WBR0438
| Author | [[PageAuthor::Rim Halaby, M.D. [1]]] |
|---|---|
| Exam Type | ExamType::USMLE Step 1 |
| Main Category | MainCategory::Physiology |
| Sub Category | SubCategory::Cardiology |
| Prompt | [[Prompt::A 73 year old patient with hypertension presents to the emergency department for dyspnea at rest. Following appropriate evaluation, the patient is diagnosed with heart failure. The physician explains to the patient that his ventricles are not appropriately relaxing and filling. Which phase on electrocardiography (ECG) scheme shown below represents ventricular relaxing and filling?
|
| Answer A | AnswerA::PR segment |
| Answer A Explanation | AnswerAExp::PR segment reflects AV nodal delay. |
| Answer B | AnswerB::ST segment |
| Answer B Explanation | AnswerBExp::ST segment reflects the time during which ventricles contract. |
| Answer C | AnswerC::QRS complex |
| Answer C Explanation | AnswerCExp::QRS complex reflects ventricular depolarization and simultaneous atrial repolarization. |
| Answer D | AnswerD::QT interval |
| Answer D Explanation | AnswerDExp::QT interval reflects total duration of ventricular depolarization and repolarization. |
| Answer E | AnswerE::TP interval |
| Answer E Explanation | AnswerEExp::TP interval reflects ventricular relaxation and refilling. |
| Right Answer | RightAnswer::E |
| Explanation | [[Explanation::The waves on ECG reflects depolarization and repolarization effects; whereas baseline reflects when there is no net depolarization or repolarization, such as in cases of muscular rest or contraction. On ECG, P wave reflects atrial depolarization, PR segment reflects AV nodal delay, QRS complex reflects ventricular depolarization and simultaneous atrial repolarization, ST segment reflects time during which ventricular contraction is occurring, T wave reflects ventricular repolarization, and TP interval reflects the time during which ventricles relax and refill.
Educational Objective: On ECG, TP interval reflects the time during which ventricles relax and refill. Reference:
Berne RM. Cardiovascular physiology. Annu. Rev. Physiol. 1981;43:357-358 |
| Approved | Approved::No |
| Keyword | WBRKeyword::ECG, WBRKeyword::electrocardiogram, WBRKeyword::ventricle, WBRKeyword::filling, WBRKeyword::relaxation, WBRKeyword::wave, WBRKeyword::repolarization |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |
