Chapter 14: Cardiovascular Emergencies Flashcards
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Heart’s electrical system
Impulses from begin in sinus node (sinoatrial node) in superior right atrium, trvael across atria causing contraction, cross AV node where signal is delayed 0.1-0.2 s, then to ventricles via Purkinje fibers
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Automaticity
In heart muscle, muscle can contract without nerve stimulus
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Two parts of autonomic nervous system
Sympathetic: fight or flight, physical activity. Parasympathetic: Opposite of sympathetic
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Anatomy of coronary arteries
Come from aorta just superior to aortic valve. Left and right. Left splits into circumflex branch which branches posteriorly to descending coronary artery in posterior interventricular groove. Right supplies right ventricle and usually the inferior wall of left ventricle.
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Anatomy of descending aorta
Branches at umbilicus to the iliac arteries. They become the femoral arteries. At knee, becomes popliteal then brances to anterior and posterior tibial arteries and posterior branches to peroneal
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Anatomy of ascending aorta
Branches into subclavian and carotid arteries
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Cardiac output
Volume of blood pumped in 1 min
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Atherosclerosis
Calcium and cholesterol buildup form plaque. Forms partial occlusion. Can crack and cause clotting, completely occluding vessel.
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Thromboembolism
Blood clot embolism
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Acute myocardial infarction
AMI. Blockage occuring in coronary artery leads to death of heart tissue (infarction). Pain comes from cell death. 30 minutes after flow cut off, cells begin to die.
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Acute coronary syndrome
A group of symptoms caused by myocardial ischemia.
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Angina pectoris
Myocardial ischemia for a short time (Typically 3-8 min, rarely longer than 15). When heart’s needs exceed supply, often during exertion or emotional stress. Described as crushing, typically under sternum but can radiate to left arm, jaw, mid back, epigastrium.
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Stable vs. unstable angina pectoris
Unstable: progressively less exertion required to stimulate angina (untreated can lead to AMI). Stable: relieved by things that normally relieve it.
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What should EMT always treat chest pain as?
Potential AMI
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AMI vs. acute angina pectoris difference
- AMI can occur at any time rather than just exertion.
- AMI does not resolve in a few minutes.
- May or may not be relieved by nitro
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What pt groups can often have AMI without chest pain?
Females and diabetics
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Consequences of AMI
Sudden death, cardiogenic shock, CHF
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Arrythmias
Tachycardia, bradycardia, ventricular tachycardia (150-200 bpm, impulse starts in ventricles not SA node, insufficient time to refill with blood), ventricular fibrillation (quivering), asystole (absence of electrical activity)
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CHF
Usually between first few hours and days after AMI, also from diseased heartvalves and chronic hypertension. Causes pulmonary edema, quickly as in AMI or over time as in chronic CHF. Right sided CHF causes dependent edema.
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Hypertensive emergency
Systolic > 160 or rapid rise in systolic (Normal hypertension is systolic>140 or diastolic>90). S/S: sudden, severe headache. Can lead to stroke or dissecting aortic aneurysm.
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Dissecting aortic aneurysm
Aorta likely to rupture from delamination of wall. S/S sudden onset of sharp stabbing pain, not crushing.
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AED
Automated external defibrillator. Biphasic shock defibs more efficiently and with lower energy than monophasic (120 J vs. 360 J).
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Protocol for attaching AED when cardiac arrest witnessed vs. not
Witnessed: Apply AED immediately. If not (>5 min to scene), perform 5 cycles of CPR.
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Nitroglycerin
Vasodilator. Max of three doses usually. Contraindicated by BP<100 or ED meds in last 24 hours.
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Cardiogenic shock
When heart lacks enough power to acheive adequate cardiac output. More commonly found in AMI that affects inferior and posterior regions of left ventricle.
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Preferred position of transport for CHF pt’s
Sitting with legs down to avoid pooling of fluids in torso.
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4 links in chain of survival for cardiac arrest
Recognition of early warning signs and activation of EMS, immediate bystander CPR, early defibrillation, early ALS
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Bradycardia
<60 bpm
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Cardiac arrest
Heart fails to generate effective/detectable blood flow. Pulses not palpable, even if muscular or electrical activity continues in heart
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Tachycardia
>100bpm
S/S
AMI
- sudden onset weakness, nausea, etc;
- chest pain or crushing feeling that doesn’t change with breath
- radiated pain
- irregular heartbeat
- syncope
- dyspnea
- pink sputum
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Timeframe of angina pectoris?
3-8 min. Rarely longer than 15 min.
