Influence of the pericardium on left ventricular diastolic pressure-volume curves in dogs with sustained volume overload

Successful Use of Continuous Ambulatory Peritoneal Dialysis in Refractory Heart Failure

Four patients with end-stage heart failure, massive ascites refractory to medical interventions and a variable degree of renal failure were treated successfuly with CAPD for eight to 24 months. The New York Heart Association functional class improved in all four. In two patients, who presented initially with signs and symptoms mainly of right-sided heart failure, ejection fraction improved. Each day dialysis achieved a significant degree of ultrafiltration and a negative sodium balance. We propose that CAPD is an alternative therapeutic modality in patients with severe heart failure refractory to the conventional medical treatment.

The advent of potent diuretics and preload and afterload reducing agents has had a major impact in the treatment of refractory congestive heart failure. Recently, captopril, an angiotensinconverting enzyme inhibitor, has been used with major benefit in some patients (I). However, some patients still do not respond to these treatments and their management presents a major therapeutic challenge. Furthermore, overzealous therapy with diuretics may lead to intravascular volume depletion resulting in hypotension, azotemia and electrolyte disturbances which further complicate their management.

In the past, intermittent peritoneal dialysis (IPD) or hemodialysis (HD) has been used to remove fluid from patients with intractable edema due to heart failure (2 7). But the benefit is only transient and fluid accumulates again, requiring repeated sessions of acute dialysis. However, hypotension is a frequent complication during either form of acute dialysis especially in hemodynamically unstable patients due to rapid removal of large amounts of fluid from intravascular space.

Continuous ambulatory peritoneal dialysis (CAPD), whose main characteristic is the slow continuous removal of sodium and water, offers obvious advantages in patients with intractable heart failure.

This paper describes our experience of four patients with intractable heart failure who have been treated with CAPD for eight to 24 months.

Operative contractility: A functional concept of the inotropic state

1. Initial unsuccessful attempts to evaluate ventricular function in terms of the 'heart as a pump' led to focusing on the 'heart as a muscle' and to the concept of myocardial contractility. However, no clinically ideal index exists to assess the contractile state. The aim of the present study was to develop a mathematical model to assess cardiac contractility. 2. A tri-axial system was conceived for preload (PL), afterload (AL) and contractility, where stroke volume (SV) was represented as the volume of the tetrahedron. Based on this model, 'operative' contractility ('OperCon') was calculated from the readily measured values of PL, AL and SV. The model was tested retrospectively under a variety of different experimental and clinical conditions, in 71 studies in humans and 29 studies in dogs. A prospective echocardiographic study was performed in 143 consecutive subjects to evaluate the ability of the model to assess contractility when SV and PL were measured volumetrically (mL) or dimensionally (cm). 3. With inotropic interventions, OperCon changes were comparable to those of ejection fraction (EF), velocity of shortening (Vcf) and dP/dt-max. Only with positive inotropic interventions did elastance (Ees) show significantly larger changes. With load manipulations, OperCon showed significantly smaller changes than EF and Ees and comparable changes to Vcf and dP/dt-max. Values of OperCon were similar when AL was represented by systolic blood pressure or wall stress and when volumetric or dimensional values were used. 4. Operative contractility is a reliable, simple and versatile method to assess cardiac contractility.