Cardiovascular 1 & 2 Flashcards
In adults, what is the rate that the electrical impulses of the heart occur?
60-100 times per minute.
What is the process where the electrical impulses travel from the SA node through the atria to the atrioventricular AV node called?
Conduction.
What happens to the impulse at the AV node?
The AV node slows the impulse from the SA node, giving the atria time to contract and fill the ventricles with blood.
What is electrical relaxation called?
Repolarization
What is the electrical stimulation called?
Depolarization.
What is the mechanical contraction called?
Systole
What is the mechanical relaxation called?
Diastole.
What is the heart rate influenced by?
The autonomic nervous system which consists of sympathetic and parasympathetic fibers.
What are the sympathetic nerve fibers attached to the heart and arteries also called?
Adrenergic fibers.
What does stimulation of the sympathetic system result in?
Positive Chronotropy - Increased HR
Positive Dromoptropy - Increased AV conduction
Positive Inotropy - Increased force of myocardial contraction.
Constriction of peripheral blood vessels which leads to increased BP.
What effect does Parasympathetic stimulation have on the heart & arteries?
Negative chronotropy - reduced HR
Negative Dromoptropy - reduced AV conduction
Reduced force of myocardial contraction.
Dilation of arteries which leads to lowered BP.
What negative effect may happen with increased sympathetic stimulation?
Sympathetic stimulation caused by exercise, anxiety, fear, fever, administration of catecholamines such as dopamine, aminophylline or dobutamine may increase incidence of arrythmias.
What positive effect may happen with decreased sympathetic stimulation?
decreased sympathetic stimulation caused by rest, anxiety reduction methods such as therapeutic communication or medication or administration of Beta blockers may decrease incidences of arrythmias.
Why should we not clean a patients skin with alcohol prior to placing ECG nodes?
Cleansing the skin with alcohol removes any oily residue from the skin, it also increases the skin’s electrical impedance and hinders detection of the cardiac electrical signal.
how many leads are used on a standard ECG, and where are they placed?
12 leads.
6 on chest and 4 on the limbs.
The limb electrodes are placed on areas that are not bony and that do not have significant movement.
On the ECG strip, what is measured on the horizontal axis?
Time and rate.
On the ECG strip, what is measured on the vertical axis?
Amplitude and voltage.
What is the name of the wave that represent the electrical impulse stating in the SA node and spread through the atria?
The P wave. The P wave represent atrial depolarization.
What is the normal height and duration of the P wave?
Normally 2.5 mm or less in height and 0.11 seconds or less in duration.
What is the name of the wave that represent ventricular depolarization?
QRS complex.
The Q wave is the first negative deflection after the P wave.
The R wave is the first positive deflection after the P wave
The S wave is the first negative deflection after the R wave.
What is the normal duration of the QRS complex?
Less than 0.12 seconds in duration.
Which wave represent ventricular repolarization?
The T wave.
Why can we not see atrial repolarization on the ECG?
It occurs at the same time as ventricular depolarization which is blocking its view on the ECG strip.
What wave represent repolarization of the Purkinje fibers?
The U wave.
The U wave is rare, when are we most likely to see it?
It sometimes appears in patients with hypokalemia, hypertension or heart disease. If present it follows the T wave.
What generates the sinus rhythm?
The electrical conduct that begins in the SA node.
What 6 characteristics does a normal sinus rhythm have?
Ventricular and atrial rate: 60 to 100 bpm in the adult
Ventricular and atrial rhythm: Regular
QRS shape and duration: Usually normal, but may be regularly abnormal
P wave: Normal and consistent shape; always in front of the QRS
PR interval: Consistent interval between 0.12 and 0.20 seconds
P:QRS ratio: 1:1
What 3 types of Sinus node arrythmias are there, where do they originate from?
Sinus Bradycardia
sinus tachycardia
Sinus arrythmia
All originate in the SA node.
When does sinus bradycardia occur?
When the SA node create impulses at a slower than normal rate.
What are some causes of sinus bradycardia?
lower metabolic needs (e.g., sleep, athletic training, hypothyroidism), vagal stimulation (e.g., from vomiting, suctioning, severe pain), medications (e.g., calcium channel blockers [e.g., nifedipine, amiodarone], beta-blockers [e.g., metoprolol]), idiopathic sinus node dysfunction, increased intracranial pressure, and coronary artery disease, especially myocardial infarction (MI) of the inferior wall.
What’s normally the cause for unstable and symptomatic badrycardia?
Hypoxemia
What are the 6 most common characteristics of Bradycardia?
Ventricular and atrial rate: Less than 60 bpm in the adult
Ventricular and atrial rhythm: Regular
QRS shape and duration: Usually normal, but may be regularly abnormal
P wave: Normal and consistent shape; always in front of the QRS
PR interval: Consistent interval between 0.12 and 0.20 seconds
P:QRS ratio: 1:1
What separates bradycardia from normal sinus rhythm ?
The rate.
What is sick sinus syndrome?
SA node dysfunction.
Explain how we would treat Bradycardia?
Resolving causative agent.
If clinical symptoms occur such as alteration in metal status, chest discomfort or hypotension then we may give 0.5mg of atropine as IV bolus and repeat Q3-5 min until max does of 3mg.
If unresponsive to atropine we may give Dopamine, isoproterenol or epinephrine.
What is Sinus tachycardia?
When the sinus node create impulses faster than the normal rate.
What are some causes of Tachycardia?
Physiologic of psychological stress e.g acute blood loss, anemia, shock, hypervolemia, hypovolemia, HF, pain, hypermetabolic states, fever exercise, anxiety.
Medication that stimulate sympathetic response (catecholamines, aminophylline, atropine) Coffee, nicotine and illicit drugs such as amphetamine, cocaine, ecstasy.
Autonomic dysfunction resulting in postural orthostatic tachycardia syndrome (POST) - characterized by tachycardia without hypotension, palpitations, lightheadedness, weakness and blurred vision with sudden postural changes.
What are 6 common characteristics of tachycardia?
Ventricular and atrial rate: Greater than 100 bpm in the adult, but usually less than 120 bpm
Ventricular and atrial rhythm: Regular
QRS shape and duration: Usually normal, but may be regularly abnormal
P wave: Normal and consistent shape; always in front of the QRS, but may be buried in the preceding T wave
PR interval: Consistent interval between 0.12 and 0.20 seconds
P:QRS ratio: 1:1
What may happen as the heart rate is increasing with tachycardia?
The diastolic filling time decreases, possibly resulting in reduced cardiac output and subsequent symptoms of syncope (fainting) and low blood pressure. If the rapid rate persists and the heart cannot compensate for the decreased ventricular filling, the patient may develop acute pulmonary edema.
Waht are some ways we will try to manage tachycardia?
Vagal maneuvers such as carotid sinus massage, gagging, bearing down against a close glottis, forceful and sustained coughing, and applying a cold stimulus to the face.
Administration of adenosine.
Synchronized cardioversion
IV beta blockers or calcium blockers
Explain what Sinus Arrythmias are?
Sinus arrhythmia occurs when the sinus node creates an impulse at an irregular rhythm; the rate usually increases with inspiration and decreases with expiration.
What are 6 common characteristics of Sinus Arrythmias?
Ventricular and atrial rate: 60 to 100 bpm in the adult
Ventricular and atrial rhythm: Irregular
QRS shape and duration: Usually normal, but may be regularly abnormal
P wave: Normal and consistent shape; always in front of the
QRS PR interval: Consistent interval between 0.12 and 0.20 seconds P:QRS ratio: 1:1
How are Sinus Arrythmias usually treated?
Sinus arrhythmia does not cause any significant hemodynamic effect and therefore is not typically treated
Where does Atrial Arrythmias originate from?
Atrial arrhythmias originate from foci within the atria and not the SA node. These include aberrancies such as premature atrial complexes (PACs) as well as atrial fibrillation and atrial flutter.
What is a PAC?
A PAC is a single ECG complex that occurs when an electrical impulse starts in the atrium before the next normal impulse of the sinus node. The PAC may be caused by caffeine, alcohol, nicotine, stretched atrial myocardium (e.g., as in hypervolemia), anxiety, hypokalemia (low potassium level), hypermetabolic states (e.g., with pregnancy), or atrial ischemia, injury, or infarction.
Waht are the most common characteristics of a PAC?
Ventricular and atrial rate: Depends on the underlying rhythm (e.g., sinus tachycardia)
When are PACs often seen on the ECG?
With Sinus tachycardia.
Ventricular and atrial rhythm: Irregular due to early P waves, creating a PP interval that is shorter than the others. This is sometimes followed by a longer-than-normal PP interval, but one that is less than twice the normal PP interval. This type of interval is called a noncompensatory pause
QRS shape and duration: The QRS that follows the early P wave is usually normal, but it may be abnormal (aberrantly conducted PAC). It may even be absent (blocked PAC)
P wave: An early and different P wave may be seen or may be hidden in the T wave; other P waves in the strip are consistent
PR interval: The early P wave has a shorter-than-normal PR interval, but still between 0.12 and 0.20 seconds
P:QRS ratio: Usually 1:1
Atrial fibrillation is a serious public health concern because it is associated with __________ ?
Aging
What does A-Fib result from?
Atrial fibrillation happens when the heart’s upper chambers (atria) start beating in a fast and irregular way because the electrical signals controlling them aren’t working properly. Instead of a normal, steady heartbeat, the atria shake or quiver, making the heart beat unevenly. This can cause symptoms like a fast heartbeat, dizziness, or trouble breathing. It can also lead to blood clots because the blood isn’t flowing as smoothly as it should.
What are the 6 common characteristics of A-Fib?
Ventricular and atrial rate: Atrial rate is 300 to 600 bpm; ventricular rate is usually 120 to 200 bpm in untreated atrial fibrillation
Ventricular and atrial rhythm: Highly irregular
QRS shape and duration: Usually normal, but may be abnormal
P wave: No discernible P waves; irregular undulating waves that vary in amplitude and shape are seen and referred to as fibrillatory or f waves PR interval: Cannot be measured
P:QRS ratio: Many:1
Patients with A-Fib are at an increased risk of what?
Heart failure, myocardial ischemia, and embolic events such as stroke
Patients with A-fib may exhibit a pulse deficit, explain what this means.
A pulse deficit is a numeric difference between apical and radial pulse rates. The shorter time in diastole reduces the time available for coronary artery perfusion, thereby increasing the risk of myocardial ischemia with the onset of anginal symptoms
In patients with A-fib, what promotes the formation of thrombi?
The erratic nature of atrial contraction, alterations in ventricular ejection, and atrial myocardial dysfunction. . The origin of embolisms resulting in stroke for patients with nonvalvular atrial fibrillation is most often the left atrial appendage (LAA)
What is used to verify A-fib?
A 12 lead ECG.
What blood tests are used to screen for disease that are known to increase the risk of A-fib?
Thyroid, renal and hepatic functions.
What additional tests can be made w/ suspicion and diagnosis of A-fib?
chest x-ray (to evaluate pulmonary vasculature in a patient suspected of having pulmonary hypertension), exercise stress test (to exclude myocardial ischemia or reproduce exercise-induced atrial fibrillation), Holter or event monitoring.
How do we manage permanent A-fib medically?
Medical management revolves around preventing embolic events such as stroke with anticoagulant medications, controlling the ventricular rate of response with antiarrhythmic agents, and treating the arrhythmia as indicated so that it is converted to a sinus rhythm (i.e., cardioversion)
What pharmacological therapy can be used to manage A-fib?
Antithrombotic drugs may include anticoagulants and antiplatelet drugs.
Patients with atrial fibrillation with valvular heart disease or bioprosthetic heart valves may be prescribed warfarin, or a direct-acting oral anticoagulant, or a Factor Xa inhibitor.
Which medications may be given to achieve pharmacologic cardioversion from a-fib to sinus rhythm and whihc medication is the most preferred and why?
flecainide, dofetilide, propafenone, amiodarone, and IV ibutilide.
Dofetilide is a preferred medication because it is highly effective at converting atrial fibrillation to sinus rhythm, has fewer drug-to-drug interactions, and is better tolerated by patients than other medications.
What cholesterol lowering medications have proved to be effective to prevent new onset a-fib following cardiac surgery?
Statins (HMG-CoA reductase inhibitors)
What is the leading cause of death in the U.S?
Cardiovascular disease.
Which is the most prevalent type of cardiovascular disease in adults?
Coronary artery disease (CAD)
What is the most common cause of cardiovascular disease in the U.S?
Atherosclerosis.
Define Atherosclerosis.
Abnormal accumulation of lipid, or fatty substances, and fibrous tissue in the lining of arterial blood vessel walls. These substances block and narrow the coronary vessels in a way that reduces blood flow to the myocardium.
How does the inflammatory response involved with the development of atherosclerosis begin?
With injury t the vascular endothelium. The injury may be initiated by smoking or tobacco use, hypertension, hyperlipidemia, and other factors.
What does CO stand for, explain what CO is.
Cardiac Output.
CO= SV x HR
What is stroke volume?
The volume of blood that is being pushed out primarily by the left ventricle.
What is HR?
Hear Rate, how many beats per minute.
What is Preload?
Preload refers to the degree of stretch in the ventricles of the heart at the end of diastole, just before contraction.
In heart failure, increased preload can lead to congestion and fluid overload due to the heart’s inability to effectively pump out the extra volume.
What is afterload?
The resistance that the ventricles have to pump against / overcome.
What is ejection fraction?
(EF) The amount of blood ejected from the left ventricle during systole. Blood pumped out with each contraction.
Total volume would never be pumped out w/ each cotnraction.
What is the normal ejection fraction for a healthy adult?
50-70%
Explain hear failure with preserved ejection fraction (HFpEF)
This would be an example of diastolic failure - Left ventricular relaxation is impaired. This is the bodies attempt to compensate for dysfunction.
With HFpEF, what percentage usually determines that a person has got this?
more than 50%
Waht are some cuases of HFpEF?
- Hypertrophic cardiomyopathy (smaller ventricular volume)
- Restrictive cardiomyopathy (stiff ventricular walls)
- Myocardial fibrosis
- Pericardial constriction
Explain hear failure with reduced ejection fraction (HFrEF)
This is an example of systolic failure - Left ventricular contraction is impaired.
With HFrEF, what percentage usually determines that a person has got this?
Ejection fraction of less than 40%
What are the most common causes of HFrEF?
- Coronary Artery Disease
- volume Overload
- Dilated cardiomyopathy - ventricles stretched too much
- Valvular disease regurgitation - heart stretches but not valves, and valves cannot close properly.
- Increased Afterload - Increase in pressure
- Aortic or pulmonic stenosis
- Arrythmias - ventricles stretch and so does nerve endings.
Explain hear failure with midrange ejection fraction (HFmrEF)
Almost normal. This is a form of systolic failure, however the person may be asymptomatic.
With HFmrEF, what percentage usually determines that a person has got this?
40-49%
What can high EF (>75%) result in?
Hypertrophic cardiomyopathy.
What does a decrease in perfusion mean?
Cellular death or infarction.
If the heart is unable to pump enough blood to meet the body’s demands or needs, then they’re are said to be _______________
In heart failure.
When there is a problem with the contraction of the heart, it is a _________________ dysfunction.
systolic
When there is a problem with the filling of the heart, it is a _________________ dysfunction.
diastolic
What is the reason some patients experience diastolic dysfunction and some experience systolic dysfunction?
Reason is currently unknown.
Explain Cardiac compensation.
When there is an increase in oxygen demand in the body the heart tries to compensate for this.
Hoe does the Sympathetic nervous system compensate for increased oxygen demand via the heart?
Increases HR and force of contraction - faster and stronger contractions.
Explain increased preload in terms of cardiac compensation.
The heart does this bye dilated cardiomyopathy - the ventricles dilates to hold more blood - this often leads to weaker contractions due to prolonged stretch of the ventricles by blood volume. - good at first but then becomes a problem.
Why does Myocardial hypertrophy cause an increase in oxygen demand?
An increase in heart muscle mass = increase in oxygen demand of the heart - good at first but then becomes a problem.
What are the 3 non-modifiable risk factors of HF?
- Age > 60
- Male
- African American or Hispanic.
What are the 6 modifiable risk factors for HF?
- Smoking cessation
- Obesity
- Diabetes management
- ETOH - alcohol reduction
- Poor Diet
- Sedentary lifestyle.
True/False
Heart failure is almost always secondary to something else.
TRUE
What are some common causes of HF?
Coronary Artery Disease (CAD)
DM
HTN, PAH (Pulmonary arterial hypertension)
Cardiomyopathy
- Dilated cardiomyopathy (DCM)
- Hypertrophic cardiomyopathy (HCM)
Valvular Disorder
What does ADHF stand for?
Acute Decompensated Heart Failure.
Explain ADHF.
A = Acute
Decompensated = Deterioration of a structure or system previously working with the help of compensatory mechanisms.
Heart = organ that circulates blood
Failure = a state of insufficiency or declined performance leading to dysfunction of a body system.
Waht signs and symptoms will we see with ADHF?
- Tachypnea and SOB (shortness of breath)
- Pulmonary edema or flash pulmonary edema - lungs working against too much fluid build up around lungs.
- Pulmonary edema w / Hemoptysis (bloody sputum) - medical emergency
- crackles
- tachycardia
- Hypotension
- Severe dyspnea - shortness of breath.
- Orthopnea
- Use of accessory muscles to breathe
What is the most common cause of right sided HF?
Left sided HF
What are 2/3 of left sided HF the result of?
Systolic dysfunction (pumping)
Left ventricle cannot pump enough blood to go into systemic circulation, this increases the patients end diastolic pressure - fluid and pressure is forced back into the pulmonary system (this is why left causes right) - leading to pulmonary edema and flash pulmonary edema and impaired gas exchange.
Explain right sided HF.
Right ventricle cannot effectively pump blood into pulmonary circulation. The elevated pressure in the the pulmonary system reduces the amount of blood entering pulmonary circulation which leads to fluid backup in the systemic circulation.
What are 3 symptoms that right sided HF may cause?
Liver - Hepatomegaly
Abdomen - Ascites
Increased venous pressure (JVD & increased hydrostatic pressure in venous system)
Right sided HF is normally caused by left sided HF, but it can also be caused by ________________________ ?
Chronic lung disease (COPD) or cor pulmonale.
What are some clinical manifestations of left sided HF?
- Pulmonary congestion, crackles/rales
- S3 (lub dee dub) or “ventricular gallop”, tachycardia
- DOE (dyspneic of excretion) , SOB (shortness of breath), orthopnea
- Low o2 sat - due to impaired gas exchange
- Dry, non productive cough initially
- Oliguria
- Paroxysmal nocturnal dyspnea
- Fatigue, lethargy
What are some clinical manifestations of right sided HF?
- Visceral and peripheral congestion - fluid build up in organs and tissue
- Increased CVP (central venous pressure)
- Jugular venous distention (JVD)
- Peripheral edema - blood backing up in body
- Hepatomegaly
- Ascites
- Weight gain - fluid retention.
Is Congestive Heart failure usually right sided or left sided?
It is usually both.
With congestive heart failure, where do we normally see the congestion?
Lungs - pulmonary edema
Liver - Portal hypertension
Abdomen - ascites
To diagnose HF, what labs do we use?
BNP
CMP
Urinalysis
With suspicion of HF, what might a chest X-ray show?
Cardiomegaly - an enlarged heart.
What are some collaborative problems that patients may experience with HF?
- Pulmonary edema
- Hypotension, poor perfusion and cardiogenic shock
- arrythmias
- Thromboembolism
- Pericardial effusion
What are some ways that we can mange HF medically?
- Oral and IV medications
- Lifestyle modifications
- supplemental O2
- Surgical interventions : ICD, valve repair and heart transplant.
Why would we administer diuretics to a patient with HF?
To decrease fluid volume - we need to ensure that we are however monitoring electrolytes closely.
Why would we administer Angiotensin-converting enzyme (ACE) inhibitors to patients with HF?
They help reduce afterload by vasodilation, preload by reducing excess blood volume, and cardiac remodeling
Why would we administer Angiotensin II receptor blockers (ARB’s) to patients with HF?
Angiotensin II receptor blockers (ARBs) are used in heart failure (HF) treatment as an alternative to ACE inhibitors when patients cannot tolerate them (usually due to a persistent dry cough or angioedema). They provide similar hemodynamic and survival benefits by blocking the renin-angiotensin-aldosterone system (RAAS) but through a different mechanism.
Why would we administer Beta blockers (ARB’s) to patients with HF?
May be prescribed in addition to ACE inhibitor - may take several weeks to take effect. They counteracting the harmful effects of chronic sympathetic nervous system (SNS) activation - slows the heart rate
Explain the drug Ivabradine and why we give it to patients with HF?
Reduces the rate of conduction through the SA node - important to monitor patient for decreased HR and BP
Explain the drug Hydralazine and isosorbide dinitrate and why we give it to patients with HF?
Used as an alternative to ACE inhibitors - observe for decreased BP
Explain the drug Digitalis and why we give it to patients with HF?
Improves contractility - monitor for digitalis toxicity especially if patient is hypokalemic.
With patients hospitalized with ADHF, what drugs would we administer to them?
- Dopamine
- Dobutamine
- Milrinone
- Vasodilators
Explain why we would give Dopamine to a patient with ADHF.
This is a vasopressor to increase BP and myocardial contractility - should be used as an adjunct to loop diuretics to excrete extra fluid volume.
Explain why we would give Dobutamine to a patient with ADHF.
Used for patients with left ventricular dysfunction, it increased cardiac contractility and renal perfusion - helps heart beat stronger.
Explain why we would give Milrinone to a patient with ADHF.
Decreased preload and afterload, causes hypotension and may increase the risk of dysrhythmias.
Explain why we would give Vasodilators to a patient with ADHF.
IV nitro, nitroprusside, nesiritide - enhances symptom relief.
Older people may not present with the same symptoms of HF as younger people, what are some of the atypical symptoms that we may see with older patients?
Fatigue, weakness and somnolence.
What is the reason why diuretics may not be as effective in treating HF in older patients as it is with younger patients?
Older patients may have decreased renal function which may make the resistant to diuretic and more sensitive to changes in fluid volume. We may need to try different types of diuretics.
Why is it important to monitor older men on diuretics more closely?
They need to be observed for bladder distention caused by urethral obstruction from an enlarged prostate gland (BPH)
What goals should we set with patients with HF?
- Promote activity and reduce fatigue
- Relieve fluid overload
- Decrease anxiety
- Education for pt and family
- optimize treatment of co-morbidities.
What should the diet look like for patients with HF?
Low-sodium diet and fluid restriction.
What is normally the cause of Pulmonary Edema?
Left HF, blood begins backing up into the pulmonary system which will result in pulmonary edema.
Why does Pulmonary edema lead to hypoxemia?
All the fluid that is surrounding the lungs will impair the gas exchange at the alveolar level.
what are the clinical manifestations of Pulmonary Edema?
- Restlessness
- Anxiety
- Tachypnea
- Dyspnea
- Cool and clammy skin
- Cyanosis
- Weak and rapid pulse
- Cough
- Lung congestion
- increased sputum production
- decreased level of consciousness - CO2 buildup
how would we manage PE?
Prevention is easier than treatment.
Monitor lung sounds for signs of decreased activity tolerance and increased fluid retention.
Minimize exertion and stress
Provide oxygen via NRB ( non-rebreather), CPAP or BIPAP
Medication such as furosemide or vasodilators such as Nitroglycerin,
What nursing interventions should we do when caring for patients with PE?
- Positioning - sit them up to promote circulation.
- Psychological support
- Monitoring medications
- I&O
What is a Thromboembolism?
A thromboembolism is a condition where a blood clot (thrombus) forms in a blood vessel, dislodges, and travels through the bloodstream, blocking another vessel (embolism). This can lead to serious complications depending on where the clot lodges.
What is the reason patients with HF are at a greater risk of a thromboembolism?
More at risk for an arterial and venous thromboembolism. Because the blood isn’t moving properly it can form cloths due to coagulation. This may happen especially in patients with A-fib
With a pulmonary embolism, where does the clot normally come from?
The leg.
What does A-fib normally cause?
Strokes.
What is Pericardial Effusion?
The accumulation of fluid in the pericardial sac.
What is cardiac tamponade?
The restriction of heart function because of pericardial effusion, resulting in decreased venous return and decreased CO.
What are the clinical manifestations of Pericardial effusion ?
diffused chest pain or fullness
Pulsus paradoxus - what your hearing isn’t what you are feeling
Engorged neck veins
Labile or low BP - blood pressure changes rapidly
shortness of breath.
What are the cardinal signs of cardiac tamponade?
Sudden chest pain
Falling systolic BP
Narrowing pulse pressure
Rising venous pressure
Distant heart sound - due to fluid buildup.
How do we manage Pericardial effusion and cardiac tamponade medically?
Pericardiocentesis
Pericardiotomy
Explain Pericardiocentesis
Puncture of the pericardial sac to aspirate pericardial fluid
Explain Pericardiotomy
