Cardiac Responses to Mechanical Stimulation in Sports
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Questions and Answers

What condition is primarily associated with mechanosensitive cardiac responses during sports activities?

  • Heart murmurs
  • Sudden cardiac death (correct)
  • Cardiac arrest
  • Atrial fibrillation

Which aspect of the cardiac system is implicated in the mechano-electric feedback mechanism?

  • Electrical dynamics (correct)
  • Hormonal balance
  • Blood pressure regulation
  • Neural conduction

What was observed during the pre-cordial impact in the study with an anesthetized pig?

  • Reduction in vascular resistance
  • Decrease in heart rate
  • Increase in stroke volume
  • Cardiac rhythm disturbances (correct)

Which cardiac event was NOT measured in the schematic representation of effects from pre-cordial mechanical stimulation?

<p>Pulmonary embolism (C)</p> Signup and view all the answers

What type of impact site locations were considered in the observations regarding sudden cardiac death?

<p>Various sports activities (A)</p> Signup and view all the answers

Which rhythm disturbance is characterized by the absence of electrical impulses in the heart?

<p>Complete heart block (C)</p> Signup and view all the answers

Which intervention timing was found to be critical in influencing cardiac rhythm disturbances?

<p>During the T-wave upstroke (A)</p> Signup and view all the answers

What is the primary focus of mechano-electric coupling in the heart?

<p>Contractile dynamics (B)</p> Signup and view all the answers

What effect does hypertrophy have on stretch-activated currents in ventricular myocytes?

<p>It increases their amplitude. (B)</p> Signup and view all the answers

What is the primary alteration in the cycle length of rabbit SAN pacemaker cells under stretch conditions?

<p>Decrease by 14.2 ms. (B)</p> Signup and view all the answers

Which parameter showed an increase after applying stretch to rabbit SAN pacemaker cells?

<p>Spontaneous depolarization rate. (D)</p> Signup and view all the answers

How does stretch impact the maximum upstroke velocity in rabbit SAN pacemaker cells?

<p>Decreases it moderately. (C)</p> Signup and view all the answers

What is the recovery percentage of maximum diastolic potential after stretch is removed in rabbit SAN pacemaker cells?

<p>99.6% (B)</p> Signup and view all the answers

What happens to the early repolarization velocity when stretch is applied to SAN pacemaker cells?

<p>It increases. (C)</p> Signup and view all the answers

What was the maximum diastolic potential value during control conditions in rabbit SAN cells?

<p>54.3 mV (B)</p> Signup and view all the answers

What is one of the two mechanisms responsible for mechanotransduction in living cells?

<p>Stretch-activated channel activation. (D)</p> Signup and view all the answers

What effect does acute obstruction of the right ventricular outflow tract have on cardiac action potentials?

<p>It induces early afterdepolarizations. (B)</p> Signup and view all the answers

Which of the following describes the relationship between radial artery pressure and action potential length?

<p>Higher pressure correlates with lengthened action potential. (B)</p> Signup and view all the answers

What effect does increased venous return have on heart rate and blood pressure?

<p>It increases heart rate and blood pressure. (B)</p> Signup and view all the answers

What are the electrophysiological effects of systolic stretch on normal cardiac function?

<p>It enhances cardiac contractility and conduction. (D)</p> Signup and view all the answers

Which statement is true regarding the mechanical activation of cation-selective channels?

<p>It can induce arrhythmias during early repolarization. (B)</p> Signup and view all the answers

What does the summary of diastolic stretch effects entail?

<p>It modulates electrophysiological properties. (B)</p> Signup and view all the answers

What was the focus of the study by Kohl et al. in Cardiovasc Res 2001?

<p>The relationship between blood pressure and cardiac action potentials. (B)</p> Signup and view all the answers

How does incremental left ventricular volume affect the heart?

<p>It mimics conditions of heart block. (D)</p> Signup and view all the answers

What is the spontaneous depolarization time defined as?

<p>Time from MDP to threshold (C)</p> Signup and view all the answers

Which phase of repolarization is associated with a late repolarization velocity?

<p>Secondary slow phase of repolarization (B)</p> Signup and view all the answers

In the context of action potentials, what does the threshold to peak time refer to?

<p>Time from threshold to maximum systolic potential (A)</p> Signup and view all the answers

How does mechanical stress affect action potential profiles?

<p>It induces membrane depolarization and prolongs action potential. (A)</p> Signup and view all the answers

What is likely to occur during mechanical stimulation of a ventricular myocyte?

<p>Increased whole cell current response to stretch. (C)</p> Signup and view all the answers

Which of the following best describes the relationship between filling pressure and hemodynamics?

<p>Filling pressure can affect hemodynamics in complex ways. (D)</p> Signup and view all the answers

What effect does preload have on Ventricular Electric Remodeling (VER)?

<p>Preload influences the electrical properties of the myocardium. (B)</p> Signup and view all the answers

What is the significance of the sinoatrial node (SAN) in the context of action potential dynamics?

<p>It is responsible for the coordination of heartbeats. (C)</p> Signup and view all the answers

Which type of rats are represented by the abbreviation SHR in the study?

<p>Spontaneously Hypertensive Rats (D)</p> Signup and view all the answers

What measurement was taken from the ventricular myocytes at -45 mV?

<p>Amplitude of ISAC (A)</p> Signup and view all the answers

What does EET stand for in the context of chemical–mechanical synergism?

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

Which of the following is true regarding the age of the animal models used in the study?

<p>WKY rats come in both 3-month and 15-month age groups (B)</p> Signup and view all the answers

What does MSCC stand for in relation to mechanotransduction?

<p>Mechanosensitive Cation Channel (A)</p> Signup and view all the answers

Which of the following was NOT specified as a type of myocyte involved in the study?

<p>Zebra fish myocytes (A)</p> Signup and view all the answers

The study primarily focused on which phenomenon related to myocytes?

<p>Mechanosensitivity of ion channels (B)</p> Signup and view all the answers

Which signaling pathway is associated with the chemical–mechanical synergism mentioned?

<p>PLC and PLA2 pathways (A)</p> Signup and view all the answers

What impact does sarcomere length have on cardiac myocytes?

<p>It affects the electric stability of cardiac myocytes. (B)</p> Signup and view all the answers

What event does a preload increase in a myocyte primarily lead to?

<p>Stretching of the myocyte. (A)</p> Signup and view all the answers

Which of the following best describes mechanochemical sensing in cardiac myocytes?

<p>A mechanism that enables myocytes to translate mechanical stimuli into biochemical signals. (D)</p> Signup and view all the answers

What does the CRU Ca2+ release current in cardiac myocytes help to determine?

<p>Determine stable versus unstable electric states. (A)</p> Signup and view all the answers

Which factor primarily influences the calcium transient (CaT) peak in myocytes?

<p>Inhibition of nitric oxide synthase (NOS). (C)</p> Signup and view all the answers

In which context is an increase in spark number significant?

<p>Enhancing calcium release in cardiomyocytes. (A)</p> Signup and view all the answers

Which of the following techniques is used to analyze cellular responses under mechanical load?

<p>3-D elastic matrix imaging. (C)</p> Signup and view all the answers

What role does the z-line distance have in cardiac myocyte stability?

<p>It influences the stability of the electrical environment. (B)</p> Signup and view all the answers

What is the primary outcome of perfusion in the context of cardiac myocytes?

<p>Enhanced oxygen delivery and nutrient supply. (D)</p> Signup and view all the answers

What is the significance of using crosslinkers like 4-boronate-PEG in cardiac research?

<p>To facilitate the immobilization of cells for study. (D)</p> Signup and view all the answers

Which of the following statements about electric field excitation is true?

<p>It is a method to stimulate myocyte contraction and activity. (C)</p> Signup and view all the answers

How does mechanical load typically affect cardiac myocyte contraction?

<p>It enhances contraction efficiency. (B)</p> Signup and view all the answers

Why is nitric oxide important in the context of cardiac myocytes?

<p>It plays a role in regulating calcium homeostasis. (C)</p> Signup and view all the answers

What does the term 'spark number' refer to regarding cardiac myocytes?

<p>The count of calcium release events occurring in a specified area. (D)</p> Signup and view all the answers

Which segment shows a statistically significant decrease in action potential duration during ventricular electric remodeling (VER)?

<p>Anterior segment in Endocardial cells (D)</p> Signup and view all the answers

What is the overall trend of action potential duration (APD) changes in epicardial cells during VER compared to controls?

<p>APD significantly increases (A)</p> Signup and view all the answers

Which type of ventricular cells experienced the greatest increase in action potential duration during VER in the posterior segment?

<p>Epicardial cells (C)</p> Signup and view all the answers

In which type of cell did the action potential duration show the least change during ventricular electric remodeling (VER) in the anterior segment?

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

What is the distinguishing feature of the action potential duration changes in lateral segment midmyocardial cells during VER?

<p>A significant decrease (C)</p> Signup and view all the answers

What is the impact of stretch on the maximum upstroke velocity in spontaneously beating rabbit sinoatrial node cells?

<p>It decreases and shows partial recovery after stretch is removed. (C)</p> Signup and view all the answers

Which parameter exhibited the least recovery percentage after the removal of stretch in rabbit sinoatrial nodal cells?

<p>Cycle length (C)</p> Signup and view all the answers

Which of the following electrophysiological parameters increased under stretch conditions in rabbit sinoatrial node pacemaker cells?

<p>Spontaneous depolarization rate (D)</p> Signup and view all the answers

What happens to the threshold to peak time in rabbit SAN cells when stretch is applied?

<p>It increases slightly. (C)</p> Signup and view all the answers

In the context of the provided data, which parameter experienced the greatest percentage change due to mechanical stretch?

<p>Early repolarization velocity (B)</p> Signup and view all the answers

How does stretch affect the maximum diastolic potential in rabbit sinoatrial nodal cells?

<p>It decreases moderately. (B)</p> Signup and view all the answers

Which of the following statements about the effects of stretch on spontaneous depolarization time is true?

<p>It decreases significantly during stretch. (B)</p> Signup and view all the answers

Which of the following describes the control value of spontaneous depolarization rate in rabbit SAN pacemaker cells?

<p>0.115 V/s (C)</p> Signup and view all the answers

What specific mechanism is responsible for mechanotransduction in living cells as mentioned in the context?

<p>Chemical–mechanical synergism via PLC and PLA2 pathways (D)</p> Signup and view all the answers

Which type of animals were included in the study as models to analyze ventricular myocytes?

<p>Guinea pigs, rats, and humans with end-stage cardiac failure (C)</p> Signup and view all the answers

At which voltage was the amplitude of ISAC measured in the study?

<p>-45 mV (D)</p> Signup and view all the answers

What age differences were noted among the rat models used, specifically in SHR and WKY groups?

<p>2–3 months vs 15 months (A)</p> Signup and view all the answers

Which of the following is a known mechanosensitive channel referenced in the discussion?

<p>Mechanosensitive cation channel (MSCC) (D)</p> Signup and view all the answers

What role does the epoxyeicosatrienoic acid (EET) play in cellular signaling as described?

<p>It is involved in chemical-mechanical synergism (B)</p> Signup and view all the answers

Which of the following is associated with the stretch sensitivity observed in ventricular myocytes?

<p>Influence on calcium transient dynamics (D)</p> Signup and view all the answers

What does the term ISAC refer to in the context of cardiac myocyte response?

<p>Ionic stretch-activated current (A)</p> Signup and view all the answers

What is the effect of pre-cordial mechanical stimulation on cardiac rhythm?

<p>It can induce various rhythm disturbances. (D)</p> Signup and view all the answers

Which rhythm disturbance is associated with complete heart block as noted in the study?

<p>Complete heart block (CHB) (A)</p> Signup and view all the answers

What key parameter reflects the timing and influence of interventions on heart rhythm disturbances?

<p>Markers indicating intervention timing (D)</p> Signup and view all the answers

What impact is associated with the location of impact sites during sports activities?

<p>They can lead to sudden cardiac death through commotio cordis. (C)</p> Signup and view all the answers

Which observation was made regarding the ECG and left ventricular pressure during pre-cordial impact experiments?

<p>The ECG displayed distinct alterations in response to the impact. (C)</p> Signup and view all the answers

Which type of cardiac event results from the mechanosensitive response during sudden cardiac events in sports?

<p>Cardiac arrhythmias (C)</p> Signup and view all the answers

What is a notable consequence of mechanical stimulation identified in the cardiological study?

<p>Alterations in cardiac rhythm stability. (B)</p> Signup and view all the answers

Which of the following is an outcome associated with the impact of mechanical stimulation on the cardiac system?

<p>Variable response leading to multiple rhythm disturbances. (D)</p> Signup and view all the answers

What is the effect of cell-in-gel contraction on fractional shortening compared to load-free cells?

<p>Cell-in-gel contraction shows smaller fractional shortening. (A)</p> Signup and view all the answers

How does titin isoform expression affect calcium sensitivity in cardiac myocytes?

<p>Differences in titin isoform expression affect passive tension, which influences calcium sensitivity. (B)</p> Signup and view all the answers

What characteristic skeletal component was observed in the contraction behavior of myocytes in a gel versus a load-free environment?

<p>Slower relaxation in cell-in-gel compared to load-free. (C)</p> Signup and view all the answers

Which of the following statements is true about length-dependent calcium activation in fish cardiomyocytes?

<p>It permits a large operating range of sarcomere lengths. (A)</p> Signup and view all the answers

What measurement units were used to represent titin phosphorylation data?

<p>Arbitrary units. (C)</p> Signup and view all the answers

What type of tension is primarily determined by titin isoform expression and affects calcium sensitivity?

<p>Passive tension. (D)</p> Signup and view all the answers

Which of the following is a significant conclusion drawn from studies on myocyte contraction under different conditions?

<p>Load-free cell dynamics show better relaxation than gel-contracted cells. (C)</p> Signup and view all the answers

What effect does titin phosphorylation have on the differences observed in passive tension in the studied animal models?

<p>It impacts passive tension based on isoform type and phosphorylation state. (D)</p> Signup and view all the answers

What does the term 'late repolarization velocity' refer to in cardiac physiology?

<p>The rate of the secondary slow phase of repolarization. (D)</p> Signup and view all the answers

What is the primary consequence of mechanical stress on the action potential profile?

<p>Induction of spontaneous depolarization and extra-systoles. (C)</p> Signup and view all the answers

What does 'threshold to peak time' measure in cardiac action potentials?

<p>The time required to reach maximum systolic potential from the threshold. (C)</p> Signup and view all the answers

How does increased preload affect Ventricular Electric Remodeling (VER)?

<p>It can provoke changes in the action potential duration and heart rhythm. (D)</p> Signup and view all the answers

In the context of cardiac myocytes, what is the significance of the sinoatrial node (SAN)?

<p>It acts as the primary pacemaker, controlling heart rate and rhythm. (A)</p> Signup and view all the answers

What is the role of spontaneous depolarization time in cardiac action potentials?

<p>It reflects the interval from the maximum diastolic potential to the point of threshold re-establishment. (A)</p> Signup and view all the answers

What happens to membrane potential during stretch in cardiac myocytes?

<p>Membrane potential undergoes depolarization, leading to action potential prolongation. (C)</p> Signup and view all the answers

What does the 'mechanosensitive current' refer to in the context of cardiac myocytes?

<p>The electrical current generated in response to changes in mechanical strain. (B)</p> Signup and view all the answers

Flashcards

Mechano-Electric Feedback

A process where mechanical forces affect electrical activity, and vice-versa, in the heart.

Commotio Cordis

Sudden cardiac death caused by a specific chest impact.

Sudden Cardiac Death

Unexpected death caused by a sudden disturbance of the heart's rhythm.

ECG

Electrocardiogram: a graphical recording of the heart's electrical activity.

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Impact Sites (Sports)

Locational areas on the chest where impacts during sports are linked to commotio cordis.

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Heart Rhythm Disturbances

Abnormal patterns of electrical impulses leading to irregular heartbeats.

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Pre-cordial Mechanical Stimulation

A physical impulse applied to the chest area (in front of the heart), that can alter the heart's electrical activity.

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Cardiac Rhythm

The timing and sequence of electrical signals that drive the heart's contractions.

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Cardiac mechano-electric feedback

The interplay between mechanical (pressure or volume) changes and electrical activity in the heart.

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Afterdepolarizations

Abnormal electrical events occurring after the normal heart beat.

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Venous return

The volume of blood returning to the heart from the veins.

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Heart rate

The number of times the heart beats per minute.

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Blood pressure

The force of blood against the artery walls.

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Cardiac action potential

The electrical signal that causes the heart muscle to contract.

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Left ventricular volume pulses

Changes in the volume of the left ventricle of the heart.

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Electrophysiological effects

The effects that occur as a result of electrical events in the heart.

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Early Repolarization Velocity

The speed at which the heart cell's electrical potential returns to its resting state during the initial, fast phase of repolarization.

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Late Repolarization Velocity

The speed at which a heart cell's electrical potential returns to its resting state during the slower, secondary phase of repolarization.

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Spontaneous Depolarization Time

The time it takes for a heart cell's electrical potential to move from its most negative state (MDP) to the threshold level, where an action potential can be triggered.

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Threshold to Peak Time

The time it takes for a heart cell's electrical potential to reach its peak (MSP) after crossing the threshold level.

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Repolarization Time

The time taken for a heart cell's electrical potential to return from its peak (MSP) back to its most negative state (MDP).

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Action Potential

The electrical impulse that travels through heart cells, triggering muscle contraction.

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Mechanical Stress on Heart

The force applied to the heart muscle that can affect its electrical activity.

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Stretch-Induced Depolarization

When mechanical stretch of a heart cell makes it more likely to trigger an action potential.

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ISAC

An inward sodium current triggered by stretch in cardiac muscle cells, contributing to the heart's electrical activity.

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Stretch-Sensitivity

The degree to which a cell's electrical activity changes in response to mechanical stress.

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Nav Channel

A type of ion channel in cell membranes responsible for transmitting electrical signals by allowing sodium ions to pass through.

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Mechanotransduction

The process by which cells convert mechanical forces into electrical signals.

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PLC and PLA2 Pathways

Cellular signaling pathways that are involved in the process of mechanotransduction, converting mechanical stimuli into chemical signals.

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EET and HETE

Chemical messengers produced during mechanotransduction, influencing cell function and signaling.

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Deep Cytoplasm Events

Cellular processes that occur within the inner part of the cell, including the activation of signaling pathways and changes in gene expression in response to mechanical stimuli.

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Spontaneous Ca2+ Release

The release calcium ions (Ca2+) from the sarcoplasmic reticulum (SR) in a heart cell without an external trigger, leading to afterdepolarization.

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Sarcomere Length and Stability

The length of the sarcomere, the basic contractile unit in a muscle cell, influences the electrical stability of the heart cell. A shorter sarcomere leads to instability and increased risk of afterdepolarization.

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Mechano-Chemical Sensing

The ability of the heart cell to sense and respond to mechanical changes in its environment, linking mechanical forces to chemical signaling pathways.

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Preload Increase

An increase in the stretching of the heart muscle before contraction, resulting in a stronger contraction.

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Mechano-Chemo Transduction

The process by which mechanical stimuli in the heart are converted into chemical signals, leading to physiological changes.

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Nitric Oxide Synthases (NOS)

Enzymes that produce nitric oxide (NO), a signaling molecule involved in regulating cardiovascular function, including heart muscle relaxation and blood vessel dilation.

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nNOS

Neuronal nitric oxide synthase, an enzyme primarily found in nerves.

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L-NPA and L-NIO

L-NPA is a specific inhibitor of nNOS, while L-NIO is a specific inhibitor of eNOS. They help researchers study the roles of different NOS enzymes in heart function.

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CaT Peak

The highest point of the calcium transient, a surge in intracellular calcium levels that triggers heart muscle contraction.

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Spark # (100µm*s)

A measure of the number of calcium sparks, localized calcium release events within the heart, occurring in a specific area over a specific time.

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Cell Culturing for 3D Heart Studies

Growing heart cells in a gel-like matrix, allowing researchers to study the effects of mechanical forces on heart cell behavior in a controlled 3D environment.

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Electric Field Excitation

Stimulating heart cells with an electric field to trigger muscle contraction, mimicking the natural process of the heart.

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Stretch-Activated Currents

Electrical currents in heart cells triggered by mechanical stretching.

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Hypertrophy

Enlargement of heart muscle cells, often due to increased workload.

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Sinoatrial Node (SAN)

The heart's natural pacemaker; initiates the electrical impulse that controls heartbeat.

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Cycle Length

The time it takes for one complete heartbeat cycle.

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Maximum Systolic Potential

The highest electrical potential reached during the heart's contraction phase.

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Maximum Diastolic Potential

The lowest electrical potential reached during the heart's relaxation phase.

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What is 'Early Observation' in mechano-electric feedback?

The early observations of the impact of mechanical forces on the heart included the phenomena of commotio cordis and sudden cardiac death.

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What was the effect observed in ECG on the pig during impact?

The ECG recording of a pig subjected to a chest impact showed a change in heart rhythm, often leading to ventricular fibrillation.

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How does pre-cordial mechanical stimulation affect cardiac rhythm?

Pre-cordial mechanical stimulation can cause a variety of heart rhythm disturbances, including complete heart block, ST segment elevation, left bundle branch block, ventricular fibrillation, and non-sustained ventricular tachycardia.

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Mechanical Stimulation on Heart

The force applied to the heart muscle that can affect its electrical activity.

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Fractional Shortening (FS)

The percentage decrease in a muscle fiber's length during contraction. It reflects how much the muscle shortens relative to its resting length.

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Cell-in-Gel Contraction

The contraction of a heart cell embedded in a gel. This environment mimics the mechanical constraints experienced by heart cells in the heart.

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Load-Free Cell

A heart cell contracting without the restriction of surrounding tissues or a gel. Provides a baseline for comparing contraction strength.

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Knock-Down Factor

The difference in contraction strength between a cell-in-gel and a load-free cell. A higher knock-down factor suggests a stronger restriction from the gel.

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Alternans

An alternating pattern of heart beats, characterized by a strong beat followed by a weak beat. It can be an indicator of heart dysfunction.

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Sarcomere Length

The length of the basic contractile unit in a muscle cell. It influences the strength and speed of muscle contractions.

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Calcium Sensitivity

The responsiveness of muscle contraction to changes in calcium levels. Higher calcium sensitivity means a smaller change in calcium can trigger a stronger contraction.

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Passive Tension

The tension in a muscle fiber at rest, generated by the elastic proteins in the muscle. It influences how much calcium is needed to initiate contraction.

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Ventricular Electric Remodeling (VER)

Changes in the electrical activity of the heart's ventricles, often caused by mechanical stress or other factors.

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Action Potential (AP) Remodeling

Changes in the duration and shape of the electrical signal (action potential) that travels through heart cells.

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Epicardial, Midmyocardial, and Endocardial

These are different layers within the heart wall. Epicardial is the outermost layer, endocardial is the innermost, and midmyocardial is in between.

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APD Remodeling with Anterior Segment Pacing

Changes in action potential duration (APD) occur differently in various layers of the heart wall after pacing a specific area.

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Mechanical Stress and VER

Mechanical forces, like stretching, can affect the electrical activity of the heart, leading to ventricular electric remodeling.

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Stretch-sensitivity of ISAC

The change in the inward sodium current (ISAC) in cardiac muscle cells in response to stretching. This sensitivity can vary between different cell types and species.

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Known channels are mechanosensitive too

Many ion channels in cell membranes, including sodium (Nav) channels, are sensitive to mechanical forces. This means that stretch or pressure can affect how these channels function, influencing electrical signaling.

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What is mechanotransduction?

Mechanotransduction is the process by which cells convert mechanical forces (like stretch or pressure) into electrical signals. This is essential for many cellular processes, including heart function.

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How do mechanical forces affect heart cells?

Mechanical forces, like stretch or pressure, can affect the electrical activity of heart cells. This can lead to changes in heart rhythm, contractility, and overall function.

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What is the significance of mechanotransduction in heart health?

Understanding mechanotransduction is crucial for understanding heart health. It helps us comprehend how mechanical forces influence heart rhythm, contractility, and disease development, potentially leading to new therapies.

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Study Notes

Mechano-Electric Feedback

  • This is about mechano-electric coupling
  • The concept involves electrical dynamics, calcium dynamics, and contractile dynamics
  • These dynamics are interconnected in a feedback loop.

Early Observations

  • Early observations include commotio cordis and sudden cardiac death.
  • These events are related to chest impact during sports activities.

Chest Impact Sites

  • Common impact sites in sports activities leading to commotio cordis include baseball/softball, ice hockey pucks, and lacrosse balls, and also the knee.
  • These impact information is from a study of 22 cases

ECG and LVP Recording

  • ECG (Electrocardiogram) and LVP (Left Ventricular Pressure) recordings of an anesthetized pig subjected to a pre-cordial impact are presented.
  • The impact coincided with the upstroke of the T-wave.

Effects of Mechanical Stimulation

  • A diagram shows the effects of pre-cordial mechanical stimulation on cardiac rhythm.
  • The diagram shows complete heart block, ST-segment elevation, left bundle branch block, ventricular fibrillation, and non-sustained ventricular tachycardia.

Clinical observations

  • Observations are about Blood Pressure & Cardiac Action Potential

Relationship between pressure in radial artery and AP length

  • This refers to relationship between pressure in radial artery and action potential length for human patients.
  • Diagrams (A, B, C, and D) show different types of pressure-action potential length relationships.

Acute obstruction of the right ventricular outflow tract

  • The obstruction, caused by a balloon catheter, induces deflections resembling early after-depolarizations.
  • Diagrams (A) and (B) show these deflections.

Incremental left ventricular volume pulses

  • This study looks at incremental left ventricular volume pulses in an isolated rabbit heart with heart block.
  • Diagrams display the data.

Comparison of the effects of stretch and altered calcium handling

  • This section compares the effects of stretch and changes in calcium handling on cardiac cells.
  • Graphs illustrate early and late responses.

Schematic representation of the arrhythmogenic effects of mechanical activation

  • Diagram illustrates the potential arrhythmogenic effects of mechanical activation of cation-selective channels during early repolarisation.

Effect of increased venous return on heart rate & blood pressure

  • The impact of increased venous return on heart rate and blood pressure is explored in different positions (supine and legs elevated).
  • Data is summarized in a table.

Summary of electrophysiological effects of diastolic and systolic stretch

  • This section summarizes the electrophysiological effects of diastolic and systolic stretch on normal cardiac electrophysiology.
  • Diagrams illustrate the mechanisms.

The physics behind mechanical stretch

  • This section covers the physics behind mechanical stretch.
  • Diagrams include diagrams of stress versus strain graphs and viscoelastic models.

Stress Types in Mechanics

  • This section covers different types of stress and their categorization.
  • Illustrative diagram of stress hierarchies is included.

Mechanical stress in a cardiac myocyte

  • The study examines the mechanical stress within a cardiac myocyte.
  • Diagrams illustrate mechanical stress distribution.

Mechanical Stress is inhomogeneous

  • This section looks at the inhomogeneous mechanical stress within a mechanical system.
  • Diagrams show stress distributions.

What is the mechanism?

  • The presentation probes the mechanism behind early observations.

Gadolinium suppresses stretch-induced arrhythmia

  • This section focuses on how gadolinium can suppress stretch induced arrhythmia.
  • Diagrams display data in relation to concentration.

Extracellular potassium reverses stretch-induced depolarization

  • Extracellular potassium reverses the depolarizing effect of stretch on myocytes.
  • Diagrams shows variations in potassium concentrations and their effects on cell potential.

Patch clamp recording of an isolated cardiac myocyte

  • This section describes a patch-clamp experiment involving an isolated cardiac myocyte subjected to axial stretch.
  • The data is shown graphically.

Mechanically Induced Potential (MIP) in cardiac fibroblasts

  • The study examines the mechanically induced potential (MIP) in cardiac fibroblasts.
  • Diagrams illustrate data related to the results.

Events of the surface

  • This section analyzes the surface events in ventricular myocytes.
  • The analysis connects the increase in amplitude with hypertrophy.

Two mechanisms accounting for mechanotransduction

  • Two mechanisms underlying mechanotransduction in living cells are presented in diagrams.

Recording of spontaneous pacemaker activity

  • The study examines the pacemaker activity in isolated rabbit SAN cells in the absence and presence of stretch.
  • The results are presented in a diagram.

Stretch-induced changes of key electrophysiological parameters

  • This section includes a table that presents stretch-induced changes in electrophysiological parameters of spontaneously beating rabbit sinoatrial (SAN) pacemaker cells.

Mechanical stress modulates action potential profile

  • This study investigates how mechanical stress modulates the action potential profile in fish hearts.

Action potential recordings from single cells

  • Action potential recordings are presented from single cells from the heart surface.
  • Graphs illustrate the recordings..

Effect of filling pressure on hemodynamics

  • Study on the effect of filling pressure on the hemodynamic functions.
  • Diagrams illustrate the relationship between filling pressure and stroke volume and heart rate.

Effect of preload and afterload on ventricular electrical remodeling

  • Analysis of the effect of preload and afterload on ventricular electrical remodeling in different experimental groups.
  • The results are presented in graphs.

Stretch induces membrane depolarization, prolongation of the action potential, and extra-systoles

  • Stretch affects membrane depolarization and prolongs the action potential and causes extra-systoles.
  • Diagrams illustrate the data with visual representations.

Electrophysiological analysis of currents generated by MSCs

  • Electrophysiological study of the currents generated by MSCs.

Mechanical stimulation: local stretch of a ventricular myocyte

  • This experiment involves the mechanical stimulation and local stretch of a ventricular myocyte using images.

The mechanosensitive currents of heart

  • Analysis of mechanosensitive currents in the heart.

Whole cell current response to stretch

  • Study about the whole cell current response to stretch.
  • Diagrams represent the data graphically..

Stretch sensitivity of ISAC

  • Study on the stretch sensitivity of ISAC across different species and strains.
  • Results are presented graphically.

Known channels are mechanosensitive too

  • Channels are mechanosensitive.
  • Detailed look at the mechanosensitivity of sodium channels.
  • Illustrations depict recordings of the channels in response to stretch.

Models for MSCs

  • Models about MSCs.

Two mechanisms accounting for mechanotransduction

  • Analysis of two mechanisms behind mechanotransduction in living cells.
  • Diagrams illustrate these underlying mechanisms.

Chemical-mechanical synergism via PLC and PLA2 pathways

  • Study illustrates chemical-mechanical synergism via PLC and PLA2 pathways.
  • Diagram shows the pathways and related entities.

Events of the deep cytoplasm: mechanochemical sensing

  • This section discusses the events related to mechanochemical sensing in the deep cytoplasm.
  • Detailed diagrams illustrate the signaling pathways and entities involved.

Myocyte contraction

  • Study presents data from experiments on myocyte contraction involving gel, including microscopic images and graphs.

Knock-down factor in myocyte contraction

  • Study looks at the effects of a "knock-down factor" on myocyte contraction in experiments using a gel.
  • Graphical data on contraction is presented..

Enhanced length-dependent Ca2+ activation

  • Study on Ca2+ activation in fish cardiomyocytes, related to sarcomere length.

Active tension development and calcium sensitivity of rat and trout

  • Study on the active tension development and calcium sensitivity in rat and trout hearts as related to sarcomere length.
  • Data presented in multiple charts and graphs.

Passive tension determines calcium sensitivity

  • Data analysis on how passive tension determines calcium sensitivity in cardiac myocytes.
  • Graphical illustration of the findings.

Differences in passive tension

  • Study on passive tension differences due to titin isoform expression and phosphorylation.
  • Diagram showing quantitative differences in the two groups being studied.

Spontaneously Calcium Release Translated to Afterdepolarization

  • Diagrams and text describing mechanisms behind spontaneous Ca2+ release and afterdepolarizations.

Sarcomere length determines electric stability

  • Discusses how sarcomere length affects the electrical stability in cardiac myocytes.
  • Diagram illustrating the relationship between length and stability.

Events of the deep cytoplasm: mechanochemical sensing

  • Presentation of mechanochemical sensing events in the deep cytoplasm of cells.

Mechano-Chemo Transduction: Preload increase

  • Study on preload increase via stretching myocytes.
  • Diagrams and graphs are accompanying the analysis.

Electrophysiological basis for T-wave memory

  • Study on the electrophysiological basis for T-wave memory.
  • Diagrams of ECG and associated data are presented.

VER is dependent on direction of propagation

  • Discussion of how VER (ventricular electric remodeling) depends on the direction of propagation.
  • Study includes analysis of different pacing directions.

Circumferential strain as mechanism triggering VER

  • Study about circumferential strain as a mechanism triggering VER (ventricular electric remodeling).
  • Diagrams of strain and related data are presented.

VER is not due to structural remodeling

  • Study refutes the idea that VER (ventricular electric remodeling) is due to structural remodeling.
  • Images (microscopic) of tissue samples are provided.

Mechano-electric feedback induced VER

  • Study on mechano-electric feedback and its effect on VER.
  • Results, graphically represented, are included.

Mechanism of wall stretch in regional ischemia

  • Study about different mechanisms of wall stretch in regional ischemia.
  • Ischemic wall stretch is presented in diagrams.

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Mechano-Electric Feedback PDF

Description

This quiz explores the mechano-sensitive responses of the cardiac system during sports activities. It examines key concepts such as mechano-electric feedback, sudden cardiac death, and the significance of intervention timing on cardiac rhythm disturbances. Test your knowledge on the complex interactions within the heart's mechanics.

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