CMC Technology & Digital Tools 5 — Questions and Answers
Question 1: In the cardiac catheterization laboratory, radiation dose is most effectively reduced by which operator-controlled technique?
- Maximizing distance from the X-ray source and using collimation to limit beam field size (Correct answer)
- Increasing frame rate to 30 frames per second for clearer images
- Using magnification mode to improve lesion visualization
- Keeping the image intensifier as far from the patient as possible
Correct answer: Maximizing distance from the X-ray source and using collimation to limit beam field size
Distance (inverse square law) and collimation are the most effective operator-controlled methods to reduce scatter radiation exposure.
Question 2: A subcutaneous implantable cardioverter-defibrillator (S-ICD) is contraindicated in patients who:
- Require chronic cardiac pacing or antitachycardia pacing for ventricular tachycardia termination (Correct answer)
- Have had a prior transvenous ICD that was extracted
- Weigh more than 100 kg due to sensing issues
- Have preserved ejection fraction above 35%
Correct answer: Require chronic cardiac pacing or antitachycardia pacing for ventricular tachycardia termination
The S-ICD lacks transvenous leads and cannot provide bradycardia pacing or antitachycardia pacing, making it unsuitable for patients requiring these functions.
Question 3: Which cardiac imaging modality uses radioactive tracers to assess myocardial perfusion and is considered the gold standard for detecting viable but hibernating myocardium?
- Positron emission tomography (PET) with F-18 fluorodeoxyglucose (FDG) (Correct answer)
- Single-photon emission computed tomography (SPECT) with Tc-99m sestamibi
- Cardiac MRI with gadolinium late enhancement
- Dobutamine stress echocardiography
Correct answer: Positron emission tomography (PET) with F-18 fluorodeoxyglucose (FDG)
FDG-PET identifies viable hibernating myocardium by demonstrating preserved glucose metabolism in segments with reduced perfusion (perfusion-metabolism mismatch).
Question 4: When programming an ICD for a patient with hypertrophic cardiomyopathy, which programming strategy reduces inappropriate shocks from T-wave oversensing?
- Adjusting ventricular sensing threshold and enabling wavelet-based T-wave discrimination algorithms (Correct answer)
- Increasing the VF detection zone rate to 200 bpm
- Programming the device to VVI mode only
- Disabling all anti-tachycardia pacing therapies
Correct answer: Adjusting ventricular sensing threshold and enabling wavelet-based T-wave discrimination algorithms
T-wave oversensing is common in HCM due to tall T-waves; adjusting sensitivity and enabling morphology-based discrimination reduces inappropriate therapy.
Question 5: In a hospital's cardiac care unit, an electronic health record (EHR) clinical decision support alert fires when a nurse enters a QTc of 520 ms. This alert MOST appropriately prompts review of:
- All QT-prolonging medications, electrolytes (K+, Mg2+), and consideration of telemetry monitoring for TdP (Correct answer)
- Immediate cardioversion protocol for atrial fibrillation
- Pacemaker interrogation for upper rate limit programming
- Cardiac biomarkers for acute myocardial infarction workup
Correct answer: All QT-prolonging medications, electrolytes (K+, Mg2+), and consideration of telemetry monitoring for TdP
QTc ≥500 ms significantly increases risk of torsades de pointes; the priority is identifying and removing QT-prolonging drugs and correcting electrolyte deficiencies.
Question 6: Intracardiac echocardiography (ICE) used during electrophysiology procedures provides which advantage over transesophageal echocardiography?
- Eliminates the need for general anesthesia or deep sedation while providing real-time intracardiac visualization (Correct answer)
- Provides superior resolution of pulmonary veins compared to TEE
- Allows simultaneous 3D reconstruction of all cardiac chambers
- Reduces overall procedure cost due to reusable probe design
Correct answer: Eliminates the need for general anesthesia or deep sedation while providing real-time intracardiac visualization
ICE catheters are advanced via femoral vein and allow high-quality cardiac imaging without requiring general anesthesia, enabling conscious sedation EP procedures.
Question 7: A patient's continuous glucose monitoring (CGM) data integrated into the cardiac EHR shows recurrent nocturnal hypoglycemia with simultaneous heart rate variability (HRV) changes. This finding is MOST relevant to which cardiac condition?
- Increased risk of nocturnal arrhythmias and sudden cardiac death in diabetic patients with autonomic neuropathy (Correct answer)
- Worsening heart failure requiring diuretic adjustment
- Unstable angina triggered by hypoglycemia-induced coronary spasm
- Atrial fibrillation onset related to sympathetic activation
Correct answer: Increased risk of nocturnal arrhythmias and sudden cardiac death in diabetic patients with autonomic neuropathy
Nocturnal hypoglycemia causes QT prolongation and autonomic instability, increasing arrhythmia risk in diabetic patients with cardiac autonomic neuropathy.
CMC Technology & Digital Tools 5
In the cardiac catheterization laboratory, radiation dose is most effectively reduced by which operator-controlled technique?