H. Tevaearai - Academia.edu (original) (raw)
Papers by H. Tevaearai
Minimally invasive cardiac surgery requires a learning period before the advantages of the method... more Minimally invasive cardiac surgery requires a learning period before the advantages of the method can be demonstrated. We report the progress of our results over 21 consecutive months. 27 patients were considered for minimally invasive coronary bypass via a small thoracotomy. We compare the results of four consecutive groups corresponding to an initial period (July-December 1997; n = 7; 66.8 +/- 8.9 years), an intermediate period (January-June 1998; n = 4; 48.1 +/- 11.2 years), an advanced period (July-December 1998; n = 7; 62.9 +/- 7.0 years) and a current period (January-March 1999; n = 7; 59.3 +/- 10.9 years). 2 patients were converted to sternotomy during the first year of experience. The operating time was reduced from 124 +/- 14 min and 118 +/- 20 min during the initial and intermediate periods to 99 +/- 18 and 98 +/- 18 min during the last two periods. The ICU stay was 2.6 +/- 1.1 days during the initial period and diminished respectively to 1.5 +/- 0.6, 1.7 +/- 0.8 and 1.6 +/- 0.5 days during the intermediate, advanced and current periods. The postoperative hospital stay was reduced from 9.0 +/- 1.4 days to 6.3 +/- 4.6, 5.2 +/- 1.7 and 5.9 +/- 1.5 days respectively. The benefits of minimally invasive coronary bypass were estimated by comparing the results of the last two periods with those of patients operated on through a sternotomy, on a beating heart (n = 12; 62.6 +/- 8.2) or under CPB (n = 81; 63.0 +/- 8.5). In these situations, operative time was 144 +/- 41 min and 180 +/- 35 min respectively. The ICU stay was 1.5 +/- 0.6 and 2.2 +/- 0.9 days, and the postoperative hospital stay was 7.5 +/- 2.8 and 8.6 +/- 3.0 days. We conclude that a learning period is necessary before the real benefits of the minimally invasive approach to coronary disease can be demonstrated. This method will soon replace traditional sternotomy in certain indications
ASAIO Journal, 2001
The efficiency of left ventricular assist devices (LVADs) depends on the capacity of the inflow c... more The efficiency of left ventricular assist devices (LVADs) depends on the capacity of the inflow cannula to drain blood into the pump. Left atrial (LA) and left ventricular (LV) sites were compared in an animal model mimicking different hemodynamic conditions. Three calves (56.3+/-5.0 kg) were equipped with a Thoratec LVAD. A regular cardiopulmonary bypass (CPB) circuit was used as a right ventricular assist device (RVAD) (jugular vein/pulmonary artery), and preload conditions were adjusted by storage (or perfusion) of blood into (or from) the venous reservoir. LA and LV drainage, tested separately or simultaneously, was measured by its effect on the LVAD's performance. The LVAD was used alone on a beating heart or together with the RVAD (biVAD) on a beating and on a fibrillating heart. Increasing the central venous pressure (CVP) highlighted the differences between the LA and LV cannulation sites when the LVAD was tested either alone or together with the RVAD (biVAD) on a beating heart. Drainage through the LA or the LV was similar when CVP was set at 8 mm Hg, and increasing CVP to 14 mm Hg allowed for better drainage through the LV cannula. In contrast, after induction of fibrillation to mimic extreme heart failure, the drainage was better through the LA cannula. Using both LA and LV cannulae simultaneously did not improve the LVAD output in any of the conditions tested. LV cannulation provides better blood drainage when used on a normal beating heart and, therefore, allows for increased LVAD performance. However, in severe heart failure, blood drainage through the LV cannula decreases and the LA cannulation site is superior.
ASAIO Journal, 2001
LwEBMENT CF R I m VENIRICULAR m s T m c E (mm) mNGmPuMPc4EiG 'lbmaintain stablehen-@mamicsdning d... more LwEBMENT CF R I m VENIRICULAR m s T m c E (mm) mNGmPuMPc4EiG 'lbmaintain stablehen-@mamicsdning dfpumpC4BGA right ventricular assist &vice named Heart C M was c k v e l~p u r p o S e ; In this stu&,pump pa-famances were waluated in vitro and in viva Mataials and MeQ-c9B was canpcsed d blccd pump(ciaphragm type, strdce vdumeBml) andcannula(cuter ciam Umm,Iength Ban). At the tip d the J-shapedcannula, mtflw &xm was insrailed and 65 an f r a n the tip d the cannula, valve unit whi& canposg d inflw and cutflw valves was insemxi Lhing dastde, blood was sucked f r a n the right ventricle into the blaxipump.~g.syslde,bldwasejectedtothenrain-;lry artay.circulanry w perfamed using AH cfiver. Animal experhmt W3. s PerfaTlEd using goats weighting 5060 kg. Qrdx cu@ut(CO)a a d c press ('4@E),-;ny w Pr=e(P;tp) was m n i n x d m d g. S/D s%, PR 60 bpn , A "-was dtained In the animal expahent, after positicning d natural heart upside &r, vn wi& staM&r,COclrreasedfran SVmin to3.7 Vmin andAop&mzsedfi-an lDommHg to 60mdIg. Aftm startingdHeartC4Bassist,hen@mam 'csimprwedwith the i n c r~d C O ,~s o 3 i c ' 4 @ p (~t o B o m d I g) andP;t+dZ€b4 xmnHg), Gndudcns; Heart C4B was thcught to maintain s 8 b l e h~a m i c s c h r i n g dfpunpcABG lmmdu,Kcu Inrrhi*,Yusuke Abe*, lSune0 Chinzei,'hijirm Suech**Jept. d Carciwasc. Surg., MA7D4 Hcspiral.*Univ,dT~y~**Univ,dHircshirna R&Q;M;udmum ~f l~d 3 I l / n n r c j y s P 3 1 0 m m H g , L h t. P 150. . HIGHPRESUURE OCLZUSON OFLEUKOLYTE DEPLETlON ARTERIAL LINE FILTER IN PATIENTS WITH CARDIO-PULMONARY BYPASS SURGERY Cardw-pulmonary bypass (CPB) leads the activation of neutrophil, which may cause re-perfusion organ dysfunction. Utility of using the leukocyte depletion arterial filter tu prelendpostopcrative complications has been reported. The other side, the i&k of the leukocyte depletion filer occlusion with high-pressures of CPB arterial line (hi@pressure occlusion) has been noted. We used the leukocyte deletion filter (LG-6, RUj, and experienced two cases of high-pressure occlusion in 421 L~B surgery with LG-6 (0.48%). No high-pressure occlusion was occurred with 150R patients used the standard arterial tine filler in it period (0%. P=OoO7). lo the both cases of high pressure occlusion, monitored arterial line pressure increased to over 34OmmHg within lhininutes after CPB installation. The filters were changed to standard type, then no more filter trouble was occurred. In the second case, we inspected the occluded LG-6. Leht microscopic swvey showed eosin stained small spherical celk and ncgative lor fibrin. Electromicroscopy revealed that spherical cells (1-Zpm) adhered lo StrUCNre of the fBer. No fibrin was detected with Gel elechophoresis. Because of the pathologic znalysis, the c e k , which mighl cause the filer occlusion, were platelet. In addition, no fibrin exist suggese that the coagulation system did not relate to the high-pressure occlusion. lo conclusions, we experienccd hvo high-pressure occlusion cases of the leukocyte depletion arterial filter with CPB surgery (0.48%); the filter occhsion may be caused by the initid thmmhs formation by platelet.
Kardiovasculäre Medizin, 1999
European Journal of Cancer, 1992
Acknowledgements-We would like to thank Grace Chojnowski for flow cytometric analysis of DNA cont... more Acknowledgements-We would like to thank Grace Chojnowski for flow cytometric analysis of DNA content and Irene Perkic for help in preparation of the manuscript. S.D. was supported by the Myra DeGroot Foundation.
medicalforum.ch
... Matthias K. Widmer, Daniela Michallik, Hendrik Tevaearai, Juerg Schmidli, Thierry Carrel Klin... more ... Matthias K. Widmer, Daniela Michallik, Hendrik Tevaearai, Juerg Schmidli, Thierry Carrel Klinik für Herz-und Gefässchirurgie, Universitätsspital Bern ... Präsentieren Sie den Text auf eine logische Art und Weise («roter Faden») zum Beispiel mit Untertiteln (Einleitung, Methoden ...
The Journal of extra-corporeal technology, 2003
Vacuum-assist venous drainage (VAVD) can increase venous blood return during cardiopulmonary bypa... more Vacuum-assist venous drainage (VAVD) can increase venous blood return during cardiopulmonary bypass (CPB) procedures. However, the negative pressure created in the closed cardiotomy reservoir can be transmitted to the oxygenator if a nonocclusive or centrifugal arterial pump is used, resulting in bubble transgression (BT) from the gas to blood compartment of the oxygenator. We analyzed the vacuum pressure required to produce BT using an in vitro circuit including successively a closed reservoir, a pump (centrifugal or roller), and an oxygenator. A constant hydrostatic pressure was maintained onto the oxygenator. Vacuum was applied on the cardiotomy reservoir, progressively increasing negative pressure from 0 to -80 mmHg and monitoring BT with a bubble detector. Six different oxygenators were compared. A partially occlusive roller pump and a centrifugal pump were compared to a control, which was without any pump. A mean negative pressure of -53 +/- 7 mmHg was necessary to produce BT ...
Minimally invasive cardiac surgery requires a learning period before the advantages of the method... more Minimally invasive cardiac surgery requires a learning period before the advantages of the method can be demonstrated. We report the progress of our results over 21 consecutive months. 27 patients were considered for minimally invasive coronary bypass via a small thoracotomy. We compare the results of four consecutive groups corresponding to an initial period (July-December 1997; n = 7; 66.8 +/- 8.9 years), an intermediate period (January-June 1998; n = 4; 48.1 +/- 11.2 years), an advanced period (July-December 1998; n = 7; 62.9 +/- 7.0 years) and a current period (January-March 1999; n = 7; 59.3 +/- 10.9 years). 2 patients were converted to sternotomy during the first year of experience. The operating time was reduced from 124 +/- 14 min and 118 +/- 20 min during the initial and intermediate periods to 99 +/- 18 and 98 +/- 18 min during the last two periods. The ICU stay was 2.6 +/- 1.1 days during the initial period and diminished respectively to 1.5 +/- 0.6, 1.7 +/- 0.8 and 1.6 +/- 0.5 days during the intermediate, advanced and current periods. The postoperative hospital stay was reduced from 9.0 +/- 1.4 days to 6.3 +/- 4.6, 5.2 +/- 1.7 and 5.9 +/- 1.5 days respectively. The benefits of minimally invasive coronary bypass were estimated by comparing the results of the last two periods with those of patients operated on through a sternotomy, on a beating heart (n = 12; 62.6 +/- 8.2) or under CPB (n = 81; 63.0 +/- 8.5). In these situations, operative time was 144 +/- 41 min and 180 +/- 35 min respectively. The ICU stay was 1.5 +/- 0.6 and 2.2 +/- 0.9 days, and the postoperative hospital stay was 7.5 +/- 2.8 and 8.6 +/- 3.0 days. We conclude that a learning period is necessary before the real benefits of the minimally invasive approach to coronary disease can be demonstrated. This method will soon replace traditional sternotomy in certain indications
ASAIO Journal, 2001
The efficiency of left ventricular assist devices (LVADs) depends on the capacity of the inflow c... more The efficiency of left ventricular assist devices (LVADs) depends on the capacity of the inflow cannula to drain blood into the pump. Left atrial (LA) and left ventricular (LV) sites were compared in an animal model mimicking different hemodynamic conditions. Three calves (56.3+/-5.0 kg) were equipped with a Thoratec LVAD. A regular cardiopulmonary bypass (CPB) circuit was used as a right ventricular assist device (RVAD) (jugular vein/pulmonary artery), and preload conditions were adjusted by storage (or perfusion) of blood into (or from) the venous reservoir. LA and LV drainage, tested separately or simultaneously, was measured by its effect on the LVAD's performance. The LVAD was used alone on a beating heart or together with the RVAD (biVAD) on a beating and on a fibrillating heart. Increasing the central venous pressure (CVP) highlighted the differences between the LA and LV cannulation sites when the LVAD was tested either alone or together with the RVAD (biVAD) on a beating heart. Drainage through the LA or the LV was similar when CVP was set at 8 mm Hg, and increasing CVP to 14 mm Hg allowed for better drainage through the LV cannula. In contrast, after induction of fibrillation to mimic extreme heart failure, the drainage was better through the LA cannula. Using both LA and LV cannulae simultaneously did not improve the LVAD output in any of the conditions tested. LV cannulation provides better blood drainage when used on a normal beating heart and, therefore, allows for increased LVAD performance. However, in severe heart failure, blood drainage through the LV cannula decreases and the LA cannulation site is superior.
ASAIO Journal, 2001
LwEBMENT CF R I m VENIRICULAR m s T m c E (mm) mNGmPuMPc4EiG 'lbmaintain stablehen-@mamicsdning d... more LwEBMENT CF R I m VENIRICULAR m s T m c E (mm) mNGmPuMPc4EiG 'lbmaintain stablehen-@mamicsdning dfpumpC4BGA right ventricular assist &vice named Heart C M was c k v e l~p u r p o S e ; In this stu&,pump pa-famances were waluated in vitro and in viva Mataials and MeQ-c9B was canpcsed d blccd pump(ciaphragm type, strdce vdumeBml) andcannula(cuter ciam Umm,Iength Ban). At the tip d the J-shapedcannula, mtflw &xm was insrailed and 65 an f r a n the tip d the cannula, valve unit whi& canposg d inflw and cutflw valves was insemxi Lhing dastde, blood was sucked f r a n the right ventricle into the blaxipump.~g.syslde,bldwasejectedtothenrain-;lry artay.circulanry w perfamed using AH cfiver. Animal experhmt W3. s PerfaTlEd using goats weighting 5060 kg. Qrdx cu@ut(CO)a a d c press ('4@E),-;ny w Pr=e(P;tp) was m n i n x d m d g. S/D s%, PR 60 bpn , A "-was dtained In the animal expahent, after positicning d natural heart upside &r, vn wi& staM&r,COclrreasedfran SVmin to3.7 Vmin andAop&mzsedfi-an lDommHg to 60mdIg. Aftm startingdHeartC4Bassist,hen@mam 'csimprwedwith the i n c r~d C O ,~s o 3 i c ' 4 @ p (~t o B o m d I g) andP;t+dZ€b4 xmnHg), Gndudcns; Heart C4B was thcught to maintain s 8 b l e h~a m i c s c h r i n g dfpunpcABG lmmdu,Kcu Inrrhi*,Yusuke Abe*, lSune0 Chinzei,'hijirm Suech**Jept. d Carciwasc. Surg., MA7D4 Hcspiral.*Univ,dT~y~**Univ,dHircshirna R&Q;M;udmum ~f l~d 3 I l / n n r c j y s P 3 1 0 m m H g , L h t. P 150. . HIGHPRESUURE OCLZUSON OFLEUKOLYTE DEPLETlON ARTERIAL LINE FILTER IN PATIENTS WITH CARDIO-PULMONARY BYPASS SURGERY Cardw-pulmonary bypass (CPB) leads the activation of neutrophil, which may cause re-perfusion organ dysfunction. Utility of using the leukocyte depletion arterial filter tu prelendpostopcrative complications has been reported. The other side, the i&k of the leukocyte depletion filer occlusion with high-pressures of CPB arterial line (hi@pressure occlusion) has been noted. We used the leukocyte deletion filter (LG-6, RUj, and experienced two cases of high-pressure occlusion in 421 L~B surgery with LG-6 (0.48%). No high-pressure occlusion was occurred with 150R patients used the standard arterial tine filler in it period (0%. P=OoO7). lo the both cases of high pressure occlusion, monitored arterial line pressure increased to over 34OmmHg within lhininutes after CPB installation. The filters were changed to standard type, then no more filter trouble was occurred. In the second case, we inspected the occluded LG-6. Leht microscopic swvey showed eosin stained small spherical celk and ncgative lor fibrin. Electromicroscopy revealed that spherical cells (1-Zpm) adhered lo StrUCNre of the fBer. No fibrin was detected with Gel elechophoresis. Because of the pathologic znalysis, the c e k , which mighl cause the filer occlusion, were platelet. In addition, no fibrin exist suggese that the coagulation system did not relate to the high-pressure occlusion. lo conclusions, we experienccd hvo high-pressure occlusion cases of the leukocyte depletion arterial filter with CPB surgery (0.48%); the filter occhsion may be caused by the initid thmmhs formation by platelet.
Kardiovasculäre Medizin, 1999
European Journal of Cancer, 1992
Acknowledgements-We would like to thank Grace Chojnowski for flow cytometric analysis of DNA cont... more Acknowledgements-We would like to thank Grace Chojnowski for flow cytometric analysis of DNA content and Irene Perkic for help in preparation of the manuscript. S.D. was supported by the Myra DeGroot Foundation.
medicalforum.ch
... Matthias K. Widmer, Daniela Michallik, Hendrik Tevaearai, Juerg Schmidli, Thierry Carrel Klin... more ... Matthias K. Widmer, Daniela Michallik, Hendrik Tevaearai, Juerg Schmidli, Thierry Carrel Klinik für Herz-und Gefässchirurgie, Universitätsspital Bern ... Präsentieren Sie den Text auf eine logische Art und Weise («roter Faden») zum Beispiel mit Untertiteln (Einleitung, Methoden ...
The Journal of extra-corporeal technology, 2003
Vacuum-assist venous drainage (VAVD) can increase venous blood return during cardiopulmonary bypa... more Vacuum-assist venous drainage (VAVD) can increase venous blood return during cardiopulmonary bypass (CPB) procedures. However, the negative pressure created in the closed cardiotomy reservoir can be transmitted to the oxygenator if a nonocclusive or centrifugal arterial pump is used, resulting in bubble transgression (BT) from the gas to blood compartment of the oxygenator. We analyzed the vacuum pressure required to produce BT using an in vitro circuit including successively a closed reservoir, a pump (centrifugal or roller), and an oxygenator. A constant hydrostatic pressure was maintained onto the oxygenator. Vacuum was applied on the cardiotomy reservoir, progressively increasing negative pressure from 0 to -80 mmHg and monitoring BT with a bubble detector. Six different oxygenators were compared. A partially occlusive roller pump and a centrifugal pump were compared to a control, which was without any pump. A mean negative pressure of -53 +/- 7 mmHg was necessary to produce BT ...