CCI - Cardiovascular Credentialing International Cardiac Anatomy and Physiology Questions and Answers — Questions and Answers
Question 1: A patient is diagnosed with mitral valve prolapse. Which of the following structures are primarily responsible for preventing the eversion of the atrioventricular (AV) valve leaflets into the atria during ventricular systole?
- Aortic sinuses
- Papillary muscles and chordae tendineae (Correct answer)
- Thebesian veins
- Crista terminalis
Correct answer: Papillary muscles and chordae tendineae
The chordae tendineae, often called 'heart strings,' are fibrous cords that connect the leaflets of the atrioventricular valves (mitral and tricuspid) to the papillary muscles of the ventricles. During ventricular contraction (systole), the papillary muscles contract, which tenses the chordae tendineae and prevents the valve leaflets from being pushed back (everting) into the atria under high pressure.
Question 2: Which of the following correctly describes the Frank-Starling mechanism of the heart?
- Increased heart rate leads to a proportional increase in stroke volume.
- The force of ventricular contraction is independent of the end-diastolic volume.
- Increased stretch of the ventricular myocardium leads to a more forceful contraction. (Correct answer)
- Hormonal stimulation is required to match cardiac output to venous return.
Correct answer: Increased stretch of the ventricular myocardium leads to a more forceful contraction.
The Frank-Starling law states that the stroke volume of the heart increases in response to an increase in the volume of blood filling the ventricles (the end-diastolic volume). When a larger volume of blood stretches the ventricular muscle fibers, it leads to a more forceful contraction, thereby increasing the stroke volume. This is an intrinsic property of the heart muscle.
Question 3: A blockage in the posterior descending artery (PDA) would most likely cause ischemia in which area of the heart, assuming a right-dominant coronary circulation?
- Anterolateral wall of the left ventricle
- Anterior two-thirds of the interventricular septum
- Inferior wall of the left ventricle and posterior one-third of the interventricular septum (Correct answer)
- Lateral wall of the right atrium
Correct answer: Inferior wall of the left ventricle and posterior one-third of the interventricular septum
In a right-dominant circulation, which is the most common pattern (~80% of individuals), the posterior descending artery (PDA) arises from the right coronary artery (RCA). The PDA supplies blood to the inferior wall of the left ventricle and the posterior one-third of the interventricular septum. Therefore, an occlusion of the PDA would cause ischemia in these specific territories.
Question 4: What is the correct sequence of electrical impulse conduction through the heart?
- AV node -> SA node -> Bundle of His -> Purkinje fibers
- Bundle of His -> Purkinje fibers -> SA node -> AV node
- SA node -> AV node -> Bundle of His -> Bundle branches -> Purkinje fibers (Correct answer)
- Purkinje fibers -> Bundle branches -> Bundle of His -> AV node -> SA node
Correct answer: SA node -> AV node -> Bundle of His -> Bundle branches -> Purkinje fibers
The normal cardiac conduction pathway begins with an impulse generated by the sinoatrial (SA) node, the heart's natural pacemaker. The impulse then travels to the atrioventricular (AV) node, where it is briefly delayed. From the AV node, it proceeds to the Bundle of His, divides into the right and left bundle branches, and finally spreads through the Purkinje fibers to cause ventricular contraction.
Question 5: Which layer of the heart wall is the thickest and composed primarily of cardiac muscle responsible for the heart's pumping action?
- Endocardium
- Pericardium
- Epicardium
- Myocardium (Correct answer)
Correct answer: Myocardium
The heart wall consists of three layers: the inner endocardium, the middle myocardium, and the outer epicardium. The myocardium is the muscular middle layer and is the thickest of the three. Its powerful contractions are responsible for pumping blood out of the heart. The thickness of the myocardium varies, being thickest in the left ventricle.
Question 6: A patient undergoes an echocardiogram which reveals blood flowing from the left ventricle back into the left atrium during systole. This finding indicates a failure of which valve to close properly?
- Aortic valve
- Tricuspid valve
- Mitral valve (Correct answer)
- Pulmonary valve
Correct answer: Mitral valve
The mitral valve (also known as the bicuspid valve) is located between the left atrium and the left ventricle. Its function is to prevent the backflow of blood into the left atrium when the left ventricle contracts (systole). Regurgitation, or backflow, from the left ventricle to the left atrium during systole is a clear sign of mitral valve insufficiency or failure to close completely.
CCI - Cardiovascular Credentialing International Cardiac Anatomy and Physiology Questions and Answers
A patient is diagnosed with mitral valve prolapse.
Which of the following structures are primarily responsible for preventing the eversion of the atrioventricular (AV) valve leaflets into the atria during ventricular systole?