Srg Feb2017 Comprehensive Exam 3: Cardiac Anatomy, Physiology, Conditions, Assessment And Management

The P wave in an ECG represents the depolarization of the atria. Depolarization is the process by which the cardiac muscle cells lose their electrical charge, allowing them to contract and pump blood. In the case of the P wave, it specifically represents the depolarization of the atrial muscle cells, which initiates the contraction of the atria and the subsequent filling of the ventricles. This electrical activity can be detected and recorded by the ECG, providing valuable information about the functioning of the heart.

Chest pain is the most common symptom of myocardial infarction, also known as a heart attack. During a heart attack, there is a blockage in the blood vessels that supply the heart muscle with oxygen and nutrients. This lack of blood flow can cause severe chest pain, often described as a squeezing or pressure sensation. The pain may radiate to the left arm, jaw, or back. It is important to recognize and seek medical attention for chest pain, as it can be a sign of a life-threatening condition.

The pulmonary veins deliver blood to the left atrium. The coronary sinus drains blood from the heart muscle itself and delivers it to the right atrium. The superior vena cava carries deoxygenated blood from the upper body to the right atrium, while the inferior vena cava carries deoxygenated blood from the lower body to the right atrium. Therefore, only the pulmonary veins deliver blood to the left atrium.

Chordae tendinae are strong connective tissue strings that are attached to papillary muscles and to the cusps of the atrioventricular valves. They help to anchor the valves and prevent them from inverting into the atria during ventricular contraction. This allows for proper blood flow through the heart and prevents backflow of blood. Musculi pectinati are ridges of muscle in the atria, trabeculae carneae are muscular projections in the ventricles, and the skeleton of the heart refers to the fibrous tissue that provides structural support to the heart.

Stokes-Adams Syndrome refers to a condition where patients experience periodic fainting after a few seconds of complete AV block. This syndrome is characterized by a sudden loss of consciousness due to a temporary interruption in the electrical signals that control the heart's rhythm. During a complete AV block, the electrical signals that normally travel from the atria to the ventricles are blocked, leading to a pause in the heart's activity. This pause can cause a drop in blood pressure and inadequate blood flow to the brain, resulting in fainting episodes. Therefore, Stokes-Adams Syndrome is the appropriate term to describe this condition.

If the SA node becomes damaged and nonfunctional, another part of the heart, possibly the AV node, will become the pacemaker. The SA node is responsible for initiating the electrical impulses that regulate the heart's rhythm. However, if it is unable to function properly, the AV node, which is located in the atria, can take over the role of pacemaker and generate the electrical signals to stimulate the contraction of the ventricles. This allows the heart to continue beating, although the rhythm may be slower or irregular compared to when the SA node is functioning properly.

Excessive parasympathetic stimulation is most likely to cause bradycardia. The parasympathetic nervous system is responsible for slowing down the heart rate, and when it is overstimulated, it can cause the heart to beat at a slower rate than normal. This can be due to various factors such as certain medications, vagal maneuvers, or medical conditions like hypothyroidism.

Rheumatic fever, which leads to rheumatic heart disease, is caused by an autoimmune response to a Group A streptococcal infection. When the body is infected with Group A streptococcus bacteria, the immune system produces antibodies to fight off the infection. However, in some cases, these antibodies mistakenly attack the body's own tissues, particularly the heart, joints, and other organs, leading to rheumatic fever. This condition can cause inflammation and damage to the heart valves, leading to rheumatic heart disease. Therefore, the correct answer is Group A streptococcal infection.

Tetralogy of Fallot is the most common form of blue baby syndrome. This condition is characterized by four heart defects that affect the flow of oxygenated blood to the body. These defects include a ventricular septal defect, pulmonary stenosis, overriding aorta, and right ventricular hypertrophy. As a result, inadequate amounts of oxygenated blood are circulated to the body, leading to cyanosis or a bluish discoloration of the skin. This condition typically requires surgical intervention to correct the heart defects and improve blood flow.

Cholinergic stimulation of the heart will not increase the resting heart rate. Cholinergic stimulation refers to the activation of the parasympathetic nervous system, which is responsible for slowing down the heart rate. Therefore, instead of increasing the heart rate, cholinergic stimulation will have the opposite effect and decrease the resting heart rate.

Stimulation of the CN X (vagus nerve) will result in decreased heart rate. The vagus nerve is responsible for parasympathetic innervation of the heart, which means it helps to slow down the heart rate. When the vagus nerve is stimulated, it releases neurotransmitters that inhibit the electrical activity of the heart, leading to a decrease in heart rate. This can be useful in certain situations, such as when the heart rate is too fast and needs to be slowed down.

Atherosclerosis is a condition characterized by the buildup of plaques inside the arteries. These plaques are made up of cholesterol, fat, calcium, and other substances. Over time, these plaques can become hardened and narrow the arteries, obstructing the flow of blood. This can lead to reduced blood flow to the coronary arteries, which supply the heart muscle with oxygen and nutrients. As a result, atherosclerosis can cause chest pain (angina), heart attack, or other cardiovascular complications. Therefore, the correct answer is "Plaques obstruct the artery."

Distended jugular veins are not associated with left-sided heart failure. Left-sided heart failure typically leads to fluid accumulation in the lungs, causing symptoms such as exertional dyspnea (shortness of breath during physical activity) and orthopnea (shortness of breath when lying flat). Cyanosis, a bluish discoloration of the skin and mucous membranes, may also be present due to inadequate oxygenation. However, distended jugular veins are more commonly associated with right-sided heart failure, where fluid backs up into the systemic venous circulation, leading to jugular vein distension.

During the period of ejection in the cardiac cycle, the atrioventricular valves are closed to prevent the backflow of blood from the ventricles to the atria. At the same time, the semilunar valves are open to allow the blood to be ejected from the ventricles into the arteries. This ensures that blood flows in the correct direction, from the heart to the rest of the body.

Beta-adrenergic blockers protect the ischemic myocardium by blocking catecholamines and sympathetic nerve stimulation. Catecholamines, such as adrenaline, increase heart rate and contractility, which can worsen ischemia. By blocking the effects of these substances, beta-adrenergic blockers reduce heart rate and contractility, thereby decreasing the oxygen demand of the myocardium and improving blood flow to the ischemic tissue. This helps to protect the heart from further damage during an ischemic event. Calcium channel blockers, narcotics, and nitrates do not have the same mechanism of action and do not specifically target catecholamines and sympathetic nerve stimulation.

The correct answer is ductus arteriosus. In a fetus, the ductus arteriosus is a temporary blood vessel that allows blood to bypass the lungs. It connects the pulmonary trunk to the aorta, allowing oxygenated blood to be shunted directly to the body. After birth, the ductus arteriosus typically closes, redirecting blood flow to the lungs for oxygenation.

The portion of the intrinsic conduction system located in the interventricular septum is the bundle of His and its branches. The bundle of His is a collection of specialized cardiac muscle fibers that transmit electrical impulses from the atrioventricular (AV) node to the Purkinje fibers, which then distribute the electrical signals to the ventricles. This pathway ensures coordinated and efficient contraction of the ventricles, allowing for effective pumping of blood throughout the body. The SA node, AV node, and Purkinje fibers are also part of the intrinsic conduction system, but they are not located specifically in the interventricular septum.

Cardiac muscle has a prolonged period of slow repolarization called the plateau phase. During this phase, the action potential is sustained, allowing the heart to contract and pump blood efficiently. This prolonged repolarization period helps to prevent tetanic contractions and allows the heart to relax and fill with blood before the next contraction. This characteristic of cardiac muscle is important for maintaining the coordinated and rhythmic contractions of the heart, ensuring proper blood flow throughout the body.

The mean arterial pressure (MAP) is calculated by adding one-third of the difference between the systolic and diastolic blood pressure to the diastolic blood pressure. In this case, the difference between the systolic and diastolic blood pressure is 30 mmHg (90 - 60 = 30). One-third of this difference is 10 mmHg (30 / 3 = 10). Adding this to the diastolic blood pressure of 60 mmHg gives us a MAP of 70 mmHg.

Congestive Heart Failure is a complex of clinical syndrome that can result from any structural or functional cardiac disorders that impairs the ability of the ventricles to fill or eject blood. This condition occurs when the heart is unable to pump enough blood to meet the body's needs. It can be caused by conditions such as coronary artery disease, high blood pressure, or heart valve disease. Symptoms of congestive heart failure include shortness of breath, fatigue, and swelling in the legs and ankles. Treatment may involve lifestyle changes, medication, or surgery depending on the underlying cause.

A prolonged P-R interval is a characteristic feature of incomplete primary AV heart block. In this condition, there is a delay in the conduction of electrical impulses from the atria to the ventricles, resulting in a longer than normal P-R interval on an electrocardiogram (ECG). This delay can cause symptoms such as dizziness, fainting, and palpitations. Incomplete AV block means that not all of the electrical impulses are blocked, allowing some to still reach the ventricles and produce a QRS complex. Inverted T waves and absent QRS complexes are not characteristic features of incomplete primary AV heart block.

Ach refers to acetylcholine, which is the neurotransmitter released during vagal stimulation of the heart. Acetylcholine binds to muscarinic receptors in the heart, leading to a decrease in heart rate. This is because activation of the parasympathetic nervous system, which is mediated by acetylcholine, opposes the sympathetic nervous system's effects on the heart, resulting in a decrease in heart rate.

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In phase II of cardiac rehabilitation, patients are ready to start aerobic exercise protocols. This phase typically begins a few weeks after a cardiac event or surgery, when the patient's condition has stabilized. During phase II, patients are closely monitored by healthcare professionals as they gradually increase their exercise intensity and duration. This phase aims to improve cardiovascular fitness, reduce the risk of future cardiac events, and enhance overall physical well-being.

In the presence of SA block, the electrical signals from the sinoatrial (SA) node are not transmitted properly to the atria. This results in a delay or absence of the P wave on the ECG tracing. The P wave represents atrial depolarization, which is the contraction of the atria. Therefore, in the presence of SA block, the P wave suddenly ceases or is not visible on the ECG tracing.

ST elevation is observed in the chronic stage of myocardial infarction (MI) or the "infarction stage". This is because during an MI, there is an obstruction in the blood flow to the heart muscle, leading to the death of the affected tissue. As the tissue heals, scar tissue forms, causing the ST segment to elevate on an electrocardiogram (ECG). This ST elevation is a characteristic finding in the chronic stage of MI and helps in diagnosing and monitoring the condition.

The aortic valve is located in the 2nd right intercostal space (ICS) near the medial end of the costal cartilage. This is the correct answer because the aortic valve is best heard in this area during auscultation. The 2nd left ICS near the sternal border is where the pulmonic valve is heard. The 5th left ICS near the sternal border is where the tricuspid valve is heard. The right lower end of the sternum is where the mitral valve is heard.

The correct sequence during a cardiac cycle is as follows:
1. Atrial systole: This is when the atria contract, pushing blood into the ventricles.
2. Rapid ejection: This is when the ventricles contract and blood is rapidly ejected into the aorta and pulmonary artery.
3. Reduced ventricular filling: This is when the ventricles start to relax and the pressure in the ventricles decreases, causing a decrease in blood flow into the ventricles.
4. Isovolumetric relaxation: This is when the ventricles fully relax and all heart valves are closed, preventing any blood flow into or out of the ventricles.

Gap junctions are the correct answer because they are specialized channels that allow for direct electrical communication between adjacent cardiac muscle cells. These channels facilitate the spread of action potentials, allowing for coordinated contraction of the myocardium. Transverse tubules are invaginations of the cell membrane that help transmit action potentials into the interior of the muscle cell. Sarcoplasmic reticulum is a network of membranous sacs that stores and releases calcium ions, which are necessary for muscle contraction. Intercalated discs are specialized regions where adjacent cardiac muscle cells are connected, but they do not directly facilitate the spread of action potentials.

Both transposition of the great vessels and total anomalous pulmonary venous return are classified under CYANOTIC congenital heart disease (CHD), not ACYANOTIC congenital heart disease (CHD). ACYANOTIC CHD refers to heart conditions that do not cause cyanosis (bluish discoloration of the skin due to low oxygen levels in the blood), whereas CYANOTIC CHD causes cyanosis. Coarctation of the aorta, on the other hand, is classified under ACYANOTIC CHD.

The correct answer is "Defer. Low WBC." This is because a low white blood cell count (WBC) can indicate a weakened immune system, which may put the patient at risk for infection. In the context of a patient who underwent sternotomy, it is important to ensure that their immune system is functioning properly before proceeding with any further medical interventions. Therefore, it would be appropriate to defer any additional procedures or treatments until the WBC count improves.

The left atrium is not part of the diaphragmatic or inferior surface of the heart. The diaphragmatic surface refers to the part of the heart that is in contact with the diaphragm, while the inferior surface refers to the lower part of the heart. The left atrium is located posteriorly and superiorly in the heart, and it does not contribute to the diaphragmatic or inferior surface.

The ejection fraction is a measure of the percentage of blood pumped out of the heart with each heartbeat. It is calculated by dividing the stroke volume (SV) by the end-diastolic volume (EDV). In this case, John has a SV of 72mL/beat and an EDV of 140mL. The ejection fraction can be calculated as (72/140) x 100 = 51.4%. A normal ejection fraction typically ranges from 50% to 70%. Since John's ejection fraction falls within the normal range, it suggests that his heart is functioning normally and not indicative of heart failure.

Increased venous return in the heart refers to an increase in the amount of blood returning to the heart from the body. This increased volume of blood stretches the walls of the heart, leading to an increase in the preload, which is the amount of blood in the ventricles just before contraction. As a result, the heart is able to contract more forcefully, leading to an increased force of contraction. This increased force, along with the increased preload, ultimately leads to an increase in stroke volume, which is the amount of blood pumped out of the heart with each beat. Therefore, the correct answer is AOTA, as all of these factors are interrelated and increase in response to increased venous return.

A 3rd degree AV Heart Block is characterized by a complete block of the electrical impulses from the atria to the ventricles. This means that the atria and ventricles are not synchronized in their contractions. Instead, the ventricles establish their own signal to maintain a regular heartbeat. This can lead to a slow heart rate and symptoms such as dizziness, fainting, and fatigue. Treatment may involve the use of a pacemaker to regulate the heart rhythm.

Kounis Angina is triggered by the release of inflammatory mediators following an allergic insult leading to coronary artery spasm. This type of angina is characterized by chest pain and other symptoms due to the constriction of the coronary arteries, which reduces blood flow to the heart. It is often associated with allergic reactions, such as those caused by medications, insect bites, or food allergies. The release of inflammatory mediators during an allergic reaction can cause the coronary arteries to spasm, leading to reduced blood flow and the development of angina symptoms.

The second left intercostal space along the left sternal border corresponds to the area where the pulmonic valve is heard. This valve is located between the right ventricle and the pulmonary artery, and its function is to prevent the backflow of blood from the pulmonary artery into the right ventricle. Therefore, if a murmur is heard in this specific area, it is likely due to an abnormality or dysfunction of the pulmonic valve.

The left coronary artery originates from the left aortic sinus at the base of the ascending aorta. This is where the artery branches off and supplies blood to the left side of the heart.

Resistance training is allowed 1 month after CABG (Coronary Artery Bypass Grafting) because it allows enough time for the sternum to heal and the patient to recover from the surgery. PTCA (Percutaneous Transluminal Coronary Angioplasty) is a less invasive procedure compared to CABG, so resistance training is allowed 1 day after PTCA. UE ergometer (Upper Extremity Ergometer) is a low-intensity exercise that can be started 5 days after sternotomy, which is a surgical incision made during CABG. Mild stretching of pectorals is allowed 2 days after CABG to promote flexibility and prevent muscle tightness.

Counting repetitions during resistance exercises can help decrease myocardial oxygen demand by decreasing both preload and stroke volume (SV). Preload refers to the amount of blood returning to the heart, and counting repetitions can help maintain a steady flow of blood back to the heart, reducing the strain on the heart. Additionally, counting repetitions can help regulate breathing and prevent breath-holding, which can further decrease preload and SV. Therefore, by counting, Erica can help decrease the workload on her heart during cardiac rehabilitation.

Early repolarization of cardiac muscle cells occurs when voltage-gated K+ ion channels open and voltage-gated Na+ ion channels close. This is because during the repolarization phase, the cell membrane potential is restored to its resting state by the efflux of K+ ions out of the cell and the closure of Na+ ion channels, which stops the influx of Na+ ions. Therefore, both options B and C are correct.

The correct answer is "Both the parietal and visceral serous pericardium are supplied by the vagus nerve." This statement is incorrect because the vagus nerve does not supply the serous pericardium. The serous pericardium is supplied by the phrenic nerves. The vagus nerve primarily supplies parasympathetic innervation to the heart.

The heart lies obliquely in the mediastinum, which is the space between the lungs in the chest. Its base is directed anteriorly and slightly superiorly, while its apex is directed posteriorly and slightly inferiorly. Additionally, two-thirds of the heart's mass lies to the right of the midline of the sternum.

The group of symptoms that indicate a ruptured abdominal aneurysm includes severe lower back pain, decreased blood pressure (BP), decreased red blood cell (RBC) count, and increased white blood cell (WBC) count. Severe lower back pain is a common symptom of a ruptured abdominal aneurysm. Decreased BP can occur due to internal bleeding caused by the rupture. Decreased RBC count indicates blood loss, while an increased WBC count suggests an inflammatory response to the rupture.

Ca2+ ions are primarily responsible for the depolarization phase of the action potential in pacemaker cells. During this phase, Ca2+ ions enter the cells, causing the membrane potential to become more positive. This influx of Ca2+ ions triggers the opening of voltage-gated ion channels, leading to the generation of an action potential. The movement of K+ ions, Na+ ions, and Cl- ions also play a role in the action potential, but Ca2+ ions have the most significant contribution to the depolarization phase.

The epicardium is the outermost layer of the heart wall and is also known as the visceral pericardium. It is a thin, protective layer that covers the heart and helps to reduce friction as the heart beats. It is not the pacemaker of the heart, which is the sinoatrial (SA) node. The parietal pericardium is a different layer that lines the pericardial sac, not the heart chambers. Therefore, the correct answer is that the epicardium is the visceral pericardium.

The common site of aortic aneurysm is the abdominal aorta. Aortic aneurysm refers to the abnormal enlargement or bulging of the aorta, which is the largest artery in the body. It commonly occurs in the abdominal aorta, which is the portion of the aorta that runs through the abdomen. Aortic aneurysms can also occur in other parts of the aorta, such as the ascending aorta, descending thoracic aorta, or arch of the aorta, but the abdominal aorta is the most frequent site.

Arrhythmias are the most common complication of a myocardial infarction. During a heart attack, the blood supply to a part of the heart muscle is blocked, leading to damage. This damage can disrupt the normal electrical signals that control the heart's rhythm, causing abnormal heart rhythms or arrhythmias. Arrhythmias can range from mild palpitations to life-threatening conditions such as ventricular fibrillation. Prompt medical intervention is crucial to manage and treat arrhythmias after a myocardial infarction to prevent further complications and improve patient outcomes.

The heart valves have a double layer of endocardium with a layer of connective tissue in between. The endocardium is the innermost layer of the heart, which lines the chambers and covers the valves. It is composed of a thin layer of endothelial cells and connective tissue. The connective tissue layer provides support and strength to the valves, allowing them to open and close efficiently to regulate blood flow.

During the period of ejection, the left ventricular pressure reaches a high point of approximately 120 mm Hg. This is because the left ventricle contracts forcefully to pump blood out to the rest of the body. The contraction of the left ventricle creates pressure that pushes the blood through the aortic valve and into the aorta. This pressure is necessary to overcome the resistance in the systemic circulation and ensure adequate blood flow to the organs and tissues. Therefore, a high pressure of approximately 120 mm Hg is required during ejection.