Structures and Functions of Cardiovascular

The heart is a pear shaped organ, positioned centrally within the chest cavity, with the apex extending over to the left nipple. The heart is divided into a right and left side, each side having an atrium and ventricle. The contraction of the heart pumps blood throughout the body. The right side receives oxygen poor blood from the major veins of the body, and pumps this blood into the lungs, where it is oxygenated. The left side of the heart then receives oxygen rich blood from the lungs, and pumps this blood through the arteries, into the body.

The heart conduction system is the network of nodes, cells, and signals that controls your heartbeat. Each time your heart beats, electrical signals travel through your heart. These signals cause different parts of your heart to expand and contract. The expansion and contraction control blood flow through your heart and body.

Our cardiac conduction system contains specialized cells and nodes that control your heartbeat. These are the:

• Sinoatrial node.
• Atrioventricular node.
• Bundle of His (atrioventricular bundle).
• Purkinje fibers.

Interventions 

The nurse should assess the pulses (eg, femoral, posterior tibial, dorsalis pedis) and skin color and temperature 

The MAP refers to the average pressure within the arterial system felt by the vital organs.  A normal MAP is between 70-105 mm Hg.  If the MAP falls below <60 mm Hg, vital organs may be underperfused and can become ischemic.

A normal MAP is 70-105 mm Hg.  The client with the BP of 106/42 mm Hg has a MAP of 63 mm Hg, in the abnormal range.  The nurse should report this to the HCP and monitor the client closely.

The basic life support sequence is compressions, airway, and breathing. High-quality CPR is associated with improved client outcomes and begins with high-quality chest compressions (ie, 100-120/min, 2-2.4 in [5-6 cm] deep).  Any unwitnessed collapse should be treated with 2 minutes of CPR, followed by activating the emergency response system and obtaining an automated external defibrillator.  If no shock is advised, the nurse should resume high-quality chest compressions immediately. 

Synchronized cardioversion is a procedure used to convert tachyarrhythmias (eg, supraventricular tachycardia, ventricular tachycardia) with a pulse to stable cardiac rhythms via transcutaneous electrical shock.  The shock in cardioversion is timed by the defibrillator (“sync” feature enabled) to be delivered only during the R wave of the QRS complex, when the ventricles depolarize. Prior to delivery of electrical shock (eg, cardioversion, defibrillation), oxygen should be turned off and moved away.  Oxygen is flammable and may explode when subjected to electric currents.

Defibrillator pads should be placed on the right upper chest next to the sternum and on the left lower chest.

Treatment includes vagal stimulation and drug therapy.  Common vagal maneuvers include Valsalva, coughing, and carotid massage.  IV adenosine is the drug of choice to convert SVT to a sinus rhythm.  If vagal stimulation and drug therapy are ineffective and the client becomes hemodynamically unstable, synchronized cardioversion is used.  Recurrent SVT may require radiofrequency catheter ablation.

Auscultation of the heart requires excellent hearing and the ability to distinguish subtle differences in pitch and timing. Hearing-impaired health care practitioners can use amplified stethoscopes. High-pitched sounds are best heard with the diaphragm of the stethoscope. Low-pitched sounds are best heard with the bell. Very little pressure should be exerted when using the bell. Excessive pressure converts the underlying skin into a diaphragm and eliminates very low-pitched sounds.

• An arterial bruit is a turbulent blood flow sound heard in a peripheral artery.
• A pericardial friction rub is a high-pitched, scratchy sound during S₁ or S₂ at the apex of the heart.  It is best heard with the client sitting and leaning forward and at the end of expiration.  It occurs when inflamed surfaces of the heart rub against each other.
• An S₃ gallop is an extra heart sound that occurs closely after S₂.  It is a low-pitched sound heard in early diastole that is similar to the sound of a horse’s gallop.  The mitral area is located at the fifth intercostal space, medial to the mid-clavicular line.

Major auscultatory findings include

• Heart sounds
• Murmurs
• Rubs

Heart sounds are brief, transient sounds produced by valve opening and closure; they are divided into systolic and diastolic sounds.

Murmurs are produced by blood flow turbulence and are more prolonged than heart sounds; they may be systolic, diastolic, or continuous. They are graded by intensity and are described by their location and when they occur within the cardiac cycle. Murmurs are graded in intensity on a scale of 1 to 6.

Rubs are high-pitched, scratchy sounds often with 2 or 3 separate components, which may vary according to body position; during tachycardia, the sound may be almost continuous.

You can listen the heart sounds HERE

Its important the measuring jugular venous pressure. Distension of jugular neck veins should be performed with the client sitting with the head of the bed at a 30- to 45-degree angle.  The nurse will observe for distension and prominent pulsation of the neck veins.  The presence of JVD in the client with heart failure may indicate an exacerbation and possible fluid overload.

Examination and Palpation of the Apical Impulse (Point of Maximal Impulse)

After examining the neck veins, the next step is to see if the apical impulse, also called the apex beat and point of maximal impulse (PMI) is visible in the vicinity of the fifth intercostal space. Not seeing it is usually a normal finding. You can check to see the apical impulse in forced expiration or in the left lateral decubitus position. You can also check after palpation.

Auscultate for a bruit

An aneurysm is an outpouching or dilation of a vessel wall.  An abdominal aneurysm occurs on the aorta.  A bruit, a swishing or buzzing sound that indicates turbulent blood flow in the aneurysm, is best heard with the bell of the stethoscope.  It may be auscultated over the aortic aneurysm in the periumbilical or epigastric area slightly left of the midline. Aortic abdominal aneurysm  (See in Common Pathologies)

Transvenous pacemaker. Discharge teaching for the client with a permanent pacemaker should include the following:

• Report fever or any signs of redness, swelling, or drainage at the incision site.
• Carry a pacemaker identification card and wear a medical alert bracelet.
• Take the pulse daily and report it to the health care provider (HCP) if below the predetermined rate.
• Avoid MRI scans, which can affect or damage a pacemaker.
• Avoid carrying a cell phone in a pocket directly over the pacemaker and, when talking on a cell phone, hold it to the ear on the opposite side of the pacemaker.
• Notify airport security of a pacemaker; a handheld screening wand should not be held directly over the device.

Cardiac catheterization helps assess and diagnose coronary artery disease (eg, coronary artery patency, atherosclerosis).  A catheter is advanced to the heart through a vein (eg, femoral, antecubital) for right-sided heart catheterization or an artery (eg, brachial, femoral) for left-sided heart catheterization.  After the procedure, a pressure dressing is applied and the client placed supine with the affected extremity flat for 2-6 hours to promote complete hemostasis.

The nurse monitors vital signs, extremity integrity (eg, pulses, sensation, capillary refill), and dressings for indications of bleeding according to institution policy.  If bleeding occurs, the nurse applies direct manual pressure to the vessel puncture site (ie, about 2.5 cm [1″] above the skin puncture site) to achieve hemostasis and keep the client hemodynamically stable.

Common pathologies 

Myocardial infarction, is a lack of blood flow can damage or destroy part of the heart muscle, its possible to observe ST elevation. A heart attack is also called a myocardial infarction. Prompt treatment is needed for a heart attack to prevent death. 

Myocardial Infarction Presentation

Ischemic chest pain

• Described as pressure, heaviness, tightness
• May radiate to jaw, arm, back, or upper abdomen
• Lasts more than 30 minutes
• Not improved with rest or position change
• Worsens with exertion

Associated symptoms

• Shortness of breath
• Nausea & vomiting
• Sweating
• Anxiety
• Indigestion
• Dizziness  
• Fatigue & weakness

Atypical presentation

• Associated symptoms with no chest pain
• More common in women, older adults & clients with neuropathy (diabetes)

Congestive Heart failure — sometimes known as congestive heart failure — occurs when the heart muscle doesn’t pump blood as well as it should. When this happens, blood often backs up and fluid can build up in the lungs, causing shortness of breath. It’s very useful the patient education.

What is the Difference Between Left and Right-Sided Heart Failure?

In IE (Infective endocarditis), the vegetations over the valves can break off and embolize to various organs, resulting in life-threatening complications.  These include the following:

1. Stroke – paralysis on one side
2. Spinal cord ischemia – paralysis of both legs
3. Ischemia to the extremities – pain, pallor, and cold foot or arm
4. Intestinal infarction – abdominal pain
5. Splenic infarction – left upper-quadrant pain

The nurse or the client (if at home) should report these manifestations immediately to the HCP.

IE commonly presents with fever, arthralgias (multiple joints pains), weakness, and fatigue.  These are expected and do not need to be reported during the initial stages of treatment.

IE clients typically require intravenous antibiotics for 4-6 weeks.  Fever may persist for several days after treatment is started.  If the client is persistently febrile after 1-2 weeks of antibiotics, this must be reported as it may indicate ineffective antibiotic therapy.

Splinter hemorrhages can occur with infection of the heart valves (endocarditis).  They may be caused by vessel damage from swelling of the blood vessels (vasculitis) or tiny clots that damage the small capillaries (microemboli).  The presence of splinter hemorrhages is not as critical as the macroemboli causing stroke or painful cold leg.

Raynaud phenomenon is a vasospastic disorder resulting in an episodic vascular response related to cold temperatures or emotional stress.  It most commonly affects women age 15-40.  Vasospasms induce a characteristic color change in the appendages (eg, fingers, toes, ears, nose).  When vasoconstriction occurs, the affected appendage initially turns white from decreased perfusion, followed by a bluish-purple appearance due to cyanosis.  Clients usually report numbness and coldness during this stage.  When blood flow is subsequently restored, the affected area becomes reddened and clients experience throbbing or aching pain, swelling, and tingling.  Acute vasospasms are treated by immersing the hands in warm water.

Client teaching regarding prevention of vasospasms includes:

Wear gloves when handling cold objects 

• Dress in warm layers, particularly in cold weather.
• Avoid extremes and abrupt changes in temperature.
• Avoid vasoconstricting drugs (eg, cocaine, amphetamines, ergotamine, pseudoephedrine).
• Avoid excessive caffeine intake 
• Refrain from use of tobacco products
• Implement stress management strategies (eg, yoga, tai chi) 

If conservative management is unsuccessful, clients may be prescribed calcium channel blockers to relax arteriole smooth muscle and prevent recurrent episodes.

Aortic stenosis is the narrowing of the orifice between the left ventricle and aorta.  Many clients with aortic stenosis are asymptomatic.  Symptoms usually develop with exertion as the left ventricle cannot pump enough blood to meet the body’s demands due to aortic obstruction (stenosis).  These include dyspnea, angina, and, in severe cases, syncope (reduced blood flow to the brain).  Clients usually do not experience symptoms at rest. This decreased ejection fraction results in a narrowed pulse pressure (ie, the difference between systolic and diastolic blood pressures) and weak, thready peripheral pulses.  With exertion, the volume of blood that is pumped to the brain and other parts of the body is insufficient to meet metabolic demands, resulting in exertional dyspnea, anginal chest pain, and syncope.On auscultation, aortic stenosis produces a loud, ejection systolic murmur over the aortic area as blood is ejected from the left ventricle through the stenosed aortic valve during systole.

An aortic aneurysm is a balloon-like bulge in the aorta, the large artery that carries blood from the heart through the chest and torso.

Aortic aneurysms can dissect or rupture:

• The force of blood pumping can split the layers of the artery wall, allowing blood to leak in between them. This process is called a dissection.
• The aneurysm can burst completely, causing bleeding inside the body. This is called a rupture.
• Dissections and ruptures are the cause of most deaths from aortic aneurysms.

Open aneurysm repair involves a large abdominal incision and requires cross-clamping the aorta proximally and distally to the aneurysm.  Establishing baseline data is essential for comparison with postoperative assessments.  The nurse should pay special attention to the character and quality of peripheral pulses and renal and neurologic status. Dorsalis pedis and posterior tibial pulse sites should be marked for easy location postoperatively.  A decreased or absent pulse with cool, pale, mottled, or painful extremity postoperatively can indicate embolization or graft occlusion.  Graft occlusion may require reoperation.

Peripheral arterial disease (PAD) in the legs or lower extremities is the narrowing or blockage of the vessels that carry blood from the heart to the legs. It is primarily caused by the buildup of fatty plaque in the arteries, which is called atherosclerosis. PAD can happen in any blood vessel, but it is more common in the legs than the arms.Absence of hair growth on the lower extremities is more specific for peripheral artery disease.

A deep venous thrombosis (DVT) is a blood clot (ie, thrombus) formed in large veins, generally of the lower extremities.  DVTs occur commonly as a result of decreased activity or mobility (eg, prolonged travels, bed rest) or as a complication of hospitalization or surgery. Occurs when a clot becomes lodged in a vein, most often in the deep veins of the lower extremities due to venous stasis, endothelial damage, and hypercoagulability of blood (Virchow triad).

Although clients with a DVT may have no symptoms, typical clinical manifestations include unilateral edema, localized pain (eg, calf pain) or tenderness to touch, warmth, erythema, and occasionally low-grade fever. Treatment of a VTE includes anticoagulants (eg, enoxaparin, rivaroxaban, heparin, warfarin) to prevent further clotting as the body’s fibrinolytic system naturally dissolves the clot by breaking down fibrin deposits.

Transgender women clients are often prescribed antiandrogen medications (eg, spironolactone) to reduce androgen levels (eg, testosterone) and estrogen therapies to induce feminizing traits (eg, breast enlargement, reduction in body hair, decrease in testicular size and erectile function).

Estrogen places clients at an increased risk for developing blood clots, due to hypercoagulability, and therefore adverse thrombotic events (eg, stroke, myocardial infarction, venous thromboembolism).  Signs and symptoms of deep venous thrombosis (eg, leg swelling, redness, pain) should be reported to the health care provider (HCP) immediately 

Clients with DVT are at risk for developing a life-threatening pulmonary embolism (PE).  The clot may become dislodged by massage or use of sequential compression devices on the affected extremity.  The nurse would intervene immediately if a client was observed massaging the site because this may trigger an embolism. 

Chronic venous insufficiency (CVI) occurs when the valves in the veins of the lower extremities consistently fail to keep venous blood moving forward, which causes chronic increased venous pressure.  The increased pressure pushes fluid out of the vascular space and into the surrounding tissues, where tissue enzymes break down red blood cells.

The destruction of red blood cells releases hemosiderin (a reddish-brown protein that stores iron), which causes a brownish skin discoloration; chronic edema and inflammation cause the tissue to harden and appear leathery.

Acute pericarditis is inflammation of the membranous sac (pericardium) surrounding the exterior of the heart, which can cause an increase in the amount of fluid in the pericardium (ie, pericardial effusion).  Increased pericardial fluid places pressure on the heart, which impairs the heart’s ability to contract and eject blood.  This complication (ie, cardiac tamponade) is life-threatening without immediate intervention.

When assessing clients with pericarditis, it is critical for the nurse to observe for signs of cardiac tamponade (eg, muffled or distant heart tones, hypotension, jugular venous distension) 

Mitral valve regurgitation is the result of a disrupted papillary muscle(s) or ruptured chordae tendineae, allowing a backflow of blood from the left ventricle through the mitral valve into the left atrium.  This backflow can lead to dilation of the left atrium, reduced cardiac output, and pulmonary edema.  Clients are often asymptomatic but are instructed to report any new symptoms indicative of heart failure (eg, dyspnea, orthopnea, weight gain, cough, fatigue).  This client should be assessed first due to possible heart failure, which would require immediate intervention.

Common Cardiac Rhythms 

Supraventricular tachycardia (SVT) is a dysrhythmia that originates from an ectopic focus above the bifurcation of the bundle of His.  The heart rate can be 150-220/min.  The rhythm is usually regular.  P waves are often hidden.  If visible, they may have an abnormal shape and the PR interval may be shortened.  The QRS complex is usually narrow (<0.12 second).

Stimulants (eg, nicotine, caffeine, cocaine) and organic heart disease can cause SVT.  Clinical significance depends on the client’s symptoms.  A prolonged episode of SVT with a heart rate >180/min will cause decreased cardiac output and hypotension.  The client may also experience palpitations, dyspnea, and angina.

Useful information

Medications 

The use of any nonsteroidal anti-inflammatory drugs (NSAIDS) is contraindicated as they contribute to sodium retention, and therefore fluid retention 

Aspirin, an antiplatelet agent, inhibits platelet aggregation, prevents thrombus formation, and reduces heart inflammation.  Clients without signs of bleeding or low platelet levels may safely receive aspirin. We can use on Myocardial infarctions (MIs) damage heart muscle and require medications to improve heart function and prevent reinfarction (eg, aspirin).  

Atorvastatin is a lipid-lowering medication given to clients to lower cholesterol levels (ie, LDL cholesterol), which reduces plaque and reinfarction risk.  However, statins may cause rhabdomyolysis and require monitoring for muscle weakness and pain.

Docusate sodium is a stool softener that reduces straining during bowel movements, thereby decreasing the workload on the heart.  Straining can also cause bradycardia due to vagal response.

Lisinopril is an ACE inhibitor often prescribed to clients after an MI to prevent ventricular remodeling and progression of heart failure.  Lisinopril may cause hyperkalemia and hypotension, and should be administered only to clients with normokalemia and normotension.

Metoprolol is a beta blocker prescribed to clients after MI to reduce the risk of reinfarction and heart failure.  Metoprolol lowers blood pressure and heart rate; therefore, the nurse should hold the medication and notify the health care provider of hypotension or a heart rate <50/min. 

Others Cardiac Rhythms

• Atrial Fibrillation
• Atrial Flutter
• Sinus Tachycardia
• Ventricular Taquycardia
• Asystole
  • Reversible causes of asystole / pulseless electrical activity.

You can learn more in our EKG course HERE