Medical and Legal Terms Used on This Site

1. Medical terms Cardiology / Critical Care

Acute myocardial infarction (AMI)

A condition in which a coronary artery supplying blood to the heart muscle becomes suddenly blocked, leading to death of heart muscle tissue. Plain language: what is commonly called a “heart attack.”

Coronary arteries

Arteries that branch off from the aorta and supply oxygenated blood to the heart muscle. Major branches include the right coronary artery (RCA), left main trunk (LMT), left anterior descending artery (LAD), and left circumflex artery (LCx). Plain language: the blood vessels that feed the heart itself.

Heart failure

A clinical syndrome in which the heart cannot pump enough blood to meet the body’s needs, due to impaired contraction (systolic dysfunction), impaired relaxation (diastolic dysfunction), or both. Common causes include ischemic heart disease, valvular disease, and cardiomyopathy. Plain language: the heart has become too weak or too stiff to pump enough blood around the body.

PCI (Percutaneous Coronary Intervention)

A catheter-based procedure in which a thin tube is inserted into an artery (often from the wrist or groin) and advanced to the coronary arteries to open narrowed or blocked vessels using balloons and/or stents. Plain language: a “catheter procedure” to reopen blocked heart arteries.

CABG (Coronary Artery Bypass Grafting)

An open-heart surgical procedure in which graft vessels (such as the internal thoracic artery or saphenous vein) are used to bypass severely narrowed or blocked coronary arteries and restore blood flow to the heart muscle. Plain language: bypass surgery that creates a new route for blood to go around blocked heart arteries.

Coronary artery perforation

A serious complication of PCI in which the wall of a coronary artery is torn through, allowing blood to leak outside the vessel into surrounding structures such as the pericardial sac or mediastinum. Plain language: a hole is accidentally made in a heart artery, letting blood escape where it should not go.

Perforation (of a vessel or organ)

Formation of a hole that penetrates the wall of a blood vessel or hollow organ (such as the intestine, stomach, or esophagus). It may occur due to disease or as an iatrogenic complication of a medical procedure (e.g., catheterization, endoscopy). Plain language: an unintended hole is made in a blood vessel or organ so that contents leak out where they should not.

Coronary artery dissection

A tear in the inner layer of the coronary artery wall, creating a false channel where blood can accumulate and obstruct blood flow. Plain language: the inner wall of the heart artery peels, and blood flow can be blocked.

Arterial dissection

A condition in which a tear develops in the inner layer of an arterial wall, allowing blood to enter the vessel wall and create a “false lumen,” which may obstruct normal blood flow or rupture. Plain language: the inner lining of an artery splits, and blood gets inside the wall, which can block flow or cause dangerous bleeding.

Aortic injury / aortic dissection

Damage to the wall of the aorta (the main artery leaving the heart), which can include tearing of the inner layers (dissection) and potentially fatal bleeding. Plain language: a serious tear or injury to the body’s main artery.

Pericardium / pericardial sac

A double-layered membrane that encloses the heart. The space between the visceral and parietal pericardial layers (the pericardial cavity) normally contains a small amount of lubricating fluid. Plain language: the thin “bag” that surrounds the heart, with a small amount of fluid inside to let the heart move smoothly.

Pericardial fluid / pericardial effusion (when abnormal)

Fluid contained in the pericardial cavity. Under normal conditions only a small amount is present; accumulation of excess fluid or blood is called pericardial effusion and may lead to cardiac tamponade. Plain language: the fluid inside the sac around the heart. Too much of it can squeeze the heart.

Cardiac tamponade

A life-threatening condition in which fluid or blood accumulates within the pericardial sac, compressing the heart and preventing it from filling and pumping effectively. Plain language: pressure from fluid around the heart makes it unable to pump properly, leading to shock and death if not treated quickly.

Pericardiocentesis / pericardial drainage

A procedure in which a needle or catheter is inserted into the pericardial space to remove fluid or blood and relieve cardiac tamponade. Plain language: a drainage procedure to remove fluid or blood from around the heart.

Pleural effusion

Accumulation of fluid in the pleural space — the potential space between the lung and the chest wall. Causes include heart failure, infection, malignancy, trauma, and others. Plain language: fluid collecting around the lungs inside the chest.

Hemothorax

Accumulation of blood in the pleural cavity (the space between the lung and chest wall), often due to trauma or iatrogenic injury. Plain language: blood pooling inside the chest around the lungs.

Tension hemothorax

A form of hemothorax in which increasing pressure from accumulating blood compresses the lung and shifts mediastinal structures, severely impairing circulation. Plain language: blood in the chest builds up so much that it crushes the lung and heart area, causing a life-threatening state.

Acute subdural hematoma

A rapid accumulation of blood between the dura mater (outer membrane of the brain) and the surface of the brain, usually caused by head trauma. Plain language: a dangerous blood clot that forms between the skull and the brain after a head injury.

Shock liver / ischemic hepatitis

Severe liver dysfunction caused by prolonged low blood pressure and inadequate blood flow (shock), leading to marked elevation of liver enzymes. Plain language: the liver is damaged because it did not get enough blood during shock.

Acute kidney injury / “shock kidney”

Sudden loss of kidney function due to reduced blood flow during shock, resulting in decreased urine output and accumulation of metabolic waste products. Plain language: the kidneys fail because blood flow was too low for too long.

Disseminated intravascular coagulation (DIC)

A serious condition in which widespread activation of the clotting system leads to the formation of small clots throughout the body, consuming platelets and coagulation factors and eventually causing severe bleeding. Plain language: the blood starts clotting all over the body, uses up clotting factors, and then causes dangerous bleeding.

Sepsis / septic shock

A life-threatening organ dysfunction caused by an overwhelming infection; septic shock is the most severe form, with profound circulatory and metabolic abnormalities. Plain language: a severe infection that spreads through the body and can cause the organs to fail.

Intubation and mechanical ventilation

Placement of a tube into the trachea (windpipe) and use of a ventilator to support or replace spontaneous breathing. Plain language: using a breathing machine with a tube placed into the airway to help the patient breathe.

PEEP (Positive End-Expiratory Pressure)

A ventilator setting that maintains a positive pressure in the lungs at the end of expiration to prevent alveolar collapse and improve oxygenation. Excessive PEEP can reduce venous return and lower blood pressure, and must be used cautiously in conditions such as cardiac tamponade. Plain language: a setting on the breathing machine that keeps a small amount of pressure in the lungs when breathing out so they don’t collapse — but if too high, it can drop the blood pressure.

Extubation

Removal of the endotracheal tube once a patient no longer requires mechanical ventilation. Plain language: taking out the breathing tube when the patient is ready to breathe on their own.

Sedation

Administration of medications to reduce consciousness, anxiety, or agitation, commonly used during mechanical ventilation. Plain language: using medicines to keep a patient calm or unconscious while on a ventilator.

IABP (Intra-Aortic Balloon Pumping)

A mechanical circulatory support device in which a balloon catheter is placed in the descending thoracic aorta. The balloon inflates during diastole and deflates just before systole, increasing coronary perfusion and reducing left ventricular afterload. Used in certain cases of cardiogenic shock and severe heart failure. Plain language: a device with a balloon inside the main artery that inflates and deflates with the heartbeat to help the heart pump more effectively in very severe shock or heart failure.

Vasopressors

Medications that constrict blood vessels and raise blood pressure in patients with shock (e.g., norepinephrine, dopamine). Plain language: drugs given through a drip to increase blood pressure when it is dangerously low.

2. Postmortem and documentation terms Cause of Death / Certification

Death certificate

An official document completed by a physician stating that death has occurred and describing the presumed cause of death, used for legal procedures such as cremation and updating the family register. In this site, the term refers to the document usually issued when a death is considered due to natural causes or illness.

Death notification / death registration form

In the Japanese system, a form attached to the left side of the death certificate or postmortem examination certificate, on which the bereaved family (or another legally responsible person) fills in personal and administrative information about the deceased. Submission of this form to the municipal office starts official postmortem procedures (cremation permit, update of the family register, etc.). Plain language: the form that relatives submit to the local city or town office to officially register that a person has died.

Postmortem examination certificate (often translated from Japanese “shitai kenansho”)

In the Japanese context, a document issued by a physician after examining a body, especially in cases of non-natural, suspicious, or unexplained death, which records findings and provides an opinion on the cause and manner of death. Plain language: a form completed after inspecting a body, particularly when the death may not be a straightforward natural death.

Judicial autopsy / forensic autopsy

A detailed postmortem examination ordered by judicial authorities (such as police or prosecutors) to determine the cause and manner of death, especially in cases of suspicious, violent, or unexplained deaths. Plain language: an autopsy requested by authorities to investigate how and why someone died.

Pathological autopsy / clinical autopsy

An autopsy carried out primarily for medical purposes — to clarify the disease process, confirm diagnoses, and contribute to medical education and quality improvement. Plain language: an autopsy done more for medical learning and confirming diagnosis than for legal investigation.

Cremation permit

An administrative authorization allowing the body to be cremated, often issued based on a valid death certificate or postmortem examination certificate. Plain language: permission from local authorities that is required before a body can be cremated.

Removal from family register (koseki)

In Japan, the legal process of recording a person’s death in the family register, resulting in their removal from the official household record. Plain language: the formal process by which a person is legally recorded as deceased in Japan.

Classification of death (illness / accident / suicide / homicide / undetermined)

Administrative categories used in death-related documents and statistics to classify the manner of death. Suspicious or violent deaths are expected to be thoroughly investigated and correctly classified. In this case, the discrepancy between what the family observed and how the death was classified is a central issue.

3. Legal and procedural terms Japan

Evidence preservation procedure (shōko hozen)

A legal procedure in Japan in which a court orders that important evidence be preserved and formally recorded before a trial, to prevent its loss, alteration, or destruction. Plain language: a court-supervised process to secure important evidence in advance.

Criminal complaint (jiken no kōkoku / kokuhatsu)

A formal request submitted to investigative authorities (such as the police or prosecutors) asking them to investigate an alleged crime. Plain language: an official filing that says “please investigate this as a crime.”

Prosecutor / Public Prosecutors Office

The authority in Japan responsible for deciding whether to indict suspects and pursue criminal charges in court. Plain language: the public authority that decides whether to bring a case to criminal trial.

District Court

A primary court in Japan that handles a wide range of civil and criminal cases, including lawsuits related to medical malpractice. Plain language: the main trial court where serious civil and criminal cases are heard.

Medical malpractice / medical negligence

Failure by a healthcare professional to provide the standard of care that a reasonably competent practitioner would provide under similar circumstances, resulting in harm to a patient. Plain language: harmful mistakes or omissions in medical care that should not have happened.

Informed consent (IC)

A process by which a physician explains the nature, risks, benefits, and alternatives of a proposed treatment so that the patient or family can make a voluntary, informed decision. Plain language: proper explanation so that patients or families can decide about treatment with full understanding.

Do-not-resuscitate order (DNR)

A medical order indicating that cardiopulmonary resuscitation (CPR) should not be performed if the patient’s heart or breathing stops. Plain language: a decision not to attempt CPR if the heart stops or breathing ceases.

4. How to use this glossary

If you encounter an unfamiliar term while reading other pages on this site, you may return to this glossary and check the definition and plain-language explanation.

For readers with a medical background, the specialist terminology should be sufficient to understand the clinical and forensic aspects of the case. For general readers, the accompanying explanations are designed to provide context without oversimplifying the seriousness of the issues.

If you wish to delve deeper, you may also copy any term from this page into an external search engine, academic database, or AI tool to obtain further detail.