Blood returning to the lungs is pumped through the lungs by the right ventricle of the heart. Blood pressure in the lungs is ordinarily rather low, for example 20/10, in contrast to body blood pressure which is usually around 110/70.
Resistance to blood flow through the lungs puts a strain on the right ventricle. At early stages, the right ventricle is able to compensate but as the resistance increases and the pressures go higher, the right ventricle cannot keep up. At early stages, shortness of breath occurs with moderate physical activity but as it worsens, it takes less and less physical activity to cause shortness of breath.
Physicians can often make a preliminary diagnosis of heart failure with only a medical history and careful physical examination.Physicians use information from the echocardiogram for calculating the ejection fraction (the percent of the blood pumped out during each heartbeat), which is important for determining the severity of heart failure. Researchers are looking for biologic factors (called markers) that will confirm a diagnosis or suggest a better or worse prognosis.
Blood pressure in the lung can be estimated and the size and function of the right ventricle assessed by echocardiography with Doppler. This non-invasive test uses sound waves to image the chambers of the heart. However, Doppler echocardiograms are notoriously inaccurate when the pulmonary hypertension is mild or when there is simultaneous presence of lung scarring. A small protein released by stretched heart muscle (BNP-brain natriuretic peptide) can be measured by a simple blood test. Elevated levels are a strong clue for suspecting pulmonary hypertension.
Brain natriuretic peptide was originally isolated from the mammalian brain and acts as a cardiac hormone resembling atrial natriuretic peptide. Brain natriuretic peptide is synthesized primarily by the ventricles, and its expression in the ventricles is induced in ventricular overload and hypertrophy. These observations suggest the possible involvement of this peptide in the pathophysiology of hypertrophic cardiomyopathy.
Brain natriuretic peptide, also called B-type natriuretic peptide (BNP), is a protein that your heart and blood vessels produce. BNP acts as a natural diuretic, eliminating fluid, relaxing blood vessels and funneling sodium into the urine.When your heart is damaged, your body secretes very high levels of BNP into your bloodstream in an effort to ease the strain on your heart. BNP levels may also rise if you have new or increasing chest pain (unstable angina) or after a heart attack. BNP levels can also be an indicator of heart failure treatment progress over time.
Called N-terminal pro-brain natriuretic peptide, or NT-proBNP, the biomarker is among a group of blood elements being studied for their ability to provide prognostic information after heart attacks. Other such markers include troponin T and C-reactive protein (CRP).
NT-proBNP is a hormone that is released from the heart’s lower ventricles in response to increased wall tension. Its levels increase after heart attack. Previous studies have found that the NT-proBNP can predict death among patients with a common type of acute coronary syndrome (ACS).The plasma concentrations of both BNP are increased in patients with asymptomatic and symptomatic left ventricular dysfunction.
While recent research found that BNP increases considerably with age and is higher in women than men, this study found that baseline levels of NT-proBNP are also independently related to low body weight, kidney function and clinical factors indicating cardiovascular damage such as high blood pressure, previous heart attack or stroke, angina pectoris and diabetes mellitus. They found that it signaled risk independently of other risk factors, such as age and prior heart attack.
Natriuretic peptides can be used as prognostic and diagnostic markers of Chagas’ disease. It has been reported that brain natriuretic peptide predicts survival in Chagas’ disease more effectively than does atrial natriuretic peptide. Magnetic resonance imaging is an excellent marker for monitoring heart functionality from the acute through the chronic phase of infection and for monitoring the efficacy of cardioprotective or immune therapeutic agents.
A trial that used blood levels of a biomarker called brain natriuretic peptide (BNP) to guide treatment of heart failure more than halved the incidence of death or hospitalization for the condition over 15 months, French cardiologists report.
Just 24 percent of the 110 trial participants whose drug treatment was adjusted according to BNP levels reached those critical end points of death or hospitalization. That compared to 52 percent of those who did not get BNP monitoring.
There were seven deaths from heart failure in the BNP-monitored group, compared to 11 in the non-monitored patients. The overall incidence of hospitalization was about the same in both groups, but just 22 hospital stays due to heart failure complications in the monitored group compared to 48 among patients whose BNP levels were not monitored.
The major difference in medical treatment was use of higher doses of beta-blocker and ACE inhibitor drugs in the BNP-monitored group, the researchers said.
BNP is a protein produced by the muscle cells of the heart ventricles as a response to excess stretching of those cells. Tests of BNP blood levels are used to help diagnosis heart failure, a condition in which the heart progressively loses its ability to pump blood, and to assess the prognosis for people with heart failure. Most drugs used to treat heart failure lower BNP levels.
The study participants, whose average age was 65, had essentially similar symptoms at the start of the trial, although those in the BNP-monitored group had a slightly lower average ejection fraction, which measures the heart's blood-pumping ability.
"This is an important study, because it provides additional information about the role that BNP measurement can play in helping physicians adjust treatment for heart failure," said Dr. Gregg C. Fonarow, co-director of the University of California, Los Angeles, Preventive Cardiology Program. "Many medications can be used to treat heart failure, and guiding those medications can be an art. This trial shows that, beyond standard care, BNP monitoring allows better adjustment of medications," Fonarow said.
Dr. Marvin A. Konstam, chief of cardiology at Tufts-New England Medical Center in Boston, agreed. "This is helpful information. It begins to build a case that monitoring BNP can facilitate medication adjustment for better outcome."
But it was a relatively small study, both Konstam and Fonarow said, and the final word is yet to come. "Additional trials involving more centers will be needed to confirm these findings," Fonarow said. "This is helpful additional information, but we need those additional trials before we can routinely recommend BNP monitoring."
At least two such trials are now under way, Konstam said, with results expected before long.
Konstam had one word of caution about the French results. The trial was not "blinded," meaning the doctors knew which patients were being monitored for BNP levels, and that knowledge might have affected their mode of treatment, he said. "It is a significant possibility and one that has to be clarified," he said.
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