How are stroke and heart disease related? Cardiology Basics

How are stroke and heart disease related? Cardiology Basics

Ischemic stroke is often due to sudden obstruction to a cerebral artery which usually results in paralysis. Hemorrhagic stroke is due a bleed from a cerebral vessel and deemed to be more dangerous than ischemic stroke.

Stroke and heart disease are linked together in various ways. In general, risk factors for stroke and ischemic heart disease are similar. Ischemic strokes can sometimes occur simultaneously with an acute myocardial infarction.

Stroke can occur after a myocardial infarction as well. Myocardial infarction can cause damage to a region of endocardium over the infarct. This region can be a nidus for the formation of a left ventricular thrombus.

Left ventricular mural thrombus occurring as a complication of myocardial infarction can break off and embolize to the cerebral vessels. Thus it can cause an embolic stroke. Thrombi can also form in the left atrium in the presence of mitral stenosis. Mechanical heart valves can also be a source of thromboembolism.

Atrial fibrillation is another reason for an embolic stroke. In atrial fibrillation, the activation of the atria is so fast that effective contraction is not possible. This leads to sluggish flow and cause thrombus formation, especially in the left atrial appendage.

Thrombi from the left atrium can break away and embolize to the cerebral vessels causing stroke. That is why anticoagulation is given to prevent stroke when there is atrial fibrillation along with other risk factors. Anticoagulation is also needed prior to cardioversion of atrial fibrillation which has persisted more than 48 hours, due to risk of embolization on restoration of sinus rhythm. An alternate method is to exclude left atrial thrombi by transesophageal echocardiography prior to urgent cardioversion.

Another reason for stroke is hypertension. Acute onset of severe hypertension can lead to rupture of small cerebral vessels and cerebral hemorrhage. That is why acute rise in blood pressure if detected, should be urgently controlled. But control need not be to normal levels as it might upset the cerebrovascular autoregulation in a hypertensive person. Initial reduction from very high levels followed by a more gradual reduction to near normal levels may be better if the person is known to be a hypertensive.

Even without a bleed, cerebral function can be altered due to acute rise in blood pressure, causing altered sensorium. Then that is not a stroke but a hypertensive encephalopathy.