Systolic and Diastolic Function After Patch Reconstruction of Left Ventricular Aneurysms

Transcription

1 Systolic and Diastolic Function After Patch Reconstruction of Left Ventricular Aneurysms Tetsuji Kawata, MD, Soichiro Kitamura, MD, Kanji Kawachi, MD, Ryuichi Morita, MD, Yoshitsugu Yoshida, MD, and Junichi Hasegawa, MD Department of Surgery III, Nara Medical College, Nara, Japan Left ventricular function after patch reconstruction for postinfarction left ventricular aneurysms is largely unknown. In this study, 16 patients with an anteroseptallateral left ventricular aneurysm were treated by reconstruction of the left ventricle using a Dacron patch. Coronary artery bypass grafting was performed concomitantly in 9 patients. The size of the patch used was 57% % of the resected myocardial scar area, including the sewing cuff area to be sutured. In these patients, the ejection fraction increased significantly from to (p = 0.007) at rest and from to (p = 0.008) during exercise. The left ventricular end-diastolic pressure and left ventricular end- diastolic volume index were reduced significantly from to mm Hg (p = 0.032), and from to ml/m 2 (p = 0.016). The peak filling rate was improved significantly from to /s (p = 0.048) postoperatively. The ratio of the peak flow velocity during the atrial kick phase to the peak flow velocity in the rapid filling phase, at the level of the mitral valve, improved (p = 0.016) after operation and remained improved up to 16 to 24 months after operation. Patch reconstruction of the left ventricle resulted in the recovery of systolic and diastolic function soon after operation, which has persisted into the late postoperative period. (Ann Thorac Surg 1995;59:403-7) I n the past, resection with primary ventricular closure has been the standard surgical procedure for postinfarction left ventricular aneurysms. Recently, Jatene [1], Dor [2], Cooly [3], and their co-workers have begun to reconstruct surgical ventricular wall defects using a Dacron patch. With these techniques, the left ventricular geometry may be restored to a more physiologic state than with direct closure. In addition, septal aneurysms can be eliminated with ease using the patch reconstruction technique. However, few detailed reports [4, 5] on cardiac function after patch reconstruction have been published to date. We evaluated systolic and diastolic function in 16 patients after patch reconstruction for left ventricular aneurysms. The results form the basis of this report. Material and Methods Preoperative Patients" Status Sixteen patients underwent patch reconstruction of the left ventricular wall after left ventricular aneurysmectomy, including 15 men and I woman, with a mean age of 59 _+ 8.8 years (Table 1). Preoperative cardiac status, according to the New York Heart Association classification, was class III in 15 patients and class IV in 1. No patient had been in cardiogenic shock or had experienced intractable ventricular arrhythmias before operation. All patients were in normal sinus rhythm before and after operation. The site of the myocardial infarction was Accepted for publication Sep 27, Address reprint requests to Dr Kawata, Department of Surgery III, Nara Medical College, 840 Shijyo-cho, Kashihara, Nara, Japan by The Society of Thoracic Surgeons identified by electrocardiography in the anteroseptal to lateral walls in all patients. None of the patients demonstrated significant mitral regurgitation during left ventriculography. In all patients, the left anterior descending artery was the artery responsible for the formation of the aneurysm. Stenosis or obstruction of other coronary arteries was noted in 9 patients. Operative Procedures A woven Dacron patch, preclotted with fibrin glue, was used for reconstruction. The resected area of the aneurysmal free wall averaged 40 ± 27 cm 2. The Dacron patch was sutured from the infarcted (scarred) septum to the left ventricular free wall, excluding the septum and aneurysm free wall. The patch size, including the sewing rim, was determined during operation to become less than 50% of the surface area of the resected scar based upon the model analysis described below. However, the actual mean area of the patch, including the area for a sewing cuff, was 57% + 19% of the resected area. The resected scarred myocardium did not include the septal scar; only this was excluded. All operative procedures were performed under hypothermic (25 to 28 C) ventricular fibrillation. In the 9 patients with coronary artery stenosis, coronary artery bypass grafting (CABG) was also carried out after patch reconstruction using a saphenous vein graft. The left anterior descending artery, the artery responsible for the left ventricular aneurysm in all patients, was not bypassed. Cardiac Catheterization Studies In all patients, cardiac catheterization and coronary and left ventricular angiography were performed before and /$ (94)

2 404 KAWATA ET AL Ann Thorac Surg CARDIAC PERFORMANCE AFTER PATCH RECONSTRUCTION 1995;59:403-7 Table 1. Preoperative Patient Profile Patient Characteristic Value Number of patients 16 Sex (M:F) 15:1 Age (y) Body surface area (m 2) Preop NYHA class 3.1 _+ 0.2 Mitral regurgitation 0 Coronary artery disease (no. of diseased vessels) Cardiac index (L. min 1. m-2) 3.03 ± 0.67 Mean PA pressure (mm Hg) LVEDP (mm Hg) LVEDVI (ml/m 2) Global EF CSEF 0.46 _ LVA size (% length) 48 ± 17.8 Resected area (cm 2) 40 ± 27 CABG (no. of patients) 9 (56%) Bypass graft (no.) 1.6 ± 0.6 CABG = aortocoronary bypass grafting; CSEF = contractile sectional ejection fraction; EF = ejection fraction; LVA size = length of left ventricular aneurysm contour divided by whole length of end-diastolic silhouette; LVEDP = left ventricular end-diastolic pressure; LVEDVI left ventricular end-diastolic volume index; NYHA - New York Heart Association; PA = pulmonary artery. 1 to 2 months after operation to measure hemodynamic parameters. The left ventricular end-diastolic pressure and mean pulmonary artery pressure were measured. Cardiac output also was measured by the thermodilution method. The left ventricular end-diastolic volume index (LVEDVI) was calculated by dividing the angiographic stroke volume by the ejection fraction obtained from radioisotopic angiography [6] as described below. Using preoperative left ventriculograms in the right anterior oblique position, the contractile sectional ejection fraction was calculated by Watson and associates' method [7] and the ratio of the circumferential length of the aneurysm to that of the left ventricle was determined. The preoperative contractile sectional ejection fraction was and the ratio of the circumferential length of the aneurysm to that of the left ventricle was 48% % in these patients. Radioisotopic-Angiographic Evaluation An equilibrium cardiac pool image using labeled erythrocytes with 740MBq 99mTc was obtained in the 45- degree left anterior oblique position. The ejection fraction was obtained from the cumulative radioactivity counts. The count curve was subjected to a linear differential to obtain the one-third filling fraction and the peak filling rate [8]. Radioisotopic angiography was performed I to 2 months before and after operation. An incremental ergometer exercise test was employed in 15 patients with the patient in the supine position with submaximal loads. Doppler Ultrasonography Measurements Cardiac ultrasonography was performed 1 month before and on several occasions after operation, ranging from postoperative day 3 to 16 months and up to 24 months (mean, months) after the operation. The ratio of the peak flow velocity during the atrial kick phase to the peak flow velocity in the rapid filling phase at the level of the mitral valve (A/R ratio) [9] was calculated. The sampling point was identified at the center of the mitral orifice using an apical four-chamber view. The A/R ratio was calculated by averaging the values obtained over five cardiac cycles. Statistical Analysis The data are expressed as the mean -- standard deviation. Data were statistically analyzed using paired or nonpaired Student's t test for heart rate and ejection fraction, paired or nonpaired Wilcoxon test for other variables, and analysis of variance. Standard linear regressions were calculated using the least squares method. Results There were no deaths in either the early or late postoperative period up to 7 years after operation. Fourteen patients improved to New York Heart Association class I, and 2 were in class II postoperatively. All 14 grafts in the 9 patients who underwent simultaneous CABG were patent at the time of this study. Hemodynamic Variables There were no significant differences between preoperative and postoperative resting or exercise heart rates (Table 2). The ejection fractions at rest and during exercise increased significantly from 0.28 ± 0.12 to 0.39 ± 0.12 (p = 0.007) and to 0.41 _ (p = 0.008) after operation. The mean pulmonary artery pressure decreased from to mm Hg after operation. However, this difference was not statistically significant. The LVEDVI also decreased significantly from 178 ± 116 to 92 _+ 21 ml/m 2 (p = 0.016) after operation, as did the Table 2. Hemodynamic Changes Before and After Operation Measurement Preop Postop p Value Heart rate at rest (beats 75 _ _ rain) Ejection fraction at rest 0.28 ± Heart rate during exercise 112 ± _ (beats/min) Ejection fraction during 0.32 " ± exercise LVEDP (ram Hg) 14 " Mean PA pressure " (mm Hg) LVEDVI (ml/m 2) ± /3FF (%) 11.3 ± _~ PFR (s ~) 1.2 _ _ /3FF IZ~ filling fraction; LVEDP left ventricular end-diastolic pressure; LVEDVI - left ventricular end-diastolic volume index; Mean PA pressure mean pulmonad, artery, pressure; PFR = peak filling rate.

3 Ann Thorac Surg KAWATA ET AL ;59:403-7 CARDIAC PERFORMANCE AFTER PATCH RECONSTRUCTION Table 3. Sequential Changes in A/R Ratio and Heart Rate Measurement Pre-op 3 days N 16 AIR ratio ~+ 0,50 b HR (beats/min) 75 _+ 10 AIR ratio With concomitant CABG (n = 9) 1.79 _ d Without concomitant CABG (n = 7) 1.87 _ ~'f Postop 7 days 14 days 21 days 3 mo mo a ± _ ± ± _ _ 9 78 _ _ ± _ ± _ f 1.14 ± 0.30 f a Mean, mo. b p = 0.016, preoperative compared with each postoperative time measurement. p = 0.019, 3 days postoperative compared with preoperative and each postoperative time measurement, d p = 0.017, preoperative compared with either postoperative time measurement. e p = 0.014, preoperative compared with either postoperative time measurement, f Not significantly different from corresponding time with CABG. AIR ratio = ratio of the peak flow velocity during the atrial kick phase to the peak flow velocity in the rapid filling phase at the level of the mitra] valve; CABG = aorto-coronary bypass grafting; HR = heart rate; rain = minute. left ventricular end-diastolic pressure, from to mm Hg (p = 0.032). The one-third filling fraction remained higher after operation. The peak filling rate increased significantly from 1.2 Z 0.47 to 1.8 +_ 0.6Is (p = 0.048) after operation. Change in A/R Ratio The ratio was abnormally high before operation, but as early as postoperative day 3, it decreased significantly from 1.82 ± 0.50 to (p = 0.016) (Table 3). The maximum follow-up periods extended to 16 months in 7, 18 months in 4, and 24 months in 5 patients. It then ranged from 0.91 to 1.12 for up to 16 to 24 months (mean, months) through the remainder of the study period. The heart rate was elevated slightly on the third postoperative day, but it did not differ from the preoperative value at any other time in the postoperative period. To examine the effect of CABG on the A/R ratio, we divided 16 patients into 9 with concomitant CABG and 7 without it. In 9 patients with CABG, the AIR ratio before operation was , and that at 16 to 24 month postoperative period was In 7 patients without CABG, the ratio was preoperatively and ~ 0.30 postoperatively. There were no statistically significant differences at either period between the two subgroups. Relationship Between AIR Ratio and Left Ventricular End-diastolic Volume Index The ratio of postoperative AIR ratio to preoperative A/R ratio reveals a positive correlation (r = ; p = 0.014) in relation to the ratio of the postoperative to preoperative LVEDVI (Fig 1). The postoperative reduction in the A/R ratio was greater in patients with a large left ventricular aneurysrn. Comment After direct closure (the conventional surgical procedure) of the left ventricular wall after aneurysmectomy, the LVEDVI decreases significantly, resulting in nearnormalization of preload reserve and reduction of tensile wall force (afterload) [10-12]. This generally leads to improvement in various hemodynamic variables such as ejection fraction, left ventricular end-diastolic pressure, LVEDVI [10], and the ratio of coronary sinus flow to left ventricular mass both at rest and during exercise [13]. Symptoms also frequently are improved by this operation. However, some investigators [14] have reported that alterations of left ventricular geometry occur in the early stages after direct closure, potentially leading to postoperative low cardiac output syndrome. Furthermore, postoperative persistence of small aneurysms, particularly in the ventricular septal area, was often seen in patients with a direct closure. To overcome these problems inherent to the conventional method, patch reconstruction of ventricular aneurysms has recently been advocated [1-3]. However, there are few reports [4, 5] on cardiac performance after patch reconstruction. Our study examines cardiac performance as well as diastolic function after this operation. LVEDVI (post / pre) % I e j =lax- 4.4 r = p = I I I I I., s'o 6'0 t0 do 90 A/R ratio (post / pre) % Fig 1. Relation between reduction in left ventricular end-diastolic volume index (LVEDVI) and change of the ratio of the peak flow velocity during the atrial kick phase to the peak flow velocity in the rapid filling phase at the level of the mitrai valve (AIR ratio). There is a significant positive correlation (r = ; p = 0.014) between postoperative changes in left ventricular volumes and A/R ratios. This implies that improvement of the A/R ratio is caused mainly by the reduction of ventricular volume after aneurysmectomy.

4 406 KAWATA ET AL Ann Thorac Surg CARDIAC PERFORMANCE AFTER PATCH RECONSTRUCTION 1995;59:403-7 contractile ~ [~tlon portion [ aneurysmal co;tr~ict~le == apou~smal Fig 2. Application of the hemispheric model. A left ventricular silhouette is divided into aneurysmal and contractile portions. A hemispheric model is applied to each portion. The aneurysmal polo'on is calculated as a cylinder with a width h and a hemisphere with a radius r without changing the surface area of the aneurysmal portion. The aneurysmal surface area (S) and the maximum patch area (P = cross-sectional area) can be expressed as 2~r + 2;rrh and wr 2, when the diastolic volume of the contractile portion is kept unchanged. The patch size can be expressed as S/2 - wrh, which denotes that the patch size should be less than 50% of the aneurysmal wall area to be resected. We analyzed the one-third filling fraction and peak filling rate calculated from radioisotopic angiograms and assessed the AIR ratio by Doppler ultrasonography in patients undergoing patch reconstruction. In the present study, the A/R ratio, one-third filling fraction, and peak filling rate were selected as indices of diastolic function. The A/R ratio seems to be the most useful diastolic index in assessing the time course of cardiac function [9]. However, for this parameter to be valid in comparing diastolic function between different groups, it is necessary for the patient to be in normal sinus rhythm, free from mitral valve disease, and to have a left ventricular end-diastolic pressure less than or equal to 18 mm Hg. The subjects in the present study satisfied all of these requirements. Changes in the A/R ratio from the preoperative to postoperative periods had a significantly positive correlation with changes in LVEDVI (r = ; p = 0.014) (see Fig 1). Furthermore, this ratio greatly improved in the early postoperative period, suggesting that the postoperative reduction in the A/R ratio was a direct effect of aneurysmectomy resulting in a reduction in the LVEDVI. A comparison between 9 patients with concomitant CABG and 7 patients without it revealed that concomitant CABG had no direct effects on reducing the AIR ratio. Changes in One-third Filling Fraction and Peak Filling Rate Radioisotopic studies are very useful for evaluating left ventricular aneurysms because geometric changes of the left ventricular cavity occur after operation and conventional angiographic studies are limited by applying the assumption of an ellipsoid shape. In patients with a left ventricular aneurysm, the preoperative one-third filling fraction and peak filling rate are low, similar to the preoperative levels reported for patients with ischemic heart disease [8]. After operation, both variables improved but remained lower than the normal range. These results suggest that an akinetic area, formed by the patch and residual myocardial fibrosis, probably limits the improvements in these variables, as has been previously reported in patients after myocardial infarction [8]. Patch Size Used for Left Ventricular Reconstruction It is unknown what patch size is the most appropriate to reconstruct the left ventricle following aneurysmectomy. If the size of patch is maximally reduced, it will essentially represent a conventional direct closure, and may deform the left ventricular contour. If the size is kept large enough to maintain the original end-diastolic contour of the contractile portion of the left ventricle, it will remain a large akinetic patch area. According to the hemispheric model by Watson and colleagues [7], and left ventricular geometric analysis with an akinetic area by Kitamura and associates [15], we divided the left ventricular silhouette into aneurysmal and contractile portions (Fig 2). Each portion is assumed to be a hemisphere with a radius r and a cylindrical portion with a width h. The surface area of the aneurysmal portion and the maximal patch area can be expressed as 2-n-r 2 + 2vrrh and wr 2 Therefore, to resect the aneurysrnal portion without changing the volume of the contractile portion at diastole, the area of a patch to be applied should theoretically be less than 50% of the surface area of the aneurysmal region (S/2 - ~rrh). This figure of 50% includes the overlapped suture line of the patch and myocardial scar. Based on this model analysis, although very simplified, we tried prospectively to estimate the patch size to be less than 50% of the resected scar and prepared so using a large Dacron vessel graft. However, in small aneurysms, it was difficult to use the patch that was less than 50% of the resected area. In large aneurysms, it was easy to reduce the area of a patch to less than 50% of the resected area. As a result, the patch actually used in the present series varied from 38% to 76% (mean, 57% -+ 19%) of the surface area of the resected scar, including the area to be used for suturing, depending upon sizes of the resectable free wall scar and the unresected but excluded septal scar. Thus, the actual size of the patch (without the sewing cuff) forming a part of the left ventricular wall was considered to be less than 50% of the resected area. Although this still may be too large in some cases, postoperative systolic and diastolic ventricular functions improved significantly early after the operation and remained so for an extended period after operation. References 1. Jatene AD. Left ventricular aneurysmectomy: resection or reconstruction. J Thorac Cardiovasc Surg 1985;89: Dor V, Saab M, Coste P, Kornaszewska M, Montiglio F. Left ventricular aneurysm: a new surgical approach. Thorac Cardiovasc Surg 1989;37: Cooley DA. Ventricular endoaneurysmorraphy: a simplified repair for extensive postinfarction aneurysm. J Cardiac Surg 1989;4: Kesler KA, Fiore AC, Naunheim KS, et al. Anterior wall left ventricular aneurysm repair. J Thorac Cardiovasc Surg 1992; 103:841-8.

5 Ann Thorac Surg KAWATA ET AL ;59:403-7 CARDIAC PERFORMANCE AFTER PATCH RECONSTRUCTION 5. Salati M, Di Biasi P, Paje A, Santoli C. Left ventricular geometry after endoventriculoplasty. Eur J Cardiothorac Surg 1993;7: Kinoshita S. Radionuclide left ventricular absolute volume determination by ejection fraction measurement data and a left posterior oblique blood pool image. Jpn Heart J 1989;30: Watson LE, Dickhaus DW, Martin RH. Left ventricular aneurysm. Circulation 1975;52: Lee JK, Southee AE, Bautovich GJ, et al. Normalized radionuclide measures of left ventricular diastolic function. Eur J Nucl Med 1989;15: Spirito P, Maron BJ. Doppler echocardiography for assessing left ventricular diastolic function. Ann Int Med 1988;15: Kitamura S, Echevarria M, Kay JH, et al. Left ventricular performance before and after removal of the noncontractile area of the left ventricle and revascularization of the myocardiurn. Circulation 1972;49: , 11. Kitamura S. Magnitude, time course and mechanisms of functional alterations after excision of chronic left ventricular aneurysm or large scarred myocardium following myocardial infarction. J Jpn Assoc Thorac Surg 1976;24:134, Kawachi IG Kitamura S, Kawata T, et al. Hemodynamic assessment during exercise after left ventricular aneurysmnectomy. J Thorac Cardiovasc Surg 1994;94: Kawachi K, Kitarnura S, Kawashima Y, et al. Changes in myocardial oxygen consumption and coronary sinus blood flow before and after resection of the left ventricular aneurysm after myocardial infarction. J Thorac Cardiovasc Surg 1987;94: Hutchins GM, Brawley RK. The influence of cardiac geometry on the results of ventricular aneurysm repair. Am J Pathol 1980;99: Kitamura S, Kay JH, Krohn BG, Magidson O, Dunne EF. Geometric and functional abnormalities of the left ventricle with a chronic localized noncontractile area. Am J Cardiol 1973;31:701-7.