Advances in cardiac surgery

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Minimally invasive cardiac surgery

Substantial advances in cardiopulmonary perfusion, intracardiac visualization, endoscopic instrumentation, and robotic telemanipulation progress atechnological shift to the minimally invasive heart surgery. Minimally invasive cardiac surgery /MICS/ has not enjoyed a standardized nomenclature. The terms minimally invasive cardiac surgery have suggested reduced size of the incision, the avoidance of a sternotomy, the use of a partial sternotomy or minithoracotomy, or lack of need for cardiopulmonary bypass.

The first minimally invasive valve surgeries was describing by Cosgrove in 1996. In the same year Carpentier performed the first video-assisted mitral valve repair through a minithoracotomy. Carpentier was also the first to perform robotic mitral valve procedure using the Da Vinci®Surgical System .

MICS is divided into the four levels: first is direct vision with miniincision (10-12 cm.), second level is video assisted MISC with micro-incision 4-6 cm. Third is video-directed and robot-assisted with micro or port incisions (1 cm). Highest level presents robotic telemanipulation with port incisions (1 cm). With the rising level, surgeon losts direct vision to the operating field and the image is transferred by the endoscopic camera to the monitor. Also is missing tactile perception of operating organ and tissue. During these operations completely disappeared classical surgical incision and surgery inside body cavities is done by long instruments that are introduced into the thorax through a small incisions in the chest wall (heartport). Aminithoracotomyis an approximately 6 cm incision made between the ribs, eliminating the need for bones to heal postoperatively. The right minithoracotomy has become the standard approach for several cardiac operations. The approach involves a 6–7cm incision in the 3rd or 4th intercostal space in the right chest, and minimizes trauma while allowing excellent access to the heart. Examples of operations that are routinely performed through this incision include mitral valve repair/replacement,atrial septal defect repair, cardiac tumor resection, tricuspid valve repair, atrial fibrillation surgery, or any combination of these procedures. The left minithoracotomy offers minimally invasive access to the heart for procedures that previously required much lengthier incisions. This approach is typically employed for minimally invasiveoff-pump coronary bypassand cardiac resynchronization therapy for heart failure. Hemisternotomy is a partial incision of the breastbone; a hemisternotomy offers an alternative to the median sternotomy or full incision of the breastbone. The smaller incision allows access to the aortic valves for aortic valve replacement surgery, while decreasing the risk of sternal wound complications.

Major cardiac operations are realized on extracorporeal circulation /ECC/ and require large surgical approach to the great intrathoracic vessels. The evolution of ECC towards minimally invasive procedures brought development of technologies and equipments enabling cannulate peripheral vessels. Venous stream is cannulated with one or two thin-walled cannulas. The open heart videothoracoscopic procedures are cannulated by two cannulas. One smaller is introduced through puncture to the right internal jugular vein and used for drainage of the superior vena cava. The second larger cannula is guided through the femoral vein into the inferior vena cava. Bicaval cannulation is required each time when the right atrium is opened, for procedures in the left atrium are not necessary, but it is preferable. Arterial system is cannulated with „3 in 1 cannula". This cannula is inserted to the femoral artery, passes through the abdominal and thoracic aorta to the aortic arch and the tip ends about a centimeter above aortic valve. Special technology enables use this cannula as an endoclamp to exclude the aortic root and heart from the systemic arterial circulation. Also is possible deliver cardioplegic solution through the special lumen and finally proximally placed orifices allowing antegrade systemic perfusion. These cannulas are introduced by the Seldinger technique after exposure of the femoral artery through a 1.5 cm incision placed in the right groin crease. Location of the cannula and its functionality are continuously monitored using transesophageal echocardiography (TEE) using a full monitoring pressures in different parts of the cannula.

Main benefits of minimally invasive approach are cosmetics, short hospital stay, less blood lost, less pain, less morbidity in obese and elderly patients, efficacy. Disadvantages are limited exposure, prolonged surgical times, learning curve and cost.

Minimally invasive heart surgery includes these procedures:

  • MIDCAB (minimally invasive direct coronary artery bypass)
  • Minimally invasive video-assisted thoracoscopic mitral valve replacement, repair. Manual, visual, videoscopic, robotic
  • MICS TVR
  • Minimally invasive aortic valve replacement / MIAVR/
  • ASD Closure
  • MAZE procedure

MIDCAB Patients with atherosclerotic lesions in the Left Anterior Descending (LAD) coronary artery and the Right Coronary Artery (RCA) may benefit from a technique calledMinimallyInvasiveDirect CoronaryArteryBypass (MIDCAB). In contrast with conventional CABG, this procedure is performed via small 8-10 cm inframammary incision made at the 5th intercostal space - limited left or right anterior thoracotomy to gain access to the coronary arteries. As the procedure is done in a confined space usually while the heart is beating and without the use of an extracorporeal circulation (off-pump), surgeons use different methods to slow down and steady the heart. Since it involves a smaller chest incision than conventional CABG and excludes the use the heart-lung machine, this technique has a less complications, less pain after surgery, and more rapid recovery. Following the surgery, the patient is taken to the recovery area for approximately 12 to 24 hours. Total hospital stay is usually about 3 to 4 days.

Minimally invasive video-assisted thoracoscopic mitral valve surgery the entire procedure is done via a 4 cm working port which is situated in the right inframammary groove, usually in the 4thintercostal space. Long shafted instruments are a necessary to perform the operation. Visualization is accomplished with an endoscope through a separate port in the 4thintercostal space at the anterior axillary line. Another port is used for suction and CO2 insufflation. A left atrial retractor is introduced through a stab wound in the 4thintercostal space, just lateral to the right internal mammary artery. A femoral-femoral extracorporeal circulation is used as well as an endo-aortic balloon and antegrade cold crystalloid cardioplegia. The whole procedure is performed using a double lumen endotracheal tube and TEE guidance. Principles of mitral valve repair or replacement are the same as in aconventional mitral surgery.

MICS TVR can be performed as a isolated MICS TVR or as a concomitant procedure with operation on the mitral valve. Minimally invasive approach for TVR is the same as in the mitral valve procedure. Mild hypothermic cardiopulmonary bypass is used by bi-caval cannulation with caval snares to isolate the right atrium. Indications criteria for MICS TVR are equal to criteria for classical approach. They are based on current guidelines.

MIAVR. In 1996, Cosgrove and Sabik described operation of the aortic valve via a right parasternal incision with rib cartilage resection. In an effort to improve exposure of the aortic valve have been developed variations of a hemi- or mini-sternotomy and the right anterior thoracotomy. Currently, the most common approach used for MIAVR is the mini-sternotomy, using a J, inverted T. This approach brings several advantages over other incisions, minimize postoperative pain and minimally affect thoracic cage stability with adequate exposure. In addition, unlike the parasternal approach, the internal mammary artery need not be dissected and ligated. ECC can be performed like a completely peripheral (femoral–femoral), completely central (atrial–aortic) and variations of these (atrial–femoral and atrial–axillary). Special type of MIAVR is transapical transcatheter aortic valve implantation /TA-TAVI/. This procedure requires hybrid operating room with using a portable C-arm fluoroscope. Preoperative CT scan or intra-operative surface echocardiography is used to identify heart apex. Sixth intercostal space is the most common access site. Over the previously determined location of the apex, a 3 cm incision is made. The incision is done over the top of the rib to avoid lesion to the neurovascular bundle. Then a special balloon expandable transcatheter valve from trileaflet bovine pericardium on a metal stent is delivered to the proper position by transapical guide wire.

ASD closure. Atrial septal defect (ASD) is the most common congenital cardiac disorder requiring intervention. In the last time, an increasing number of techniques of video-assisted mini-thoracotomy or full thoracoscopic methods have been described. One of the most used is a video-assisted using femoral cannulation and a small thoracotomy for closure of an ASD. With this method, it is also easy to perform a tricuspid valve operation at the same time if needed.

Skin incision (5- to 6-cm) is made at the level of the fourth intercostal space, in women in the breast fold. The right lung is collapsed and the thoracic cavity is entered through the fourth intercostal space. A soft tissue retractor is placed, and a rib spreader is used only if necessary for adequate vision. A 10-mm trocar is placed through the third intercostal space in the middle axillary line and a 30° high-definition 2D camera is introduced. CO2insufflation is connected to this trocar. ASD closure is done by direct suture or corrected with pericardial patch.

Maze procedure. Atrial fibrillation (AF) affects 3% to 5% of the population older than 65 years and is associated with significant risks of thromboembolism, stroke, congestive heart failure, and death. Dr. Cox, developed a procedure in which lines of electrical block for pulmonary veins are created to isolate and interrupt of all potential macroreentrant circuits. This procedure is called MAZE. Over the past decade, alternative energy sources (cryothermy, radiofrequency, microwave and laser, high frequency ultrasound) and special instruments have been developed and shifted MAZE procedure towards minimally invasive AF ablation surgery. Sternal-sparing, direct vision minithoracotomy, endoscopic and robotic approaches have been described to treat both lone AF and more commonly as concomitant therapy with mitral valve disease. The modern equipment permits provide these procedures without extracorporeal circulation, on a beating heart. The long-term effect of the surgical treatment on maintenance of the sinus rhythm varies between 70 and 90% and depends on the type of arrhythmia and surgical ablation technique. Other minimally invasive procedure closely related to the MAZE procedure is thoracoscopic occlusion of LAA. Left atrial appendage is a major embolic source in patient with AF. This procedure is potentially safe and efficacious to prevent cardioembolic events.

Robotic surgery

Robotic technology has been developed since the 90s and the initial impulse came from the army. The basic idea was to "operate" patients near the front line or on aircraft remotely by a surgeon who sits in the background or the safety of the mainland. Robotic surgery has a telemanipulator character, it means that the movements of the surgeon are transmitted from controls at the surgeons console to the instruments that mimic the movements of their human wrist (wrist-like). In the robotic system is also implemented the following technologies: stereoscopic 3D display, which allows perfect orientation in space, motion transfer hands to the instruments in appropriate proportions and software for removing hands shaking. The whole technical development and the market situation leds to the creation of a single system that is currently used exclusively for robotic surgery in all surgical fields, including heart surgery. It is a system da Vinci®. This system consists of three components that are interconnected by cables to form a unified system. The individual components of the system are: surgical console, operating console and thoracoscopic tower. Compared with other minimally invasive surgery approaches, robot-assisted surgery gives the surgeon better control over the surgical instruments and a better view of the surgical site.

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