Renal infarction is a vascular occlusion in the kidneys that affects the blood flow and oxygen supply to the kidney tissue, causing the tissue to die as a result. The most common causes of this ischemic phenomenon are thrombosis and embolism. Complete renal infarctions may later force the patient to undergo dialysis, whereas the kidneys often recover completely from partial infarctions.
What is a renal infarction?
A renal infarction is the term physicians use to describe the loss of kidney tissue as a result of embolic vessel occlusion. The kidney has many arteries running through it and is supplied with oxygen through this arterial system. When there is an occlusion in the arterial vascular system, the tissue is cut off from blood supply and thus doomed to die in the long run. This phenomenon is also known as ischemia, so that in the case of a renal infarction, the term is often used to refer to an ischemic reaction. Often the physician also speaks of an embolic renal infarction. Embolism in this context means an arterial occlusion by foreign or endogenous materials. The site of onset of a renal infarction is usually the renal capsule with its blood-bearing structures. Sometimes renal infarction also refers to venous occlusion, which can result in a hemorrhagic, or bleeding, infarction of the kidney, permanently distending the kidneys. To be distinguished from this is anemic renal infarction, which does not expand the organs but deforms them by scar tissue with craters. In addition to differentiating between causes, physicians differentiate renal infarction primarily by the type of occlusion. Complete occlusion corresponds to absolute ischemia and causes the kidney tissue to die completely as a result. Incomplete occlusion in an arterial vessel results only in local decreased perfusion.
Causes
Blockage of a renal artery or vein can basically have a variety of causes; however, renal infarctions are more than 90 percent emboli. Embolism can occur because of an engulfed blood clot, but engulfed fat or bubble formation in the blood are also among embolic causes. In cancer patients, washed-in tumor tissue can also trigger an embolism. Cholesterol embolisms, in turn, are caused by dissolved plaques of an arterial wall, while septic embolisms are caused by bacterially infected emboli. Most often, however, the cause of embolic renal infarction is an engulfed blood clot from the aorta or the heart wall, where thrombosis has previously occurred. This phenomenon may also be related to arteriosclerosis or vasculitis. Hemorrhagic renal infarcts, on the other hand, usually result from circulatory shock, with thrombosis forming in the renal vein itself due to a slowing of blood flow. Diseases of the connective tissue, vascular disease, and heart disease and vascular injury are considered the most important risk factors for renal infarction.
Symptoms, complaints, and signs
A typical symptom of renal infarction is acute onset flank pain. Depending on the severity of the infarction, this pain may be joined by a sharp abdominal pain. Nausea, fever, and vomiting also occur symptomatically. Serum may show a concomitant increase in leukocytes. Days after renal infarction, acute renal failure may develop, often manifested by hemorrhage on urination. If arteriosclerotic material is responsible for the infarction in the case of an embolic cause, then this material can also be deposited in other organs or body components in the further course. Therefore, symptoms of renal infarction may include visual field defects or inflammation of various localizations. Partial renal infarctions in particular often remain completely asymptomatic. Although functional impairments of the kidney can also occur in partial infarctions, these impairments do not have to become apparent immediately.
Diagnosis and course of the disease
History and palpation provide the physician with initial clues to a possible renal infarction. The quality of the flank pain, in combination with the patient’s vascular disease, for example, may already lead him to suspect a renal infarction. He often examines the serum, which may also show elevated creatine and an increase in leukocytes.The physician usually makes the final diagnosis of a renal infarction via angiography or computed tomography. In this imaging, the infarct usually shows a relatively typical image, and this also enables differentiation into partial or complete infarction. Under certain circumstances, the attending physician may order a sonographic examination of all arteries and veins after the diagnosis has been made, which may provide evidence of previous thromboses or show calcified vessel walls. Examinations of the heart may also be useful to rule out cardiac dysfunction as a source of renal infarction. The course of the disease in renal infarction always depends on how severe and how long-lasting the infarction has actually been. For cholesterol embolic renal infarcts, the prognosis is generally poor. In this case in particular, the patient may require dialysis in the future. Partial renal infarcts, on the other hand, often heal completely.
Complications
The course of a renal infarction depends on the duration and extent of the blood supply to the kidneys. In about 25 percent of cases, the infarction even progresses without symptoms because only smaller areas of the kidney die. If necrosis of larger areas of the kidney occurs, acute kidney failure may develop under certain circumstances. The prognosis is particularly poor in the case of a so-called cholesterol embolism, which usually results in renal insufficiency requiring dialysis. In acute renal failure, the end products of protein metabolism and all other urinary substances remain in the blood. In addition, the electrolyte balance gets completely out of whack. The same applies to the acid-base balance. Uremia, a life-threatening state of poisoning, can develop. Uremia is characterized by the increased occurrence of uremic substances in the blood, which is also called “urine in the blood” in Greek. In addition to an unbearable itching, nausea, vomiting and black blood in the stool occur as a result of inflammation of the gastric mucosa and intestines. Furthermore, pulmonary edema, dyspnea and cyanosis occur. Excessive urea in the blood can cause pathological changes in the brain and other neurological disorders. The regenerative capacity of the kidneys after acute renal failure due to renal infarction is good. However, sometimes permanent kidney damage requiring dialysis occurs, as mentioned above. In individual cases, fatal multiorgan failure may also occur because of secondary impairment of various organs.
When should you see a doctor?
Renal infarction is always a reason to see a doctor as soon as possible. An emergency department is preferable, as a moderate to very severe infarction requires acute treatment. A complete renal infarction can mean the end of the entire kidney, which makes seeing a doctor all the more urgent. But even a partial occlusion of a blood vessel on or in the kidney can lead to severe necrosis after some time and permanently damage or kill the kidney. If only one functioning kidney is left, or if both are affected, kidney failure will result if timely action is not taken. In this context, it is problematic that minor kidney infarctions often do not cause any symptoms and therefore only cause hidden damage. It is often only the late effects that are noticed. In the case of renal infarctions, therefore, the smallest signs of kidney damage should be taken as a reason to go to the doctor (or, if necessary, to a hospital). These include, in particular, acute and severe pain in the flanks and brownish or reddish discolored urine. The pain in particular must also be diagnosed because it indicates several conditions. For example, kidney stones, colic or inflammation can also be detected. People who already have kidney restrictions, have a transplant, or have only one (functioning) kidney should have any possible indication of an infarction checked.
Treatment and therapy
In most cases, renal infarcts are treated conservatively. Administration of analgesics and regulation of blood pressure are part of this conservative therapy, as is systemic full heparinization. The latter measure is equivalent to administration of an anticoagulant to dissolve any blood clots.Depending on the severity of the infarction and how early the physician was able to make the diagnosis, lysis therapy or emergency surgery may also be considered, which may still be able to dissolve an existing embolus. Since operations for this purpose are associated with a high risk, they are used less frequently than lysis therapies. In lysis therapy, the physician inserts a catheter up to the existing blood clot and triggers dissolution of the clot by releasing enzymes such as urokinase. Dialysis can also be useful for acute kidney infarctions. This measure does not necessarily say that the kidneys will not recover in the course.
Outlook and prognosis
The prognosis for renal infarction depends on the severity and duration of decreased renal blood flow. Complete recovery of the affected kidney is possible, as is complete renal failure. If a renal infarction remains untreated, it is fatal. The prognosis is particularly poor for renal infarction associated with cholesterol embolism. Patients are then usually required to undergo dialysis. However, renal recovery is possible even with temporary dialysis. A good prognosis depends on prompt diagnosis and treatment of the renal infarction. If the condition is treated at an early stage, for example when the typical flank pain first appears, complete organ infarction may be prevented. The prognosis for a renal infarction is determined by the internal medicine specialist in charge. In most cases, the treating physician is a nephrologist, who takes into account the symptoms and the severity of the renal infarction, among other factors, to evaluate the course of the disease. A renal infarction with subsequent dialysis requirement has a negative effect on life expectancy, since dialysis increases the risk of infection, among other things. In the case of a positive course, the life expectancy of the sufferer is not necessarily limited. Quality of life may be significantly reduced as a result of a damaged kidney.
Prevention
To prevent renal infarction, lifestyle changes are beneficial. The focus of preventive measures is on reducing the risk of arterial calcification. Abstaining from nicotine and eating a healthy diet are good preventive measures in this regard, as are abstaining from alcohol, reducing weight, and exercising.
Follow-up
Because a renal infarction can have varying degrees of severity, dutiful follow-up care is useful. Those affected can largely take charge of this themselves by changing their habits and everyday life for the better. The first priority is the strengthening and complete recovery of the body. This can be achieved with the help of various measures. An important aspect in any case is an adequate supply of oxygen and an appropriate amount of exercise that does not overstrain the body. If possible, this should take place outdoors so that a healthy amount of fresh air can reach the body. Furthermore, at least two liters of water should be drunk daily, which will revive the activity of the kidneys. The intake of harmful substances such as alcohol, drugs or nicotine, should be completely avoided. In addition, attention should be paid to a balanced, low-fat and all-around healthy diet. If necessary, excess weight should be reduced in order to spare the organism unnecessary energy-sapping expenditure. Since both the physical and mental state play a role in complete recovery, attention should also be paid to mental strain and stress. In order to effectively reduce such ailments and emerging stress, meditation, relaxation and regular rest are of tremendous importance.
This is what you can do yourself
In many patients, a renal infarction passes without symptoms for a long period of time. Therefore, basic precautionary measures that strengthen the organism are advisable. An adequate supply of oxygen is helpful. Regular exercise or time spent outdoors can support the activity of the heart muscle. Physical overexertion or intense exertion should be avoided. In addition, regular breaks should be taken so that the organism receives sufficient rest. The intake of harmful substances such as alcohol, nicotine or drugs should be completely avoided. For an optimal supply of the organism, a fluid intake of two liters daily is advisable.A fatty diet or the consumption of foods that are difficult to digest should be avoided. With a healthy and balanced diet, the body receives enough nutrients to stabilize the immune system and promote overall health. Stress and hectic activity should also be reduced. Methods such as yoga, autogenic training or meditation can be used to reduce internal stress factors. Self-responsible, the affected person has the opportunity to complete a few exercise units daily and thus strengthen his inner forces. Also helpful are a positive attitude to life and individual measures to improve well-being. Since renal infarction can have a fatal course, a doctor should be consulted immediately in the event of complaints or deterioration in health, despite all precautionary measures.
