Early diagnosis still remains a challenge in CTEPH, with a median time of 14 months between symptom onset and diagnosis in expert centres. A suspicion of PH is often raised by echocardiography, but an invasive right heart catheterisation is required to confirm it. Once PH is diagnosed, the presence of thromboembolic disease requires imaging. The recommended diagnostic algorithm stresses the importance of initial investigation using an echocardiogram and V/Q scan and confirmation with right heart catheter and pulmonary angiography (PA).

Both V/Q scanning and modern multidetector CT angiography (CTPA) may be accurate methods for the detection of CTEPH, with excellent diagnostic efficacy in expert hands (sensitivity, specificity, and accuracy of 100%, 93.7%, and 96.5% for V/Q and 96.1%, 95.2%, and 95.6% for CTPA). However, CTPA alone cannot exclude the disease, but may help identify pulmonary artery distension resulting in left main coronary artery compression, pulmonary parenchymal lesions (e.g. as complications from previous pulmonary infarctions), and bleeding from bronchial collateral arteries. Today, the gold standard imaging remains invasive pulmonary angiography (PAG) using native angiograms or a digital subtraction technique.

Historically the prognosis for patients with untreated CTEPH was poor, with a 5-year survival of 40 mmHg at presentation. More contemporary data from the European CTEPH registry have demonstrated a 70% 3-year survival in patients with CTEPH who do not undergo the surgical procedure of pulmonary endarterectomy (PEA). Recent data from an international CTEPH registry demonstrate that mortality in CTEPH is associated with New York Heart Association (NYHA) functional class IV, increased right atrial pressure, and a history of cancer. Furthermore, comorbidities such as coronary disease, left heart failure, and chronic obstructive pulmonary disease (COPD) are risk factors for mortality.

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.

In addition to evaluating the symptoms above, the health care provider may find decreased or no blood pressure in the arm or leg.

Tests to determine any underlying cause for thrombosis or embolism and to confirm presence of the obstruction may include:

- Doppler ultrasound, especially duplex ultrasonography. It may also involve transcranial doppler exam of arteries to the brain

- Echocardiography, sometimes involving more specialized techniques such as Transesophageal echocardiography (TEE) or myocardial contrast echocardiography (MCE) to diagnose myocardial infarction

- Arteriography of the affected extremity or organ Digital subtraction angiography is useful in individuals where administration of radiopaque contrast material must be kept to a minimum.

- Magnetic resonance imaging (MRI)

- Blood tests for measuring elevated enzymes in the blood, including cardiac-specific troponin T and/or troponin I, myoglobins, and creatine kinase isoenzymes. These indicate embolisation to the heart that has caused myocardial infarction. Myoglobins and creatine kinase are also elevated in the blood in embolisation in other locations.

- Blood cultures may be done to identify the organism responsible for any causative infection

- Electrocardiography (ECG) for detecting myocardial infarction

- Angioscopy using a flexible fiberoptic catheter inserted directly into an artery.

The diagnosis of portopulmonary hypertension is based on hemodynamic criteria:

1. . Portal hypertension and/or liver disease (clinical diagnosis—ascites/varices/splenomegaly)

2. . Mean pulmonary artery pressure—MPAP > 25 mmHg at rest

3. . Pulmonary vascular resistance—PVR > 240 dynes s cm−5

4. . Pulmonary artery occlusion pressure— PAOP 12 mmHg where TPG = MPAP − PAOP.

The diagnosis is usually first suggested by a transthoracic echocardiogram, part of the standard pre-transplantation work-up. Echocardiogram estimated pulmonary artery systolic pressures of 40 to 50 mm Hg are used as a screening cutoff for PPH diagnosis, with a sensitivity of 100% and a specificity as high as 96%. The negative predictive value of this method is 100% but the positive predictive value is 60%. Thereafter, these patients are referred for pulmonary artery catheterization.

The limitations of echocardiography are related to the derivative nature of non-invasive PAP estimation. The measurement of PAP by echocardiogram is made using a simplified Bernoulli equation. High cardiac index and pulmonary capillary wedge pressures, however, may lead to false positives by this standard. By one institution’s evaluation, the correlation between estimated systolic PAP and directly measured PAP was poor, 0.49. For these reasons, right heart catheterization is needed to confirm the diagnosis.

As a general rule, any diver who has breathed gas under pressure at any depth who surfaces unconscious, loses consciousness soon after surfacing, or displays neurological symptoms within about 10 minutes of surfacing should be assumed to be suffering from arterial gas embolism.

Symptoms of arterial gas embolism may be present but masked by environmental effects such as hypothermia, or pain from other obvious causes. Neurological examination is recommended when there is suspicion of lung overexpansion injury. Symptoms of decompression sickness may be very similar to, and confused with, symptoms of arterial gas embolism, however, treatment is basically the same. Discrimination between gas embolism and decompression sickness may be difficult for injured divers, and both may occur simultaneously. Dive history may eliminate decompression sickness in many cases, and the presence of symptoms of other lung overexpansion injury would raise the probability of gas embolism.

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)

Following diagnosis, mean survival of patients with PPH is 15 months. The survival of those with cirrhosis is sharply curtailed by PPH but can be significantly extended by both medical therapy and liver transplantation, provided the patient remains eligible.

Eligibility for transplantation is generally related to mean pulmonary artery pressure (PAP). Given the fear that those PPH patients with high PAP will suffer right heart failure following the stress of post-transplant reperfusion or in the immediate perioperative period, patients are typically risk-stratified based on mean PAP. Indeed, the operation-related mortality rate is greater than 50% when pre-operative mean PAP values lie between 35 and 50 mm Hg; if mean PAP exceeds 40-45, transplantation is associated with a perioperative mortality of 70-80% (in those cases without preoperative medical therapy). Patients, then, are considered to have a high risk of perioperative death once their mean PAP exceeds 35 mm_Hg.

Survival is best inferred from published institutional experiences. At one institution, without treatment, 1-year survival was 46% and 5-year survival was 14%. With medical therapy, 1-year survival was 88% and 5-year survival was 55%. Survival at 5 years with medical therapy followed by liver transplantation was 67%. At another institution, of the 67 patients with PPH from 1652 total cirrhotics evaluated for transplant, half (34) were placed on the waiting list. Of these, 16 (48%) were transplanted at a time when 25% of all patients who underwent full evaluation received new livers, meaning the diagnosis of PPH made a patient twice as likely to be transplanted, once on the waiting list. Of those listed for transplant with PPH, 11 (33%) were eventually removed because of PPH, and 5 (15%) died on the waitlist. Of the 16 transplanted patients with PPH, 11 (69%) survived for more than a year after transplant, at a time when overall one-year survival in that center was 86.4%. The three year post-transplant survival for patients with PPH was 62.5% when it was 81.02% overall at this institution.

There is no one single test for confirming that breathlessness is caused by pulmonary edema; indeed, in many cases, the cause of shortness of breath is probably multifactorial.

Low oxygen saturation and disturbed arterial blood gas readings support the proposed diagnosis by suggesting a pulmonary shunt. Chest X-ray will show fluid in the alveolar walls, Kerley B lines, increased vascular shadowing in a classical batwing peri-hilum pattern, upper lobe diversion (increased blood flow to the superior parts of the lung), and possibly pleural effusions. In contrast, patchy alveolar infiltrates are more typically associated with noncardiogenic edema

Lung ultrasound, employed by a healthcare provider at the point of care, is also a useful tool to diagnose pulmonary edema; not only is it accurate, but it may quantify the degree of lung water, track changes over time, and differentiate between cardiogenic and non-cardiogenic edema.

Especially in the case of cardiogenic pulmonary edema, urgent echocardiography may strengthen the diagnosis by demonstrating impaired left ventricular function, high central venous pressures and high pulmonary artery pressures.

Blood tests are performed for electrolytes (sodium, potassium) and markers of renal function (creatinine, urea). Liver enzymes, inflammatory markers (usually C-reactive protein) and a complete blood count as well as coagulation studies (PT, aPTT) are also typically requested. B-type natriuretic peptide (BNP) is available in many hospitals, sometimes even as a point-of-care test. Low levels of BNP (<100 pg/ml) suggest a cardiac cause is unlikely.

Prevention of atherosclerosis, which is a major risk factor of arterial embolism, can be performed e.g. by dieting, physical exercise and smoking cessation.

In case of high risk for developing thromboembolism, antithrombotic medication such as warfarin or coumadin may be taken prophylactically. Antiplatelet drugs may also be needed.

If a patent foramen ovale (PFO) is suspected, an examination by echocardiography may be performed to diagnose the defect. In this test, very fine bubbles are introduced into a patient's vein by agitating saline in a syringe to produce the bubbles, then injecting them into an arm vein. A few seconds later, these bubbles may be clearly seen in the ultrasound image, as they travel through the patient's right atrium and ventricle. At this time, bubbles may be observed directly crossing a septal defect, or else a patent foramen ovale may be opened temporarily by asking the patient to perform the Valsalva maneuver while the bubbles are crossing through the right heart – an action which will open the foramen flap and show bubbles passing into the left heart. Such bubbles are too small to cause harm in the test, but such a diagnosis may alert the patient to possible problems which may occur from larger bubbles, formed during activities like underwater diving, where bubbles may grow during decompression. A PFO test may be recommended for divers intending to expose themselves to relatively high decompression stress in deep technical diving.

Screening ECGs (either at rest or with exercise) are not recommended in those without symptoms who are at low risk. This includes those who are young without risk factors. In those at higher risk the evidence for screening with ECGs is inconclusive.

Additionally echocardiography, myocardial perfusion imaging, and cardiac stress testing is not recommended in those at low risk who do not have symptoms.

Some biomarkers may add to conventional cardiovascular risk factors in predicting the risk of future cardiovascular disease; however, the clinical value of some biomarkers is questionable.

The NIH recommends lipid testing in children beginning at the age of 2 if there is a family history of heart disease or lipid problems. It is hoped that early testing will improve lifestyle factors in those at risk such as diet and exercise.

Screening and selection for primary prevention interventions has traditionally been done through absolute risk using a variety of scores (ex. Framingham or Reynolds risk scores). This stratification has separated people who receive the lifestyle interventions (generally lower and intermediate risk) from the medication (higher risk). The number and variety of risk scores available for use has multiplied, but their efficacy according to a 2016 review was unclear due to lack of external validation or impact analysis. Risk stratification models often lack sensitivity for population groups and do not account for the large number of negative events among the intermediate and low risk groups. As a result, future preventative screening appears to shift toward applying prevention according to randomized trial results of each intervention rather than large-scale risk assessment.

Management has generally been reported to be conservative, though deaths have been reported.

- Removal from water

- Observation

- Diuretics and / or Oxygen when necessary

- Episodes are generally self-limiting in the absence of other medical problems

In those with underlying heart disease, effective control of congestive symptoms prevents pulmonary edema.

Dexamethasone is in widespread use for the prevention of high altitude pulmonary edema. Sildenafil is used as a preventive treatment for altitude-induced pulmonary edema and pulmonary hypertension, the mechanism of action is via phosphodiesterase inhibition which raises cGMP, resulting in pulmonary arterial vasodilation and inhibition of smooth muscle cell proliferation. While this effect has only recently been discovered, sildenafil is already becoming an accepted treatment for this condition, in particular in situations where the standard treatment of rapid descent has been delayed for some reason.

SIPE is estimated to occur in 1-2% of competitive open-water swimmers, with 1.4% of triathletes, 1.8% of combat swimmers and 1.1% of divers and swimmers reported in the literature.

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.

The diagnosis is made by transthoracic or transesophageal echocardiography, angiography, and more recently by CT angiography or MR Angiography.

Lung infarction, also known as pulmonary infarction, occurs when an artery to the lung becomes blocked and part of the lung dies. It is most often caused by pulmonary embolism.

Surgical correction should be considered in the presence of significant left to right shunting (Qp:Qs ≥ 2:1) and pulmonary hypertension. This involves creation of an inter-atrial baffle to redirect the pulmonary venous return into the left atrium. Alternatively, the anomalous vein can be re-implanted directly into the left atrium.

In treating pulmonary insufficiency, it should be determined if pulmonary hypertension is causing the problem to therefore begin the most appropriate therapy as soon as possible (primary pulmonary hypertension or secondary pulmonary hypertension due to thromboembolism). Furthermore, pulmonary insufficiency is generally treated by addressing the underlying condition, in certain cases, the pulmonary valve may be surgically replaced.

Blood pressure medication reduces cardiovascular disease in people at risk, irrespective of age, the baseline level of cardiovascular risk, or baseline blood pressure. The commonly-used drug regimens have similar efficacy in reducing the risk of all major cardiovascular events, although there may be differences between drugs in their ability to prevent specific outcomes. Larger reductions in blood pressure produce larger reductions in risk, and most people with high blood pressure require more than one drug to achieve adequate reduction in blood pressure.

Statins are effective in preventing further cardiovascular disease in people with a history of cardiovascular disease. As the event rate is higher in men than in women, the decrease in events is more easily seen in men than women. In those at risk, but without a history of cardiovascular disease (primary prevention), statins decrease the risk of death and combined fatal and non-fatal cardiovascular disease. A United States guideline recommends statins in those who have a 12% or greater risk of cardiovascular disease over the next ten years. Niacin, fibrates and CETP Inhibitors, while they may increase HDL cholesterol do not affect the risk of cardiovascular disease in those who are already on statins.

Anti-diabetic medication may reduce cardiovascular risk in people with Type 2 Diabetes, although evidence is not conclusive. A meta-analysis in 2009 including 27,049 participants and 2,370 major vascular events showed a 15% relative risk reduction in cardiovascular disease with more-intensive glucose lowering over an average follow-up period of 4.4 years, but an increased risk of major hypoglycemia.

Aspirin has been found to be of only modest benefit in those at low risk of heart disease as the risk of serious bleeding is almost equal to the benefit with respect to cardiovascular problems. In those at very low risk it is not recommended. The United States Preventive Services Task Force recommends against use of aspirin for prevention in women less than 55 and men less than 45 years old; however, in those who are older it is recommends in some individuals.

The use of vasoactive agents for people with pulmonary hypertension with left heart disease or hypoxemic lung diseases may cause harm and unnecessary expense.

The use of heparin following surgery is common if there are no issues with bleeding. Generally, a risk-benefit analysis is required, as all anticoagulants lead to an increased risk of bleeding. In people admitted to hospital, thrombosis is a major cause for complications and occasionally death. In the UK, for instance, the Parliamentary Health Select Committee heard in 2005 that the annual rate of death due to thrombosis was 25,000, with at least 50% of these being hospital-acquired. Hence "thromboprophylaxis" (prevention of thrombosis) is increasingly emphasized. In patients admitted for surgery, graded compression stockings are widely used, and in severe illness, prolonged immobility and in all orthopedic surgery, professional guidelines recommend low molecular weight heparin (LMWH) administration, mechanical calf compression or (if all else is contraindicated and the patient has recently suffered deep vein thrombosis) the insertion of a vena cava filter. In patients with medical rather than surgical illness, LMWH too is known to prevent thrombosis, and in the United Kingdom the Chief Medical Officer has issued guidance to the effect that preventative measures should be used in medical patients, in anticipation of formal guidelines.

There is ongoing research on the treatment of ARDS by interferon (IFN) beta-1a to aid in preventing leakage of vascular beds. Traumakine (FP-1201-lyo), is a recombinant human IFN beta-1a drug developed by Faron pharmaceuticals, is undergoing international phase-III clinical trials after an open-label, early-phase trial showed a 81% reduction-in-odds of 28-day mortality in ICU patients with ARDS. The drug is known to function by enhancing lung CD73 expression and increasing production of anti-inflammatory adenosine, such that vascular leaking and escalation of inflammation are reduced.

Radiologic imaging has long been a criterion for diagnosis of ARDS. While original definitions of ARDS specified that correlative chest X-ray findings were required for diagnosis, the diagnostic criteria have been expanded over time to accept CT and ultrasound findings as equally contributory. Generally, radiographic findings of fluid accumulation (pulmonary edema) affecting both lungs and unrelated to increased cardiopulmonary vascular pressure (such as in heart failure) may be suggestive of ARDS.

Ultrasound findings suggestive of ARDS include the following:

- Anterior subpleural consolidations

- Absence or reduction of lung sliding

- “Spared areas” of normal parenchyma

- Pleural line abnormalities (irregular thickened fragmented pleural line)

- Nonhomogeneous distribution of B-lines (a characteristic ultrasound finding suggestive of fluid accumulation in the lungs)