Cardiology Week 7 Scq Study Guide Questions

CARDIOLOGY WEEK 7 Saq STUDY GUIDE QUESTIONS 1. Contrast the difference between the meanings of a narrow and a wide QRS complexes. Answer: • A narrow QRS complex this is a normal QRS complex in which it is less than 3 small boxes wide. When there is an increase in heart rate, where the heart rate is above 100 bpm but then QRS complex is narrow, this suggests a supraventricular tachycardia, where the rhythm is wither starting from the SA or AV nodes, at an abnormally high speed. P waves may or may not be present. A wide QRS complex this is when the QRS complex is more than three small boxes wide. This indicates that the cause of the arrythmia are the ventricles not the atria. This indicates that the ventricles are generating the rhythm of the heart, at a rate that is higher than what the SA node would do in a healthy patient. There are NO visible P waves in such patients. • 2. a. Compare the differences in ECG presentation of a person who is NOT relaxed to a person who is relaxed. In your answer, comment of which lead is most likely to show the changes. b. How might the ECG of a person who is shivering look like? c. Show the differences in ECG readings of the different types of heart block. Answer: a. The ECG of a person who is not relaxed, will have no clear baseline like the ECG of a person who is relaxed. Rather, that clear baseline, will be replaced by sharp irregular spikes, especially within the limb leads. b. The ECG of a person, who is shivering will show sharper spikes. c. • First degree heart block: Every depolarisation from the P wave will pass onto a QRS complex. However, this happens slowly, there is a prolonged PR interval of more than 200 (i.e. more than 5 small boxes). • Second degree heart block: - I- Progression prolongation of the PR interval, until there is a drop in the QRS complex. - II – constant PR interval, but then there is a dropped QRS complex. • Third degree heart block: - No association between the P wave and the QRS complex. 3. In chronological order explain the complications that can occur post-MI. Answer: • - 0 to 24 hours: sudden cardiac death: this happens because the infarcted tissue has increased permeability -> allows cations to come into the cells in large numbers -> this causes intense arrythmias, that may cause cardiac death. Another complication that can happen within 0 to 24 hours post-MI is acute heart failure, especially if the infarct occupies a significant portion of the myocardium. • 24 hours to 3 days: the infarction causes inflammation which causes immune cells namely neutrophils and macrophages and another white blood cells to come to the area, to clear up the infarcted tissue. However, the presence of the immune cells causes inflammation that leads to pericarditis, which leads to chest pain, friction rub and pericardial effusion. 3 to 14 days: Post MI rupture: this happens because the infarcted tissue is weak and is covered by granulation tissue, which is very weak, that is susceptible to rupture. If is ruptures this will cause blood from the ventricle to leak into the pericardial cavity and thus cause a tamponade. In rupture if the region where the papillary muscles is affected, this could lead the papillary muscles to rupture and thus cause mitral valve regurgitation. 14 days to months: this is because the fibrous and granulation tissue are weak it could balloon out and cause an aneurysm to develop. Another possible complication is Dressler Syndrome. This happens because the infarction by some unknown mechanism causes an autoimmune reaction, where there will be antibodies produces against the myocardium and thus cause pericarditis. • • 4. What are the causes of cardiogenic syncope? Answer: • Arrythmia related: the heart rate becomes too fast for the heart to fully fill and thus a diastolic failure. There can also be a systolic failure, because if the heart beats to fast, then it will not have enough time to fully eject all of the blood out. • Mechanical: - Due to decreased contractility such that there is a heart failure with a reduced ejection fraction. For example, MI. - Decreased filling of the heart: for example, when there is an obstructive hypertrophy, tamponade, tension pneumothorax. - Increase in afterload: systemic hypertension, aortic valve stenosis, pulmonary embolism etc.