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.

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.

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.

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.

2015 Young Surgeon's Award Winner: Long-term Prognosis in Patients with Diabetes Mellitus after Coronary Artery Bypass Grafting: A Propensity-Matched Study.

INTRODUCTION: We aimed to determine the impact of diabetes mellitus (DM) on long-term survival after coronary artery bypass grafting (CABG) in patients with multivessel coronary artery disease. MATERIALS AND METHODS: A retrospective review was conducted for 5720 consecutive patients who underwent isolated first CABG between 1982 and 1999. Outcomes were reviewed to include in-hospital mortality and long-term survival. Mean follow-up was 13.0 ± 5.8 years. To obtain comparable subgroups, 561 diabetic patients were matched with 561 non-diabetic controls based on estimated propensity scores. RESULTS: Mean age was 59.3 ± 9.1 years with 4373 (76.5%) males. Amongst 5720 patients, 1977 (34.6%) had DM. Hypertension and dyslipidaemia were the most common cardiovascular comorbidities, present in 2920 (51.0%) and 2664 patients (46.6%) respectively. Emergency surgery was performed in 563 patients (9.8%). In-patient mortality occurred in 115 patients (2.0%), 48 (2.4%) in the DM group and 67 (1.8%) in the non-DM group, (P = 0.102). In the unmatched cohort, overall 20-year survival rates were 30.9 ± 1.6% in diabetics and 49.2 ± 1.0% in non-diabetics (P <0.001). Freedom from cardiac mortality at 20 years was 56.0 ± 2.0% in diabetics and 68.4 ± 1.0% in non-diabetics (P <0.001). In the propensity-matched group, overall 20-year survival rates were 35.4 ± 2.5% in diabetics and 48.9 ± 2.9% in non-diabetics (P <0.001). Freedom from cardiac mortality at 20 years was 57.8 ± 3.0% in diabetics and 70.2 ± 2.9% in non-diabetics (P = 0.001). Multivariable Cox regression analysis identified age (hazard ratio (HR): 1.03/year), female gender (HR: 1.43), DM (HR: 1.51), previous myocardial infarction (HR: 1.54) and left ventricular ejection fraction (LVEF) <35% (HR: 2.60) as independent factors influencing long-term cardiac mortality. CONCLUSION: Despite low operative mortality, long-term survival and freedom from cardiac death are significantly lower in patients with DM compared to non-diabetics. Aggressive treatment of DM, cardiovascular comorbidities and smoking cessation are essential to improve long-term survival in diabetic patients.

Chordal Reconstruction versus Leaflet Resection for Repair of Degenerative Posterior Mitral Leaflet Prolapse.

OBJECTIVE: To review our experience of mitral valve repair for degenerative posterior mitral leaflet prolapse, comparing the outcomes of chordal reconstruction and leaflet resection. METHODS: From 2000 to 2014, 205 patients underwent successful repair for degenerative posterior mitral leaflet prolapse. One hundred and four (51.5%) underwent leaflet resection (group R) and 98 (48.5%) underwent chordal reconstruction (group C). Follow-up was 96.5% complete with a mean follow-up of 6.1 ± 4.0 years. RESULTS: Mean age was 57.0 ± 11.0 years. Males accounted for 73.8%. Ring annuloplasty was performed in 195 (96.5%). There were no operative mortalities within 30 days. Overall survival was 97.8% ± 1.3% at 7 years. Outcomes at 6 years: freedom from severe mitral regurgitation (group R 97.1% ± 2.0%, group C 100%, P = 0.288), freedom from moderate or severe mitral regurgitation (group R 97.1% ± 2.0%, group C 94.4% ± 5.4%, P = 0.541). Group C patients received larger annuloplasty rings and had significantly lower postoperative transmitral gradients. CONCLUSIONS: Leaflet resection and chordal reconstruction are effective techniques for repair of degenerative posterior mitral leaflet prolapse. Both techniques result in a low incidence of recurrent mitral regurgitation. Chordal reconstruction accommodates larger annuloplasty rings and is associated with lower transmitral gradients.

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.

Surgical management of infective endocarditis: an analysis of early and late outcomes.

OBJECTIVES: To review our experience of surgical management of infective endocarditis (IE) over a 13-year period and analyse the outcomes and associated prognostic factors. METHODS: A retrospective review was conducted for 191 consecutive patients who underwent surgery for native and prosthetic valve endocarditis (PVE) between January 2000 and December 2012. Surgical outcomes were reviewed to include survival and postoperative complications. Follow-up was complete for 172 of 179 patients (96.1%) surviving to hospital discharge, with a mean follow-up of 6.6 ± 3.7 years. RESULTS: Mean age was 47.4 ± 14.9 years with 113 (63.9%) males. Native valve endocarditis was present in 177 patients (92.7%). Sixty-three patients (33.0%) presented with embolic complications. The brain was the most common site of embolism, involving 25 patients (13.1%). Streptococcus viridans was the most common infective organism, isolated in 68 patients (35.7%), followed by Staphylococcus aureus in 30 patients (15.7%). Eighty-seven patients (45.5%) had active endocarditis at the time of surgery. The mitral valve was infected in 136 patients (71.2%), the aortic valve in 66 (34.6%), the tricuspid valve in 29 (15.2%) and multiple valves in 38 (19.9%). Nineteen patients (9.9%) were intravenous drug users (IVDU). Twelve IVDUs (63.2%) suffered from tricuspid valve IE, compared with 7 of 162 patients (4.3%) in the non-IVDU population (P < 0.001). The most common indication for early surgery was intractable cardiac failure. Twelve patients (6.3%) died during the hospital stay for surgical treatment of IE. Logistic multivariate analysis identified preoperative creatinine clearance and stroke as independent predictors of in-hospital mortality. Overall 10-year survival and freedom from valve-related reoperation were 74.8 and 90.3%, respectively. Age, PVE, S. aureus endocarditis and postoperative left ventricular ejection fraction (LVEF) ≤45% were factors influencing long-term survival. CONCLUSIONS: Surgical management of endocarditis continues to be challenging and is associated with significant morbidity and mortality. This report of 191 patients who underwent valve surgery for IE shows that in-hospital mortality is influenced by preoperative renal function and stroke at the time of presentation. The optimal timing for surgery in patients with stroke remains controversial. Long-term survival was negatively influenced by increasing age, moderate to severely impaired LVEF, prosthetic valve IE and S. aureus infection.

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.

Abnormal origin of right coronary artery from left ventricle with bicuspid aortic stenosis.

Anomalous coronary arteries are rare but can lead to serious complications during cardiac operations if not recognized. We report a 55-year-old woman with anomalous origin of the right coronary artery from the left ventricle, and bicuspid aortic valve stenosis. Coronary angiography and computerized tomographic angiography indicated the diagnosis preoperatively. She underwent aortic valve replacement and coronary artery bypass grafting subsequently, with good recovery. One adult and two children with the same right coronary artery anomaly have been reported in the literature. Preoperative diagnosis is essential in these cases, and long-term follow-up is warranted.

Outcome and survival analysis of surgical repair of post-infarction ventricular septal rupture.

BACKGROUND: To review the experience of surgical repair of post-infarction ventricular septal rupture (VSR) and analyze the associated outcomes and prognostic factors. METHODS: Following approval from the Singhealth Centralised Institutional Review Board (reference: 2011/881/C), a retrospective review was performed on 38 consecutive patients who had undergone surgical repair of post-infarction VSR between 1999 and 2011. Continuous variables were expressed as either mean ± standard deviation or median with 25th and 75th percentiles. These were compared using two-tailed t-test or Mann-Whitney U test respectively. Categorical variables were compared using chi-square or Fisher's exact test. To identify predictors of operative mortality, univariate analysis of perioperative variables followed by multivariate analysis of significant univariate risk factors was performed. A two-tailed p-value < 0.05 was used to indicate statistical significance. RESULTS: Mean age was 65.7 ± 9.4 years with 52.6% males. The VSR was anterior in 28 (73.7%) and posterior in 10 patients. Median interval from myocardial infarction to VSR was 1 day (1, 4). Pre-operative intra-aortic balloon pump was inserted in 37 patients (97.8%). Thirty-six patients (94.7%) underwent coronary angiography.Thirty-five patients (92.1%) underwent patch repair. Mean aortic cross clamp time was 82 ± 40 minutes and mean cardiopulmonary bypass time was 152 ± 52 minutes. Coronary artery bypass grafting (CABG) was performed in 19 patients (50%), with a mean of 1.5 ± 0.7 distal anastomoses. Operative mortality within 30 days was 39.5%.Univariate analysis identified emergency surgery, New York Heart Association (NYHA) class, inotropic support, right ventricular dysfunction, EuroSCORE II, intra-operative red cell transfusion, post-operative renal failure and renal replacement therapy (RRT) as predictors of operative mortality. Multivariate analysis identified NYHA class and post-operative RRT as predictors of operative mortality.Ten year overall survival was 44.4 ± 8.4%. Right ventricular dysfunction, LVEF and NYHA class at presentation were independent factors affecting long-term survival. Concomitant CABG did not influence early or late survival. CONCLUSIONS: Surgical repair of post-infarction VSR carries a high operative mortality. NYHA class at presentation and post-operative RRT are predictors of early mortality. Right ventricular dysfunction, LVEF and NYHA class at presentation affect long-term survival. Concomitant CABG does not improve survival.

Percutaneous mitral valve repair with MitraClip for severe functional mitral regurgitation.

A 67-year-old Chinese woman with comorbidities of chronic obstructive lung disease, hypertension and prior coronary artery bypass surgery presented with severe functional mitral regurgitation (MR) and severely depressed left ventricular function. She was in New York Heart Association (NYHA) Class II-III. Due to high surgical risk, she was referred for percutaneous treatment with the MitraClip valve repair system. This procedure is typically performed via the femoral venous system and involves a transseptal puncture. A clip is delivered to grasp the regurgitant mitral valve leaflets and reduce MR. This was performed uneventfully in our patient, with reduction of MR from 4+ to 1+. She was discharged on post-procedure Day 2 and her NYHA class improved to Class I. This was the first successful MitraClip procedure performed in Asia and represents a valuable treatment option in patients with severe MR, especially those with functional MR or those at high surgical risk.

Iliofemoral anatomy among Asians: implications for transcatheter aortic valve implantation.

BACKGROUND/OBJECTIVES: This study aims to examine iliofemoral anatomy and predictors of vessel size and tortuosity in Asian patients as transfemoral transcatheter aortic valve implantation (TAVI) may be limited by the smaller Asian physique. METHODS: Characteristics and vessel dimensions of 549 patients undergoing ultrasonography were reviewed. The minimal luminal diameter (MLD) along the iliofemoral vasculature of each side was identified and the larger of the two sides was used to determine suitability for transfemoral TAVI. RESULTS: The mean age was 66 ± 11 years (68% males). Mean iliac MLD was 7.6 ± 1.7 mm, females smaller than males (7.2 ± 1.7 vs 7.8 ± 1.7, p<0.001). Mean iliac MLD decreased with age: 7.9 ± 1.7 mm, 7.4 ± 1.9 mm and 7.3 ± 1.6mm for ages <70 years, 70-79 years and ≥ 80 years respectively (p=0.038). Mean femoral MLD was 7.0 ± 1.7 mm, females smaller than males (6.3 ± 1.5mm vs 7.3 ± 1.8mm, p<0.001). Females were more likely than males to have iliac and femoral MLD <6mm (20% vs 12%, p=0.019 and 34% vs 21%, p=0.001). Independent predictors of smaller iliofemoral dimensions were female gender, lower body surface area, diabetes mellitus, dyslipidemia and smoking history. Significant iliac tortuosity was present in 11.8%, more frequent in males than females (15% vs 6%, p=0.005), and in those with logistic EuroSCORE ≥ 15 than <15 (27% vs 10%, p=0.001). CONCLUSIONS: This study establishes the mean iliac and femoral artery diameters in a cohort of relatively young Asian patients. Age and female gender were associated with smaller vessel dimension and several independent predictors of smaller vasculature and tortuosity were identified. These results have implications for TF TAVI in Asia.

Outcome and survival analysis of intestinal ischaemia following cardiac surgery.

OBJECTIVES: Intestinal ischaemia is an uncommon (<1%) but serious complication of cardiac surgery with a mortality rate exceeding 50%. Diagnosis of this potentially lethal condition can be difficult and requires a high index of suspicion. The purpose of this study was to analyse the outcomes and prognostic factors in patients who develop intestinal ischaemia following cardiac surgery. METHODS: In a retrospective review from August 1999 to December 2010, we identified 31 out of 9925 (0.31%) consecutive patients who developed acute intestinal ischaemia following cardiac surgery at our tertiary centre. RESULTS: The overall mortality was 71.0%. The operative mortality was 65.4% in patients who underwent a laparotomy. Survivors of this complication had surgical intervention earlier (7.4 ± 4.9 h) compared with the non-survivors (13.9 ± 11.1 h). A total of 35 perioperative variables were analysed. A univariate analysis identified 12 variables associated with an increased risk of mortality. Logistic multivariate analysis identified the preoperative logistic EuroSCORE and the base excess at the point of diagnosis of intestinal ischaemia as significant predictors of mortality. These factors may aid prognostication in this group of patients. CONCLUSIONS: Despite the high mortality rates associated with intestinal ischaemia following cardiac surgery, early diagnosis and surgical intervention remain the only effective means to reduce mortality.

A survivor of late prosthesis migration and rotation following percutaneous transcatheter aortic valve implantation.

Transcatheter aortic valve implantation (TAVI) has emerged as a viable alternative endovascular technique in selected patients with severe aortic stenosis, who are either inoperable or at high risk for surgical aortic valve replacement. We report a case of delayed displacement and rotation of an aortic bioprosthesis, 43 days after successful TAVI via the transfemoral approach, with the patient surviving the subsequent open heart surgery required for device retrieval.