Jamshid H. Karimov

Minimally invasive mitral valve surgery via right minithoracotomy

From early experience in cardiac surgery on the mitral valve, access was gained in different ways: through left and right antero-lateral extended thoracotomy for closed and correspondingly for open mitral commissurotomy, from right parasternal access with rib resection, and via median sternotomy. Median sternotomy remains the most common approach for mitral valve procedures, such as replacement or repair, allowing good visualisation, exposure and working field. Applying the largely spread access as median sternotomy, surgeons always wanted to overcome the necessity of large incisions, get a better surgical view, to dissect with better respect to structural integrity and have better aesthetic results. Enhanced understanding of surgical bases and technological development sourced a breakthrough in minimally-invasive approach for mitral valve surgery, offering several advantages such as less postoperative pain, lower morbidity and mortality, faster recovery and shorter hospital stay. In an effort to share the institutional experience in less invasive surgery, this article demonstrates our approach in mitral valve repair through a right minithoracotomy in the 3rd or 4th intercostal space.

Incidence of chest tube clogging after cardiac surgery: a single-centre prospective observational study

OBJECTIVES Chest drainage following cardiac surgery is used to avoid complications related to the accumulation of blood and serous fluid in the chest. We aimed to determine the incidence of chest tube clogging and the role of bedside assessment in identifying the potential for failure to drain. METHODS Data from 150 patients undergoing cardiac surgery using cardiopulmonary bypass from March to October 2011 were prospectively entered into a database. Chest tubes were visually inspected and functionally assessed at four time intervals (Hours 0, 2-4, 6-8 and at removal), defining need for clearance and presence of partial or complete obstruction. RESULTS Complete data were available for 100 patients. We assessed 234 chest tubes: pericardial (n = 158); pleural (n = 76). The incidence of chest tube clogging for the entire group was 36% (any tube completely clogged at any time), with increased prevalence of clogging observed in urgent and reoperative cases and in those with increased intraoperative blood use. Among 51 tubes resulted to have a thrombus formation observed inside the chest tube at removal, 44 were clogged primarily in the internal portion of the tube, meaning that clogging could not be confirmed by simple bedside inspection of the indwelling tube. CONCLUSIONS The chest tubes can become clogged at any time after their placement. The status of urgency, reoperations and use of blood products can be contributing factors increasing the incidence of chest tube clogging. Clinicians likely underestimate the prevalence of this failure to drain, as most clogging occurs in the internal portion of the tube.

Minimally invasive mitral valve surgery through right thoracotomy in patients with patent coronary artery bypass grafts

We report our institutional experience, with 25 consecutive patients with patent coronary artery bypass grafts (71.8+/-12.7 years), who underwent video-assisted minithoracotomic approach for mitral valve surgery. The surgical technique includes: right minithoracotomy, femoral cannulation and hypothermic ventricular fibrillation. Mean preoperative EuroSCORE was 10.2+/-2.4 and mean ejection fraction was 45+/-9%. Operative mortality was 4% (1/25). No patient required a conversion to sternotomy. Procedures performed were: mitral valve repair in 15 patients (60%), replacement in 10 (40%) and associated tricuspid repair in seven (28%). Mean blood transfusion was 1.2 package/patient. No cardiological, neurological, vascular and wound complications were observed. Postoperative major morbidity includes: severe pulmonary dysfunction in two patients (8%) and acute renal failure in one (4%). Mean ICU and hospital stay were 3.4+/-2.9 and 10.6+/-7.9 days. Echocardiographic follow-up (22.8+/-14.9 months) revealed trace or mild mitral valve regurgitation in all the mitral repair patients. When interrogated, all the surviving patients preferred the minithoracotomic approach rather than the sternotomy. In conclusion, minimally invasive right thoracotomy can be safely performed in patients with functioning coronary bypass grafts requiring mitral valve operation. Low blood transfusion, the avoidance of deep wound infection and the high patient satisfaction are the main advantages of this approach.

Cardiac Autonomic Nerve Stimulation in the Treatment of Heart Failure

Research on the therapeutic modulation of cardiac autonomic tone by electrical stimulation has yielded encouraging early clinical results. Vagus nerve stimulation has reduced the rates of morbidity and sudden death from heart failure, but therapeutic vagus nerve stimulation is limited by side effects of hypotension and bradycardia. Sympathetic nerve stimulation that has been implemented in the experiment may exacerbate the sympathetic-dominated autonomic imbalance. In contrast, concurrent stimulation of both sympathetic and parasympathetic cardiac nerves increases myocardial contractility without increasing heart rate. This review assesses the current state of electrical stimulation of the cardiac autonomic nervous system to treat heart failure.

Limitations to Chronic Right Ventricular Assist Device Support

Failure of the right ventricle represents a significant clinical problem and may have different causes, with rates varying between 5% and 50% in patients supported by a left ventricular assist device (LVAD). However, treatment options and device development for right ventricular failure (RVF) have significantly lagged behind those for LVADs. Newer technologies designed or adapted for RV support are needed to provide adequate long-term circulatory support. In this review, we discuss (1) the significance of RVF and its physiologic implications, (2) device constraints affecting treatment options for RVF, and (3) implantable VADs potentially available for RV support.

Median Sternotomy or Right Thoracotomy Techniques for Total Artificial Heart Implantation in Calves

The choice of optimal operative access technique for mechanical circulatory support device implantation ensures successful postoperative outcomes. In this study, we retrospectively evaluated the median sternotomy and lateral thoracotomy incisions for placement of the Cleveland Clinic continuous-flow total artificial heart (CFTAH) in a bovine model. The CFTAH was implanted in 17 calves (Jersey calves; weight range, 77.0-93.9 kg) through a median sternotomy (n = 9) or right thoracotomy (n = 8) for elective chronic implantation periods of 14, 30, or 90 days. Similar preoperative preparation, surgical techniques, and postoperative care were employed. Implantation of the CFTAH was successfully performed in all cases. Both methods provided excellent surgical field visualization. After device connection, however, the median sternotomy approach provided better visualization of the anastomoses and surgical lines for hemostasis confirmation and repair due to easier device displacement, which is severely limited following right thoracotomy. All four animals sacrificed after completion of the planned durations (up to 90 days) were operated through full median sternotomy. Our data demonstrate that both approaches provide excellent initial field visualization. Full median sternotomy provides larger viewing angles at the anastomotic suture line after device connection to inflow and outflow ports.

Building a Bridge to Save a Failing Ventricle: Radiologic Evaluation of Short- and Long-term Cardiac Assist Devices

Heart failure is recognized with increasing frequency worldwide and often progresses to an advanced refractory state. Although the reference standard for treatment of advanced heart failure remains cardiac transplantation, the increasing shortage of donor organs and the unsuitability of many patients for transplantation surgery has led to a search for alternative therapies. One such therapy is mechanical circulatory support, which helps relieve the load on the ventricle and thereby allows it to recover function. In addition, there is increasing evidence supporting the use of mechanical devices as a bridge to recovery in patients with acute refractory heart failure. In this article, the imaging evaluation of various commonly used short- and long-term cardiac assist devices is discussed, and their relevant mechanisms of action and physiology are described. Imaging, particularly computed tomography (CT), plays a crucial role in preoperative evaluation for assessment of candidacy for implantation of a left ventricular assist device (LVAD) or total artificial heart (TAH). Also, echocardiography and CT are indispensable in assessment of complications associated with cardiac devices. Complications commonly associated with short-term assist devices include bleeding and malpositioning, whereas long-term devices such as LVADs may be associated with infection, pump thrombosis, and cannula malfunction, as well as bleeding. CT is also commonly performed for preoperative planning before LVAD or TAH explantation, replacement of a device or one of its components, and cardiac transplantation. Online supplemental material is available for this article.

Overview of current sutureless and transcatheter mitral valve replacement technology

Mitral valve (MV) regurgitation is the most prevalent form of heart valve disease. As it comes to surgical repair or replacement of the diseased valves, the procedure has been established as safe and effective; however, its invasiveness still carries considerable risk of significant morbidity and mortality. With aging comes increased MV dysfunction, and thus minimally invasive technology is rapidly evolving to meet the challenges of older patients’ preoperative comorbidities and risks associated with surgery. In comparison, in high-risk patients with aortic stenosis, percutaneous transcatheter technologies offer a viable alternative to surgery; however, catheter-based procedures for MV disease are limited only to repair. MV surgeries have limitations and carry the potential for serious complications in high-risk elderly patients. A fast, reliable sutureless or catheter-based means of MV replacement is needed. Although transcatheter devices are still only in preclinical testing or developmental stages, the authors here review various sutureless MV and transcatheter-based concepts and devices for MV replacement.

Towards active tracking of beating heart motion in the presence of arrhythmia for robotic assisted beating heart surgery.

In robotic assisted beating heart surgery, the control architecture for heart motion tracking has stringent requirements in terms of bandwidth of the motion that needs to be tracked. In order to achieve sufficient tracking accuracy, feed-forward control algorithms, which rely on estimations of upcoming heart motion, have been proposed in the literature. However, performance of these feed-forward motion control algorithms under heart rhythm variations is an important concern. In their past work, the authors have demonstrated the effectiveness of a receding horizon model predictive control-based algorithm, which used generalized adaptive predictors, under constant and slowly varying heart rate conditions. This paper extends these studies to the case when the heart motion statistics change abruptly and significantly, such as during arrhythmias. A feasibility study is carried out to assess the motion tracking capabilities of the adaptive algorithms in the occurrence of arrhythmia during beating heart surgery. Specifically, the tracking performance of the algorithms is evaluated on prerecorded motion data, which is collected in vivo and includes heart rhythm irregularities. The algorithms are tested using both simulations and bench experiments on a three degree-of-freedom robotic test bed. They are also compared with a position-plus-derivative controller as well as a receding horizon model predictive controller that employs an extended Kalman filter algorithm for predicting future heart motion.

Human Fitting Studies of Cleveland Clinic Continuous-Flow Total Artificial Heart.

Implantation of mechanical circulatory support devices is challenging, especially in patients with a small chest cavity. We evaluated how well the Cleveland Clinic continuous-flow total artificial heart (CFTAH) fit the anatomy of patients about to receive a heart transplant. A mock pump model of the CFTAH was rapid-prototyped using biocompatible materials. The model was brought to the operative table, and the direction, length, and angulation of the inflow/outflow ports and outflow conduits were evaluated after the recipient’s ventricles had been resected. Thoracic cavity measurements were based on preoperative computed tomographic data. The CFTAH fit well in all five patients (height, 170 ± 9 cm; weight, 75 ± 24 kg). Body surface area was 1.9 ± 0.3 m2 (range, 1.6–2.1 m2). The required inflow and outflow port orientation of both the left and right housings appeared consistent with the current version of the CFTAH implanted in calves. The left outflow conduit remained straight, but the right outflow direction necessitated a 73 ± 22 degree angulation to prevent potential kinking when crossing over the connected left outflow. These data support the fact that our design achieves the proper anatomical relationship of the CFTAH to a patient’s native vessels.