16 Implications of Pediatric Renal, Endocrine, and Oncologic Disease

Brandy Hattendorf

Pediatric diseases of many different etiologies have cardiovascular implications. Those associated with renal, endocrine, and oncologic processes can directly or indirectly impact the cardiovascular system.

Renal

The cardiovascular complications of renal disease differ based on the etiology of the kidney disease. Cardiovascular morbidity and mortality continue to increase in association with renal disease. The most common renal diseases with cardiovascular effects include hypertension, glomerulonephritis, chronic renal failure, post-renal transplantation, and iron overload secondary to renal failure with hemodialysis.

Hypertension

• Arterial hypertension may reflect chronic kidney disease.

• Metabolic and hormonal factors in chronic renal disease contribute to the development of both hypertension and left ventricular hypertrophy (LVH).

• Hypertension is associated with LVH.

• Concentric hypertrophy is more common than eccentric hypertrophy.

• Volume overload contributes to hypertension in hemodialysis patients.

• LVH is an independent risk factor for coronary artery disease.

• Reduced compliance of the left ventricle (LV) secondary to LVH results in left ventricular diastolic dysfunction.

Key Points

• LVH reflects pressure and volume overload on the left ventricle.

• Concentric hypertrophy occurs in the presence of pressure overload with a stiff ventricle (Fig. 16-1).

• Eccentric LVH is more likely secondary to increased volume overload (eg., in hemodialysis patients).

• Diastolic function is worse in patients with LVH.

• Regression of LVH with normalization of left ventricular mass (LVM) can occur in patients after successful treatment with antihypertensive therapy.

Figure 16-1 Parasternal short axis view of concentric left ventricular hypertrophy.

Glomerulonephritis

• Glomerulonephritis may result in:

• LVH, right ventricular and septal hypertrophy.

• Dilated ventricles.

• Decreased ventricular contractility.

• Impairment in diastolic ventricular function.

Chronic Renal Failure

• Adolescents are at higher risk of cardiovascular events than younger children.

• Cardiac findings: cardiomyopathy (CM), arrhythmias, and cardiac arrest of unknown origin.

• African American race and female sex have been reported to be risk factors for cardiovascular disease in children and adolescents on dialysis.

Key Points

• LVH can develop even with mild to moderate chronic kidney disease.

• Impaired diastolic dysfunction may be seen in children with chronic kidney disease, on long-term dialysis, and after transplantation.

• Abnormalities in calcium-phosphate metabolism, particularly in dialysis patients, are associated with diastolic dysfunction.

• Increased incidence of valvular disease in those undergoing chronic dialysis:

• Age older than 14 years, female African American.

• Aortic valve (AV) and mitral valve (MV) disease are most often involved.

• Annular calcification.

Post-Kidney Transplantation

• Decreased systolic function, diastolic dysfunction, and increased LVM can persist even after transplantation.

Key Points

• The most common findings post-transplantation are:

• LVH.

• Left atrial enlargement.

• Left ventricular dilation.

• Systolic dysfunction.

Iron Overload Cardiomyopathy

• Myocardial injury due to excess iron deposition, which may occur in association with chronic renal failure/hemodialysis.

The Echo Exam: Step-by-Step Approach

Step 1: Evaluate Cardiac Size

• M-mode and two-dimensional (2D) assessment of cardiac dimensions.

• Assess for left ventricular dilation and/or LVH using measurements indexed to body surface area (BSA).

• Image using multiple planes including four-chamber (4C) and short axis views.

• Use indexed LVM to define LVH in pediatric patients (g/m^2.7).

• Height should be measured (in meters).

• LVM equation is 0.8{1.04[(LVED + left ventricular posterior wall thickness + interventricular septal thickness)³ − LVED³]} + 0.6, where LVED is left ventricular end-diastolic dimension.

• LVM is then indexed to height to the exponential power of 2.7.

• For patients older than 9 years old: more than 40 g/m^2.7 in girls and more than 45 g/m^2.7 in boys is abnormal.

Key Points

• Height and weight measurements should be obtained at the time of the echocardiogram to ensure accuracy rather than relying on patient history.

• M-mode is performed from a parasternal long axis view just below the MV leaflets.

• Leading edge to leading edge technique in end-diastole is used to measure

• LVED.

• Left posterior wall thickness.

• Interventricular septal thickness.

• To evaluate LVM in patients younger than 9 years of age, percentile curves should be referenced.

Step 2: Evaluate Systolic Cardiac Function

• Obtain end-diastolic and end-systolic measurements and calculate left ventricular fractional shortening (FS) using M-mode.

• Parasternal short axis or long axis view at the level of the papillary muscles.

• FS greater than 38% = hyperdynamic.

• FS less than 28% = reduced systolic function.

• Use the modified Simpson’s (disk summation) method for calculating ejection fraction (EF) to estimate left ventricular end-diastolic and end-systolic volumes.

• Use the apical 4C and two-chamber (2C) views (Fig. 16-2).

Figures 16-2 The modified Simpson method (disk summation) can be used to calculate left ventricular volumes. It involves tracing the left ventricular endocardial border in apical 4-chamber and 2-chamber views using the disk summation method for calculating ejection fraction based on estimating left ventricular volume in systole and diastole, as illustrated in A and B. Application of the modified Simpson method using an apical 4-chamber view is demonstrated estimating left ventricular end-systolic (C) and end-diastolic (D) volumes. As seen in the echo images, this technique requires adequate delineation of the left ventricular endocardium.

Step 3: Evaluate Diastolic Cardiac Function

• Ventricular relaxation occurs during isovolumic relaxation.

• Recorded from an apical 4C view at the MV leaflet tips.

• Use pulsed wave (PW) Doppler with the signal aligned parallel to mitral flow.

• Normal mitral inflow Doppler pattern.

• Isovolumic relaxation: brief interval between AV closure and the onset of ventricular filling (isovolumic relaxation time [IVRT]).

• Blood rapidly fills the left atrium (LA) with opening of the MV (E wave).

• E velocity of early maximum filling velocity.

• Filling then slows (deceleration time): E peak to intersection of the slope with the zero baseline.

• Left atrial contraction causes another peak velocity (atrial velocity or A wave).

• Tissue Doppler imaging (TDI).

• TDI is obtained at the lateral margin of the MV annulus from an apical 4C view.

• Time interval from the end to the onset of the mitral annular velocity pattern during diastole.

• Measurements include (Fig. 16-3).

• Early diastolic annular velocity (E′).

• Diastolic velocity with atrial contraction (A′).

• Isovolumic contraction time (IVCT).

• IVRT.

• Ejection time (ET).

• Used as an adjunct for evaluation of diastolic function.

• Less dependent on preload.

• Normal variation is less than 20%.

• In children with normal diastolic function, the E wave is larger than the A wave, reflecting that ventricular filling occurs primarily in early diastole.

• A reduced E/A ratio may be seen with diastolic dysfunction in chronic renal disease.

• Increased HR results in shorter duration of diastole with an increased A wave and lower E/A ratio.

• Impaired relaxation is associated with a prolonged IVRT.

• Decreased compliance and increased filling pressures are associated with a shortened IVRT.

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