Acute Coronary Syndrome Flashcards
What is the definition of ACS ?
It is a spectrum of syndromes ranging from unstable angina- NSTEMI- STEMI.
What is the pathophysiology of ACS?
Coronary artery occlusion due to atherosclerotic or thrombotic emboli causing ischaemia which if not reversed leads to myocardial infarct and necrosis.
What is the pathophysiology of stable angina ?
stable angina occurs when the coronary vessels fail to meet the myocardial O2 demand during exercise or stress. It occurs mainly due to the stenosis of the coronary vessels and vasospasm.
what are the four main factors that contribute to increased O2 demand?
Heart rate, systolic blood pressure, myocardial wall tension, and myocardial contractility.
What are the four factors that determine the myocardial blood flow?
Coronary artery diameter and tone, collateral blood flow, perfusion pressure, and heart rate
what is the pathophysiology of chest pain ?
Myocardial ischemia stimulates chemosensitive and mechanoreceptive receptors within the cardiac muscle fibers and the surrounding coronary vessels. This triggers impulses through the sympathetic afferent pathways from the heart to the cervical and thoracic spine. Each spinal level has a corresponding dermatome; the discomfort described by the patient will often follow the specific dermatomal pattern.
What is the pathophysiology of unstable angina ?
The pathophysiology of unstable angina is a combination of intraluminal plaque formation, intraluminal thrombosis, vasospasm, and elevated blood pressure causing obstruction of the blood flow to the myocardium.
What is the pathophysiology of NSTEMI ?
Subtotal occlusion of the coronary vessel causing subendocardial ischaemia.
What is the pathophysiology of STEMI ?
It occurs due to complete occlusion of the epicardial artery causing extensive transmural ischaemia and myocardial infarction.
What are the classical symptoms of heart attack ?
- Anxiety, diaphorosis, pallor, crushing substernal chest pain, and dyspnoea.
What is the atypical presentation of heart attack ?
The most common atypical symptoms of heart attack are gastrointestinal discomfort, chest pain without having typical characteristics of angina pectoris, syncope, and cough and breathlessness. It can be silent attack also in patients who are diabetic, woman, elderly, and post-operative patients.
When is 3rd heart sound typically heard ?
The third heart sound (S3), also known as the “ventricular gallop,” occurs just after S2 when the mitral valve opens, allowing passive filling of the left ventricle. The S3 sound is actually produced by the large amount of blood striking a very compliant left ventricle. It can be heard in the context of fluid overload.
When is S4 or 4th heart sound typically heard?
The fourth heart sound, S4, also known as ‘atrial gallop’ results from the contraction of the atria pushing blood into a stiff or hypertrophic ventricle, indicating failure of the left ventricle, diastolic dysfunction due to left ventricular stiffness.
What are the systemic and vital sign changes seen in heart attack ?
- Distress
- pallor
- Diaphorosis
- Tachycardia
- Supraventricular or
ventricular arrhythmia - Hypotension due to acute LVF
*
What are the respiratory and cardiovascular signs of heart attack ?
*Respiratory: lower zone crackles and pulmonary edema.
* cardiac: New murmur due to mitral regurgitation secondary to papillary muscle necrosis, S3 and or S4 gallops, JVPE due to acute CCF, Carotid bruit and loss of peripheral pulses due to cardiogenic shock.
What is the diagnostic approach to chest pain ?
- Persistant ST elevation- STEMI
- ST/ T wave abnormalities with raise and fall of troponin - NSTEMI.
- Normal or undetermined ECG with chest pain and normal troponin - unstable angina.
What is the sequence of serial ECG in chest pain ?
on arrival - 3 hrs- 6hrs looking for ST Elevation / Depression / dynamic T wave inversion / Q waves / new LBBB
What is the sequence of Serial cardiac biomarkers in patients admitted with chest pain ?
*Normal sensitivity Troponin T or I – on arrival, 6hrs, 12hrs
*High Sensitivity Troponin T or I – On arrival, 3hrs, 6hrs.
+ coronary angiography to detect obstructing plaque.