Asian Cardiovasc Thorac Ann 2003;11:203-207
© 2003 Asia Publishing EXchange Ltd
Deep Pericardial Stitch Enables Hemodynamically Stable Exposure of Beating Heart
Bartlomiej Perek, MD,
Marek Jemielity, MD,
Jadwiga Tomczyk, MD1,
Estilita Camacho, MD1,
Wojciech Dyszkiewicz, MD
Department of Cardiac Surgery, Institute of Cardiology
1 Department of Anesthesiology, Karol Marcinkowski University of Medical Sciences, Poznan, Poland
For reprint information contact: Bartlomiej Perek, MD Tel: 48 61 8549085 Fax: 48 61 8549085 email: bperek{at}yahoo.com Department of Cardiac Surgery, Institute of Cardiology, ul. Dluga 1/2, 61-848 Poznan, Poland.
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ABSTRACT
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The use of a deep pericardial stitch to obtain optimal exposure for precise distal anastomoses was assessed in 51 patients (mean age, 56.5 ± 9.1 years) undergoing off-pump coronary artery bypass grafting. Hemodynamic data were recorded after sternotomy, before, and after each of the 120 distal anastomosis. Most hemodynamic parameters did not change throughout the procedures. During exposure of the circumflex artery, there were significant decreases in systolic arterial pressure from 106.0 ± 15.5 to 87.7 ± 13.6 mm Hg, mean systemic arterial pressure from 83.9 ± 11.7 to 68.5 ± 17.0 mm Hg, stroke volume from 68.5 ± 23.3 to 50.5 ± 18.3 mL, and stroke index from 34.4 ± 11.5 to 24.3 ± 8.7 mL•m-2. Cardiac function was not affected when other coronary arteries were bypassed. On completion of all anastomoses, hemodynamics returned to baseline status. It was concluded that the deep pericardial stitch enabled stable and safe exposure of the heart for off-pump coronary artery grafting.
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INTRODUCTION
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Off-pump coronary artery bypass grafting (OPCAB) through a median sternotomy is becoming more common. In Poland for example, only 94 such operations were performed in 1996, the number increased to 654 in 1998, and reached 1,584 in 2000, accounting for approximately 15% of all direct myocardial revascularization procedures.1 This procedure has prompted the development of new methods and instruments for exposure of the recipient arteries.2,3 Optimal exposure should enable precise distal anastomosis and must not prejudice hemodynamic performance.4 Concerns have been expressed particularly when the beating heart was positioned and stabilized for grafting the circumflex (Cx) and posterior descending (PD) arteries.4,5 To prevent impairment of cardiac function, techniques of mechanical support have been proposed.6 In 1999, we started performing OPCAB surgery using a deep pericardial stitch for appropriate heart exposure, and a stabilizer for immobilization of the distal anastomotic site. The aim of this study was to assess the clinical usefulness and safety of a deep pericardial stitch.
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PATIENTS AND METHODS
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The study group comprised 51 consecutive OPCAB patients (30.9% of all coronary patients) with a mean age 56.5 ± 9.1 years (range, 37 to 76 years). They were operated upon between April and July 2001 by the same experienced cardiac surgeon (MJ) who had performed more than 1,800 coronary operations including 200 off-pump cases. Preoperative patient demographics are outlined in Table 1
. In preoperative coronary angiography, left main involvement was diagnosed in 13 patients (25%), triple-vessel disease in 27 (53%), double-vessel disease in 7 (14%), and single-vessel disease in 4 (8%). Before the operation, the mean ejection fraction was 56.4% ± 13.4% (range, 25% to 77%) and left ventricular end-diastolic pressure was 16.5 ± 6.8 mm Hg (range, 8 to 30 mm Hg).
All operations were performed via a median sternotomy. After opening the pericardium and harvesting the grafts, a deep pericardial stitch was placed halfway between the inferior vena cava and the left inferior pulmonary vein. A swab was stitched to the posterior wall of the pericardial sac, and traction was applied to the ends of the suture to facilitate appropriate exposure of the recipient coronary arteries. When the heart was exposed, the site of distal anastomosis was immobilized using an Octopus III stabilizer (Medtronic, Inc., Minneapolis, MN, USA). The target vessels were occluded proximal to the planned anastomosis by snaring with 4/0 polypropylene loops, the lumen was opened by a longitudinal incision, and intracoronary shunts were introduced (ClearView; Medtronic, Inc., Minneapolis, MN, USA). There were 120 anastomoses: 49 to the left anterior descending artery (LAD), 23 to the Cx, 27 to the right coronary artery (RCA), and 21 to the PD artery (Table 2).
Heart rate (HR) was monitored with external electrodes placed on the back of the patient. The systolic, diastolic, and mean systemic arterial pressures were measured using an angiocatheter introduced into the radial artery. Central venous pressure was monitored with a catheter inserted through the subclavian vein to the right atrium. Mean pulmonary arterial pressure and pulmonary capillary wedge pressure were obtained from a Swan-Ganz catheter installed in the pulmonary artery via percutaneous puncture of the external jugular vein. Cardiac index was calculated from cardiac output measurements using 10-mL boluses of iced (4°C–6°C) saline (0.9%) injected into a Swan-Ganz catheter equipped with in-line injection sensors of the thermodilution injection set. Stroke volume, stroke index, systemic and pulmonary vascular resistance index were recorded after sternotomy (baseline), before (when the heart was exposed and the recipient artery stabilized), and after completion (when the heart was in its natural position) of each distal anastomosis. Heparin was administrated at 200 IU•kg-1 prior to the first anastomosis to achieve an activated clotting time > 300 seconds. On completion of all anastomoses, protamine sulfate was given to reverse the action of heparin. Intraoperative inotropic support with a dopamine infusion was started when systolic arterial pressure dropped below 70 mm Hg. When the HR decreased to < 45 beats•min-1, atropine was administered intravenously. Postoperative data including complications and adverse events during hospital stay were recorded. Clinical diagnostic criteria for perioperative myocardial infarction comprised electrocardiographic findings (new Q waves > 0.04 ms and/or reduction in R waves > 25% in at least 2 leads) and biochemical changes (plasma creatine kinase MB-isoenzyme activity > 100 IU•L-1 and cardiac troponin I levels > 5 µg•L-1).
All continuous variables are expressed as mean ± standard deviation. Quantitative data (hemodynamic parameters) were checked for normality with the Shapiro-Wilk W test. Analysis of variance (ANOVA) was employed for statistical analysis. If ANOVA revealed statistically significant changes, a post-hoc comparison of means (Tukey honest significant difference test for unequal number of samples in group – Spjotvoll/Stoline test) was performed. A p value < 0.05 was regarded as statistically significant. Analyses were carried out using Statistica 6.0 for Windows (StatSoft, Inc., Tulsa, OK, USA).
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RESULTS
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All patients survived the OPCAB procedure and the early postoperative period (first 30 days following surgery). Five patients (9.8%) needed intraoperative inotropic support: infusions of dopamine 2.5 µg•min-1•kg-1 were necessary during distal anastomosis to the Cx in 4 patients, and to the PD artery in one. In all cases, dopamine was discontinued within 5 minutes of completion of the anastomoses. Three patients developed atrial fibrillation during heart exposure prior to the first distal anastomosis. They were treated successfully by electrical cardioversion. In another patient, bradycardia (HR 40 beats•min-1) appeared at the end of the distal anastomosis to the RCA; atropine was injected intravenously in a dose of 0.5 mg, and the heart recovered completely within 3 minutes.
The results of the hemodynamic measurements are shown in Table 3. The HR, diastolic arterial pressure, cardiac index, mean pulmonary arterial pressure, preload and afterload of the left (pulmonary capillary wedge pressure and systemic vascular resistance index) and right ventricle (central venous pressure and pulmonary vascular resistance index) did not change significantly throughout the procedures. Transient changes in systolic arterial pressure (p = 0.0017) and consequently in mean systemic arterial pressure (p < 0.0001) were observed. Post-hoc tests showed systolic and mean systemic arterial pressures decreased significantly only during exposure of the Cx. In addition, there were marked decreases in stroke index (p = 0.0371) and stroke volume (p = 0.0457) compared to baseline during distal anastomosis to the Cx. On completion of all anastomoses, hemodynamics returned to the baseline status.
Two patients required reoperation: one because of excessive bleeding (from a branch of the internal mammary artery), and the other because of chest infection with sternal dehiscence. In two other cases (3.9%), superficial chest wound infections were noted. During hospital stay, one patient developed perioperative myocardial infarction, but without a need for inotropic support or intraaortic balloon pump insertion. He was discharged on the 10th postoperative day in a satisfactory clinical condition. Seven patients (13.7%) had supraventricular arrhythmias including atrial fibrillation in 3 cases (5.9%), which was successfully treated with antiarrhythmic drugs, and premature extrasystolic beats in 4 (7.8%). No other organ complications (respiratory, neurological, or renal) were observed.
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DISCUSSION
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Some years ago at the beginning of the beating heart surgery era, OPCAB operations were reserved for patients with single- or double-vessel disease, and limited to revascularization of the LAD, its diagonal branches, and the RCA.7,8 Experimental animal studies preceding clinical application showed that exposure of the heart for Cx or PD grafting, requiring elevation and rotation of the cardiac apex, produced changes in ventricular geometry, valve deformation, and a decrease in venous return.5,9 Eventually, it led to impairment of ventricular filling and systolic dysfunction.10 Because of the hemodynamic instability, OPCAB was not recommended for patients with triple-vessel disease or lateral wall involvement.11 Technical improvements, new methods of heart exposure, better immobilization of the anastomotic site, introduction of mechanical support devices, and increasing experience extended the indications for beating heart surgery.12–14 Nowadays, OPCAB procedures can be performed safely on high-risk patients.15 In 1999, only 2 patients underwent beating heart coronary surgery in our department; one with LAD occlusion, another with a severely stenotic RCA. In 2001, 30% of all coronary operations were undertaken without cardiopulmonary bypass, including cases of triple-vessel disease, left main trunk stenosis, left ventricular dysfunction (ejection fraction < 35%, left ventricular end-diastolic pressure > 20 mm Hg), and even emergency procedures for angioplasty complications.
In our opinion, 3 criteria should be fulfilled for safe and effective OPCAB: careful manipulation of the heart to facilitate exposure of all target coronary arteries; appropriate immobilization of the recipient vessels to enable precise anastomosis; and preservation of myocardial perfusion distal to the graft to avoid regional dysfunction. Several techniques of heart exposure have been described.2,9,16 Exposure of the LAD and RCA was found to induce only slight hemodynamic changes.2,3,10 This was confirmed by our study. More extensive cardiac deterioration has been noted when the heart is lifted and rotated to expose the PD, Cx, and its marginal branches.3 It was suggested that right heart support might be essential in maintaining stable hemodynamics, thus support devices were advocated and some experimental studies were carried out.5,6 Others claimed that routine use of inotropic agents, Trendelenburg position to enhance venous return, and volume loading could be useful.9,17 We introduced a deep pericardial stitch assuming that the major issues were to preserve normal venous return to the atria and facilitate right ventricular diastolic expansion.5 Venous return could be maintained by applying traction to the swab attached to the posterior wall of the pericardium. In addition, during exposure for all distal anastomosis including Cx and PD, the right ventricle was not pressed (the ends of the swab were clipped to the surgical towel on the side of the assistant), so diastolic expansion was possible. A very similar technique was described by Watters and colleagues2 but in their method, the two limbs of the sutured swab were fixed on the side of the surgeon, and this might cause mechanical interference with diastolic right ventricular movement. Using a deep pericardial stitch, significant hemodynamic dysfunction was still seen while exposing the Cx, in spite of unchanged preload and afterload of both left and right ventricles.
In this study, any impairment of heart performance during exposure of the Cx was transient and completely reversed after the anastomoses; it had no clinical impact on patient outcome. Previous studies demonstrated that this temporary hemodynamic deterioration had no negative influence on neurological, renal, or myocardial status following OPCAB surgery.18–20 It was concluded that a deep pericardial stitch enables stable and safe heart exposure for OPCAB. The transient and well-tolerated cardiac dysfunction during exposure of the Cx is probably without clinical significance.
Presented in part at the 15th Biennial Congress of the Association of Thoracic and Cardiovascular Surgeons of Asia, Mumbai, India, December 6–9, 2001.
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ABSTRACT
Introduction
