Chapter 17: Ready for Review
• Cardiovascular disease has been the number one killer in the United States almost every
year since 1900.
• The cardiovascular system is composed of the heart and blood vessels. Its primary function
is to deliver oxygenated blood and nutrients to every cell.
• The body attempts to maintain a fairly constant blood pressure to ensure perfusion of vital
organs.
• Patients experience a variety of symptoms when they have a cardiovascular problem, the
most common of which are chest pain, dyspnea, fainting, palpitations, and fatigue.
• Patients with cardiovascular disease are often prescribed several medications. Patients with
advanced age typically experience more side effects from medications than do younger
patients. Adverse drug events account for approximately 10% of all ED visits in the elderly.
• Cardiac rhythm disturbances (dysrhythmias) may arise from a variety of causes, including
AMI.
• One of the most important tasks in the prehospital care of a patient with an AMI is to
anticipate, recognize, and treat life-threatening dysrhythmias. In fact, ECG analysis is
indicated in any patient who might have a cardiac-related condition.
• Most deaths from AMI are due to dysrhythmias, which typically occur during the early
hours of the infarct.
• Cardiac monitors consist of leads that are connected to electrodes, which are placed on the
patient. Each lead offers an electrical snapshot of a certain part of the heart. The cardiac
monitor records the electrical activity acquired by each lead used, resulting in a 12-lead
ECG tracing.
• Cardiac monitoring and ECG analysis are indicated in any patient who might have a
cardiac-related condition. Any patient with chest pain or a history of heart problems should
undergo ECG analysis.
• Cardiac monitoring usually involves using four limb leads to create an ECG printout
showing lead I, II, and III to monitor the electrical activity in the patient’s heart.
• Components of a rhythm strip produced by an ECG include the P wave, PR interval, QRS
complex, J point, ST segment, T wave, and QT interval.
• Each component of the rhythm strip represents a phase of electrical activity within the
heart. One whole complex on a rhythm strip represents one complete cycle of electrical
conduction.
• Items to assess when you are analyzing a rhythm strip or ECG include the following: P
waves, the PR interval, QRS duration, rhythm, and rate.
• The 12-lead ECG enables localization of cardiac ischemia to specific areas of the heart. The
12 leads include three limb leads (I, II, and III), three augmented limb leads (aVR, aVL, and
aVF), and six precordial leads (V1 to V6).
• Leads that look at the same general area of the heart are called contiguous leads.
• Transmission of 12-lead ECG findings to the receiving facility is an important step that can
lead to a faster diagnosis, decrease the time from emergency onset to definitive therapy
(door-to-balloon time and door-to-needle time), and decrease mortality.
• Management of cardiac arrest involves BLS and ALS skills, including CPR, defibrillation,
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cardiac monitoring, IV fluid or medication infusion, post-resuscitative care, and cooling.
Defibrillation is an intervention used to interrupt rapid chaotic rhythms such as ventricular
tachycardia and ventricular fibrillation. Defibrillation simultaneously depolarizes all cardiac
tissue in hopes of allowing the SA node to resume the function of primary pacemaker.
Paramedics most often perform manual defibrillation rather than automated external
defibrillation, because they are trained in interpreting cardiac rhythms.
Synchronized cardioversion is an intervention used to interrupt rapid, organized, and
hemodynamically unstable rhythms such as supraventricular tachycardia and
atrial fibrillation. Unlike defibrillation, synchronized cardioversion is timed or
“synchronized” to the patient’s cardiac rhythm. Energy is delivered precisely at the peak of
the R wave to capitalize on the already depolarized state of the ventricles. The energy
delivered during synchronized cardioversion is aimed at depolarizing any tissue that
remains polarized in hopes that the SA node resumes the primary pacemaking function.
Transcutaneous pacing is an intervention used to depolarize heart muscle using an external
stimulus. Pads placed on the patient’s chest deliver electrical energy to the heart, causing
muscle contraction. The external pacemaker serves as a bridge to permanent internal
pacemaker implantation. Transcutaneous pacing is used to treat patients with
hemodynamically unstable bradycardias.
Treatment of hemodynamically unstable dysrhythmias should be centered on rate control of
the dysrhythmia using electrical therapies.
Most cardiac arrest victims have evidence of atherosclerosis or other underlying cardiac
disease. However, cardiac arrest can also occur secondary to electrocution, submersion, and
other types of trauma. Indeed, many cardiac arrest victims have no warning before the event
occurs.
Coronary artery disease is the most common form of heart disease and the leading cause of
death in adults in the United States.
Cardiac tamponade occurs when excessive fluid accumulates within the pericardium,
limiting the heart’s ability to fully expand. This can reduce cardiac filling to the point that
the heart is unable to circulate blood. Emergent pericardiocentesis is lifesaving in patients
with cardiac tamponade and hemodynamic instability. Transport the patient to the closest
emergency facility.
Cardiogenic shock results from extensive injury to the myocardium and carries a high
mortality rate. Transport the patient expeditiously to the hospital. Except for the correction
of life-threatening dysrhythmias, there are no measures that can stabilize the condition of a
patient in cardiogenic shock in the field.
Aortic aneurysms—particularly acute dissecting aneurysms of the thoracic aorta and
expanding or ruptured aneurysms of the abdominal aorta—are of greatest concern to the
EMS responder. The most common chief complaint is sudden severe ripping or tearing
pain in the chest or abdomen.
Treatment of hypertensive emergencies includes slow, controlled lowering of the patient’s
blood pressure. Management of elevated blood pressure should be reserved for the
emergency department physician. Remember that systemic hypertension can be a result of
increased intracranial pressure and is essential to maintain cerebral perfusion pressure.