Minimally invasive surgery in cardiac masses

Key points

• Today minimally invasive cardiac surgery (MICS) is a good alternative for standard midsternotomy for many cardiac surgeries.

• Indications, technical issues, and the number of centers for MICS are improving.

• Less tissue damage and systemic inflammatory response syndrome (SIRS), less postoperative bleeding and pain, less need for transfusion, shorter hospital stay and early patient return to daily work and also the patients’ satisfaction on small surgical scars are the main advantages of the MICS.

• Longer cardiopulmonary bypass and aortic cross-clamping time requires training courses and learning curves are the major drawbacks of MICS.

• Cardiac myxomas, as the most common heart tumor, are often easily resectable by minimally invasive approaches.

• The clinical outcome of the myxoma resection by MICS is comparable to the standard midsternotomy technique.

• Minimally invasive surgery can play a limited role in metastatic or primary malignant cardiac tumors because of tumor extension, surrounding tissue invasion, and requiring complex reconstructive procedures which is not feasible in most patients.

• Diagnostic tissue biopsy could be easily performed via minimally invasive approaches.

• Complete preoperative evaluation is crucial in selecting the best surgical approach.

• Secondary to the improvements in the cardio-oncology knowledge and minimally invasive approaches, the clinical results of the MICS for cardiac masses are encouraging.

Principals of minimally invasive cardiac surgery (MICS)

The term “minimally invasive cardiac surgery” refers to a form of cardiac surgery performed using specialized surgical instruments through small incisions to minimize tissue damage and inflammation process and also patients’ more satisfaction and quick recovery. Today minimally invasive cardiac surgery (MICS) is a good alternative for standard midsternotomy for many cardiac surgeries . Although the smaller surgical incision scars seem to be the main advantage of this procedure among the general population, the main advantages of this surgical method are less tissue damage and systemic inflammatory response syndrome (SIRS), postoperative bleeding, less need for transfusion, and shorter hospital stay .

This procedure is technically rather more difficult for heart surgeons and requires training courses and learning curves; however, alleviating concerns about the mediastinitis nightmare and the need for reexploration to control bleeding and tamponade after heart surgery are good incentives for heart surgeons to use this minimally invasive method. Today, the use of this method is increasingly being used in different centers, and the results of surgery performed by cardiac surgeons with sufficient experience are comparable to the conventional method . The need for peripheral cannulation and vascular complications with vascular access, limited vision, and lack of access to the entire field of cardiac surgery as well as the relatively long cardiopulmonary bypass (CBP) and cross-clamp time are the drawbacks of this surgical method. According to studies, adding a few minutes to the pump time and myocardial ischemia does not have a major negative impact on patients’ prognosis .

The necessity for extracorporeal circulation and cardiopulmonary bypass (CPB) machine distinguishes minimally invasive cardiac surgery from other noncardiac minimally invasive operations. Upper J-shaped median sternotomy, right or left lateral thoracotomy, and right anterior thoracotomy are the main surgical approaches of MICS incisions that can be utilized based on operation type. For CPB establishment, peripheral femoral artery and venous cannulation are frequently utilized in minimally invasive procedures to diminish surgical incision, increase surgical view, and make surgery easier and safer . Sometimes it is necessary to use percutaneous superior vena cava cannulation through the jugular vein in the neck for optimal venous drainage . For minimally invasive aortic surgery such as aortic valve replacement or repair and aortic root reconstruction, some surgeons preferred to use the central aortocaval cannulation as standard fashion. Upper J-shaped ministernotomy is commonly used in such aorta surgeries in which only one-third of the sternum toward the third intercostal space is opened. This ministernotomy reduces the risk of dehiscence, mediastinitis, postoperative bleeding, and pain and results in a minimal surgical scar . The main advantage of this surgical incision is that it can easily be converted to a full sternotomy in case of unexpected complications, technical challenges, or concomitant procedures without the need to change the patient’s position or create another surgical incision. This procedure can be used for resection of thymoma or papillary fibroelastoma of the aortic valve .

Right anterior thoracotomy is the next common approach for minimally invasive aortic root and aortic valve surgeries. In this approach, a 4–5 cm incision is made in the second intercostal space, allowing the surgeon adequate access without the need for sternum incisions and providing better cosmetic results. Peripheral cannulation is the preferred method for this procedure; however, in some circumstances when there is good exposure, central cannulation can also be used . Mitral valve surgery can also be performed using this approach by an atriotomy incision in the roof of the left atrium in highly selected patients. Two distinct surgical incisions for converting the approach to ministernotomy during intraoperative surgical complication and limitations in patients with a wide-angled ascending aorta are the main disadvantages of this minimal approach. This method can be very useful for the biopsy of middle and anterior mediastinal tumors.

A 4–5 cm incision of the right lateral minithoracotomy is the most common approach in MICS that is often used for different minimally invasive mitral and tricuspid operations, atrial septal defect (ASD), and PAPVC repair. This surgical approach is also very useful for the resection of masses from the right atrium, left atrium, IVC, or right and left ventricles. Peripheral arteriovenous cannulation must be used to establish the CPB. Two-stage femoral cannulas in which to separate lateral cannula holes inserted within both SVC and IVC can be utilized for complete venous system evacuation. Vacuum-assisted venous drainage (VAVD) can be used to facilitate optimal drain of the venous system on CPB machine. This allows the surgeon to use smaller venous cannulas to reduce the risk of vascular access complications. It is preferable to have the SVC vein independently and percutaneously from the right side of the neck through the right internal jugular vein if a total CBP pump is required, such as for surgery on the right heart including the tricuspid valve surgeries, resection of the right atrial tumor, and ASD closure . Double lumen endotracheal tubes for single-lung ventilation are often used in this surgical approach to facilitate the procedures . Special instruments are required to clamp the ascending aorta and induce cardiac arrest in this technique. This may be done either with a specialized surgical instrument named “Chitwood clamp” to occlude the ascending aorta externally or with an endoaortic clamp internally. The EndoClamp method, which passes through the femoral artery, can also be used to temporarily block the outflow of blood from the ascending aorta by filling the special balloon at the tip of EndoClamp, allowing the cardioplegia solution to perfuse the coronary arteries and induce cardiac arrest. Endoaortic clamp is less commonly used nowadays due to its high cost and vascular problems. Since the surgeon’s finger cannot produce secure knots from a tiny thoracotomy incision, this surgical method requires a special instrument called “knot pusher” to securely tie the sutures. Today, the COR-KNOT device (LSI Solutions Victor NY) can be used to facilitate suture tying, which eliminates the need for normal suture tying by the surgeon .

This approach can also be used in selective patients with cardiac masses and preoperative evaluations have a major role in selecting the best surgical technique. Minimally invasive surgery can be a suitable option for patients with malignant tumors and patients with malignancy who are mostly frail with immune system deficiency; however, optimal resection of the mass, patient’s safety, and the outcome must be considered as the primary goals of surgical management. Although this procedure is technically rather more difficult for heart surgeons and requires training courses and learning curves, alleviating concerns about the mediastinitis nightmare and the need for reexploration to control postoperative bleeding and tamponade are good incentives for cardiac surgeons to use this minimally invasive method. Today, MICS is increasingly being used in different centers with comparable results with the conventional methods. Vascular complications secondary to the peripheral cannulation, lack of access to the entire field of cardiac surgery through a small incision, as well as the relatively longer cardiopulmonary bypass (CBP) and cross-clamp time are the drawbacks of this surgical method. However, adding a few minutes to the pump time and myocardial ischemia does not have a major negative impact on patients’ prognosis .

How to use MICS in cardiac tumors

Primary cardiac tumors are uncommon, with more than two-thirds of them being benign and the most prevalent type is atrial myxoma . Primary malignant tumors are extremely rare and frequently presented in later stages of the disease, so in most cases the desired outcome of a cancer surgery cannot be obtained. Myxomas are the most common surgically treatable cardiac tumors, occurring most frequently in the left atrium, sometimes in the right atrium, and rarely in other heart chambers. As a result, excision of these tumors can be accomplished using minimally invasive techniques such as right minithoracotomy .

Fortunately, cardiac myxomas, as the most common heart tumor, are often easily resectable. Since echocardiographic or radiographic images of myxomas are usually typical and often single, and because they are well-defined mass attached with a short base on the atrial septum or adjacent tissues and do not invade adjacent tissues, the heart surgeon can confidently choose a minimally invasive surgical approach to resect these benign tumors . In typical forms of atrial myxoma, the atrial septum adjacent to the tumor must be resected along with the mass and repaired with a patch, often from the patient’s autologous pericardial tissue, which can be easily performed with a minimally invasive procedure using a small lateral thoracotomy incision. In myxoma resection, especially in the minimally invasive method, complete en bloc resection of the mass is very important because this tumor has a very fragile tissue that can be fragmented during resection and lead to embolism and cerebrovascular accident. Therefore it is critical to emphasize that surgeons with sufficient experience in routine MICS are eligible to perform minimally invasive surgery of the cardiac masses .

Minimally invasive surgery can play a limited role in metastatic or primary malignant cardiac tumors. It is usually not possible to perform safe and effective minimally invasive surgery for malignant tumor resection because complete resection of these malignant tumors often requires complex reconstructive procedures and good surgical access to whole parts of the heart and surrounding tissue that is impossible through small incisions. However, minimal approach video-assisted thoracoscopic surgery (VATS) is a well-known diagnostic tool for mediastinal masses and minimally invasive techniques could be very useful for tissue biopsy in mediastinal or cardiac masses when percutaneous methods failed . With improving the cardio-oncology knowledge and minimally invasive cardiac surgery progressive development, we will see more and more good outcomes from minimally invasive approaches in the management of cardiac tumors in the future.

The main drawback of minimally invasive cardiac tumor surgery is the limited access to the whole heart and surrounding tissues. Cardiac tumor surgery might be unpredictable in terms of its extension and nature. Sometimes cardiac masses appear resectable according to the preoperative evaluations and cardiac imaging results but intraoperative findings are completely different and tumor resection is impossible or at least very challenging because of severe adhesions, tumor invasions, or potential coronary arteries involvement. These problems and possible surgical major complications or need for complex reconstructive operation after an invasive cardiac tumor resection may necessitate an unexpected procedure; and therefore, the operation may become so complicated that it is either impossible or at least unsafe to perform with a minimally invasive approach. Furthermore, relatively prolonged CBP pump and cross-clamp duration may affect the surgical result, and leaving a residual tumor worsens the patient’s outcome during minimally invasive techniques . Although reduced tissue damage, surgical bleeding, and inflammatory response might be highly beneficial to patients with malignancy and immune deficiency status, complete and safe excision of the tumor and proper reconstruction of cardiac cavities in excisable malignant tumors are much more critical whereas these objectives may not be feasible with a minimally invasive procedure.

Preoperative evaluations of patients with primary and secondary malignant tumors are very important. One of the major problems that can complicate minimally invasive surgery is the adhesions of lungs to the heart or thoracic wall, which may entirely exclude the possibility of performing minimally invasive surgery . Peripheral cannulation through the femoral vessels can also be challenging due to the presence of pelvic and abdominal masses around the iliac and aortic arteries, as well as the IVC in patients with metastatic tumors.