The noradrenaline plasma concentration and its gradient across the lung

Hemofiltration in Heart Failure

In patients with severe congestive heart failure (CHF), removal of edema by hemofiltration is associated with significant clinical and hemodynamic improvement, correction of hyponatremia, restoration of urine output and diuretic responsiveness, and with a striking fall in neurohormonal activation. Through these effects, hemofiltration is able to interrupt the progression of CHF toward refractoriness, and to revert the clinical condition of CHF patients to a lower functional class.

Fluid refilling from the overhydrated interstitium is the major compensatory mechanism in the prevention of hypovolemia during hemofiltration.

Hemofiltration can also be beneficial in patients who have only moderate cardiac insufficiency (NYHA classes II and III) and in whom over-hydration is restricted to the pulmonary district significantly contributing to limiting patients functional capacity. In this setting, hemofiltration, differently from diuretics, is able to remove the increased lung water content and to improve clinical condition, exercise capacity and lung function.

Pathophysiology of cardiorenal syndrome in decompensated heart failure: role of lung-right heart-kidney interaction

Cardiorenal syndrome (CRS) is defined as an interaction of cardiac disease with renal dysfunction that leads to diuretic resistance and renal function worsening, mainly with heart failure (HF) exacerbation. Hemodynamic variables linking heart and kidney are renal blood flow (cardiac output) and perfusion pressure, i.e., the aortic - renal venous pressure gradient. CRS has traditionally been interpreted as related to defective renal perfusion and arterial underfilling and, more recently, to elevation in central venous pressure transmitted back to renal veins. Our suggestion is that in a setting where aortic pressure is generally low, due to heart dysfunction and to vasodrepressive therapy, the elevated central venous pressure (CVP) contributes to lower the renal perfusion pressure below the threshold of kidney autoregulation (≤80mm Hg) and causes renal perfusion to become directly pressure dependent. This condition is associated with high neurohumoral activation and preglomerular vasoconstriction that may preserve pressure, but may decrease filtration fraction and glomerular filtration rate and enhance proximal tubular sodium absorption. Thus, congestion worsens and drives the vicious cycle of further sodium retention and HF exacerbation. Lowering CVP by targeting the lung-right heart interaction that sustains elevated CVP seems to be a more rational approach rather than reducing intravascular volume. This interaction is crucial and consists of a cascade with stepwise development of pulmonary post-capillary hypertension, precapillary arteriolar hypertone, right ventricular overload and enlargement with tricuspid incompetence and interference with left ventricular filling (interdependence). The resultant CVP rise is transmitted to the renal veins, eventually drives CRS and leads to a positive feedback loop evolving towards HF refractoriness.

Cardiac and renal dysfunction in chronic heart failure: relation to neurohumoral activation and prognosis

BACKGROUND

In chronic heart failure (CHF), cardiac dysfunction is considered the major determinant of neurohumoral activation but the role of renal impairment has not been defined. We investigated the relationship between both cardiac and renal dysfunction and neurohumoral activation, and their possible influence on prognosis.

METHODS

Hemodynamics, renal function, plasma neurohormones, and long-term follow-up were evaluated in 148 CHF patients, grouped according to systolic volume index (SVI) and serum creatinine (CRE) values: SVI > 28 mL/m2 and CRE < 1.5 mg/dL (group I, n = 55), SVI < 28 mL/m2 and CRE < 1.5 mg/dL (group II, n = 37), SVI > 28 mL/m2 and CRE > 1.5 mg/dL (group III, n = 25), SVI < 28 mL/m2 and CRE > 1.5 mg/dL (group IV, n = 31).

RESULTS

Neurohormones progressively increased from Group I through IV and correlated with both cardiac and renal function. The hemodynamic pattern was similar in patients with normal or abnormal renal function, whereas neurohormones were only moderately increased in the former group and markedly increased in the latter group. Long-term survival progressively decreased from Group I through IV and was significantly poorer in patients with renal dysfunction.

CONCLUSIONS

Our study confirms that, in CHF, neurohumoral activation is strictly related to long-term survival and that many factors contribute to its development and progression; among these, cardiac and renal dysfunction seem to play a major role.