Acute Coronary Syndrome and Myocardial Ischemia

Acute coronary syndrome (ACS) encompasses conditions resulting from myocardial ischemia, which occurs when the heart muscle does not receive enough oxygen. This can lead to various clinical manifestations, including:

Angina Pectoris: Temporary chest pain due to insufficient oxygen supply to the heart.
Acute Myocardial Infarction (AMI): A severe condition where heart muscle cells die due to prolonged ischemia.

Angina Pectoris

Angina pectoris is defined as chest pain that arises when the heart's demand for oxygen exceeds its supply, often triggered by physical or emotional stress. Key characteristics include:

Symptoms: Patients describe the pain as crushing or squeezing, often likened to the sensation of someone standing on their chest.
Location: Pain is usually felt in the mid-chest, under the sternum, and may radiate to the jaw, arms (especially the left arm), mid-back, or epigastric area.
Duration: Episodes generally last between 3 to 8 minutes, rarely exceeding 15 minutes.
Associated Symptoms: May include shortness of breath, nausea, and sweating.
Relief: Pain usually subsides with rest, supplemental oxygen, or nitroglycerin (NTG).

Although angina does not typically result in death or permanent heart damage, it serves as a critical warning sign.

Types of Angina

Unstable Angina: Occurs without a significant increase in oxygen demand and may happen at rest.
Stable Angina: Triggered by physical exertion or stress that exceeds the heart's capacity to supply blood.

Acute Myocardial Infarction (AMI)

The pain associated with AMI indicates actual myocardial cell death due to obstructed blood flow. Key points include:

Cell Death: Once heart cells die, they cannot be revived and will form scar tissue, impairing heart function.
Timeframe: Cell death begins approximately 30 minutes after blood flow is cut off, with significant damage occurring within 2 to 6 hours.
Intervention: Timely intervention with thrombolytic drugs or angioplasty can prevent permanent damage.
Transport: Immediate medical transport is crucial for improving outcomes.

Signs and Symptoms of AMI

Common signs and symptoms include:

Sudden weakness, nausea, and sweating.
Chest pain or pressure, often described as crushing or squeezing.
Pain radiating to the lower jaw, arms, back, abdomen, or neck.
Irregular heartbeat and potential syncope (fainting).
Shortness of breath (dyspnea).
Nausea and vomiting.
Pink, frothy sputum.
Risk of sudden death.

Differences Between AMI and Angina

The pain experienced during an AMI differs from angina in several ways:

AMI pain can occur at any time, not necessarily during exertion.
AMI pain lasts longer, typically from 30 minutes to several hours.
AMI pain may not be relieved by rest or nitroglycerin.
Patients may not recognize they are experiencing a heart attack.

Physical Findings in AMI

Physical examination may reveal:

General appearance: signs of fear, nausea, and poor circulation.
Pulse: may be faster, irregular, or bradycardic.
Blood pressure: can be decreased, normal, or elevated.
Respirations: may be normal or rapid and labored.
Mental status: feelings of impending doom.

Consequences of AMI

AMI can lead to serious complications, including:

Sudden Death: A critical risk associated with AMI.
Cardiogenic Shock: Occurs when the heart cannot pump enough blood, leading to inadequate oxygen delivery to tissues.
Congestive Heart Failure (CHF): Develops when the heart's ability to pump effectively is compromised, often following an AMI.

Dysrhythmias

Dysrhythmias are abnormalities in heart rhythm that can occur during an AMI:

Premature Ventricular Contractions (PVCs): Extra beats originating from a damaged ventricle.
Tachycardia: Rapid heart rate exceeding 100 beats per minute.
Bradycardia: Slow heart rate below 60 beats per minute.
Ventricular Tachycardia: Very rapid heart rhythm between 150 to 200 beats per minute, which can progress to ventricular fibrillation.
Ventricular Fibrillation: Disorganized quivering of the ventricles, leading to ineffective blood pumping and loss of consciousness within seconds. Defibrillation may restore normal rhythm.

Defibrillation and Asystole

Defibrillation is a life-saving procedure that involves delivering an electrical shock to restore normal heart rhythms:

It is most effective when administered within the first few minutes of sudden cardiac arrest.
CPR should be initiated until a defibrillator is available, as survival chances decrease by 7% to 10% each minute.

Asystole: The absence of all electrical activity in the heart, typically indicating prolonged ischemia, with a poor prognosis for survival.

Cardiogenic Shock

Cardiogenic shock is a critical condition often resulting from an AMI:

It occurs when the heart lacks the strength to pump sufficient blood, leading to inadequate oxygenation of body tissues.
Recognizing the early stages of shock is essential for effective management.

Congestive Heart Failure (CHF)

CHF may develop in the days following an AMI:

Characterized by an increased heart rate and left ventricular enlargement that fails to compensate for decreased heart function.
Fluid congestion in the lungs (pulmonary edema) can occur, leading to symptoms such as severe dyspnea and pink, frothy sputum.
Right-sided heart failure can cause fluid accumulation in other body areas, leading to dependent edema.

Assessment and Management of Chest Pain

1. Secondary Assessment

The secondary assessment is crucial for evaluating a patient's condition, particularly focusing on the cardiac and respiratory systems. Key components include:

Circulation: Assess the patient's blood circulation status.
Respirations: Evaluate the patient's breathing patterns.

Vital signs must be measured and recorded, which includes:

Pulse: Check the heart rate.
Respirations: Monitor the breathing rate.
Blood Pressure: Measure both systolic and diastolic blood pressures in both arms.
Pulse Oximetry: If available, utilize pulse oximetry to assess oxygen saturation.
Continuous Monitoring: If continuous blood pressure monitoring is available, implement it.
Documentation: Repeat vital sign measurements at appropriate intervals and document the time of each assessment.
12-lead ECG: In patients with chest pain, obtaining a 12-lead ECG as soon as possible is valuable for diagnosis.

2. Reassessment

Reassessing the patient is vital to ensure their condition is monitored effectively. Key points include:

Frequency: Reassess vital signs at least every 5 minutes or whenever significant changes occur.
Cardiac Arrest Protocol: If cardiac arrest occurs, initiate CPR immediately until an AED is available.
Intervention Review: Continuously reassess the effectiveness of interventions.
Patient Transport: Provide rapid transport to medical facilities if not already done.
Communication:
- Notify the emergency department about the patient's condition and estimated time of arrival.
- Follow medical control instructions.
- Document all assessments and treatments provided.

3. Emergency Medical Care for Chest Pain or Discomfort

When managing chest pain or discomfort, the following steps should be taken:

Comfort Position: Ensure the patient is in a comfortable position, allowing them to sit up if preferred, and loosen any tight clothing.
Oxygen Administration: Provide oxygen if indicated, and continually reassess the patient's respiratory status.
Oxygen Delivery Methods:
- Nasal cannula for mild dyspnea.
- Nonrebreathing face mask for severe respiratory distress.
- Consider CPAP for signs of pulmonary edema.
- Assist unconscious patients with breathing.
Aspirin Administration: Depending on protocol, prepare to administer low-dose aspirin and assist with prescribed nitroglycerin.

Aspirin

Mechanism: Prevents blood clots from forming or enlarging.
Dosage: Recommended dose is between 162 mg (two tablets) to 324 mg (four tablets), using 81 mg chewable tablets.

Nitroglycerin

Nitroglycerin is an essential medication in the management of chest pain. It is available in various forms:

Sublingual pill
Sublingual spray
Skin patch applied to the chest

Mechanism of Action: Nitroglycerin works by:

Relaxing blood vessel walls.
Dilating coronary arteries.
Increasing blood flow and oxygen supply to the heart.
Decreasing the workload of the heart.

Side Effects: Common side effects include:

Decreased blood pressure.
Severe headache.

Contraindications: Nitroglycerin should not be used if:

Systolic blood pressure is less than 100 mm Hg.
There is a presence of head injury.
The patient has used erectile dysfunction drugs within the last 24 to 48 hours.
The maximum prescribed dose has already been administered (usually 3 doses).

4. Cardiac Monitoring

For effective cardiac monitoring, it is essential that:

Electrodes are placed in consistent positions to ensure reliable ECG readings.
Basic principles are followed to minimize artifact in the ECG signal.

Cardiac Emergencies and Treatment Protocols

Importance of CPR and Early Defibrillation

CPR and early defibrillation are critical for increasing the chance of survival in cardiac emergencies.

Case Study: 59-Year-Old Woman with Chest Pressure

A 59-year-old woman presents with chest pressure. She is conscious and alert, but her skin appears cool, pale, and clammy.

First step in treatment: Administer oxygen.
Rationale:
- Patients with suspected cardiac issues should receive oxygen promptly.
- Obtaining vital signs and inquiring about nitroglycerin use are important but secondary actions.
- The AED is only for patients in cardiac arrest.

Considerations for Patients with Implanted Pacemakers

If a patient with an implanted pacemaker is in cardiac arrest, the EMT should:

Place AED pads away from the pacemaker.
Rationale:
- Placing AED pads directly over the pacemaker can hinder defibrillation and may damage the device.
- EMTs are trained to use AEDs and do not need to contact medical control before application.

Main Advantages of the AED

Quick delivery of a shock: The AED can administer shocks rapidly, which is crucial in cardiac emergencies.
Ease of use: The AED is simpler to operate than performing CPR.
No need for ALS providers: The AED can be used effectively without the presence of Advanced Life Support (ALS) providers.
Correct answer: All of the above.

Nitroglycerin Administration Protocol

After administering a nitroglycerin tablet to a patient, the EMT should:

Reassess the patient’s blood pressure within 5 minutes.
Rationale:
- Nitroglycerin is a vasodilator that can lower blood pressure.
- The tablet should dissolve under the tongue, not be chewed.
- Check the expiration date and ensure the medication is prescribed to the patient before administration.

Contraindications for Nitroglycerin Use

Nitroglycerin is contraindicated in patients:

With a systolic blood pressure less than 100 mm Hg: This is crucial as nitroglycerin can cause further drops in blood pressure.
Rationale:
- Patients who have taken erectile dysfunction (ED) drugs within the last 24 to 48 hours are also contraindicated due to the risk of severe hypotension.
- Chest pain duration and age alone are not contraindications for nitroglycerin use.

Left Ventricular Assist Devices (LVADs)

Left ventricular assist devices (LVADs) are medical devices designed to support patients with severe heart failure or those requiring temporary assistance following a myocardial infarction (MI).

Function: LVADs enhance the pumping ability of the left ventricle.
Common Design: Most LVADs feature an internal pump unit paired with an external battery pack.
Pulse Absence: Due to the continuous nature of the pumps, most patients will not exhibit a palpable pulse.
Device Management: Typically, EMTs will not need to manage the device unless a malfunction occurs. In such cases, contacting medical control is advised.
Transport Protocol: Ensure that all LVAD supplies and battery packs are transported with the patient.

Cardiac Arrest

Cardiac arrest is defined as the complete cessation of cardiac activity, which can be electrical, mechanical, or both.

Indicators: The absence of a carotid pulse is a key indicator of cardiac arrest.
Historical Context: Prior to the development of CPR and external defibrillation in the 1960s, cardiac arrest was typically fatal.
Survival Potential: With effective CPR, timely defibrillation, and access to advanced medical care, some patients can survive cardiac arrest without neurological damage.

Automated External Defibrillation (AED)

Overview

Automated external defibrillators (AEDs) are portable devices that analyze the heart's electrical signals and deliver shocks when necessary.

Functionality: AEDs identify ventricular fibrillation and are designed to administer shocks accurately.
Operator Interaction: All AED models require some level of operator interaction, such as applying pads and activating the device.
Voice Guidance: Many AEDs feature a computer voice synthesizer that guides users through the steps.
Semiautomated Design: Most AEDs are semiautomated, ensuring ease of use.

Advantages of AED Use

Efficiency: AEDs provide quick delivery of shocks, which is critical in cardiac arrest situations.
User-Friendly: They are designed to be easy to operate, allowing bystanders to assist without advanced training.
Independence from ALS: AEDs can be used effectively without the immediate presence of advanced life support (ALS) providers.
Safety: The adhesive pads used are safe and effective, with a larger area for better shock transmission.

Considerations for AED Use

Shock Necessity: Not all patients in cardiac arrest require a shock; AED analysis is crucial.
Asystole: This indicates a lack of electrical activity in the heart.
Pulseless Electrical Activity: Refers to a state where organized electrical activity exists without effective heart contractions.

Chain of Survival

Early defibrillation is vital for improving survival rates in cardiac arrest cases.

Key Links:
1. Early recognition and activation of emergency medical services (EMS).
2. Immediate bystander CPR.
3. Rapid defibrillation.
4. Basic and advanced EMS interventions.
5. ALS and postarrest care.
6. Recovery phase.

Integration of AED and CPR

Sequence of Care: AED and CPR should be administered in a coordinated manner.
Patient Interaction: Avoid touching the patient during AED analysis and shock delivery.
CPR Interruption: CPR must cease while the AED is delivering a shock.

AED Maintenance

Manufacturer Guidelines: Follow the manufacturer's recommendations for maintenance and operation.
Daily Checks: Conduct daily inspections of the AED at the start of each shift.
Common Errors: Be aware of frequent operational mistakes, such as failing to shock fine ventricular fibrillation or applying the AED incorrectly.
Documentation: Report any AED failures to the manufacturer and the FDA.

Emergency Medical Care for Cardiac Arrest

Preparation

Safety First: Ensure that the use of electricity from the AED does not harm anyone nearby.
Environmental Considerations: Avoid defibrillation in pooled water or when the patient is in contact with conductive materials.
Nitroglycerin Patch: Remove and clean the area of any nitroglycerin patches before defibrillation.
Patient Assessment: Determine the nature of injury (NOI) or mechanism of injury (MOI) and call for ALS assistance if needed.

Post-Defibrillation Protocol

Immediate Action: Begin chest compressions and attach the AED as soon as it is available.
Follow Protocol: Adhere to local protocols for patient care after AED use.
Outcomes: After AED use, the patient may either regain a pulse, not regain a pulse with no shock advised, or not regain a pulse with shock advised.

Continuing Care

ALS Coordination: If ALS is responding, continue CPR and shocks until they arrive.
Transport Protocol: If ALS is not responding, transport the patient when one of the following occurs:
1. The patient regains a pulse.
2. Six to nine shocks have been delivered.
3. The AED indicates no shock is advised after three consecutive messages.

Return of Spontaneous Circulation (ROSC)

Understanding the protocols for managing cardiac arrest is crucial for effective emergency medical care. The following scenarios outline the appropriate actions based on the patient's condition and the AED's indications:

No pulse, AED indicates no shock: Continue CPR and wait for Advanced Life Support (ALS) to arrive.
No pulse, AED indicates shock: Administer shock and continue CPR.
Transport considerations: Begin transport if:

The patient regains a pulse.
6 to 9 shocks have been delivered.
The AED gives three consecutive messages advising no shock after every 2 minutes of CPR.

Cardiac Arrest During Transport

When a cardiac arrest occurs while transporting a patient, immediate actions must be taken:

Stop the vehicle: This is the first step to ensure safety and effective resuscitation.
Begin CPR: If an AED is not immediately available, start CPR right away.
Call for ALS support: Notify ALS or other available resources based on the situation and local protocols.
Analyze the rhythm: Use the AED to assess the patient's heart rhythm.
Deliver shock if indicated: If the AED suggests, administer a shock and resume CPR.
Continue resuscitation: Follow local protocols for ongoing care.

Coordination with ALS Personnel

Effective communication and coordination with ALS personnel are vital during a cardiac arrest situation:

Use of AED: If an AED is available, do not wait for ALS to arrive before using it.
Notify ALS: Inform ALS personnel as soon as cardiac arrest is recognized.
Do not delay defibrillation: Immediate defibrillation is critical for patient survival.
Inform paramedics: When they arrive, provide them with a summary of actions taken up to that point.

Management of Return of Spontaneous Circulation

Once a patient regains a pulse, the following management steps should be taken:

Monitor respirations: Check for spontaneous breathing.
Provide oxygen: Use a bag-mask device to deliver oxygen at a rate of 10 breaths per minute.
Maintain oxygen saturation: Aim for SpO2 levels between 95% and 99%.
Assess blood pressure: Regularly check the patient's blood pressure.
Patient interaction: See if the patient can follow simple commands.
Transport: If ALS is not on scene or en route, begin transport to the nearest appropriate hospital as per local protocol.

Signs and Symptoms of Cardiac Ischemia

Recognizing the signs and symptoms of cardiac ischemia is essential for timely intervention:

Common symptoms include:

Chest pressure or pain.
Shortness of breath (dyspnea).
Anxiety or restlessness due to hypoxia and decreased cardiac output.

Uncommon symptom: Headache is not typically associated with cardiac ischemia.

Understanding Dysrhythmia

When assessing a patient with chest pain, the presence of an irregular pulse can indicate a serious condition:

Irregular pulse: Suggests dysrhythmia, an abnormality in the heart's electrical system.
Monitoring: Patients with signs of cardiac compromise and an irregular pulse should be closely monitored for potential cardiac arrest.

Acute Myocardial Infarction (AMI)

Identifying the cause of an AMI is crucial for treatment:

Blocked blood vessels: The coronary arteries supply oxygen-rich blood to the heart muscle. Blockage leads to AMI.
Controllable risk factors: Cigarette smoking is a major controllable risk factor for cardiovascular diseases, including AMI.

Survival Chances in Cardiac Arrest

Survival rates from cardiac arrest, particularly due to ventricular fibrillation, are influenced by several factors:

Immediate CPR: Initiating CPR promptly increases chances of survival.
Defibrillation: Providing defibrillation within 2 minutes of cardiac arrest is critical for survival.
Transport and oxygen: While important, they are secondary to the immediate need for CPR and defibrillation.

Initial Care for Chest Pain Patients

When encountering a patient with chest pressure, the first step in treatment should be:

Administer oxygen: This is the priority for any patient with suspected cardiac issues.
Follow-up actions: While obtaining vital signs and checking for nitroglycerin use are important, oxygen administration is paramount.

Cardiovascular Emergencies

National EMS Education Standard Competencies

Pathophysiology: Understanding the pathophysiology of respiration and perfusion is crucial for effective patient assessment and management.
Medicine: Application of fundamental knowledge to deliver basic emergency care and transportation based on assessment findings for acutely ill patients.
Cardiovascular: Knowledge of anatomy, signs, symptoms, and management related to:
- Chest pain
- Cardiac arrest
Advanced Cardiovascular Conditions: Understanding anatomy, physiology, pathophysiology, assessment, and management of conditions such as:
- Acute coronary syndrome
- Angina pectoris
- Myocardial infarction
- Aortic aneurysm/dissection
Additional Cardiovascular Issues: Knowledge of:
- Thromboembolism
- Heart failure
- Hypertensive emergencies

Introduction to Cardiovascular Disease

Cardiovascular disease has been the leading cause of death in Americans since 1900, accounting for approximately 1 in every 3 deaths.
EMS plays a critical role in reducing mortality rates through various strategies:
- Encouraging healthy lifestyle choices
- Facilitating early access to medical care
- Increasing CPR training among laypeople
- Utilizing evolving technology in dispatch and cardiac arrest response
- Ensuring public access to defibrillation devices
- Recognizing the need for advanced life support (ALS)
- Utilizing cardiac specialty centers when available

Anatomy and Physiology of the Heart

The primary function of the heart is to pump blood, supplying oxygen-enriched red blood cells to body tissues.
The heart is divided into left and right sides:
- Upper chambers (atria) receive incoming blood.
- Lower chambers (ventricles) pump outgoing blood.
Blood flows through the heart via one-way valves, ensuring proper circulation:
- The aorta, the body's main artery, receives blood ejected from the left ventricle and distributes it to the body.
The heart's electrical system regulates heart rate and coordinates the contractions of the atria and ventricles:
- Electrical impulses originate at the SA node and travel through the heart.
- Automaticity allows the heart to generate impulses spontaneously, maintaining a consistent rhythm.

Emergency Medical Care for Chest Pain or Discomfort

Nitroglycerin

Nitroglycerin is a medication commonly used in the management of chest pain. It works by relaxing blood vessels, which increases blood flow to the heart and decreases the workload on the heart.

Side Effects

Decreased blood pressure: This can lead to dizziness or fainting.
Severe headache: Often a result of vasodilation.

Contraindications

Systolic blood pressure: Should be greater than 100 mm Hg.
Head injury: Risk of increased intracranial pressure.
Erectile dysfunction drugs: Use within the last 24 to 48 hours can lead to severe hypotension.
Maximum prescribed dose: Typically, the maximum is three doses.

Cardiac Monitoring

Electrode Placement

For an ECG (electrocardiogram) to be reliable, electrodes must be placed in consistent positions. Proper placement minimizes artifact and ensures accurate readings.

Guiding Principles for Electrode Placement

Shave body hair if necessary to ensure good contact.
Clean the electrode site with an alcohol swab to remove oils and dead skin.
Attach electrodes to ECG cables before placing them on the patient.
Confirm the correct placement of electrodes on the patient's chest or limbs.

Monitoring Procedure

Once electrodes are in place, turn on the monitor.
Print a sample rhythm strip.
If the strip shows artifact, check that electrodes are firmly applied and the cable is properly connected.

Heart Surgeries and Cardiac Assistive Devices

Overview of Heart Surgeries

Over the past 40 years, numerous open-heart surgeries have been performed to address coronary artery issues.

Coronary Artery Bypass Graft (CABG)

A blood vessel from the chest or leg is sewn from the aorta to a coronary artery beyond an obstruction.

Percutaneous Transluminal Coronary Angioplasty (PTCA)

A tiny balloon is inflated inside a narrowed coronary artery to widen it.
Steps involved include:
- Introducing a balloon attached to a long tube into the artery.
- Inflating the balloon to dilate the artery.
- Deflating and removing the balloon and tube.
- Sometimes, a stent is placed to keep the artery open.

Post-Surgery Considerations

Patients may have visible chest scars, but treatment for chest pain should follow standard protocols regardless of surgical history.
Some patients may have implanted cardiac pacemakers to regulate heart rhythm.

Cardiac Pacemakers

Pacemakers are devices that maintain a regular heart rhythm by delivering electrical impulses through wires in contact with the myocardium.
They are typically implanted under the skin in the upper left chest.
Reliable technology, but malfunction can lead to symptoms such as syncope, dizziness, or weakness.
Patients with malfunctioning pacemakers should be transported promptly to a medical facility.
During CPR, avoid placing AED pads directly over the pacemaker.

Automatic Implantable Cardiac Defibrillators (AICDs)

AICDs are used by patients who have survived cardiac arrest due to ventricular fibrillation.
These devices monitor heart rhythm and deliver shocks as needed.
Treat patients with AICDs as you would other patients experiencing an acute myocardial infarction (AMI).
The electricity from AICDs is low and does not pose a risk to rescuers.

External Defibrillator Vest

A wearable vest with built-in electrodes and defibrillation pads.
Connected to a monitor and capable of delivering high-energy shocks.
Do not touch the patient if the device warns of an impending shock.
Keep the vest on during CPR unless it interferes with compressions.

Left Ventricular Assist Devices (LVADs)

LVADs are used to enhance the pumping function of the left ventricle in patients with severe heart failure or during recovery from an MI.
Commonly consist of an internal pump and an external battery pack.
Most patients will not have a palpable pulse due to continuous pumping.
Transport all LVAD supplies and battery packs with the patient.

Cardiac Arrest

Cardiac arrest is defined as the complete cessation of cardiac activity, requiring immediate medical intervention.

Oxygen Supply to the Body

The circulatory system is responsible for supplying oxygenated blood to various parts of the body through a network of arteries. The key arteries involved include:

Right and Left Carotid Arteries: Supply blood to the head and brain.
Right and Left Subclavian Arteries: Supply blood to the upper extremities.
Brachial Artery: Supplies blood to the arms.
Radial and Ulnar Arteries: Supply blood to the lower arms and hands.
Right and Left Iliac Arteries: Supply blood to the groin, pelvis, and legs.
Right and Left Femoral Arteries: Supply blood to the legs.
Anterio and Posterior Tibial and Peroneal Arteries: Supply blood to the lower legs and feet.

Smaller Vessels: Arterioles and Capillaries

Arterioles and capillaries are smaller blood vessels that play a crucial role in the circulatory system:

Arterioles: Smaller branches of arteries that lead to capillaries.
Capillaries:
- One-cell thick, allowing for efficient exchange.
- Facilitate the exchange of nutrients and oxygen for waste at the cellular level.
- Connect arterioles to venules.
Venules: The smallest branches of veins that receive blood from capillaries.
Venae Cavae: Major veins that return deoxygenated blood to the heart:
- Superior Vena Cava: Carries blood from the head and arms to the right atrium.
- Inferior Vena Cava: Carries blood from the abdomen, kidneys, and legs to the right atrium.

Components of Blood

Blood is composed of several types of cells and fluid:

Red Blood Cells: Carry oxygen and remove carbon dioxide.
White Blood Cells: Fight infection.
Platelets: Help in blood clotting.
Plasma: The fluid in which blood cells float.

Blood Pressure

Blood pressure is the force exerted by circulating blood against artery walls:

Systolic Blood Pressure: The maximum pressure generated by the left ventricle during contraction (systole).
Diastolic Blood Pressure: The pressure against artery walls while the left ventricle is at rest.

Pulses in the Body

A pulse is felt when blood passes through an artery during systole:

Peripheral Pulses: Felt in the extremities (e.g., radial and posterior tibial).
Central Pulses: Felt near the trunk of the body (e.g., femoral and carotid).

Common Pulse Points

Common pulse points in the body include:

Carotid Pulse: Felt in the neck.
Femoral Pulse: Felt in the groin area.
Brachial Pulse: Felt on the inside of the upper arm.
Radial Pulse: Felt on the thumb side of the wrist.
Posterior Tibial Pulse: Felt on the inside of the ankle.
Dorsalis Pedis Pulse: Felt on the top of the foot.

Cardiac Output and Perfusion

Cardiac output is the volume of blood that passes through the heart in one minute:

Calculation: Cardiac output = Heart rate × Stroke volume.
Stroke Volume: The volume of blood ejected with each contraction.
Perfusion: The constant flow of oxygenated blood to tissues; requires:
- A well-functioning heart.
- An adequate volume of blood.
- Proper constriction of blood vessels to match blood volume.
If perfusion fails, it can lead to cellular death and ultimately patient death.

Pathophysiology of Ischemic Heart Disease

Chest pain is often a result of ischemia, which is decreased blood flow to tissues:

Ischemic Heart Disease: Characterized by reduced blood flow to one or more portions of the heart muscle. If not restored, tissue death occurs.

Atherosclerosis

Atherosclerosis involves the buildup of calcium and cholesterol in the arteries:

Causes obstruction in blood flow to the heart.
Fatty material accumulates over time, narrowing the lumen of the arteries.
The inner wall becomes rough and brittle, increasing the risk of plaque rupture and blood clot formation.

Thromboembolism

A thromboembolism is a blood clot that travels through blood vessels:

If it lodges in a coronary artery, it can lead to acute myocardial infarction (AMI).
Downstream tissues suffer from hypoxia, and prolonged blockage can result in tissue death.

Coronary Artery Disease

Coronary artery disease is the leading cause of death in the United States:

Controllable Risk Factors:
- Cigarette smoking.
- High blood pressure.
- High cholesterol.
- Diabetes.
- Lack of exercise.
- Obesity.
Uncontrollable Risk Factors:
- Older age.
- Family history.
- Race and ethnicity.
- Being male.

Acute Coronary Syndrome (ACS)

ACS is a group of symptoms caused by myocardial ischemia:

Includes conditions such as angina pectoris and acute myocardial infarction (AMI).

Angina Pectoris

Angina pectoris occurs when the heart's oxygen demand exceeds supply:

Characterized by crushing or squeezing pain.
Does not typically lead to death or permanent heart damage but is a serious warning sign.
Often triggered by physical or emotional stress, large meals, or sudden fear.
Pain usually subsides when the increased oxygen demand is alleviated.

Anatomy and Physiology of the Heart and Circulatory System

The Aorta and Blood Circulation

The aorta is the body's main artery, responsible for receiving oxygen-rich blood ejected from the left ventricle of the heart. It then delivers this blood to all other arteries that supply the body's tissues.

Blood Flow Through the Heart

Blood circulation through the heart is divided into two main pathways:

Right Side of the Heart: Receives oxygen-poor blood from the venous circulation.
Left Side of the Heart: Receives oxygen-rich blood from the lungs via the pulmonary veins.

These processes are illustrated in the accompanying figures, which depict how blood circulates through the heart.

The Heart's Electrical System

The heart's electrical system is crucial for controlling heart rate and coordinating the contraction of the atria and ventricles:

Electrical Impulses: Initiated at the sinoatrial (SA) node, these impulses spread from the atria to the ventricles.
Automaticity: The heart's ability to contract spontaneously without external nerve stimulation. Myocardial cells can generate their own impulses if the SA node fails to do so.

This self-regulating mechanism ensures that the heart continues to function effectively even in the absence of external stimuli.

Electrical Conduction System

The electrical conduction system of the heart regulates heart rate and ensures that the four chambers work in harmony. Key components include:

SA Node: The primary pacemaker of the heart.
AV Node: Acts as a gatekeeper, controlling the electrical signals from the atria to the ventricles.

These components work together to maintain a consistent and effective heartbeat.

Autonomic Nervous System (ANS)

The autonomic nervous system (ANS) is responsible for controlling involuntary activities within the body and consists of two main branches:

Sympathetic Nervous System: Prepares the body for 'fight or flight' responses, increasing heart rate and blood flow to muscles.
Parasympathetic Nervous System: Promotes 'rest and digest' functions, slowing the heart rate and conserving energy.

These two systems typically work in balance to regulate bodily functions.

Myocardium and Cardiac Output

The myocardium, or heart muscle, requires a continuous supply of oxygen and nutrients to function effectively:

Cardiac Output: The volume of blood the heart pumps per minute, which can be increased by raising either heart rate or stroke volume.
Coronary Arteries: These arteries supply blood to the myocardium. They dilate to meet the increased oxygen demands of the heart muscle.

Coronary Arteries

The coronary arteries are vital for supplying blood to the heart muscle:

Right Coronary Artery: Supplies blood to the right atrium, right ventricle, and often the inferior wall of the left ventricle.
Left Coronary Artery: Supplies blood to the left atrium and left ventricle, branching into two major arteries shortly after originating from the aorta.

Figures illustrating the blood flow to the heart highlight the importance of these arteries in maintaining cardiac health.

Arteries Supplying the Body

Various arteries distribute oxygenated blood throughout the body:

Carotid Arteries: Right and left carotid arteries supply blood to the head and brain.
Subclavian Arteries: Right and left subclavian arteries supply blood to the upper extremities.
Brachial Artery: Supplies blood to the arms.
Radial Arteries: Supply blood to the lower arms and hands.
Iliac Arteries: Right and left iliac arteries supply the groin, pelvis, and legs.
Femoral Arteries: Right and left femoral arteries supply the legs.
Tibial and Peroneal Arteries: Anterior and posterior tibial and peroneal arteries supply the lower legs and feet.

Smaller Vessels: Arterioles and Capillaries

Arterioles and capillaries are smaller blood vessels that play a crucial role in the circulatory system:

Arterioles: Small branches of arteries that lead to capillaries.
Capillaries: Microscopic vessels that connect arterioles to venules, facilitating the exchange of oxygen, nutrients, and waste products between blood and tissues.

Pathophysiology of Congestive Heart Failure and Hypertensive Emergencies

Congestive Heart Failure (CHF)

CHF often develops within a few days following a myocardial infarction (heart attack). The condition arises when the heart's increased rate and left ventricular enlargement fail to compensate for its decreased function.

Fluid Congestion: The lungs become congested with fluid, leading to pulmonary edema.
Symptoms:
- Acute-onset CHF may present with severe pulmonary edema, characterized by pink, frothy sputum and severe dyspnea (difficulty breathing).
- CHF can develop suddenly or gradually over months.
Right-Sided Heart Failure: This occurs when blood backs up in the vena cavae, causing fluid accumulation in other body parts, leading to dependent edema (e.g., swelling in feet and legs).
Consequences:
- Inadequate blood supply to the left ventricle can cause a drop in systemic blood pressure.
- Patients may exhibit signs of both left- and right-sided heart failure, as left-sided failure often leads to right-sided failure.

Hypertensive Emergencies

Hypertensive emergencies are defined as any systolic blood pressure exceeding 180 mm Hg or a rapid increase in systolic pressure.

Common Symptoms:
- Sudden, severe headache.
- Strong, bounding pulse.
- Ringing in the ears.
- Nausea and vomiting.
- Dizziness.
- Warm skin (either dry or moist).
- Nosebleeds.
- Altered mental status.
- Sudden pulmonary edema.
Risks: If untreated, hypertensive emergencies can lead to severe complications such as stroke or dissecting aortic aneurysm.
Transport Considerations: Patients should be transported quickly and safely, with consideration for Advanced Life Support (ALS) assistance based on transport distance and time.

Aortic Aneurysm

An aortic aneurysm is characterized by a weakness in the wall of the aorta, making it susceptible to rupture.

Types:
- Dissecting Aneurysm: Occurs when the inner layers of the aorta separate, allowing high-pressure blood to flow between the layers.
Primary Cause: Uncontrolled hypertension is the leading cause of dissecting aortic aneurysms.
Signs and Symptoms:
- Very sudden chest pain, often described as coming on full force.
- Different blood pressures may be observed in various locations.
- Differentiating between a dissecting aneurysm and acute myocardial infarction (AMI) can be challenging.
Transport Considerations: Rapid transport to a medical facility is crucial to improve patient outcomes.

Scene Size-up

During patient assessment, the initial scene size-up is critical for ensuring safety and understanding the nature of the illness (NOI).

Safety: Ensure the scene is safe and follow standard precautions.
Gathering Information: Obtain clues from dispatch, the scene, and comments from family members and bystanders.

Primary Assessment

The primary assessment involves forming a general impression and assessing airway and breathing.

General Impression:
- If the patient is unresponsive and not breathing, initiate CPR and call for an AED.
Airway and Breathing Assessment:
- For oxygen saturation below 95%, administer oxygen via nasal cannula at 4 L/min.
- If the patient is not breathing or has inadequate breathing, provide 100% oxygen using a bag-mask device.
- In cases of pulmonary edema, utilize positive pressure ventilation with a bag-mask device or CPAP.

Circulation Assessment

Evaluating circulation is essential in the primary assessment.

Check:
- Pulse rate and quality.
- Skin color, moisture, and temperature.
- Capillary refill time.
Considerations:
- Treatment for cardiogenic shock should be initiated early to reduce the workload on the heart.
- Position the patient comfortably, typically sitting up and well supported.
Transport Decision:
- Make transport decisions based on the stabilization of life threats during the primary assessment.
- Most patients with chest pain should be transported immediately, following local protocols for the appropriate receiving facility.
- Consider using lights and sirens based on estimated transport time.
- Transport patients with cardiac issues in a gentle, stress-relieving manner.

History Taking

History taking is crucial for understanding the patient's condition.

Chief Complaint: Investigate the primary issue, such as chest pain or difficulty breathing.
SAMPLE History:
- Ask about previous heart attacks, known heart problems, and risk factors for coronary artery disease.
- Inquire about allergies and current medications.
OPQRST: Use this mnemonic to assess pain characteristics.

Secondary Assessment

The secondary assessment focuses on a thorough physical examination.

Focus Areas: Concentrate on the cardiac and respiratory systems.
Vital Signs:
- Measure and record pulse, respirations, and blood pressures in both arms.
- If available, utilize pulse oximetry and continuous blood pressure monitoring.
- Repeat vital signs at appropriate intervals and document the timing of each measurement.
- In patients with chest pain, obtaining a 12-lead ECG early is valuable.

Reassessment

Reassess vital signs at least every 5 minutes or as the patient's condition changes to ensure ongoing evaluation and care.

Acute Coronary Syndrome: Diagnosis and Emergency Care

Acute Coronary Syndrome: Diagnosis and Emergency Care