Pathology of the Circulatory System

Physiological norm and system components

Normally, the physiological state of the circulatory system implies optimal and uninterrupted supply of organs and peripheral tissues with adequate blood supply. For this complex mechanism to function smoothly, the coordinated work of several key components is required.

Three fundamental components are distinguished that strictly determine the adequate functioning level of the entire hemodynamic system:

• Cardiac activity. The myocardium acts as the main pump, and any deviations in its contractility instantly affect systemic blood flow.
• Vascular tone. The vascular bed must adequately respond to the body's needs by changing its lumen to redistribute blood flow.
• Blood status. Two aspects are critical here: first, the total and directly circulating blood volume; second, its rheological properties (fluidity, viscosity).

Essence of circulatory failure

Any disruption in at least one of the aforementioned components (cardiac, vascular, or blood-related) inevitably triggers a cascade of pathological reactions. The outcome of such a failure is the development of circulatory failure (CF).

From the perspective of pathopsychology and pathophysiology, circulatory failure is defined as a standard pathological form of the circulatory system. The main characteristic of this condition is that the system completely or partially loses its ability to meet the tissue and internal organ demands for optimal blood supply.

Classification criteria

To make an accurate diagnosis and understand the pathogenesis, circulatory failure is differentiated according to a number of strict criteria. In modern practice, it is customary to distinguish four main classification vectors:

1. By the degree of compensation of the occurred disorders.
2. By the acuteness of development of the pathological process and the nature of its course.
3. By the severity of clinical and functional signs (specific stages are distinguished).
4. By the predominant damage to certain structures included in the circulatory system.

Types of circulatory failure

Depending on the rate of development and the degree of the body's adaptation, the pathology is divided into several forms.

By the degree of compensation:

• Compensated CF. With this form, signs of circulatory disorders do not manifest at rest. They are detected only under exertion, when tissue demand increases and the system cannot meet it.
• Uncompensated CF. A more severe variant, in which signs of circulatory disturbance are clearly detected in the patient even at rest.

By the acuteness of the course:

• Acute form. Characterized by an extremely rapid development. Pathological changes develop within several hours or days.
• Chronic form. Characterized by a gradual development. The pathology forms over several months, and in some cases, years.

Characteristics of the initial stage

Based on the severity of signs, three sequential stages of failure development are traditionally distinguished.

Stage I (initial, or stage I CF) At this stage, pathological changes are only beginning to form, but they already affect the performance indicators of the heart muscle. The first stage is characterized by the following functional deviations:

• Decreased myocardial contraction velocity.
• Decreased relaxation velocity of the heart muscle.
• Decreased ejection fraction—an indicator reflecting the efficiency of heart function.

Briefly: answers to topical questions

Class and exam questions

What else to study on this topic

• Characteristics of stages II and III of circulatory failure
• Predominant lesions of individual structures of the circulatory system
• Impact of blood rheological properties on the development of pathology
• Mechanisms of changes in total and circulating blood volume
• Pathogenesis of decreased ejection fraction in the initial stage of CF

Other topics in "Chapter 22. Typical Forms of Pathology of the Circulatory System"

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.