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Early postoperative changes in regional systolic and diastolic left ventricular function after transmyocardial laser revascularization

A comparison of holmium:YAG and CO₂ lasers

^a Duke University Medical Center, Durham, North Carolina, USA

View larger version (67K): [in a new window]   Figure 1 Experimental preparation demonstrating pairs of intramyocardial dimension transducers in region undergoing TMR (anterolateral left ventricular free wall) and control region (posterolateral left ventricular free wall). Fifteen transmural TMR channels were placed at 1 cm intervals in lased region. Care was taken to avoid all epicardial and intramyocardial vessels. Also shown is the left atrial catheter used for injection of radioactive microspheres. Superior and inferior vena caval occluders and left ventricular pressure transducer not shown. TMR = transmyocardial laser revascularization.

View larger version (32K): [in a new window]   Figure 2 Typical digital recordings for lased and nonlased regions of segment length and left ventricular pressure at baseline, 1 h and 6 h after TMR with a holmium:YAG laser in a representative animal. TMR = transmyocardial laser revascularization.

View larger version (15K): [in a new window]   Figure 3 Regional stroke work versus end-diastolic segment length curves for the lased regions in representative animals undergoing TMR with: (A) holmium:YAG and (B) CO2 lasers. Note the rightward shift in the x-intercept representing diastolic creep in the holmium:YAG lased regions. This rightward shift is characteristic of ischemic myocardial dysfunction (22). Preload recruitable work area was calculated from the area under these curves for each individual animal. TMR = transmyocardial laser revascularization. Closed diamond = baseline; open square = 1 h post-TMR; solid triangle = 6 h post-TMR.

View larger version (13K): [in a new window]   Figure 4 Preload recruitable work area for lased and nonlased (control) regions after TMR with: (A) holmium:YAG and (B) CO2 lasers. Preload recruitable work area values are expressed as a percent of baseline values in the lased and nonlased regions (normalized), with baseline values assigned a value of 100%. Note the significant decrease in PRWA for the lased regions at both 1 (59.8 ± 13% baseline) and 6 h (64.2 ± 9.4% baseline) after holmium:YAG TMR (absolute PRWA values: baseline 1,882 ± 283 erg-mm, 1 h 1,112 ± 297 erg-mm, 6 h 1,182 ± 214 erg-mm). No significant change in PRWA for the lased regions was seen after CO2 laser TMR (1 h: 86.9 ± 17.5% baseline; 6 h: 97.2 ± 20.8% baseline) (absolute PRWA values: baseline 1,001 ± 238 erg-mm, 1 h 837 ± 275 erg-mm, 6 h 789 ± 98 erg-mm). Likewise, there was no change in PRWA for the nonlased regions after TMR with either holmium:YAG (1 h: 97.0 ± 27.6% baseline; 6 h: 106.1 ± 25.7% baseline) (absolute PRWA values: baseline 1,175 ± 246 erg-mm, 1 h 1,029 ± 213 erg-mm, 6 h 1,153 ± 234 erg-mm) or CO2 (1 h: 103.0 ± 26.4% baseline; 6 h: 128.6 ± 53.2% baseline) (absolute PRWA values: baseline 1,437 ± 609 erg-mm, 1 h 786 ± 247 erg-mm, 6 h 1,135 ± 117 erg-mm) lasers. PRWA = preload recruitable work area; TMR = transmyocardial laser revascularization; holmium:YAG = holmium:yttrium-aluminum-garnet. A: *p = 0.02 vs. baseline; **p = 0.02 vs. baseline. Solid diamond = lased; open square = control.

View larger version (17K): [in a new window]   Figure 5 Representative regional steady-state pressure-strain relations during diastole for the lased region in a single animal at baseline, 1 h and 6 h post-TMR. Note the progressive leftward shift in the pressure-strain relations, consistent with a decrease in regional compliance after TMR. TMR = transmyocardial laser revascularization.

View larger version (13K): [in a new window]   Figure 6 Regional diastolic stiffness () for lased and nonlased regions after TMR with (A) holmium:YAG and (B) CO2 lasers. Values of are expressed as a percent of baseline values in the lased and nonlased regions (normalized), with baseline values assigned a value of 100%. Higher values indicate increasing myocardial stiffness. Note the significant increase in , indicating impaired diastolic relaxation in the lased regions by 6 h post-TMR with both holmium:YAG (1 h: 183.3 ± 56.3% baseline; 6 h: 217.4 ± 44.2% baseline) (absolute values: baseline 67.1 ± 18.5, 1 h 84.4 ± 10.8, 6 h 117.5 ± 9.9) and CO2 (1 h: 112.4 ± 24.7% baseline; 6 h: 206.0 ± 36.7% baseline) (absolute values: baseline 65.3 ± 17.3, 1 h 60.3 ± 10.5, 6 h 120.1 ± 22.8) lasers. There was no change in for the nonlased regions after either holmium:YAG (1 h: 76.2 ± 19.1% baseline; 6 h: 99.5 ± 15.2% baseline) (absolute values: baseline 71.1 ± 5.4, 1 h 53.9 ± 15.6, 6 h 70.8 ± 13.3) or CO2 (1 h: 93.6 ± 19.7% baseline; 6 h: 112.8 ± 32.9% baseline) (absolute values: baseline 119.0 ± 21.6, 1 h 104.2 ± 20.9, 6 h 118.4 ± 22.0) TMR. Closed diamond = lased; open square = control. A: *p = 0.05 vs. baseline; B: *p = 0.03 vs. baseline.