Other and unspecified disorders of circulatory system (I99)

The ICD-10 code I99 and its subcategories identify various other and unspecified disorders of the circulatory system that do not fit into more specific diagnostic groups. These codes help classify rare or less clearly defined cardiovascular conditions for accurate diagnosis and billing.

The code I99.8 covers a wide range of specific circulatory disorders including acute and chronic ischemias affecting limbs and organs, vascular graft complications, and inherited vascular anomalies. Terms like "limb ischemia," "arterial ischemia," and "vascular calcification" are included within this category, guiding medical coders to use I99.8 for these less common vascular conditions. On the other hand, I99.9 is used for unspecified circulatory system disorders where the exact nature is unclear; this includes broad conditions such as "vascular disorder," "cardiovascular abnormality due to anomalous origin," and "vascular disease of the abdomen." Recognizing synonyms linked to these codes aids in selecting the correct ICD-10 code for ambiguous or rare cardiovascular diagnoses, ensuring precise clinical documentation and reporting.

Clinical Terms

The following clinical terms provide additional context, helping users better understand the clinical background and common associations for each diagnosis listed in this section. Including related terms alongside ICD-10-CM codes supports coders, billers, and healthcare professionals in improving accuracy, enhancing documentation, and facilitating research or patient education.

Brain Ischemia

Localized reduction of blood flow to brain tissue due to arterial obstruction or systemic hypoperfusion. This frequently occurs in conjunction with brain hypoxia (HYPOXIA, BRAIN). Prolonged ischemia is associated with BRAIN INFARCTION.

Chronic Limb-Threatening Ischemia

A severe form of peripheral artery disease in which a hypoperfusion of the BLOOD through an organ or tissue is caused by occlusion of peripheral arterial vessels. It is associated with the presence of chronic ischemic rest pain, ulceration or GANGRENE.

Cold Ischemia

The chilling of a tissue or organ during decreased BLOOD perfusion or in the absence of blood supply. Cold ischemia time during ORGAN TRANSPLANTATION begins when the organ is cooled with a cold perfusion solution after ORGAN PROCUREMENT surgery, and ends after the tissue reaches physiological temperature during implantation procedures.

Hypoxia-Ischemia, Brain

A disorder characterized by a reduction of oxygen in the blood combined with reduced blood flow (ISCHEMIA) to the brain from a localized obstruction of a cerebral artery or from systemic hypoperfusion. Prolonged hypoxia-ischemia is associated with ISCHEMIC ATTACK, TRANSIENT; BRAIN INFARCTION; BRAIN EDEMA; COMA; and other conditions.

Ischemia

A hypoperfusion of the BLOOD through an organ or tissue caused by a PATHOLOGIC CONSTRICTION or obstruction of its BLOOD VESSELS, or an absence of BLOOD CIRCULATION.

Ischemic Attack, Transient

Brief reversible episodes of focal, nonconvulsive ischemic dysfunction of the brain having a duration of less than 24 hours, and usually less than one hour, caused by transient thrombotic or embolic blood vessel occlusion or stenosis. Events may be classified by arterial distribution, temporal pattern, or etiology (e.g., embolic vs. thrombotic). (From Adams et al., Principles of Neurology, 6th ed, pp814-6)

Mesenteric Ischemia

Ischemic tissue injury produced by insufficient perfusion of intestinal tissue by the MESENTERIC CIRCULATION (i.e., CELIAC ARTERY; SUPERIOR MESENTERIC ARTERY; INFERERIOR MESENTERIC ARTERY; and MESENTERIC VEINS). It can progress from ISCHEMIA; EDEMA; and GANGRENE of the bowel wall to PERITONITIS and cardiovascular collapse.

Myocardial Ischemia

A disorder of cardiac function caused by insufficient blood flow to the muscle tissue of the heart. The decreased blood flow may be due to narrowing of the coronary arteries (CORONARY ARTERY DISEASE), to obstruction by a thrombus (CORONARY THROMBOSIS), or less commonly, to diffuse narrowing of arterioles and other small vessels within the heart. Severe interruption of the blood supply to the myocardial tissue may result in necrosis of cardiac muscle (MYOCARDIAL INFARCTION).

Optic Neuropathy, Ischemic

Ischemic injury to the OPTIC NERVE which usually affects the OPTIC DISK (optic neuropathy, anterior ischemic) and less frequently the retrobulbar portion of the nerve (optic neuropathy, posterior ischemic). The injury results from occlusion of arterial blood supply which may result from TEMPORAL ARTERITIS; ATHEROSCLEROSIS; COLLAGEN DISEASES; EMBOLISM; DIABETES MELLITUS; and other conditions. The disease primarily occurs in the sixth decade or later and presents with the sudden onset of painless and usually severe monocular visual loss. Anterior ischemic optic neuropathy also features optic disk edema with microhemorrhages. The optic disk appears normal in posterior ischemic optic neuropathy. (Glaser, Neuro-Ophthalmology, 2nd ed, p135)

Reperfusion Injury

Adverse functional, metabolic, or structural changes in tissues that result from the restoration of blood flow to the tissue (REPERFUSION) following ISCHEMIA.

Spinal Cord Ischemia

Reduced blood flow to the spinal cord which is supplied by the anterior spinal artery and the paired posterior spinal arteries. This condition may be associated with ARTERIOSCLEROSIS, trauma, emboli, diseases of the aorta, and other disorders. Prolonged ischemia may lead to INFARCTION of spinal cord tissue.

Vascular Calcification

Deposition of calcium into the blood vessel structures. Excessive calcification of the vessels is associated with ATHEROSCLEROTIC PLAQUES formation particularly after MYOCARDIAL INFARCTION (see MONCKEBERG MEDIAL CALCIFIC SCLEROSIS) and chronic kidney diseases which in turn increase VASCULAR STIFFNESS.

Vertebrobasilar Insufficiency

Localized or diffuse reduction in blood flow through the vertebrobasilar arterial system, which supplies the BRAIN STEM; CEREBELLUM; OCCIPITAL LOBE; medial TEMPORAL LOBE; and THALAMUS. Characteristic clinical features include SYNCOPE; lightheadedness; visual disturbances; and VERTIGO. BRAIN STEM INFARCTIONS or other BRAIN INFARCTION may be associated.

Visceral Pain

Pain originating from internal organs (VISCERA) associated with autonomic phenomena (PALLOR; SWEATING; NAUSEA; and VOMITING). It often becomes a REFERRED PAIN.

Warm Ischemia

A tissue or organ remaining at physiological temperature during decreased BLOOD perfusion or in the absence of blood supply. During ORGAN TRANSPLANTATION it begins when the organ reaches physiological temperature before the completion of SURGICAL ANASTOMOSIS and ends with reestablishment of the BLOOD CIRCULATION through the tissue.