Angina pectoris caused by extracoronary diseases

Chest pain can arise from cardiovascular or noncardiovascular causes. Among the latter are the skin, the chest wall, intrathoracic structures, or subd iaphragmatic organs. The problem to attribute the chest discomfort to eithe r the heart or extracardiac organs arises because the heart, pleura, aorta, and esophagus are all supplied by sensory fibers from the same spinal segm ents. In contrast to the diseases mentioned above, angina pectoris in sensu stric tu is defined as chest pain or discomfort of cardiac origin that arises bec ause of temporary imbalance between myocardial oxygen supply and demand. Th e metabolic oxygen requirements of the myocardium are essentially dictated by myocardial contraction since only a fraction of the consumed oxygen is n eeded by the quiescent heart. Therefore, the factors that primarily influen ce myocardial oxygen consumption include heart rate, the force of cardiac c ontraction, and myocardial wall tension, as determined by pressure (afterlo ad), volume (preload), and wall thickness. Extracoronary diseases, e. g. hy pertensive heart disease, aortic stenosis or cardiomyopathies, can influenc e these factors and induce angina pectoris (Figure 1). On the other hand, d ifferent diseases influencing the oxygen supply, e. g. anemia, can cause an gina pectoris, too. In addition, the modulation of the coronary tone by med iators and cytokines can cause angina, coronary spasm being one example. The neurophysiological substrate of angina pectoris are ganglia which are p resent within the heart, particularly in epicardial fat. The sympathetic ne rvous system is the main conveyer of afferent pain fibers from the heart an d pericardium, but many fibers may travel by the vagus and the phrenic nerv es. Therefore, multiple thoracic structures may cause similar pain syndrome s in the distressed patient. The blood supply of intrinsic cardiac ganglia arises primarily from branches of the proximal coronary arteries. Adenosine . among a number of substances, can modulate the activity generated by card iac afferent nerve endings and intrinsic cardiac neurones. During myocardia l ischemia adenosine is released in large quantities into the interstitial space. Given as an intravenous bolus to healthy volunteers or to patients w ith ischemic heart disease and angina pectoris, adenosine provokes angina p ectoris-like pain, which is similar to habitual angina pectoris with regard to quality and location. But other mediators (e. g. bradykinin, histamine, prostaglandins, potassium, lactate) can be involved in the development of angina pectoris, too. As most emphasis should be given to the most serious causes first, the card iologist has to consider ischemic cardiac disease in the differential diagn osis of nearly every case of acute chest pain. The differential diagnosis c ontains several causes of nonischemic cardiac chest pain. Dissecting aortic aneurysm may cause severe anterior chest pain that can be mistaken for myocardial infarction. Patients frequently will note the sudd en onset of the pain rather than the relatively slower onset of ischemic pa in. Furthermore, they feel as a tear and describe it as the most severe pai n they have ever had. Pericarditis can be characterized as a sharp precordial knifelike pain that is often increased by lying down, breathing, swallowing, or any other thor acic motion. Radiation of pericardial pain is often relieved by sitting up or leaning forward. It may involve the shoulders, upper back, and neck beca use of the irritation of the diaphragmatic pleura. Acute pulmonary embolism is associated with severe chest pain. It may mimic acute myocardial infarction. Pulmonary embolism should be suspected when d yspnea or tachypnea seems to be disproportionate to the severity of the che st pain. Diffuse esophageal spasm is the extracardiac condition that is confused mos t often with ischemic cardiac chest pain. This pain presents as a deep thor acic pain that may be present over most of the thorax. It may extend down t he anteromedial side of the arms and forearms. It may be relieved by nitrat es, making it even more confusing. Emotional disorders are among the most common causes of chest pain. Usually the discomfort is described as tightness or aching. Because the pain is of ten midsternal in location and because it can be quite severe, it can be co nfused with ischemic chest pain. Many times, the history can be helpful in differentiating this pain. Chest pain may come from various muscle and ligament injuries in the chest wall. Costochondritis is a fairly common cause of anterior chest pain. Othe r causes include cervical or thoracic osteoarthritis, ruptured cervical dis ks, or compression of the neurovascular bundle by a cervical rib or shorten ed anterior scalene muscle. The treatment of angina pectoris induced by extracoronary diseases must be a therapy of the extracoronary disease first. But it is worth mentioning th at often extracoronary induced angina pectoris is accompanied by non-signif icant coronary artery stenosis.