Learning Cardiology

  Basic principles of the ECG Voltage and timing intervals 1mV is represented by a deflection of 10 mm Each small square represents 40 milliseconds (ms) 5 small squares, thus representing 200 ms. Heart rate estimation HR = 300/ Number of large boxes between two RR waves If the number of large boxes: 5 - the HR is 60 beats per minute. 3 - the HR is 100 per minute. 2 - the HR is 150 per minute. Normal heart rate = between 60 to 100 beats per minute Electrical axis The overall direction of travel of the electrical depolarization wave through the heart is known as the electrical axis. Limb leads record ECG in the coronal plane, hence used to determine the electrical axis. The limb leads are I, II, III, AVR, AVL and AVF. The cardiac electrical axis is normally downward and to the left. The electrical axis is expressed in degrees and is normally in the range from -30 to + 90 degrees. Normal ECG P wave Depolarization of atria during sinus rhythm generates P wave  PR interval  Short physiologi

 Q. Mavacamten was recently assessed and found to be useful in which of the following disease? A. DCMP B. HOCM C. Coronary artery disease with mitral regurgitation D. Amyloidosis Answer: B. HOCM Mavacamten is a medication that relaxes the heart muscle and treats obstructive hypertrophic cardiomyopathy (HCM). It is a small-molecule inhibitor of cardiac myosin that reduces myocardial contractility and improves myocardial energetics.

Q. Which of the following represents a normal HV interval during cardiac electrophysiological testing? A. <20 ms B. 35-55 ms C. 100-125 ms D. >200 ms Correct Answer: B. 35-55 ms Explanation:  https://www.learningcardiology.com/2020/07/normal-cardiac-electrophysiology.html

Important intervals in cardiac electrophysiology 1. PA interval: 25-55 ms 2. AH interval: 55-125 ms 3. HBE interval: <30 ms 4. HV interval: 35-55 ms 5. QRS: ≤ 100 ms 6. Corrected QT interval (QTc): ≤ 450 ms (for males); ≤ 470 ms (for females) 7. Sinus node recovery time (SNRT): ≤1500 ms 8. Corrected sinus node recovery time (CSNRT): ≤ 550 ms 9. Sinoatrial conduction time (SACT): 50-115 ms 10. Atrial effective refractory period (ERP): 180-330 ms 11. AV nodal ERP: 250-400 ms 12. Ventricular ERP: 180-290 ms

Q. What will be class of the following LM bifurcation disease as per the newly proposed ABCD classification system? A. ABC B. ABc C. Ab D. BC Correct answer: B. ABc Explanation:  ABCD classification for LM bifurcation

A new classification system for LM bifurcation/ trifurcation lesions has been proposed.  1. Following nomenclature has been suggested:       A/a for LM coronary artery      B/b for LAD artery      C/c for left circumflex coronary artery      D/d for ramus intermedius artery (intermediate branch) Whether a capital or small letter would be used, depends upon the diameter of the vessel as explained below.  2. Each artery is given one of the above-mentioned letters if the stenosis is considered to be significant (i.e., >70% in lumen reduction visually,  or based on FFR or other resting indices, cCT-cFFR, IVUS, OCT). 3. If the stenosis is not considered significant, no letter would be assigned. 4. A capital letter is used if the vessel diameter is ≥3.5 mm, while a small letter is used if the diameter is smaller than 3.5.  5. The image below has significant stenosis in all three vessels i.e LM, LAD and LCx. LM and LAD arteries are more than 3.5 mm in diameter, whereas LCx is smaller than

Q. Which of the following is not true regarding the ISCHEMIA trial ? A. Patients with stable angina were included B. The patients with LM disease were excluded with a CT angiogram C. Early invasive therapy was found to reduce MI and cardiovascular mortality compared to medical therapy in patients with stable angina D. Results are not applicable to patients with severe LV dysfunction Correct answer: C. Early invasive therapy was found to reduce MI and cardiovascular mortality compared to medical therapy in patients with stable angina Explanation: https://www.learningcardiology.com/2020/06/ischemia-trial.html

Background: We don't know the optimum mode of therapy for patients with stable ischemic heart disease along with moderate to severe myocardial ischemia on non-invasive stress testing. Routine early invasive therapy was compared with optimal medical therapy in this trial. Study design: Patients: Stable ischemic heart disease with moderate to severe ischemia on stress testing. All patients underwent CT coronary angiogram prior to inclusion in the trial to rule out significant LM disease. Exclusion: - LM stenosis >50% (on CT coronary angiogram) - Recent MI - LVEF < 35% - Unacceptable angina at baseline - NYHA class III and IV heart failure - Prior PCI or CABG within last one year Groups: Routine invasive therapy (n = 2588) vs initial optimal medical therapy (n= 2591) Interventions in both groups: - Routine invasive group: Patients underwent angiography followed by PCI or CABG as per the anatomy. - Medical therapy group: All patients were put on initial medi