Cardiovascular System Flashcards

Which of the following hemodynamic parameters is most indicative of left ventricular preload?

Answer: Pulmonary artery wedge pressure (PAWP)

Pulmonary artery wedge pressure (PAWP), also known as pulmonary capillary wedge pressure (PCWP), is the most accurate hemodynamic parameter for estimating left ventricular preload. It reflects the pressure in the left atrium and, indirectly, the left ventricular end-diastolic pressure, which determines the stretch of the left ventricular muscle fibers before contraction. This measurement is crucial for assessing fluid status and cardiac function.

A patient is admitted with acute decompensated heart failure. Which medication class is most appropriate to reduce preload and relieve pulmonary congestion?

Answer: Loop diuretics

Loop diuretics, such as furosemide, are highly effective in acute decompensated heart failure because they promote rapid diuresis. By inhibiting sodium and chloride reabsorption in the loop of Henle, they reduce circulating blood volume. This action directly decreases preload and alleviates pulmonary congestion, which are key goals in managing acute heart failure.

Which ECG change is commonly associated with hypokalemia?

Answer: U waves

Hypokalemia, a low potassium level, commonly manifests on an ECG as the presence of U waves, which are small, positive deflections following the T wave. It can also cause flattened or inverted T waves and a prolonged QT interval. Peaked T waves, in contrast, are characteristic of hyperkalemia.

What is the most appropriate intervention for a patient in atrial fibrillation with a rapid ventricular response and signs of hemodynamic instability?

Answer: Initiate synchronized cardioversion

For a patient in atrial fibrillation with a rapid ventricular response who is hemodynamically unstable (e.g., hypotension, altered mental status), immediate synchronized cardioversion is the most appropriate intervention. This electrical therapy rapidly converts the rhythm to restore hemodynamic stability. Medications are used for rate control in stable patients, not for unstable rhythms.

A patient is post-op day 1 from coronary artery bypass graft (CABG) surgery and develops muffled heart sounds and hypotension. What complication should the nurse suspect?

Answer: Cardiac tamponade

Muffled heart sounds and hypotension in a post-CABG patient are classic signs of cardiac tamponade, a life-threatening complication where fluid accumulates in the pericardial sac. This fluid compresses the heart, impairing ventricular filling and leading to decreased cardiac output and hypotension. Other signs include jugular venous distension, forming Beck's triad.

What is the primary action of nitroglycerin when used in acute coronary syndrome (ACS)?

Answer: Dilates coronary arteries

Nitroglycerin primarily acts as a vasodilator, relaxing smooth muscle in both veins and arteries, including the coronary arteries. In acute coronary syndrome, this dilation increases blood flow to the ischemic myocardium, improving oxygen supply. It also reduces preload by venous dilation, which decreases myocardial oxygen demand.

Which of the following rhythms requires immediate defibrillation?

Answer: Ventricular fibrillation

Ventricular fibrillation (VFib) is a chaotic, life-threatening arrhythmia characterized by disorganized electrical activity in the ventricles, leading to ineffective cardiac contraction and immediate loss of consciousness. Immediate defibrillation is crucial to terminate VFib and restore a perfusing rhythm, as it is a pulseless rhythm requiring immediate electrical intervention.

In monitoring a patient with a myocardial infarction, which cardiac marker rises first?

Answer: Myoglobin

Myoglobin is one of the earliest cardiac markers to rise following myocardial injury, typically within 1-4 hours after symptom onset. While it is sensitive for muscle damage, it is not specific to cardiac muscle. Troponin I and CK-MB rise later but are more specific for myocardial damage.

Which complication is most associated with persistent ST-segment elevation following a myocardial infarction?

Answer: Ventricular aneurysm

Persistent ST-segment elevation weeks or months after a myocardial infarction, especially in the same leads, is highly suggestive of a ventricular aneurysm. This complication occurs when the infarcted myocardial wall thins and bulges outward during systole. It can lead to heart failure, arrhythmias, and thrombus formation.