Many women feel anxious during pregnancy with symptoms that can include heart palpitations, which together with some shortness of breath (dyspnea) that also can occur during pregnancy makes some wonder if they are suffering a heart attack. More generally, you may be wondering whether a heart attack can occur during pregnancy. The answer is yes, that it can occur, although fortunately it’s rare in pregnant women with with no health problems. Even so, heart conditions during pregnancy have been on the rise in recent years, due to increasing numbers of older women getting pregnant, and due to increasing prevalence of obesity and type 2 diabetes among women of reproductive age. So let’s discuss heart attacks, the common language term that encompasses a family of cardiac events that doctors call acute coronary syndrome (ACS).
ACS is subdivided into two broad categories: non-ST elevation-acute coronary syndrome (NSTE-ACS) and ST elevation myocardial infarction (STEMI). The first category, NSTE-ACS consists of two severity types – non-STEMI (NSTEMI) and unstable angina, which used to be two completely separate categories, but are grouped together now, because they exist along a spectrum of disease with much overlap between them. As for the STEMI category, this is the most severe type of ACS, the type that requires invasive treatment.
The term infarction refers to the death of tissue in a particular region, due to the blood supply being inadequate in supplying the affected region with oxygen and other consumables. In the heart, most of the needed blood flow is to supply what’s called the myocardium. Thickest of the layers of tissue that form the heart, the myocardium consists of muscle cells. ACS occurs because of problems with the wall of one or more arteries supplying the myocardium. This results in a plaque on the inner layer of the artery, which can start to obstruct blood flow and cause a blood clot (thrombus) which further obstructs blood flow. The increasing amount of obstruction, from slight to completely across the artery, correlates with the severity of ACS and with the amount of damage to the heart muscle supplied by the affected artery.
Along with risk factors that can reduce the supply of blood to an area of the heart, such as rising age of mothers and increasing prevalence of obesity and type 2 diabetes, ACS also can occur as a result of increased demand for blood supply during pregnancy in combination with anemia. Usually, anemia of pregnancy is mild, but if severe, it’s possible for anemia to cause ACS by making it difficult for the blood system to meet the needs of the heart, even if none of the coronary arteries is obstructed.
Doctors can get an initial clue that you may be suffering from ACS, if you experience classic symptoms, namely feelings of pressure or pain in the chest and dyspnea (breathing difficulty). Pregnancy can confuse this classic presentation, but the mere possibility that you may be experiencing a heart attack will trigger a diagnostic workup that includes blood tests for looking for high levels of what are called cardiac biomarkers (cardiac muscle enzymes), particularly troponins (a group of proteins). Doctors will also order electrocardiography (ECG). In ECG, the change in voltage (electrical potential) over time that occurs across the heart is measured from different directions. By finding various subtle abnormalities in the signals as measured from different directions, cardiologists can determine, not only if you have suffered ischemia (starving of tissue, due to insufficient blood flow) or infarction (death of tissue), but also learn about the nature and location of the infarction, and whether it has affected the tissue all the way through the muscle layer.
Subsequently, there are more specialized procedures that can be performed to locate the problem and to determine its severity and whether it requires an immediate invasive treatment. A diagnosis of NSTE-ACS generally means that the progression of the condition can be stopped by giving you various medications, as long as the condition remains limited to NSTE-ACS and does not worsen into STEMI. In contrast, STEMI requires immediate intervention with reperfusion (reestablish circulation of blood) of the affected parts of the heart. This means either removing the obstruction from the blocked artery or arteries, or detouring blood around the obstruction.
The first option, opening the blocked artery or arteries can be achieved through what is called percutaneous coronary intervention (PCI). In this procedure, a stent (a tube that holds the artery open from the inside, providing a tunnel for the blood) is placed in the affected region of the affected artery/arteries. Not all hospitals have the capability to perform PCI and there are rules about how much time it takes to transport a patient to a PCI facility that determine whether PCI will be done (we are talking about an hour or two, depending on whether you are counting from which event to which event). If it is not possible to get the patient to PCI within the prescribed amount of time, then doctors can give a very powerful medication that is better avoided during pregnancy, but if it’s the only way to save the mother’s life, it must be given anyway.
If there is time to get the woman to the a PCI facility, at the hospital or at another hospital, the decision on whether or not PCI can be the treatment (or whether it can be the only treatment) also depends on the number and location of the obstructed arteries. To view the arteries of the heart and the obstructions within them, imaging is needed that exposes you to ionizing radiation. Efforts are made to minimize radiation exposure to the fetus, but not having the procedure at all will do much more harm to the fetus, since avoiding treatment can mean death for the mother, and consequently for the fetus. If the arteries cannot be stented, if too many arteries are obstructed, or if a main coronary artery is obstructed, then the patient would need a surgical procedure called coronary artery bypass grafting (CABG, pronounced like the vegetable cabbage).
In CABG, surgeons remove parts of blood vessels from other parts of the patient’s body and transplant them into the heart in a way that bypasses the blood around the obstructed portion of each affected artery and delivers the blood back into the affected artery downstream from the obstruction. During this time, your heart must be stopped from beating and opened up. To keep your brain and the rest of your body alive during this time, blood is detoured away from the heart and lungs, through what’s called cardiopulmonary bypass, a machine that pumps the blood in and out of the body, adding oxygen to the blood, and removing carbon dioxide, while the blood moves through the machine.
Unlike PCI, which does not require opening of the chest and which usually is performed with patients under just conscious sedation (the patient is awake), CABG is a major surgical procedure in which the chest is opened and the patient must have general anesthesia. This is not particularly good for the fetus, but the procedure is performed as a matter of life and death for the mother.