Impact of Intubation Time on Survival following Coronary Artery Bypass Grafting: Insights from the Surgical Treatment for Ischemic Heart Failure (STICH) Trial.

OBJECTIVE: The authors aimed to assess determinants of intubation time and evaluate its impact on 30-day and 1-year postoperative survival in Surgical Treatment for Ischemic Heart Failure (STICH) trial patients. DESIGN, SETTING, PARTICIPANTS, AND INTERVENTIONS: A multivariable Cox proportional hazards model was used among the 1,446 surgical patients from the STICH trial who survived 36 hours after operation, in order to identify perioperative factors associated with 30-day and 1-year postoperative mortality. A multivariable logistic regression model was used to determine risk factors associated with intubation time. MEASUREMENTS AND MAIN RESULTS: At 36 hours post-operation, 1,298 (out of 1,446) were extubated and 148 (10.2%) still intubated. Median postoperative intubation time was 11.4 hours. Among patients surviving 36 hours, a multivariable model was developed to predict 30-day (c-index = 0.88) and 1-year (c-index = 0.78) mortality. Intubation time was the strongest independent predictor of 30-day (hazard ratio [HR] 5.50) and 1-year mortality (HR 3.69). Predictors of intubation time >36 hours included mitral valve procedure, New York Heart Association class, left ventricular systolic volume index, creatinine, previous coronary artery bypass grafting (CABG), and age. Results were similar in patients surviving 24 hours post-operation, where intubation time was also the strongest predictor of 30-day (HR 4.18, c-index 0.87) and 1-year (HR 2.81, c-index 0.78) mortality. CONCLUSIONS: Intubation time is the strongest predictor of 30-day and 1-year mortality among patients with ischemic heart failure undergoing CABG. Combining intubation time with other mortality risk factors may allow the identification of patients at the highest risk for whom the development of specific strategies may improve outcomes.

Alternative splicing generates a novel truncated Cav1.2 channel in neonatal rat heart.

L-type Cav1.2 Ca(2+) channel undergoes extensive alternative splicing, generating functionally different channels. Alternatively spliced Cav1.2 Ca(2+) channels have been found to be expressed in a tissue-specific manner or under pathological conditions. To provide a more comprehensive understanding of alternative splicing in Cav1.2 channel, we systematically investigated the splicing patterns in the neonatal and adult rat hearts. The neonatal heart expresses a novel 104-bp exon 33L at the IVS3-4 linker that is generated by the use of an alternative acceptor site. Inclusion of exon 33L causes frameshift and C-terminal truncation. Whole-cell electrophysiological recordings of Cav1.233L channels expressed in HEK 293 cells did not detect any current. However, when co-expressed with wild type Cav1.2 channels, Cav1.233L channels reduced the current density and altered the electrophysiological properties of the wild type Cav1.2 channels. Interestingly, the truncated 3.5-domain Cav1.233L channels also yielded a dominant negative effect on Cav1.3 channels, but not on Cav3.2 channels, suggesting that Cavß subunits is required for Cav1.233L regulation. A biochemical study provided evidence that Cav1.233L channels enhanced protein degradation of wild type channels via the ubiquitin-proteasome system. Although the physiological significance of the Cav1.233L channels in neonatal heart is still unknown, our report demonstrates the ability of this novel truncated channel to modulate the activity of the functional Cav1.2 channels. Moreover, the human Cav1.2 channel also contains exon 33L that is developmentally regulated in heart. Unexpectedly, human exon 33L has a one-nucleotide insertion that allowed in-frame translation of a full Cav1.2 channel. An electrophysiological study showed that human Cav1.233L channel is a functional channel but conducts Ca(2+) ions at a much lower level.

Electrophysiology of human cardiac atrial and ventricular telocytes.

Telocytes (TCs) with exceptionally long cellular processes of telopodes have been described in human epicardium to act as structural supporting cells in the heart. We examined myocardial chamber-specific TCs identified in atrial and ventricular fibroblast culture using immunocytochemistry and studied their electrophysiological property by whole-cell patch clamp. Atrial and ventricular TCs with extended telopodes and alternating podoms and podomers that expressed CD34, c-Kit and PDGFR-ß were identified. These cells expressed large conductance Ca²âº-activated K⁺ current (BK(Ca)) and inwardly rectifying K⁺ current (IK(ir)), but not transient outward K⁺ current (I(to)) and ATP-sensitive potassium current (K(ATP)). The active channels were functionally competent with demonstrated modulatory response to H2 S and transforming growth factor (TGF)-ß1 whereby H2S significantly inhibited the stimulatory effect of TGF-ß1 on current density of both BKCa and IK(ir). Furthermore, H2S attenuated TGF-ß1-stimulated KCa1.1/Kv1.1 (encode BK(Ca)) and Kir2.1 (encode IK(ir)) expression in TCs. Our results show that functionally competent K⁺ channels are present in human atrial and ventricular TCs and their modulation may have significant implications in myocardial physiopathology.

Hydrogen sulphide suppresses human atrial fibroblast proliferation and transformation to myofibroblasts.

Cardiac fibroblasts are crucial in pathophysiology of the myocardium whereby their aberrant proliferation has significant impact on cardiac function. Hydrogen sulphide (H2S) is a gaseous modulator of potassium channels on cardiomyocytes and has been reported to attenuate cardiac fibrosis. Yet, the mechanism of H2S in modulating proliferation of cardiac fibroblasts remains poorly understood. We hypothesized that H2S inhibits proliferative response of atrial fibroblasts through modulation of potassium channels. Biophysical property of potassium channels in human atrial fibroblasts was examined by whole-cell patch clamp technique and their cellular proliferation in response to H2S was assessed by BrdU assay. Large conductance Ca(2+)-activated K(+) current (BK(Ca)), transient outward K(+) current (I(to)) and inwardly rectifying K(+) current (IK(ir)) were found in human atrial fibroblasts. Current density of BK(Ca) (IC50 = 69.4 µM; n = 6), I(to) (IC50 = 55.1 µM; n = 6) and IK(ir) (IC50 = 78.9 µM; n = 6) was significantly decreased (P < 0.05) by acute exposure to NaHS (a H2S donor) in atrial fibroblasts. Furthermore, NaHS (100-500 µM) inhibited fibroblast proliferation induced by transforming growth factor-ß1 (TGF-ß1; 1 ng/ml), Ang II (100 nM) or 20% FBS. Pre-conditioning of fibroblasts with NaHS decreased basal expression of Kv4.3 (encode I(to)), but not KCa1.1 (encode BK(Ca)) and Kir2.1 (encode IK(ir)). Furthermore, H2S significantly attenuated TGF-ß1-stimulated Kv4.3 and α-smooth muscle actin expression, which coincided with its inhibition of TGF-ß-induced myofibroblast transformation. Our results show that H2S attenuates atrial fibroblast proliferation via suppression of K(+) channel activity and moderates their differentiation towards myofibroblasts.

Mitral Annular Disjunction: Clinical Implications and Surgical Considerations.

Mitral annular disjunction is a cardiac structural abnormality characterized by the distinct separation between the top of the left ventricular myocardium and the mitral annulus supporting the posterior mitral leaflet occurring during systole. It has recently gained wide attention due to the increasing recognition of the link between mitral annular disjunction and arrhythmogenic mitral valve prolapse, particularly, with the increased risks of ventricular arrhythmias resulting in sudden cardiac death. This review has summarized the recent progress in the diagnostic modalities, clinical implications of mitral annular disjunction, and its specific surgical considerations.

Isolated Tricuspid Valve Replacement for Infective Endocarditis.

Background: Existing data regarding isolated tricuspid valve replacement for primary tricuspid valve disease such as infective endocarditis (IE) are limited. The aim of this study was to review our experience of isolated tricuspid valve replacement for IE. Methods: A retrospective review was performed to evaluate the perioperative and long-term outcomes of patients undergoing isolated tricuspid valve replacement for IE at our tertiary referral center between January 2000 and December 2014. Surgical outcomes were reviewed to include survival and postoperative complications. Results: Seven patients underwent isolated tricuspid valve replacement for IE during the study period. Mean age was 41 ± 14 years with six (86%) males. Six patients (86%) were intravenous drug users. Five patients (71%) presented with septic emboli to the lungs. Five patients (71%) had active endocarditis at the time of surgery. The indications for surgery were heart failure in three patients (43%), persistent sepsis in three patients (43%) and both in one patient (14%). Methicillin-sensitive Staphylococcus aureus was the most common infective organism, isolated in five patients (71%). There were no in-hospital mortalities or permanent pacemaker implantations. Follow-up was completed in 86% of the cases. The median follow-up period was 13 months (range 2 to 129 months). Three patients (43%) died during the follow-up period, at 7 months, 8 months and 13 months, respectively. All deaths were associated with prosthetic valve IE and recurrent intravenous drug use. Conclusions: This study supplements the paucity of data pertaining to tricuspid valve replacement for IE in the local population. Survival outcomes can be improved with prompt surgical intervention, optimal medical optimization, and a holistic, psychosocial approach targeting intravenous drug abuse.

Clinical presentation of cardiac myxoma in a Singapore national cardiac centre.

INTRODUCTION: Cardiac myxoma is the most common cardiac tumour. In this study, we summarise our 17-year experience with the clinical presentation of cardiac myxoma at National Heart Centre Singapore, Singapore. METHODS: Between January 2000 and December 2016, retrospective data was reviewed for all consecutive patients who underwent surgical resection of cardiac myxoma. Patients' clinical characteristics were reviewed and described. RESULTS: A total of 67 (18 male, 49 female; mean age 53.1 ± 13.5 years) patients underwent cardiac myxoma resection. There were 19 (28.4%) patients with asymptomatic cardiac myxoma. There were no significant differences in gender; body habitus and myxoma size; and haemoglobin, white blood cell or platelet counts between patients with symptomatic and asymptomatic myxoma. However, the number of asymptomatic cardiac myxomas seemed to follow an increasing trend from 19.4% (period 2000-2008) to 36.1% (period 2009-2016), suggestive of an 'era effect'. CONCLUSION: In our study, a majority of patients were women, with a wide age range of 18-78 years. The diagnosis of asymptomatic cardiac myxoma was present in 28.4% of patients, with an increasing trend for incidence over the years. This is possibly due to increased opportunistic screening (with electrocardiography and clinical examination) as well as higher usage of medical imaging.

Long-term prognosis in patients with end-stage renal disease after coronary artery bypass grafting.

BACKGROUND: Cardiovascular disease is a major cause of morbidity and mortality in patients with end-stage renal disease (ESRD). Coronary artery bypass grafting (CABG) is beneficial in selected patients with ESRD. This study investigates the survival outcomes and prognostic factors in ESRD patients who underwent CABG. METHODS: A retrospective analysis was performed for 149 patients with ESRD who underwent isolated CABG between 2006 and 2015. RESULTS: Mean age was 59.4±8.7 years and 106 patients (71.1%) were male. Operative mortality occurred in 20 patients (13.4%). Overall survival was 81.1%±3.2% at 1 year, 41.5%±4.3% at 5 years and 19.2%±4.2% at 10 years. Median survival was 4.3 years. Multivariable analysis identified age [P=0.001, odds ratio (OR): 1.15 per 1-year increase, 95% confidence interval (CI): 1.06-1.25], preoperative left ventricular ejection fraction (LVEF) (P=0.020, OR: 0.94, 95% CI: 0.89-0.99) and non-elective status of operation (P=0.049, OR: 3.34, 95% CI: 1.00-11.1) as predictors of operative mortality. Cox regression analysis identified age [P<0.001, hazard ratio (HR): 1.05 per 1-year increase, 95% CI: 1.03-1.08], New York Heart Association (NYHA) class III or IV status (P=0.010, HR: 1.75, 95% CI: 1.15-2.67) and the use of a left internal mammary artery (LIMA) to left anterior descending artery (LIMA-LAD) graft (P=0.029, HR: 0.42, 95% CI: 0.19-0.92) as factors influencing long-term survival. CONCLUSIONS: CABG is associated with high operative mortality and poor long-term survival in ESRD patients. Age and NYHA class influenced late survival. LIMA-LAD grafting conferred a long-term survival advantage.

Restrictive mitral valve annuloplasty for chronic ischaemic mitral regurgitation: outcomes of flexible versus semi-rigid rings.

BACKGROUND: Restrictive mitral annuloplasty is the mainstay of surgical correction of chronic ischaemic mitral regurgitation (CIMR). Long-term data on the various types of annuloplasty rings is limited. The aim of this study was to investigate the clinical and echocardiographic outcomes of restrictive mitral annuloplasty in patients with CIMR, comparing the use of flexible versus semi-rigid annuloplasty rings. METHODS: A retrospective review was conducted for 133 patients with CIMR who underwent restrictive mitral annuloplasty at our institution between 1999 and 2015. Patient demographics and postoperative outcomes were analyzed. RESULTS: Mean age was 61.9±9.2 years and 103 patients (77.4%) were male. All patients underwent coronary artery bypass grafting, with a mean of 3.3±0.8 grafts. Flexible rings was implanted in 39 patients (29.3%, group F) and semi-rigid rings in 94 (70.7%, group R). Preoperative New York Heart Association class was III/IV in 104 patients (78.2%). Mean preoperative left ventricular ejection fraction was 28.8%±10.2%. Preoperative mitral regurgitation was moderate in 51 patients (38.3%) and severe in 82 (61.7%). In-hospital mortality occurred in 11 patients (8.3%). Overall survival at 1, 5 and 10 years were, respectively, 86.4%, 69.7% and 45.9%. At 10 years, overall survival (group F 53.1%, group R 40.0%, P=0.330) and freedom from moderate to severe MR (group F 53.1%, group R 53.8%, P=0.725) did not differ significantly. Freedom from hospitalization for heart failure was 59.3%. Left ventricular reverse remodelling, defined as a reduction of left ventricular end-systolic volume index >15%, occurred more commonly in Group R (51.1%) compared to Group F (23.1%), P=0.003. CONCLUSIONS: Restrictive mitral annuloplasty was associated with an operative mortality of 8.3%. Heart failure symptoms and significant MR recur in approximately 40% of patients after 10 years. Survival remained suboptimal and was not influenced by the type of annuloplasty ring.

Transection of anterior mitral basal stay chords alters left ventricular outflow dynamics and wall shear stress.

BACKGROUND AND AIM OF THE STUDY: Anterior mitral basal stay chords are relocated to correct prolapse of the anterior mitral leaflet (AML); it has also been suggested that their transection might be used to treat functional ischemic mitral regurgitation. The study aim was to clarify the effect of stay chord transection (SCT) on the hemodynamic aspects of left ventricular outflow. METHODS: Two three-dimensional left ventricular models including the left ventricular outflow tract and saddle-shaped mitral valve before and after SCT were constructed. After SCT, the AML was specified to be more concave and the aortomitral angle to be narrower than before SCT. Time-dependent turbulent flow in a flow range of 10 to 28 l/min during rapid ejection was simulated using the commercial software, FLUENT. RESULTS: Left ventricular outflow before SCT was streamlined along the AML throughout rapid ejection. After SCT, this flow was redirected in the vicinity of the AML, thereby creating a zone of persistent low-momentum recirculation associated with additional energy loss. Consequently, the axial forward flow delivered into the aorta after SCT was diminished. The high wall shear stress, which was concentrated at the fibrous trigones before SCT, was redistributed along the intertrigonal distance after SCT. CONCLUSION: The stay chords, which maintain the natural profile of the AML, are essential to streamline left ventricular outflow, facilitate flow delivery into the aorta, minimize dissipation of potential energy, and to create an optimum wall shear stress pattern that conforms to the fibrous trigones. Transection of the stay chords compromises local hemodynamics, resulting in greater energy loss and unfavorable wall shear stress distribution. The study results emphasize the importance of preserving stay chord function in mitral valve surgeries.

Truly stentless molded autologous pericardial aortic valve prosthesis with single point attached commissures in a sheep model.

OBJECTIVE: Aortic valve cusp extension and free-hand aortic valve replacement with autologous pericardium has been described. The long-term results were shown to be comparable with commercially available aortic bioprostheses. Nevertheless the relatively demanding surgical technique could not find wide acceptance. We developed a new design of a molded aortic valve, fashioned from autologous pericardium, treated briefly with glutaraldehyde, and simplified the implantation technique using single point attached commissures (SPAC). METHODS: Molded autologous valve prostheses were implanted in the subcoronary aortic position in 10 sheep with the commissures connected to the aortic wall at three single commissural points (SPAC). The prosthesis mean size was 21.6+/-1.3 mm and the construction time (excluding 10 min glutaraldehyde treatment) was 6.2+/-1.2 min. Cardiopulmonary bypass and cross-clamp time was 111.1+/-12.4 min and 75.0+/-16.3 min, respectively. Six sheep were euthanized after 201.2+/-10.3 days (6 months) and four sheep were euthanized after 330.8+/-6.5 days (11 months) postoperatively. RESULTS: In all sheep, the valve was immediately competent. At sacrifice, SPAC has proven to be well anchored to the aortic wall and the pericardial valve to be pliable in all cases. The maximum transvalvular gradient after cardiopulmonary bypass and at sacrifice was 3.7+/-2.2 mmHg and 10.6+/-5.2 mmHg, respectively. CONCLUSIONS: This new truly stentless molded autologous aortic valve with simplified implantation technique (SPAC) makes a reliable implantation in a standard timeframe possible. The simplicity of construction, low cost and absent need for anticoagulation of this molded autologous aortic bioprosthesis offers an attractive alternative and not only for patients in the developing world.

Autologous pericardial pulmonary conduit with single point attached commissures in a sheep model.

OBJECTIVE: For the surgical treatment of congenital heart disease and in Ross procedure a valved conduit is frequently required. Since homografts are not readily available in every country, a reliable alternative is needed. We developed a novel technique to construct a valved pulmonary conduit with single point attached commissures (SPAC) in a simple and fast way from a small strip of autologous pericardium, molded and briefly treated with glutaraldehyde. METHODS: Autologous pericardial pulmonary conduit was constructed intraoperatively and implanted in pulmonary position in a beating heart in six sheep. The prosthesis size was 31 mm for all sheep and the construction time (including 10 min glutaraldehyde treatment) was 19.0+/-3.3 min. Implantation time and cardiopulmonary by-pass was 27.3+/-5.4 min and 40.5+/-7.7 min, respectively. The sheep were euthanized after 6 months (222.7+/-5.8 days) postoperatively. RESULTS: In all sheep, the autologous pericardial valve was immediately competent. At sacrifice, the pericardial valve was pliable and competent in all cases with SPAC well anchored to the pericardial conduit wall. The maximum transvalvular gradient at implant and at sacrifice was 3.3+/-2.8 mmHg and 3.3+/-2.0 mmHg, respectively. CONCLUSIONS: This novel autologous pericardial pulmonary conduit with SPAC can be reliably produced in a very short time intraoperatively before cardiopulmonary by-pass. The simplicity of construction, biocompatibility and freedom of stenosis or thrombosis makes this autologous pulmonary conduit especially useful for patients at locations where homografts are not readily available.

Quadriplegia post-coronary artery bypass graft surgery: an unusual case.

A 74-year-old Chinese man with triple-vessel coronary artery disease, developed quadriplegia following coronary artery bypass graft surgery, secondary to cervical disc anterior herniation and a C5-6 to T1 acute spinal hematoma. Preoperatively, no neurological signs or symptoms had been reported.

Paradoxical orthodeoxia in a patient with a large thoracic aortic aneurysm.

INTRODUCTION: Orthodeoxia is a rare clinical syndrome characterised by dyspnoea and arterial deoxygenation that accompanies a change from a supine to erect position. CLINICAL PICTURE: We describe an unusual case of "paradoxical orthodeoxia" in a 70-year-old man with a thoracic aortic aneurysm: arterial desaturation when supine that improved when erect. TREATMENT AND OUTCOME: Non-invasive imaging revealed compression of the left pulmonary artery by the aneurysm (thoracic computed tomography) and patent foramen ovale (transesophageal echocardiography). Nuclear studies show decreased relative left lung perfusion attributable to the former, and right-to-left atrial shunt attributable to the latter. The degree of right-to-left shunt increases in the supine position: nuclear pulmonary shunt study shows shunt extent of 21% when supine versus 10% erect. CONCLUSION: A physioanatomical explanation is proposed.

Successful anticoagulation therapy for a giant left atrial thrombus following mitral valve repair.

A 72-year-old male with atrial fibrillation (AF) underwent mitral valve (MV) repair and concomitant procedures. He was discharged with therapeutic Warfarin dosing but was readmitted 3 weeks later with a right caudate nucleus infarct and subtherapeutic anticoagulation. Echocardiography showed a giant left atrial (LA) thrombus. Low-molecular-weight heparin was promptly initiated. Unfortunately, the patient suffered an intracranial hemorrhage (ICH) 2 days later. He declined surgical thrombectomy and was managed conservatively, remaining stable without neurological deficits. Serial brain imaging showed interval stability, allowing Warfarin to be resumed. Follow-up echocardiography demonstrated partial and complete resolution of the thrombus at 1 and 3 months, respectively.

Primary pulmonary sarcomatoid carcinoma with intracardiac extension.

Primary pulmonary sarcomatoid carcinoma is rare. It is generally regarded as an aggressive tumor. We report, to our best knowledge, the first case of pulmonary sarcomatoid carcinoma with extensive intracardiac spread. This case illustrated the misleading clinical features of this condition. Previous literature is also reviewed.

Surgical management of very late paravalvular leaks after mitral valve replacement: a single institutional experience.

Most mitral paravalvular leaks (PVLs) occur during the first year after mitral valve replacement (MVR). This report describes the surgical management of 6 patients who developed very late mitral PVLs. The median interval between MVR and initial diagnosis of PVL was 16.5 years. All patients presented with congestive cardiac failure and haemolytic anaemia. The median EuroSCORE II was 9.5%. Two patients (33%) had failed attempts at transcatheter closure. Five patients underwent suture repair of the PVL. One patient underwent MVR after removal of the previous prosthesis. No in-hospital mortalities occurred. At latest follow-up (median 3.3 years), 5 patients (83%) were asymptomatic with no residual PVL. Haemolytic anaemia persisted in 1 patient with a mild residual PVL. PVL occurring decades after MVR is a rare but serious complication. Reoperative surgery can be performed in these high-risk patients with satisfactory early and midterm outcomes.

Late Presentation of an Inferior Myocardial Infarction Complicated by Ventricular Septal Rupture: A Case Report.

Ventricular septal rupture (VSR) is a well-described and potentially fatal complication of acute myocardial infarctions. In the era of early reperfusion therapy, the incidence has been on the decline. We describe a case of delayed presentation inferior myocardial infarction complicated by VSR requiring early surgery and review our center's experience.