AN22.1-7 | Heart & Pericardium — Gate Quiz

Correct! The pericardial cavity lies between the parietal layer of serous pericardium (inner layer of the fibrous pericardium) and the visceral layer of serous pericardium (epicardium, on the heart surface). It normally contains 20–50 mL of serous fluid for lubrication.

Pericardium layers: Fibrous pericardium (outer, tough, inelastic) → Parietal serous pericardium (lines inside of fibrous) → Pericardial cavity (20–50 mL fluid) → Visceral serous pericardium = epicardium (on heart surface). Cardiac tamponade: fluid in pericardial cavity (>150–200 mL) compresses the heart. Beck's triad: hypotension + raised JVP + muffled heart sounds.

Incorrect. Pericardial cavity = between parietal serous pericardium and visceral serous pericardium (epicardium). The fibrous pericardium is the outer tough layer.

Correct! Beck's triad for cardiac tamponade: (1) Hypotension (reduced cardiac output from external compression), (2) Raised JVP (elevated venous pressure due to obstructed venous return), (3) Muffled heart sounds (fluid around heart dampens sounds). Emergency treatment: pericardiocentesis.

Cardiac tamponade: Fluid in pericardial cavity (rapidly accumulated even 200 mL can be fatal due to inelastic fibrous pericardium). Beck's triad: Hypotension + JVP ↑ + Muffled heart sounds. ECG: electrical alternans (QRS varying in amplitude), sinus tachycardia. CXR: globular heart shadow. Kussmaul's sign: JVP rises on inspiration (paradox).

Incorrect. Beck's triad: Hypotension + raised JVP + muffled heart sounds = cardiac tamponade. The fibrous pericardium is inelastic; rapidly accumulated fluid compresses the heart.

Correct! The sternocostal (anterior) surface of the heart is predominantly formed by the right ventricle. The right ventricle is the most anteriorly placed chamber, directly behind the sternum and costal cartilages. This is why right ventricular injuries are most common in penetrating chest injuries.

Heart surfaces: Sternocostal (anterior) — mainly right ventricle. Diaphragmatic (inferior) — mainly left ventricle + right ventricle. Posterior (base) — mainly left atrium. Pulmonary (left lateral) — mainly left ventricle. Right margin — right atrium. Left margin — left ventricle + left auricle.

Incorrect. Anterior surface = predominantly right ventricle. The right ventricle forms about 2/3 of the anterior surface; the remaining 1/3 is the right atrium (on the right) and the left ventricle (on the left edge).

Correct! Coronary dominance is defined by which artery gives rise to the posterior interventricular (posterior descending) artery. In approximately 70% of people, the RCA supplies the posterior interventricular artery — this is right dominant. In ~10–15%, the left circumflex artery supplies it (left dominant). In ~15%, both contribute (co-dominant).

Coronary arteries: Left main → LAD (anterior IV branch, most commonly occluded in MI) + Left circumflex. RCA → right marginal + posterior IV artery (in right-dominant individuals). Right dominance: ~70%. Left dominance: ~10–15%. Co-dominant: ~15%. LAD occlusion: anterior wall MI + anterior septal infarct + LV dysfunction.

Incorrect. Coronary dominance = which artery gives the posterior interventricular artery. Right dominant (most common, 70%): RCA. Left dominant (10–15%): left circumflex. Co-dominant: both.

Correct! The mitral (bicuspid) valve is best auscultated at the cardiac apex — the 5th intercostal space in the midclavicular line. Murmurs from the mitral valve are transmitted towards the apex. The mitral valve anatomically lies behind the sternum at the 4th costal cartilage.

Valve auscultation areas (APMT): Aortic — 2nd right ICS, sternal border. Pulmonary — 2nd left ICS, sternal border. Mitral — 5th ICS, MCL (apex). Tricuspid — 4th left ICS, lower sternal border (or left lower sternal border). Mnemonic: 'All People Make Music.'

Incorrect. Mitral valve auscultation area: apex (5th ICS, midclavicular line). Aortic: 2nd right ICS. Pulmonary: 2nd left ICS. Tricuspid: 4th left ICS, lower sternal border.

Correct! The sinoatrial (SA) node is located in the superior part of the right atrium, just below the opening of the superior vena cava (near the junction of the SVC and right atrium, in the sulcus terminalis). It is supplied by the SA nodal artery (from RCA in ~60%, left circumflex in ~40%).

Conducting system: SA node (pacemaker, 60–100 bpm) → internodal pathways → AV node (slows conduction, 40–60 bpm) → Bundle of His → Left + Right bundle branches → Purkinje fibres → ventricular myocardium. SA node location: sulcus terminalis at SVC-RA junction. Blood supply: SA nodal artery (RCA ~60%; LCx ~40%).

Incorrect. SA node: superior right atrium, near SVC opening. AV node: interatrial septum, near coronary sinus. The Bundle of His: interventricular septum.

Correct! On a PA chest X-ray, the right heart border is formed superiorly by the superior vena cava (SVC) and inferiorly by the right atrium. The right ventricle does not form the right border — it faces anteriorly but does not extend to the right silhouette.

Heart borders on PA CXR: Right border: SVC (upper) + Right atrium (lower). Left border: Aortic knuckle + Pulmonary trunk/left PA + Left auricle + Left ventricle (lower). Superior: Aortic arch. Inferior: left ventricle + RV. Cardiothoracic ratio: >0.5 = cardiomegaly.

Incorrect. Right border on CXR: SVC (upper) + Right atrium (lower). Left border: aortic knuckle + pulmonary trunk + left auricle + left ventricle. Right ventricle forms the anterior surface, not the right border.

Correct! The most common type of ASD (secundum ASD, ~70%) is located at the fossa ovalis, the remnant of the foramen ovale in the central part of the atrial septum. Primum ASD is at the lower septum near the AV valves (associated with Down syndrome).

ASD types: Secundum (70%) — fossa ovalis. Primum (15–20%) — lower septum, endocardial cushion defect, often associated with cleft mitral valve, Down syndrome. Sinus venosus (10%) — near SVC. Coronary sinus type (rare). Fossa ovalis = remnant of the foramen ovale; patent foramen ovale (PFO) is present in 25% of adults.

Incorrect. Secundum ASD: fossa ovalis (central atrial septum). Primum ASD: lower septum near AV valves (endocardial cushion defect, associated with Down syndrome). Sinus venosus ASD: near SVC (~10%).

Correct! The inferior wall of the heart is supplied by the posterior interventricular artery — which in right-dominant individuals (70%) arises from the RCA. ST elevation in leads II, III, aVF = inferior MI = RCA occlusion in most patients.

Coronary territory ECG correlation: LAD occlusion → anterior MI (V1–V4, poor R progression). RCA occlusion → inferior MI (II, III, aVF). Left circumflex → lateral MI (I, aVL, V5, V6). RCA occlusion may also cause right ventricular MI (elevated right-sided leads). Inferoposterior MI: check ST depression in V1–V2 (reciprocal changes).

Incorrect. Inferior MI (ST elevation in II, III, aVF) = RCA territory. LAD = anterior MI (V1–V4). Circumflex = lateral MI (I, aVL, V5, V6). Diagonal = anterolateral.

Correct! The standard subxiphoid (parasternal) approach for pericardiocentesis inserts the needle just below and to the left of the xiphoid process, angling it at 45° toward the left shoulder. This avoids the pleura, lungs, and major coronary vessels. ECG-guided (ST changes indicate needle touching the epicardium).

Pericardiocentesis technique: Subxiphoid approach — needle inserted below and left of xiphoid, angled at 45° toward left shoulder. This traverses: skin → subcutaneous tissue → diaphragm (bare area) → fibrous pericardium → parietal serous pericardium → pericardial cavity. ECG monitoring: ST elevation = epicardial touch → withdraw slightly.

Incorrect. Pericardiocentesis: subxiphoid approach — below and left of the xiphoid process, needle directed 45° toward the left shoulder. Avoids lungs and major vessels.