup and view all the answers

    What is the unique characteristic of the SA node's resting membrane potential (RMP)?

    <p>-60 mV</p> Signup and view all the answers

    What is the function of ectopic pacemakers in cardiac physiology?

    <p>Assume pacemaker responsibility in SA node disorder</p> Signup and view all the answers

    What is the effect of idiopathic fibrosis on the conduction system in cardiac physiology?

    <p>Impairs transmission of action potentials from atria to ventricles</p> Signup and view all the answers

    What is the formula for cardiac output (CO)?

    <p>$CO = HR imes SV$</p> Signup and view all the answers

    Which factor determines the preload or end-diastolic volume (EDV) in cardiac physiology?

    <p>Left atrial pressure at end of diastole</p> Signup and view all the answers

    What happens to stroke volume (SV) if systolic pressure is increased in cardiac physiology?

    <p>SV decreases</p> Signup and view all the answers

    What is the primary goal for anesthetic management in mitral stenosis?

    <p>Normal to increased preload, avoid tachycardia, and maintain contractility</p> Signup and view all the answers

    What is the main effect of aortic regurgitation on the left ventricle (LV)?

    <p>LV dilation and eccentric hypertrophy</p> Signup and view all the answers

    Which valve pathology is associated with a history of long asymptomatic period before the development of symptoms?

    <p>Aortic regurgitation</p> Signup and view all the answers

    What is the primary surgical management option for chronic aortic regurgitation?

    <p>Surgical aortic valve replacement</p> Signup and view all the answers

    What are the primary goals in aortic insufficiency/regurgitation management?

    <p>Normal to increased preload, decreased afterload, and low heart rate</p> Signup and view all the answers

    What is the main effect of mitral regurgitation on left ventricular compensation over time?

    <p>Dilating and increasing end-diastolic volume (EDV)</p> Signup and view all the answers

    Which valve pathology is associated with the triad of syncope, angina, and dyspnea in valve areas less than 1cm2?

    <p>Aortic stenosis</p> Signup and view all the answers

    What are the primary goals in mitral regurgitation/insufficiency management?

    <p>High preload, decreased afterload, and low heart rate</p> Signup and view all the answers

    What characterizes the wall of the left ventricle (LV) in aortic stenosis?

    <p>Thick LV wall with decreased compliance and narrowed chamber</p> Signup and view all the answers

    Which valve pathology is primarily associated with maintaining NSR, decreased afterload, and slight increase in heart rate for management?

    <p>Aortic Regurgitation/Insufficiency</p> Signup and view all the answers

    What is the primary surgical management option for aortic stenosis?

    <p>Surgical aortic valve replacement</p> Signup and view all the answers

    What is the main effect of mitral stenosis on cardiac output (CO)?

    <p>Up to 40% reduction in CO</p> Signup and view all the answers

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