scholarly journals Performance of a Novel Bipolar/Monopolar Radiofrequency Ablation Device on the Beating Heart in an Acute Porcine Model

2013 ◽  
Vol 8 (4) ◽  
pp. 276-283 ◽  
Author(s):  
Lindsey L. Saint ◽  
Christopher P. Lawrance ◽  
Shoichi Okada ◽  
Toshinobu Kazui ◽  
Jason O. Robertson ◽  
...  
Keyword(s):  
Cardiac Output ◽  
Radiofrequency Ablation ◽  
Cross Sections ◽  
Left Atrial ◽  
Beating Heart ◽  
Tissue Thickness ◽  
Linear Lesions ◽  
Anatomic Location ◽  
The Cross ◽  
The Right

Objective Although the advent of ablation technology has simplified and shortened surgery for atrial fibrillation, only bipolar clamps have reliably been able to create transmural lesions on the beating heart. Currently, there are no devices capable of reproducibly creating the long linear lesions in the right and left atria needed to perform a Cox-Maze procedure. This study evaluated the performance of a novel suction-assisted radiofrequency device that uses both bipolar and monopolar energy to create lesions from an epicardial approach on the beating heart. Methods Six domestic pigs underwent median sternotomy. A dual bipolar/monopolar radiofrequency ablation device was used to create epicardial linear lesions on the superior and inferior vena cavae, the right and left atrial free walls, and the right and left atrial appendages. The heart was stained with 2,3,5-triphenyl-tetrazolium chloride, and each lesion was cross-sectioned at 5-mm intervals. Lesion depth and transmurality were determined. Results Transmurality was documented in 94% of all cross sections, and 68% of all ablation lines were transmural along their entire length. Tissue thickness was not different between the transmural and nontransmural cross sections (3.1 ± 1.3 and 3.4 ± 2.1, P = 0.57, respectively), nor was the anatomic location on the heart ( P = 0.45 for the distribution). Of the cross sections located at the end of the ablation line, 11% (8/75) were found to be nontransmural, whereas only 4% (8/195) of the cross sections located within the line of ablation were found to be nontransmural ( P = 0.04). Logistic regression analysis demonstrated that failure of the device to create transmural lesions was associated with low body temperature ( P = 0.006) but not with cardiac output ( P = 0.54). Conclusions This novel device was able to consistently create transmural epicardial lesions on the beating heart, regardless of anatomic location, cardiac output, or tissue thickness. The performance of this device was improved over most devices previously tested but still falls short of ideal clinical performance. Transmurality was lower at the end of the lesions, highlighting the importance of overlapping lines of ablation in the clinical setting.

scholarly journals The relationship between the arrangement of rays in secondary phloem and grain inclination in the wood of Pinus silyestris L. and Picea abies Karst

2014 ◽  
Vol 59 (1-4) ◽  
pp. 9-24
Author(s):  
Władysław Pyszyński
Keyword(s):  
Picea Abies ◽  
Cross Section ◽  
Cross Sections ◽  
Pinus Silvestris ◽  
Secondary Phloem ◽  
The Cross ◽  
Wood Grain ◽  
The Right ◽  
The Relationship ◽  
Wood Columns

The arrangement of rays in cross sections of secondary phloem and the wood grain on the tangential and radial surfaces of wood columns from <i>Pinus silvestris</i> and <i>Picea abies</i> was studied. It was found that in most cases the rays were slanted and deviated from the geometric radius in either the S-direction (to the left) or in the Z-direction (to the right) when the cross section of the stem was observed from above. The S-type deviation dominated in those stems in which the wood grain in the peripheral parts was of the S-type (left-oriented), whereas the deviation of rays in the Z-direction was found to dominate in those objects, in which the wood grain in the peripheral parts of the stem was of the Z-type (right-oriented).

scholarly journals Simultaneous Multisite Mapping of the Right and the Left Atrial Septum in the Canine Intact Beating Heart

Circulation ◽  
1999 ◽  
Vol 100 (3) ◽  
pp. 312-319 ◽  
Author(s):  
Huabin Sun ◽  
Emre O. Velipasaoglu ◽  
David E. Wu ◽  
Helen A. Kopelen ◽  
William A. Zoghbi ◽  
...  
Keyword(s):  
Left Atrial ◽  
Beating Heart ◽  
Atrial Septum ◽  
The Right

scholarly journals Strategies to Improve the Efficacy of Epicardial Linear Ablation on the Beating Heart

2016 ◽  
Vol 11 (6) ◽  
pp. 414-419 ◽  
Author(s):  
Yoshiyuki Watanabe ◽  
Matthew R. Schill ◽  
Toshinobu Kazui ◽  
Spencer J. Melby ◽  
Richard B. Schuessler ◽  
...  
Keyword(s):  
Animal Studies ◽  
Beating Heart ◽  
Triphenyltetrazolium Chloride ◽  
Surgical Ablation ◽  
Linear Lesions ◽  
Bipolar Radiofrequency ◽  
Minimally Invasive Surgical ◽  
Linear Ablation ◽  
Device Applications ◽  
The Right

Objective Creating transmural linear lesions on the beating heart is an important component of minimally invasive surgical ablation for atrial fibrillation. Animal studies have shown poor efficacy for surface bipolar radiofrequency ablation (RFA). Clinicians have developed strategies including multiple device applications and vena caval occlusion (VCO) to improve ablation efficacy. These techniques were evaluated in an acute porcine model. Methods In the first experiment, an RFA device was used to perform two 40-second epicardial ablations on the right atrium of six pigs. Ablations were performed with and without VCO. Ultrasonic flow probes were used to verify VCO. In the second experiment, an RFA device was used to perform two 40-second epicardial ablations at six locations on the left and right atria of six pigs. All animals were sacrificed. The hearts were removed and stained with 2,3,5-triphenyltetrazolium chloride. Sections were examined using digital photography. Results With VCO, 42 (81%) of 52 sections were transmural; without VCO on the RA, only 12 (24%) of 50 sections were transmural (P < 0.01). In thick (>2 mm) tissue, 10 (59%) of 17 VCO sections were transmural compared with only two (8%) of 24 with normal caval blood flow. Compared with a single ablation, multiple device applications improved transmurality on the LA but not the RA (92% vs 71%, P < 0.05). Conclusions In an acute animal model, VCO improved the efficacy of beating-heart RFA on the RA. Multiple device applications improved the efficacy of RFA on the LA.

Evaluation of an Integrated Bipolar and Unipolar Ablation Device

2014 ◽  
Vol 9 (1) ◽  
pp. 33-37 ◽  
Author(s):  
Andy C. Kiser ◽  
Hayden R. Pappas ◽  
Kelly C. Garner ◽  
Irion W. Pursell ◽  
J. Paul Mounsey ◽  
...  
Keyword(s):  
Conduction Block ◽  
Beating Heart ◽  
Porcine Heart ◽  
Linear Pattern ◽  
Linear Lesions ◽  
Bipolar Devices ◽  
Lesion Pattern ◽  
Low Profile ◽  
Ablation Pattern ◽  
The Right

Objective Bipolar lesion creation is accepted as the most effective method to create transmural atrial ablations. However, the creation of an ablation pattern on the left and the right atrium with current bipolar devices is difficult on the beating heart. We have evaluated a novel integrated ablation device that creates both bipolar and unipolar lesions in a linear pattern on the beating porcine heart. Methods Using six porcine models, we evaluated the effectiveness of creating beating heart ablation lesions by transmurality and conduction block. Isolating lesions were created on the left and right atria of the beating porcine heart. After we created sequential bipolar and unipolar lesions, we confirmed conduction block and examined the lesion depth histologically. Results Linear lesions were created successfully on the surface of the beating porcine heart. Conduction block at 20 mV was confirmed at all isolated areas, and 96.4% of the lesion sections had full thickness and were transmural at histology. Conclusions This device enables unipolar and bipolar lesion creation in a linear and low-profile manner, enabling effective creation of a biatrial lesion pattern on the epicardial surface of the beating heart.

Further evidence favoring a cardiac mechanism in irreversible hemorrhagic shock

1962 ◽  
Vol 203 (2) ◽  
pp. 248-252 ◽  
Author(s):  
Jack W. Crowell ◽  
Arthur C. Guyton
Keyword(s):  
Cardiac Output ◽  
Hemorrhagic Shock ◽  
Blood Volume ◽  
Cardiac Failure ◽  
Left Atrial ◽  
Progressive Failure ◽  
Continuous Recording ◽  
Output Curve ◽  
Early Stages ◽  
The Right

Cardiac output curves of normal dogs and dogs in various stages of hemorrhagic shock were determined with devices for continuous recording of cardiac output and atrial pressures to feed an X-Y recorder. Normal cardiac output curves were recorded during the early stages of shock but, after the animal had developed irreversible shock, a cardiac output curve indicative of cardiac failure was always recorded. As the irreversible shock progressed, successive cardiac output curves indicated progressive failure of the heart. A special feature of these experiments was that by increasing or decreasing the blood volume the cardiac output could be held constant. When the cardiac output was held constant, both the right and left atrial pressures slowly rose to extremely high values as shock progressed, and after a time the heart was unable to maintain normal output at even extremely high atrial pressures. The evidence is entirely consistent with the idea that the irreversible stage in hemorrhagic shock is caused by rapid progressive cardiac failure.

Evidence favoring a cardiac mechanism in irreversible hemorrhagic shock

1961 ◽  
Vol 201 (5) ◽  
pp. 893-896 ◽  
Author(s):  
Jack W. Crowell ◽  
Arthur C. Guyton
Keyword(s):  
Cardiac Output ◽  
Oxygen Consumption ◽  
Pulmonary Artery ◽  
Hemorrhagic Shock ◽  
Left Atrial ◽  
Peripheral Resistance ◽  
Arterial System ◽  
Operating Parameters ◽  
The Right ◽  
Oxygen Difference

Shock was induced in 55 dogs by removing blood until the arterial pressure had fallen to 30 mm Hg. The pressure was kept at this level for as long as 10 hr by constantly adding additional blood to the reservoir. The hematocrit was kept constant to prevent large variations in the viscosity. Mean pressures of the right and left atrium, the pulmonary artery, and the systemic arterial system were recorded as well as oxygen consumption and A-V oxygen difference. Total peripheral resistance and cardiac output were calculated. That period of time during which the animal passed from a reversible stage of shock to an irreversible stage of shock was studied. It was found that no significant change occurred in oxygen consumption, cardiac output, or peripheral resistance during this transition phase. However, changes did occur in the operating parameters of the heart. The left atrial pressure began rising with the transition from reversible to irreversible shock and continued rising until death of the animal. It is suggested that irreversible hemorrhagic shock is due to acute cardiac failure.

Distribution of fetal cardiac output: importance of pacemaker location

1976 ◽  
Vol 231 (1) ◽  
pp. 204-208 ◽  
Author(s):  
PT Pitlick ◽  
SE Kirkpatrick ◽  
WF Friedman
Keyword(s):  
Heart Rate ◽  
Cardiac Output ◽  
Left Atrial ◽  
Left Ventricular ◽  
Right Atrial ◽  
Atrial Pacing ◽  
Foramen Ovale ◽  
Rate Versus ◽  
Left Ventricular Output ◽  
The Right

Important questions exist about the relative roles of changes in heart rate versus extent of myocardial shortening in regulating fetal cardiac output, because increases in heart rate created by left atrial pacing have been shown to increase right ventricular output and decrease left ventricular output. Since the pacemaker site could importantly influence foramen ovale flow and, hence, each ventricle's output, changes in individual ventricular outputs were examined when both the right and left atria were paced at a rate of 270 beats/min in five acute and in eight chronically instrumented fetal lamb studies. With pacing of either atrium, total cardiac output was unchanged compared to control values. However, the right ventricle contributed more to total cardiac output with left atrial pacing (73% acute, 65% chronic) than with right atrial pacing (51% acute, 57% chronic). Converse changes were observed in left atrial pacing (27% acute, 35% chronic) as compared to right atrial pacing (49% acute, 43% chronic). Thus the disparity that exists normally in the contributions of the right and left ventricles to total cardiac output is accentuated with left atrial pacing and minimized with right atrial pacing. Pressure measurements demonstrated changes in the atrial pressure relations that would be expected to alter flow across the foramen ovale depending on the chamber initially activated. Previous experimental differences can, therefore, be attributed to changes in the magnitude of shunting across the foramen ovale and depend on pacemaker location.

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