Saturday, July 21, 2012
Singapore - About that pain in the chest
They both had chest pain last month. Mr A was a middle-aged man with recent chest discomfort who had called up from overseas on Wednesday for an appointment on Saturday. He had intended to fly in on Friday but unfortunately, he never made it as he died of a sudden heart attack on Friday.
The stars were shining brighter for Mr B. He had exertional chest discomfort for the last two months and finally decided to come for an assessment of his heart a fortnight ago. Tests performed confirmed the presence of significant blockage of all the three major arteries of the heart.
Ever so often, when you are jogging, playing your game of tennis or while you are enjoying your game of golf, you may have felt that discomfort in the chest and you are wondering whether to dismiss it or take it as a warning of underlying heart disease. This is a common dilemma.
Chest pain is the most common complaint encountered by family physicians, cardiologists and emergency-room physicians. What distinguishes the chest pain due to underlying blockage of the heart arteries (angina pectoris) from other types of chest pain are the characteristics of the pain.
The term angina pectoris is derived from the Latin word angina ("infection of the throat"), the Greek ankhone ("strangling"), and the Latin pectus ("chest"), and can therefore be translated as "a strangling feeling in the chest".
Typically, it is described as tightness over the central or left anterior chest, which may occasionally radiate down the left arm. It is aggravated by physical exertion and relieved by rest. Occasionally, it presents itself as increasing shortness of breath or neck tightness on physical exertion without any chest pain.
The heart muscle receives blood through three major heart (coronary) arteries which carry oxygenated blood to the heart muscle cells (myocytes). During rest, the myocytes take up about 75 per cent of the oxygen content that is present in the blood flowing through the heart arteries. Hence, during exercise, the increased demand for oxygen is met primarily through increased blood flow through the heart arteries. If there is an obstruction to blood flow as a result of narrowing of the heart arteries, the oxygen supply may be unable to meet the increased demand, resulting in an environment where there is insufficient oxygen. This results in the activation of cellular pathways which operate in an oxygen-scarce environment, resulting in the production of chemicals such as lactic acid. The build-up of these chemicals stimulate nerve endings that cause the sensation of pain.
Angina or heartburn?
Heartburn is an uncomfortable feeling of burning or warmth in the central chest, which may radiate to the neck, throat and jaw. It can mimic angina and present itself as chest tightness. Unlike angina, it is not due to heart disease, but is a result of backflow of acid from the stomach into the oesophagus. It is typically aggravated by lying down or bending over soon after a meal and relieved by standing up, drinking water and taking antacids. It is present in about one-third of adults, especially in pregnant women. It can sometimes be difficult to distinguish it from angina, the main distinguishing factor being that heartburn is not related to exertion.
Angina in the young
Angina can occur in the young as a result of inherited conditions. While the major heart arteries of the heart lie on the surface of the heart in the majority, in some, the artery may take a course where a segment of the artery may be embedded in the heart muscle (myocardial bridging) and hence the embedded segment may be compressed by the heart muscle bands during contraction of the heart. If a long segment is embedded deeply into the heart muscle, the obstruction to flow may be significant enough to cause angina during vigorous physical exertion.
Another rare cause of mechanical obstruction is the abnormal origin and course of the heart artery, where a segment of it is wedged between the main artery arising from the heart (aorta) and the lung artery (pulmonary artery). During heavy physical exertion, the pulsations of the two large arteries may result in compression of the heart artery to the extent that it causes angina. On rare occasions, these two inherited causes of heart artery obstruction can cause sudden death during vigorous physical exertion in the young.
Angina not related to exertion
While angina is typically associated with physical exertion, there is an uncommon variety called coronary vasospasm or Prinzmetal's angina. This condition is due to transient constriction of the heart artery secondary to abnormalities in the regulation of the smooth muscle in the wall of the artery.
Mdm C had typical angina except that it was not related to exertion and she had a negative stress test for heart disease. Her diagnosis was eventually confirmed when she recorded her electrocardiogram (electrical pattern of heart or ECG) with a portable ECG monitor during angina. The recorded ECG resembled an acute heart attack and was associated with life-threatening heart rhythms.
The confirmation of coronary vasospasm allowed the institution of measures that averted the possibility of sudden death.
Chest pain but not angina
Understanding angina will help to distinguish the types of chest pain that do not need urgent medical attention. Chest pain is usually not angina if it can be localised to a single site on the chest using two fingers, is sharp, pulling or pinprick in nature, and not aggravated by exertion.
However, if you have risk factors for heart disease and have a family history of heart disease, do remember that having no chest pain does not mean there is no heart disease. After all, about 70 per cent of the patients who arrived at the emergency department with an acute heart attack never had chest pain previously.
Dr Lim is medical director at the Singapore Heart, Stroke & Cancer Centre. He is also editor-in-chief, Heart Asia (a journal of the British Medical Journal Publishing Group); chairman, scientific advisory board, Asia Pacific Heart Association; and honorary professor and senior medical adviser, Peking University Heart Centre.
This series is brought to you by the Heart, Stroke and Cancer Centre. It is produced on alternate Saturdays.
Dr Michael Lim
The Business Times