OBJECTIVES: We studied the effects of chronic left ventricular unloading by a ventricular assist device and assessed left ventricular morphologic and histologic changes. BACKGROUND: The implantable left ventricular assist device has been effective as a "bridge" to cardiac transplantation. Although there are reports documenting its circulatory support, little is known about the effects of chronic left ventricular unloading on the heart itself. METHODS: We performed intraoperative transesophageal echocardiography at the insertion and explanation of a HeartMate left ventricular assist device in 19 patients with end-stage heart failure. They were supported by the assist device for 3 to 153 days (mean [+/-SD] 68 +/- 33). Measurements were taken retrospectively to obtain left atrial and ventricular diameters and interventricular septal and posterior wall thicknesses. Histologic examinations were made from the left ventricular myocardial specimens of 15 patients at the times of insertion and explanation for heart transplantation. Insertion and explanation specimens were compared qualitatively (0 to 3 scale) for wavy fibers, contraction band necrosis and fibrosis, with quantitative measurement of minimal myocyte diameter across the nucleus. RESULTS: Left atrial and left ventricular diastolic and systolic diameters decreased immediately after insertion of the left ventricular assist device (from 46 to 35, 63 to 41 and 59 to 36 mm, respectively, all p < 0.001). Left ventricular wall thickness increased from 10 to 14 mm (p < 0.001) for the interventricular septum and from 10 to 13 mm for the posterior wall (p<0.001). No echocardiographic measurements showed significant subsequent changes at the chronic stage. Myocardial histologic findings demonstrated a reduction in myocyte damage (from 1.9 to 0.5, p<0.001, for wavy fiber and from 1.3 to 0.2, p<0.01, for contraction band necrosis) and an increase in fibrosis (from 1.3 to 1.9, p<0.05), but without significant change in myocyte diameter (from 15.6 to 16.8 micrometer, p=0.065). CONCLUSIONS: Left ventricular unloading with the implantable assist device induces an immediate increase in wall thickness, consistent with the reduction in chamber size, thereby decreasing wall stress. Chronic unloading allows myocardial healing and fibrosis without evidence for ongoing myocyte damage or atrophy. Left ventricular assist device insertion may have a role in "resting" the ventricle for selected patients with heart failure.
OBJECTIVES: We studied the effects of chronic left ventricular unloading by a ventricular assist device and assessed left ventricular morphologic and histologic changes. BACKGROUND: The implantable left ventricular assist device has been effective as a "bridge" to cardiac transplantation. Although there are reports documenting its circulatory support, little is known about the effects of chronic left ventricular unloading on the heart itself. METHODS: We performed intraoperative transesophageal echocardiography at the insertion and explanation of a HeartMate left ventricular assist device in 19 patients with end-stage heart failure. They were supported by the assist device for 3 to 153 days (mean [+/-SD] 68 +/- 33). Measurements were taken retrospectively to obtain left atrial and ventricular diameters and interventricular septal and posterior wall thicknesses. Histologic examinations were made from the left ventricular myocardial specimens of 15 patients at the times of insertion and explanation for heart transplantation. Insertion and explanation specimens were compared qualitatively (0 to 3 scale) for wavy fibers, contraction band necrosis and fibrosis, with quantitative measurement of minimal myocyte diameter across the nucleus. RESULTS: Left atrial and left ventricular diastolic and systolic diameters decreased immediately after insertion of the left ventricular assist device (from 46 to 35, 63 to 41 and 59 to 36 mm, respectively, all p < 0.001). Left ventricular wall thickness increased from 10 to 14 mm (p < 0.001) for the interventricular septum and from 10 to 13 mm for the posterior wall (p<0.001). No echocardiographic measurements showed significant subsequent changes at the chronic stage. Myocardial histologic findings demonstrated a reduction in myocyte damage (from 1.9 to 0.5, p<0.001, for wavy fiber and from 1.3 to 0.2, p<0.01, for contraction band necrosis) and an increase in fibrosis (from 1.3 to 1.9, p<0.05), but without significant change in myocyte diameter (from 15.6 to 16.8 micrometer, p=0.065). CONCLUSIONS: Left ventricular unloading with the implantable assist device induces an immediate increase in wall thickness, consistent with the reduction in chamber size, thereby decreasing wall stress. Chronic unloading allows myocardial healing and fibrosis without evidence for ongoing myocyte damage or atrophy. Left ventricular assist device insertion may have a role in "resting" the ventricle for selected patients with heart failure.
Authors: John V Terrovitis; Christos E Charitos; Elias J Tsolakis; Paraskevi Dolou; Charalampos N Pierrakos; Kostas X Siafakas; John N Nanas Journal: World J Surg Date: 2003-11-05 Impact factor: 3.352
Authors: Konstantinos G Malliaras; John V Terrovitis; Stavros G Drakos; John N Nanas Journal: J Cardiovasc Transl Res Date: 2008-09-30 Impact factor: 4.132
Authors: Stavros G Drakos; Abdallah G Kfoury; Craig H Selzman; Divya Ratan Verma; John N Nanas; Dean Y Li; Josef Stehlik Journal: Curr Opin Cardiol Date: 2011-05 Impact factor: 2.161
Authors: J Müller; G Wallukat; Y G Weng; M Dandel; S Spiegelsberger; S Semrau; K Brandes; H Bieda; M Hummel; M Loebe; R Meyer; R Hetzer Journal: Herz Date: 1997-10 Impact factor: 1.443
Authors: Brian D Lowes; Ronald Zolty; Simon F Shakar; Andreas Brieke; Norman Gray; Michael Reed; Mihail Calalb; Wayne Minobe; JoAnn Lindenfeld; Eugene E Wolfel; Mark Geraci; Michael R Bristow; Joseph Cleveland Journal: J Heart Lung Transplant Date: 2007-11 Impact factor: 10.247