Right heart failure overview
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The right ventricle was previously recognized as a simple conduit between the systemic and the pulmonary circulation until recently when its importance in maintaining hemodynamic stability and organ function has been recognized. In fact, right heart function acts as an important prognostic factor in congenital heart diseases, pulmonary hypertension and right heart failure. Right heart failure can be defined as failure of the right ventricle to pump blood into the lungs adequately. It consists of an intricate clinical syndrome resulting from several functional and structural cardiovascular disorders that alter right ventricular right ventricle filling and/or ejection capacity. Furthermore, it has been shown that isolated right ventricular failure, despite its rarity as compared to left ventricular failure, which carries a worse prognosis. Hence, right heart failure presents distinctive challenges in identification and management. Right heart failure is also used interchangeably with cor pulmonale when the pathology is caused by an underlying lung disease.
There are many different ways to categorize right heart failure, which includes whether the abnormality is due to insufficient contraction (systolic dysfunction); or due to insufficient relaxation of the heart (diastolic dysfunction), or to both; whether the problem is primarily increased venous back pressure (preload), or failure to supply adequate arterial perfusion (afterload); whether the abnormality is due to low cardiac output with high systemic vascular resistance or high cardiac output with low vascular resistance (low-output heart failure vs. high-output heart failure); degree of functional impairment conferred by the abnormality (as reflected in the New York Heart Association Functional Classification); and the degree of coexisting illness: i.e. heart failure/systemic hypertension, heart failure/pulmonary hypertension, heart failure/diabetes, heart failure/chronic renal failure, etc.
The pathophysiological processes underlying right heart failure can be divided broadly into three: decreased right ventricular contractility, right ventricular pressure overload, right ventricular volume overload . The right ventricle tries to adapt acutely by dilatation and chronically by hypertrophy. Whether dilatation or hypertrophy occur, right heart failure gets further exacerbated as a result of these adaptive mechanisms.
There are acute and chronic causes of right heart failure. Acute right heart failure is associated with right ventricular dilation. Chronic right heart failure is often associated with right ventricular hypertrophy.
Epidemiology and Demographics
The prevalence of heart failure has been increasing due to the increase in the aging population, the early detection, preventive measures and improvement in the therapy. The prevalence of heart failure in the United States was estimated in 2006 to be 5.8 million people of all ages with an estimated incidence of 10/1000 for individuals older than 65 years of age.
Natural History, Complications and Prognosis
Right heart failure, if left undiagnosed and untreated, may lead to impaired quality of life and eventually death. There are several factors that define this natural history depending mainly on the underlying etiology or mechanism of injury, the onset of illness, how early was treatment initiated and other comorbidities.
In the initial approach to a patient with RHF, it is important to determine the underlying etiology, assess the functional status of the patient, determine the presence of any end organ damage (liver and kidney most notably), and any other associated conditions.
History and Symptoms
Right heart failure is frequently associated with shortness of breath, exercise intolerance and coughing, and in later stages chest discomfort and swelling of the feet or ankles. According to the recent 2009 updated guidelines on diagnosis and management of right heart failure published by the Canadian Cardiovascular Society Consensus Conference guidelines on heart failure, right heart failure should be suspected as the diagnosis whenever a patient is presenting with unexplained complaints of exercise intolerance or hypotension with signs of elevated jugular venous pressure (JVP), peripheral edema (feet or ankles), hepatomegaly or a combination of any of these clinical signs.
Physical exam should consist of a thorough cardiovascular exam, an abdominal exam, and examination of the extremities. Findings to be aware of are cyanosis, JVD, S2 and S3 heart sounds, ascites, hepatomegaly, and pedal edema.
Laboratory tests are useless in the diagnosis of heart failure, however they are essential in identifying possible precipitating factors of decompensation, assessing severity of the heart failure, monitoring the side effects of medical treatment and some serve as prognostic markers. In addition, in patients with right heart failure, an arterial blood gas can be useful in assessing the degree of hypoxemia. This can in turn be used to guide therapy with oxygen.
Right heart failure is often accompanied by right ventricular hypertrophy and right ventricular dilation. The general electrocardiographic findings of right ventricular hypertrophy include right axis deviation, an R/S ratio > 1 in V1, and the presence of P pulmonale.
The plain chest radiograph has limited utility in identifying right heart failure. It might show evidence of the underlying cause of right heart failure like pulmonary embolism or congenital heart diseases.
Currently, the basis of therapy for right heart failure is most importantly cautious diuresis, sinus rhythm maintenance and management of the underlying cause whenever feasible. Management of right heart failure, which is largely empiric, can be tailored for etiology specific therapy such as anticoagulation in the case of a pulmonary embolism or antibiotics in the case of endocarditis. Management also comprises of optimizing right ventricular preload, afterload and contractility. Since atrial fibrillation and high grade AV block cause detrimental hemodynamic instability in the setting of a right heart failure in particular, maintaining sinus rhythm and AV synchrony is important .
Surgical intervention in right heart failure is mainly indicated in valvular pathologies and congenital heart diseases that are causing worsening of heart failure despite adequate medical interventions. In addition, early surgical interventions in these pathologies have been associated with improved survival and functional status (exercise tolerance for example which serves as an important prognostic indicator in right heart failure) of the patients. . Treating primary pulmonary hypertension often leads to greater stamina and a longer life. In some cases, a lung transplant or heart-lung transplant can extend survival.
Future or Investigational Therapies
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