Hypertension is diagnosed when systolic blood pressure is consistently elevated above 140 mm Hg or when diastolic blood pressure is above 90 mm Hg. A single elevated blood pressure finding (such as white coat syndrome) is not enough to qualify for hypertension. There are exceptions to this rule for when a physician determines that the patient has hypertensive presentation with unequivocal evidence of life-threatening end-organ damage, such as hypertensive emergency, or when blood pressure is greater than 220.125 mm Hg without end-organ damage.
In about 90-95 percent of patients with hypertension, no cause can be found. In this case, it is called essential, benign, or primary hypertension. Malignant hypertension is extremely high blood pressure that develops quickly and causes organ damage.
Untreated malignant hypertension can cause aortic dissection, pulmonary edema, myocardial infarction, heart failure, stroke, and death. Immediate medical treatment is necessary.
If hypertension is caused by another condition, it is called secondary hypertension. Secondary hypertension may be caused by any of the following:
- Diabetes mellitus
- Polycystic kidney disease
- Renovascular hypertension
- Cushing syndrome
- Glomerular disease
- Thyroid conditions
- Hyperparathyroidism
- Obesity
- Aldosteronism
- Coarctation of the aorta
- Medication
- Sleep apnea
Hypertensive heart disease is any number of heart conditions that arise due to hypertension, including heart failure, left ventricular hypertrophy, and coronary artery disease.
Hypertension causes heart failure by causing left ventricular hypertrophy (thickening of the muscular ventricle), meaning the muscle relaxation is shorter between heartbeats. This causes the body to retain fluids and sodium and increase the heart rate, as it is harder for the heart to fill with enough blood to supply the body’s organs.
Hypertension puts added pressure on the arterial walls, and over time it causes damage that makes them more susceptible to narrowing and plaque buildup. This plaque can block the coronary arteries that supply blood to the heart and deprive it of receiving enough oxygen. The plaque may lead to formation of small blood clots, which may cause myocardial infarction.
Hypertension can damage the blood vessels, including those that lead to the kidneys. If this occurs, it limits the kidneys’ ability to function. If the kidneys’ blood vessels are damaged, they will not be able to remove waste and extra fluid form the body. The kidneys also produce renin, which helps balance sodium and potassium levels in the blood and fluid levels in the body. If the kidneys are not working properly, they may release renin, which can cause blood pressure to rise even higher.
Hypertension is the second leading cause of kidney failure in the United States (diabetes is the leading cause).
In the second installment, Rhonda Buckholtz discusses the complexities of coding hypertension in ICD-10.
