17.11
Angina I: Introdução
Definição e Sintomas: A angina (angina pectoris) é uma dor ou desconforto no peito causado por isquemia miocárdica, que ocorre quando o músculo cardía…
Angina, ou angina de peito, é dor ou desconforto no peito causado por isquemia miocárdica, na qual o músculo cardíaco recebe sangue rico em oxigênio insuficiente.
Normalmente parece pressionar, apertar ou esmagar o peito, muitas vezes irradiando para os ombros, braços, pescoço, mandíbula ou costas.
A principal causa de angina é a aterosclerose, onde o acúmulo de placas estreita as artérias coronárias, reduzindo o suprimento de sangue rico em oxigênio para o músculo cardíaco.
Outros fatores contribuintes incluem espasmos da artéria coronária, doença microvascular e condições que aumentam a demanda de oxigênio do miocárdio, como hipertrofia ventricular esquerda ou taquicardia.
Os fatores de risco que contribuem para a angina incluem hipertensão, hiperlipidemia, tabagismo, diabetes, obesidade, estresse, sedentarismo, má alimentação, idade avançada e história familiar de doença arterial coronariana.
A fisiopatologia da angina é devida a um desequilíbrio entre a oferta e a demanda de oxigênio do músculo cardíaco.
Durante o aumento da atividade física ou estresse, a demanda do coração por oxigênio supera o suprimento restrito devido ao estreitamento das artérias coronárias, levando à isquemia e dor anginosa.
View the full transcript and gain access to JoVE Core videos
Q1: What is angina and what does it feel like?
Angina, or angina pectoris, is chest pain or discomfort caused by myocardial ischemia, when the heart muscle receives insufficient oxygen-rich blood. It typically feels like pressing, squeezing, or crushing sensations in the chest and may radiate to the shoulders, arms, neck, jaw, or back.
Q2: What causes angina to develop?
The primary cause of angina is atherosclerosis, where plaque buildup narrows the coronary arteries, reducing oxygen-rich blood flow to the heart muscle. Contributing factors include coronary artery spasms, microvascular disease, and conditions that increase myocardial oxygen demand, such as left ventricular hypertrophy or tachycardia.
Q3: How does myocardial ischemia lead to anginal pain?
Angina results from an imbalance between the heart muscle's oxygen supply and demand. During increased physical activity or stress, the heart's demand for oxygen surpasses the restricted supply due to narrowed coronary arteries, leading to ischemia and anginal pain. This oxygen deficit triggers chest discomfort.
Q4: What physical and emotional factors trigger angina?
Physical activity such as walking, running, or climbing stairs increases the heart's workload and oxygen demand. Emotional stress can also increase heart rate and blood pressure, raising oxygen demand. Narrowed coronary arteries cannot deliver sufficient oxygen-rich blood to meet these increased demands, triggering angina.
Q5: What are the main risk factors for developing angina?
Risk factors include hypertension, hyperlipidemia, smoking, diabetes, obesity, stress, physical inactivity, poor diet, increasing age, and family history of coronary artery disease. These factors contribute to atherosclerosis and narrowing of coronary arteries, significantly increasing the risk of developing angina symptoms.
Q6: How do healthy coronary arteries differ from those affected by coronary artery disease?
In a healthy state, coronary arteries can dilate to increase blood flow and meet increased oxygen demand during physical activity or stress. In coronary artery disease, narrowed coronary arteries limit the ability to increase blood flow during increased oxygen demand, leading to ischemia and angina.
Q7: What role do microvascular disease and coronary artery spasms play in angina?
Microvascular disease affects small blood vessels in the heart, reducing blood flow and causing angina. Coronary artery spasms cause sudden, temporary narrowing of coronary arteries, also reducing blood flow and oxygen delivery. Both conditions contribute to myocardial ischemia and anginal symptoms in susceptible patients.