it is an established fact that influenza a has a predilection for individuals with cardiac diseases , especially with mitral stenosis . it usually involves the upper and lower respiratory tracts and is accompanied by fever , headache , myalgias and generalized weakness . the recent pandemic which occurred in march 2009 was caused by an influenza a / h1n1 virus . the typical manifestation of the disease is that of an acute illness which progresses rapidly and the patient usually recovers in a period of three to five days , but some patients develop pulmonary complications like primary influenza viral pneumonia , secondary bacterial pneumonia , mixed viral and bacterial pneumonia and worsening of chronic obstructive lung diseases . extrapulmonary complications like reye 's syndrome , myositis , rhabdomyolysis and myoglobinuria , myocarditis , pericarditis , encephalitis , transverse myelitis and guillain - barre syndrome ( gbs ) , toxic shock syndrome associated with staphylococcus aureus or group a streptococcus are also known to occur . a 19-year - old male patient presented to the emergency with complaints of high - grade fever since 8 - 12 days , not associated with chills , along with difficulty in breathing and hemoptysis since one day . on admission his temperature was 102f , blood pressure ( bp ) = 94/58 mm of hg , heart rate ( hr ) = 152 bpm , spo2 = 88% with oxygen support . on examination the patient was conscious , tachypneic , dyspneic and was using accessory muscles for breathing . . cardiac examination revealed a loud first heart sound , tachycardia ; no murmur was , however , audible . neck veins were engorged and abdominal examination revealed hepatomegaly 4 cm below the costal margins . routine blood tests , arterial blood gas analysis and a throat swab were sent for examination . chest x - ray revealed b / l homogenous opacities involving middle and basal lung fields [ figure 1 ] . abg showed ph = 7.40 , pco2 = 22 mm of hg , po2 = 56 mm of hg , hco3 = 23 meq / l . the patient was given bi - pap support and empiric treatment was started keeping a possibility of viral pneumonitis among the differentials . complete blood count ( cbc ) showed a total leucocyte count of 8820/mm , dlc = p85% , l13% , e2% , hb = 11.8g / dl , platelet count = 94000/mm , blood urea = 38 mg / dl , sr . creatinine = 0.9 mg / dl , sr.k = 3.4 meq / l , sr . bilirubin = 4.2 mg / dl , ( direct = 2.1 mg / dl , indirect = 2.1 mg / dl ) globulin = 2.6 mg / dl , ast = 116u / l , alt = 48u / l , sr . alkaline phosphatase = 91 u / l and cpk - mb = 28 ng / dl . a 2d - echo showed severe mitral valve stenosis ( valve area = 0.93 cm ) , moderate tricuspid regurgitation , moderate pulmonary hypertension and a dilated right and left atrium . the throat swab culture was positive for influenza a. the patient gradually improved over a period of ten days and was subsequently referred to cardiothoracic surgery for management of mitral stenosis . a high proportion of allegedly pure viral pneumonias have been reported in patients with heart disease , especially mitral stenosis . although these patients have not usually been in frank heart failure , it is possible that circulatory factors have played some part in their deaths . primary influenza viral pneumonia has a predilection for individuals with cardiac diseases , particularly those with mitral stenosis . it has been observed that the presence of mitral stenosis in a patient predisposes him / her to infection with influenza a. so patients with a known lesion must be considered as high - risk candidates for influenza during pandemics . autopsy sample of young females during the h1n1 epidemic in 2009 - 10 showed grade 2 mitral stenosis . extrapulmonary complications of influenza such as cardiac involvement like myocarditis , pericarditis have also been reported in some earlier studies . in influenza outbreaks since 1918 , primary viral pneumonia has occurred predominantly among individuals with cardiovascular diseases , especially rheumatic heart disease with mitral stenosis . hence patients suffering from influenza a must be closely observed and if they show symptoms of cardiac failure , they must be evaluated for the presence of underlying mitral stenosis . this is in agreement with the present case wherein the patient presented with acute respiratory distress and was diagnosed as a case of influenza a , and had an underlying but undiagnosed mitral stenosis .
infection with influenza virus is uncommon in the present times , though a number of cases were reported during pandemics in 1918 in various regions of america . 
 we report a case where a young male patient presented to the hospital with a clinical picture of acute respiratory distress syndrome that turned out to be a viral pneumonia caused by influenza a virus and it aggravated an underlying yet undiagnosed mitral valve stenosis .