Coronary sinus venoarterial CO2 difference in different hemodynamic states

Myocardial metabolic rate and coronary flow are closely related limiting thus the diagnostic value of coronary sinus saturation monitoring as an indicator of flow. Regional venoarterial CO2 gradient was found elevated during low flow in various clinical and experimental conditions, in animals and humans. This study was undertaken to examine the impact of the variations of cardiac mechanical work on veno-arterial CO2 content and partial pressure difference (deltaPCO2) of the coronary sinus blood. Twenty-seven patients of either sex (m/f = 21/6), undergoing coronary artery bypass grafting under extracorporeal circulation, were studied. Monitoring included a Swan-Ganz catheter and a coronary sinus line. The correct position of the late was verified by the waveform displayed in the monitor. Immediately after cannulae placement, a hemodynamic profile was obtained and simultaneous arterial and coronary sinus sampling for blood gas analysis was done in an ABL 720 (Radiometer Copenhagen) analyzer. A second collection of the same data was obtained five minutes later with the patients in a slight "head-down" position. Conditions for exclusion was intersample variation of hemoglobin's concentration greater than 15% and sodium ion concentration difference greater than 10% of the greater value. Arteriovenous oxygen partial pressure difference (deltaP(a-cs)O2), veno-arterial carbon dioxide partial pressure difference (deltaP(cs-a)CO2), O2 & CO2 content difference and heart's respiratory quotient were calculated and correlated to cardiac output (CO) and the other hemodynamic parameters. Statistical analysis employed t-paired test and linear regression. No ischemia was detected during sampling. "Head-down" position had a significant impact to all hemodynamic parameters except heart rate. In both data rows, although CO ranged widely and altered significantly, coronary sinus oxygen saturation and arteriovenous O2 content difference were stable and showed insignificant correlations to all the hemodynamic parameters that were studied. Carbon dioxide content difference (coronary sinus-arterial) showed a trending of decrease with higher flow. DeltaP(cs-a)CO2 appeared stable and independent of flow. Finally, respiratory quotient decreased significantly from 0.91 +/- 0.4 to 0.86 +/- 0.4 (mean +/- SD; p < 0.05). The heart's high basal oxygen consumption and the almost near hemoglobin's desaturation transcoronary extraction of oxygen limits the value of coronary sinus saturation monitoring as indicator of coronary flow. Heart's little extraction reserve is faced with coronary flow reserve. In the physiologic range and under the conditions of anesthesia, elevated CO2 production is accompanied with increased coronary flow. Under these circumstances, deltaP(cs-a)CO2 appears stable and is not suitable for clinical decisions concerning heart's coronary flow.     

Lymphovascular space involvement is the sole independent predictor of lymph node metastasis in clinical early stage endometrial cancer

Purpose

To determine clinicopathological risk factors associated with lymph node metastasis in endometrial cancer (EC).

Methods

Clinicopathological data of patients who underwent comprehensive surgical staging for clinical early stage EC between 2001 and 2010 at Hacettepe University Hospital was retrospectively reviewed.

Results

Two hundred and sixty-one patients were included. There were 26 patients (10.0 %) with lymph node metastasis. Of these, 14 (5.4 %) had pelvic lymph node metastasis, 8 (3.1 %) had both pelvic and paraaortic lymph node metastasis, and 4 (1.5 %) had isolated paraaortic metastasis. Univariate analysis revealed tumor size >2 cm, type II cancer, grade III histology, cervical stromal invasion, deep myometrial invasion, positive peritoneal cytology, adnexal involvement, serosal involvement, and presence of lymphovascular space involvement (LVSI) as significant clinicopathological factors associated with retroperitoneal lymph node metastasis. For paraaortic metastasis either isolated or with pelvic lymph node metastasis, significant factors were grade III disease, cervical stromal invasion, deep myometrial invasion, positive peritoneal cytology, adnexal involvement, serosal involvement, pelvic lymph node metastasis, and presence of LVSI. The only factor associated with isolated paraaortic lymph node metastasis was LVSI. Multivariate analysis revealed LVSI as the only independent factor for both retroperitoneal and paraaortic lymph node metastasis (odds ratio 14.9; 95 % confidence interval 3.8–59.0; p < 0.001, and odds ratio 20.9; 95 % confidence interval 1.9–69.9; p = 0.013, respectively).

Conclusion

Lymphovascular space involvement is the sole predictor of lymph node metastasis in EC. Therefore, LVSI status should be requested from the pathologist during frozen examination whenever possible to consider when a decision to perform or omit lymphadenectomy is made.     

Single-channel pharmacology of mibefradil in human native T-type and recombinant Ca(v)3.2 calcium channels

To study the molecular pharmacology of low-voltage-activated calcium channels in biophysical detail, human medullary thyroid carcinoma (hMTC) cells were investigated using the single-channel technique. These cells had been reported to express T-type whole-cell currents and a Ca(v)3.2 (or alpha 1H) channel subunit. We observed two types of single-channel activity that were easily distinguished based on single-channel conductance, voltage dependence of activation, time course of inactivation, rapid gating kinetics, and the response to the calcium agonist (S)-Bay K 8644. Type II channels had biophysical properties (activation, inactivation, conductance) typical for high-voltage-activated calcium channels. They were markedly stimulated by 1 microM (S)-Bay K 8644, allowing to identify them as L-type channels. The channel termed type I is a low-voltage-activated, small-conductance (7.2 pS) channel that inactivates rapidly and is not modulated by (S)-Bay K 8644. Type I channels are therefore classified as T-type channels. They were strongly inhibited by 10 microM mibefradil. Mibefradil block was caused by changes in two gating parameters: a pronounced reduction in fraction of active sweeps and a slight shortening of the open-state duration. Single recombinant low-voltage-activated T-type calcium channels were studied in comparison, using human embryonic kidney 293 cells overexpressing the pore-forming Ca(v)3.2 subunit. Along all criteria examined (mechanisms of block, extent of block), recombinant Ca(v)3.2 interact with mibefradil in the same way as their native counterparts expressed in hMTC cells. In conclusion, the pharmacologic phenotype of these native human T-type channels--as probed by mibefradil--is similar to recombinant human Ca(v)3.2.