Hypoxic Hypoperfusion Fails to Induce Myocardial Hibernation in Anesthetized Swine

Cardiovascular magnetic resonance assessment of ventricular function and myocardial scarring before and early after repair of anomalous left coronary artery from the pulmonary artery

BACKGROUND

In patients with anomalous left coronary artery from the pulmonary artery (ALCAPA) left ventricular (LV) dilatation and dysfunction evolves due to diminished myocardial perfusion caused by coronary steal phenomenon. Using late gadolinium enhanced cardiovascular magnetic resonance (LGE-CMR) imaging, myocardial scarring has been shown in ALCAPA patients late after repair, however the incidence of scarring before surgery and its impact on postoperative course after surgical repair remained unknown.

METHODS

8 ALCAPA-patients (mean age 10.0 ± 5.8 months) underwent CMR before and early after (mean 4.9 ± 2.5 months) coronary reimplantation procedures. CMR included functional analysis and LGE for detection of myocardial scars.

RESULTS

LV dilatation (mean LVEDVI 171 ± 94 ml/m2) and dysfunction (mean LV-EF 22 ± 10 %) was present in all patients and improved significantly after surgery (mean LVEDV 68 ± 42 ml/m2, p=0.02; mean LV-EF 58 ± 19 %, p<0.001). Preoperative CMR revealed myocardial scarring in 2 of the 8 patients and did not predict postoperative course. At follow-up CMR, one LGE-positive patient showed delayed recovery of LV function while myocardial scarring was still present in both patients. In two patients new-onset transmural scarring was found, although functional recovery after operation was sufficient. One of them showed a stenosis of the left coronary artery and required resurgery.

CONCLUSIONS

Despite diminished myocardial perfusion and severely compromised LV function, myocardial scarring was preoperatively only infrequently present. Improvement of myocardial function was independent of new-onset scarring while the impact of preoperative scarring still needs to be defined.

Long-term myocardial scarring after operation for anomalous left coronary artery from the pulmonary artery

BACKGROUND

Anomalous left coronary artery from the pulmonary artery (ALCAPA) is a very rare disease. Accordingly, the incidence and distribution of myocardial scarring in long-term follow-up of patients after successful surgery of ALCAPA is unknown. Therefore, the aim of this study was to describe the distribution of left ventricular (LV) myocardial scarring by late gadolinium enhancement magnetic resonance in these patients.

METHODS

Fourteen consecutive patients over 12 years of age with ALCAPA without any further cardiac abnormalities, and after corrective surgery at our center, participated prospectively in this study. All patients underwent cardiac magnetic resonance including LV function analysis and late gadolinium enhancement magnetic resonance. Of these 14 patients, 12 patients also underwent cardiopulmonary exercise testing.

RESULTS

Four patients had no evidence of myocardial scarring. The median extent of the myocardial scar of all patients by late gadolinium enhancement magnetic resonance, expressed as a percentage of the total LV myocardial volume, was only 2% (range, 0% to 11%). Median LV ejection fraction was 0.55 (range, 0.31 to 0.73). Median LV end-diastolic volume indexed to body surface area was 84 mL/m(2) (39 to 120 mL/m(2)). Median peak oxygen uptake during cardiopulmonary exercise was 24 mL · kg(-1) · minute(-1) (range, 19 to 51 mL/kg/minute).

CONCLUSIONS

We conclude that despite often severely compromised LV function and evidence of scarring before corrective surgery of patients with ALCAPA, in long-term follow-up scar tissue is relatively scarce.

The representative porcine model for human cardiovascular disease

To improve human health, scientific discoveries must be translated into practical applications. Inherent in the development of these technologies is the role of preclinical testing using animal models. Although significant insight into the molecular and cellular basis has come from small animal models, significant differences exist with regard to cardiovascular characteristics between these models and humans. Therefore, large animal models are essential to develop the discoveries from murine models into clinical therapies and interventions. This paper will provide an overview of the more frequently used large animal models, especially porcine models for preclinical studies.

A novel minimal-invasive model of chronic myocardial infarction in swine

BACKGROUND

Most animal studies on myocardial infarction (MI) have used open-chest models with direct surgical coronary artery ligation, which imply local as well as generalized side effects of major surgery. Some closed-chest models of MI have been established, mainly using catheterization techniques with coronary artery embolization, balloon occlusion, and intracoronary injection of thrombogenic agents. The aim of this study was to develop a closed-chest technique of chronic coronary artery occlusion at a selected location with subsequent thrombus formation without use of balloon inflation or thrombotic chemical agents.

METHODS AND RESULTS

A coronary angiography via the carotid artery was performed using a 7 F guiding catheter in 21 pigs. After insertion of a percutaneous transluminal coronary angioplasty (PTCA) guide wire into the distal coronary artery, a vessel-size adapted flexible foreign body comprising an open-cell sponge was advanced into the coronary artery via the guide wire by a non-inflated PTCA balloon. Five min after removal of the guide wire and the balloon catheter, total coronary artery occlusion was documented by angiography. Retrograde thrombosis of the coronary artery occurred in three animals. After one week, total vessel occlusion at the previously selected location was visualized by coronary angiography in animals that had survived. Macroscopic analysis demonstrated the foreign body with subsequent thrombus formation in the coronary artery and distal MI. Post-mortem histological analysis revealed myocardial necrosis and granulocyte infiltration at the margin of the infarction, without damage to remote myocardium.

CONCLUSIONS

This new easy-to-perform closed-chest technique provides reproducible chronic coronary artery occlusion at a selected location with subsequent MI. It avoids major surgery and thoracotomy and does not require balloon inflation or intracoronary injection of thrombotic or chemical agents.