Preload & Afterload in Cardiac Function and Heart Failure

What is preload in the context of cardiac function?

The amount of blood returning to the heart before contraction, influencing end-diastolic volume (EDV).

How does preload affect stroke volume?

Increased preload leads to stronger contractions, enhancing stroke volume.

What can excessive preload cause in the heart?

Overstretching of the myocardium, reducing contractility and potentially leading to heart failure.

What is afterload?

The resistance the heart must overcome to eject blood during systole.

What factors influence afterload?

Systemic vascular resistance (SVR), blood pressure, and aortic valve condition.

How does high afterload affect myocardial workload?

It increases myocardial oxygen demand and can lead to ventricular hypertrophy over time.

What are common causes of increased preload?

Fluid overload, valvular regurgitation, and dilated cardiomyopathy.

What is the effect of excess preload on heart failure?

It can lead to ventricular dilation and weakened contractions, causing systolic heart failure (HFrEF).

What are common causes of increased afterload?

Hypertension, aortic stenosis, and pulmonary hypertension.

What is the relationship between afterload and heart failure?

High afterload leads to concentric hypertrophy, diastolic dysfunction, and eventually systolic failure.

What does an inferior vena cava (IVC) assessment indicate about preload?

IVC diameter and collapsibility can indicate fluid overload or hypovolemia.

What does an increased left ventricular end-diastolic volume (LVEDV) indicate?

High preload.

What does a decreased LVEDV suggest?

Low preload, indicating hypovolemia or poor filling.

How is pulmonary venous flow used in assessing preload?

Abnormal pulmonary venous flow indicates high preload and left atrial pressure.

What is the significance of left ventricular hypertrophy (LVH) in assessing afterload?

Increased wall thickness indicates chronic high afterload.

What measurements indicate severe aortic stenosis?

Peak velocity >4 m/s and mean gradient >40 mmHg.

What does elevated systemic vascular resistance (SVR) indicate?

Increased afterload, often due to hypertension or vasoconstriction.

What is the left ventricular ejection fraction (LVEF) threshold for systolic heart failure?

LVEF <40% indicates systolic heart failure (HFrEF).

What E/e' ratio indicates elevated left atrial pressure?

E/e' >15 suggests diastolic heart failure.

What does a tricuspid regurgitation velocity >2.8 m/s suggest?

Pulmonary hypertension, often associated with right heart failure.

What is the global longitudinal strain (GLS) threshold for normal function?

GLS <-18% is considered normal.

What does TAPSE <1.6 cm indicate?

Right ventricular dysfunction.

What is McConnell's Sign?

Apical sparing of right ventricular contraction, indicating acute pulmonary embolism.