Totally Endoscopic Mitral Valve Repair with Novel Technique of Left Atrial Exposure: Five Years Experience from a Single Center

doi:10.21203/rs.3.rs-4899876/v1

Download PDF

Research Article

Totally Endoscopic Mitral Valve Repair with Novel Technique of Left Atrial Exposure: Five Years Experience from a Single Center

https://doi.org/10.21203/rs.3.rs-4899876/v1

This work is licensed under a CC BY 4.0 License

You are reading this latest preprint version

Background

Endoscopic mitral valve repair has become the standard procedure for the management of isolated mitral regurgitation. Our innovative technique for mitral valve exposure has been previously described. This study evaluates the outcomes of totally endoscopic mitral valve repair using this novel technique over a five-year period at a single center.

Methods

A retrospective review was conducted on 122 patients who underwent totally endoscopic mitral valve repair between May 2018 and December 2023. Clinical and echocardiographic data were meticulously collected and analyzed. The surgical procedure was performed completely endoscopic via a 3–4 cm right mini-thoracotomy, with peripheral cardiopulmonary bypass. A novel technique utilizing retraction sutures for mitral valve exposure was employed. Primary outcomes included the results of the endoscopic techniques, mitral valve repair outcomes, perioperative complications, and short-term mortality. Long-term outcomes, including survival, freedom from reoperation, and recurrent mitral regurgitation, were assessed using Kaplan–Meier analysis.

Results

Mitral valve exposure was successfully achieved in all cases. The mean age of the patients was 54.5 ± 14.2 years, and their mean log EuroSCORE II was 1.53 ± 1.30. The repair rate was 96%, with anterior leaflet repair in 13%, posterior leaflet repair in 69%, and bileaflet repair in 14%. Mean aortic cross-clamp time and cardiopulmonary bypass time were 117 ± 39 minutes and 181 ± 48 minutes, respectively. The early mortality rate was 1,6%. Three patients (2.5%) experienced intraoperative conversion to sternotomy and 6 patients (4.9%) underwent a reoperation. There were 2 cases of stroke (1,6%) and 2 cases of unilateral pulmonary edema (1.6%). The minimum follow-up duration for a patient was 6 months, extending up to 72 months, with a mean follow-up duration of 28.6 ± 15.1 months. Kaplan–Meier analysis demonstrated a 96.7 ± 1.6% survival rate at 5 years, with 98.4 ± 1.2% freedom from reoperation, and 86.1 ± 3.1% freedom from recurrent mitral regurgitation.

Conclusions

Totally endoscopic mitral valve repair utilizing the novel technique of left atrial exposure is feasible and can be safely performed with low mortality and morbidity. This approach achieves a high rate of mitral repair and demonstrates favorable long-term outcomes.

Mitral regurgitation

mitral repair

endoscopic mitral valve repair

mitral valve exposure

retraction sutures

totally endoscopic surgery

Endoscopic mitral valve repair has marked significant milestones in cardiac surgery, offering benefits such as reduced postoperative pain, fewer blood transfusions, shorter ventilation times, reduced lengths of stay in the intensive care unit (ICU) and hospital, improved cosmetic outcomes, and the elimination of the risk of sternitis.^{1, 2} Additionally, continuous advancements in technology and surgical instruments, including the introduction of the 3D endoscopic system and the refinement of surgical tools, have substantially enhanced the effectiveness of the procedure.

In our department, endoscopic mitral valve repair has gained increasing popularity and has become the standard for treating isolated mitral regurgitation (MR). Both short-term and long-term results have been promising, demonstrating the procedure's safety and efficacy.

A critical factor in the success of surgery is the clear exposure of the mitral valve. Among various methods, we have developed and implemented a novel technique for mitral valve exposure. This innovative approach, in line with those reported in previously published studies, has significantly improved our surgical results and patient outcomes.³

This study aims to evaluate the feasibility, safety, and long-term outcomes of totally endoscopic mitral valve repair (TEMVR) utilizing this novel technique for left atrial exposure, based on five years of experience from a single center.

Patient selection and data collection

This is a retrospective, observational study that collected data from 122 consecutive patients who underwent TEMVR for the treatment of isolated MR between May 2018 and December 2023. Isolated MR was defined as mitral regurgitation diagnosed without concurrent stenosis. ⁴ Indications for TEMVR included severe MR accompanied by symptoms of heart failure, signs of left ventricular dysfunction, or left ventricular dilation. Exclusion criteria included patients older than 80 years; EuroSCORE II greater than 10%; BMI exceeding 35; chest deformities (such as pectus excavatum and pectus carinatum); spinal deformities (including kyphosis and scoliosis); concomitant coronary artery disease requiring coronary artery bypass grafting; moderate to severe aortic valve regurgitation; ascending aorta aneurysm, dissection, severe calcification, or dilation greater than 45mm; severe calcification or stenosis of the descending aorta, abdominal aorta, or iliac arteries; severe peripheral arterial disease; right lung adhesions due to prior thoracic surgery, chest radiation, or trauma; redo cardiac surgeries; patients requiring emergency surgery; and infective endocarditis with mitral annulus abscess.

Patient demographics, medical history, and operative and in-hospital outcomes were meticulously documented at the time of each patient's admission and during subsequent follow-up visits. All patients underwent intraoperative transesophageal echocardiography to evaluate the success of the valve repair.

Early outcomes assessed included mortality (defined as any death occurring within 30 days post-operation or prior to hospital discharge), failure of the endoscopic technique, perioperative complications, and the rate of successful repair. Late follow-up was defined as exceeding 6 months. Long-term outcomes included mortality, freedom from recurrent MR and reoperation. Patients were evaluated every 4 weeks during the first 6 months post-surgery, and subsequently every 6 months. In instances of more than moderate MR, follow-up was conducted every 1–3 months based on the severity and symptomatic presentation. Recurrent MR was classified as moderate or severe using a 4-point grading scale (trivial, 1; mild, 2; moderate, 3; severe, 4).

All patients had a minimum follow-up period of 6 months. The median follow-up duration was 28.6 ± 15.1 months (interquartile range, 6–72 months). Patients lost to follow-up or who could not be monitored were excluded from the study.

This study received approval from the ethics review committee of the Department of Cardiovascular and Thoracic Surgery and the hospital's ethics committee, which waived the requirement for informed consent due to the study's retrospective nature.

Surgical Technique

This protocol provides a detailed methodology on performing TEMVR using our specialized technique for mitral valve exposure. Induction of conventional general anesthesia was achieved using double-lumen or single-lumen tracheal intubation. The patient was positioned supine with the right side elevated to a 30-degree angle by placing a pillow beneath the axilla. The right upper limb was positioned parallel to the body with the elbow joint slightly flexed to fully expose the right lateral chest. A transesophageal echocardiography probe was inserted, and two external defibrillator pads were placed on the back. Peripheral cardiopulmonary bypass (CPB) was established via the right femoral artery, femoral vein, and right internal jugular vein.

A primary working port was created at the fourth or fifth intercostal space (ICS) with a 3–4 cm incision extending from the mid-axillary line to the anterior axillary line on the right side. Following the incision, a soft tissue retractor was inserted to avoid damage to the ribs and surrounding structures. This working port accommodated all surgical instruments, the cardioplegia needle, the left venting line, and the CO₂ insufflator. A 10-mm trocar for a 3D endoscope (Karl Storz, Tuttlingen, Germany) was inserted through either the fourth or fifth ICS, positioned at the right mid-axillary line. The ascending aorta was cross-clamped using a transthoracic Chitwood clamp through the third ICS at the anterior axillary line. Cardiac arrest was induced by delivering cardioplegia into the ascending aorta.

Upon achieving cardiac arrest, the left atrium was incised, and the mitral valve was exposed utilizing the following retraction sutures: Four 3/0 or 4/0 polypropylene sutures were employed to retract the walls of the left atrium. The sutures were placed at the interatrial septum at the 10 o’clock, 12 o’clock, and 2 o’clock positions, each at least 2 cm away from the anterior mitral annulus. The needles were then threaded through either the pericardium or the anterior thoracic wall, exiting through the working port. This retraction sutures of the interatrial septum provided excellent exposure of the anterior mitral annulus and the lateral trigon. Once these sutures were secured to the surgical drape, the exposure remained stable throughout the entire procedure. An additional suture was placed either at the floor or the posterior wall of the left atrium, then threaded through the right diaphragm. This suture afforded enhanced exposure of the posteromedial commissural area by retracting the left atrium with the posterior annulus. This technique facilitated accurate placement of annuloplasty sutures and minimized the risk of injury to the circumflex artery, which curves towards the posterior mitral annulus. Moreover, this approach brought the mitral valve plane closer to the surgeon, allowing for more space and improved surgical maneuverability.

Once optimal exposure of the mitral valve was achieved, standard mitral valve repair techniques were employed. The repair was conducted under complete 3D endoscopic visualization using standard minimally invasive cardiac surgery instruments.

Statistical Analysis

This study was designed as a retrospective analysis, with data presented as mean ± standard deviation. Survival and event-free estimates were determined using Kaplan-Meier analysis. All Kaplan-Meier analyses were conducted on the total patient cohort of 122 individuals. Three patients who underwent immediate intra-operative conversion to sternotomy were censored on the day of surgery. Statistical analyses were performed using SPSS version 24.0, with P-values < 0.05 considered indicative of statistical significance.

The baseline characteristics of the patient cohort are listed in Table 1. The mean age was 54.5 ± 14.2 years, and 62% of the patients were male. The mean Body Mass Index was 21.88 ± 3.02 kg/m². Within the cohort, 70.5% had a normal BMI, 13.1% were underweight (BMI < 18.5), 15.6% were overweight (BMI 25-29.99), and 0.8% were classified as obese (BMI ≥ 30). The mean preoperative left ventricular ejection fraction was 69.7 ± 9.9%. The most predominant pathology was degenerative disease (n = 109, 89%), followed by endocarditis (n = 13, 11%). The complexity of mitral valve lesions was categorized as simple (72%), complex (12%), and highly complex (16%). The EuroSCORE II analysis indicated a mean score of 1.53 ± 1.30, with 13.1% of patients classified as low risk, 74.6% as medium risk, and 12.3% as high risk.

Table 1

Baseline patient profiles
Characteristic	Value
Mean age, years ± SD (Range)	54.5 ± 14.2 (18–74)
Male, n (%)	76 (62)
Body Mass Index (BMI, kg/m²)
Mean ± SD	21.88 ± 3.02
Range	14.2–30.08
Normal BMI	86 (70.5%)
Underweight (BMI < 18.5)	16 (13.1%)
Overweight (BMI 25-29.99)	19 (15.6%)
Obesity (BMI ≥ 30)	1 (0.8%)
Preoperative Risk Factors
Hypertension	23 (18.9%)
Diabetes mellitus	8 (6.6%)
History of cerebrovascular accident	3 (2.5%)
Chronic kidney disease (Stage 2)	18 (14.8%)
Coronary artery disease (Stented)	6 (4.9%)
Chronic obstructive pulmonary disease	3 (2.5%)
Tuberculosis (Pulmonary/pleural)	2 (1.6%)
Connective tissue disease	1 (0.8%)
NYHA Classification
NYHA I	2 (1.6%)
NYHA II	43 (35.2%)
NYHA III	70 (57.4%)
NYHA IV	7 (5.7%)
Preoperative Echocardiographic Data
Left atrial size (mm)	42.0 ± 7.4
Left ventricular end-diastolic diameter (mm)	57.2 ± 6.6
Left ventricular end-systolic diameter (mm)	34.1 ± 6.8
Ejection fraction (%)	69.7 ± 9.9
Pulmonary artery systolic pressure (mmHg)	41.0 ± 12.7
Mitral valve disease
Degenerative	109 (89%)
Infective endocarditis	13 (11%)
Complexity of Lesions
Simple (one leaflet segment)	88 (72%)
Complex (two segments on one leaflet)	14 (12%)
Highly complex (bileaflet repair, multiple complex techniques)	20 (16%)
EuroSCORE II (%)
Mean ± SD	1.53 ± 1.30
Range	0.56–9.50
Low risk (< 2)	16 (13.1%)
Medium risk (2–5)	91 (74.6%)
High risk (> 5)	15 (12.3%)

Mitral valve repair

Among the 122 candidates for mitral valve repair, 117 (95.9%) underwent successful repairs, while 5 (4.1%) required valve replacement following an attempted repair. The predominant technique employed was annuloplasty, utilized in 109 patients (89.3%). For anterior leaflet repair, the main technique was chordae replacement, performed in 14 patients (11.5%). Posterior leaflet repair was the most frequently performed procedure, applied in 85 patients (69.7%). The main approaches for posterior leaflet repair included triangular resection in 28 patients (23.0%), quadrangular resection in 24 patients (19.7%), and folding repair in 27 patients (22.1%). Bileaflet repair was conducted in 17 patients (13.9%), utilizing techniques such as Alfieri edge-to-edge in 2 patients (1.6%), plication commissure in 8 patients (6.6%), chordae replacement in 4 patients (3.3%), and leaflet resection in 6 patients (4.9%). Postoperative outcomes indicated minimal residual MR at discharge, with 64 patients (55.2%) exhibiting no MR, 43 patients (37.1%) presenting with mild MR, and 9 patients (7.7%) showing moderate MR. Notably, no patients had severe MR at discharge (Table 2).

Table 2

Mitral valve repair techniques
Characteristic	Value
Mitral Valve Repair
Anterior leaflet repair	15 (12.3%)
Posterior leaflet repair	85 (69.7%)
Bileaflet repair	17 (13.9%)
Repair Techniques for Anterior Leaflet
Chordae replacement	14 (11.5%)
Cleft closure	2 (1.6%)
Leaflet patch repair	1 (0.8%)
Excision of vegetation	2 (1.6%)
Repair Techniques for Posterior Leaflet
Triangular resection	28 (23.0%)
Quadrangular resection	24 (19.7%)
Folding repair	27 (22.1%)
Leaflet edge suturing	6 (4.9%)
Excision of vegetation	3 (2.5%)
Annular calcification removal	1 (0.8%)
Repair Techniques for Bileaflet
Alfieri Edge-to-edge	2 (1.6%)
Plication commissure	8 (6.6%)
Chordae replacement	4 (3.3%)
Leaflet resection	6 (4.9%)
Leaflet edge suturing	5 (4.1%)
Excision of vegetation	2 (1.6%)
Ring Annuloplasty	109 (89.3%)
Failed repair (required replacement)	5 (4.1%)

Intraoperative Findings

The learning curve associated with CPB time and aortic cross-clamp time across consecutive operations is illustrated in Figs. 1 and 2, respectively. In Fig. 1, the mean CPB time was 181 ± 48 minutes, with a range from 104 to 338 minutes. The scatter plot, accompanied by a red trend line, demonstrates a consistent reduction in CPB time over the series of operations, reflecting enhanced efficiency and proficiency. Similarly, Fig. 2 shows a mean aortic cross-clamp time of 117 ± 39 minutes, ranging from 54 to 255 minutes. The trend line in the scatter plot signifies a decrease in cross-clamp times with increased surgical experience.

Several intraoperative observations were recorded: right pleural adhesions were identified in 5 patients (4.1%) and pericardial adhesions were observed in 1 patient (0.8%). Among these cases, 3 patients presented with severe pleural adhesions that could not be safely dissected, necessitating conversion to sternotomy (2.5%). Additionally, one patient experienced a complication during the establishment of peripheral CPB, resulting in a perforation of the right internal jugular vein (0.8%). Furthermore, one patient developed systolic anterior motion (SAM) following mitral valve repair (0.8%), necessitating immediate intraoperative re-repair of the valve (Table 3).

Table 3

Intraoperative details
Operative Times	Value
Mean aortic cross-clamp time (min)	117 ± 39
Range (min)	54–255
Mean CPB time (min)	181 ± 48
Range (min)	104–338
Intraoperative Findings
Right pleural adhesions	5 (4.1%)
Pericardial adhesions	1 (0.8%)
Conversion to sternotomy	3 (2.5%)
Right internal jugular vein injury	1 (0.8%)
Systolic anterior motion (SAM)	1 (0.8%)

Early outcomes

The early postoperative outcomes are presented in Table 4. The median ventilation time was 15 hours, with an interquartile range (IQR) of 10 to 59 hours. The median length of stay in the ICU was 2 days, with an IQR of 2 to 4 days. In terms of blood loss and transfusion requirements, 20 patients (16.4%) necessitated blood transfusions, with an average of 0.8 units of red blood cells (RBC) transfused per patient. The median volume of blood loss through drainage was recorded at 300 ml. Several early postoperative complications were documented. The mortality rate was 1.6% (2 patients). Reoperation was required in 5 patients (4.1%) due to bleeding and in 1 patient (0.8%) due to hemolysis. Cerebrovascular accidents (strokes) occurred in 2 patients (1.6%), while new onset atrial fibrillation was observed in 5 patients (4.1%). Renal failure was reported in 6 patients (4.9%), and unilateral pulmonary edema (UPE) was noted in 2 patients (1.6%).

Table 4

Early Outcomes
Characteristic	Value
Ventilation Time and ICU Stay
Ventilation time, hours (median, IQR)	15 (10–59)
ICU stay, days (median, IQR)	2 (2–4)
Early Postoperative Complications
Mortality	2 (1.6%)
Reoperation due to bleeding	5 (4.1%)
Reoperation due to hemolysis	1 (0.8%)
Cerebrovascular accident (stroke)	2 (1.6%)
New onset atrial fibrillation	5 (4.1%)
Renal failure	6 (4.9%)
Unilateral Pulmonary Edema	2 (1.6%)
Pneumonia	6 (4.9%)
Pleural effusion/pneumothorax	11 (9.0%)
Pericardial effusion	3 (2.5%)
Blood Loss and Transfusions
Patients requiring blood transfusion	20 (16.4%)
Mean units of RBC transfused per patient	0.8
Blood loss through drainage, ml (median, range)	300 (40–4600)
Postoperative Echocardiographic Data
Left atrial size (mm)	35.5 ± 6.9
LVEDD (mm)	47.1 ± 6.8
LVESD (mm)	30.9 ± 6.4
Ejection fraction (%)	61.5 ± 9.8
Pulmonary artery systolic pressure (mmHg)	23.5 ± 4.3
No MR	64 (55.2%)
Mild MR	43 (37.1%)
Moderate MR	9 (7.7%)
Severe MR	0 (0%)

Late outcomes

Excluding the 2 early mortality cases, 120 out of 122 patients were followed up regularly for a minimum of 6 months and a maximum of 72 months, with a total follow-up duration of 3408 months and a mean follow-up period of 28.6 ± 15.1 months. The Kaplan-Meier curves demonstrated favorable long-term outcomes for TEMVR. The cumulative survival rate at 72 months was 96.7% ± 1.6%. Freedom from reoperation over the 5-year period post-TEMVR was 98.4% ± 1.2%. For patients who underwent mitral valve repair, freedom from recurrent MR was 86.1% ± 3.1% at the end of the follow-up period (Figs. 3–5).

The advent of minimally invasive mitral valve surgery has conferred numerous benefits to patients. The demand for such less invasive procedures is steadily increasing, driven by the imperative to reduce patient morbidity and enhance recovery. This trend is facilitated by continuous advancements in technology and surgical instruments, all aimed at improving the safety and efficacy of surgery. In this study, we focus on the application of totally 3D endoscopic surgery in mitral valve repair, assessing early and long-term outcomes. Furthermore, we evaluate the feasibility and effectiveness of our novel valve exposure technique—an innovation that represents a significant advancement in our surgical approach.

In our study, the mitral valve repair rate was 96%, with 5 cases (4%) necessitating conversion to prosthetic mitral valve replacement. We classified the complexity of mitral valve lesions to evaluate and predict the likelihood of successful mitral valve repair as follows: simple (annuloplasty alone; single leaflet segment lesion), complex (multiple segment lesions on a single leaflet), and highly complex (bileaflet repair or involving multiple complex techniques, e.g., leaflet patch augmentation, chordal transfer, neochordae replacement). The repair rate for simple lesions was 100%. There were 34 cases categorized as complex and highly complex, representing 28% of the cohort, with a successful repair rate of 85% (29 out of 34 patients) in this group. All instances of repair failure were in the complex anterior leaflet group (4 out of 5 patients) and the highly complex bileaflet group (1 out of 5 patients), with etiologies including infective endocarditis (3 out of 5 patients) and degenerative disease (2 out of 5 patients). Generally, the repair rates in various studies differ significantly, depending on patient selection criteria, lesion morphology, techniques, equipment, and the surgeon's experience. Based on our experience with 122 patients, we propose that certain lesions may not be suitable for the initial implementation of endoscopic mitral valve repair techniques. These include extensive anterior leaflet prolapse involving multiple segments, bileaflet prolapse without commissural involvement, and infective endocarditis.

One of the key factors in determining the success of mitral repair is the adequate exposure of the valve. Numerous instruments have been developed to achieve optimal exposure of the mitral valve in minimally invasive surgery. During the course of our surgical experience, we evaluated various methods and ultimately selected the most suitable approach based on our specific conditions and accumulated expertise. We employed a technique that exclusively utilizes retraction sutures to achieve mitral valve exposure. The materials used for this technique include 3/0 or 4/0 monofilament polypropylene sutures, which are widely accessible. This approach obviates the need for an additional thoracic wall incision, unlike conventional trans-thoracic retractors, thereby mitigating the risks of chest wall bleeding, internal thoracic artery injury, and iatrogenic damage to the leaflet hinge and the bundle of His. Furthermore, employing these sutures ensures that the surgical field remains unobstructed by retractor systems, thus reducing conflicts with surgical instruments. This exposure method is particularly well-suited for a totally endoscopic field, involving a minimal thoracic incision of 3–4 cm, as per our surgical protocol. In instances where the left atrium is small and deviates leftward, the thoracic cavity is deep, or the chest anatomy is unfavorable (e.g., pectus carinatum or pectus excavatum), obtaining satisfactory exposure with a conventional retractor can be challenging. Our technique enables surgeons to place more sutures and select their positions with greater flexibility in blind spots, thereby enhancing visualization. This method was employed in all patients within our study. Mitral valve exposure was successfully achieved in all repair cases and in the five patients who required valve replacement due to complex lesions, which were not related to inadequate exposure. Notably, there were no complications such as tissue tearing requiring additional sutures, ischemic damage, or conversion to sternotomy due to poor visualization.

Several intraoperative complications were observed. Associated with peripheral CPB, a significant complication occurred when the right internal jugular vein and right subclavian artery were perforated during percutaneous cannulation, resulting in substantial bleeding into the pleural cavity. This rare but severe complication necessitated immediate and meticulous intervention. Simple perforations of the internal jugular vein into the pleural cavity can often be managed with endoscopic assistance. However, the concomitant injury to the right subclavian artery presents a risk of acute exsanguination and inadequate CPB flow, potentially requiring conversion to sternotomy and dissection of the sternoclavicular joint to access and control the subclavian artery injury. Our intraoperative management involved maintaining the cannula within the vessel, temporarily controlling the bleeding by suturing the external surrounding tissue, and introducing a new superior vena cava cannula directly through the main working port. Subsequently, the patient underwent endoscopic mitral valve repair as per standard protocol. Immediately following the completion of the surgery, the patient was transferred to the catheterization laboratory. The internal jugular vein cannula was then removed concurrently with angiographic evaluation, during which an arteriovenous fistula involving the right subclavian artery and internal jugular vein was identified. A covered stent was promptly deployed in the subclavian artery, thereby restoring vascular integrity and achieving hemostasis. This endovascular approach facilitated the successful management of this complex complication without necessitating sternotomy or dissection of the sternoclavicular joint.

In our research, 3 patients (2.5%) required conversion to sternotomy: 2 cases due to severe right pleural adhesions and 1 case due to left atrial appendage injury. In global studies, several causes necessitate conversion to sternotomy, including bleeding, pleural adhesions, and aortic dissection. Bleeding can originate from multiple sources such as the pulmonary artery (due to thoracic aortic cross-clamping),⁵ the left atrial appendage (due to Chitwood clamp),⁶ the left ventricular apex (during valve testing), and the ascending aorta (direct cannulation).⁷ Additionally, pleural adhesions frequently necessitate conversion to sternotomy. While pleural adhesions can sometimes be predicted based on a patient’s history of tuberculosis, radiation therapy, or prior surgeries, routine preoperative chest X-rays and CT scans may not always accurately identify these risks. Aortic dissection has also been reported in several studies, predominantly associated with balloon occlusion of the aorta or in patients with underlying atherosclerosis or aortic calcification. Other intraoperative challenges include insufficient peripheral CPB flow,⁸ inadequate valve exposure, and circumflex artery injury,⁷ all of which have been documented and serve as valuable lessons for surgical practice. The two cases requiring conversion to traditional surgery due to pleural adhesions in our study involved challenging adhesiolysis, which resulted in significant pulmonary and pleural injury during the process. The patient with left atrial appendage injury necessitated conversion to sternotomy for control bleeding. However, with the accumulation of surgical experience over time, we have successfully managed this complication via endoscopy in subsequent mitral valve replacement patients.

The early mortality rate in our study was 1.6%, with all affected patients requiring early reoperation. One patient underwent reoperation on postoperative day 3 due to a rupture of the ascending aorta at the site of the cardioplegia needle insertion. This patient experienced hemorrhagic shock and cardiac arrest, necessitating an emergency sternotomy and replacement of the ascending aorta; however, the patient succumbed 24 hours later. The second patient required reoperation on postoperative day 6 due to hemolysis following mitral valve repair (neochordae replacement and annuloplasty). Hemolysis following mitral valve repair is a known complication of prosthetic valve replacement, but its occurrence post-repair is relatively rare and hazardous, with a mortality rate of up to 31%, as reported by Buu Khanh Lam. The mechanisms of hemolysis after mitral valve repair are not fully understood, but several patterns have been proposed, such as fragmentation, collision, rapid acceleration, free jet, and slow deceleration. ^{9, 10} Despite understanding these mechanisms, predicting and early detection of this complication remain challenging. In our study, the patient underwent reoperation and mechanical mitral valve replacement; however, the patient's condition deteriorated due to coagulopathy, hemorrhage, multi-organ failure, septic shock, and ultimately died on postoperative day 22.

In our study, two patients (1.6%) experienced complications of unilateral pulmonary edema (UPE). UPE is an infrequent yet life-threatening condition. Renner et al. reported five instances of UPE following minimally invasive mitral valve surgery over an eight-year period, all necessitating immediate ECMO support. ¹¹ The etiology and pathogenesis of UPE remain ambiguous. Some hypotheses suggest that UPE is a manifestation of permeable pulmonary edema, with prolonged CPB times exacerbating ischemia-reperfusion lung injury.^11–13 Tutschka's research identified prolonged CPB duration, COPD, preoperative pulmonary hypertension, and severe right ventricular dysfunction as significant risk factors for UPE. ¹² Additionally, Keyl emphasized surgical factors, such as the potential for obstruction or stenosis of the right pulmonary vein (caused by excessive traction on the pericardium and sutures used for left atrial exposure) leading to secondary increases in hydrostatic pressure and subsequent right-sided pulmonary edema.¹³ In our cohort, one patient required ECMO support due to UPE. Both patients received intensive care management, including the administration of corticosteroids to mitigate the severity of pulmonary edema. The patient on ECMO was successfully weaned off, and both patients achieved full recovery without any residual sequelae.

In terms of early results, echocardiography at discharge revealed no cases of severe MR. Moderate MR was observed in 9 patients (7.7%), mild MR in 37.1%, and no MR in the majority of patients (55.2%). These findings indicate that TEMVR achieves favorable short-term outcomes with a variety of techniques comparable to the conventional sternotomy approach.

For long-term outcomes, there was one case of mortality at 6 months postoperatively due to infective endocarditis on a bioprosthetic mitral valve. The late survival probability over the 5-year follow-up period was 96.7 ± 1.6%. Two patients experienced severe recurrent MR at 6 and 24 months, necessitating reoperation: one underwent repeat mitral valve repair, and the other required valve replacement. Freedom from reoperation after 5 years was 98.4 ± 1.2%. The probability of freedom from moderate or severe MR at 72 months was 86.1 ± 3.1%.

TEMVR is an effective procedure, yielding favorable early and long-term results with low mortality and morbidity rates. The novel technique for left atrial exposure, associated with totally endoscopic methods, demonstrates substantial feasibility and safety. This approach achieved a high rate of mitral valve repair with excellent early outcomes, minimal recurrent MR, and low rates of reoperation.

Study Limitations

This study included several limitations. Primarily, it is a single-center, retrospective study, which inherently carries the risk of selection bias and may limit the generalizability of the findings to broader populations. Additionally, the absence of a control group undergoing conventional sternotomy precludes direct comparative analysis between the endoscopic approach and traditional surgical methods. Endoscopic mitral valve surgery was only initiated at our center in 2014, and the surgical team's experience with mitral valve repair was still developing during the study period. This nascent phase of experience may have influenced the outcomes observed. Moreover, the follow-up duration for patients in this study was relatively short, with only a limited number of patients being monitored for more than five years. Extended follow-up periods are essential to comprehensively evaluate the durability and long-term efficacy of the endoscopic mitral valve repair technique.

Ethics approval and consent to participate

Availability of data and materials

The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.

Competing interests

The authors declare that they have no competing interests.

Funding

None.

Authors' contributions

T.D: was responsible for the study design, data analysis, and drafting the main parts of the manuscript. TD also served as the lead surgeon performing the procedures, contributed to the interpretation of the results, and participated in the final revision of the manuscript.

C.H: was responsible for data collection, interpretation of the results, and made significant contributions to drafting and revising the manuscript. CH also served as the lead surgeon performing the procedures, participated in the data analysis, and approved the final version of the manuscript.

Acknowledgements

We would like to express our sincere gratitude to the entire surgical team and medical staff at the Cardiovascular Center for their invaluable support during the procedures and data collection for this study. We also extend our thanks to our colleagues and mentors for their guidance and encouragement throughout the research process. Special thanks to the patients who participated in this study for their trust and cooperation. Finally, we are grateful for the administrative and technical assistance provided by the Department of Cardiovascular and Thoracic Surgery, which was essential in completing this work.

Casselman FP, Van Slycke S, Dom H, Lambrechts DL, Vermeulen Y, Vanermen H. Endoscopic mitral valve repair: feasible, reproducible, and durable. The Journal of thoracic and cardiovascular surgery. 2003;125(2):273-282.
Glauber M, Miceli A, Canarutto D, et al. Early and long-term outcomes of minimally invasive mitral valve surgery through right minithoracotomy: a 10-year experience in 1604 patients. J Cardiothorac Surg. Dec 7 2015;10:181. doi:10.1186/s13019-015-0390-y
Pham DT, Le TN, Doan HQ. Innovative techniques of left atrial exposure in minimally invasive mitral valve repair. Asian Cardiovasc Thorac Ann. Mar 2022;30(3):371-373. doi:10.1177/02184923211046698
Waller BF, Howard J, Fess S. Pathology of mitral valve stenosis and pure mitral regurgitation--Part II. Clin Cardiol. Jul 1994;17(7):395-402. doi:10.1002/clc.4960170710
Pfannmüller B, Seeburger J, Misfeld M, Borger MA, Garbade J, Mohr FW. Minimally invasive mitral valve repair for anterior leaflet prolapse. The Journal of Thoracic and Cardiovascular Surgery. 2013;146(1):109-113. doi:10.1016/j.jtcvs.2012.06.044
Vollroth M, Seeburger J, Garbade J, Borger MA, Misfeld M, Mohr FW. Conversion rate and contraindications for minimally invasive mitral valve surgery. Annals of cardiothoracic surgery. 2013;2(6):853-854. doi:10.3978/j.issn.2225-319X.2013.10.15
Perier P, Hohenberger W, Lakew F, Batz G, Diegeler A. Rate of repair in minimally invasive mitral valve surgery. Annals of cardiothoracic surgery. Nov 2013;2(6):751-7. doi:10.3978/j.issn.2225-319X.2013.10.12
Casselman FP, Van Slycke S, Dom H, Lambrechts DL, Vermeulen Y, Vanermen H. Endoscopic mitral valve repair: feasible, reproducible, and durable. J Thorac Cardiovasc Surg. Feb 2003;125(2):273-82. doi:10.1067/mtc.2003.19
Lam B-K, Cosgrove DM, III, Bhudia SK, Gillinov AM. Hemolysis after mitral valve repair: mechanisms and treatment. The Annals of Thoracic Surgery. 2004;77(1):191-195. doi:10.1016/S0003-4975(03)01455-3
Garcia MJ, Vandervoort P, Stewart WJ, et al. Mechanisms of hemolysis with mitral prosthetic regurgitation study using transesophageal echocardiography and fluid dynamic simulation. Journal of the American College of Cardiology. 1996;27(2):399-406.
Renner J, Lorenzen U, Borzikowsky C, et al. Unilateral pulmonary oedema after minimally invasive mitral valve surgery: a single-centre experience. European Journal of Cardio-Thoracic Surgery. 2018;53(4):764-770. doi:10.1093/ejcts/ezx399
Tutschka MP, Bainbridge D, Chu MW, Kiaii B, Jones PM. Unilateral postoperative pulmonary edema after minimally invasive cardiac surgical procedures: a case-control study. Ann Thorac Surg. Jan 2015;99(1):115-22. doi:10.1016/j.athoracsur.2014.07.067
Keyl C, Staier K, Pingpoh C, et al. Unilateral pulmonary oedema after minimally invasive cardiac surgery via right anterolateral minithoracotomy. European Journal of Cardio-Thoracic Surgery. 2015;47(6):1097-1102. doi:10.1093/ejcts/ezu312

No competing interests reported.

Download PDF

Editorial decision: Revision requested
02 Nov, 2024
Reviews received at journal
28 Sep, 2024
Reviews received at journal
28 Sep, 2024
Reviews received at journal
25 Sep, 2024
Reviewers agreed at journal
23 Sep, 2024
Reviewers agreed at journal
20 Sep, 2024
Reviewers agreed at journal
19 Sep, 2024
Reviewers agreed at journal
19 Sep, 2024
Reviewers agreed at journal
18 Sep, 2024
Reviewers agreed at journal
17 Sep, 2024
Reviewers agreed at journal
17 Sep, 2024
Reviewers invited by journal
17 Sep, 2024
Editor assigned by journal
15 Aug, 2024
Submission checks completed at journal
15 Aug, 2024
First submitted to journal
12 Aug, 2024

You are reading this latest preprint version

Totally Endoscopic Mitral Valve Repair with Novel Technique of Left Atrial Exposure: Five Years Experience from a Single Center

Status:

Version 1

Abstract

Figures

Introduction

Materials and methods

Patient selection and data collection

Surgical Technique

Statistical Analysis

Results

Mitral valve repair

Intraoperative Findings

Early outcomes

Late outcomes

Discussion

Conclusions

Study Limitations

Declarations

References

Additional Declarations

Status:

Version 1