The diagnosis of pulmonary heart disease is not easy as both lung and heart disease can produce similar symptoms. Therefore, the differential diagnosis should assess:

Among the investigations available to determine cor pulmonale are:

- Chest x-ray – right ventricular hypertrophy, right atrial dilatation, prominent pulmonary artery

- ECG – right ventricular hypertrophy, dysrhythmia, P pulmonale (characteristic peaked P wave)

- Thrombophilia screen- to detect chronic venous thromboembolism (proteins C and S, antithrombin III, homocysteine levels)

If heart disease and lung disease have been excluded, a ventilation/perfusion scan is performed to rule out CTEPH. If unmatched perfusion defects are found, further evaluation by CT pulmonary angiography, right heart catheterization, and selective pulmonary angiography is performed.

For people considered likely to have PAH based on the above tests, the specific associated condition is then determined based on the physical examination, medical/family history and further specific diagnostic tests (for example, serological tests to detect underlying connective tissue disease, HIV infection or hepatitis, ultrasonography to confirm the presence of portal hypertension, echocardiography/cardiac magnetic resonance imaging for congenital heart disease, laboratory tests for schistosomiasis, and high resolution CT for PVOD and pulmonary capillary hemangiomatosis). Routine lung biopsy is discouraged in patients with PAH, because of the risk to the patient and because the findings are unlikely to alter the diagnosis and treatment.

Tests that are frequently done that are not sensitive for PE, but can be diagnostic.

- Chest X-rays are often done on people with shortness of breath to help rule-out other causes, such as congestive heart failure and rib fracture. Chest X-rays in PE are rarely normal, but usually lack signs that suggest the diagnosis of PE (for example, Westermark sign, Hampton's hump).

- Ultrasonography of the legs, also known as leg doppler, in search of deep venous thrombosis (DVT). The presence of DVT, as shown on ultrasonography of the legs, is in itself enough to warrant anticoagulation, without requiring the V/Q or spiral CT scans (because of the strong association between DVT and PE). This may be a valid approach in pregnancy, in which the other modalities would increase the risk of birth defects in the unborn child. However, a negative scan does not rule out PE, and low-radiation dose scanning may be required if the mother is deemed at high risk of having a pulmonary embolism.

In massive and submassive PE, dysfunction of the right side of the heart may be seen on echocardiography, an indication that the pulmonary artery is severely obstructed and the right ventricle, a low-pressure pump, is unable to match the pressure. Some studies (see below) suggest that this finding may be an indication for thrombolysis. Not every person with a (suspected) pulmonary embolism requires an echocardiogram, but elevations in cardiac troponins or brain natriuretic peptide may indicate heart strain and warrant an echocardiogram, and be important in prognosis.

The specific appearance of the right ventricle on echocardiography is referred to as the "McConnell's sign". This is the finding of akinesia of the mid-free wall but a normal motion of the apex. This phenomenon has a 77% sensitivity and a 94% specificity for the diagnosis of acute pulmonary embolism in the setting of right ventricular dysfunction.

The epidemiology of pulmonary heart disease (cor pulmonale) accounts for 7% of all heart disease in the U.S. According to Weitzenblum, et al., the mortality that is related to cor pulmonale is not easy to ascertain, as it is a complication of COPD.

Bilharzial cor pulmonale is the condition of right sided heart failure secondary to fibrosis and sclerosis of the pulmonary artery branches. It results from shifting of the "Schistosoma haematobium" ova from the pelvic and vescial plexus to the pulmonary artery branches where they settle and produce granuloma and fibrosis.

Bilharzial cor pulmonale occurs in "Schistosoma mansoni", when the portal pressure rises more than the systemic pressure. So blood will pass from the portal circulation to the systemic circulation carrying "Schistosoma mansoni" ova to reach the lungs.

This condition leads to Pulmonary hypertension, right ventricular hypertrophy and failure.

No system of diagnostic criteria has been agreed on as the gold standard for heart failure. The National Institute for Health and Care Excellence recommends measuring brain natriuretic peptide (BNP) followed by ultrasound of the heart if positive. This is recommended in those with shortness of breath. In those with heart failure who worsen both a BNP and a troponin are recommended to help determine likely outcomes.

Chest X-rays are frequently used to aid in the diagnosis of CHF. In a person who is compensated, this may show cardiomegaly (visible enlargement of the heart), quantified as the cardiothoracic ratio (proportion of the heart size to the chest). In left ventricular failure, there may be evidence of vascular redistribution ("upper lobe blood diversion" or "cephalization"), Kerley lines, cuffing of the areas around the bronchi, and interstitial edema. Ultrasound of the lung may also be able to detect Kerley lines.

COPD may need to be differentiated from other causes of shortness of breath such as congestive heart failure, pulmonary embolism, pneumonia, or pneumothorax. Many people with COPD mistakenly think they have asthma. The distinction between asthma and COPD is made on the basis of the symptoms, smoking history, and whether airflow limitation is reversible with bronchodilators at spirometry. Tuberculosis may also present with a chronic cough and should be considered in locations where it is common. Less common conditions that may present similarly include bronchopulmonary dysplasia and obliterative bronchiolitis. Chronic bronchitis may occur with normal airflow and in this situation it is not classified as COPD.

A chest X-ray and complete blood count may be useful to exclude other conditions at the time of diagnosis. Characteristic signs on X-ray are overexpanded lungs, a flattened diaphragm, increased retrosternal airspace, and bullae, while it can help exclude other lung diseases, such as pneumonia, pulmonary edema, or a pneumothorax. A high-resolution computed tomography scan of the chest may show the distribution of emphysema throughout the lungs and can also be useful to exclude other lung diseases. Unless surgery is planned, however, this rarely affects management. An analysis of arterial blood is used to determine the need for oxygen; this is recommended in those with an FEV less than 35% predicted, those with a peripheral oxygen saturation less than 92%, and those with symptoms of congestive heart failure. In areas of the world where alpha-1 antitrypsin deficiency is common, people with COPD (particularly those below the age of 45 and with emphysema affecting the lower parts of the lungs) should be considered for testing.

In the diagnosis of tricuspid insufficiency a chest x-ray will demonstrate right heart enlargement. An echocardiogram will assess the chambers of the heart, as well as, right ventricular pressure. Cardiac magnetic resonance may also be used as a diagnostic tool, and finally, cardiac catheterization may determine the extent of the regurgitation.

Respiratory diseases may be investigated by performing one or more of the following tests

- Biopsy of the lung or pleura

- Blood test

- Bronchoscopy

- Chest x-ray

- Computed tomography scan, including high-resolution computed tomography

- Culture of microorganisms from secretions such as sputum

- Ultrasound scanning can be useful to detect fluid such as pleural effusion

- Pulmonary function test

- Ventilation—perfusion scan

In terms of treatment for tricuspid insufficiency prosthetic valve substitutes can be used, though artificial prostheses may cause thrombo‐embolic phenomena(bioprostheses may have a degeneration problem). Some evidence suggests that there are no significant differences between a mechanical or biological tricuspid valve in a recipient.

Generally, surgical treatment of tricuspid regurgitation is not indicated when it has arisen as a result of right ventricular dilatation. In such instances of secondary tricuspid regurgitation, the mainstay of therapy is medical. When left-sided heart failure is the cause, the individual is instructed to decrease intake of salt. Medications in this case may include diuretics and angiotensin-converting enzyme inhibitors.

Respiratory disease is a common and significant cause of illness and death around the world. In the US, approximately 1 billion "common colds" occur each year. A study found that in 2010, there were approximately 6.8 million emergency department visits for respiratory disorders in the U.S. for patients under the age of 18. In 2012, respiratory conditions were the most frequent reasons for hospital stays among children.

In the UK, approximately 1 in 7 individuals are affected by some form of chronic lung disease, most commonly chronic obstructive pulmonary disease, which includes asthma, chronic bronchitis and emphysema.

Respiratory diseases (including lung cancer) are responsible for over 10% of hospitalizations and over 16% of deaths in Canada.

In 2011, respiratory disease with ventilator support accounted for 93.3% of ICU utilization in the United States.

Cor bovinum refers to a massive hypertrophy of the left ventricle of the heart due to volume overload, usually in earlier times in the context of tertiary syphilis but currently more often due to chronic aortic regurgitation, hypertensive and ischaemic heart disease.

Due to Syphilitic aortitis (a complication of tertiary syphilis) the aortic valve ring becomes dilated. The free margins of valve cusps no longer approximate leading to aortic valve insufficiency. As blood regurgitates into the left ventricle between each systole, volume overload ensues and the ventricular wall hypertrophies in an attempt to maintain cardiac output and blood pressure. The massive ventricle can lead to a heart weighing over 1000 grams (the weight of a normal heart is about 350 grams), referred to as "Cor Bovinum" [Latin for cow's heart.]

Fluri and Gebbers define cor bovinum as a heart exceeding 500 g in weight. Looking through autopsies on Internal Medicine patients at the Kantonsspital Luzern, they found 415 cases out of 1181 autopsies in the two periods 1978-81 and 1997-2000. Cor bovinum was found in 25.3% of cases in the earlier period, with mean age at death 67.7 years, and in the later period 20.6% with mean age 74.3 years. The male female ratio was 4:1. "In 93% of all patients with CB, we found coronary atherosclerosis as a sign of high blood pressure and in 79% a COPD."

In 84% of cases the cause of death was directly related to the cor bovinum, but in 37% the cause of death was still unclear. They concluded that cor bovinum was a decreasing but still frequent autopsy finding. High blood pressure, COPD and male sex were the main risk factors. The decreasing incidence was ascribed to improved medical management: they mention treatments for high blood pressure and coronary artery disease, which suggests that "COPD" in their abstract refers to the latter.

In arterial blood-gas sampling, a small amount of blood is taken from an artery, usually in the wrist. The blood is then checked for oxygen and carbon-dioxide levels. This test shows how well the lungs are taking in oxygen.

Magnetic resonance imaging (MRI), also called nuclear magnetic resonance (NMR) scanning, uses powerful magnets to show pleural effusions and tumors.

In the differential diagnosis (finding the correct diagnosis between diseases that have overlapping features) of some obstructive lung diseases, DPB is often considered. A number of DPB symptoms resemble those found with other obstructive lung diseases such as asthma, chronic bronchitis, and emphysema. Wheezing, coughing with sputum production, and shortness of breath are common symptoms in such diseases, and obstructive respiratory functional impairment is found on pulmonary function testing. Cystic fibrosis, like DPB, causes severe lung inflammation, excess mucus production, and infection; but DPB does not cause disturbances of the pancreas nor the electrolytes, as does CF, so the two diseases are different and probably unrelated. DPB is distinguished by the presence of lesions that appear on X-rays as nodules in the bronchioles of both lungs; inflammation in all tissue layers of the respiratory bronchioles; and its higher prevalence among individuals with East Asian lineage.

DPB and bronchiolitis obliterans are two forms of primary bronchiolitis. Specific overlapping features of both diseases include strong cough with large amounts of often pus-filled sputum; nodules viewable on lung X-rays in the lower bronchi and bronchiolar area; and chronic sinusitis. In DPB, the nodules are more restricted to the respiratory bronchioles, while in OB they are often found in the membranous bronchioles (the initial non-cartilaginous section of the bronchiole, that divides from the tertiary bronchus) up to the secondary bronchus. OB is a bronchiolar disease with worldwide prevalence, while DPB has more localized prevalence, predominantly in Japan. Prior to clinical recognition of DPB in recent years, it was often misdiagnosed as bronchiectasia, COPD, IPF, phthisis miliaris, sarcoidosis or alveolar cell carcinoma.

The diagnosis of an individual suspected of having "fat embolism syndrome" can be done via the following tests and methods:

The diagnosis of DPB requires analysis of the lungs and bronchiolar tissues, which can require a lung biopsy, or the more preferred high resolution computed tomography (HRCT) scan of the lungs. The diagnostic criteria include severe inflammation in all layers of the respiratory bronchioles and lung tissue lesions that appear as nodules within the terminal and respiratory bronchioles in both lungs. The nodules in DPB appear as opaque lumps when viewed on X-rays of the lung, and can cause airway obstruction, which is evaluated by a pulmonary function test, or PFT. Lung X-rays can also reveal dilation of the bronchiolar passages, another sign of DBP. HRCT scans often show blockages of some bronchiolar passages with mucus, which is referred to as the "tree-in-bud" pattern. Hypoxemia, another sign of breathing difficulty, is revealed by measuring the oxygen and carbon dioxide content of the blood, using a blood test called arterial blood gas. Other findings observed with DPB include the proliferation of lymphocytes (white blood cells that fight infection), neutrophils, and foamy histiocytes (tissue macrophages) in the lung lining. Bacteria such as "H. influenzae" and "P. aeruginosa" are also detectable, with the latter becoming more prominent as the disease progresses. The white blood, bacterial and other cellular content of the blood can be measured by taking a complete blood count (CBC). Elevated levels of IgG and IgA (classes of immunoglobulins) may be seen, as well as the presence of rheumatoid factor (an indicator of autoimmunity). Hemagglutination, a clumping of red blood cells in response to the presence of antibodies in the blood, may also occur. Neutrophils, beta-defensins, leukotrienes, and chemokines can also be detected in bronchoalveolar lavage fluid injected then removed from the bronchiolar airways of individuals with DPB, for evaluation.

According to the American Thoracic Society (ATS), the general diagnostic criteria for asbestosis are:

- Evidence of structural pathology consistent with asbestosis, as documented by imaging or histology

- Evidence of causation by asbestos as documented by the occupational and environmental history, markers of exposure (usually pleural plaques), recovery of asbestos bodies, or other means

- Exclusion of alternative plausible causes for the findings

The abnormal chest x-ray and its interpretation remain the most important factors in establishing the presence of pulmonary fibrosis. The findings usually appear as small, irregular parenchymal opacities, primarily in the lung bases. Using the ILO Classification system, "s", "t", and/or "u" opacities predominate. CT or high-resolution CT (HRCT) are more sensitive than plain radiography at detecting pulmonary fibrosis (as well as any underlying pleural changes). More than 50% of people affected with asbestosis develop plaques in the parietal pleura, the space between the chest wall and lungs. Once apparent, the radiographic findings in asbestosis may slowly progress or remain static, even in the absence of further asbestos exposure. Rapid progression suggests an alternative diagnosis.

Asbestosis resembles many other diffuse interstitial lung diseases, including other pneumoconiosis. The differential diagnosis includes idiopathic pulmonary fibrosis (IPF), hypersensitivity pneumonitis, sarcoidosis, and others. The presence of pleural plaquing may provide supportive evidence of causation by asbestos. Although lung biopsy is usually not necessary, the presence of asbestos bodies in association with pulmonary fibrosis establishes the diagnosis. Conversely, interstitial pulmonary fibrosis in the absence of asbestos bodies is most likely not asbestosis. Asbestos bodies in the absence of fibrosis indicate exposure, not disease.