Learning curve predictors for minimally invasive mitral valve surgery; how far should the rabbit hole go?

OBJECTIVE: To analyze predictors that influence the learning curve of minimally invasive mitral valve surgery (MIMVS). METHODS: Patients who underwent MIMVS between March 2010 to March 2015 were retrospectively analyzed. Predictive factors that influence the learning curve were analyzed. RESULTS: One hundred and five patients were included in the analysis. Cardiopulmonary bypass (CPB) time in minutes was 158.72 ± 40.98 and the aortic cross-clamp (ACC) time in minutes was 114.48 ± 27.29. There were three operative mortalities, one stroke and five >2+ mitral regurgitation. ACC time in minutes was higher in the low logistic Euroscore II (LES) group (LES < 5% = 118.42 ± 27.94) versus (LES ≥ 5 = 88.66 ± 22.26), P < .05 while creatinine clearance in µmol/L was higher in the LES < 5% group (LES < 5% = 84.32 ± 33.7) versus (LES ≥ 5% = 41.66 ± 17.14), (P < .05). One patient from each group required chest tube insertion for pleural effusion P < .05. The cumulative sum analysis (CUSUM) for the first 25 patients had CPB and ACC times that reached the upper limits. Between 25 to 64 patients the curve remained stable while with the introduction of reoperations and complex surgical procedures the CUSUM reached the upper limits. CONCLUSIONS: The learning curve is affected by many factors but this should not desist surgeons from approaching this technique. The introduction of high-risk patients in clinical practice should be carefully measured based on surgeon experience.

Does cryomaze injure the circumflex artery?: a preliminary search for occult postprocedure stenoses.

OBJECTIVE: Ensuring the transmurality of the mitral isthmus lesion, a critical component of the cryomaze, entails mirror-image application of the cryoprobe both on endocardial and epicardial surfaces when carrying out ablation. Concerns of circumflex artery injury have been expressed during the epicardial application of the cryoprobe over the coronary sinus as the artery courses on the posterior surface of the sinus in the atrioventricular (AV) groove. The objective of this study was to analyze the incidence of significant injury to the circumflex artery and its impact on outcomes, if any, in those patients who have undergone cryomaze. METHODS: Between August 2004 and December 2009, a total of 223 patients underwent argon-based cryoablation (120-second application at -140°C). After Western Institutional Review Board approval, 20 consecutive patients with normal results of preoperative coronary angiograms (right dominance, 75%; left dominance, 15%; codominant circulation, 10%) and who were at least 6 months postablation were enrolled in this study. The mean ± SD age was 60.74 ± 14.99 years, 35% were men, and 50% belonged to New York Heart Association class III/IV. The mean ± SD atrial fibrillation duration was 23.83 ± 36.28 months (65% were paroxysmal). Ten percent (n = 2) underwent primary cryomaze, 40% (n = 8) underwent cryomaze plus mitral valve repair, and 50% (n = 10) underwent two or more concomitant valvular procedures. Twelve patients underwent biatrial cryomaze, and eight underwent only left-sided cryomaze. All patients underwent a 24-hour Holter monitoring, electrocardiogram stress test, and a coronary computed tomographic angiogram, as per the protocol of this study. RESULTS: At discharge, 85% had normal sinus rhythm, whereas 15% of the patients were paced. On a mean ± SD follow-up at 32.57 ± 19.51 months, the Holter and/or pacemaker interrogation revealed AV synchrony in all patients-16 in sinus rhythm and 4 with heart block who converted to AV synchrony after subsequent pacemaker implantation. The stress test was available for 18 patients, and its results were negative in all of them. On the computed tomographic angiogram, 95% of the patients had a completely patent circumflex artery. Stenosis was noticed in only one patient (right dominant circulation), with a 30% to 40% tubular stenosis of the circumflex artery. However, this lesion corresponded to the P1 area of the mitral annulus and was significantly proximal on the circumflex to the P3 area, where the cryoprobe was applied during the cryomaze procedure. CONCLUSIONS: Barring one case of partial circumflex stenosis, likely due to the ongoing normal progression of coronary artery disease, these data derived from a limited prospective trial suggest that epicardial application during the cryomaze procedure does not cause anatomic or physiological compromise of the circumflex artery. Nevertheless, laboratory and anecdotal evidence exist that conflict with this conclusion, and caution should be exercised when applying cryothermy in the vicinity of coronary arteries.

Anthropometric correlates of blood pressure in normotensive Pakistani subjects.

Obesity and hypertension are two major inter-related cardiovascular risk factors. Decrease in adiposity is one of the most effective preventive measures not only in decreasing the overall cardiovascular risk but also the blood pressure. This cross-sectional study measured the effect of various measures of adiposity on blood pressure in normal healthy subjects of Pakistani origin. 400 normotensive subjects (247 males and 153 females) were included in this study. Along with data on co-morbid conditions, two blood pressure readings and several anthropometric measurements were recorded. Age and gender specific analysis was done. Following the WHO cutoffs for Asians, about 52% of our sample population was found to be overweight or obese. Age was not associated with blood pressure indices in males; however it was strongly associated with all blood pressure indices in females. Greater Body Mass Index (BMI), Waist Circumference (WC) and Waist to Height Ratio (WHTR) were associated with higher Systolic and Diastolic Blood pressure. Increasing age was also associated with higher levels of BMI, WC and WHTR. Anthropometric variables however, were more strongly associated with blood pressure indices than age in this sample population. In conclusion, we found WC and WHTR to be strongly associated with blood pressure indices in normotensive Pakistani males.