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Basic Blood Flow
  • Blood from the head, neck and thorax areas enters the atrium via the superior vena cava. The rest of the blood from the rest of the body enters the atrium via the inferior vena cava.
  • The blood from the right atrium passes the tricuspid valve to empty its contents into the right ventricle.
  • From the right ventricle blood flows through the pulmonary valves into the lungs where CO2 is released and O2 is received. The oxygenated blood then flows through the left atrium.
  • From the left atrium, blood passes the mitral valve into the left ventricle.
  • From the left ventricle, blood is pumped out through the aortic valve through the whole body.

 

            Note: (1) To help remember which valve is close to which atrium. From Right atrium blood passes the Tricuspid (alphabetically, T is next to R)

                        From Left atrium blood passes the Mitral valve (M is next to L).

(2) All arteries carry blood Away from the heart and all veins carry blood to the heart.


Normal Conduction System of the Heart

  • Think of this as the “battery” of the car and the heart chambers as the mechanical portion of the car. The car will not start without the battery that will “ignite” the car engine. In the same manner, the heart chambers will not function without the necessary “electricity” to make the heart chambers contract and pump blood.

 

     Normal heart conduction flow:

  1. SA node -   It is the hearts normal pacemaker since it excites itself under normal conditions. The cells in the SA node are all self-excitory cells, that is they have automaticity, the cell can excit themselves. Located in the junction of the superior vena cava and the right atrium.
  2. From the SA node, the impulse travels to the AV node,, which is located near the tricuspid valve.
  3. Impluse then travels to the Bundle of HIS
  4. The Bundle of His divides into the Left and Right Bundle Branches.
  5. From the bundle branches, the impulse travels to the Purkinje fibers, spread into the ventricular myocardium.
  • The cycle is repeated.  Any disturbance in the conduction system results into dysrhythmias. See ECG topic, which discusses certain heart dysrhythmias. NOTE: NCLEX will not go into details about the different heart rhythms but is important to know normal sinus and its components. Below is sample of a normal sinus rhythm on an ECG paper.

 

 

A normal sinus rhythm consists of:

   

P       =          Atrial depolarization (Systole)

PR     =          Measured from the beginning of tthe P wave through the end of the P or the beginning of QR

=          The electricity leaves the SA node and travels to the AV node

=          0.12 – 0.20 seconds (impulse from SA node à AV node and about 3 -5 small boxes on the ECG strip)

QRS   =          indicates Ventricular depolarization

=          0.06 – 0.12 seconds (about 2-3 small boxes on an ECG strip). If QRS is less than 0.06 is referred to as a narrow complex.

T wave             =          Ventricular repolarization (diastole) Atrial repolarization  - not seen but present;  buried in the QRS

U wave            =          Not usually seen;  Repolarization of the Purkinje fibers

 

            Basic Way to Analyze the ECG or rhythm strip.

            1.         Evaluate the P wave:

                                    (a)     Determine if it is present or not.

                                    (b)     Look at its shape.

                        P wave in a normal sinus usually appears round and is present. Yet, it can also appear inverted.

            2.         Count the number of R waves in a 6 second strip and multiply that number by 10. Normal heart rate = 60 – 100 bpm.

            3.         Look at the pattern or rhythm = Either it is regular or irregular.

            4.         Look at the PR (SA node to AV node) interval – Determine if it is constant

                                    PR interval is measured from the beginning of the P up to the beginning of the R wave.

                                    Normal PR interval = 0.12 – 0.20 seconds (about 3 – 5 small boxes)

            5.         Look at the QRS (ventricular depolarization) width. A normal sinus rhythm shows the QRS follows the P wave.

                                    Normal QRS = 0.06 – 0.12 seconds. A QRS less than .06 seconds is called a narrow complex.

 

 

Lead Placement (This may not be in the NCLEX but helps to know where to place leads when asked to do an EKG on a patient)

A lead is a like a picture of the electrical activity of the heart obtained by using wire combinations from a particular angle across the body. 

To obtain a 12 lead ECG, 4 wires are attached to the limbs (one each on both arms and one each on both legs), and six wires placed around the chest. NOTE: When choosing a site on the arms and legs for electrode, one is not limited to wrists and ankles. Moving closer to the heart (shoulders and groin) can help obtain a stronger signal, plus you are less likely to pick up skeletal, muscular interference or tremor.

Chest placement of the six chest wires are as follows:

  • V1 - Fourth intercostal space, right sternal border. It is an important starting point. It is best to run ones finger down the sternum until a bony horizontal ridge (angle of Louis – easier in males) is found. When found, move ones finger to the patient’s right and drop into the 2nd intercostal space. Then, move down the fourth intercostal space to place V1. 
  • V2 - Fourth intercostal space, left sternal border.
  • V3 - Midway between V2 and V4.
  • V4 - Fifth intercostal space, left midclavicular line.
  • V5 – Alligned with V4, left anterior axillary line.
  • V6 – Alligned with V4, left mid axillary line.

Note that in female patients electrodes are NEVER placed on top of the breast.

Meanwhile, when using a 5 wire lead, the leads are place as follows on the chest wall:

            Black   -           Upper left chest wall of the patient
            White -             Upper right chest wall of the patient
            Red      -           Lower left of the patient
            Green   -           Lower right of the patient
            Brown  -           Sternal area

 

Cardiac Physiology

  • Afterload - the tension or the pressure produced by a chamber of the heart, usually assumed to be the left ventricle, in order to contract and generate enough blood out of the chamber.  Afterload occurs once the pressure in the ventricle is greater than the blood pressure, thus, the aortic valve opens up.  
  • M eanwhile, the Preload is the volume of blood present in a ventricle, again usually the left ventricle of the heart, after passive filling and atrial contraction. Theoretically, it is the initial stretching of cardiac myocytes prior to contraction. Preload is affected by venous blood pressure and the rate of venous return are also affected by venous tone and volume of circulating blood.
  • Hypertension will increase the afterload since the ventricle will have to work harder to be able to eject the blood in the aorta since, as mentioned, the aortic valve will not open until the pressure in the ventricle is higher than the now elevated blood pressure. 
  • Other cardiac problems can increase afterload. Aortic stenosis will increases the afterload because the left ventricle has to overcome the pressure caused by the stenotic aortic valve in addition to the blood pressure in order to eject blood into the aorta. For instance, if the blood pressure is 120/80, and the aortic valve stenosis creates a trans-valvular gradient of 30 mmHg, the left ventricle has to generate a pressure of 150 mmHg in order to open the aortic valve and eject blood into the aorta.
  • In addition, Aortic insufficiency increases afterload because a percentage of the blood that is ejected forward regurgitates back through the diseased aortic valve. This leads to elevated systolic blood pressure.
  • Meanwhile, Mitral regurgitation decreases the afterload. During ventricular systole, the blood can regurgitate through the diseased mitral valve as well as be ejected through the aortic valve. This means that the left ventricle has to work less to eject blood, causing a decreased afterload.
  •   Normal cardiac output is about 4 -6 Liters/minute and is affected by body size, metabolic rate, posture, age, body temperature, anxiety, and other environmental factors.

TOPICS

Ablation

·         Destroying the plaque with laser.

 

Allen Test

·         The hand should blanch upon compression of the radial and ulnar arteries.  When the pressure on the radial artery is released, the hand should turn pink, thus, indicating patency.

 

 

Angina

  • Chest pain that may radiate down to the arm, usually the left arm. It is a sign of ischemia.
  • May be associated with stress or any type of anxiety and therefore is often relieved with rest or with use of Nitroglycerine.
  • Risk factores are those who smoke, obese, have diabetes mellitus, undergo a lot of stree, have Hypertension, and those with high cholesterol.
  • Men than premenopausal women and Afro Americans than whties are more prone. Increasing age and families with history of heart problems are contributing factos, alont with those who smoke, have HTN, obeses, undergo a lot of stress, lack of physical activity, diabetes mellitus, and elevated cholesterol.
  • While being treated for angina, person may under go angioplasty, may be on IV heparin derip to prevent thrombus formation, or even undergo Coronary artery bypass graft surgery (CABG) to increase blood flow to the heart muscle by way of using usually the Sapehnous vein for graft.
  • After the attack, person may be placed on anti-platelet aggregation (i.e. aspirin) or antiangina (i.e. Isordil, Nitroglycerine)

 

Angioplasty

·         A catheter with a balloon tip will compress the fatty lesions against the vessel wall.

 

Aortic Aneurysm

·         Feels a heart beat in the umbilical area

·         If it ruptures, can cause a decrease in sensation in lower extremities and decrease in urine output.

 

 

Arrhythmias (see ECG topic below for different Arrhythmias)

  1.     Atrial Arrhythmias – Atropine is the medication of choice.

2.    Ventricular Arrhythmias – Lidocaine and Procainamide are the medications of choice.

     3.    SVT supraventricular tachycardia (has chest pain and dizziness) - form a vagal or valsalva maneuver to reverse SVT. Other possible vagal maneuvers include ice to face holding breath and then bearing down,massaging the carotid artery on only one side of the neck, if vagal maneuvers don’t work, IV Adenosine (Adenocard) and antidysryhthmic agent is given

 

Artherectomy

·         Removal of the plaque via rotational and directional catheters.

 

 

Automated Internal Cardiac Defribillator (AICD)   (see Pacemaker)

·         Should not have a MRI done since it can cause dysrhythmias.

·         Patient should check and record pulse rate.

·         A patient can use the microwave.

 

Cardiac Catherization

·         Involves inserting the catheter into the cardiac chambers and blood vessels. Involves Angiography where the vessels are examined by injecting a contrast medium.

·         NPO the night before. Patient may feel a burning sensation or feel hot with the dye injection. But fluids are encouraged after the procedure to help flush out the dye.

·         Patient may be asked to cough and breathe deeply during procedure.

·         Should be on bed rest for 8-12 hours with pressure dressing applied over catheter site.

·         Peripheral site checked ever 15 minutes for 1 hr, then every 20 min for 2 hours, then every 4 hours. Palpate pulses distal to the catheter insertion (i.e. Check for pedal pulse if catherization was done through the femoral  area). Notify physician if peripheral pulse is lost or if pain, tingling or coolness occurs.

·         Checks for fluid overload. Symptoms are rales and tachycardia

·         Look for any bleeding from the puncture site. Risk for hematoma formation, thus, check vital signs and temperature of leg.  

·         Though voiding is checked later, it is not the immediate concern since the dye used has a diurectic effect. Yet, urine production should not be less than 30 ml/hr.

·         After discharge, patient should avoid any heavy lifting or bending.

 

 

Cardiac Enzymes / Proteins

·         Enzymes / Proteins that get elevated when there is cardiac damage, most commonly due to myocardial infarction (MI).

·         Note that these enzymes may arise also during a cardiopulmonary resuscitation or cardiac surgery. Below are some commonly checked enzymes/ protein.

         1. Troponin

o        A commonly used diagnositc test since this protein rises rapidly and stays elevated for about 8 days.

         2. CPK-MB

o        Rises rapidly like Troponin but it may also rise during muscle injury.

o        Exercise can make this enzyme rise.

       3. Myoglobin

o        An enzyme that is specific to cardiac muscle but tends to return to normal rapidly.

       4.LDH - Lactic deyhyrdogenase

o      An enzyme that is slow to rise during a cardiac injury.

o        Can be used to detect MIs greater than 24 hours old.

 

 

Cardiac Tamponade 

·         Blood or fluid filling up the pericardial space thus causing increasing pressure on the heart.

·         Can lead to pulsus paradoxus (at least a 10mmHg of drop in blood pressure) during inspiration.

 

Central Line

·         Should be covered with an occlusive but transparent dressing.

·         Removed by asking patient to do the Valsalva menuever

·         At insertion, patient should be on Trendelenburg position to engorge the vessels and make insertion easier and lessen the possibility of air entering.

·         Air embolism can occur at insertion or removal. Development of dyspnea with substernal chest pain with fear and confusion would suggest air embolism.

 

Congestive Heart Failure (CHF)

·         Patient developing crackles with distended veins are signs of CHF.

·         Nurse can anticipate an order of a diuretic to get rid of excess fluid.

 

Cor Pulmonale, also referred to as Right-Sided Heart Failure

·         Results in the edema of legs and feet, distended neck veins, enlarged liver. Patient may have increased urination at night.

 

Coronary Artery Bypass Graft (CABG)

·         Pallor and coolness of skin immediately after CABG is normal.

·         Any chest drainage greater than 100ml is too much.

 

 

Cardiopumonary Resuscitation (CPR) 

 

1. CALL

Check the victim for unresponsiveness. If there is no response, Call 911 and return to the victim.

2. BLOW

Tilt the head back and listen for breathing.  If not breathing normally, pinch nose and cover the mouth with yours and blow until you see the chest rise. Give 2 breaths.  Each breath should take 1 second.

3. PUMP

If the victim is still not breathing normally, coughing or moving, begin chest compressions.  Push down on the chest 11/2 to 2 inches 30 times right between the nipples.  Pump at the rate of 100/minute, faster than once per second.

 

CVP

·         Normal reading is between 3-8cm of H20. Greater than 8 means volume excess.

·         Sterile technique not clean technique should be used in changing dressing.

·         Patient should be supine and with head no more than 45 degrees of elevation.

·         The zero on the manometer should be on fourth – fifth intercostals space midaxillary line.

            How to read a CVP

o        Patient must be in supine position.

o        Turn the stop-cock to off position form the IV fluid to the patient.

o        Look at the top of the meniscus.

 

 

Deep Vein Thrombosis (DVT)

·         Think of the veins as a hose and the water that flows in it as the blood. When the hose is kinked, water flow is interrupted. The hose can also develop certain impurities that interrupt the water flow. So, DVT occurs when a clot (thrombus) forms, usually in deep veins on the legs, thus, blood flow is slowed down. Flow of blood is further slowed down if patient is stationary – sitting or standing for long periods.

·         Normally, body can break down these clots but when there is blood stasis coupled with injury to vessel wall and hypercoagulability (these three known as Virchow’s triad), thrombus will form.

·         Homan’s sign (pain at dorsiflexion of foot) is NOT a reliable sign. Unilateral edema (best determined by measuring the circumferences of the legs from thigh to ankle) of the affected side, along with pain, increase in temperature of the affected side, are good signs of DVT.

·         A thrombus that breaks away and travels to the lung leads to Pulmonary Embolism (PE), which is life threatening. Patient with PE will exhibit dyspnea, tachypnea, chest pain, cough that may have blood.

·         Should be on 5 - 7 days of rest. Patient is usually on anticoagulant such as heparin, a low molecular weight heparin (ie Lovenox) or and warfarin (Coumadin).

·         Patient on anticoagulant should be monitored for signs of bleeding (ie. form nose, gums, easy bruising).  A patient with excessive bleeding due excess in heparin dosage should be given Protamine Sulfate.

·         Advice patient on Coumadin to avoid foods high in Vitamin K (avocados, cabbage, broccoli and green leafy vegetables).

·         Patient may be on Antithrombolytic stockings which are best worn during the day before getting up from bed since the legs are not as edematous than in the evening or even after a warm bath. If ordered to be placed at night or afternoon, ask the patient to go back to bed and rest the legs for at least 30 minutes so stocking would be easier to put on.

·         If not the stockings, patient maybe be asked to use an intermittent pneumatic compression device that has an elastic compression or wrap device attached to an air hose that is connected to an electric controller, which controls the amount of compression. Nurse should watch for any skin irritation on the patient that the stockings or wraps may cause. 

·         If patient is high risk for PE or anticoagulant therapy is contraindicated, patient may undergo surgery where a catheter directly delivers the thrombolytic agent to dissolve the clot and the a IVC filter (inferior vena cava) is placed usually by the groin area below the renal veins to help trap the clots that might travel from the leg to the lungs or brain.  

 

 

Defibrillation

  • To differentiat from Cardioversion, Defribrillation ia an emergency procedure to treat ventricular fibrillation while Cardioversion is elective procedure.for any dysrhythimias. Thus, informed consent is needed for Cardioversion.
  • In an emergency situation, CPR is usually being performed before defribillation in order to manually pump blood out of the heart.
  • When turning the defribillator on, leads are attached to the patient and a gel is applied to the paddles. The paddles are placed on the right sternalborder and over the apex of the heart. (Note: Portable defribillator will also indicate the same positioning of the manual pads) An electric charge is selected usually around 200 joules in the first attempt and the person holding the paddles will call out "All Clear." Joules increases usually during the next attempts.
  • During Cardioverions, a low voltage, around 25 - 360 joules is chosen.
  • After charging the paddles, check the monitor between shocks to see if the SA node has been re-established.
  • During defibribillation, Epinephrine may be adminstered IV push Q 3 - 5 minutes and Sodium Bicarbonate for metabolic acidosis; to promote drug excretion in overdosage.

Echocardiogram

·         A diagnostic tool used to identify the structural changes of the heart.

·         Can either be two dimensional or a trasnesophageal echocardiogram (TEE), where the flexible tube is inserted orally to get a better view.

·         In the event of an MI, it can detect dysfunctional movement in the muscle of the heart.

 

 

Electrocardiogram (ECG)

  • Commmonly used noninvasive diagnostic test for those with cardiac disease. See common ECG strip below

As seen on the diagram an ECG strip below, 1 small square represents 0.04 seconds and one large square 0.20 seconds. Thus, one large square equals 5 small squares. The vertical line is the amplitude or the voltage and the horizontal line represents time.

 

 

 

 

                        I. Two options to get the rhythm

                        A. 30 large squares in EKG  is 6 seconds; multiply the number of QRS complex found in 30 large squares by 10

                        B. Quick rule of 300 – Count the Big squares between “R’s”. Divide 300 by the number of big squares

 

                        II. Some Electrolyte Imbalances on EKG

                                    Hyper MG - prolonged PR , widened QRS and elevated T

                                    Hyper K - prolonged PR, , widened QRS , tented T;  depressed ST segment -- if really high as in >9, may have sine waves; prolonged QT ;

leads to diarrhea and abdominal cramping

                                    Hypo K – presence of a clear U wave 

                                    Hypo M (<1.5) - widened QRS, prolonged QT; 

                                                Patient will present a positive Troussseau and Chvostek signs, be tacchycardic, and be hypotensive

 

 

 

I.          RHYTHMS WHERE IMPULSE IS NORMALLY GENERATED BY THE SINUS NODE.

 

Normal Sinus Rhythm
In
a normal heart rhythm, as mentioned above under the normal heart conduction section, the electrical impulse is normally generated by the sinus node (SA) and travels in the heart in a normal fashion. Normal adult heart rate is about 60-100 beats per minute while a newborn can have a heart rate up to 160 beats per minute.


                                    Rate                 =          60 -100

                                    Rhythm            =          Regular

                                    P waves           =          uniform (one precedes the QRS)

                                    PR                    =          0.12 – 0.20

                                    QRS                 =          less than 0.12 seconds.

            NOTE: Normal sinus is treated if there is PEA, Pulseless Electrical Activity.  

                                   


Sinus Tacchycardia
Same as normal sinus except for the rate. Sinus tachycardia means the heart rate has a regular rhythm but the impulse is being generated at a fast pace than the normal heart rhythm. Sinus tachycardia can be seen normally with those engaged in exercise or when one is excited. It can be seen of the person has a fever, stress, anxiety, decreased oxygenation, and can be caused by certain medications, legitimate or not (cocaine for instance).
                                  


                                    Rate                 =          > 100

                                    Rhythm            =          Regular

                                    P waves           =          uniform (one precedes the QRS)

                                    PR                    =          0.12 – 0.20

                                    QRS                 =          less than 0.12 seconds.



Sinus Bradycardia
Same as normal sinus except that for the rate. It can be caused by vagal stimulation, vomiting, or even going to the bathroom or some drugs (ie too much digoxin or anaesthesia)
 



                                   

                                    Rate                 =          < 60    

                                    Rhythm            =          Regular

                                    P waves           =          uniform (one precedes the QRS)

                                    PR                    =          0.12 – 0.20

                                    QRS                 =          less than 0.12 seconds.

 

Sinus Arrhythmia 
Almost similar to a normal sinus except that the rhythm is Irregular. It somehow correlates with the patients breathing; it increases with the patient’s inspiration and decreases with expiration.           

                                    Rate                 =          60 -100

                                    Rhythm            =          Irregular

                                    P waves           =          uniform (one precedes the QRS)

                                    PR                    =          0.12 – 0.20

                                    QRS                 =          less than 0.12 seconds.

 

 

II.        RHYTHMS WHERE IMPULSE IS OUTSIDE THE SINUS NODE.

            Atrial rhythms – arise outside the SA node but above the ventricles. The P wave can be flat, notched, saw tooth or peaked.

Wandering Atrial Pacemaker (WAP) 
P waves can be flat, notched, saw tooth, or peaked



                              

                                    Rate             =          60 - 100                                
                                    Rhythm        =          Irregular.

                                    P waves       =          Varies but also precedes QRS

                                    PR               =          Normal .

                                    QRS             =          Normal .

 

Premature Atrial Contraction (PAC) 
The atria fires an early impulse which causes the heart to beat earlier causing irregularity in the heart rhythm. In essence, there is an irritable focus in the atrium causing it to fire prematurely and produces an ectopic beat. The conduction through the ventricles is normal. It can be caused by stress, digitalis toxicity, low potassium or Magnesium, or an MI.

PAC is usually a precursor for Atrial Tacchycardia. It can be seen as a single occurrence, a multiple occurrence or a pattern.

                                    A. Atrial Bigeminyoccurs every other beat. Means it is a pattern; something that happens every other beat.

                                    B. Atrial Trigeminyoccurs every 3 beats.

                     

                                    Rate            =          Depends on the underlying rhythm.

                                    Rhythm       =          Irregular. One can have a normal sinus with a PAC

                                    P waves      =          Has a different morphology (shape) than the rest of the strip.

                                    PR              =          0.12 – 0.20 It can be prolonged.

                                    QRS           =          less than 0,12 seconds. May be followed by a pause.

 

Atrial Tacchycardia (also referred to as Supraventricular Tacchycardia) 
There is a single irritable site within the atria causing it to fire repetitively at a very rapid rate. In this abnormal heart rhythm the impulse stimulating the heart is not generated by the sinus node, but instead comes from a collection of tissue around and involving the atrioventricular (AV) node.  These electrical impulses from this abnormal site are generated at a rapid impulse, which may reach 250 beats per minute.



                                    Rate                 =          160 - 250

                                    Rhythm            =          Regular

                                    P waves           =          one precedes the QRS (it may be hard to see)

                                    PR                    =          0.12 – 0.20

                                    QRS                 =          less than 0.12 seconds.

 

Atrial Fibrillation  
The atria is irritable and there is a multitude of foci in the atria firing electrical impulses. This causes the atria to depolarize repeatedly in a fibrillating manner. The AV node blocks most of the impulses allowing only a number of impulse to go through to the ventricles.


FIGURE A

FIGURE B

                                    Rate                 =          >350  ;             Ventricular       =          <100, means controlled;  >100, means rapid ventricular response.

                                    Rhythm            =          Irregular

                                    P waves           =          Not seen. One sees fibrillating waves.

                                    PR                    =          Can not be measured.

                                    QRS                 =          less than 0.12 seconds. Normal .

 

Atrial Flutter  
There is a single irritable focus in the atria that creates an impulse that is conducted in a rapid, repetitive fashion. In this abnormal heart rhythm, the AV node is not involved and the heart rate would be faster than that in supraventricular tachycardia.


                                    Rate                 =          250 - 350

                                    Rhythm            =          Regular or irregular

                                    P waves           =          Saw tooth like

                                    PR                    =          Can not be measured

                                    QRS                 =          less than 0.12 seconds.

 

 

 

III.       JUNCTIONAL RHYTHMS

  AV Junctional Rhythm  
This is not a rhythm. It is an event where the rate depends on the underlying rhythm


                                    Rate                 =          Depends on underlying rhythm

                                    Rhythm            =          Irregular

                                    P waves           =          Can be before, after or within the QRS. If visible it is inverted. If the strip shows one P and it is inverted, then it is a PJC not PAC.

                                    PR                    =          < 0.12 seconds if P wave precedes the QRS, otherwise there is no PR interval

                                    QRS                 =          less than 0.12 seconds.

            Note:    PAC may have an inverted P but the PR in the PAC is not short.

                        PACs are more common than PJC

 
Junctional
Escape


                                    Rate                 =          40 – 60

                                    Rhythm            =          Regular

                                    P waves           =          Can be before, after or within the QRS.

                                    PR                    =          < 0.12 seconds if P wave precedes the QRS, otherwise there is no PR interval

                                    QRS                 =          less than 0.12 seconds.

 

Accelerated Junctional Rhythm


                                    Rate                 =          60 – 100

                                    Rhythm            =          Regular

                                    P waves           =          Can be before, after or within the QRS.

                                    PR                    =          < 0.12 seconds if P wave precedes the QRS, otherwise there is no PR interval

                                    QRS                 =          less than 0.12 seconds.

 
Junctional Tacchycardia


                                    Rate                 =          100 – 180

                                    Rhythm            =          Regular

                                    P waves           =          Can be before, after or within the QRS.

                                    PR                    =          < 0.12 seconds if P wave precedes the QRS, otherwise there is no PR interval

                                    QRS                 =          less than 0.12 seconds.

 

IV.       AV BLOCKS

First Degree Block   
The AV node holds each impulse longer than normal before conduction it through the ventricles. Each impulse is conducted and proceeds normally. In essence, electricity is held at the AV node longer before it gets through, thus, there is a wider PR interval.


 

                                    Rate                 =          Depends on underlying rhythm

                                    Rhythm            =          Regular or Irregular

                                    P waves           =          Upright and uniform each before QRS. 

                                    PR                    =          > 0.20 (greater than 5 boxes) and it is constant throughout.

                                    QRS                 =          less than 0.12 seconds.

 

Second Degree Block or Type I or Wenckebach
The AV node initiates the impulse but each is delayed in the AV node longer than the preceding one until one is completely blocked


                                    Rate                 =          Slower than normal since some beats are not conducted.

                                    Rhythm            =          Irregular

                                    P waves           =          Upright and uniform some NOT followed by QRS. 

                                    PR                    =          Progressive. Progressively longer until one P wave is not followed by a QRS. Then the cycle repeats.

                                    QRS                 =          less than 0.12 seconds.

 

Second Degree Block or Type II    
The AV node selectively conducts some beats while blocking others. Those not blocked proceed normally through the ventricles although they may delay slightly in the node so that more P waves are created.



 

                                    Rate                 =          Usually bradycardia

                                    Rhythm            =          Regular or Irregular

                                    P waves           =          Always more than QRS. There are 2 -3 or more P waves before each QRS 

                                    PR                    =          Those conducted may be > 0.20 (greater than 5 boxes)

                                    QRS                 =          less than 0.12 seconds.


Third Degree Block   
The block at the AV node is complete. Sinus beats are not conducted.


       


Rate                 =          Usually bradycardia

                                    Rhythm            =          P à P is regular and R à R is regular

                                    P waves           =          More P waves than QRS. P waves are unrelated to the QRS complex.  

                                    PR                   =         

                                    QRS                =          Either > or <  0.12 seconds.

 

V.        VENTRICULAR RATES

Premature Ventricular Contraction (PVC).  
One ought to take note of the number of PVCs, the frequency, types and patters.

Ccan be:          a. Unifocal – same configuration and from the same focus.

                        b. Multifocal – from different foci and varied configurations.

                        c. Run of PVCs – 3 or more

                        d. R on T phenomenon – a PVC that occurs on the downslope of the T wave

                        e. PVC couplet – 2 consecutive


                       

                                    Rate                 =          Determined by the underlying rhythm. The PVCs are not included in the rate since they DO NOT produce a pulse.

                                    Rhythm            =          Regular or Irregular

                                    P waves           =          Ectopic

                                    PR                    =          None

                                    QRS                 =          > 0.12,  bizarre and wide

 

Idioventricular Rhythm (also referred to as the Agonal or Dying Heart)


                                    Rate                 =          20 – 40 but can be less. If . 40, it is an Accelerated Idioventricular.

                                    Rhythm            =          Usually Regular

                                    P waves           =          None

                                    PR                    =          None

                                    QRS                 =          Wide and bizzare

 

Ventricular Tacchycardia 
This is a dangerous type of rapid heart rhythm because it is usually associated with poor cardiac output (amount of blood ejected out of the heart). There are two types:

                                    a.         Stable – ventricles still contract and the patient has a pulse from enough cardiac output

                                    b.         Unstable – No pulse and can progress to V-fib

                                   

                                    Rate                 =          150 – 250, if >250 = Ventricular Flutter

                                    Rhythm            =          Regular

                                    P waves           =          uniform (one precedes the QRS)

                                    PR                    =          0.12 – 0.20

                                    QRS                 =          less than 0,12 seconds.

 

Ventricular Fibrillation





                                   Rate                 =          Can’t be determined
                                   Rhythm            =          Chaotic baseline. Can’t be determined.

                                   P waves           =          None

                                   PR                   =          None

                                   QRS                 =          None

  

Ventricular Standstill  
Only P waves are present. CR is started and Atropine is usually given.


  

 

 

 

 

 

Embolism

·         An emboli interferes with adequate circulation.

·         CONFUSION is the first symptom.  So, instruct patient to remain in bed and take an ABG.

·         Common with fractures of long bones.

Types:

          a.     AIR EMBOLISM - put patient in left position and lower head, then give oxygen,

      b.     FAT EMBOLISM – occurs often with those with fractures on long bones or pelvic bones.

 

 

Heart Failure

  • Heart's inability to pump enough blood to supply the various body organs.
  • Can be due to so many reasons, some of which are:
      1. Arteriosclerosis - vessels become narrow thus increasing peripherial resistance and leads to hypertension
      2. Valvular heart disease - due to either incomplete closure of valves or narrowing of the valves
      3. Rheumatic heart disease - an infecdtion that damages the heart valves
      4. Ischemic heart - sclerosed coronary arteries
      5. Pulmonary disease - damage to arterioles of lungs causes vascular constriction that increase workload of heart.

Heart Failure - Left and Right Side

    • Left Sided Heart Failure
      • Remember that the left heart is pumping the blood throughout the body
      • Dyspnes upon exertion
      • Leads to pulmonary edema - crackles can be heard
      • Cough can have frothy bloody tinged sputum
    • Right Sided Heart Failure (also referred to as Cor Pulmonale)\
      • Remember that the right side receives the blood from various parts of the body.
      • Ankle and lower extremities may be edematous since blood is not flowing towards the heart.
      • Coolness of extremities
      • Can led to liver enlargement.
  • So, it is important to keep the efficiency of the hearts ability to pump. Thus, cardiac glycosides may be given. Note: Digitalis, which increases the heart pumping ability had a loadingt dose (about 0.5 - 1mg) and maintenance dose (about 0.0125 - 0.5 mg)
  • Diuretics may be given to help reduce edema
  • Encourage person to restrict sodium. So, patient is on a low sodium diet.

 

 

Heart Sounds

·         Remember the phrase All Patients Take Meds during auscultation. A is or Aortic area (right of sternum, 2nd intercostal space),  P is for Pulmonic (left of sternum, 2nd  intercostal space), T is for Tricuspid (left of sternum, 4th  inercostal space), and M is Mitral (the apex of the heart, left of sternum, midaxillary line, 5th  intercostal space).

 

 

 

Hypertension (HTN)

  • Persistent elevaton of systolic blood pressure over 140mmHg and a distolic pressure of over 90mmHg.
  • May have no symptoms. But the common ones are headaches, dizziness, polyuria, and may have angina.
  • Many individuals do not have a major known cause and develop HTN gradually but the ceratin contributing factors are family history, too much sodium intake, lack of physical activity, high cholesterol, and excessive alcohol

 

 

Hypovolemia

·         Occurs when the circulating blood voulume is low and must be replaced with blood if the patient is actively bleeding whose hemolgobin may range from 7- 8 g/d; Crystalloids such as normal saline or olactated Ringer - used when the volum depletion does not have to be corrected rapidly. Crystalloid do not cause allergic reactions and is inexpensive; Colloids such as albumin - used for rapid volume is necessary but that there is no need to use blood.

·         Hematocrit, Bun and specific gravity values will be high or elevated.

·         Will res

 

 

 

Inferior Vena Cava (IVC) filter (see DVT)

·         A mesh like device that is placed usually below the inferior vena cava and the lowest renal veins in order to tap clots that tend to break away from a leg DVT and moves towards that lungs or brain.

 

Inotropic

·         Synonymous to cardiac contractility. Anything that increases the strength of cardiac contractility (ie. inotropic drugs such as digoxin, dobutamine or dopamine)

·         Basically increases the myocardial oxygen consumption at the time when the heart is starved for oxygen.

 

Left Sided Failure

·         Will result in the SOB, hypoxia, and fatigue at exertion: the same symptoms for Pulmonary edema

·         Patient may experience day time oliguria and develop crackles in the lungs.

·         Neck distention may occur.

        NOTE EDEMA is best measured not by pitting but by measuring the edematous area.

 

 

Mean Arterial Pressure

·         It is the amount of pressure necessary to provide enough perfusion to the arteries, brain and kidneys. Yet, it is often referred to as the difference between the systolic and diastolic pressure. Although will not possibly asked in NCLEX, MAP is mathematically calculated as (2 x diastolic) / 3.  

·         Normal MAP range is 70 – 100. Defined as the difference between the systolic and diastolic pressures.

·         MAP is affected by the cardiac output (CO), systemic vascular resistance (SVR) and central venous pressure (CVP). It is based on the relationship of flow, pressure and resistance. CVP is small enough that it is neglected. Thus, MAP can be approximated as CO x SVR and a change in either variable affects the MAP.  

 

 

Myocardial Infarction (MI) - Heart Attack

  • In essence, a heart attack is an occlusion of the coronary artery, hence, there is a decrease of blood and oxygen supply to the heart muscle.
  • Chest pain in a heart attack is severe and crushing and UNRELIEVED by rest nor by NITROGLYCERIN. Often is it radiating to on or both arms, jaw, neck and/or back. NOTE: Angina is a chest pain often relieved by Nitroglycerin.
  • Person may expreience nausea, vomiting, indigestion, dyspnea. Note: Indigestion is somewhat described when a patient says, "That food does not seem to be agreeing with me."
  • I/O must be monitored. Too much fluid can cause the heart to work harder and precipitate CHF and too liitle may cause deyhydration. Also, too much urine output may indicate inadequate renal perfusion and too little output may mean dehydration.
  • IV access is important to place on a patinet for any emergency IV drugs.
  • Beta-blockers may be given to a patient along with morphine sulfate for pain and to reduce the preload and afterload pressures. Dysrhythmia medications (i.e. lidocaine, verapamil) may be adminstered and also anticoagulants.
  • A person who has an MI may have dysrhythmias complications later on.
  • After an MI - resume sexual activity only if patient can walk flight of stairs or walk a block without SOB or chest pain
  • Markers of MI are Myoglobin, Creatine kinase-MB (CK-MB), Troponin-I, all present within 4-8, 8-24 and 72hrs, respectively, after an MI  Note: Myoglobin is produced both by skeletal and cardiac muscles, and therefore also present after a person exercises or if a person suffers burn. 
  • Doctors may use more than one test to determine if a person who has chest pain is having a heart attack. Troponin protein is generally considered the most accurate test, and CK-MB is also highly accurate in detecting damage to the heart, even when there is no other evidence of a heart attack. Myoglobin and Creatine kinase almost always rise in patients with a heart attack, but they are less specific; other conditions can also produce an increase in these two tests.
  • Depressed ST segment is an indication of MI.
  • Advise patient to stop smoking, decrease caffeine intake, modify sodium and fat intake and to have a regular moderate physical activity.  

NOTE: Probably will not be asked in NCLEX but its good to know that persons whose kidneys have failed can also have high CK–MB levels without having had a heart attack. Rarely, chronic muscle disease, low thyroid hormone levels, and alcohol abuse can increase CK–MB, producing changes similar to those seen in a heart attack.

 

Occlusions

  1.     Arterial occlusion

·              Can result in gangrenous area.

·              Usually occurs on the toes, foot and malleolus areas.

·              Skin temperature is COOL. Skin is thin and painful with more defined margins than venous ulcers.

·              Wound is usually without drainage.

    2.     Venous occlusion

·              Edema in the affected extremity, usually around lower calf and ankle area, the area covered by sock.

·              Skin is dry and scaly.

·              Wound margin is irregular and usually with exudate.

 

Pacemaker (see AICD)

  • The main purpose of the pacemaker is to initiate the heart beat if the SA node can't do the what it's suppose to do, to initiate the "firing" impulse.

    Types

    • On demand - functions when the heart rate goes below a set rate
    • Fixed rate - a constant rate is set to stimulate the ventricle
    • Temporary - Used in ermergency situation like for MI patients with heart blocks or those who has had cardiac arrest
    • Permanent - the generator is implanted under the skin usually below the clavicle
  • Person should avoid any situation involving electomagnetic fields such as the security scanners at the airport. Person should be hard scanned at the ariport.
  • Individual should not have an MRI since it can cause dysrhythmia but person should be able to use a microwave.
  • Patient should check and record pulse rate. .

 

Procedures

·         Artherectomyremovied of plaque via rotational and directional catheters

·         Angioplasty – a catheter with a balloon tip will compress the fatty lesions against the vessel wall.

·         Ablation – destroying the plaque with laser

 

Pulse pressure

·         Increase in pulse pressure is an indication of ICP

 

Pulsus Paradoxus

·         A drop in blood pressure of at least 10mmHg.

·         Basically indicates a decrease in blood pressure during inspiration because of the increase in blood enterring the atrium during inspiration.

 

 

Shock

  • Simply stated, shock occurs when the blood supply to the tissues is inadequate to meet the requirements of the body. In an attempt to compensate, the body will try to increase the heart to improve the pumping of blood to vital organs. Also, the body will constrict blood vessels, which lead to a thready pulse. Eventually when the shock is not corrected, the heart rate will slow down and there won’t be enough blood to be pumped leading to low blood pressure. Since blood supply to the lung is also affected, eventually breathing becomes labored (elevated respiration).
  • So if in shock, elevate legs to improve circulation to brain and vital organs without increasing workload.
  • Tachycardia and hypotension are indicative of shock, especially if patient has been in an auto accident.

 

 Types of Shock:

  1.     Hypovolemic Shock (Fluid volume deficit)

·              Often caused by blood loss due to surgery or trauma (i.e. burns resulting in fluid loss, expriencing vomiting and diarrhea)

  2.     Cardiogenic Shock

·              Caused by inability of the heart to pump blood to the body and this is often precipitated by myocardial infarction, a blockage on one of the arteries that supply the heart muscle.

  3.     Anaphylactic Shock

·              Caused by an allergic reaction to an allergen.

  4.     Septic Shock

·              Caused by an infection that releases toxins into the system. 

·              Same effect as anaphylactic shock but more gradual.

 

  • Think that one would like to restore enough perfusion to the organs by restoring the heart's ability to pump blood. If shock is due to infection, one may have to adminster antibiotic, and immediately do blood, urine, and possibly sputum cultures and test for any sensitivity to any antibiotics
  • Systolic blood pressure should be greater than 90mmHg and certian medications to improve myocardial contractions (i.e. digitalis, atropine) may be given.
  • Adequte urin output of about 30ml/hr should be maintained and medications (i.e. Mannitol, lasix) may be ordered to maintain adequate output.

Vasodilator

·         Anything thtat causes more blood to remain in the peripheral vessels causing less blood to be returned to the heart. In essesnce, having a cholinergic effect.

·         In effect, vasodilators reduces preload. Examples of vasodilators are Diuretics, Nitroglycerin and calcium channel blocker such as Diltiazem and Procardia.

 

Vasopressors

·         Will res

·         Will res

 

 

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