An infant with congestive heart failure is receiving diuretic therapy at home. Which of the following symptoms would indicate that the dosage may need to be increased?
A. Sudden weight gain
B. Decreased blood pressure
C. Slow, shallow breathing
D. Bradycardia
Correct Answer: A. Sudden weight gain
Weight gain is an early symptom of congestive heart failure due to accumulation of fluid. Important among these are renal retention of fluid, renin-angiotensin mediated vasoconstriction and sympathetic overactivity. Excessive fluid retention increases the cardiac output by increasing the end diastolic volume (preload), but also results in symptoms of pulmonary and systemic congestion.
Option B: Vasoconstriction (increase in afterload) tends to maintain flow to vital organs, but it is disproportionately elevated in patients with CHF and increases myocardial work. Similarly, sympathetic overactivity results in increase in contractility, which also increases myocardial requirements. An understanding of the interplay of the four principal determinants of cardiac output – preload, afterload, contractility and heart rate is essential in optimising the therapy of CHF. It is clinically useful to consider CHF in different age groups separately.
Option C: In the past, the most sensitive and specific variables for the presence of CHF (p<0.0001) were, a history of less than 3.5 oz/feed, respiratory rate greater than 50/min, an abnormal respiratory pattern, diastolic filling sounds, and hepatomegaly. Moderate to severe CHF was considered to be present when patients took less than 3 oz/feed or greater than 40 min/feed, had an abnormal respiratory pattern with a resting respiratory rate greater than 60/min, and had a diastolic filling sound and moderate hepatomegaly.
Option D: Tachycardia >150/min is common, and heart rates >180/min are abnormal even in the setting of respiratory distress and suggests CHF. Severe CHF was accompanied by a heart rate greater than 170/min, decreased perfusion, and severe hepatomegaly. Thus, the grading of the severity of CHF in infants should include an accurate description of these historical and clinical variables.