Duke Cameron MD

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On Building a Heart Lessons from Man and Nature
Duke Cameron MD
Cardiac Surgeon-in-Charge Professor of
Surgery Johns Hopkins
 
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Disclosure

• I am not an expert on this subject

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Solomon Victor(1938-2006)

• Cardiac surgeon, humanitarian, evolutionary
  biologist
• Practiced in public sector in Madras and Chennai
• Longstanding interest in evolution of hearts and
  established a museum of comparative cardiac
  anatomy
• Theories every heart beat is under neural
  control, contractile properties of systemic and
  pulmonary veins, and anticipatory evolution.

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• Earth is 4.6 Bn years old
• Life started 4 Bn years ago
• Earliest form of life were anaerobes, fed by
  hydrogen, sulfur and CO2
• Photosynthetic cyanobacteria appear 2.8 BYA and
  yield oxygen
• Enzymes for oxygen metabolism derived from sulfur
  based enzymes, but with more efficiency

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Ingestion of Prokaryotes Leads to Eukaryotes
Multiple mitochondria led to increased energy
generating capacity
Annals of the New York Academy of SciencesVolume
1047, Issue 1, pages 13-29, 9 JAN 2006
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Single cell Eukaryotes split into more than 60
lines
Had cytoskeleton, flagellum, actomyosin, and
directed movement
Annals of the New York Academy of SciencesVolume
1047, Issue 1
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Opisthokonts, Ancestors of Multicellular Life
Poriphera (sponges)
Annals of the New York Academy of SciencesVolume
1047, Issue 1, pages 13-29, 9 JAN
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Development of the Coelem
Coelem served three functions digestion, gas
exchange, and reproduction
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The Coelem

• Eventually differentiated into separate tubes
  (vascular, intestinal, and respiratory)
• Vascular became a closed system
• Digestive and respiratory remained open
• Respiratory became one ended
• Intestinal remained

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Next step development of a neural cord..
and then vertebrae
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Evolution of the Heart
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Why did we evolve 4 chamber hearts and separate
the circulations?

• Maintenance of endothermy and more movement
  increased the need for more efficient oxygen
  delivery
• Larger and more erect species required higher
  systemic blood pressure, yet the pulmonary
  circulation needed lower pressure

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Even though cardiac evolution has marched toward
greater differentiation and specialization, there
still exists tremendous variability in natures
solution for nutrient distribution and gas
exchange
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Octopus Hearts
Copper-based oxygen binding mostly free plasma
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Frog and Lizard Hearts
Double arches and variable septations
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Hibernation

• Body temp even sub-zero (-2 C)
• HR 4 bpm
• Intermittent arousal
• Looses 40 BW
• No food or water for months

Ground squirrel
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Evolution of the Heart and the Core Cardiac
Transcription Factors
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Summary

• Evolution has produced higher performing, more
  differentiated hearts
• Unique solutions for unusual environments are
  still in place
• Natures pleomorphism should inspire us to
  explore novel means to meet the circulatory
  challenge