Comparison of pulsatile with nonpulsatile mechanical support in a porcine model of profound cardiogenic shock

The aim of this study was to examine whether pulsatility by intraaortic balloon counterpulsation (IABP) is an important adjunct to the treatment of profound cardiogenic shock (CS) with a widely used, nonpulsatile centrifugal pump (CP). In each of 18 anesthetized, open chest pigs, the outflow cannula of the CP was inserted in the aortic arch through the right external carotid artery, and the inflow cannula of the CP was placed in the left atrium. A 40 cc IABP was subsequently placed in the descending aorta through the left external carotid artery. CS was induced by occlusion of coronary arteries and the infusion of propranolol and crystalloid fluid. Mean aortic pressure, pulse pressure, aortic end diastolic pressure, left ventricular end diastolic pressure, right atrial pressure, and heart rate were monitored. Cardiac output and left anterior descending artery flow were measured with a transit time ultrasound flowmeter. During profound CS, life sustaining hemodynamics were maintained only with the support of the assist devices. Hemodynamic support with the CP was associated with a nearly nonpulsatile flow and a pulse pressure of 7 +/- 4 mm Hg, which increased to 33 +/- 10 mm Hg (p = 0.000) after combining the CP with the IABP. Compared with the hemodynamic support offered by the CP alone, addition of the IABP increased mean aortic pressure from 40 +/- 15 to 50 +/- 16 mm Hg (p = 0.000), cardiac output from 810 +/- 194 to 1,200 +/- 234 ml/min (p = 0.003), and left anterior descending artery flow from 26 +/- 10 to 39 +/- 14 ml/min (p = 0.001). In profound CS, mechanical support provided by a continuous flow CP is enhanced by the added pulsatility of the IABP.     

Energy equivalent pressure and total hemodynamic energy associated with the pressure-flow waveforms of a pediatric pulsatile ventricular assist device

A pulsatile pediatric ventricular assist device (VAD) with a dynamic stroke volume of approximately 12 ml was tested to quantify the effect of flowrate and systolic duration on pulsatility as quantified by the energy equivalent pressure (EEP), defined as the hemodynamic energy per unit volume of fluid pumped. The VAD was tested on a mock circulatory loop, adjusted to maintain a systemic arterial pressure of approximately 90/60 mm Hg (systolic/diastolic) and a mean of 75 mm Hg. The EEP was calculated for each beat for 1 minute at both the proximal end of the pump outlet cannula and at the distal end (arterial EEP). Nominal mean flowrates were 0.50, 0.75, 1.00, and 1.25 l/min. Systolic duration was set at either 230 or 400 milliseconds. With a rapid systolic ejection (230 milliseconds), the arterial EEP ranged from 5.58% to 8.41% relative to the mean arterial pressure. The highest EEP occurred at the lowest flowrate. With a slower (400 milliseconds) systolic ejection, the arterial EEP ranged from 2.33% to 4.20%. Hemodynamic energy loss in the outlet cannula was also quantified by the differential EEP and shown to increase markedly as systolic duration was decreased, but was relatively insensitive to mean flowrate.     

Eine elektromagnetische Stromuhr zur Messung des Coronarsinusausflusses

Zusammenfassung Es wird ein Meßkopf zur Messung des Coronarsinusausflusses bei geschlossenem Thorax beschrieben. Der Meßkopf arbeitet nach dem Prinzip der elektromagnetischen Stromuhr und hat alle Vorteile dieses Meßprinzipes. In zahlreichen Experimenten an Hunden hat das Gerät seine Brauchbarkeit bewiesen. Es werden Registrierbeispiele des Sinusausflusses, auch bei hoher zeitlicher Auflösung mitgeteilt.

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An instrument is described for the measurement of coronary sinus outflow. It consists of an electromagnetic flowmeter built into the end of a polyethylene cannula, which is placed in the coronary sinus. Through this cannula coronary sinus blood can be continuously drawn and thus the instrument has the advantage of measuring both flow and PO₂ or oxygen saturation simultaneously in closed chest animals. Two examples of flow records obtained using this instrument are included.

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Mit 3 Textabbildungen     

The dynamics of the coronary venous pressure in the dog

Summary The dynamics of the pressure in the great cardiac vein and coronary sinus was studied in 30 anaesthetized, artificially ventilated dogs. The pressure in the coronary venous system was found to be pulsatile and two positive pressure waves were distinguished. The a-wave, coinciding with the right atrial systole, appeared in the distal parts of the coronary sinus only, whereas the v-wave, concurring with the ventricular systole, was observed at all levels of the coronary venous system investigated, being most distinct in its proximal portions. The a-wave was accentuated during rapid atrial infusion which raised the right atrial pressure level. On the other hand, the v-wave was very markedly exaggerated following sympathetic stimulation and, particularly administration of norepinephrine (1 and 5 /kg i.v.), this concurring with the increase of ventricular contractile force. The amplitude of pressure pulsations rose, on the average, from 6.2–10.6 mm Hg following sympathetic stimulation, and from 7.7 to as much as 31 mm Hg with a 5 /kg dose of norepinephrine. The amplitude of pressure pulsations within the coronary sinus was also increased by papaverine (2.5 mg/kg i.v.) which elicited a marked augmentation of coronary blood flow without causing any significant rise of ventricular contractile force. The amplitude of pressure pulsations rose, on the average, from 8,8–13,7 mm Hg. Increasing the heart rate, over a range of 70 to 300 beats per minute, brought about a reduction of pulsations paralleling the reduction of ventricular contractile force despite the concomitant augmentation of coronary blood flow. It is concluded that the pulsations of the coronary venous pressure are due to mechanical effects of ventricular contractions mainly, which acting as a muscle-pump promote the emptying of the coronary veins. The actual amplitude of pressure pulsations is determined by the force of ventricular contractions, and by the state of filling of the coronary veins correlated with the level of coronary blood flow.This study was performed during the tenure of a stipend from the Ministry of Health of the German Democratic Republic.     

Observations on coronary collateral communications and the control of flow in the coronary circulation of the dog

1. Pressure was measured in the small arterial anastomosing branches of the coronary vascular network. The mean value was 30 mm Hg not significantly different from the mean value of 33 mm Hg for peripheral coronary pressure measured distal to a ligature on the anterior descending branch of the left coronary artery. Evidence was adduced to show that either the anterior descending or the circumflex artery had the capacity to maintain network pressure at levels adequate for tissue perfusion.2. The network has both capacity and compliance. Filling of the network compliance during systole probably accounts for the systolic phase of coronary flow. Flow through the microcirculation is probably entirely diastolic, the combined compliance of the aorta and large vessels together with the network provides the necessary reservoir, the potential energy indicated by diastolic pressure provides the perfusion pressure head.3. Resistance of vessels between the aorta and network cannula (pre-net) was approximately double that of the microcirculation (post-net). The smaller pre-network vessels are of the order 70 mum in diameter. Both pre- and post-network vessels are vaso-active and respond similarly to adrenaline and haemorrhage.     

Sites of cholinergic vasoconstriction in trout gills.

Sites of cholinergic vasoconstriction were investigated in isolated saline-perfused holobranchs of trout (Salmo gairdneri and S. trutta). Acetylcholine (ACh) always increased overall branchial vascular resistance (BVR) and, in addition, decreased the proportion of the total inflow appearing at the outflow cannula from the efferent arch artery. Since this was observed in both constant pressure and constant flow situations, it was concluded that ACh exerted most of its effect at a site downstream from the secondary lamellae, probably at the bases of the efferent filament arteries. Prussian blue dye injections indicated that, in addition, ACh caused a marked reduction in flow to the distal halves of the filaments and that flow within the proximal secondary lamellae was restricted during ACh administration to the inner and outer marginal channels of the lamellae. The results are discussed in terms of recent findings concerning the vascular anatomy of teleost gills.     

A performance evaluation of eight geometrically different 10 Fr pediatric arterial cannulae under pulsatile and nonpulsatile perfusion conditions in an infant cardiopulmonary bypass model

This investigation compared pressure drops and surplus hemodynamic energy (SHE) levels in eight commercially available pediatric aortic cannulae (10 Fr) with different geometries during pulsatile and nonpulsatile perfusion conditions in an in vitro infant model of cardiopulmonary bypass. For each trial, the cannula was placed at the distal end of the arterial line, and the insertion tip was fixed to the inlet of the simulated patient. The pseudo patient was subjected to seven pump flow rates ranging from 400 to 1000 ml/min (at 100 ml/min increments), and the mean arterial pressure was set at a constant 40 mm Hg via Hoffman clamp. Of the eight cannulae, the Surgimedics and THI models had significantly larger pressure drops (48.8 +/- 0.3 mm Hg and 48.3 +/- 1.4 mm Hg, respectively; 600 ml/min pulsatile) compared with the RMI cannula (27.6 +/- 1.2 mm Hg; 600 ml/min pulsatile), which created, on average, half of the pressure drop seen in the poorest performing cannulae. When perfusion mode was switched from nonpulsatile to pulsatile, there was a 7-9 fold increase in delivery of SHE recorded at both the pre- and postcannulae sites, regardless of which cannula was being tested. Despite being classified under the same size (10 Fr), these eight cannulae were found to vary considerably in length, inner diameter, and geometrical design. The results suggest that these differences can have a significant impact on pressure drops, as well as generation and delivery of SHE. Furthermore, it was found that pulsatile perfusion produced more "extra" hemodynamic energy when compared with nonpulsatile perfusion, regardless of cannula model.     

Effects of acute systemic anoxia on the coronary sinus pressure and flow in the dog

Summary The effects of acute systemic anoxia on blood pressure and flow in the coronary sinus were investigated in 23 anaesthetized open-chest dogs. Severe anoxia, produced by inhalation of 100% nitrogen over a period of 1.5 to 2 min, elicited regularly a progressive rise in amplitude of pressure pulsations within the coronary sinus. It amounted at the height of anoxia to 37.3 mm Hg, on the average, as compared to 5.3 mm Hg under control conditions (+600%). Similarly, the mean coronary sinus pressure rose progressively during anoxia. The rise in coronary sinus pressure paralleled the increase of coronary sinus outflow and ventricular contractile force. It evidently preceded the onset of anoxic bradycardia. Bilateral vagotomy, which caused attenuation or abolition of bradycardia, reduced only moderately anoxic rise in coronary sinus pressure. It is concluded that the rise in the amplitude of pressure pulsations in the coronary sinus, encountered in acute systemic anoxia, is due to the increase of ventricular contractile force, and, particularly, to the improved filling of the coronary veins, correlated with the augmentation of coronary blood flow. Anoxic bradycardia is an additional factor contributing to the increased venous filling by prolonging the duration of the filling period.Death by accident in March 23, 1966.This study was performed during the tenure of a stipend from the Ministry of Health of the German Democratic Republic. Present address: Department of Physiology, Karl-Marx-University, Leipzig.     

Changes in the cardiac output and general peripheral resistance after obstruction of a coronary artery

Summary The left subclavicular, both carotid and femoral arteries were shunted; then the brachiocephalic artery and aorta were obstructed, distal to the origin of the left subclavicular artery. The output of the left ventricle, excluding that portion of it which flows into the coronary arteries, entered the rotameter through theleft subclavicular artery and flowed into the distal sections of carotid arteries and the proximal sections of the femoral artery. The average blood pressure in the system was measured by an electric manometer. From these data, general peripheral resistance could be estimated according to the data obtained. An average blood pressure of 80–100 mm Hg is the best at which to study the changes of hemodynamic indices occurring after obstruction of the coronary artery.(Presented by V.V. Parin, Active Member of the AMN SSSR) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 50, No. 7, pp. 27–33, July, 1960     

First use of the Cancion cardiac recovery system in a human

Animal studies have shown clearly that a peripheral circulatory support system can effectively unload the left ventricle. We report here the first implantation of one such system (Cancion, Orqis Medical, Lake Forest, CA) in a human. The Cancion system consists of a centrifugal pump connected to the circulation via a graft cannula anastomosed to the left axillary artery and a percutaneous cannula placed into the left common femoral artery. Flow is initiated from the femoral to the axillary artery. The system was implanted in a 62-year-old man with ischemic cardiomyopathy suffering from decompensation whose condition had not improved with catecholamine therapy. The Cancion system supported the patient for 3 days, after which it was electively explanted. During the support period, pulmonary capillary wedge pressure dramatically decreased from 28 to 9 mm Hg, left ventricular diastolic dimension decreased from 6.78 to 6.16 cm, creatinine levels decreased from 1.9 to 0.9 mg/dl, cardiac index improved from 1.5 to 2.7 L/min, and ejection fraction improved from 25 to 35%. Together, our data indicate that the Cancion system quickly and effectively improved the patient's hemodynamics. This suggests that the device may one day become a short-term alternative to high dose inotrope therapy and that its application may delay the need for more invasive forms of mechanical circulatory support.     

A possible relationship between reliability of thoracic outlet syndrome diagnostic testing and the position of the axillary artery

Purpose

Publications describe variable spatial relationships between the axillary artery and brachial plexus whereby the axillary artery may be compressed by the median nerve roots when the upper extremity is hyper-abducted. The purpose of this study is to quantify the frequency of variant positioning of the axillary artery with respect to the brachial plexus, describe and quantify the lengths of the median nerve roots, and evaluate intra-arterial pressure in axillary arteries of normal and variant cadavers when the upper extremity is hyper-abducted.

Methods

Three-hundred and thirty-eight cadaveric axillae were dissected to evaluate the spatial relationship between axillary artery and the median nerve roots. Three-hundred and twelve cadaveric axillae were dissected to evaluate the lengths of the median nerve roots. Twelve cadavers were selected for evaluation of the intra-arterial pressure during a hyper-abduction procedure.

Results

The axillary artery was positioned anterior to the median nerve roots in 6.8% of axillae and positioned posterior to the median nerve roots in 93.2% of axillae. An experimental cohort, possessing a classic relationship between axillary artery and median nerve roots and a proximal union of the median nerve roots, showed an increase in intra-arterial pressure during hyper-abduction test. All other experimental cohorts exhibited no change in intra-arterial pressure.

Conclusions

These findings suggest that the median nerve roots are capable of compressing the axillary artery when the upper extremity is hyper-abducted, the axillary artery is positioned posterior to the median nerve roots, and the patient possesses a more proximal convergence of the median nerve roots.     

Total anomalous origin of the coronary circulation from the right pulmonary artery

Origin of both coronary arteries from a branch of the pulmonary artery is rare and has not been reported as a cause of sudden unexpected death. We report autopsy findings of a 14-day male infant in previously good health who died suddenly. From the proximal right pulmonary artery arose a single coronary artery, which branched into the right and left main coronary arteries. The right proximal coronary artery coursed between the aorta and pulmonary trunk, and the left main traveled along the anterior proximal aorta. The distal course of the coronary circulation was normal. There was concentric subendocardial healing myocardial infarction. No other congenital anomalies were identified. Total anomalous origin of the coronary arteries from the pulmonary trunk or artery should be considered in cases of sudden unexpected death in infants.     

Die extravasale Komponente des Coronarwiderstandes mit steigendem linksventrikulären Druck

Summary In experiments on anaesthetized dogs the arterial blood pressure and the left ventricular pressure were enhanced by intraarterial blood transfusion. The circumflex branch of the left coronary artery was perfused by constant blood pressure at 65, 100 or 200 mm Hg. After elimination of the sinus node the heart rate was kept constant at 150 beats per minute by electrical stimulation of the right auricle. The metabolically regulated component of coronary resistance of the circumflex branch was kept constant by a maximal pharmacological dilatation. On this condition the coronary blood flow decreases with increasing left intraventricular systolic pressure. The coronary resistance increases. The increasing coronary resistance with increasing intraventricular blood pressure is caused by an enhancement of the extravascular component because the perfusion pressure and hematocrit were constant, and the coronary vessel maximal dilated. The rise of coronary resistance with increasing intraventricular blood pressure depends on the height of perfusion pressure. Low perfusion pressure is combined with a marked increase, while the increase is small in the experiments with high perfusion pressure. The pathophysiological significance of the results has been discussed.

     

Blood vessels of the sinus tarsi and the sinus tarsi syndrome

This study describes the arterial and venous blood vessels in the sinus tarsi of a series of nine anatomical specimens and in a traumatically amputated leg, studied by arteriography. The sinus tarsi artery was formed in all cases from anastomoses between various arteries of the lateral region of the foot. These usually included the anterior lateral malleolar, and proximal lateral tarsal arteries; in 70% there was a branch from the distal lateral tarsal artery, and in 30% a branch from the peroneal artery. In all cases, ther were anastomoses within the sinus tarsi between the sinus tarsi artery and the canalis tarsi artery, derived from the posterior tibial artery. Whatever its origins, the sinus tarsi artery was the principal supplier of intrasinusal structures and of the talus. There was a large venous plexus in the sinus tarsi, which drained particularly the venous outflow from the talus and the anterior part of the capsule of the posterior talocalcaneal joint to the lateral and medial venous systems of the foot. Posttraumatic fibrotic changes in the wall and surrounding tissue of the veins, causing disturbance of venous outflow and increased intrasinusal pressure, are proposed by the authors as one possible factor in the pathogenesis of the sinus tarsi syndrome. Clin. Anat. 10:173–182, 1997. © 1997 Wiley-Liss, Inc.     

Hemodynamic effects of a new percutaneous circulatory support device in a left ventricular failure model

We have tested a new percutaneous circulatory support device in seven anesthetized calves with induced left ventricular failure. The device is based on a flexible catheter with a foldable propeller and cage at the distal end. The rotation of the propeller (1,000-15,000 rpm) is transmitted from a drive unit at the proximal end to the propeller by way of a rotating wire inside the catheter. This also contains an umbrella-like mechanism to open the pump head from the folded (diameter 4.6 mm) to the active position. The rotation of the propeller creates a pressure drop in front of the propeller and a pressure rise behind. Heart failure was induced with metoprolol and verapamil in combination with a VVI pacemaker to create a left atrial pressure greater than 20 mm Hg. A centrifugal pump was used to bypass the right ventricle and to ensure a sufficient filling of the left ventricle. After baseline recordings, the pump was run at 14,000 rpm, and the hemodynamic response was compared with the baseline. A 24 +/- 10 mm Hg pressure gradient was generated across the pump, resulting in a drop in the right carotid artery mean pressure from 80 +/- 11 to 71 +/- 13 mm Hg (p = 0.008) and a drop in the left ventricular systolic pressure from 109 +/- 17 to 100 +/- 19 mm Hg (p = 0.004). The pressure in the left atrium decreased from 25 +/- 3 to 20 +/- 5 mm Hg (p = 0.008). The mean femoral pressure increased from 78 +/- 10 to 95 +/- 20 mm Hg (p = 0.005). A moderate reduction in the right carotid flow was observed (15%, p = 0.029), whereas no significant changes were found in the coronary flow, the flow in the right femoral artery, or in the left kidney. The device showed a significant unloading of the left ventricle and an increased perfusion pressure for the lower part of the body. The moderate changes in flow were probably caused by still active autoregulation, and this needs to be tested with more pronounced circulatory failure.     

Localized atresia of the coronary sinus a short distance proximal to its ostium.

Atresia of the ostium of the coronary sinus (CS) is a well-recognized abnormality. We report the incidental finding of atresia of the distal portion of the CS, a short distance proximal to its ostium in a 39-week-old neonate, which, as far as we are aware, has not been previously reported.     

Effects of graded pulsatile pressure on the reflex vasomotor responses elicited by changes of mean pressure in the perfused carotid sinus-aortic arch regions of the dog

1. In the anaesthetized dog, the carotid sinuses and aortic arch were isolated from the circulation and separately perfused with blood by a method which enabled the mean pressure, pulse pressure and pulse frequency to be varied independently in each vasosensory area. The systemic circulation was perfused at constant blood flow by means of a pump and the systemic venous blood was oxygenated by an extracorporeal isolated pump-perfused donor lung preparation.2. We have confirmed our previous observations that under steadystate conditions the vasomotor responses elicited reflexly by changes in mean carotid sinus pressure are modified by alterations in carotid sinus pulse pressure, whereas those evoked by changes of mean aortic arch pressure are only weakly affected by modifications of aortic pulse pressure.3. When the carotid sinus and aortic arch regions are perfused in combination at constant pulse frequency (110 c/min), the relationship between mean carotid sinus-aortic arch pressure and systemic arterial perfusion pressure is dependent on the size of the pulse pressure.4. Increasing the pulse pressure alters the curve relating the mean carotid sinus-aortic arch pressure to systemic arterial perfusion pressure in such a way that the perfusion pressure is lower at a given carotid sinus-aortic arch pressure within the range 80-150 mm Hg. The larger the pulse pressure, up to about 60 mm Hg, the greater the fall in systemic arterial perfusion pressure. Above a mean carotid sinus-aortic arch pressure of about 150 mm Hg, alterations of pulse pressure have little effect.5. There is a family of curves representing the relation between mean carotid sinus-aortic arch pressure and systemic vascular resistance, depending on the pulse pressure.     

Acute myocardial infarction due to an unruptured sinus of Valsalva aneurysm in a patient with Behçet's syndrome

This report describes the case of a 45-year-old Korean female who had suffered from Behçet''s syndrome for two years with a huge, unruptured aneurysm originating from the left coronary sinus. The aneurysm had caused myocardial and aortic insufficiency by compressing the proximal left anterior descending coronary artery. The orifice of the aneurysm was at the left coronary sinus, about 5mm from the left main coronary ostium, and it was filled with organized thrombi. Surgical repair was performed by closing the entrance of the aneurysm with a Dacron patch and by implementing aortic valve repair and coronary artery bypass grafting. The patient''s coronary flow was restored postoperatively, and all anginal symptoms disappeared.     

Flow and O2 content of the blood return from the myocardium to the coronary sinus and other cardiac vessels

Summary In the anesthetized dog with by-pass of the right ventricle or with total by-pass of the heart, quantitative data were obtained on the distribution of the myocardial venous blood between the coronary sinus and other cardiac vessels and on the O₂ content of these two blood fractions. The results of the right heart by-pass experiments confirm that the 60–70% of the coronary venous blood returns from coronary sinus. The progressive rise of the right systolic ventricular pressure increases the amount of blood returning from coronary sinus.The O₂ content of coronary sinus blood is constantly lower than the O₂ content of the extracoronary venous blood at all the values of systolic pressure in the right ventricle. The experiments with the total by-pass of the heart show that the distribution of venous blood between the coronary sinus and extracoronary channels and the difference in O₂ content between the two coronary bloods do not seem practically influenced by the fact that the two ventricles are working or not.These results could be explained: first by the fact that in the normal circulatory conditions the O₂ consumption of the right ventricle is lower than that of the left ventricle; second by an increased velocity of the blood travelling through the right coronary artery; third there is a direct arterial flow to the right ventricle through the arterio-luminals and arterio-sinusoidals. However the above mentioned hypothesis are not experimentally demonstrated and then further investigations are needed to throw better light on this problem.With 3 Figures in the Text     

Pressure drops in cannulas for hemodialysis.

Pressure drops in cannulas for hemodialysis have been measured in vitro in both flow directions for five different viscosities and up to 600 mL/min flow Cannula dimensions were 15, 16 and 17 gauge and 15, 20 and 25 mm nominal length. The measurements were taken at room temperature with glycerin solutions as test fluid. RESULTS: The pressure drops can be described by a second order function but not by the Hagen-Poiseuille law even when corrected for inlet and outlet effects as described by Bernoulli's law. Pressure drops depend on flow direction. Back-eyes and cannula tips have no influence on the pressure drop. Pressure drops and especially flow direction asymmetry are influenced by the hydraulic design of the connection piece between cannula and tubing. The results can be used for prediction of pressure drops in cannulas allowing better use of pressures already measured in the extracorporeal circuit of hemodialysis machines.