High-output Cardiac Failure: A Forgotten Phenotype in Clinical Practice

Abstract

Introduction: The knowledge on high-output cardiac failure (HOCF) has greatly improved in the last two decades. One of the advances was the identification of a new phenotype of HOCF, characterized by absence of ventricular dilation, already associated with liver disease, arteriovenous fistulas (AVF), lung disease, myelodysplastic syndromes, and obesity. However, it has been noted that any aetiology can present with one of the two phenotypes, depending on the evolution. Objective: To describe, through an integrative review, the physiopathology and aetiologies of HOCF and to discuss phenotypes associated with this condition. Methods: Revisions, guidelines, case-controls, cohort studies and clinical studies were searched in MEDLINE and LILACS, using the connectives in the "cardiac output, high" database [MeSH Terms] OR "high cardiac output" [All Fields]. Discussion: Two distinct phenotypes are currently described in the HOCF, regardless of the aetiology: 1) one with enlarged cardiac chambers; and 2) with normal heart chambers. The mechanisms related to HOCF are vasodilation, arteriovenous shunts that cause increased microvascular density, reduced systemic vascular resistance (RSVR), and high metabolism. These mechanisms lead to activation of the renin-angiotensin-aldosterone system, sodium and water retention, activation of neprilysin, of the sodium-glucose-2 transporter, which promote interstitial fibrosis, ventricular remodeling and a consequent increase in cardiac output >8L/min. Conclusion: Many aetiologies of HOCF have been described and some of them are potentially curable. Prompt recognition of this condition and proper treatment may lead to better outcomes.

Obesity-Related High-Output Heart Failure

“…Symptoms observed in high-output HF were reported to be similar to those in other types of HF and were not specific to obesity-related high-output HF 5,17,23,24 . These symptoms included fatigue, dyspnea (at rest, with exertion, or positional when supine), palpitations, and exercise intolerance 17,24,25 .…”

“…An increase in blood volume and CO has been observed in obese patients without HF owing to the increased metabolic demands of excess adipose tissue 24 . Two different phenotypes have been identified in obesity-related high-output HF: one with enlarged cardiac chambers and another with normal cardiac chambers 23 . If the myocardium must adapt to the increased demand, the left ventricle dilates and eccentric hypertrophy remodeling occurs 17,24 .…”

“…The pathophysiologic mechanisms for fluid retention and congestion in high-output HF are similar to low-output HF 4 . Neurohormonal systems such as the adrenergic (sympathetic) nervous system and renin-angiotensin-aldosterone system are known to be activated in individuals who only have obesity or HF including obesity-related high-output HF 5,23,25 . Low blood pressure activates baroreceptors that are part of the adrenergic nervous system and causes an increase in sympathetic stimulation 5,24 .…”

“…Most of the articles discussed obesity-related high-output HF along with the many other causes of high-output HF. 4,5,23,24 One article specifically focused on the pathophysiologic mechanisms of obesity-related high-output HF 17 and another article focused on differentiating phenotypes of high-output HF and hypervolemic HF from HF with preserved ejection fraction. 25 One article discussed 2 different phenotypes that are observed in all types of high-output HF.…”

“…4 Other articles did not provided specific parameters for obesity-related high-output HF but identified that high-output HF presents with an elevated CI (≥4 L/min/m 2 ), 25 elevated CO (>8 L/min), 17 or either CI or CO could be elevated for diagnosis. 5,23,24 Body mass index was used to describe obesity in all but 1 article, in which no description of obesity was provided. 24 The BMI values used to define obesity for obesity-related high-output HF were different and included the following: 35 kg/m 2 or greater, 17 30 kg/m 2 or greater, 5 and approximately 35 to 50 kg/m 2 .…”