Left Atriums Research Articles

Surgical treatment for lung cancer invading left atrium or base of pulmonary vein

Lung cancer invading left atrium or base of pulmonary vein belongs to locally advanced lung cancer (T4). The prognosis of treatment without surgery is poor. The aim of this study is to explore the feasibility and the value of surgical method in the treatment of this disease. From April, 1993 to April, 2005, lobectomy or pneumonectomy combined with extended resection of left atrium were carried out in 46 patients with locally advanced lung cancer. The operations included left low lobectomy in 20 cases, left pneumonectomy in 6 cases, right middle and low lobectomy in 12 cases, right low lobectomy in 3 cases and right pueumonectomy in 5 cases respectively. The base of the pulmonary vein was invaded by the tumor in 34 patients, while left atriums were invaded obviously in 12 patients. Two patients were operated using extracoporeal circulation because of main pulmonary artery and left atrium being invaded. The Kaplan-Meier method (Log rank test) and a COX model were used to analyse the survival and the prognosis. There was no operative mortality in this series, 15 patients had operative complication, including arrhythmia in 13 cases, pneumonia in 8 cases and heart failure in 1 case. The median survival was 35 months. The 1-, 3-, 5-year survival rates were 84.2%, 43.7%, 30.5% respectively. The survival of patients with N0/1 was better than that of patients with N2 disease, the median survival of them were 38 months and 19 months respectively (P=0.002). Using a Cox model analysis, lymph node stage (N0/1 or N2) was independent prognostic factor, while preoperative chemotherapy, sex, age and the pathologic type were not independent prognostic factors. Surgical treatment for lung cancer invading the left atrium or the base of pulmonary vein is feasible, especially for N0 patients.

SIE Method of Analysing Microwave Fields of a 3D Heart Model

The Singular Integral Equations Method (SIE) used in this article allowed us to solve Maxwell's Equations for a Three-Dimensional (3D) asymmetric heart model when a microwave catheter (MC) was placed inside the model and radiated microwaves. Here we explain the main idea of our SIE method. We first separated the solution of equations from satisfying the boundary conditions. For this purpose, we found the solution of the differential equations having a point source. This fundamental solution is used in our integral representation of a problem. The integral representation automatically satisfied the differential equations but has an unknown density function which must be found from the boundary conditions. The solution of the differential equations, obtained by our SIE method, was rigorous, that is it satisfied the differential equations and all boundary conditions. The false roots did not occur when applying our SIE method.All surfaces of the heart model were defined as a triangular mesh covering the 3Dheart surfaces. The heart model consisted of cardiac muscle and the right and left atriums with ventricles which were filled with blood. In this article we presented our calculations of the microwave electric field inside of a heart model. We have seen that our SIE method enabled one to optimal the size and shape of a MC when used to remove abnormal tissue in a heart model. We discovered that the electric field distribution most suitable for microwave ablation was a curved microwave catheter pressed against the lateral surface of heart atrium.

An Electrodynamical Analysis of a Model Heart

Presents a numerical analysis of an electrodynamical problem. The problem was solved by using our Singular Integral Equations’ Method. We formulated the problem in this way. A metal microwave catheter (antenna) was placed inside of a three dimensional asymmetric model heart. The catheter radiated a microwave with a frequency of 10 GHz. The model heart was limited by a noncoordinate shape surface. The model heart consisted of two different size cavities. The heart cavities were schematic images of the left and right atriums and ventricles. In our calculations the cavities were filled with blood and the walls of the heart consisted of myocardium tissue. In this article we analysed four model electrodynamical problems that could be used in medical microwave ablation. Several different dependences of electric field distributions were investigated at different locations and shapes of microwave catheters at two cross-sections of the heart. Our calculations showed that the electric field distribution was best suited for the ablation when we used a curved catheter that touched the inner wall of the heart. Ill. 6, bibl. 11 (in Lithuanian; summaries in Lithuanian, English, Russian).

Atrial reduction plasty Cox maze procedure: extended indications for atrial fibrillation surgery

Background The Cox maze procedure yields good results for atrial fibrillation (AF). However, patients with predictors of failure—chronic long-standing AF, low amplitude fibrillatory waves, and large left atriums—are generally thought not to benefit from a maze procedure. We report an aggressive approach for these patients, utilizing biatrial reduction plasty concomitantly with the Cox maze procedure for AF. Methods A complete Cox maze procedure utilizing supplemental RF ablation was performed in 36 patients. All underwent resection of both atrial appendages and biatrial reduction plasty encompassing resection of the left atrial posterior wall from left to right pulmonary veins and from inferior pulmonary veins to the mitral annulus, as well as removal of the right atrial lateral wall. Mitral or tricuspid valve repair, or both, was performed on 32 patients. Results These patients had a mean AF duration of 45 ± 89 months. Their preoperative left atria measured 66 ± 16 mm, with mean AF waves of 0.74 ± 0.3 mm. Mean preoperative New York Heart Association class was 2.7 ± 0.7 and left ventricular ejection fraction was 48 ± 9. Cross clamp and bypass times were 91 ± 35 minutes and 124 ± 33 minutes, respectively. The average posterior left atrial tissue resected was 5.4 × 2.1 cm, and mean resected atrial weight was 10.3 ± 2 g. There were no deaths and length of stay was 5.5 ± 2 days. At a follow-up time of 19 ± 16 months, 32 of the 36 patients were in normal sinus rhythm and New York Heart Association class I. Conclusions Aggressive biatrial reduction plasty Cox maze procedure was effective in 89% of these “low success” AF patients. This simple procedure can extend utilization of the Cox maze procedure to more patients with chronic AF.

Mechanism and incidence of notched pulmonary venous atrial reversal wave

In certain patients, pulmonary venous flow pattern obtained by the pulsed wave Doppler during transesophageal echocardiography shows a notching on the atrial reversal (A) wave. However, the incidence or the mechanism of this notched A wave has not been described. After transthoracic echocardiographic evaluation for the chamber sizes, wall thickness, and left-ventricular function, transesophageal echocardiography was performed in 100 patients with in sinus rhythm. Discernible pulmonary venous A wave was observed in 46 patients. Among these 46 patients, notched A wave was observed in 11 (31%). In 4 patients with notched A wave, left-atrial pressure waveforms could be obtained during mitral balloon valvuloplasty. In all these patients, left-atrial pressure waveforms showed prominent c waves. In 2 patients, transesophageal echocardiography was repeated after mitral balloon valvuloplasty. Late peak of the notched A wave decreased with the decrease in the magnitude of rise in left-atrial c wave. Among the transthoracic echocardiographic parameters, patients with notching (n = 11) had significantly larger left atriums than patients without notching (n = 35)(49.3 ± 6.2 vs 37.3 ± 4.4 mm, P <.0001). There were no significant differences in left-ventricular dimensions, wall thickness, and ejection fraction. In conclusion, notched pulmonary venous A wave indicates the presence of left-atrial c wave; and presence of left-atrial c wave may represent decreased left-atrial compliance. (J Am Soc Echocardiogr 2003;16:77-9.)

Gross structure of the atriums: more than an anatomic curiosity?

Despite the extensive literature concerning atrial arrhythmias, there are relatively few articles on the anatomy of the atrial chambers. Since electrophysiological mapping and interventional treatments of atrial arrhythmias involve entering the chambers, this article reviews the gross structures to provide a better understanding of the atriums, the septum, and the connecting great veins. In addition, based on the human heart, differences between porcine and canine hearts are highlighted. The right and left atriums are characterized by morphologically distinct appendages. The right atrium contains prominent muscular bundles and an extensive array of pectinate muscles. The distal ramifications of the terminal crest lead to the "flutter" isthmus. By contrast, the left atrium has relatively smooth walls. The atrial septum is limited to the valve of the oval fossa and its immediate muscular rim. Atrial musculature extends beyond the veno-atrial junctions to the outside of the pulmonary veins. The longest sleeves are around the upper pulmonary veins, and similar sleeves are seen around the superior caval vein. The structure of the atrium is more than an anatomic curiosity. It has practical implicationsfor mapping and interventional procedures.

The anatomy of interatrial communications--what does the interventionist need to know?

Increasingly, the interventional cardiologist is seeking to close interatrial communications by inserting devices by means of catheterisation. So as to optimise these procedures, it is advantageous to have a firm grasp of the anatomy of the normal atrial septal structures, this then providing the basis to understand the morphology of the holes which can exist between the chambers, not all of which are true septal defects. A true septal structure can be removed without exiting from the cavities of the heart. It is the flap valve of the oval fossa, along with the anterior rim of the fossa, which fulfill this criterion. The remainder of the extensive rim of the normal fossa is no more than an infolding between the walls of the right and left atria and their venous tributaries, and has different dimensions at various points around the circumference. The so-called muscular atrioventricular "septum" is a sandwich incorporating a layer of epicardial fibro-adipose tissue. True defects of the atrial septum, therefore, exist because of deficiency, perforation, or absence of the flap valve. Most of these defects will prove suitable for interventional closure, but potential caveats include multiple defects, aneurysm of the flap valve, or adjacency of the fossa to the venous orifices. The other interatrial communications, namely the sinus venosus, coronary sinus, and "ostium primum" defects are outside the confines of the oval fossa. Recognition of this feature is the key to their diagnosis, and their differentiation from true atrial septal defects. Of these defects, only the coronary sinus defect is likely to be suitable for device closure, and then only in the very rare circumstances when it is seen in isolation.

Contrast echoes detected during percutaneous mitral balloon commissurotomy with Inoue balloons and their relation to cerebral microembolic signals.

The aim of this study was to find out the mechanism of genesis of contrast echoes detected with echocardiography during percutaneous mitral balloon commissurotomy (PMBC) procedures with Inoue balloons and to assess their association with cerebral microembolic signals with transcranial Doppler examinations. Ten Inoue balloons (Toray Instruments) were used in 10 patients (mean age 36 +/- 10 years). In all patients transesophageal echocardiographies with a multiplane 5 MHz probe were performed immediately before and during the PMBC procedure. None of the patients had left atrial thrombus during the PMBC. All of the balloons were inflated within the left atriums and left ventricles and were tested in saline to see whether there was a visible air leak after the PMBC procedures. Transcranial Doppler examinations were done with 2 MHz probes from the middle cerebral artery. Contrast echoes were detected in all patients during inflation and/or deflation, independent of the intracardiac sites. After a few cardiac cycles there was a very intense shower of microembolic signals detected with the transcranial Doppler examination, which persisted for all inflations and/or deflations. All balloons yielded visible air leaks from the two small holes at the waist of the balloons in saline. There were a few contrast echoes recorded in some of the patients during the exchange of equipment, and one patient had a transient neurologic and coronary ischemic event following the introduction of the stretcher tube of the Inoue balloon. Intracardiac contrast echoes and transcranial microembolic signals during the PMBC procedure were detected in all PMBC procedures and were due to air that was entrapped between the two latex layers of the Inoue balloons and air introduced from outside during the exchange of the equipment.

Nonlinear mathematical analysis of the hemodynamic parameters during left ventricular assistance with oscillated blood flow.

For the development of a totally implantable ventricular assist system (VAS), we have been developing the vibrating flow pump (VFP), which can generate oscillated blood flow with a relatively high frequency (10-50 Hz) for a totally implantable system. In this study, effects of left ventricular assistance with this unique oscillated blood flow were analyzed by nonlinear mathematics for evaluation as the entire circulatory regulatory system, not as a separate part of the system. Left heart bypasses using VFPs from the left atriums to the descending aortas were performed in chronic animal experiments using healthy adult goats. Electrocardiogram (ECG), arterial blood pressure, VFP pump flow, and flow of the descending aorta data taken while the goats were awake were recorded in the data recorder and analyzed in the personal computer system through the AD convertor. Using nonlinear mathematics, time series data were embedded into the phase space, and the Lyapunov numerical method, fractal dimension analysis, and power spectrum analysis were performed to evaluate the nonlinear dynamics. During left ventricular assistance with the VFP, Mayer wave fluctuations were decreased in the power spectrum, the fractal dimension of the hemodynamics was significantly decreased, and peripheral vascular resistance was significantly decreased. These results suggest that nonlinear dynamics, which mediate the cardiovascular dynamics, may be affected during LV bypass with oscillated flow. Decreased power of the Mayer wave in the spectrum caused the limit cycle attractor of the hemodynamics and decreased the peripheral resistance. Decreased sympathetic discharges may be the origin of the decreased Mayer wave and fractal dimension. These nonlinear dynamical analyses may be useful to design the optimal VAS control.

Segmental Pulmonary Angiography in the Critically-Ill Patient Using a Flow-Directed Catheter

Selective pulmonary angiography was performed using a flow-directed, balloon-tipped catheter in 20 consecutive intensive care unit patients requiring heart catheterizations on the right side for hemodynamic monitoring. No morbidity was encountered from this procedure. Adequate quality balloon-occlusion angiographs were obtained with a portable chest roentgenogram in 17 (85 percent) but appeared normal in only 12 (60 percent), seriously limiting the usefulness of this technique in the diagnosis of occult pulmonary embolisms. With this technique, the catheter tip was found to be in a segmental pulmonary artery anterior to the left atrium (zone I) in 30 percent of the patients. From these findings, we conclude that not infrequently the catheter tip was situated in zone I anterior to the left atriums. Slective pulmonary angiography using a flow-directed, balloon-tipped catheter proved useful in demonstrating the precise location of the catheter tip. When this is the case, the catheter tip should be relocated to a segment below the left atrium (zone III) in patients requiring positive end-expiratory pressure because the "wedge" pressure measured in zone I may not accurately reflect left atrial pressure.

犬心房内刺戟伝導系の組織学的研究(第2報) : 靜脈洞結節-右房系及び靜脈洞結節-左房系の刺戟伝導特殊筋系に就て

In preceding report I, the sinus node and the Tawara node were investigated histologically. This report was on the examination of the specific conducting systems to the right and left atriums from the sinus node. The materials and methods were the same as those stated in report I.Results : The findings are summarized as follows.1) The specific muscular fibers in the atrial portion are not so prominent as the sinus node, the Tawara node and Purkinje's fibers in the ventricle.2) The main pathways of the atrial portion are as follow.A) A pathway, arising from the projection of the head of the sinus node, surrounding the base of the V. cava superior.B) One of the projection of the head of the sinus node is distributed in the right atrial appendage.C) The pathway arising from the head of the sinus node along the intermediate right atrial artery near the junction of the right appendage with the right atrial body.D) The pathway arising from the tail of the sinus node along the Arteriola sini (dorsal right atrial artery) near the junction of the V. cava inferior with the right atrial body.E) In addition, the further fine branches from the above chief pathways are distributed in the anterior and posterior bodies of the right atrium.F) The above mentioned pathways are more prominent near the sinus node, not so peripherally.3) The main pathways in the left atrium : This system is found as fine muscular bundles consisting of a few muscular fibers, arising from the projections of the head of the sinus node, passing over the cava venous appendage's angle and going to the left side of the atrial septum along the Bachmann's bundle in the subendocardium and subepicardium of the right atrial wall of the aortic side. Further, the system is extended to the left atrium and distributed in the left atrial appendage and around the pulmonary veins.