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Left ventricular pressure-volume relationships before and after cardiomyoplasty in patients with heart failure
J J Schreuder1, F H van der Veen, E T van der Velde
1Department of Anesthesiology and Cardiology, Cardiovascular Research Institute, University Hospital Maastricht, The Netherlands. JSCHR@SANE.AZM.NL
Insights
Cardiomyoplasty (CMP) significantly reduces left ventricular volume in patients with dilated cardiomyopathy, improving ventricular function. While CMP actively shrinks the ventricle, it does not prevent volume increases with greater venous return.
Area of Science:
- Cardiology
- Cardiac Surgery
- Biomedical Engineering
Background:
- Dilated cardiomyopathy (DCM) is characterized by ventricular enlargement.
- Cardiomyoplasty (CMP) is a surgical intervention for DCM.
- The mechanism of CMP's benefit (volume reduction vs. prevention of dilatation) requires clarification.
Purpose of the Study:
- To determine if cardiomyoplasty (CMP) reduces existing ventricular dilatation or prevents further dilatation in patients with dilated cardiomyopathy.
- To assess the impact of CMP on left ventricular pressure-volume relationships.
Main Methods:
- Utilized combined micromanometer-conductance catheters to measure left ventricular pressure-volume loops.
- Evaluated six patients with DCM before and at 6 and 12 months post-CMP.
- Induced acute changes in preload and afterload using leg-tilting and nitroglycerin administration.
Main Results:
- Left ventricular end-diastolic volume (EDV) decreased significantly post-CMP (P<.01).
- End-diastolic pressure (EDP) and ejection fraction improved post-CMP (P<.01 and P<.05, respectively).
- Nitroglycerin affected ventricular parameters similarly before and after CMP, suggesting active ventricular reduction by CMP.
Conclusions:
- Cardiomyoplasty (CMP) leads to significant reductions in left ventricular volume up to one year post-surgery.
- CMP actively reduces the dilated ventricle but does not fully prevent increased EDV with augmented venous return.
- The latissimus dorsi muscle wrap in CMP enhances ventricular contraction synchronization and promotes faster left ventricular emptying.
Background:
The aim of this study was to elucidate whether beneficial effects of cardiomyoplasty (CMP) in patients with dilated cardiomyopathy are the result of a decrease in existing ventricular dilatation or a prevention of further dilatation.
Methods And Results:
Combined micromanometer-conductance catheters were used to evaluate left ventricular pressure-volume relationships in six patients with dilated cardiomyopathy before and at 6 and 12 months after CMP. Acute changes in preload and afterload were induced by a standardized leg-tilting intervention and a bolus infusion of nitroglycerin. After CMP, end-diastolic volume (EDV) decreased from 138+/-10 to 103+/-18 mL/m2 (P<.01) at 6 months and to 83+/-17 mL/m2 (P<.01) at 12 months. End-diastolic pressure (EDP) decreased from 20.2+/-6.4 to 13.9+/-7.7 mm Hg (P<.01) at 6 months after CMP. Peak ejection rate and ejection fraction increased at 6 months after CMP from 594+/-214 to 799+/-214 mL/s (P<.05) and from 26.6+/-4.7% to 40.1+/-8.3% (P<.05), respectively. Peak dP/dt decreased at 12 months after CMP from -842+/-142 to -712+/-168 mm Hg/s (P<.05). Leg-tilting before CMP increased EDP from 20.2+/-6.4 to 25.6+/-5.2 mm Hg (P<.01), end-systolic pressure (ESP) from 118+/-17 to 122+/-17 mm Hg (P<.05), and tau from 50.8+/-2.8 to 53.8+/-2.3 ms (P<.05). Six months after CMP, leg-tilting also increased EDV from 103+/-18 to 110+/-22 mL/m2 (P<.05) and ESV from 62+/-14 to 66+/-14 mL/m2 (P<.05). Before CMP, nitroglycerin decreased EDP from 20.2+/-6.4 to 10.4+/-3.8 mm Hg (P<.01), ESP from 118+/-17 to 96+/-11 mm Hg (P<.05), ESV from 100+/-11 to 89+/-7 mL/m2 (P<.05), and tau from 50.8+/-2.8 to 44.5+/-3.7 ms (P<.05). Six months after CMP, nitroglycerin decreased EDP, ESP, and tau to similar values.
Conclusions:
Our findings show that up to 1 year after CMP, marked decreases in left ventricular volume are present. Our measurements suggest that CMP actively reduced the dilated ventricle but did not prevent a higher EDV on an increased venous return. The latissimus dorsi muscle wrap contraction results in better synchronization of contraction and more rapid emptying of the left ventricle.