Symptoms of pulmonary embolism are typically sudden in onset and may include one or many of the following: dyspnea (shortness of breath), tachypnea (rapid breathing), chest pain of a "pleuritic" nature (worsened by breathing), cough and hemoptysis (coughing up blood). More severe cases can include signs such as cyanosis (blue discoloration, usually of the lips and fingers), collapse, and circulatory instability because of decreased blood flow through the lungs and into the left side of the heart. About 15% of all cases of sudden death are attributable to PE.

On physical examination, the lungs are usually normal. Occasionally, a pleural friction rub may be audible over the affected area of the lung (mostly in PE with infarct). A pleural effusion is sometimes present that is exudative, detectable by decreased percussion note, audible breath sounds, and vocal resonance. Strain on the right ventricle may be detected as a left parasternal heave, a loud pulmonary component of the second heart sound, and/or raised jugular venous pressure. A low-grade fever may be present, particularly if there is associated pulmonary hemorrhage or infarction.

As smaller pulmonary emboli tend to lodge in more peripheral areas without collateral circulation they are more likely to cause lung infarction and small effusions (both of which are painful), but not hypoxia, dyspnea or hemodynamic instability such as tachycardia. Larger PEs, which tend to lodge centrally, typically cause dyspnea, hypoxia, low blood pressure, fast heart rate and fainting, but are often painless because there is no lung infarction due to collateral circulation. The classic presentation for PE with pleuritic pain, dyspnea and tachycardia is likely caused by a large fragmented embolism causing both large and small PEs. Thus, small PEs are often missed because they cause pleuritic pain alone without any other findings and large PEs often missed because they are painless and mimic other conditions often causing ECG changes and small rises in troponin and BNP levels.

PEs are sometimes described as massive, submassive and nonmassive depending on the clinical signs and symptoms. Although the exact definitions of these are unclear, an accepted definition of massive PE is one in which there is hemodynamic instability such as sustained low blood pressure, slowed heart rate, or pulselessness.

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.

Pulmonary embolism (PE) is a blockage of an artery in the lungs by a substance that has traveled from elsewhere in the body through the bloodstream (embolism). Symptoms of a PE may include shortness of breath, chest pain particularly upon breathing in, and coughing up blood. Symptoms of a blood clot in the leg may also be present such as a red, warm, swollen, and painful leg. Signs of a PE include low blood oxygen levels, rapid breathing, rapid heart rate, and sometimes a mild fever. Severe cases can lead to passing out, abnormally low blood pressure, and sudden death.

PE usually results from a blood clot in the leg that travels to the lung. The risk of blood clots is increased by cancer, prolonged bed rest, smoking, stroke, certain genetic conditions, estrogen-based medication, pregnancy, obesity, and after some types of surgery. A small proportion of cases are due to the embolization of air, fat, or amniotic fluid. Diagnosis is based on signs and symptoms in combination with test results. If the risk is low a blood test known as a D-dimer will rule out the condition. Otherwise a CT pulmonary angiography, lung ventilation/perfusion scan, or ultrasound of the legs may confirm the diagnosis. Together deep vein thrombosis and PE are known as venous thromboembolism (VTE).

Efforts to prevent PE include beginning to move as soon as possible after surgery, lower leg exercises during periods of sitting, and the use of blood thinners after some types of surgery. Treatment is typically with blood thinners such as heparin or warfarin. Often these are recommended for six months or longer. Severe cases may require thrombolysis using medication such as tissue plasminogen activator (tPA), or may require surgery such as a pulmonary thrombectomy. If blood thinners are not appropriate, a vena cava filter may be used.

Pulmonary emboli affect about 430,000 people each year in Europe. In the United States between 300,000 and 600,000 cases occur each year, which results in between 50,000 and 200,000 deaths. Rates are similar in males and females. They become more common as people get older.

Symptoms may begin quickly or slowly depending on the size of the embolus and how much it blocks the blood flow. Symptoms of embolisation in an organ vary with the organ involved but commonly include:

- Pain in the involved body part

- Temporarily decreased organ function

Later symptoms are closely related to infarction of the affected tissue. This may cause permanently decreased organ function.

For example, symptoms of myocardial infarction mainly include chest pain, dyspnea, diaphoresis (an excessive form of sweating), weakness, light-headedness, nausea, vomiting, and palpitations.

Symptoms of limb infarction include coldness, decreased or no pulse beyond the site of blockage, pain, muscle spasm, numbness and tingling, pallor and muscle weakness, possibly to the grade of paralysis in the affected limb.

Arterial emboli often occur in the legs and feet. Some may occur in the brain, causing a stroke, or in the heart, causing a heart attack. Less common sites include the kidneys, intestines, and eyes.

The most common symptom of pulmonary edema is difficulty breathing, but may include other symptoms such as coughing up blood (classically seen as pink, frothy sputum), excessive sweating, anxiety, and pale skin. Shortness of breath can manifest as orthopnea (inability to lie down flat due to breathlessness) and/or paroxysmal nocturnal dyspnea (episodes of severe sudden breathlessness at night). These are common presenting symptoms of chronic pulmonary edema due to left ventricular failure. The development of pulmonary edema may be associated with symptoms and signs of "fluid overload"; this is a non-specific term to describe the manifestations of left ventricular failure on the rest of the body and includes peripheral edema (swelling of the legs, in general, of the "pitting" variety, wherein the skin is slow to return to normal when pressed upon), raised jugular venous pressure and hepatomegaly, where the liver is enlarged and may be tender or even pulsatile. Other signs include end-inspiratory crackles (sounds heard at the end of a deep breath) on auscultation and the presence of a third heart sound.

Pulmonary edema is fluid accumulation in the tissue and air spaces of the lungs. It leads to impaired gas exchange and may cause respiratory failure. It is due to either failure of the left ventricle of the heart to remove blood adequately from the pulmonary circulation (cardiogenic pulmonary edema), or an injury to the lung parenchyma or vasculature of the lung (noncardiogenic pulmonary edema). Treatment is focused on three aspects: firstly improving respiratory function, secondly, treating the underlying cause, and thirdly avoiding further damage to the lung. Pulmonary edema, especially acute, can lead to fatal respiratory distress or cardiac arrest due to hypoxia. It is a cardinal feature of congestive heart failure. The term is from the Greek (oídēma, "swelling"), from οἰδέω (oidéō, "I swell").

Arterial embolism can cause occlusion in any part of the body. It is a major cause of infarction, tissue death due to the blockage of blood supply.

An embolus lodging in the brain from either the heart or a carotid artery will most likely be the cause of a stroke due to ischemia.

An arterial embolus might originate in the heart (from a thrombus in the left atrium, following atrial fibrillation or be a septic embolus resulting from endocarditis). Emboli of cardiac origin are frequently encountered in clinical practice. Thrombus formation within the atrium occurs mainly in patients with mitral valve disease, and especially in those with mitral valve stenosis (narrowing), with atrial fibrillation (AF). In the absence of AF, pure mitral regurgitation has a low incidence of thromboembolism.

The risk of emboli forming in AF depends on other risk factors such as age, hypertension, diabetes, recent heart failure, or previous stroke.

Thrombus formation can also take place within the ventricles, and it occurs in approximately 30% of anterior-wall myocardial infarctions, compared with only 5% of inferior ones. Some other risk factors are poor ejection fraction (<35%), size of infarct, and the presence of AF. In the first three months after infarction, left-ventricle aneurysms have a 10% risk of emboli forming.

Patients with prosthetic valves also carry a significant increase in risk of thromboembolism. Risk varies, based on the valve type (bioprosthetic or mechanical); the position (mitral or aortic); and the presence of other factors such as AF, left-ventricular dysfunction, and previous emboli.

Emboli often have more serious consequences when they occur in the so-called "end circulation": areas of the body that have no redundant blood supply, such as the brain and heart.

Embolism can be classified as to where it enters the circulation either in arteries or in veins. Arterial embolism are those that follow and, if not dissolved on the way, lodge in a more distal part of the systemic circulation. Sometimes, multiple classifications apply; for instance a pulmonary embolism is classified as an arterial embolism as well, in the sense that the clot follows the pulmonary artery carrying deoxygenated blood away from the heart. However, pulmonary embolism is generally classified as a form of venous embolism, because the embolus forms in veins, e.g. deep vein thrombosis.

Dressler syndrome was, historically, a phenomenon complicating about 7% of myocardial infarctions; however, in the era of percutaneous coronary intervention, it is very uncommon. The disease consists of a persistent low-grade fever, chest pain (usually pleuritic in nature), pericarditis (usually evidenced by a pericardial friction rub), and/or a pericardial effusion. The symptoms tend to occur 2–3 weeks after myocardial infarction, but can also be delayed for a few months. It tends to subside in a few days, and very rarely leads to pericardial tamponade. An elevated ESR is an objective, yet nonspecific, laboratory finding.

Chest pain is the most common symptom of acute myocardial infarction and is often described as a sensation of tightness, pressure, or squeezing. Pain radiates most often to the left arm, but may also radiate to the lower jaw, neck, right arm, back, and upper abdomen. The pain most suggestive of an acute MI, with the highest likelihood ratio, is pain radiating to the right arm and shoulder. Similarly, chest pain similar to a previous heart attack is also suggestive. The pain associated with MI is usually diffuse, does not change with position, and lasts for more than 20 minutes. Levine's sign, in which a person localizes the chest pain by clenching one or both fists over their sternum, has classically been thought to be predictive of cardiac chest pain, although a prospective observational study showed it had a poor positive predictive value. Pain that responds to nitroglycerin does not indicate the presence or absence of a myocardial infarction.

The effects of a circulatory collapse vary based on the type of collapse it is. Peripheral collapses usually involve abnormally low blood pressure and result in collapsed arteries and/or veins, leading to oxygen deprivation to tissues, organs, and limbs.

Acute collapse can result from heart failure causing the primary vessels of the heart to collapse, perhaps combined with cardiac arrest.

Myocardial infarction (MI) refers to tissue death (infarction) of the heart muscle (myocardium). It is a type of acute coronary syndrome, which describes a sudden or short-term change in symptoms related to blood flow to the heart. Unlike other causes of acute coronary syndromes, such as unstable angina, a myocardial infarction occurs when there is cell death, as measured by a blood test for biomarkers (the cardiac protein troponin or the cardiac enzyme CK-MB). When there is evidence of an MI, it may be classified as an ST elevation myocardial infarction (STEMI) or Non-ST elevation myocardial infarction (NSTEMI) based on the results of an ECG.

The phrase "heart attack" is often used non-specifically to refer to a myocardial infarction and to sudden cardiac death. An MI is different from—but can cause—cardiac arrest, where the heart is not contracting at all or so poorly that all vital organs cease to function, thus causing death. It is also distinct from heart failure, in which the pumping action of the heart is impaired. However, an MI may lead to heart failure.

A very large range of medical conditions can cause circulatory collapse. These include, but are not limited to:

- Surgery, particularly on patients who have lost blood.

- Blood clots, including the use of some platelet-activating factor drugs in some animals and humans

- Dengue Fever

- Severe dehydration

- Shock (including, among other types, many cases of cardiogenic shock- e.g., after a myocardial infarction or during heart failure; distributive shock, hypovolemic shock, resulting from large blood loss; and severe cases of septic shock)

- Heart Disease (myocardial infarction- heart attack; acute or chronic congestive or other heart failure, ruptured or dissecting aneurysms; large, especially hemorrhagic, stroke; some untreated congenital heart defects; failed heart transplant)

- Superior mesenteric artery syndrome

- Drugs that affect blood pressure

- Drinking seawater

- As a complication of dialysis

- Intoxicative inhalants

The left side of the heart is responsible for receiving oxygen-rich blood from the lungs and pumping it forward to the systemic circulation (the rest of the body except for the pulmonary circulation). Failure of the left side of the heart causes blood to back up (be congested) into the lungs, causing respiratory symptoms as well as fatigue due to insufficient supply of oxygenated blood. Common respiratory signs are increased rate of breathing and increased "work" of breathing (non-specific signs of respiratory distress). Rales or crackles, heard initially in the lung bases, and when severe, throughout the lung fields suggest the development of pulmonary edema (fluid in the alveoli). Cyanosis which suggests severe low blood oxygen, is a late sign of extremely severe pulmonary edema.

Additional signs indicating left ventricular failure include a laterally displaced apex beat (which occurs if the heart is enlarged) and a gallop rhythm (additional heart sounds) may be heard as a marker of increased blood flow or increased intra-cardiac pressure. Heart murmurs may indicate the presence of valvular heart disease, either as a cause (e.g. aortic stenosis) or as a result (e.g. mitral regurgitation) of the heart failure.

"Backward" failure of the left ventricle causes congestion of the lungs' blood vessels, and so the symptoms are predominantly respiratory in nature. Backward failure can be subdivided into the failure of the left atrium, the left ventricle or both within the left circuit. The patient will have dyspnea (shortness of breath) on exertion and in severe cases, dyspnea at rest. Increasing breathlessness on lying flat, called orthopnea, occurs. It is often measured in the number of pillows required to lie comfortably, and in orthopnea, the patient may resort to sleeping while sitting up. Another symptom of heart failure is paroxysmal nocturnal dyspnea: a sudden nighttime attack of severe breathlessness, usually several hours after going to sleep. Easy fatigability and exercise intolerance are also common complaints related to respiratory compromise.

"Cardiac asthma" or wheezing may occur.

Compromise of left ventricular "forward" function may result in symptoms of poor systemic circulation such as dizziness, confusion and cool extremities at rest.

Signs and symptoms of ischemic cardiomyopathy include sudden fatigue, shortness of breath, dizziness and palpitations.

Right-sided heart failure is often caused by pulmonary heart disease (cor pulmonale), which is usually caused by difficulties of the pulmonary circulation, such as pulmonary hypertension or pulmonic stenosis.

Physical examination may reveal pitting peripheral edema, ascites, and liver enlargement. Jugular venous pressure is frequently assessed as a marker of fluid status, which can be accentuated by eliciting hepatojugular reflux. If the right ventricular pressure is increased, a parasternal heave may be present, signifying the compensatory increase in contraction strength.

"Backward" failure of the right ventricle leads to congestion of systemic capillaries. This generates excess fluid accumulation in the body. This causes swelling under the skin (termed peripheral edema or anasarca) and usually affects the dependent parts of the body first (causing foot and ankle swelling in people who are standing up, and sacral edema in people who are predominantly lying down). Nocturia (frequent nighttime urination) may occur when fluid from the legs is returned to the bloodstream while lying down at night. In progressively severe cases, ascites (fluid accumulation in the abdominal cavity causing swelling) and liver enlargement may develop. Significant liver congestion may result in impaired liver function (congestive hepatopathy), and jaundice and even coagulopathy (problems of decreased or increased blood clotting) may occur.

Alveolar lung diseases, are a group of diseases that mainly affect the alveoli of the lungs.

Alveolar disease is visible on chest radiography as small, ill-defined nodules of homogeneous density centered on the acini or bronchioles. The nodules coalesce early in the course of disease, such that the nodules may only be seen as soft fluffy edges in the periphery.

When the nodules are centered on the hilar regions, the chest x-ray may develop what is called the "butterfly," or "batwing" appearance. The nodules may also have a segmental or lobar distribution. Air alveolograms and air bronchograms can also be seen.

These findings appear soon after the onset of symptoms and change rapidly thereafter.

A segmental or lobar pattern may be apparent after aspiration pneumonia, atelectasis, lung contusion, localized pulmonary edema, obstructive pneumonia, pneumonia, pulmonary embolism with infarction, or tuberculosis.

Coronary thrombosis is the formation of a blood clot inside a blood vessel of the heart. This blood clot restricts blood flow within the heart. It is associated with narrowing of blood vessels subsequent to clotting. The condition is considered as a type of ischaemic heart disease, also known as a heart attack or myocardial infarction.

Thrombosis in the heart can lead to a myocardial infarction. Coronary thrombosis and myocardial infarction are sometimes used as synonyms, although this is technically inaccurate as the thrombosis refers to the blocking of blood vessels, while the infarction refers to the tissue death due to the consequent loss of blood flow to the heart tissue. The heart contains many connecting blood vessels, and depending upon the location of the thrombosis, the infarction may cause no symptoms. Coronary thrombosis is caused by atherosclerosis.This is when there is build up of cholesterol and fats in the artery walls. So the blood will clot because there isn't enough room for it to flow. The main causes of coronary thrombosis are stress, smoking, high blood pressure, and lack of exercise. Symptoms are sharp pains around the chest area, breathing difficulties, dizziness, and fainting. This is treated by taking Aspirin, Nitrates, or Beta Blockers.

Coronary thrombosis can be a complication associated with drug-eluting stents.

Pulmonary embolism classically presents with an acute onset of shortness of breath. Other presenting symptoms include pleuritic chest pain, cough, hemoptysis, and fever. Risk factors include deep vein thrombosis, recent surgery, cancer, and previous thromboembolism. It must always be considered in those with acute onset of shortness of breath owing to its high risk of mortality. Diagnosis however may be difficult and Wells Score is often used to assess the clinical probability. Treatment, depending on severity of symptoms typically start with anticoagulants, presence of ominous signs (low blood pressure), may warrant the use of thrombolytic drugs.

Acute coronary syndrome frequently presents with retrosternal chest discomfort and difficulty catching the breath. It however may atypically present with shortness of breath alone. Risk factors include old age, smoking, hypertension, hyperlipidemia, and diabetes. An electrocardiogram and cardiac enzymes are important both for diagnosis and directing treatment. Treatment involves measures to decrease the oxygen requirement of the heart and efforts to increase blood flow.

A myocardial infarction may compromise the function of the heart as a pump for the circulation, a state called heart failure. There are different types of heart failure; left- or right-sided (or bilateral) heart failure may occur depending on the affected part of the heart, and it is a low-output type of failure. If one of the heart valves is affected, this may cause dysfunction, such as mitral regurgitation in the case of left-sided coronary occlusion that disrupts the blood supply of the papillary muscles. The incidence of heart failure is particularly high in patients with diabetes and requires special management strategies.

Dressler syndrome needs to be differentiated from pulmonary embolism, another identifiable cause of pleuritic (and non-pleuritic) chest pain in people who have been hospitalized and/or undergone surgical procedures within the preceding weeks.

Left ventricular thrombus is a blood clot (thrombus) in the left ventricle of the heart. LVT is a common complication of acute myocardial infarction (AMI). Typically the clot is a mural thrombus, meaning it is on the wall of the ventricle. The primary risk of LVT is the occurrence of cardiac embolism, in which the thrombus detaches from the ventricular wall and travels through the circulation and blocks blood vessels. Blockage can be especially damaging in the heart or brain (stroke).