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The Journal of Cardiovascular Surgery 2001 February;42(1):1-7


language: English

Effects of “Hot shot” on recovery after hypothermic ischemia in neonatal lamb heart

Nomura F., Forbess J. M., Mayer E. Jr.

From the Department of Cardiovascular Surgery Children’s Hospital, Boston The Department of Surgery Harvard Medical School, Boston, USA


Background. Terminal ­warm ­blood car­di­o­ple­gia, ''Hot ­shot'', is the meth­od for pro­vid­ing an ener­gy replen­ish­ment and/or ear­ly recov­ery of aero­bic metab­olism with­out elec­tro­me­chan­i­cal activ­ity at ­initial reper­fu­sion. The mech­a­nism of ben­e­fi­cial ­effects of ­this “Hot Shot” is mul­ti­fac­to­ri­al. This ­study was ­designed to ­assess the ­effects of ter­mi­nal ­warm ­blood car­di­o­ple­gia by com­par­ing ­with oxy­gen­at­ed ter­mi­nal ­warm crys­tal­loid car­di­o­ple­gia.
Methods. In Group HS-B, n=8 (oxy­gen­at­ed ­blood; 37°C, Ht: 20%, K+ 20 mEq/l, pH 7.237, PO2 219 mmHg) and in Group HS-C, n=8 (blood­less oxy­gen­at­ed (5% CO2+95%O2) crys­tal­loid, 37°C, K+ 20 mEq/l, pH 7.435, PO2 624 mmHg), ter­mi­nal ­warm car­di­o­ple­gia (20 ml/kg for 5 min­utes) was stud­ied in the iso­lat­ed ­blood per­fused neo­na­tal ­lamb ­heart fol­low­ing 2 hr of car­di­o­pleg­ic ische­mia. Another ­eight ­hearts ­served as con­trol with­out any ­kind of ter­mi­nal car­di­o­ple­gia. After 60 min of reper­fu­sion, LV func­tion was meas­ured. Coronary ­blood ­flow (CBF), oxy­gen con­tent, and oxy­gen con­sump­tion (MVO2) ­were meas­ured and the oxy­gen extrac­tion ­ratio was cal­cu­lat­ed in Group HS-B and HS-C dur­ing ter­mi­nal car­di­o­ple­gia and/or reper­fu­sion. Results are giv­en as % recov­ery of pre­is­chem­ic val­ues.
Results. HS-B as ­well as HS-C ­groups ­showed bet­ter func­tion­al recov­ery in max­i­mum developed pres­sure (DP: 78.0±8.3 in HS-B vs 65.2±9.2%; p=0.018), max­i­mum dp/dt (67.3±6.2 in HS-B, 65.3±7.4 in HS-C vs 55.8±5.0%; p=0.003, p=0.02), DP V10 (87.1±8.5 in HS-B vs 67.2±9.9%; p=0.0001), and ­peak dp/dt V10 (76.4±7.6 in HS-B, 69.8±8.1 in HS-C vs 58.6±6.9 %; p=0.0001) ­than the con­trol ­group. Between the HS-B and HS-C ­groups, HS-B ­showed bet­ter func­tion­al recov­ery in ­terms of DP V10 (p=0.01). Oxygen deliv­ery of ter­mi­nal car­di­o­ple­gia was ­almost ­four ­times high­er in HS-B ­group (90.4±17.7 vs 18.7±1.1 mcl/ml), con­tra­ri­ly, HS-C ­group ­showed ­four ­times high­er oxy­gen extrac­tion ­ratio com­pared to HS-B ­group (0.78±0.06 vs 0.18±0.11), ­thus oxy­gen con­sump­tion dur­ing hot ­shot was main­tained at the ­same lev­el in ­both ­groups. CBF in the con­trol ­group was low­er ­than ­that in the oth­er ­groups at 60 min of reper­fu­sion.
Conclusions. Reperfusion ­with ­both ter­mi­nal ­warm car­di­o­ple­gia includ­ing ­blood and oxy­gen­at­ed crys­tal­loid car­di­o­ple­gia result­ed in bet­ter recov­ery of func­tion and high­er lev­els of CBF ­with slight­ly bet­ter func­tion in ter­mi­nal ­warm ­blood car­di­o­ple­gia.

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