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Ann Thorac Surg 2000;70:1124-1126
© 2000 The Society of Thoracic Surgeons
a Department of Cardiac Surgery, Austin and Repatriation Medical Centre, Heidelberg, Victoria, Australia
Address reprint requests to Dr Raman, Department of Cardiac Surgery, Austin and Repatriation Medical Centre, Heidelberg VIC 3084, Australia
e-mail: jraman{at}austin.unimelb.edu.au
Presented at the Sixth Annual Cardiothoracic Techniques and Technologies Meeting 2000, Ft Lauderdale, FL, Jan 2729, 2000.
| Abstract |
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Methods. Five patients with symptomatic heart failure and ischemic cardiomyopathy were enrolled in a Phase I study, and underwent ventricular containment with custom-made polyester mesh along with coronary artery bypass grafting. Four patients had additional ventricular reconstruction of large myocardial scars.
Results. All patients were in NYHA functional class III at the time of their operation with a mean ejection fraction of 27.4% ± 6.6%. There were no deaths. Mean postoperative ejection fraction was 35.1% ± 12.6% (p = 0.16). Left ventricular end-diastolic diameter fell from 63.2 ± 1.6 mm preoperatively to 50.6 ± 5 mm, postoperatively (p = 0.004). There was no evidence of diastolic dysfunction or pericardial constriction on intra- or postoperative echocardiography. At a mean follow-up of 180 days all patients were in NYHA class I with no readmissions for heart failure. Repeat coronary angiography at 6 months revealed patent grafts in all patients.
Conclusions. Ventricular containment with a customized mesh may be performed safely as an adjunct to conventional cardiac operation in patients with symptomatic heart failure. Longer follow-up with an expansion of the study will help delineate the long-term effects of this therapy.
| Introduction |
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Dynamic cardiomyoplasty, a technique that involves wrapping the left latissimus dorsi muscle around the ventricles, was developed in the 1980s with reasonable success in treating heart failure [3]. Copuya and coworkers [4] showed that the latissimus dorsi muscle had a girdling effect on the heart, whereas Patel and colleagues [5] showed the muscle actually worked by preventing ventricular dilatation. Ventricular containment with a custom-made polyester mesh in heart failure evolved from these concepts, with encouraging results in animal models of heart failure [6]. Long-term implant studies in sheep have shown that the deleterious effects of heart failure are avoided without evidence of pericardial constriction. The polyester mesh was well tolerated without invasion of underlying epicardium. A Phase I study was established in human patients with heart failure to ensure safety of the implanted polyester device.
| Material and methods |
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Patients were enrolled in the study based on a combination of entry criteria, namely:
Left ventricular ejection fraction less than 35% on radionuclide ventriculogram (RNVG);
Symptomatic heart failure;
Left ventricular end-diastolic dimensions of more than 30 mm/m2 body surface area; and
Coronary artery disease amenable to CABG.
Patients that required emergent or urgent surgical intervention were excluded. Other exclusions were redo operation, major malignancy, or significant renal impairment with a serum creatinine concentration greater than 160 mmol/L.
As part of their preoperative workup, patients had cardiopulmonary exercise tests, 6-minute walks, detailed transthoracic echocardiography, and RNVG.
Surgical procedure
The implantation of the polyester required some modification of the cardiac surgical procedure. Once the graft conduits for CABG were harvested, the ascending aorta and right atrium were cannulated. Before the patient was connected to cardiopulmonary bypass (CPB), the circumference of the base of the ventricles was measured along with the apex to base length. The patient was then connected to the heart-lung machine. The sites of the distal anastomoses were then identified and marked with hemostatic clips. The aorta was cross-clamped and blood cardioplegia infused to induce cardiac standstill. Any large aneurysmal or dyskinetic left ventricular scar was then excised and the underlying ventricle reconstructed by a geometric endoventricular repair [7]. The polyester CSD was then selected (Fig 1). The CSD was then placed around the ventricles and anchored along the atrioventricular groove posteriorly. The distal anastomoses were then constructed with small windows created in the mesh to allow suturing (Fig 2). The edges of the windows were sutured down to the epicardium to prevent encroachment of the anastomoses or grafts. The cross-clamp was removed and the patient weaned off CPB. At this stage with the filling pressures similar to those before CPB, excess mesh was excised anteriorly from apex to base (Fig 1). The cut edges of the mesh were then approximated with 4-0 Prolene (Ethicon, Somerville, NJ) sutures in such a way that the CSD covered the ventricles in a snug fashion (Fig 2). Implantation and tailoring of the mesh took about 25 minutes. Once the patient was decannulated, the pericardium was closed.
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Statistical methods
Values are expressed as mean ± standard deviation. For continuous variables with a normal distribution, parameters were compared pre- and postoperatively, using the paired t test. A p value of less than 0.05 was considered significant.
| Results |
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There were no episodes of heart failure postoperatively. None of these study patients required further increase or titration of antifailure therapy. All patients were in NYHA class I at the time of review (mean postoperative duration 180 days, range 170 to 200 days).
Echocardiography showed that preoperative left ventricular end-diastolic dimension (LVEDD), which was 63.2 ± 1.6 mm, fell to 50.6 ± 5.03 mm in the first postoperative month (p = 0.004). At 3 months after the operation, the LVEDD had risen slightly to 53 ± 6.9 mm. Though this slight change in the postoperative period was not significant, it was significantly better than the preoperative LVEDD (p = 0.025). Ejection fraction, measured by gated blood pool scan using RNVG, improved from 27.4 ± 6.6 % preoperatively to 35.1 ± 12.6% 6 months postoperatively (p = 0.16), but did not reach statistical significance because of the small number of patients. A slight improvement was also noted in
O2max measured by cardiopulmonary exercise tests performed preoperatively (mean 14.38 ± 8.23 mL/kg per minute) and 3 months postoperatively (mean 15.38 ± 8.23 mL/kg per minute) (p = 0.5). None of the 5 patients had any further hospitalizations for heart failure during the 6 months of follow-up. All patients continued on an angiotensin-converting enzyme inhibitor.
Repeat coronary angiography was performed 6 months postoperatively in all patients. This test showed that all grafts were patent with no suggestion of the CSD impinging on the anastomoses, grafts, or epicardial coronary arteries.
During the 2.5 months over which these patients had their implants, 7 other patients with similar pathophysiology presented for urgent revascularization. These patients also had severe impairment of ventricular function but were excluded because they were unstable or required urgent operation. Although there were no deaths in this group of comparable patients, each of them required further increase in heart failure therapy or readmission for heart failure management, in the 6 months after the operation.
| Comment |
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Our own experience with animals in chronic moderate and advanced heart failure showed that containing the ventricles prevented progression of congestive heart failure and its deleterious effects [6].
Thereafter, we investigated ventricular containment in severe heart failure and tested exercise capability of the sheep in addition to quantifying heart size and function. Sheep in severe heart failure with long-term implants of the mesh also demonstrated significant survival with hemodynamic benefit from containment compared with controls. We found that the fibrous layer surrounding the custom-made polyester mesh resolved with time with no evidence of invasion of the underlying epicardium. This finding provided the impetus for the safety or Phase I study. Because more than half the patients with symptomatic heart failure have ischemic heart disease as the cause [9], we chose to focus on this group of patients.
Although the group of patients was small, the aim of this study was to demonstrate safety of the new device, namely, the custom-made polyester mesh. The next phase of the study will concentrate on efficacy and we hope to move to a randomized protocol in the near future.
| Footnotes |
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| References |
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