Hypertension Blog

Diagnostic testing for heart failure includes chest X-ray, ECG, echocardiography, and pulmonary artery catheterization.In a patient with heart failure, a chest X-ray reveals an enlarged heart, indicating hypertrophy or dilation. If the patient is in the early stages of heart failure, the chest X-ray may show congested pulmonary veins in the upper lobes. If he is in the late stages, the X-ray may show interstitial pulmonary edema and pulmonary effusion. If the patient has biventricular failure, the chest X-ray may show a pleural effusion.

A physician uses an ECG to detect left ventricular hypertrophy. An ECG also detects signs of arrhythmias, such as irregular QRS complexes and F waves, and signs of myocardial ischemia, such as T-wave inversion and ST-segment elevation.

Used to measure the size of the heart chambers, echocardiography may reveal an enlarged right or left atrium. This test also is used to assess ventricular function and to detect ventricular hypertrophy. With normal ventricular function, echocardiography shows concentric contractility, a lack of abnormal wall movement, and a left ventricular ejection fraction of 55% to 60%. With left ventricular hypertrophy, it displays a ventricular wall thickness that exceeds 1.2 cm during diastole.

Pulmonary artery catheters are used to measure cardiac pressures. In right ventricular heart failure, the patient’s right atrial pressure may be elevated. In left ventricular heart failure, his pulmonary artery pressure and pulmonary artery wedge pressure are elevated, and CO is reduced.

To determine if a patient has hypertension, of course, you’ll measure his blood pressure. From his blood pressure measurements, you can determine his pulse pressure and mean arterial pressure (MAP). These measurements, in turn, can help you detect related disorders and understand the effects of certain hemodynamic factors on your patient’s blood pressure.

Arterial System

Arteries, the vessels through which blood travels away from the heart, all carry oxygenated blood, except for the pulmonary arteries, which carry oxygen-depleted blood from the heart to the lungs. The arterial system is made up of vessels of various sizes:

• large, usually elastic arteries, such as the aorta and the pulmonary trunk
• medium-sized arteries, which make up most of the arterial vasculature
• large and small arterioles.

Arteries have nerves bundled along their outer walls. Primarily derived from the sympathetic nervous system, these nerves cause the arteries to contract and relax, thus regulating the flow of blood to various parts of the body.

Arterial Walls

All arteries have three distinct layers. The outer layer (tunica adventitia or externa) is made of strong connective tissue with abundant elastic fibers. The middle layer (tunica media) consists of more elastic fibers than smooth-muscle fibers. The inner layer (tunica intima) is a transparent and highly elastic structure that has direct contact with the circulating blood.

The thickness of each of these layers varies depending on the location of the artery. For instance, large arteries like the aorta or pulmonary arteries typically have a thick tunica media with more elastic fiber than smooth muscle, enabling them to stretch as blood is ejected from the heart during systole and to recoil during diastole. However, arteries located farther away from the heart have less elastic tissue and more smooth muscle. These small-sized to medium-sized vessels are muscular arteries. Together, all arteries help to maintain blood pressure throughout the high-pressure, high-resistance, low-volume arterial system.

Arteries become arterioles when the diameter of the vessel is less than 0.5 mm. The thick smooth-muscle layer of the arterioles enables them to control the flow of blood through the systemic circulatory system by means of vasodilation and vasoconstriction and push the blood through finer arterial structures, the capillaries.