Anaesthesia for minimally invasive cardiac surgery
2018; Elsevier BV; Volume: 18; Issue: 10 Linguagem: Inglês
10.1016/j.bjae.2018.06.004
ISSN2058-5357
Autores Tópico(s)Cardiac, Anesthesia and Surgical Outcomes
ResumoLearning objectivesBy reading this article, you should be able to:•Discuss the absolute and relative contraindications for minimally invasive mitral valve surgery (MIMVS).•Explain the role of transoesophageal echocardiogram (TOE) and why it is essential in MIMVS surgery.•Summarise the main disadvantages of a ministernotomy compared with conventional full sternotomy for aortic valve surgery.Key points•The term minimally invasive cardiac surgery (MICS) comprises a variety of procedures, the most prevalent of which in the UK are port access mitral valve surgery and minimal-access aortic valve surgery.•Not all patients are suitable; therefore, a thorough preoperative assessment and careful patient selection is essential for good outcomes.•Intraoperative transoesophageal echocardiography plays an essential role in the safe delivery of MICS.•Major benefits include reduced postoperative pain, shorter hospital stay, better cosmesis, and quicker resumption of normal activities.•The anaesthetist must be aware of a range of complications specific to MICS. By reading this article, you should be able to:•Discuss the absolute and relative contraindications for minimally invasive mitral valve surgery (MIMVS).•Explain the role of transoesophageal echocardiogram (TOE) and why it is essential in MIMVS surgery.•Summarise the main disadvantages of a ministernotomy compared with conventional full sternotomy for aortic valve surgery. •The term minimally invasive cardiac surgery (MICS) comprises a variety of procedures, the most prevalent of which in the UK are port access mitral valve surgery and minimal-access aortic valve surgery.•Not all patients are suitable; therefore, a thorough preoperative assessment and careful patient selection is essential for good outcomes.•Intraoperative transoesophageal echocardiography plays an essential role in the safe delivery of MICS.•Major benefits include reduced postoperative pain, shorter hospital stay, better cosmesis, and quicker resumption of normal activities.•The anaesthetist must be aware of a range of complications specific to MICS. Significant advances in cardiac surgery followed the introduction of cardiopulmonary bypass (CPB), which was first established in the early 1950s. Over time, refinements in surgical and anaesthetic techniques combined with improved technology and the use of intraoperative transoesophageal echocardiography (TOE) has enabled less invasive approaches using smaller surgical incisions. Several different approaches can be grouped under the umbrella term 'Minimally Invasive Cardiac Surgery' (MICS), with Cosgrove and colleagues describing the first minimally invasive valve procedures in 1996.1Cosgrove D.M. Sabik D.F. Navia J.L. Minimally invasive valve operations.Ann Thorac Surg. 1998; 65: 1535-1539Abstract Full Text Full Text PDF PubMed Scopus (304) Google Scholar Despite being pioneered more than 20 yr ago, the complex nature of MICS has resulted in only a handful of centres in the UK regularly performing these procedures. Today, MICS encompasses minimally invasive direct coronary artery bypass (MIDCAB), robotic-assisted cardiac surgery, atrial fibrillation (AF) ablation surgery, and minimally invasive approaches to the mitral valve, left and right atria, and aortic valve. Advantages of MICS over a conventional midline sternotomy include reduced postoperative pain, early mobilisation, reduced blood loss, and a shorter hospital stay.2Modi P. Hassan A. Chitwood Jr., W.R. Minimally invasive mitral valve surgery: a systematic review and meta-analysis.Eur J Cardiothorac Surg. 2008; 34: 943-952Crossref PubMed Scopus (340) Google Scholar, 3Falk V. Cheng D.C.H. Martin J. et al.Minimally invasive versus open mitral valve surgery: a consensus statement of the international society of minimally invasive coronary surgery (ISMICS) 2010.Innovations. 2011; 6: 66-76PubMed Google Scholar However, there are a number of potential drawbacks. MICS has been associated with additional complications to those after sternotomy, not all patient groups are suitable, and the surgical skills required to master video-assisted mitral valve repair procedures may involve a substantial learning curve to achieve expertise. MIDCAB surgery describes a minimally invasive approach to coronary artery bypass grafting. This is usually performed using an 'off-pump' technique, avoiding the use of CPB and cardioplegia solution. Access is via a left anterior minithoracotomy plus additional ports, leading to faster recovery times and a shorter intensive care stay.4Zhang L. Cui Z. Song Z. et al.Minimally invasive direct coronary artery bypass for left anterior descending artery revascularisation – analysis of 300 cases.Wideochir Inne Tech Maloinwazyjne. 2015; 10: 548-554PubMed Google Scholar, 7Lee J.D. Srivastava M. Bonatti J. History and current status of robotic totally endoscopic coronary artery bypass.Circ J. 2012; 76: 2058-2065Crossref PubMed Scopus (33) Google Scholar However, it is only suitable for one or two vessel coronary grafting, and careful patient selection is essential. Robot-assisted cardiac surgery first began in 1997 using a simple voiced-activated robot. Current third-generation da Vinci® surgical robots provide high-resolution three-dimensional (3D) imaging, movement scaling, magnification of the surgical field by up to 10-fold, and the option of dual consoles for facilitation of surgical training. Despite the significant startup costs involved ($1.5 million to purchase each system), robotic cardiac surgery is now well established with more than 1700 cases performed annually in the USA.5Pettinari M. Navarra E. Noirhomme P. Gutermann H. The state of robotic cardiac surgery in Europe.Ann Cardiothorac Surg. 2017; 6: 1-8Crossref PubMed Scopus (33) Google Scholar, 6Murkin J.M. Ganapathy S. Anaesthesia for robotic heart surgery: an overview.Heart Surg Forum. 2001; 4: 311-314PubMed Google Scholar, 7Lee J.D. Srivastava M. Bonatti J. History and current status of robotic totally endoscopic coronary artery bypass.Circ J. 2012; 76: 2058-2065Crossref PubMed Scopus (33) Google Scholar Surgical approaches to AF ablation have developed substantially in the past decade. Long within the cardiologist's domain, catheter ablation by pulmonary vein isolation alone has been found to have inferior success rates for conversion to sinus rhythm than a surgical approach. There are many ways to achieve surgical AF ablation. Bilateral video-assisted thoracoscopic surgery (VATS) incisions, with or without the support of CPB, are possible, using mainly bipolar radiofrequency techniques, or a hybrid approach using both surgical and percutaneous endocardial catheter ablation by both surgeon and cardiologists in the same procedure. With a surgical approach, rates of sinus rhythm restoration at 12 months can be as high as 93%, with low complication rates and mortality.8Gon Je H. Shuman D.J. Ad N. A systematic review of minimally invasive surgical treatment for atrial fibrillation: a comparison of the Cox-Maze procedure, beating-heart epicardial ablation, and the hybrid procedure on safety and efficacy.Eur J Cardiothorac Surg. 2015; 48: 531-541Crossref PubMed Scopus (67) Google Scholar The scope of this topic alone warrants its own review article. This describes cardiac surgery performed via a right anterolateral VATS (approx. 4 cm) incision plus accessory ports, using video-assisted ('keyhole') camera technology; it was first reported by Carpenter and colleagues in 1996.9Carpenter A. Loulmet D. LeBret E. et al.Open heart surgery under videosurgery and minithoracotomy: first case (mitral valvuloplasty) operated with success.C R Acad Sci III. 1996; 319: 219-223PubMed Google Scholar The lesions amenable to this approach are listed in Table 1. Mitral regurgitation requiring MV repair surgery is by far the most common lesion encountered and accounts for a large proportion of the published patient data. A commonly used term for this procedure is minimally invasive mitral valve surgery (MIMVS), but the technique does encompass all the procedures in Table 1. We shall henceforth refer to this technique as MIMVS, for clarity.Table 1Summary of differences between two different MICS approachesRight anterolateral VATS/minithoracotomyMinimal access aortic valve replacementLesions appropriateMitral regurgitationTricuspid RegurgitationMyxomaASD/PFOAtrial fibrillationAortic stenosisProcedures possibleMV repair or replacementTV repair or replacementResection of myxoma (L & R atria)ASD/PFO closureAF ablation + LAA clip (bilateral VATS procedure)AV replacement or repairAscending aorta replacementCardiopulmonary bypass cannulaeFemoral venous and arterialFemoral or DirectAortic cross clamping techniqueEndoclamp balloon via femoral arterial cannulaDirect aortic cross clamp (Chitwood)Direct aortic cross clampMV, mitral valve; TV, tricuspid valve; AV, aortic valve; L, left; R, right; ASD, atrial septal defect; PFO, patent foramen ovale; AF, atrial fibrillation; LAA, left atrial appendage. Open table in a new tab MV, mitral valve; TV, tricuspid valve; AV, aortic valve; L, left; R, right; ASD, atrial septal defect; PFO, patent foramen ovale; AF, atrial fibrillation; LAA, left atrial appendage. Access to the heart and major vessels is via an incision at the fourth or fifth intercostal space, or transareolar incision around the nipple, with lung isolation allowing collapse of the right lung. These cases have the most differences to a sternotomy case for the anaesthetist, and hence, anaesthesia for MIMVS warrants a thorough explanation. MIMVS cases encompass a number of features not usually encountered in cardiac surgery. Therefore, effective team working between the perfusionist, anaesthetist, surgeon, and operating theatre staff is essential. For the anaesthetist, a number of specific steps differ from a conventional sternotomy approach. These include the necessity of one-lung ventilation (OLV), use of cerebral oximetry, additional large-bore jugular vascular access, and advanced skills in TOE. For the perfusionist, there are many differences. Peripheral cannulation for CPB is inherently more dangerous than direct cannulation of the aorta and vena cavae. A vacuum is used to assist venous drainage, which can cause air locks or haemolysis. Effective arrest of the heart is dependent on achieving good aortic occlusion with the aortic clamping method chosen. If an endoballoon clamping method is being used to deliver cardioplegia, the process of inflation of the balloon and delivery of cardioplegia is technically more demanding for the perfusionist. Also, the use of CO2 to flood the surgical field throughout the procedure is mandatory, as deairing of the heart is harder to achieve at the end of surgery. Overall, MIMVS procedures are safe and effective, with no significant difference found in mortality between MIMVS and conventional approaches for mitral surgery.3Falk V. Cheng D.C.H. Martin J. et al.Minimally invasive versus open mitral valve surgery: a consensus statement of the international society of minimally invasive coronary surgery (ISMICS) 2010.Innovations. 2011; 6: 66-76PubMed Google Scholar The locations on the chest wall of some of the surgical incision sites are shown in Fig 1, Fig 2, Fig 3. The main differences in approaches to the mitral valve area and aortic valve are also summarised in Table 1.Fig 2Mini-sternotomy incision. Reproduced with permission from Edwards Lifesciences.View Large Image Figure ViewerDownload Hi-res image Download (PPT)Fig 3Right anterior thoracotomy (RAT) incision. Reproduced with permission from Edwards Lifesciences.View Large Image Figure ViewerDownload Hi-res image Download (PPT) Patient selection for MIMVS is essential. Elderly, frail patients may benefit from the less invasive approach. Aortic atheromatous disease and potential length of cross-clamp time may preclude the patient with multiple comorbidities. The cosmetically beneficial results are especially appealing to younger patients. MIMVS is ideally suited to an enhanced recovery approach to patient care. Most patients are expected to recover faster and leave hospital earlier than after a conventional midline sternotomy.1Cosgrove D.M. Sabik D.F. Navia J.L. Minimally invasive valve operations.Ann Thorac Surg. 1998; 65: 1535-1539Abstract Full Text Full Text PDF PubMed Scopus (304) Google Scholar It is possible to discharge younger patients home on the second postoperative day. History, examination, and investigations are reviewed. Preoperative investigations should be tailored to each patient individually but usually include a similar workup to those undergoing sternotomy. These include routine blood tests, ECG, transthoracic echocardiogram (TTE), transoesophageal echocardiogram (TOE), or TTE and TOE, coronary angiography, and pulmonary function tests. Any factors are identified which may make a minimally invasive approach impractical or impossible. A computed tomography (CT) scan of the arterial tree assesses the calibre of femoral arteries and aortic dimensions, and determines the degree of any aortic atheromatous disease. Absolute and relative contraindications to the technique are detailed in Table 2. The pros and cons of premedication should be considered. An 'enhanced recovery' approach avoids sedative premedication for a quicker recovery. Most patients will take a number of cardiac medications, which are managed similarly as for conventional sternotomy procedures. Standard cardiac anaesthesia monitoring is established. Depth of anaesthesia monitoring is useful. Cerebral oximetry should also be considered. Cerebral oximetry uses near-infrared spectroscopy to monitor cerebral venous oxygenation during the procedure via electrodes placed on the forehead. Baselines are set whilst breathing room air, which are typically 60–75%. It allows identification of reduced perfusion to the brain or whole body. Unilateral cerebral hypoperfusion can occur, if an endoballoon device migrates distally and occludes the right brachiocephalic artery. When selective anterograde cerebral perfusion is being instituted via the right subclavian artery, usually for aortic arch surgery, cerebral oximetry can detect the rare instance of an aberrant right subclavian (Lusorian) artery. Bilateral cerebral venous desaturation is a surrogate of whole body hypoperfusion, as seen when flows are decreased before surgical manipulations. Cerebral oximetry is discussed further in the section on complications. External defibrillation pads should always be placed on the chest for MIMVS and minimally invasive aortic procedures, as use of internal defibrillation paddles is not possible. Occasionally, paediatric-sized paddles may fit around the heart in a ministernotomy approach. The empty right lung field in a MIMVS case will cause increased transthoracic impedance, impairing current flow. Therefore, temporary reinflation of the right lung is necessary if defibrillation is required. If an intra-aortic endoballoon approach is to be used for aortic clamping, then bilateral radial arterial cannulae will be necessary to monitor migration of the balloon distally to the brachiocephalic trunk/innominate artery (see Fig 4, Fig 5). Hence, invasive pressure monitoring should include four transducers to encompass two arterial lines, CVP and a transducer for the tip of the endoballoon. The anaesthetic monitor display ideally has overlaid waveforms of all of these.Fig 5The Edwards Lifesciences IntraClude II endoballoon device.View Large Image Figure ViewerDownload Hi-res image Download (PPT) After preoxygenation, anaesthesia is typically induced using a combination of short-acting opioid and propofol, followed by neuromuscular block. To facilitate OLV, a double-lumen tracheal tube is usually placed and checked as for any standard thoracic lung isolation case. In the context of a difficult airway, a single-lumen tube with a bronchial blocker is an adequate alternative. Some centres use a single-lumen tube and commence CPB before opening the chest. Anaesthesia is then maintained using either a volatile agent or propofol infusion. Monitoring of core temperature using a bladder temperature catheter in addition to a peripheral nasopharyngeal temperature probe is important. Hypothermia during CPB may be required, which allows flow rates to be decreased and an assumed degree of extra cerebral protection. Cooling of the patient is commenced if high pressures result from the blood flow rate in the femoral arterial cannula, or if the cerebral oximetry suggests poor cerebral perfusion. Forced air warmers or underbody warming blankets plus fluid heating systems should be used to maintain normothermia after separation from bypass. Routine antibiotic prophylaxis should be administered before skin incision. The role of TOE in cardiac surgery is now well established with evidence showing it can reduce cardiovascular complications.10Aybek T. Doss M. Abdel-Rahman U. et al.Echocardiographic assessment in minimally invasive mitral valve surgery.Med Sci Monit. 2005; 11: 27-32Google Scholar MIMVS cannot be performed without TOE. The preoperative investigations, including CT and TOE, should have already highlighted contraindications or further pathology. In addition, a further comprehensive perioperative TOE is performed in the anaesthetic room, before insertion of internal jugular vein catheters. Lesions that may prevent proceeding with MIMVS include aortic dilatation or significant regurgitation (Table 2). Additional pathology may require opening of the right heart, in which case the anaesthetist inserts a superior vena cava (SVC) cannula (see vascular access section).Table 2Absolute and relative contraindications to MIMVSAbsolute contraindicationsRelative contraindicationsAneurysm of ascending aorta >40 mmPectus excavatum chest deformitiesNo defined sinotubular junctionPleural adhesionsAortic regurgitation >moderateHistory of chest trauma/rib fracturesInability to use TOE (oesophageal stricture, achalasia)Previous radiotherapyMobile aortic atheromaRedo surgery (but potentially beneficial)Morbid obesityAortic atheromatous plaquesExtreme mitral annular calcification Open table in a new tab If the mitral valve is being repaired, then a full assessment of the mitral valve is performed. The mechanism of mitral regurgitation is elucidated, if not already known, including which leaflets are involved. Mitral annular measurements, the anterior leaflet length, and intertrigonal distance will assist in the surgeon's decision of which size annuloplasty ring to insert. The risk of developing systolic anterior motion (SAM) of the mitral anterior leaflet after repair is also assessed. Left and right ventricular function plus pulmonary artery pressures are measured, to aid in the decision of whether a pulmonary artery catheter is required to guide weaning of inotropic support after the operation. Use of an endoballoon, rather than a direct aortic clamp, is generally not advised if the ascending aorta exceeds 40 mm.11Malik V. Jha A.K. Kapoor P.M. Anaesthetic challenges in minimally invasive cardiac surgery: are we moving in a right direction?.Ann Card Anaesth. 2016; 19: 489-497Crossref PubMed Scopus (10) Google Scholar The ascending and descending aorta are interrogated for atheromatous plaques, which are a contraindication to MIMVS. Destabilisation of a plaque during threading of the wire or placement of the endoballoon could lead to plaque disruption and systemic embolisation. The aortic valve is assessed for competency and the presence of a distinct sinotubular junction, which assists correct positioning of the endoballoon. Demonstration of normal coronary artery anatomy is reassuring, as aberrant anatomy may compromise flow of cardioplegia when using the endoballoon aortic clamp (Fig. 6 and Fig. 6 online video). 3D images of the prolapsing or flail segments of a regurgitant mitral valve are potentially helpful to the surgeon but are not mandatory. The usual method of venous cannulation for left heart procedures is a long, two-stage SVC/inferior vena cava (IVC) cannula, inserted via the femoral vein. However, if the right side of the heart is to be opened to the atmosphere, planned or inadvertently, then air can be entrained into the bypass circuitry, potentially causing a dangerous air lock for the perfusionist. Surgery involving the right atrium would necessitate this, for example tricuspid valve surgery, atrial myxoma, atrial septal defect (ASD), or patent foramen ovale (PFO) repair. In this case, SVC cannulation is required, so that the equivalent of bicaval cannulation is provided for the perfusionist. The right internal jugular vein is preferred for an SVC cannula, as it has a near-linear path to the right atrium. The anaesthetist performs the insertion of this 17F or 14F line during routine central venous catheter insertion. However, the procedure is not without potential complications: those of any large bore cannula. Heparin 10,000 IU i.v. is given before insertion, with placement of the tip at the right atrial/SVC junction confirmed by TOE. Some centres use a retrograde cardioplegia coronary sinus catheter, which is sited by the anaesthetist via the right internal jugular vein using TOE guidance also. Maintaining sterility, the tubing is later connected through the surgical drapes via a Y-connector to the IVC cannula CPB limb. The surgeon should position the patient carefully, with a gel roll or inflatable bag placed under the right hemithorax to open the rib spaces anteriorly. The right arm is carefully padded and secured down and away from the chest to allow access for the surgeon and camera arm. Care should be taken to avoid excessive traction on the brachial plexus. Padding of any pressure points at the elbows, wrists, and heels is ensured. In order to establish CPB, femoral venous cannulation is always performed first, guided by the TOE bicaval view (see Fig. 9 online-only video). This is in contrast to full sternotomy, where the aortic cannula is always inserted first. Full heparinisation must be achieved before CPB cannulae insertion. The surgeons may have scanned the femoral vessels using ultrasound before commencing surgery, in addition to preoperative CT measurements, to assess the patency and calibre of the femoral vessels. Some patient groups have narrow femoral arteries, particularly female smokers, which may impact on the pressures generated in the arterial cannula at full flow. The risks include arterial dissection and haemolysis. If the pressure in the arterial cannula is >300 mm Hg, then the endoballoon, if being used, should be inserted in the opposite groin to the arterial CPB cannula. Once CPB is established, the descending aorta is visualised with TOE for several minutes to rule out aortic dissection. Before diastolic cardiac arrest with cardioplegia, the ascending aorta is clamped. There are two main methods: application of a transthoracic (Chitwood, Scanlan International Inc., Minneapolis, MN) clamp directly across the aorta or inflation of an endoballoon inserted into the ascending aorta via a side-arm on the arterial cannula. The Chitwood clamp may be used safely up to an ascending aorta diameter of 45 mm. Using a Chitwood clamp necessitates a cardioplegia cannula in the ascending aorta, below the clamp, also through the chest wall. The endoballoon, however, allows delivery of cardioplegia down the central port once the balloon is inflated (Fig. 7). Correct placement of an endoballoon is one of the technically demanding points of the procedure, for the surgeon, perfusionist, and anaesthetist; hence, good communication is paramount. In the surgeon's hands, the sensation of the inflating balloon has been likened to 'flying a kite', with the pressure of the blood from the arterial CPB cannula opposing the force of blood being ejected from the heart. The perfusionist manipulates the systemic vascular resistance with a vasopressor to overcome the pressure generated by the ejecting heart whilst the endoballoon is being inflated, but not so much that it forces the balloon proximally towards the aortic valve. The anaesthetist constantly sees the ascending aorta in the TOE midoesophageal aortic valve long-axis view. A sudden unilateral pressure decrease in the right-sided arterial line trace on the monitors may represent distal migration of the balloon occluding the innominate artery, a complication thought to occur in approximately 7% of cases.12Kottenburg-Assenmacher E. Kamler M. Peters J. et al.Minimally invasive endoscopic port-access intracardiac surgery with one-lung ventilation: impact on gas exchange and anaesthesia resources.Anaesthesia. 2007; 62: 231-238Crossref PubMed Scopus (13) Google Scholar Good teamwork allows that anyone in the operating team can alert the loss of the right radial artery trace, in this circumstance. Proximal migration of the endoballoon could lead to reduced delivery of cardioplegia to the coronary vessels and inadequate myocardial protection, whereas distal migration would compromise perfusion of the head and upper limbs. Cerebral oximetry monitoring can be very useful in alerting compromise to cerebral blood flow if migration occurs, but also as a surrogate marker for whole body perfusion. In contrast, the transthoracic Chitwood clamp appears to be cheaper and quicker, and result in fewer complications.1Cosgrove D.M. Sabik D.F. Navia J.L. Minimally invasive valve operations.Ann Thorac Surg. 1998; 65: 1535-1539Abstract Full Text Full Text PDF PubMed Scopus (304) Google Scholar At near-maximal inflation, the walls of the aorta begin to indent with the balloon. At this point adenosine is injected into the aortic root via the endoballoon central port. During the brief resulting asystole, cardioplegia is commenced (see Fig. 8 and Fig. 8 online video). TOE visualisation of the cardioplegia running down the left and right coronary arteries is reassuring. Ventilation is ceased when full CPB is achieved and anaesthetic vapour delivered through the CPB circuit or intravenously. The left atrium is opened, and surgery is performed. Once the left atrium is open, TOE visualisation of the ascending aorta in the midoesophageal views is lost. In select patients a deep transgastric view may allow confirmation that the balloon has not moved. In place of TOE images at this stage, bilateral radial arterial pressures are monitored. Video-assisted 3D technology may be used to perform a mitral repair. When the procedure is completed, TOE assesses deairing of the chambers and the adequacy of the valve repair before separating from CPB (see Figs. 10 & 11 online-only videos). Left and right ventricular function can also be assessed, along with detection of immediate complications such as SAM of the anterior mitral leaflet. As with conventional cardiac surgery, a temporary right atrial or ventricular epicardial pacing wire may be placed at the end of the procedure, before the pericardium is closed, depending on the rate and rhythm after operation and after bypass. These wires may be removed in the same fashion as with a sternotomy procedure. Intraoperative analgesia comprises a combination of short-acting synthetic opioid, morphine, and paracetamol. Infiltration of local anaesthetic, intercostal nerve blocks, or regional block are beneficial. Ultrasound-guided paravertebral block and catheter allow a paravertebral infusion after operation. Selected patients may be suitable for tracheal extubation on table at the end of the procedure, or may be transferred intubated to a critical care area, to be extubated as soon as feasible. If a double-lumen tube has been used, it should be exchanged for a single-lumen tube before the patient leaves the operating theatre. Usual criteria for tracheal extubation apply: normothermia, haemodynamic stability, without significant acidbase disturbance, and appropriate analgesia instituted. The most consistent finding in several studies is a reduction in pain and faster return to normal activity. Patients who have minimally invasive surgery as a second procedure state that recovery was more rapid and less painful than their original sternotomy. A recent consensus statement, based on the limited data available, has suggested comparable short-term and long-term mortality, in-hospital morbidity (renal, pulmonary, cardiac complications, pain perception, and readmissions) and reduced sternal complications, transfusions, postoperative AF, duration of ventilation, and ICU and hospital length of stay.3Falk V. Cheng D.C.H. Martin J. et al.Minimally invasive versus open mitral valve surgery: a consensus statement of the international society of minimally invasive coronary surgery (ISMICS) 2010.Innovations. 2011; 6: 66-76PubMed Google Scholar, 13Cheng D.C. Martin J. Lal A. et al.Minimally invasive verses conventional open mitral valve surgery: a meta-analysis and systematic review.Innovations. 2011; 6: 84-103PubMed Google Scholar However, the complications below are specific to this procedure. Intraoperative conversion to sternotomy may be required, either if TOE findings are unfavourable or to manage intraoperative complications. One study reported that 1% of 3125 MIMVS cases were converted to sternotomy, the main reason being bleeding. The 30-day mortali
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