Cardiac Physiology Quiz
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Questions and Answers

Intrinsic rate of SA node

60-100bpm

AV node intrinsic rate

40-60bpm

Purkinje fibers intrinsic rate

20-40bpm

___ molecules of sodium are pumped out for every ____ molecules of potassium pumped in

<p>3, 2</p> Signup and view all the answers

Speed of conduction for SA node

<p>0.5m/sec</p> Signup and view all the answers

AV node speed of conduction

<p>0.05m/sec</p> Signup and view all the answers

AV bundle speed of conduction

<p>2m/sec</p> Signup and view all the answers

Initial delay from SA to AV node: (in seconds)

<p>0.03sec</p> Signup and view all the answers

AV nodal + AV Bundle delay (in seconds)

<p>0.13sec</p> Signup and view all the answers

Total delay of conduction from atria to ventricles (in seconds)

<p>0.16sec</p> Signup and view all the answers

Total conduction time (including the terminal branches of Purkinje fibers)

<p>0.22sec</p> Signup and view all the answers

Speed of Conduction for Purkinje Fibers:

<p>4m/sec</p> Signup and view all the answers

Resting Membrane Potential of SA node:

<p>-50 to -60mV</p> Signup and view all the answers

Threshold potential of SA node

<p>-40mV</p> Signup and view all the answers

(Nodal cell) Funny Slow Na+ channels open at: (in mV)

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

(Nodal Cell) T-type Calcium channels open at (in mV):

<p>-55mV</p> Signup and view all the answers

(Nodal Cell) L-type Calcium channels open at (in mV)

<p>-40mV</p> Signup and view all the answers

Resting Membrane Potential of Cardiac Muscle (in mV)

<p>-85 to -90mV</p> Signup and view all the answers

Threshold potential of cardiac muscle (in mV)

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

Phase 0 - Fast Na+ channels open (in mV)

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

Phase 1: Fast Na+ channels close; Fast K+ channels open (use range +__ to +__ ), (single value)

<p>(+2 to +30), +20</p> Signup and view all the answers

In cardiac muscle action potential - Slow calcium channels open (in mV)

<p>-30 to -40mV</p> Signup and view all the answers

Lidocaine primarily affects which phases of the muscle fiber action potential?

<p>Phase 0 and Phase 4</p> Signup and view all the answers

Approximately how much blood in the ventricles at the end of diastole is ejected during systole?

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

The atria function as primer pumps that increase ventricular pumping effectiveness by as much as:(atrial kick)

<p>20%</p> Signup and view all the answers

The workout of the ventricle required to create kinetic energy of blood flow is about __ percent of the total work output of te ventricles.

<p>1%</p> Signup and view all the answers

The normal heart capacity to pump ____ to ____ % more blood than what the body needs at rest.

<p>300 - 400%</p> Signup and view all the answers

Cardioaccelerator fibers synapse at the ___ to ___ vertebral ganglia.

<p>1st to 5th</p> Signup and view all the answers

Cardioaccelerator fibers originate in the intermediolateral columns of higher thoracic segment (T__ to T__)

<p>T1 to T4</p> Signup and view all the answers

Severe stimulation of the vagus nerve can completely stop rhythmical excitation by the SA NODE -- ventricles stop beating for ___ to ___ seconds

<p>5 to 20 seconds</p> Signup and view all the answers

With vagal stimulation, the SA node becomes hyperpolarized with a resting membrane potential of -____ to -____mV

<p>-65 to -75mV</p> Signup and view all the answers

Max stimulation of vagus nerve stimulation decreases contractility by ____%

<p>30</p> Signup and view all the answers

Max SNS stimulation increases contractility by ____%

<p>100%</p> Signup and view all the answers

End systolic volume in mL

<p>50mL</p> Signup and view all the answers

End Diastolic Volume in mL

<p>120mL</p> Signup and view all the answers

Isolumetric contraction: (in seconds)

<p>0.02-0.03 seconds</p> Signup and view all the answers

Isovolumetric Relaxation (in seconds)

<p>0.03-0.06 seconds</p> Signup and view all the answers

Stretch of SA node can increase HR by ___%

<p>15</p> Signup and view all the answers

coronary blood flow: ___mL/100g cardiac tissue

<p>70mL</p> Signup and view all the answers

During strenuous excercise CO increases by ___ to ___ fold

<p>4 to 7</p> Signup and view all the answers

During strenuous excercise coronary blood flow increases by ___ to ___ fold to increase supply of nutrients

<p>3 to 4</p> Signup and view all the answers

Normal autoregulation ___ to ____mmHg

<p>60 to 140 mmHg</p> Signup and view all the answers

Baroreceptors within carotid sinus are not stimulated between ___ to ____ mmHg

<p>0 to 50mmHg</p> Signup and view all the answers

Baroreceptors within the carotid sinus have a maximum response at ____ mmHg

<p>180 mmHg</p> Signup and view all the answers

In mitral valve disease, lethal pulmonary edema does not occur until LAP rises above ___mmHg and sometimes as high as ___mmHg

<p>25mmHg to 40mmHg</p> Signup and view all the answers

The myocardium extracts ___ to ___% of oxygen from hemoglobin.

<p>65 to 70%</p> Signup and view all the answers

On the EKG run at typical speed, each vertical dark line represents (in seconds)

<p>0.20sec</p> Signup and view all the answers

Q-T interval (in seconds)

<p>0.35seconds</p> Signup and view all the answers

Interval between two consecutive QRS complexes (in seconds)

<p>0.83 seconds</p> Signup and view all the answers

P-R interval (in seconds):

<p>0.16 seconds</p> Signup and view all the answers

ventricular repolarization (in seconds)

<p>0.15 seconds</p> Signup and view all the answers

smaller thin vertical lines on EKG:

<p>0.04 seconds</p> Signup and view all the answers

atrial repolarization (in seconds)

<p>0.15-0.20 seconds</p> Signup and view all the answers

Normal voltage: T wave (in mV)

<p>0.2-0.3mV</p> Signup and view all the answers

Normal voltage: QRS complex

<p>1.0 to 1.5mV</p> Signup and view all the answers

Normal voltage: p wave in mV

<p>0.1 to 0.3mV</p> Signup and view all the answers

In the six standard chest leads of an ECG of a healthy adult heart, the QRS complexes are primarily positive in leads:

<p>V4, V5, V6</p> Signup and view all the answers

At what body temperature would a decreased heart rate likely occur due to the weakening of the heart muscle as a result of fever? ( degrees C)

<p>40.5</p> Signup and view all the answers

Angina typically manifests when the narrowing of the coronary artery reaches > ___%

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

Severe mitral stenosis is associated with a mitral valve orifice area narrowed to less than ___cm2

<p>1cm2</p> Signup and view all the answers

In cases of cardiac failure, sympathetic stimulation fortifies weakened musculature and enhances venous return by elevating tone across the majority of the circulatory system’s blood vessels. This response is typically developed within ____ seconds.

<p>30 seconds</p> Signup and view all the answers

Normal mitral valve size area ___ to ___ cm2

<p>4 to 6 cm2</p> Signup and view all the answers

Tricuspid Valve Normal area __ - __ cm2

<p>7 to 9cm2</p> Signup and view all the answers

Severe stenosis when area < __cm2, or when pressure gradient > __mmHg

<p>1cm2, &gt;5mmHg</p> Signup and view all the answers

Mitral valve Normal size: - cm2

<p>4 to 6cm2</p> Signup and view all the answers

MV stenosis occurs when area < __ cm2

<p>2cm2</p> Signup and view all the answers

Aortic Insufficiency patients asymptomatic - ___% mortality symptomatic - ___% mortality rate

<p>0.2%, 10%</p> Signup and view all the answers

Aortic valve Poor Prognosis If velocity > __mL/sec = poor prognosis Mean aortic valve gradient > __mmHg = poor prognosis

<p>4, 40</p> Signup and view all the answers

Triad of symptoms at < __cm2 Angina Syncope CHF

<p>1</p> Signup and view all the answers

Valve area < __cm2 = severe aortic stenosis, increased peri-operative mortality

<p>1</p> Signup and view all the answers

When valve area decreased by __% will have symptoms

<p>50%</p> Signup and view all the answers

90% of pts with RHD will have mitral involvement symptoms occur - years from RHD ->with reduction in valve area to <__cm2

<p>20 to 30, 2cm2</p> Signup and view all the answers

Aortic valve Normal size ___ - ___cm2

<p>2.5 to 3.5cm2</p> Signup and view all the answers

Aortic valve Minimal gradient __-__mmHg

<p>2,4</p> Signup and view all the answers

Aortic Valve Flow rate - ___ml/min

<p>250mL/min</p> Signup and view all the answers

Aortic Valve LV systolic pressure 100-300mmHg -> generates flow rate of ___-____mL

<p>250-300mL</p> Signup and view all the answers

Hypertension increases the risk of atherosclerotic coronary artery disease by at least two-fold, while combined with diabetes mellitus increases the risk by more than ______-fold.

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

Malignant hypertension is characterized by severe hypertension greater than / mmHg.

<p>210/120</p> Signup and view all the answers

95% of all cases of hypertension are classified as ______ hypertension.

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

Waiting at least ______ days is recommended after a myocardial infarction before undergoing elective surgery.

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

The risk of myocardial infarction after anesthesia is highest when surgery occurs less than ______ days after an MI.

<p>30</p> Signup and view all the answers

Stable angina usually occurs when there is more than ______% blockage of a coronary artery.

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

Acute postoperative hypertension is defined as a significant elevation in blood pressure with SBP ______ mmHg and above.

<p>180</p> Signup and view all the answers

Patients with stable angina and significant left main disease benefit from ______ before non-cardiac surgery.

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

The overall risk of myocardial infarction after general anesthesia is ______%.

<p>0.3</p> Signup and view all the answers

70-85% of children with hypertension have an underlying cause, with the most common being ______ disease.

<p>renal parenchymal</p> Signup and view all the answers

Cardiac muscle requires approximately ___ ml oxygen/100 g of muscle tissue/min just to remain alive.

<p>1.3</p> Signup and view all the answers

Flat or down sloping ST segment depression greater than ___ mV on the EKG is the most reliable sign of myocardial ischemia.

<p>0.1</p> Signup and view all the answers

Levels of cardiac troponins increase within ___ hours after myocardial injury.

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

Mitral regurgitation due to ischemic injury can occur ___ to ___ days after acute myocardial infarction.

<p>3, 7</p> Signup and view all the answers

Recommended time interval for elective angioplasty without stenting is ___ to ___ weeks.

<p>2, 4</p> Signup and view all the answers

The recommended time interval for elective drug-eluting stent placement is at least ___ months.

<p>6</p> Signup and view all the answers

Ejection fraction values are considered normal between ___% to ___%.

<p>50, 70</p> Signup and view all the answers

Reduced ejection fraction value is defined as below ___%.

<p>40</p> Signup and view all the answers

Pericarditis occurs as a common complication in ___% to ___% of patients after myocardial infarction.

<p>10, 15</p> Signup and view all the answers

The recommended time interval for elective bare-metal stent placement is at least ___ days.

<p>30</p> Signup and view all the answers

Study Notes

Hypertension and Cardiovascular Risk

  • Hypertension increases the risk of atherosclerotic coronary artery disease by at least two-fold.
  • When hypertension is combined with diabetes mellitus, the risk increases more than eight-fold.
  • A hypertensive crisis occurs when systolic blood pressure exceeds 180 mm Hg and/or diastolic exceeds 120 mm Hg.
  • Essential hypertension accounts for 95% of all hypertension cases.

Underlying Causes of Hypertension

  • In children aged birth to 12 years, 70-85% of hypertension cases have an underlying cause, commonly renal parenchymal disease or coarctation of the aorta.
  • In middle-aged adults (40-64 years), 8-12% of hypertension cases have an underlying cause.

Intraoperative Blood Pressure Management

  • Maintain intraoperative blood pressure within 10-20% of the patient's normal blood pressure outside the clinical setting.

Types of Hypertension

  • Malignant hypertension is defined as severe hypertension greater than 210/120 mmHg.
  • Acute postoperative hypertension refers to a significant elevation in blood pressure during the immediate postoperative period, with SBP 180 mmHg or higher or DBP 110 mmHg or above.

Myocardial Infarction (MI) Risk Associated with Anesthesia

  • Overall risk of MI following general anesthesia is 0.3%.
  • Risk of MI is elevated based on the timeline of a previous MI:
    • 6% if MI was 3-6 months prior.
    • 19% if MI was 1-2 months prior.
    • 33% if MI was within 30 days before surgery.
  • Mortality rate from reinfarction is approximately 50%.

Recommendations Post-MI

  • It is advised to wait at least 60 days after an MI before undergoing elective surgery.

Stable Angina and Surgical Risk

  • Stable angina typically manifests with greater than 70% blockage in a coronary artery.
  • General contraindications for surgery include an MI within 1 month, persistent ischemic risk, uncompensated heart failure, and severe aortic stenosis.
  • Patients with stable angina and significant coronary disease may require revascularization prior to non-cardiac surgery.

Timing for Elective Procedures Post-Stent Placement

  • Elective noncardiac surgery is discouraged within:
    • 4 to 6 weeks post bare metal stent placement.
    • 12 months post drug-eluting stent placement if antiplatelet therapy must be paused.

Cardiac Function and Myocardial Ischemia

  • Cardiac muscle requires approximately 1.3 ml of oxygen per 100 g of muscle tissue per minute to survive.
  • Flat or down sloping ST segment depression greater than 0.1 mV on EKG is a reliable indicator of myocardial ischemia.
  • Cardiac troponins (troponin T or I) increase within 3 hours post-myocardial injury and remain elevated for 7-10 days.
  • Angina at rest typically lasts longer than 10 minutes unless interrupted by antianginal medication.

Complications Following Myocardial Infarction

  • Pericarditis develops in 10-15% of patients a few days after MI.
  • Ischemic injury can lead to mitral regurgitation due to injury to papillary muscles 3-7 days post-AMI.
  • Elective angioplasty without stenting: 2-4 weeks.
  • Elective bare-metal stent placement: at least 30 days, preferably 12 weeks.
  • Elective coronary artery bypass grafting: at least 6 weeks, 12 weeks preferable.
  • Elective drug-eluting stent placement: at least 6 months, ideally 12 months following acute coronary syndrome.

Ejection Fraction (EF) Values

  • Normal ejection fraction ranges from 50% to 70%.
  • Reduced ejection fraction is defined as below 40%.

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Description

Test your knowledge on the intrinsic rates of the SA node, AV node, and Purkinje fibers. This quiz also covers the sodium and potassium pump dynamics and conduction speeds in cardiac physiology. Perfect for students of cardiac anatomy and physiology!

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