| Snapshot |
| A 15-year-old boy presents to the emergency room after collapsing on the basketball court. His mom reports that he has been pushing himself physically to do well in basketball. She states that he has had several episodes of syncope while playing basketball. There is also a family history of sudden cardiac death in several relatives. On physical exam, the boy has an S4 heart sound and a systolic murmur. (Hypertrophic cardiomyopathy) |
| Introduction |
| The cardiac cycle is divided into 7 components Atrial systole (1) atria contractthis is the final phase of ventricular fillingelectrocardiogram (ECG) findingP wavefinal phase of ventricular fillingECG findingPR intervalIsovolumetric contraction (2)period from between mitral valve closure to aortic valve openingventricles contract and pressure increasesECG findingQRS complexpressure is constant, as all the valves are closedperiod of highest O2 consumptionSystolic ejectionperiod from aortic valve opening to aortic valve closingtwo phasesrapid ejection (3)ventricles contracts and pumps blood into arteriesventricular pressure reaches maximumECG findingST segmentreduced ejection (4)ventricles pump blood at a slower rateventricular volume is at its minimumECG findingT waveIsovolumetric relaxation (5)period from aortic valve closure to mitral valve openingventricles relax with no fillingRapid ventricular filling (6)period right after mitral valve opensReduced ventricular filling, or diastasis (7)period right before mitral valve closes |
| Heart Sounds |
| S1 closure of the mitral and tricuspid valvesloudest at mitral areaS2closure of aortic and pulmonary valvesloudest at left upper sternal borderS3 early diastoleassociated with ↑ filling pressuresmitral regurgitationcongestive heart failuredilated ventriclesnormal in children and pregnancyS4late diastolealso referred to as “atrial kick”loudest at apex with the patient in left lateral decubitus positionassociated with ↑ atrial pressure and ventricular hypertrophy left atrium pushes against a stiff and noncompliant left ventricular wallalways abnormal |
| Jugular Venous Pulse (JVP) |
| a wave atrial contractionabsent inatrial fibrillationc waveright ventricular contractiontricuspid valve is closed and bulges into atriumx descenttricuspid valve is closed and is displaced downward during rapid ejection phasereduced or absent intricuspid regurgitationright heart failurev wave↑ right atrial filling pressures against closed tricuspid valvey descentright atrium empties into right ventricleincreased inconstrictive pericarditisabsent incardiac tamponade |
