Cardioangiography and cardiac catheterization

The introduction of a catheter through an artery or vein into the heart cavity provides information on the magnitude of the pressure, the nature of the blood flow, the oxygenation of blood obtained from different chambers, and when introducing a contrast agent and subsequent cardioangiography, evaluate the morphological features. These studies make it possible to obtain high-precision information on morphological and functional changes in the heart and to solve various diagnostic, and increasingly, therapeutic problems.

For catheterization of the heart, special catheters with a diameter of 1.5-2.7 mm and 80-125 cm in length are used. To insert the catheter, the elbow vein or femoral artery is punctured with special needles. There are different versions of catheters with devices, for example, with inflatable balloons, which allow for the conduct of medical treatments. Through the catheters, a contrast agent (cardiotrast) is injected into the corresponding cavities of the heart and a series of X-ray photographs refining the morphological changes are made.

Particularly important is the coronary arteriography performed along with ventriculography in patients with ischemic heart disease. In this case, it is possible to assess and establish the presence, localization, severity and spread of coronary obstruction, as well as to assess its cause, ie, the presence of atherosclerosis, thrombosis or spasm of the coronary arteries. Hemodynamic value has a narrowing of the coronary artery by 50-75% of its lumen. The narrowing by 50% has a hemodynamic value with a sufficiently large length. A narrowing of 75% or more is important even if it is present on a short length of the vessel. Spasm of the coronary artery occurs usually on a significant length and undergoes reverse development upon the administration of nitriglycerin. With cardiac catheterization and coronary arteries, medical treatments for myocardial revascularization are currently being performed simultaneously. In myocardial infarction intracoronary injected thrombolytic agents.

With stenotic coronarosclerosis, transluminal coronary angioplasty or laser recanalization is performed. Coronary angioplasty consists in bringing to the site of constriction of the balloon, which inflates and thereby eliminates the narrowed section. Since in the future often the repeated narrowing of the same site occurs, a special plastic is made with the installation of an endoprosthesis, which is subsequently covered with intima.

Indications for coronary angiography are the need to clarify the genesis of pain in the heart and in the chest, refractory to the treatment of angina, the choice of surgery (coronaroplasty or the imposition of aortocoronary shunt). Coronary angiography is a relatively safe procedure, but complications are possible in the process, including the occurrence of a heart attack, delamination or rupture of the coronary vessel, the onset of thrombophlebitis, and neurological disorders.

With heart defects, angiocardiography allows you to refine the anatomical features, including the size of the heart chambers, the presence of regurgitation or discharge of blood, the degree of narrowing of a hole.

In the cavities of the heart, the following parameters are normally determined: pressure in the right ventricle - 15-30 mm Hg. Art. (systolic) and 0-8 mm Hg. Art. (diastolic), in the pulmonary artery - 5-30 mm Hg. Art. (systolic) and 3-12 mm Hg. Art. (diastolic), in the left atrium (as in the left ventricle) - 100-140 mm Hg. Art. (systolic) and 3-12 mm Hg. Art. (diastolic), in the aorta of 100-140 mm Hg. Art. (systolic) and 60-80 mm Hg. Art. (diastolic). Oxygen saturation of blood obtained from different chambers of the heart varies (right atrium - 75%, right ventricle - 75%, pulmonary artery - 75%, left atrium - 95-99%). By measuring the pressure in the heart cavities and by examining the saturation of blood with oxygen when it is hemmed from different chambers, it is possible to obtain more additional information about the morphological and functional changes in the riocardium. The pressure level also makes it possible to judge the contractile function of the right and left ventricles. The pulmonary capillary wedge pressure when the catheter is inserted into the pulmonary artery (as far as possible distally) reflects the magnitude of the pressure in the left atrium and in turn characterizes the diastolic pressure in the left ventricle. At a catheterization it is possible to measure rather accurately the cardiac output (liters per minute) and the cardiac index (liters per minute per 1 m ^{2 of} the body surface). This involves the introduction of a fluid of a certain temperature (thermodilution). Using a special sensor, a curve is obtained which, with a horizontal line, forms an area proportional to cardiac output. The presence of an intracardiac shunt is established when measuring the oxygen saturation of blood in the corresponding chambers of the heart.

Differences in the oxygen saturation of blood between the right atrium and the right ventricle can occur with a defect of the interventricular septum, at which the discharge of blood from left to right occurs. Given the magnitude of cardiac output, the amount of blood discharged through the shunt can be calculated. In the presence of acquired and congenital malformations, the question of tactics and the nature of surgical treatment is decided. At present, in patients with certain defects, for example mitral stenosis, surgical intervention is sometimes performed taking into account echocardiography data without catheterization. In patients with stenosis of valve openings, sometimes, instead of surgical intervention, valvuloplasty is performed using a balloon.

Continuous catheterization of the right heart and pulmonary artery with the help of a balloon floating catheter (Swan-Ganz catheter) is conducted from several hours to days. At the same time, the pressure in the pulmonary artery and in the right atrium is monitored. Indications for such a balloon catheter test are the occurrence of cardiogenic or other shock, postoperative observation of patients with severe cardiac pathology, and also for patients who need correction of the amount of fluid and central hemodynamics. This study is important in the differential diagnosis of pulmonary edema of the heart and non-cardiac origin, with interventricular septal rupture, papillary muscle detachment, acute myocardial infarction, and assessment of hypotension that does not change with fluid administration.

With cardiac catheterization, endomyocardial biopsy of the left or right ventricular tissue is also possible. Reliable results can only be obtained if the tissue is examined from 5-6 different parts of the myocardium. This intervention is important for diagnosing rejection of a transplanted heart. In addition, it can be used for the diagnosis of congestive cardiomyopathy and its differentiation from myocarditis (inflammatory myocardial damage), as well as for the recognition of infiltrative processes in the myocardium, for example hemochromatosis, amyloidosis.

At present, there is a continuous improvement in the technique of the study of the heart, using, for example, nuclear magnetic resonance, etc., in order to replace invasive intervention (cardiac catheterization of the heart) with non-invasive examination in many cases. An example of this is subtractive digital angiography, which consists in the introduction of a contrast agent into the vein (without catheterization) followed by an X-ray study whose data is computer processed, resulting in the production of a normal X-ray coronary argram and evaluation of the morphological state of the coronary arteries. It is possible in principle and intracardiac cardioscopy is already performed, which also allows you to visually directly assess the morphological changes in the heart.

[1], [2], [3], [4], [5], [6]