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A prosthetic myocardium: hemodynamic advantages
Insights
A new prosthetic myocardium effectively restores left ventricular function after surgical excision of damaged tissue. This innovative device improves cardiac output and contractility, offering hope for patients with severe heart conditions.
Area of Science:
- Cardiovascular Surgery
- Biomedical Engineering
- Heart Failure Research
Background:
- Surgical excision of large left ventricular aneurysms or infarcts can lead to impaired cardiac performance.
- Reduced ventricular volume and contractility are primary causes of post-surgical left ventricular failure.
- Existing treatments often struggle to fully restore cardiac output after extensive myocardial damage.
Purpose of the Study:
- To evaluate a prototype prosthetic myocardium designed to mimic natural left ventricular function.
- To assess the device's ability to restore ventricular volume and contractility post-excision.
- To investigate the hemodynamic effects of the prosthetic myocardium in a canine model.
Main Methods:
- A canine model was used, involving surgical infarction and excision of approximately 17% of the left ventricle under cardiopulmonary bypass.
- A prototype prosthetic myocardium was implanted to assist the remaining ventricle.
- Hemodynamic parameters were measured before and after device activation to assess its efficacy.
Main Results:
- The prosthetic myocardium significantly improved hemodynamic parameters in dogs with induced congestive heart failure.
- Key improvements included increased mean aortic pressure (19%), left ventricular systolic pressure (24%), and stroke volume (34%).
- The device also reduced left ventricular end-diastolic pressure (43%) and mean left atrial pressure (22%), while increasing left ventricular stroke work (88%).
Conclusions:
- The prototype prosthetic myocardium demonstrates significant potential for restoring cardiac function after extensive left ventricular damage.
- The device effectively addresses both volume reduction and contractility impairment, crucial factors in post-surgical heart failure.
- This represents a promising advancement towards developing an orthotopic device for myocardial replacement.
Abstract:
When a large left ventricular aneurysm or infarct is excised, a frequent complication is inability of the left ventricle to regain adequate performance. Reduction in ventricular volume and impairment of myocardial contractility, either of which can diminish cardiac output to levels incompatible with life, are probably the main factors that lead to left ventricular failure after such surgery. A prototype prosthetic myocardium, designed to mimic the actions of the left ventricular myocardium, offers a direct means of restoring both ventricular volume and contractility after excision of a large portion of the left ventricle. In dog experiments 17 +/- 1.1% (AV +/- SE) of the left ventricle was infarcted and excised under cardiopulmonary bypass. The prosthetic myocardium was implanted and activated, and changes in hemodynamic parameters produced by the assist device were studied. "On" to "off" changes in 11 dogs in congestive failure averaged over the course of the experiment were as follows: m-AoP was increased 19 +/- 1.7% (Mean +/- SE): LV Syst. Press. was increased 24 +/- 1.7%; SV was increased 34 +/- 3.2%, LVEDP and m-LAP were reduced 43 +/- 2.4% and 22 +/- 1.4% respectively; and LVSW incrdased 88 +/- 8.8%. With these hemodynamic benefits this prototype represents an encouraging step toward the development of a device for orthotopic replacement of damaged myocardium.