Pulsatile Group Research Articles

The effect of pulsatile perfusion on cerebral blood flow during profound hypothermia with total circulatory arrest: A randomized, prospective, double-blind study

In 39 mongrel dogs, regional cerebral blood flow was measured during pulsatile and nonpulsatile deep hypothermic cardiopulmonary bypass with total circulatory arrest. Total circulatory arrest was performed at 20° C cerebral temperature for 40 minutes in 15 dogs, 60 minutes in 12 dogs, and 80 minutes in 12 dogs. Cerebral blood flow in both groups decreased as cerebral temperature fell and there was no significant difference in cerebral blood flow between the two groups during the cooling period. After circulatory arrest for 40 minutes, as cerebral temperature increased to 35° C, cerebral blood flow in both groups recovered to values as high as the respective initial values, which were measured just after the beginning of cardiopulmonary bypass for cooling (102.5% ± 10.2% in the pulsatile group and 97.2% ± 12.6% in the nonpulsatile group). After circulatory arrest for 60 minutes, cerebral blood flow in the pulsatile group increased to 141.8% ± 16.1% of its initial value when the cerebral temperature became 35° C, but it remained significantly lower (64.5% ± 9.2%) in the nonpulsatile group ( p < 0.01). After circulatory arrest for 80 minutes, cerebral blood flow in both groups remained lower than the respective initial values. These results suggest that pulsatile perfusion maintains cerebral blood flow even during profound hypothermia and that it may protect the brain from ischemic and hypoxic damage caused by profound hypothermia and total circulatory arrest in cardiac operations. (J T HORAC CARDIOVASC SURG 1994;108:119-25)

Evaluation of the pulsatility of a new pulsatile left ventricular assist device—the integrated cardioassist catheter—in dogs

A new pulsatile left ventricle-femoral artery bypass system (integrated cardioassist catheter system) has been developed for rapid, percutaneous insertion as a left ventricular assist device. Previous experiments revealed its superiority over the intraaortic balloon pump system in maintaining the peripheral circulation and in improving myocardial blood flow and afterload. Our objective was to determine whether the pulsatility of left ventricular bypass of this system would be preferable for maintaining the peripheral circulation and managing the ischemic myocardium as compared with nonpulsatile left ventricular bypass. Ten dogs with profound heart failure were supported by this system. Their hemodynamic status and myocardial blood flow were measured under control, nonpulsatile left ventricular bypass, or synchronous pulsatile left ventricular bypass. Significant differences between the nonpulsatile bypass group and the pulsatile bypass group were observed in the mean increase in aortic pressure (3.5% versus 22.2%, respectively; p < 0.001), total cardiac output (13.0% versus 21.7%; p = 0.004), and myocardial blood flow (9.5% versus 21.8%; p < 0.001). No differences were found between groups in the decrease in left atrial pressure (-20.2% versus -20.2%; p > 0.05). The ratio of diastolic time index/tension time index was shown to be improved significantly in the pulsatile bypass group compared with that of control and nonpulsatile bypass groups (p < 0.001). Thus, the pulsatility of the integrated cardioassist catheter system may support the peripheral circulation and improve the myocardial blood flow and oxygen supply/demand ratio.

Comparison of exogenous gonadotropins and pulsatile gonadotropin-releasing hormone for induction of ovulation in hypogonadotropic amenorrhea.

To compare the efficacy and safety of ovulation induction with exogenous gonadotropins vs. pulsatile GnRH in patients with hypogonadotropic amenorrhea, results from 30 patients in 111 cycles of gonadotropins and 41 patients in 118 cycles of pulsatile GnRH were analyzed retrospectively. Exogenous gonadotropins were administered using an individually adjusted protocol, using a starting dose of 150 IU. Pulsatile GnRH was delivered iv at a physiological frequency based upon our normative data. The doses administered ranged from 75-250 ng/kg. Preovulatory serum estradiol (E2) and luteal phase progesterone (P) levels were compared to those in normal cycling women (n = 87). The mean body mass index, age, and baseline gonadotropin levels were similar in the two groups. Overall ovulatory rates and conception rates per cycle and per patient were not significantly different between the two groups. However, the cumulative chance of conception after six cycles of treatment by life table analysis appeared to be higher with pulsatile GnRH treatment (96%) than with exogenous gonadotropins (72%). The risk of multiple gestation was also higher with exogenous gonadotropins (14.8% vs. 8.3%), although this was not statistically significant. All higher order multiple gestations (triplets or more) occurred in the gonadotropin-treated group. More than two dominant follicles were seen on ultrasound in 47.6% of gonadotropin-treated cycles compared to 18.9% of cycles with pulsatile GnRH treatment (P < 0.01). Three or more follicles were seen in 16.6% of the gonadotropin cycles compared to 5.4% with pulsatile GnRH (P < 0.05). No case of severe ovarian hyperstimulation was observed in either group, although the mean luteal phase ovarian size was significantly higher in the gonadotropin group (P < 0.05). Mean peak preovulatory E2 levels were significantly higher in the gonadotropin group (1684.5 +/- 124.4 vs. 1315.3 +/- 74.9 pmol/L; P < 0.05). The mean luteal phase P level 1 week after ovulation was significantly higher than normal in the gonadotropin group (84.9 +/- 10.8 vs. 61.1 +/- 3.2 nmol/L; P < 0.05), but was not significantly different from that in the pulsatile GnRH group (70.3 +/- 6.0 nmol/L). We conclude that pulsatile GnRH, when compared to exogenous gonadotropins, results in high rates of ovulation and conception, but a decreased risk of multiple folliculogenesis, higher order multiple gestations, and ovarian enlargement.(ABSTRACT TRUNCATED AT 400 WORDS)

The Renin‐Angiotensin‐Aldosterone System and Hematologic Changes During Pulsatile and Nonpulsatile Cardiopulmonary Bypass

The effects of pulsatile and nonpulsatile cardiopulmonary bypass using a roller pump on levels of vasoactive hormones and hematologic changes were studied in 32 patients subjected to elective primary coronary artery bypass graft surgery. Seventeen patients had nonpulsatile perfusion (nonpulsatile group) and 15 patients had pulsatile perfusion (pulsatile group) during the period of cardiac arrest. Vasoactive hormones (plasma renin, angiotensin II, aldosterone, epinephrine, and norepinephrine) were measured in these patients. In order to clarify hematologic changes, plasma free hemoglobin, number of platelets, platelet factor 4, and beta-thromboglobulin were measured. There were no significant differences between the pulsatile and nonpulsatile groups with regard to vasoactive hormones and damage of platelets. In the pulsatile group, however, the rise of plasma free hemoglobin levels was significantly higher than that in the nonpulsatile group during and after cardiopulmonary bypass. We did not see the benefit of pulsatile perfusion using a roller pump on vasoactive hormones. Evidence of increased hemolysis with pulsatile flow was demonstrated in our cases.

Effects of synchronous pulsatile extracorporeal membrane oxygenation in an endotoxin-induced shock model: an experimental study.

A synchronous pulsatile venoarterial device for extracorporeal membrane oxygenation (ECMO) was designed to accomplish more effective circulatory support for neonates. The effect of this device was studied using an endotoxin-induced shock model, compared with conventional nonpulsatile ECMO. Twenty puppies weighing 1.6 to 4.0 kg were given endotoxin (5 mg/kg) intravenously. Thirty minutes after the administration of endotoxin, 10 were placed on pulsatile ECMO, and the others were placed on nonpulsatile ECMO, and they were studied for an additional 180 min. Peak blood pressure, arterial pH, base excess, and renal blood flow were significantly higher in the pulsatile group than in the nonpulsatile group. Serum lactate and serum noradrenaline were significantly lower in the pulsatile group than in the nonpulsatile group. These results indicate that pulsatile ECMO may provide more effective cardiopulmonary support in the treatment of neonates with serious circulatory failure that has failed to be supported by nonpulsatile ECMO.

Intraabdominal complications after cardiopulmonary bypass

Thirty-three intraabdominal complications occurred in 27 patients over a 16-year period in 4,629 patients who underwent cardiopulmonary bypass (0.58% incidence). The mortality was 14.8% for the intraabdominal complication group compared with 3.4% for the control group of patients ( p < 0.01). The most common complication was gastrointestinal hemorrhage (n = 20), of which esophagitis (n = 6) was the most common cause. However, patients with duodenal ulcer (n = 4) had the highest mortality; 2 patients who underwent truncal vagotomy and pyloroplasty subsequently died. Two further patients underwent operation for perforated anterior duodenal ulcers without further morbidity. Cholecystitis developed in 5 patients and acute pancreatitis in 4; all were managed nonoperatively with no mortality. Multisystem organ failure developed in 2 patients, of whom 1 died. There was a significant correlation between intraabdominal complications and prolonged bypass time. The mean bypass time was 96.7 ± 28.6 minutes for the patients with gastrointestinal complications, compared with 81.7 ± 48.4 minutes for the whole group ( p < 0.01). No correlation was demonstrated for type of operation undergone or the age of the patient. In the last 5 years, 2,145 patients underwent cardiopulmonary bypass, of whom 562 received pulsatile and 1,583 nonpulsatile flow. The incidence of intraabdominal complications was 0.18% (n = 1) in the pulsatile group compared with 0.63% (n = 10) for the nonpulsatile group ( p = 0.14). Intraabdominal complications, although of low incidence, carry a significantly high mortality, and the clinician must be alert in the postoperative period to institute early therapy.

Plasma levels of glucose, insulin and cortisol in children undergoing cardiac surgery: effects of pulsatile and nonpulsatile perfusion

The effects of pulsatile and nonpulsatile perfusion on the plasma glucose, insulin and cortisol levels were studied in 12 children undergoing intracardiac repair of congenital heart defects. Hyperglycaemia was noted in both subgroups during the operation but plasma glucose returned to normal levels at 24 hours. Insulin secretion was suppressed during the period of extracorporeal circulation (ECC) and this was pronounced while the aorta was crossclamped. Cortisol levels were elevated during the whole period of study and remained elevated at 24 hours. In the pulsatile group cortisol levels were higher than the nonpulsatile group. However there was no significant difference between the groups. Like adults, children exhibit a metabolic response during open-heart operations. Pulsatile perfusion delivered by a modified Stöckert roller pump during ECC, did not alter the glucose, insulin and cortisol response to cardiac surgery in this study.

The effect of continuous or pulsatile administration of oxytocin to ewes at 126 to 136 days' gestation on myometrial activity and fetal oxygenation

Oxytocin was infused either continuously or in pulses to pregnant ewes to compare the responses of myometrial activity (contractures) and changes in fetal arterial PO2. Group 1 (n = 5) was infused with saline solution throughout the experiment. In group 2 (n = 5) oxytocin was infused continuously (160 microU.kg-1.min-1) for 7 days whereas group 3 (n = 5) ewes received 960 microU.kg-1.min-1 for 5 minutes every 30 minutes for 7 days. Contracture frequency increased in both oxytocin-infused groups. With continuous infusion contracture frequency returned to preinfusion levels during the last 4 days of infusion, whereas the pulsatile infusion contracture frequency remained increased throughout the infusion period. Fetal arterial PO2 was decreased throughout the 7 days of infusion in both oxytocin-infused groups. Pulsatile group fetal arterial PO2 levels remained decreased after the oxytocin infusion was stopped. These findings show: (1) Myometrial response to oxytocin in late pregnant ewes is influenced by the mode of administration; (2) administration of oxytocin to pregnant ewes resulted in a decrease in fetal PO2, and thus fetal hypoxemia cannot be attributed exclusively to increased contracture frequency.

Transcapillary forces of the subcutaneous tissue in patients with coronary artery disease: a comparison between pulsatile and nonpulsatile flow during extracorporeal circulation

The aim of this study was to evaluate subcutaneous transcapillary fluid balance during pulsatile and nonpulsatile extracorporeal circulation (ECC). Changes in the transcapillary fluid balance were studied by measuring subcutaneous interstitial fluid pressure (Pif) using the 'wick in needle' (WIN) method, as well as measuring subcutaneous interstitial fluid colloid osmotic pressure (COPif), using either the wick technique or the blister suction technique. The measurements were performed on the chest wall at the heart level. Simultaneous recordings of plasma colloid osmotic pressure (COPpl) were carried out. Nineteen male patients undergoing aortocoronary bypass grafting were subjected to nonpulsatile flow (group I, n = 11) or pulsatile flow (group II, n = 8) during ECC. Preoperatively there was no difference in the Starling forces between the two groups. During ECC the COP gradient (COPpl-COP if) was reversed to the same extent in the two groups. At three hours and six hours following ECC, COPif in the pulsatile group (12.1 mmHg and 11.4mmHg respectively) was significantly higher than in the nonpulsatile group (10.8mmHg and 10.3mmHg respectively). When weaning from ECC as well as three hours and six hours following ECC, Pif in the pulsatile group was significantly lower than in the nonpulsatile group. Conclusion: in the early postoperative period there is less dilution of the subcutaneous interstitial tissue following application of pulsatile flow during ECC compared to nonpulsatile flow.

Thromboxane and prostacyclin changes during cardiopulmonary bypass with and without pulsatile flow

Nonpulsatile cardiopulmonary bypass, in patients with coronary artery disease, produces a significant increase in thromboxane, a potent platelet aggregant and putative coronary vasoconstrictor. Pulsatile flow may decrease the incidence of perioperative infarction and the hormonal stress response to bypass. This study assessed the effect of pulsatile blood flow on plasma thromboxane and prostacyclin profiles during cardiopulmonary bypass by serial measurement of their stable metabolites, thromboxane B2 (TxB2) and 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha). Two groups of eight patients each were studied before, during, and after cardiopulmonary bypass. Eight patients had routine (nonpulsatile) bypass and eight had pulsatile flow. In the nonpulsatile group, the TxB2 concentration significantly increased during bypass (65 +/- 39 to 1,224 +/- 306 pg/ml, p less than 0.01) and rapidly returned to control. Prostacyclin also rose (53 +/- 20 to 613 +/- 132 pg/ml, p less than 0.01). In the pulsatile group, TxB2 rose during bypass (53 +/- 18 to 693 +/- 130 pg/ml, p less than 0.01), but peak concentration was significantly lower than in the nonpulsatile group (1,224 +/- 306 versus 693 +/- 130 pg/ml, p less than 0.05). Prostacyclin rose sharply during cardiopulmonary bypass in the pulsatile group (53 +/- 22 to 1,033 +/- 136 pg/ml, p less than 0.01) and was higher than in the nonpulsatile group (1,033 +/- 136 versus 325 +/- 33 pg/ml, p less than 0.01). There were no intragroup differences of plasma hemoglobin, hematocrit, or platelet count. These data demonstrate that pulsatile flow significantly alters prostacyclin and thromboxane profiles during cardiopulmonary bypass and favors production of the coronary vasodilator and platelet disaggregant prostacyclin. This may be an important factor in some of the clinical advantages previously reported with this modality.

The amylase-creatinine clearance ratio following cardiopulmonary bypass

The incidence of unexplained pancreatitis in patients dying after cardiac operations has been recorded as 16%, with evidence to implicate ischemia in the pathogenesis of the pancreatitis. Increased amylase--to--creatinine clearance ratios (ACCR), suggesting pancreatic dysfunction, have been reported in patients following nonpulsatile cardiopulmonary bypass (CPB). Pulsatile CPB is increasingly recognized to be a more physiological form of perfusion, particularly with respect to capillary blood flow. In this study the ACCR has been determined before, during, and after cardiac operations performed with both nonpulsatile and pulsatile CPB. Twenty patients undergoing elective cardiac operations were studied. Ten patients had nonpulsatile CPB (nonpulsatile group) and 10 had pulsatile CPB (pulsatile group). The two groups were comparable as regards perioperative variables and perfusion parameters. In both groups the ACCR was estimated preoperatively, on three occasions during the operation, and daily on the first 5 postoperative days. A significant elevation in ACCR was observed in nine of 10 patients in the nonpulsatile group but in only one of 10 patients in the pulsatile group (p less than 0.001). The significant improvement of ACCR stability following pulsatile CPB may indicate that this form of perfusion will reduce the risk of pancreatitis following cardiac operations performed with CPB.

Application of pulsatile cardiopulmonary bypass for profound hypothermia in cardiac surgery.

Profound hypothermia with core cooling has been considered unsafe as compared with surface cooling because of the induced metabolic acidosis. We carried out studies on mongrel dogs to determine whether or nor conventional cardiopulmonary bypass with pulsatile blood flow for core cooling could replace the bypass with non-pulsatile flow. The recovery time from anoxic damage of the brain due to circulatory arrest was also studied. Cerebral excess lactate (delta XL) (Huckabee) was determined throughout the course of hypothermia. During the cooling period from 30 degrees C down to 20 degrees C, the mean value of delta XL in the pulsatile group was significantly lower than that in the non-pulsatile group (p less than 0.01). After forty minutes of the first total arrest at 20 degrees C, thirty minutes of pulsatile perfusion tended to eliminate the anaerobic metabolism of the brain caused by the first total circulatory arrest (p less than 0.1). Thus, the anaerobic metabolism in the brain appears to be highly suppressed with pulsatile cardiopulmonary bypass during the cooling period. Correction of congenital heart disease in infancy can probably be more safely performed if pulsatile cardiopulmonary bypass for cooling and rewarming is employed instead of the non-pulsatile bypass.

Pulsatile perfusion versus conventional high-flow nonpulsatile perfusion for rapid core cooling and rewarming of infants for circulatory arrest in cardiac operation

Thirty consecutive infants undergoing hypothermia and circulatory arrest for repair of ventricular septal defect, transposition of the great vessels, or atrioventricular canal defects were alternately selected for conventional high flow nonpulsatile perfusion or pulsatile perfusion during core cooling and rewarming. All received morphine anesthesia, 30 mg/kg of Solu-Medrol, and 10 to 15 mcg/kg of phentolamine. Those receiving nonpulsatile flow were perfused at a rate of 160 to 180 cc/kg/min with a roller pump and oxygenator with arterial pressure of 50 to 55 mm Hg. In the pulsatile flow group, a roller pump and oxygenator were used, and an especially constructed Datascope PAD (pulsatile assist device) was interposed in the arterial line to provide pulsatile perfusion with 75/40 mm Hg pressure at slightly reduced flow (150 cc/kg/min). The average rectal, esophageal, and tympanic membrane temperatures were reduced to approximately 16 degrees C prior to circulatory arrest. Following repair, perfusion was resumed until these temperatures returned to 37 degrees C. Cooling and rewarming were enhanced by pulsatile perfusion, with over 30% reduction in total pump time. Additionally, the larger patients in the pulsatile group cooled almost as rapidly as the smaller. The rates of decline and subsequent rise of rectal, esophageal, and tympanic membrane temperatures were equal in the pulsatile group, but the rectal temperature lagged far behind in the nonpulsatile group. Urine production during bypass was 100% greater in the pulsatile group. The plasma free hemoglobin was similar in both groups. The average postrewarming pH was 7.31 in the nonpulsatile group and 7.42 in the pulsatile group. Infants receiving pulsatile flow awakened more quickly, were more alert, and required less postoperative mechanical ventilation. We suggest that pulsatile perfusion for core cooling and rewarming of infants is safe and is more rapid and physiological than conventional high-flow nonpulsatile perfusion.

Plasma vasopressin levels and urinary flow during cardiopulmonary bypass in patients with valvular heart disease: Effect of pulsatile flow

The effect of pulsatile flow on plasma vasopressin levels during cardiopulmonary bypass (CPB) was studied in 20 patients undergoing open valve replacement. Routine bypass was used in 10 patients and the AVCO pulsatile bypass pump was utilized in the other 10. In Group I (nonpulsatile) during CPB, the vasopressin level was markedly elevated (3.1 +/- 2 to 80 +/- 22 pg/ml) as was urine flow (0.6 +/- 0.2 to 5.9 +/- 2 ml/min) and urine Na+ concentration (69 +/- 19 to 116 +/- 7 mEq/L). In Group II (pulsatile) during CPB, the vasopressin level (3.8 +/- 3 to 54 +/- 14 pg/ml), urine flow (0.6 +/- 0.1 to 16.2 +/- 4.8 ml/min), and urine Na+ concentrations (61 +/- 13 to 97 +/- 10 mEq/L) were also elevated. The rise in vasopressin and urine Na+ was less in the pulsatile group (p less than 0.05) whereas the urine flow was higher (p less than 0.05). To maintain comparable blood pressure, the pulsatile flow group required significantly higher flows (4.5 +/- 0.2 compared to 3.8 +/- 0.2; p less than 0.05). These data suggest that CPB produces a marked vasopressin stress response which is beyond the physiological range for an antidiuretic effect on the kidney. At these levels vasopressin can exert a vasopressor effect to maintain resistance and affect renal blood flow, as well as producing an Na+ diuresis. The addition of pulsatile flow creates a more physiological situation attenuating the vasopressin response and producing a decrease in systemic resistance and a less pronounced Na+ diuresis.

Comparative studies of pulsatile and nonpulsatile flow during cardiopulmonary bypass: II. The effects on adrenal secretion of cortisol

Previous studies have indicated that a significant reduction in plasma cortisol levels occurs during nonpulsatile cardiopulmonary bypass as a result of adrenocorticol hypofunction. The Stöckert pulsatile pump system described in Part I has been employed in a comparative study of plasma cortisol levels in 20 patients subjected to pulsatile or nonpulsatile perfusion during open-heart surgery. The plasma cortisol response pattern in the nonpulsatile group was identical to the pattern previously described, with no significant rise in cortisol levels during the period of perfusion. In the pulsatile group, however, plasma cortisol levels rose significantly during perfusion, reaching a mean level at the end of perfusion which was highly significantly greater than that in the nonpulsatile group (p less than 0.001). Correction of the plasma cortisol values for the effect of hemodilution was performed and, again, corrected cortisol values indicated a highly significant increase in end-bypass levels in the pulsatile groups (p less than 0.001). These results clearly indicate that the reduction in cortisol secretion during nonpulsatile bypass may be prevented by the use of pulsatile perfusion.

Comparative studies of pulsatile and nonpulsatile flow during cardiopulmonary bypass: III. Response of anterior pituitary gland to thyrotropin-releasing hormone

Previous studies have indicated that, during nonpulsatile cardiopulmonary bypass, the anterior pituitary gland fails to respond to the tropic stimulus of thyrotropin-releasing hormone (TRH). This is in contrast to the normal response seen during closed cardiac and general surgical procedures. The Stöckert pulsatile pump system described in Part I has been employed in a comparative study of TRH responses in 20 patients subjected to pulsatile or nonpulsatile perfusion during open-heart surgery. In the nonpulsatile group, a consistently subnormal response to TRH injection was again found. In the pulsatile group, however, the pituitary response to TRH was normal in nine patients out of 10. The quantitative difference between the groups was statistically highly significant (p less than 0.005). These results indicate that the subnormal pituitary function seen with nonpulsatile bypass may be prevented by the use of pulsatile perfusion.

Comparative studies of pulsatile and nonpulsatile flow during cardiopulmonary bypass: I. Pulsatile system employed and its hematologic effects

A new, commercially available roller pump system able to deliver pulsatile and nonpulsatile flow has been studied in patients undergoing elective open-heart surgical procedures. The pulsatile pump (Stöckert Instrumente) may be used with standard extracorporeal circuit equipment and consistently produces a peripheral arterial pulse pressure of 25 to 30 mm. Hg at mean flow rates of 3.5 to 4.0 L. per minute. Twenty patients, arbitrarily allocated to pulsatile or nonpulsatile groups, have been studied. There were no significant differences between the groups in respect of age, weight, bypass time, pump flow, or mean arterial pressure during bypass. Comparative studies of the hematologic effects of pulsatile and nonpulsatile perfusion were carried out. There was no evidence of increased hemolysis with pulsatile flow, nor was there increased depletion of red blood cells (RBC's) or platelets in the pulsatile group. This pulsatile pump system may therefore be used to produce pulsatile perfusion during cardiopulmonary bypass without the fear of producing excessive blood cell trauma.