Learning Cardiology

  a wave and v wave roughly correspond to P wave and QRS complex in electrocardiogram respectively.  a wave falls on S1 and v falls on S2. Hence, in sinus rhythm a wave is preceded by v wave .  In 1st degree heart block, a wave (P) will occur much before S1 (onset of ventricular systole) and denotes a prolonged PR interval. And, with further prolongation, a wave may merge with previous  v wave .   In 2nd degree type 1 AV block, there will gradual prolongation of a-v interval in JVP ending with a wave which is not followed by v wave .  In 2:1 AV block, there will be two a waves for each v wave . Alternate a wave will coincide with ventricular systole resulting in regular cannon a waves .  In complete heart block, a-v interval is variable with a more than v waves along with irregular cannon a waves . Irregular cannon a waves will be seen whenever a wave coincides with ventricular systole because of AV dissociation in CHB.  Irregular cannon a waves may also be seen during

Q. Which of the following formula is not used for estimation of LDL? A. Friedwald B. Sampson C. Martin/Hopkins D. Bazett Correct answer: D. Bazett Bazett's formula is used for estimation of corrected QT interval on ECG. Whereas, other three formulas Friedwald, Sampson and Martin/Hopkins are used for low density cholesterol (LDL) estimation in blood. 

  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