Preliminary Observation of Microcirculation Changes During External Counterpulsation for Cardiovascular and Cerebrovascular Diseases: A Comparative Analysis of 180 Cases Before and After Treatment
Authors
Minhua Lu, Qiguang Tang
Guangxi Nationality Hospital
Compiled, Reviewed, and Organized by Dr. Guoji Gong, usecp.com
Abstract
Background: External Counterpulsation (ECP) is a new technology applied in China over the past decade for the treatment of ischemic cardiovascular and cerebrovascular diseases, yielding favorable clinical results. According to the microcirculation theory, these diseases are characterized by microcirculatory disturbances. This study aimed to observe the microcirculatory changes in patients with ischemic cardiovascular and cerebrovascular diseases treated with ECP to explore the intrinsic link between ECP and microcirculation improvement.
Methods: A total of 180 subjects were included: 60 cases of coronary heart disease (CHD), 60 cases of cerebral thrombosis (CT), and 60 healthy controls. Diagnoses for patients followed internal medicine standards. Microcirculation of the nailfold and bulbar conjunctiva was observed using standard protocols. Indices included microvascular loops, microvascular blood flow, and perivascular changes. ECP treatment was administered once daily for one hour, with 12 sessions constituting one course. Patients generally underwent 2–3 courses.
Results: Before ECP, the arterial and venous diameters of the nailfold microvascular loops in both CHD and CT groups were significantly smaller compared to the healthy control group (P<0.01). The incidence of slow blood flow, segmentation, and perivascular hemorrhage in both patient groups was significantly higher than in controls (P<0.01). Similarly, in the bulbar conjunctiva microcirculation, the incidence of microvascular blood flow aggregation, interrupted flow, and perivascular exudation was significantly higher in patient groups (P<0.01). After ECP treatment, all microcirculation indices showed significant improvement, with differences being highly significant compared to pre-ECP measurements (P<0.01).
Conclusion: Patients with ischemic cardiovascular and cerebrovascular diseases exhibit significant microcirculatory disturbances. ECP treatment effectively improves these microcirculatory abnormalities, suggesting that microcirculation enhancement may be a key mechanism of ECP therapy.
Keywords: External Counterpulsation; Microcirculation; Coronary Heart Disease; Cerebral Thrombosis
Subjects and Methods
A total of 180 subjects were observed in this study: 60 cases of Coronary Heart Disease (CHD), 60 cases of Cerebral Thrombosis (CT), and 60 healthy controls.
- Inclusion Criteria: Patients had confirmed diagnoses of ischemic cardiovascular or cerebrovascular disease according to standard internal medicine diagnostic criteria and were treated as inpatients or outpatients. The healthy control group consisted of workers and cadres confirmed to be healthy after physical examinations, excluding cardiovascular and cerebrovascular diseases.
- Demographics: 110 males, 65 females, with a mean age of 55.82 years.
- Microcirculation Observation Methods and Indices: Observation of the nailfold and bulbar conjunctiva microcirculation followed the routine procedure established by the Pathophysiology Research Group of Shanghai First Medical College. Observation indices included: microvascular loops, microvascular blood flow, and perivascular changes. Normal values were based on general domestic standards.
- Instrumentation: The microcirculation microscope and cold light source with photographic device were used, manufactured by the Nanchang Electronic Technology Development Center, equipped with a calibrated eyepiece micrometer.
- External Counterpulsation (ECP) Procedure: According to standard procedure, ECP was administered once daily for one hour. Twelve sessions constituted one treatment course. Each patient generally underwent 2 to 3 courses.
Results
1. Changes in Nailfold Microvascular Loop Diameter
Table I. Changes in Arterial End Diameter of Nailfold Microvascular Loops Before and After ECP (μm)
| Group | N | Xˉ±S | P |
|---|---|---|---|
| Control | 60 | 9.05±2.98 | — |
| CHD Pre-ECP | 60 | 5.73±1.69 | <0.01 |
| CHD Post-ECP | 60 | 8.33±2.26 | <0.01 |
Table II. Changes in Venous End Diameter of Nailfold Microvascular Loops Before and After ECP (μm)
| Group | N | Xˉ±S | P |
|---|---|---|---|
| Control | 60 | 17.15±4.81 | — |
| CHD Pre-ECP | 60 | 14.25±3.99 | <0.01 |
| CHD Post-ECP | 60 | 17.23±3.61 | <0.01 |
Analysis: In the healthy control group, only 15 cases (25.00%) showed slow/segmented nailfold blood flow. In the CHD group, 58 cases showed slow/segmented blood flow before ECP, which recovered to only 3 cases after ECP. The difference between the pre-ECP group and the control group, as well as the difference between pre- and post-ECP, was highly significant (P<0.01). In the CT group, 55 cases (91.66%) showed slow blood flow before ECP, reducing to only 9 cases after ECP. The difference between the CT post-ECP group and the control group, as well as the difference versus the pre-ECP group, was highly significant (P<0.01).
Analysis: Comparison of the arterial and venous end diameters of the nailfold microvascular loops between the CHD group (60 cases) and CT group (60 cases) before ECP versus the healthy control group showed a highly significant difference (P<0.01). The difference between the pre- and post-ECP measurements in both groups was also highly significant (P<0.01).
2. Changes in Nailfold Microcirculation Blood Flow Velocity and State
Table III. Changes in Nailfold Microcirculation Blood Flow Velocity and State Before and After ECP
| Group | N | Slow/Segmented Blood Flow (Cases) | Proportion (%) | P Value |
|---|---|---|---|---|
| Control | 60 | 15 | 25.00 | — |
| CHD Pre-ECP | 60 | 58 | 96.66 | <0.01 |
| CHD Post-ECP | 60 | 3 | 5.00 | <0.01 |
| CT Pre-ECP | 60 | 55 | 91.66 | <0.01 |
| CT Post-ECP | 60 | 9 | 12.00 | <0.01 |
3. Changes in Perivascular Hemorrhage of Nailfold Microvascular Loops
Table IV. Changes in Perivascular Hemorrhage of Nailfold Microvascular Loops Before and After ECP
| Group | N | Perivascular Hemorrhage (Cases) | Proportion (%) | P Value |
|---|---|---|---|---|
| Control | 60 | 5 | 8.33 | — |
| CHD Pre-ECP | 60 | 34 | 56.66 | <0.01 |
| CHD Post-ECP | 60 | 4 | 6.66 | <0.01 |
| CT Pre-ECP | 60 | 41 | 68.33 | <0.01 |
| CT Post-ECP | 60 | 6 | 10.00 | <0.01 |
Analysis: Only 5 cases in the healthy control group showed perivascular hemorrhage. The CHD pre-ECP group had 34 cases, and the CT pre-ECP group had 41 cases. After ECP treatment, both groups showed improvement. The difference between pre- and post-ECP in both groups was highly significant (P<0.01). The difference between the pre-ECP groups and the healthy control group was also highly significant (P<0.01).
4. Dynamic Changes in Bulbar Conjunctiva Microvasculature
Table V. Dynamic Changes in Bulbar Conjunctiva Microvasculature Before and After ECP
| Group | N | Microvascular Blood Flow Aggregation (Cases) | Proportion (%) | P Value |
|---|---|---|---|---|
| Control | 60 | 13 | 21.66 | — |
| CHD Pre-ECP | 60 | 60 | 100.00 | <0.01 |
| CHD Post-ECP | 60 | 21 | 35.00 | <0.01 |
| CT Pre-ECP | 60 | 60 | 100.00 | <0.01 |
| CT Post-ECP | 60 | 29 | 48.33 | <0.01 |
Analysis: Blood flow aggregation was observed in 13 cases (21.66%) in the control group. In the CHD pre-ECP group, 60 cases (100.00%) showed aggregation, which decreased to 21 cases (35.00%) after ECP. The difference between pre- and post-ECP was highly significant (P<0.01). In the CT group, 60 cases (100.00%) showed blood flow aggregation before ECP, which decreased to 29 cases (48.33%) after ECP. The difference between pre- and post-ECP was highly significant (P<0.01). Both patient groups pre-ECP differed highly significantly from the control group (P<0.01).
5. Morphological Changes in Bulbar Conjunctiva Microvasculature
Table VI. Morphological Changes in Bulbar Conjunctiva Microvasculature Before and After ECP
| Group | N | Interrupted Microvascular Flow (Cases) | Proportion (%) | P Value |
|---|---|---|---|---|
| Control | 60 | 0 | 0.00 | — |
| CHD Pre-ECP | 60 | 46 | 76.66 | <0.01 |
| CHD Post-ECP | 60 | 9 | 15.00 | <0.01 |
| CT Pre-ECP | 60 | 44 | 73.33 | <0.01 |
| CT Post-ECP | 60 | 10 | 16.66 | <0.01 |
Analysis: No cases of interrupted microvascular flow were found in the control group. The CHD pre-ECP group had 46 cases (76.66%) and the CT pre-ECP group had 44 cases (73.33%). After ECP treatment, the CHD group had only 9 cases (15.00%) and the CT group had only 10 cases (16.66%). The difference between pre- and post-ECP in both groups was highly significant (P<0.01). The difference between the pre-ECP groups and the healthy control group was also highly significant (P<0.01).
6. Perivascular Changes in Bulbar Conjunctiva Microvasculature
Table VII. Perivascular Changes in Bulbar Conjunctiva Microvasculature Before and After ECP
| Group | N | Perivascular Exudation (Cases) | Proportion (%) | P Value |
|---|---|---|---|---|
| Control | 60 | 3 | 5.00 | — |
| CHD Pre-ECP | 60 | 55 | 91.66 | <0.01 |
| CHD Post-ECP | 60 | 4 | 6.66 | <0.01 |
| CT Pre-ECP | 60 | 58 | 96.66 | <0.01 |
| CT Post-ECP | 60 | 4 | 6.66 | <0.01 |
Analysis: Perivascular exudation was observed in 3 cases (5.00%) in the control group. The CHD pre-ECP group had 55 cases (91.66%) and the CT pre-ECP group had 58 cases (96.66%). After ECP, the incidence decreased to 4 cases in both the CHD and CT groups. The difference between pre- and post-ECP in both groups was highly significant (P<0.01). The difference between the pre-ECP groups and the healthy control group was also highly significant (P<0.01).
Discussion
Microcirculation is the fundamental structural unit of the circulatory system, referring to the circulation between arterioles and venules (approximately 100 μm in diameter), and is the site for material exchange throughout the body. The stability of the internal environment and the normal function of organs are closely related to the state of the microcirculation. Many diseases, particularly cardiovascular and cerebrovascular diseases, involve varying degrees of microcirculatory disturbances. Our data shows that all 120 patients with cardiovascular and cerebrovascular diseases had microcirculatory abnormalities.
1. Relationship between Cardiovascular/Cerebrovascular Disease and Microcirculation
Changes observed in the nailfold included smaller loop diameters, slow/segmented blood flow, and perivascular hemorrhage. Changes in the bulbar conjunctiva included microvascular blood flow aggregation, interrupted flow, and perivascular exudation. These changes were significantly different from the healthy control group (P<0.01). While it is debated whether microcirculatory disturbance is a cause or a consequence of these diseases, some believe it acts as an intermediate link (e.g., increased blood viscosity → reduced coronary microcirculation → local hypoxia/acidosis → endothelial damage → platelet aggregation/thrombus formation). We believe that cardiovascular and cerebrovascular diseases are intrinsically linked to microcirculatory disturbance.
2. Effect of ECP on Microcirculation
After 2 to 3 courses of ECP treatment, the microcirculatory disturbances in many patients showed distinct improvement, both in the nailfold (Tables I–IV) and bulbar conjunctiva (Tables V–VII). This microcirculatory improvement correlated with clinical recovery. The progressive changes in the bulbar conjunctiva and nailfold microvasculature are clinically recognizable signs of arteriosclerosis, and we observed that the degree of microcirculatory change in CHD correlated with the severity of the condition. However, we consider these microcirculatory changes to be the "consequence" rather than the "cause" of the cardiovascular and cerebrovascular diseases.
3. Mechanism of ECP in Improving Microcirculation
ECP is a non-invasive circulatory assist device. Clinical observation and experimental results suggest that organ circulatory blood flow perfusion (Q) is directly proportional to the perfusion pressure (ΔP) and inversely proportional to vascular resistance (R), i.e., Q∝ΔP/R. ECP increases aortic diastolic pressure, thereby increasing coronary perfusion pressure and improving coronary microcirculation. Concurrently, ECP increases cardiac output and carotid artery blood flow, which improves cerebral microcirculation. It is also hypothesized that the increased aortic diastolic pressure stimulates baroreceptors in the aortic arch and carotid sinus, causing a reflexive vasodilation that helps to clear microcirculatory obstructions. This aligns with observations by international scholars confirming the increase in aortic diastolic pressure during ECP. Therefore, the finding in this study that ECP treatment resulted in larger microvascular diameters, faster blood flow, and increased perfusion pressure may represent the primary mechanism by which ECP regulates and improves microcirculation, providing a reliable reference for the broader application of ECP in disease treatment.