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Functional assessment of skeletal muscle ventricles after pumping for up to four years in circulation  Gregory A Thomas, MD, Robert L Hammond, PhD, Kevin.

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Presentation on theme: "Functional assessment of skeletal muscle ventricles after pumping for up to four years in circulation  Gregory A Thomas, MD, Robert L Hammond, PhD, Kevin."— Presentation transcript:

1 Functional assessment of skeletal muscle ventricles after pumping for up to four years in circulation  Gregory A Thomas, MD, Robert L Hammond, PhD, Kevin Greer, MD, Huiren Lu, MD, Jonathan C Jarvis, PhD, Adam P Shortland, PhD, D.Mark Pullan, Stanley Salmons, PhD, Larry W Stephenson, MD  The Annals of Thoracic Surgery  Volume 70, Issue 4, Pages (October 2000) DOI: /S (00)01732-X

2 Fig 1 Schematic diagram of the SMV in circulation. Connection to the descending thoracic aorta is made via a conical base cap with two conduits sewn to the base of the SMV. The aorta is ligated between the two conduits. The cardiomyostimulator senses the cardiac R-wave and then stimulates the muscle via the thoracodorsal nerve after a delay that places contraction within diastole. The Annals of Thoracic Surgery  , DOI: ( /S (00)01732-X)

3 Fig 2 Pressure and electrocardiographic tracings recorded from the longest surviving animal at the time of connection (A), and after 1 year (B), 2 years (C), and 4 years (D) in the circulation. Stimulation burst frequency is 33 Hz at a 1:2 assist ratio. (Fem P = blood pressure measured at the femoral artery; Carotid P = pressure measured at the carotid artery.) The Annals of Thoracic Surgery  , DOI: ( /S (00)01732-X)

4 Fig 3 Augmentation of mean diastolic pressure at 33-Hz burst frequency, expressed as a percentage of the unassisted mean diastolic pressure, over the period of study for the dog surviving for 4 years (open circles) and for the other dogs in the experimental group (closed circles). At connection, n = 10; at 6 months, n = 6; at 1 year, n = 5; at 2 years, n = 3; at 3 years, n = 2. The Annals of Thoracic Surgery  , DOI: ( /S (00)01732-X)

5 Fig 4 Changes in mean diastolic pressure (A) and presystolic pressure (B) as measured in the thoracic aorta or femoral artery. (Filled columns = Control values, from a prolonged period with the stimulator “off”; open columns = stimulation of the SMV at 33-Hz burst frequency; cross-hatched columns = stimulation of the SMV at either 50- or 85-Hz burst frequency.) Data are averaged for all dogs alive at each time point (at connection, n = 10; at 6 months, n = 6; at 1 year, n = 5; at 2 years, n = 3; at 3 years, n = 2; and at 4 years, n = 1.) The Annals of Thoracic Surgery  , DOI: ( /S (00)01732-X)

6 Fig 5 (a) Pressure developed by the SMV of the dog surviving for 4 years, measured under controlled conditions after disconnecting it from the aorta. The traces represent pressures (in mm Hg) developed during ejection of saline solution under isovolumetric conditions (flow = 0), and for constant flow rates up to 60 mL/s. (b) Similar graph for a SMV constructed and tested acutely in a sheep. The hydraulic pumping performance of the SMVs is similar, despite the species difference and the 4-year difference in functional history. The Annals of Thoracic Surgery  , DOI: ( /S (00)01732-X)

7 Fig 6 Photomicrographs of sections from the wall of the SMV of the dog surviving for 4 years, stained histologically by the regressive hematoxylin and eosin technique (A, B) and immunohistochemically with antibodies to myosin heavy chain isoforms (C–E). (A) Full-thickness section of the wall at middle east (see Material and Methods for sampling scheme); the luminal surface is seen on the right, and is partly detached. The pericardial layer can no longer be distinguished as a discrete feature of this lining but has become continuous with superficial connective tissue of the SMV wall. Note the excellent morphological preservation and normal thickness of perimysial septa (bar = 1 mm). (B) Nearly full-thickness section of the wall at proximal north; again, the luminal surface is on the right. Note thicker lining and relatively undamaged muscle fascicles interspersed with areas of fibrofatty replacement. Same magnification as A. (C–E). Serial sections from middle west, stained with myosin heavy chain antibodies specific to the fast (C), slow (D), and neonatal (E) isoforms and photographed at the same magnification. All fibers stain negatively for fast myosin heavy chains and positively for slow myosin heavy chains, evidence of a history of continuous stimulation. Lack of staining for the neonatal isoform (C) confirms the absence of regenerative phenomena (bar = 400 μm). The Annals of Thoracic Surgery  , DOI: ( /S (00)01732-X)


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