A nurse is providing discharge instructions to the parent of a 10yearold child following a cardiac catheterization. Which of the following instructions should the nurse include?

A. "Coronary arteries decrease in diameter leading to insufficient blood, oxygen, and nutrients reaching the heart muscle." Coronary artery disease (CAD) is characterized by atherosclerosis, where plaque buildup narrows the coronary arteries, reducing blood flow. This leads to myocardial ischemia, causing symptoms such as angina, shortness of breath, and fatigue due to inadequate oxygen supply to the myocardium.
B. "Manifestations occur due to dilation of coronary arteries with increased blood flow causing increased pressure." CAD does not result from arterial dilation but rather from progressive narrowing and reduced perfusion. Increased blood flow does not cause symptoms; instead, decreased perfusion leads to myocardial hypoxia and ischemic symptoms.
C. "Coronary arteries become more elastic causing the arteries to stretch as individuals age causing the heart not to receive enough oxygen." Aging can affect arterial compliance, but CAD is primarily caused by atherosclerosis, which makes the arteries stiff and narrow rather than more elastic. The problem is restricted blood flow, not excessive elasticity.
D. "The heart and the coronary arteries weaken, leading to poor perfusion and resulting in angina." While CAD can lead to heart failure and reduced cardiac output, the primary mechanism is arterial narrowing due to plaque accumulation, which limits blood supply and oxygen to the myocardium, triggering angina.

A. Chest xray. A chest xray may show an enlarged cardiac silhouette ("water bottle heart") due to the accumulation of pericardial fluid, but it is not the most immediate or definitive diagnostic tool for cardiac tamponade.
B. Echocardiogram. An echocardiogram is the firstline diagnostic test for suspected cardiac tamponade. It provides realtime imaging of the heart, allowing visualization of pericardial effusion, right ventricular collapse during diastole, and impaired cardiac filling, which are hallmark signs of tamponade. It is noninvasive, rapid, and highly sensitive, making it the preferred initial test.
C. Computed tomography (CT) scan. A CT scan can detect pericardial effusion, but it is not the first choice due to longer imaging time and lower practicality in an emergent setting. It is often used when echocardiography is inconclusive or when other mediastinal pathology is suspected.
D. Electrocardiogram (ECG). An ECG in tamponade may show low voltage QRS complexes, electrical alternans, or nonspecific ST changes, but these findings are not definitive. ECG cannot directly visualize pericardial fluid or hemodynamic compromise, making it less useful than echocardiography for confirming the diagnosis.