Heart failure

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Heart failure

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$NOTES NOTES HEART FAILURE GENERALLY, WHAT IS IT? PATHOLOGY & CAUSES ▪ A complex clinical syndrome characterized by the heart’s inability to effectively ﬁll and/ or eject (pump) blood ▪ Stroke volume (SV): volume (mL) of blood pumped by heart per contraction ▪ Cardiac output (CO): volume of blood pumped by heart per minute (L/min) ▫ CO = SV X heart rate ▪ Preload: amount of blood in left ventricle before contraction ▪ Afterload: stress on the ventricular wall during systole ▫ ↑ systemic resistance, ↑ blood viscosity, aortic valve stenosis, ventricular dilation → ↑ afterload ▪ Inotropy: cardiac contractility ▪ Ejection fraction (EF): % of blood leaving heart during each contraction ▫E= ( stroke volume end diastolic volume ) x100 ▪ Frank–Starling mechanism: loading ventricle with blood during diastole, stretching out cardiac muscles → more forceful contraction; ↑ SV during systole Heart failure (HF) with reduced ejection fraction (HFrEF) ▪ Systolic HF; “pump dysfunction” ▪ Causes: ↓ contractility/force of contraction (e.g. myocardial infarction, myocarditis), ↓ blood supply to the heart (e.g. coronary artery disease), ↑ afterload (e.g. hypertension), impaired mechanical function (e.g. valve disease) ▪ Normal preload, ↓ contractility (inotropy; force of contraction) → inadequate emptying of ventricles during systole → ↓ EF ≤ 40 (HFrEF); often also have some degree of diastolic dysfunction HF with preserved ejection fraction (HFpEF) ▪ Diastolic HF; “ﬁlling dysfunction” ▪ Causes: restrictive cardiomyopathy (e.g. amyloidosis, sarcoidosis), valve disease, hypertension ▪ Ventricles noncompliant and unable to ﬁll during diastole → ↑ ﬁlling pressures ↓ preload, normal contractility → ↓ SV → preserved EF ≥ 50 (HFpEF) TYPES ▪ Biventricular heart failure ▫ Left, right failure; systolic/diastolic ▪ Cor pulmonale ▫ Heart failure secondary to any cause of pulmonary arterial hypertension ▪ Left-sided heart failure ▫ Impaired ability of the left ventricle to maintain adequate cardiac output without an increase in left-sided ﬁlling pressures ▪ Right-sided heart failure ▫ Impaired ability of the right ventricle to deliver of blood ﬂow to the pulmonary circulation and ↑ right atrial pressure ▪ Classiﬁcation based on structure and symptoms ▫ ACC/AHA HF Stages, NYHA Classes (see table) OSMOSIS.ORG 55$

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Heart failure

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A previously healthy one-month-old infant is admitted to the hospital because of respiratory distress. He was born at term following an uncomplicated pregnancy and delivery. He had been well until 2 days ago when he developed fever and malaise. His pulse is 162/min, respirations are 54/min, and blood pressure is 64/48 mm Hg. Examination shows evidence of heart failure. A viral infection is suspected as the etiology of his acute heart failure. Which of the following is the most likely causal virus?

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