Nonpulsatile Left Heart Bypass Research Articles

Visceral and Renal Tissue Oxygenation During Supraceliac Aortic Crossclamping and Left Heart Bypass with Selective Organ Perfusion

Introduction. Left-heart bypass (LHB) and selective organ perfusion (SOP) are used during thoracoabdominal aortic surgery to prevent ischemic damage to the kidneys and visceral organs after supraceliac aortic crossclamping. We studied the hypothesis, in a porcine model, that despite LHB and maximal SOP, visceral and renal ischemia still occured during surgery.Material and methods. Eleven pigs (54–70 kg) were coupled to a non-pulsatile LHB with inflow and outflow at the lower thoracic and distal infrarenal aorta, respectively. After supracoeliac and infrarenal aortic crossclamping, SOP was started using perfusion catheters. The proximal and distal mean aortic blood pressures were kept above 70 and 50 mmHg, respectively, while the mean blood pressure within the SOP system was above 60 mmHg. The visceral and renal tissue oxygenation was measured by intermittent blood gas analysis, from the portal and both renal veins. The jejunal mucosal oxygenation was measured by tonometric measurement of the luminal pCO2.Results. Measured median blood blood flow through the LHB and the SOP system were 800 and 1140 ml/min, respectively. Median blood flow prior to, and during LHB and SOP through the celiac artery, superior mesenteric artery, and left renal artery were 300 and 240, 762 and 295, and 235 and 235 ml/min, respectively. During 3 h of LHB and SOP no significant changes in the renal tissue oxygenation were noted compared with the physiological situation prior to supracoeliac aortic crossclamping and cannulation. However, in the visceral vascular bed median mixed venous oxygen saturation dropped from 79 to 63% (p<0.001), and median oxygen extraction ratio increased from 26 to 41% (p<0.001). Median tonometric measured intraluminal jejunal pCO2 increased from 9.9 to 12.15kPa (p>0.05). During 3 h of LHB and SOP no hemolysis was detected, as there was no rise in serum LDH.Conclusion. LHB and SOP preserves renal but not visceral tissue oxygenation during supraceliac aortic crossclamping and does not induce hemolysis.

Did Ündar and Associates Really Make Those Comments on the Issue of Pulsatile Versus Nonpulsatile Flow? Absolutely Not.

Did Ündar and Associates Really Make Those Comments on the Issue of Pulsatile Versus Nonpulsatile Flow? Absolutely Not.

Influence of varying conduit resistance on native heart function with nonpulsatile left heart bypass

Nonpulsatile left heart bypass (NPLHB) represents a new era in cardiac support. We examined the impact of circuit resistance on ventricular loading with NPLHB. Pressure head-flow (H-Q) curves of NPLHB were measured with four grades of circuit resistance in a mock circulation. Lower resistance result, in a shallower H-Q relationship. Based on this results, NPLHB (ventricular apex to descending aorta) with ratios of 75% and 100% was evaluated for its hemodynamic effect in seven anesthetized sheep. Two grades of circuit resistance were generated with each bypass flow. A shallower H-Q relationship was noted at the lower circuit resistance when increased bypass flow fluctuations occurred during a single cardiac cycle (75%:0.9 ±0.4 to 12.2±2.8,P<0.0001; and 100%: 0.6±0.1 to 2.3 ±1.2l/min,P=0.011, with higher and lower resistance, respectively). Improved left ventricular peak pressure also resulted (75%:112±9 to 104±8,P=0.0002; and 100%: 59±26 to 13±5 mmHg,P=0.0045). In conclusion, NPLHB with lower circuit resistance improves the bypass flow response to change in pressure head during the cardiac cycle. This results in increased systolic bypass flow and improved systolic pressure unloading. Therefore, circuit resistance needs to be taken into account when designing NPLHB systems and when assessing their pump effect.

Influence of Pulsatile and Nonpulsatile Left Heart Bypass on the Hormonal Circadian Rhythm

Influence of Pulsatile and Nonpulsatile Left Heart Bypass on the Hormonal Circadian Rhythm

Change in vasoconstrictive function during prolonged nonpulsatile left heart bypass.

We investigated changes in vasoconstrictive function accompanying prolonged nonpulsatile left heart bypass (NLHB). After 2-week pulsatile left heart bypass (PLHB) in 11 goats, NLHB was conducted for another 4 weeks (Group N) in 6 goats. In the other 5 goats, PLHB was continued for another 4 weeks (Group P). Systemic vascular resistance at rest (rSVR) was measured on the last days of the second and sixth postoperative week (W2 and W6, respectively). Subsequently, phenylephrine was injected, and the maximum values (SVRmax) and the maximum increasing change in SVR (DeltaSVR) were measured. No significant difference was observed in rSVR between groups at W2 or W6. The SVRmax and the DeltaSVR at W2 were consistent in both groups. However, at W6, the SVRmax and the DeltaSVR of Group N were significantly lower than those of Group P. In conclusion, prolonged NLHB caused a significant decrease in the SVR response to phenylephrine, indicating a dimunition of vasoconstrictive function.

MORPHOLOGICAL CHANGES OF THE ARTERIAL SYSTEMS IN THE KIDNEY UNDER PROLONGED NONPULSATILE LEFT HEART BYPASS

We previously reported atrophic changes of the aorta caused by prolonged reduced pulse pressure during nonpulsatile left heart bypass (NLHB). Prolonged NLHB possibly causes some changes to the peripheral regions of the arterial systems which play important roles on organ perfusion. The present study was carried out to investigate morphological changes of the arterial systems in the kidneys accompanying prolonged NLHB. A ventricular assist device (VAD) was paracorporeally installed between the left atrium and the descending aorta in 13 adult goats. After 2 weeks of pulsatile left heart bypass, the VAD was replaced with a centrifugal pump, and NLHB was subsequently conducted for 4 weeks (Group N). At the end of experiments, the kidneys were removed and subjected to pathological evaluation by light microscopic examination and immunohistochemical examination with antiproliferating cell nuclear antigen antibody (PCNA) to evaluate proliferating activity of the tissue. Six normal healthy goats were used as a control group (Group C). In the light microscopic examination, the renal arteries and their major branches showed no degeneration in both groups. However, in the peripheral areas of Group N, the walls of the afferent glomerular arterioles were thickened by an increase in number of the mature smooth muscle cells (SMC). The juxtaglomerular areas were expanded due to an increase in number and size of SMCs or SMC-like cells. Furthermore the ratio of PCNA stain-positive cells in these areas in Group N (4.1 ± 3.5 / juxtaglomerular area) were significantly increased (p <0.0001) compared with those in Group C (0.9 ± 0.9/juxtaglomerular area), indicating the active proliferation of these cells in these areas in Group N. In the biochemical examination, no perceptible changes in serum creatinine and blood urea nitrogen were observed in both groups. We conclude that prolonged NLHB causes proliferation of SMCs or SMC-like cells in the afferent glomerular arterioles and juxtaglomerular areas.

Effects of nonpulsatile left heart bypass on renal sympathetic nerve activity in rabbits.

To determine the effects of nonpulsatile left heart bypass (LHB) on sympathetic nerve activity the renal sympathetic nerve activity (RSNA) was directly measured in rabbits. In anaesthetized rabbits (n=6), LHB was instituted with a centrifugal pump. Before and during LHB, heart rate (HR), arterial pressure (AP), central venous pressure (CVP), left atrial pressure (LAP) and spike counts of RSNA were measured. After bilateral vagotomy (section of the afferent inputs of the cardiac reflex arc) the same parameters were measured before and during LHB. Data were obtained at the same level of mean AP before and during LHB. Mean AP and CVP were not changed by LHB before and after vagotomy. LAP was significantly decreased by LHB before and after vagotomy. RSNA and HR were not significantly changed by LHB before and after vagotomy. Our results clarify the complex baroreflex control during nonpulsatile LHB and indicate that RSNA is not altered by LHB.

Influence of Pulsatile and Nonpulsatile Left Heart Bypass on the Hormonal Circadian Rhythm

We investigated endocrine circadian rhythm (CR) during pulsatile and nonpulsatile left heart bypass (PLHB and NLHB). A ventricular assist device (VAD) was installed in five goats. After 2 weeks of PLHB, NLHB was subsequently conducted for 4 weeks. The levels of melatonin, cortisol, and renin activity were measured every 2 hours for 24 hours on the last day of the second PLHB week and the second and fourth NLHB weeks. Acquired data were compared with those of the normal control goats (Cont) to determine the presence or absence of CR, as well as the timing, acrophase, amplitude, and mesor of CR. Variations in melatonin, CR were consistently detected at all sampling points. In contrast, CR of cortisol during PLHB and NLHB was observed in a few cases, although considerable CR was noted in most of the Cont cases. The variations in renin activity indicated CR in most of the Cont cases and in all cases at all sampling points during PLHB and NLHB, whereas their acrophases were diversified. In conclusion, the CR of melatonin, reflecting the fundamental circadian clock, was maintained during both PLHB and NLHB, while it could be modified for stress sensitive cortisol and hemodynamic responsive renin during these bypass modalities.

Effects of reduced pulse pressure to the cerebral metabolism during prolonged nonpulsatile left heart bypass.

We investigated changes in the cerebral metabolism with long-term reduced pulse pressure. Nine goats underwent pulsatile left heart bypass (LHB) for 2 weeks while awake, and nonpulsatile LHB was subsequently conducted for 4 weeks. The average pulse pressure during nonpulsatile LHB (13, 10, 11, and 11 mm Hg at the 1st, 2nd, 3rd, and 4th nonpulsatile LHB week, respectively) was significantly lower than that during pulsatile LHB (36 mm Hg). There were no significant differences in either arterio-jugular venous oxygen differences (AJDO2) and cerebral oxygen extraction ratio between the 2nd pulsatile LHB week and the 1st, 2nd, 3rd, and 4th nonpulsatile LHB weeks. The arterio-jugular venous glucose differences, jugular venous-arterial lactate differences (JAD Lactate), and lactate oxygen indexes (JAD Lactate/AJDO2) also remained unchanged during the entire course of the experiments. In conclusion, the cerebral metabolism during nonpulsatile LHB did not change compared to that during pulsatile LHB.

Mechanical bridge to recovery in fulminant myocarditis

A patient with acute fulminant lymphocytic myocarditis and cardiogenic shock was successfully treated by mechanical offloading of the left ventricle. A nonpulsatile left-heart bypass was undertaken with an implantable centrifugal blood pump. Careful weaning resulted in device removal on the seventh day. Left and right ventricular function is sustained at 7 months. Widespread application of this method depends on the availability of an inexpensive user friendly blood pump, appropriate weaning protocols and emerging strategies to promote sustainabile myocardial recovery.

Effect of prolonged nonpulsatile left heart bypass on vascular control status

We investigated the vascular control status, including vasoactive hormones, systemic vascular resistance (SVR), and baroreceptor sensitivity, in prolonged nonpulsatile left heart bypass (NLHB). Nine goats underwent pulsatile left heart bypass (PLHB) with a ventricular assist device (VAD). Two weeks postoperatively, the VAD was replaced with a centrifugal pump and NLHB was subsequently conducted for 4 weeks. Thirteen healthy goats were also evaluated to obtain normal control data. The aortic pulse pressure on average was 37 mmHg for controls; 36mmHg at the end of PLHB; and 11, 9, 12, and 12mmHg at the end of the first, second, third, and fourth NLHB weeks, respectively. Plasma norepinephrine (NE), vaso-pressin (VP), renin activity (RA), and endothelin-I (ET) levels were measured for controls and at each point during PLHB and NLHB. The baseline SVR and the minimum SVR values after nitroglycerin injection were determined at each point during PLHB and NLHB. Baroreceptor sensitivity was calculated as the regression slope between R-R intervals and mean aortic pressure for controls and at each point during PLHB and NLHB. The plasma levels of NE, VP, RA, and EN did not change significantly during the entire course of the experiments. The baseline and minimum SVR values after nitroglycerin injection remained unchanged during PLHB and NLHB. Furthermore, the baroreceptor sensitivity did not change significantly during the entire course of the experiments. These results indicate that prolonged NLHB does not affect vascular control status, including the major vasoactive hormone levels, SVR, and baroreceptor sensitivity.

Aortic reaction to prolonged nonpulsatile left heart bypass

We investigated the reaction of the vascular system to prolonged nonpulsatile left heart bypass (LHB) using adult goats that underwent chronic nonpulsatile LHB. On morphological examination of the aorta, we found a decrease in wall thickness, a decrease in constituent volume ratio of smooth muscle, and an increase in the ratio of elastin. The atrophic change was further confirmed by an increase in smooth muscle cell density and an increase in smooth muscle cells, which exhibited atrophy-specific changes on electron microscopic observation. The changes in mechanical properties accompanying these morphological changes were evaluated according to stiffness parameter β and pulse wave velocity. No significant changes in those parameters were caused by prolonged nonpulsatile LHB. The change in vascular contractility was evaluated by the response of systemic vascular resistance to norepinephrine and nitroglycerin administration. Vascular contractility was markedly decreased by prolonged nonpulsatile LHB. These results indicated that the significant morphological changes, including aortic structure and smooth muscle atrophy, were caused by prolonged nonpulsatile LHB. However, these changes did not accompany the changes in mechanical properties. In contrast, this distinctive LHB modality caused a decrease in vascular contractility.

Effects of long-term nonpulsatile left heart bypass on the mechanical properties of the aortic wall.

We investigated the mechanical properties of the descending aortic wall relative to its structural change caused by reduced pulse pressure in long-term nonpulsatile left heart bypass (LHB). Fifteen adult goats (53-68 kg) were divided into three groups: five goats underwent LHB with a nonpulsatile pump for 31 to 381 days (Group N), five goats underwent LHB with a pulsatile pump for 24 to 130 days (Group P), and the other five goats were used as normal control animals (Group C). The aortic pulse wave pressure was 17+/-7 mm Hg in Group N, 43+/-1 mm Hg in Group P, and 39+/-2 mm Hg in Group C. Structural changes were evaluated using wall thickness and the volume ratio of elastin and collagen. The mechanical properties were evaluated using "beta," which was calculated according to the equation: = (In P/Ps)/(Do/Ds-1), where Ps was the standard pressure, Ds was the wall diameter at pressure Ps, and Do was the wall diameter at pressure P. The wall thickness of the aortic wall in Group N (1.6+/-0.3 mm) was significantly thinner than that in either Group P (2.2+/-0.3 mm) or Group C (2.1+/-0.2 mm). The volume ratio of elastin in Group N (51 +/- 3%) was higher than that in Group P (44+/-1%) or Group C (40+/-1%), whereas no significant difference was found in the volume ratio of collagen between those in Group N (10+/-1%), Group P (9+/-2%), and Group C (10+/-1%). The stiffness parameter, beta, in Group N (3.1+/-0.7) was slightly higher than that seen in Group P (2.9+/-0.4) or Group C (2.9+/-0.2), but there was no significant difference between the three groups. These results indicate that long-term nonpulsatile LHB caused marked structural changes in the aortic wall, whereas the change in mechanical properties were not significant with regard to stiffness.

Diminished vasoconstrictive function caused by long-term nonpulsatile left heart bypass.

We investigated the functional changes of the systemic vascular system due to prolonged nonpulsatile left heart bypass (NPLHB). Three adult goats underwent pulsatile left heart bypass (PLHB). Two weeks later the PLHB was changed to the NPLHB, which was conducted for 4 weeks. The aortic pulse pressure was 39 and 16 mm Hg during the PLHB and NPLHB, respectively. Systemic vascular resistance (SVR) and the plasma norepinephrine level were measured at the end of PLHB (PUL), and in the 1st, 2nd, 3rd, and 4th weeks of NPLHB (NP1w, NP2w, NP3w, and NP4w). At each point, 1 microg/kg norepinephrine was injected, and the elevation of the SVR (deltaSVR) was calculated. The SVR and the plasma norepinephrine level did not change significantly during the entire course. However, deltaSVR decreased during NPLHB and became significantly lower at NP3w and NP4w than that at PUL (NP3w: 839 +/- 164, NP4w: 746 +/- 268, and PUL: 1,239 +/- 324 dyne x s x cm(-5)). These results strongly indicated that prolonged NPLHB significantly diminished the constrictive function of the vascular system.

Prolonged Nonpulsatile Left Heart Bypass Diminishes Vascular Contractility

We investigated possible functional changes in the vascular system accompanying the morphological change in prolonged nonpulsatile left heart bypass (LHB). Three adult goats underwent pulsatile LHB. Two weeks postoperatively, the pulsatile ventricular assist device was replaced with a centrifugal pump and nonpulsatile LHB was subsequently conducted for 4 weeks. The mean aortic pulse pressure was 39 and 16 mmHg during the pulsatile and nonpulsatile LHB, respectively Systemic vascular resistance (SVR) and plasma norepinephrine levels were measured at the end of pulsatile LHB (PUL), and at the end of 1st, 2nd, 3rd, and 4th week of nonpulsatile LHB (NP1w, NP2w, NP3w, NP4w, respectively). At each point, 50 microg/kg nitroglycerin and 1 microg/kg norepinephrine were injected and the minimal and maximal values of SVR after injection were calculated as parameters reflecting the vascular tonus and contractility. The SVR and plasma nor epinephrine level did not significantly change during the entire course (SVR: 1106, 895, 982, 920, and 938 dyne x sec x cm(-5); norepinephrine level: 0.3, 0.2, 0.1, 0.2, and 0.1 ng/ml; at PUL, NP1w, NP2w, NP3w, and NP4w, respectively). The minimal value of SVR after nitroglycerin injection remained unchanged, indicating that vascular tonus was stable during the entire course (618, 687, 623, 560, 653 dyne x sec x cm(-5), respectively). In contrast, the maximal value of SVR after norepinephrine injection at NP3w and NP4w (1695 and 1759 dyne x sec x cm(-5)) became significantly reduced compared to that at PUL (2346 dyne x sec x cm(-5)). These results indicated that prolonged nonpulsatile left heart bypass did not affect the vascular tonus, but significantly diminished the vascular contractility.

Cardiac autonomic nervous function during long-term nonpulsatile left heart bypass.

We investigated the changes in cardiac autonomic nervous activities during long-term nonpulsatile left heart bypass (NLHB) by analyzing heart rate variability. A pulsatile ventricular assist device was installed in 3 goats, and pulsatile left heart bypass (PLHB) was conducted for 2 weeks. Then, NLHB was maintained for the following 4 weeks. The segmental data of the R-R intervals (R-Rs) was analyzed by maximum entropy spectral analysis. Changes in evaluated parameters from the last week of PLHB to the 4th week of NLHB were as follows: the mean R-Rs increased from 511 ms to 692 ms; the coefficient of variation of R-R increased from 10.2 to 14.1%; the power of the low frequency band (LF) increased from 747 ms2 to 2,855 ms2; the power of the high frequency band (HF) increased from 512 ms2 to 1,270 ms2; and the ratio of LF to HF increased from 2.6 to 6.5. These results indicated that the cardiac autonomic nervous activity, both sympathetic and parasympathetic, increased during long-term NLHB.

Organ blood flow during pulsatile cardiopulmonary bypass.

Organ blood flow during pulsatile cardiopulmonary bypass.

In Vivo Determination of Renal Tissue Oxygenation During Pulsatile and Nonpulsatile Left Heart Bypass

Data favoring pulsatile over nonpulsatile left heart bypass are conflicting. To study this problem, renal cortical and medullary tissue oxygen availability (O 2a) and total renal oxygen flow were compared with total renal oxygen consumption during four hours of pulsatile and nonpulsatile bypass in dogs. Although there was no difference in renal tissue O 2a during the first two hours, thereafter the decrease in renal O 2a was greater during nonpulsatile bypass; total renal blood flow was greater with pulsatile bypass, and at the given renal oxygen flow, renal oxygen consumption was greater during pulsatile bypass. These data, along with previous work, support the superiority of pulsatile bypass.

Renal tissue oxygenation during pulsatile and nonpulsatile left heart bypass.

Data favoring pulsatile over nonpulsatile left heart bypass are conflicting. To study this problem, renal cortical and medullary tissue oxygen availability (O2a) and total renal oxygen flow was compared with total renal oxygen consumption during four hours of pulsatile and nonpulsatile bypass in dogs.

Aortic nervous activities in response to pulsatile and nonpulsatile pressure.

ARTICLESAortic nervous activities in response to pulsatile and nonpulsatile pressureI Ninomiya, and H IrisawaI Ninomiya, and H IrisawaPublished Online:01 Dec 1967https://doi.org/10.1152/ajplegacy.1967.213.6.1504MoreSectionsPDF (2 MB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat Previous Back to Top Next Download PDF FiguresReferencesRelatedInformation Cited ByRegulation of breathing by cardiopulmonary afferentsDischarges of aortic and carotid sinus baroreceptors during spontaneous motor activity and pharmacologically evoked pressor interventions11 May 2014 | The Journal of Physiological Sciences, Vol. 64, No. 4Signal transduction of aortic and carotid sinus baroreceptors is not modified by central command during spontaneous motor activity in decerebrate catsKanji Matsukawa, Kei Ishii, Akito Kadowaki, Tomoko Ishida, Mitsuhiro Idesako, and Nan Liang15 May 2014 | American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, Vol. 306, No. 10Physiology of continuous blood flow in recipients of rotary cardiac assist devicesThe Journal of Heart and Lung Transplantation, Vol. 24, No. 3Sleep-related changes in baroreflex sensitivity and cardiovascular autonomic modulationJournal of Hypertension, Vol. 21, No. 8Change in Vasoconstrictive Function During Prolonged Nonpulsatile Left Heart BypassArtificial Organs, Vol. 25, No. 5Effect of xenon on autonomic cardiovascular control—comparison with isoflurane and nitrous oxideJournal of Clinical Anesthesia, Vol. 12, No. 3Effect of prolonged nonpulsatile left heart bypass on vascular control statusJournal of Artificial Organs, Vol. 3, No. 1Diminished Vasoconstrictive Function Caused by Long‐Term Nonpulsatile Left Heart Bypass24 December 2001 | Artificial Organs, Vol. 23, No. 8Prolonged Nonpulsatile Left Heart Bypass Diminishes Vascular Contractility13 March 2018 | The International Journal of Artificial Organs, Vol. 22, No. 7Arterial Baroreceptor Afferent Activity in Nonpulsatile Systemic Circulation4 January 2002 | Artificial Organs, Vol. 22, No. 12Characteristics of Sympathetic Nerve Activity During Nonpulsatile CirculationArterial Baroreceptor Regulation of Peripheral Resistance and of Cardiac PerformanceThe effects of pulsatile and non-pulsatile cardiopulmonary bypass on renal blood flow and functionThe Japanese Journal of Surgery, Vol. 19, No. 3PreLoad-responsive, Pulsatile-Flow, Externally Valved Pump: Cardiopulmonary Bypass9 July 2009 | Journal of Investigative Surgery, Vol. 2, No. 3An Analyzer for Autonomic Nerve Activities in Acute and Chronic AnimalsIEEE Transactions on Biomedical Engineering, Vol. BME-33, No. 1Sympathetic nerve activity: a link to stroke?Stroke, Vol. 16, No. 1Baroreflex Control of Systemic Arterial Pressure and Vascular Bed1 January 2011Pulsatile and Nonpulsatile Cardiopulmonary Bypass: Review of a Counterproductive ControversyThe Annals of Thoracic Surgery, Vol. 36, No. 6Association between sympathetic nerve activity and cerebrovascular protection in young spontaneously hypertensive rats.Stroke, Vol. 14, No. 1Coarctation of the aorta and baroreceptor resetting. A study of carotid baroreceptor stimulus-response characteristics before and after surgical repair in the dog.Circulation Research, Vol. 48, No. 3Cardiovascular neurography: Cardiac-rhythm based neurosignal distribution displayMedical & Biological Engineering & Computing, Vol. 18, No. 1A quantitative study of muscle nerve sympathetic activity in resting normotensive and hypertensive subjects.Hypertension, Vol. 1, No. 2Control of Vasomotor Function and the Hemodynamic Consequences of the Contractile Behavior of ArteriesTo Pulse or Not to PulseThe Annals of Thoracic Surgery, Vol. 25, No. 3Peak discrimination as a method for quantitative evaluation of neural activity by computerMedical & Biological Engineering, Vol. 13, No. 3Studies on the Arterial Baroreceptor Reflex SystemIFAC Proceedings Volumes, Vol. 6, No. 4 More from this issue > Volume 213Issue 6December 1967Pages 1504-1511 Copyright & PermissionsCopyright © 1967 by American Physiological Societyhttps://doi.org/10.1152/ajplegacy.1967.213.6.1504PubMed6075752History Published online 1 December 1967 Published in print 1 December 1967 Metrics