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 (A)</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 (D)</p> Signup and view all the answers

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

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

What is the absolute refractory period of a cardiac myocyte?

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

Which feature is indicative of a right ventricular impulse block?

<p>Large R’ wave in V1/V2 (B)</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; (A)</p> Signup and view all the answers

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

<p>&quot;Repolarization&quot; (D)</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 (D)</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 (B)</p> Signup and view all the answers

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

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

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

<p>Period of ventricular ejection (C)</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 (B)</p> Signup and view all the answers

What is the normal ejection fraction (EF)?

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

What is a characteristic of eccentric hypertrophy?

<p>Dilated ventricle with thin wall (A)</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 (B)</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 (A)</p> Signup and view all the answers

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

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

What is the goal for preload in mitral stenosis?

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

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

<p>SA node (B)</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 (C)</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 (C)</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 (B)</p> Signup and view all the answers

What is contractility in relation to the heart muscle?

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

What happens during isovolumetric relaxation in the cardiac cycle?

<p>LV pressure falls below LA pressure (C)</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 (D)</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 (C)</p> Signup and view all the answers

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

<p>Potassium (A)</p> Signup and view all the answers

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

<p>RMP becomes more negative (C)</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 (B)</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 (B)</p> Signup and view all the answers

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

<p>-60 mV (A)</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 (A)</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 (C)</p> Signup and view all the answers

What is the formula for cardiac output (CO)?

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

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

<p>SV decreases (B)</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 (A)</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 (A)</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 (C)</p> Signup and view all the answers

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

<p>Surgical aortic valve replacement (B)</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 (A)</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) (A)</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 (A)</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 (A)</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 (A)</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 (D)</p> Signup and view all the answers

What is the primary surgical management option for aortic stenosis?

<p>Surgical aortic valve replacement (D)</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 (A)</p> Signup and view all the answers

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