Evaluation of mitral chordae tendineae length using four-dimensional computed tomography.

BACKGROUND: Mitral valvuloplasty using artificial chordae tendineae represents an effective surgical approach for treating mitral regurgitation. Achieving precise measurements of artificial chordae tendineae length (CL) is an important factor in the procedure; however, no objective index currently exists to facilitate this measurement. Therefore, preoperative assessment of CL is critical for surgical planning and support. Four-dimensional x-ray micro-computed tomography (4D-CT) may be useful for accurate CL measurement considering that it allows for dynamic three-dimensional (3D) evaluation compared to that with transthoracic echocardiography, a conventional inspection method. AIM: To investigate the behavior and length of mitral chordae tendineae during systole using 4D-CT. METHODS: Eleven adults aged > 70 years without mitral valve disease were evaluated. A 64-slice CT scanner was used to capture 20 phases in the cardiac cycle in electrocardiographic synchronization. The length of the primary chordae tendineae was measured from early systole to early diastole using the 3D image. The primary chordae tendineae originating from the anterior papillary muscle and attached to the A1-2 region and those from the posterior papillary muscle and attached to the A2-3 region were designated as cA and cP, respectively. The behavior and maximum lengths [cA (ma), cP (max)] were compared, and the correlation with body surface area (BSA) was evaluated. RESULTS: In all cases, the mitral anterior leaflet chordae tendineae could be measured. In most cases, the cA and cP chordae tendineae could be measured visually. The mean cA (max) and cP (max) were 20.2 mm ± 1.95 mm and 23.5 mm ± 4.06 mm, respectively. cP (max) was significantly longer. The correlation coefficients (r) with BSA were 0.60 and 0.78 for cA (max) and cP (max), respectively. Both cA and cP exhibited constant variation in CL during systole, with a maximum 1.16-fold increase in cA and a 1.23-fold increase in cP from early to mid-systole. For cP, CL reached a plateau at 15% and remained elongated until end-systole, whereas for cA, after peaking at 15%, CL shortened slightly and then moved toward its peak again as end-systole approached. CONCLUSION: The study suggests that 4D-CT is a valuable tool for accurate measurement of both the length and behavior of chordae tendineae within the anterior leaflet of the mitral valve.

Novel visualised three-dimensional images are useful for treating coronary artery fistulas in infants.

Here we report an infant with coronary artery fistulas. To clearly visualise the fistulas and surrounding materials, we utilised three-dimensional computed tomography, and the images were transferred as novel visualised three-dimensional images using a reconstruction technique. With the images, we could repair the fistulas accurately. We believe that these images are useful for repairing coronary artery fistulas in infants.

[Left atrial giant myxoma incidentally discovered during endoscopic ultrasonography; report of a case].

A 49-year-old female patient with a symptom of dysphagia underwent endoscopic ultrasonography (EUS) of the upper gastrointestinal tract, which incidentally revealed a tumor compressing the esophagus from outside. Transthoracic echocardiography performed after EUS showed a giant tumor in the left atrium. The tumor, measuring 75×68×43 mm, weighing 105 g was successfully removed, and pathologically diagnosed as myxoma. Her symptom disappeared completely. When performing clinical studies, it is important to pay every attention not to miss any abnormal findings beyond the scope of targeted areas. We also mentioned an ambiguity of the term," giant" regarding the size and weight of myxoma.

Safety advantage of modified minimally invasive cardiac surgery for pediatric patients.

Minimally invasive cardiac surgery (MICS) using a small surgical incision in children provides less physical stress. However, concern about safety due to the small surgical field has been noted. Recently, the authors developed a modified MICS procedure to extend the surgical field. This report assesses the safety and benefit of this modified procedure by comparing three procedures: the modified MICS (group A), conventional MICS (group B), and traditional open heart surgery (group C). A retrospective analysis was performed with 111 pediatric patients (age, 0-9 years; weight, 5-30 kg) who underwent cardiac surgery for simple cardiac anomaly during the period 1996-2010 at Juntendo University Hospital. The modified MICS method to extend the surgical view has been performed since 2004. A skin incision within 5 cm was made below the nipple line, and the surgical field was easily moved by pulling up or down using a suture or a hemostat. The results showed no differences in terms of gender, age, weight, or aortic cross-clamp time among the groups. Analysis of variance (ANOVA) indicated significant differences in mean time before cardiopulmonary bypass (CPB), CPB time, operation time, and bleeding. According to the indices, modified MICS was similar to traditional open surgery and shorter time or lower bleeding volume than conventional MICS. No major mortality or morbidity occurred. In conclusion, the modified MICS procedure, which requires no special techniques, was as safe as conventional open heart surgery and even reduced perioperative morbidity.

Endoclamp balloon visualization and automatic placement system.

OBJECTIVES: Aortic occlusion is one of the most important open discussions in minimally invasive cardiac surgery. Different techniques can be employed, and all have benefits and drawbacks. The objective of our work is to improve the safety of internal aortic occlusion with the Port Access technique, which employs an endoclamp balloon catheter. We propose a combined information and positioning system based on augmented reality technology and robotics in which the position of the balloon can be seen at all times and can be automatically controlled by a robotic actuator. METHODS: The system was designed by a multidisciplinary team of engineers, medical doctors, and human factor specialists in a human-centered design approach. We measure the balloon position in real time with a magnetic tracking system. This position is superimposed on a 3-dimensional scan of the patient's thorax, with the balloon in the artery shown at all times. The position measurement is also used to control the robotic catheter inserter that places and maintains the balloon position at a specified target. The system was evaluated in 2 user studies that compared it with other visual aids. RESULTS: The user tests have shown that the system effectively supports the surgeon in the placement task, with an increase in placement accuracy and a reduction in time compared with the current visualization technique. The users also rated the system as supporting them well. CONCLUSIONS: The clinical feasibility of the system was proved. The system provides better visualization and position control and can effectively increase the safety of the procedure. This system has the potential of making Port Access a more attractive technique.

Starling-effect-independent lusitropism index in canine left ventricle: logistic time constant.

The logistic time constant (tau(L)) has been proposed as a better index of the rate of left ventricular (LV) relaxation or lusitropism than the conventional monoexponential time constant (tau(E)). However, whether and how the Frank-Starling effect influences tau(L) remains to be elucidated. We compared the effect of LV volume (LVV) loading on both logistic and monoexponential fittings. The isovolumic LV relaxation pressure curves from the maximum negative time derivative of pressure (-dP/dt(max)) were analyzed at 3 different end-points at 4 LVVs of 10, 12, 14, and 16 mL in 8 excised, cross-circulated canine hearts. We found that the logistic fitting was superior to the monoexponential fitting at all LVVs and end-points. LVV loading did not affect tau(L) but affected tau(E) slightly. Although the advancing end-point increased both tau(L) and tau(E), the increases were significantly smaller for tau(L) than for tau(E) at all LVVs. Moreover, the changes in both the amplitude constants and nonzero asymptotes with the advancing end-point were significantly smaller for the logistic fitting than for the monoexponential fitting. We conclude that tau(L) served as a more reliable index of lusitropism that is independent of the change in LVV loading or the Frank-Starling effect.

Predictability of O2 consumption from contractility and mechanical energy of absolute arrhythmic beats in canine heart.

Left ventricular (LV) O2 consumption (V(O2)) per minute is measurable for both regular and arrhythmic beats. LV V(O2) per beat can then be obtained as V(O2) per minute minute divided by heart rate per minute minute for regular beats, but not for arrhythmic beats. We have established that V(O2) of a regular stable beat is predictable by V(O2) = a PVA + b E(max) + c, where PVA is the systolic pressure-volume area as a measure of the total mechanical energy of an individual contraction and E(max) is the end-systolic maximum elastance as an index of ventricular contractility of the contraction. Furthermore, a is the O2 cost of PVA, b is the O2 cost of E(max), and c is the basal metabolic V(O2) per beat. We considered it theoretically reasonable to expect that the same formula could also predict LV V(O2) of individual arrhythmic beats from their respective PVA and E(max) with the same a, b, and c. We therefore applied this formula to the PVA - Emax data of individual arrhythmic beats under electrically induced atrial fibrillation (AF) in six canine in situ hearts. We found that the predicted V(O2) of individual arrhythmic beats highly correlated linearly with either their V(O2) (r = 0.96 +/- 0.01) or E(max) (0.97 +/- 0.03) while both also highly correlated linearly with each other (0.88 +/- 0.04). This suggests that the above formula may be used to predict LV Vo2 of absolute arrhythmic beats from their Emax and PVA under AF.

Normal distribution of ventricular pressure-volume area of arrhythmic beats under atrial fibrillation in canine heart.

We previously found the frequency distribution of the left ventricular (LV) effective afterload elastance (E(a)) of arrhythmic beats to be nonnormal or non-Gaussian in contrast to the normal distribution of the LV end-systolic elastance (E(max)) in canine in situ LVs during electrically induced atrial fibrillation (AF). These two mechanical variables determine the total mechanical energy [systolic pressure-volume area (PVA)] generated by LV contraction when the LV end-diastolic volume is given on a per-beat basis. PVA and E(max) are the two key determinants of the LV O(2) consumption per beat. In the present study, we analyzed the frequency distribution of PVA during AF by its chi(2), significance level, skewness, and kurtosis and compared them with those of other major cardiodynamic variables including E(a) and E(max). We assumed the volume intercept (V(0)) of the end-systolic pressure-volume relation needed for E(max) determination to be stable during arrhythmia. We found that PVA distributed much more normally than E(a) and slightly more so than E(max) during AF. We compared the chi(2), significance level, skewness, and kurtosis of all the complex terms of the PVA formula. We found that the complexity of the PVA formula attenuated the effect of the considerably nonnormal distribution of E(a) on the distribution of PVA along the central limit theorem. We conclude that mean (SD) of PVA can reliably characterize the distribution of PVA of arrhythmic beats during AF, at least in canine hearts.

[Fast-track cardiac anesthesia and perioperative management appropriate for early rehabilitation after coronary artery bypass graft (CABG) surgery].

BACKGROUND: Rapid mobilization and rehabilitation after CABG has a potential benefit of reducing both costs and pulmonary complications (such as atelectasis and pulmonary embolism). Moreover, it improves the patient's emotional recovery. We performed fast-track cardiac anesthesia aiming toward early rehabilitation. METHODS: Patients undergoing CABG surgery (total, 140: on-pump 97, off-pump 43) were studied. Anesthesia was induced and maintained with low doses of fentanyl and propofol. The outcome of our perioperative management was retrospectively reviewed on the basis of clinical records. RESULTS: The duration of the operation was 282 +/- 71 min. Anesthesia time was 353 +/- 72 min. The doses of fentanyl and propofol were 11.9 +/- 2.9 microg x kg(-1) and 16.8 +/- 5.4 mg x kg(-1), respectively. Time to extubation was 213 +/- 676 min, and the percentage of cases extubated within 3 h was 82%. As for outcome, the percentages of first oral intake, first rising from bed, and first gait performed on postoperative day 1 were 92%, 78%, 61%, respectively. The period of ICU stay was 2 days (median value). There were no perioperative complications related to early rehabilitation. CONCLUSIONS: We can safely manage fast-track cardiac anesthesia and perioperative management aiming toward early rehabilitation after CABG surgery.

Frequency distribution, variance, and moving average of left ventricular rhythm and contractility during atrial fibrillation in dog.

Mean levels of left ventricular rhythm and contractility averaged over arrhythmic beats would characterize the average cardiac performance during atrial fibrillation (AF). However, no consensus exists on the minimal number of beats for their reliable mean values. We analyzed their basic statistics to find out such a minimal beat number in canine hearts. We produced AF by electrically stimulating the atrium and measured left ventricular arrhythmic beat interval (RR) and peak isovolumic pressure (LVP). From these, we calculated instantaneous heart rate (HR = 60,000/RR), contractility (E(max) = LVP/isovolumic volume above unstressed volume), and beat interval ratio (RR1/RR2). We found that all their frequency distributions during AF were variably nonnormal with skewness and kurtosis. Their means +/- standard deviations alone cannot represent their nonnormal distributions. A 90% reduction of variances of E(max) and RR1/RR2 required a moving average of 15 and 24, respectively, arrhythmic beats on the average, whereas that of RR and HR required 60 beats on the average. These results indicate that a statistical characterization of arrhythmic cardiodynamic variables facilitates better understanding of cardiac performance during AF.