Catheter-tip Manometer Research Articles

The mechanical properties of exposed human common carotid arteries in vivo.

In exposed common carotid arteries of 15 patients (36-74 years) undergoing neck surgery, the intra-arterial pressure (P) was recorded by means of a catheter-tip manometer and, at the same site, the external diameter (D) by means of a contact-free photoelectric device. On the average, the pulsatile diameter changes were 5.6% of the end-diastolic diameter at pulse pressures of about 50 mm Hg. Due to viscoelasticity, the P-D diagrams exhibited hysteresis loops. Using the criterion of loop elimination, an iterative procedure was applied which permitted, by the use of an appropriate computer program, the separation of the purely elastic and the purely viscous components of the P-D relationships. In all cases, the purely elastic P-D curves markedly deviated from linearity. The tangential elastic modulus (Et) and the pulse wave velocity (c) calculated from these curves were normalized by dividing these quantities by the respective end-diastolic values and plotted against the normalized external diameters. During each pulse cycle, Et increased, with increasing diameter, by a factor between 1.2 and 3.5, while c increased by a factor between 1.1 and 1.9 with reference to the respective end-diastolic values.

Ventricular function at rest, during leg raising and physical exercise before and after aortocoronary bypass surgery

In nine patients with coronary heart disease contractility indexes during isovolumic contraction and during the ejection phase were measured simultaneously, using an angiographic catheter-tip manometer. Regional wall motion at rest, after leg raising and during physical exercise (bicycle ergometer) was analyzed using the hemiaxis method. Five weeks after aortocoronary bypass surgery these examinations were repeated. Preoperatively left ventricular end-diastolic pressure increased from 21 to 37 mm Hg after leg raising. The velocity of mean circumferential fiber shortening (VCF) and of regional shortening in the anterior wall decreased significantly. All patients discontinued physical exercise due to angina pectoris. Left ventricular end-diastolic pressure increased from 21 to 39 mm Hg during exercise. Large hypokinetic and akinetic areas developed, especially in the anterior wall. Velocity of fiber shortening of the anterior wall decreased from 1.43 to 0.76/sec. End-diastolic volume remained unchanged, but end-systolic volume increased significantly. In six patients with patent grafts surgery had a beneficial effect. Angiograms at rest revealed no significant postoperative changes; however, after leg raising and physical exercise, ventricular function was greatly improved over the preoperative performance. Velocity of fiber shortening in the anterior wall increased significantly from 0.76 to 2.56/sec, mean VCF from 1.11 to 2.12 circumferences/sec, maximal rate of rise of left ventricular pressure from 2,302 to 4,280 mm Hg/sec and peak velocity of contractile elements (Vpm) from 27.8 to 55.7/sec. The mean functional improvement in individual wall segments was 500 percent. Ejection fraction increased from 54 percent to 76 percent. End-diastolic volume remained unchanged while end-systolic volume decreased from 67 to 33 ml/1.73 m 2 ( P < 0.002). In three patients occlusion of the bypass graft or myocardial infarction occurred intraoperatively. Their postoperative findings at rest and during exercise were unchanged from the preoperative values. After successful bypass surgery ventricular function at rest did not change, but during exercise, a marked improvement in overall and in regional ventricular function was found.

Analysis of left ventricular behaviour in diastole by means of finite element method.

The human left ventricle in diastole can be modelled as a passive structure with incremental internal pressure change being considered as the load. Recent developments in engineering stress analysis provide techniques for predicting the behaviour of structures with complex geometry and material properties, as is the case with the left ventricle. That which is most appropriate is the finite element method which requires the use of a large digital computer. The ventricles of 2 patients have been studied during diastole, the geometries having been derived from cineangiographic data (biplane), and the pressure by means of catheter-tip manometers. Various descriptions of myocardial stress/strain relations have been assumed and applied to the left ventricular wall in order to obtain the best match between the calculated and observed deformation patterns. The manner in which the value and distribution of stiffness in the left ventricle influences the shape change can therefore be determined, and possible clinical implications deduced.

A model of graded ischemia in the isolated perfused rat heart.

Insertion of a flow pump into the Langendorff retrograde perfusion apparatus has permitted the production of stable, graded ischemia in hearts whose hemodynamic and metabolic response may be evaluated. Ventricular pressures were monitored with a modified balloon and catheter-tip manometer system, and oxygen consumption , lactate and glucose metabolism, and tissue high-energy phosphate stores measured. A 15-min stabilization period in 56 paced hearts was followed by 15 min of either full, 40, 30, 20, or 10% coronary flow, after which the ventricular tissue was freeze-clamped for tissue assay. Tissue creatine phosphate fell progressively from 23.7 in full flow hearts to 9.9 mumol/g dry wt after 90% reduction in flow. This was accompanied by a graded reduction in ATP from 20.3 to 14.0 mumol/g dry wt and a rise in AMP from 1.1 to 2.6 mumol/g dry wt. Tissue lactate rose progressively from 22.3 to 60.1 mumol/g dry wt. Hemodynamic function correlated with coronary flow. This preparation offers an opportunity to study pharmacological and metabolic interventions in ischemic heart disease.

Recording of ventricular pressure by conventional catheter manometer systems. I. Minimal requirements of blood pressure recording systems and estimation of frequency response characteristics

Parallel recordings of pressure pulses by conventional catheter manometer systems and catheter tip manometer demonstrate severe errors in the peak velocity of pressure rise estimated by conventional systems. This fact is due to inadequate dynamic response characteristics of conventional systems in relation to the frequency content of pressure curves. During cardiac rest the error in dp/dt max is less than 10% if the frequency response of the recording system is uniform up to 10 Hz, the corresponding value under maximal cardiac stimulation is about 40 Hz. This is equal to the first 10 harmonics of heart rate. The examination of left and right ventricular pressure curves leads to similar results. The experimental determination of dynamic response characteristics of cathermanometer systems requires a test system producing suitable sinus or step functions, parallel high fidelity recording of pressure functions to be recommended. A simple test station is described. Examinations of temperature influence on catheter material and resulting changes in dynamic response characteristics were carried out. The incubation of catheters at the temperature of 37 degrees C is indispensable. A new diagram for simplifying the interpretation of results is described. Other publications are discussed in viewpoint of employed techniques and representation of results.

Continuous recording of local myocardial function in normal and ischemic myocardium.

Experiments in anaesthetized open chest dogs are described in which intramyocardial pressure was determined by two methods, both suitable for long time experiments. By means of a Fogarty catheter in connection with a normal transducer the intramyocardial pressure can be measured. With this method the pressure gradient from epicardial to endocardial muscle layers is demonstrated. Insertion of catheter tip manometers leads only to small trauma of the myocardium. This method allows the determination of systolic and enddiastolic tissue pressure together with the dp/dtmax and dp/dtmin. Measurements were performed in normal and in ischemic areas of the myocardium. In the ischemic parts of the myocardium all parameters descline, while in the normal, non ischemic areas the parameters increase, thus demonstrating overactivity, which compensates for the loss of myocardial function in the ischemic parts. The overall function of the heart as a pump remains nearly unaffected. On release of the coronary ligature the negative changes in the ischemic myocardium are rapidly restored. During the phase of reactive hyperemia the parameters measured in the ischemic area even increase above the control values.

Time relation between apex cardiogram and left ventricular events using simultaneous high-fidelity tracings in man.

In 10 patients without left heart valvular disease and having normal function of the left ventricle, the left ventricular apex cardiogram with its first derivative (dA/dt), left ventricular pressure with its first derivative (dP/dt), aortic pressure, electrocardiogram, and phonocardiogram were reocrded simultaneously during cardiac catheterization. The apex cardiographic tracings were obtained by means of a transducer with infinite time constant and very high resonant frequency and the LV and aortic pressures with catheter tip-manometers. The onset of the systolic rise of apex cardiographic and LV pressures were found to occur almost simultaneously with the upstroke of LV pressure, preceding that of the apex cardiogram by only 2 +/- 4 ms (mean +/- 1 SD). The summit of the systolic upstroke of the apex cardiogram (called E-point) occurred 37 +/- 9 ms after opening of the aortic valve and 41 +/- 9 ms after peak dP/dt. The peak of dA/dt preceded peak dP/dt by 10 +/- 4 ms. The protodiastolic nadir of the apex cardiogram (called-O-point) occurred slightly earlier (19 +/- 16 ms) than the nadir of the LV pressure curve, with considerable variation. In conclusion, this study using external and internal transducers with similar characteristics gives a new definition of the time relation between the externally recorded apex cardiogram and the haemodynamic events within the left heart in human subjects with normal left ventricular function.

Quantitative evaluation of postectopic beats in the normal and failing human heart using indices derived from catheter-tip manometer readings.

Postextrasystolic potentiation was studied by means of a catheter-tip manometer in patients with and without cardiomyopathy. The results imply that the enhancement of the left ventricular contraction is increased in patients with cardiomyopathy.

Limitation of correction of frequency dependent artefact in pressure recordings using harmonic analysis.

Frequency dependent phase and amplitude distortion may theoretically be minimized using correction formulae derived from a model which assumes that water-filled catheter-manometer systems are analogous to an oscillating mass attached to a spring and damping pot. This study defines the practical limits of this correction technique using harmonic analysis of simultaneously recorded water-filled and catheter-tip manometer systems. Some improvement was obtained in tracings recorded with underdamped, high frequency response systems. In no case were exact duplications of the catheter-tip tracings obtained. Divergence of measured vitro frequency response from actual in vivo frequency response was one source of these discrepancies. Loose coupling of the components of the system also changed the behavior from that of the assumed simple mechanical model and at times prevented adequate correction. Catheter-tip manometers, in spite of their expense and relative fragility, still appear to be the best means at present of obtaining accurate pressure tracings, particularly at high heart rates or where time derivatives are to be computed.

Frequency Content of Intravascular and Intracardiac Pressures and Their Time Derivatives

The purpose of this study was to determine the frequency content of intravascular pressures and their time derivatives. Pressures, recorded using catheter-tip manometers in patients undergoing diagnostic cardiac catheterization, were amplified, filtered (100 Hz) to minimize aliasing errors, and then converted to digital format at 200 samples/sec. After examination of the waveform to exclude obvious artefact, it was analyzed using a Fourier transform and then resynthesized using a decreasing number of harmonics. Peak dp/dt of both the original and resynthesized waveforms was computed until marked differences were observed.

Cinefluorographic study of the aortic ball-cage prosthetic valve: Phonocardiographic, hemodynamic and angiographic correlates

Cinefluorographic evaluation of the Starr-Edwards aortic prosthetic valve (model 2320) was performed in 41 patients. The aortic pressure pulse, obtained with a catheter-tip manometer, the electrocardiogram and phonocardiogram were recorded simultaneously on cine film and photographic paper. The patients were classified into three groups on the basis of the behavior of the poppet during ejection. In Group I (20 patients) the poppet remained in a relatively fixed position at the apex of the cage throughout the ejection period. Ascent of the poppet at the beginning of ejection was associated with an opening sound and occurred simultaneously with the increase In aortic pressure. An ejection click occurred on Impact of the poppet against the apex of the cage. Descent of the poppet at the end of ejection started 50 msec before the incisura, at a time when supraaortic angiograms demonstrated reflux of contrast material into the left ventricle. Final closure occurred on inscription of the incisura and was associated with a closure sound. In Group II (11 patients) the poppet bounded away from the apex of the cage early during the ejection period and promptly returned to the apex for the remainder of the period. The double impact of the poppet early during ejection was associated with a double ejection click. In Group III (10 patients) premature partial closure of the valve occurred during ejection. After striking the apex of the cage during early ejection, the poppet descended almost one half the distance toward the base of the valve and remained in a relatively fixed, partially closed position during the rest of the ejection period. In this group, unlike Groups I and II, the high frequency component of the closure sound was almost half the amplitude of the ejection click. In three patients a slight tilt of the prosthetic valve in relation to the ascending aorta was noted. This tilt was not observed in Groups I and II. The behavior of the poppet in the three groups can be explained by the hydrodynamic principle of resistance of a solid body in a fluid stream. The angiographic findings indicate that in all patients final closure of the prosthetic valve was due to backward aortic flow.

Long sheath technique for introduction of catheter tip manometer or endomyocardial bioptome into left or right heart.

Long sheath technique for introduction of catheter tip manometer or endomyocardial bioptome into left or right heart.

CHANGES IN PRESSURE WAVE TRANSMISSION ALONG HUMAN AORTA WITH AGE AND ARTERIAL DISEASE

Top of pageAbstract Previous studies have shown that in children the amplitude of pressure waves increases progressively along the aorta and a diastolic wave appears in peripheral arteries. These alterations become less with age or arterial disease so that the wave is transmitted virtually unchanged in older patients (pts.) with arterial degenerative disease. Pressures were measured in aortic root, aortic arch, and either iliac or brachial arteries during diagnostic catheterization in 198 pts., aged 1 day to 70 yrs. There was no significant difference in amplification for pts. with normal arteries and normal aortic valves (81), aortic stenosis (48), or aortic insufficiency (9). Amplification averaged 1.56±.26 for normal pts. aged 0-19 yrs., 1.23±.19 between 20-39, and 1.17±.13 over 40. For each age range, pts. with arterial disease had a lower mean amplification, but with considerable overlap after 40 yrs. Slightly improved separation of normal and abnormal was obtained using catheter-tip manometers, Fourier analysis and amplification of individual harmonic terms. Pulsewave velocity, using foot-to-foot transmission time and measured catheter lengths from aortic arch, averaged 455±78 cm/sec in 50 normals, 464±82 in 39 with aortic stenosis, and 622±245 in 18 with arterial disease. (Supported by NIH-HL14207-03).

A technique for trans-septal left heart catheterization with a catheter tip manometer

A percutaneous trans-septal method of left ventricular catheterization with a Statham SF-1 catheter tip manometer is described. To make the procedure relatively safe, a special left heart catheter introducer (inserted via the right subclavian vein) has been devised.

Determination of ventricular pressure velocity curves with special reference to the end-diastolic pressure

The left ventricular pressure of anaesthetized cats was measured with a catheter-tip manometer. By using an analog computer, the quotients $$\frac{{{{dp} \mathord{\left/ {\vphantom {{dp} {dt}}} \right. \kern-\nulldelimiterspace} {dt}}}}{p}$$ and $$\frac{{{{dp} \mathord{\left/ {\vphantom {{dp} {dt}}} \right. \kern-\nulldelimiterspace} {dt}}}}{{p - edp}}$$ which are accepted to be directly proportional to the velocity of shortening of the contractile elements, were calculated and plotted versus pressure on axy-oscillograph in order to obtain instantaneous pressure-velocity curves. Pressure-velocity curves are nearly linear in their descending limb only when the total ventricular pressure and not the developed pressure is used for the measurement. When instead of the absolute pressure one uses the developed pressure for the calculation of velocity of shortening, the curves rise with a steep slope. The curves are similar to the force-velocity curves obtained with isolated papillary muscles, though a graphic calculation of velocity at zero pressure or enddiastolic pressure is not exactly possible.

Effect of pacing-induced tachycardia and myocardial ischemia on ventricular pressure-velocity relationships in man.

Ventricular function was evaluated in 18 patients prior to left ventriculography and selective coronary arteriography. Simultaneous left ventricular pressure (catheter-tip manometer) and dP/dt were recorded at resting heart rates and during tachycardia induced by right atrial pacing. Pressure-velocity curves were constructed from which V max and maximum measured contractile element velocity (max V CE ) were obtained. V max and max V CE initially increased with pacing-induced tachycardia in 17 of the 18 patients. Eight patients developed evidence of myocardial ischemia during atrial pacing. During the period of myocardial ischemia there was a decrease in V max and max V CE in all eight patients despite constant or increasing heart rate. In the 10 patients who did not develop evidence of myocardial ischemia with pacing-induced tachycardia, V max and max V CE continued to increase or remained constant with increasing rate. Peak left ventricular dP/dt increased coincident with the onset of myocardial ischemia in six of eight patients despite a fall in V max and max V CE in all eight patients during the ischemic period. A highly significant difference was demonstrated between V max values of patients with normal ejection fractions and patients with low ejection fractions, both at rest and during pacing-induced tachycardia.

Atrial transmural pressures during experimental pericardial tamponade.

To elucidate the mechanism responsible for the occurrence of negative transmural atrial pressures in pericardial tamponade, saline or air was progressively injected into the pericardial sac. In 14 anesthetized, open-chest dogs, left atrial (LA), left ventricular (LV), and pericardial pressures (PP) were measured with catheter tip manometers. In beating and fibrillated hearts, measurements were carried out at normovolemia, hypovolemia and hypervolemia. Transmural atrial pressure (TAP = LA - PP) became negative when the PP reached 130 mm H 2 O whether the heart was beating or not. In normovolemia the relation between TAP and PP was: TAP (mm H 2 O) = 38.1--0.237PP--0.00042PP 2 . In anesthetized, closed-chest dogs, air inflation of pleural space produced pressures around the heart similar to those obtained in pericardial tamponade. With such pneumothorax, no negative TAP occurred either with beating or quiescent hearts. It is hypothesized that pericardial filling stiffens the pliable structures surrounding the heart and thereby diminishes the collapsibility of the atrial walls which form the inner part of the pericardial sac. Veins entering the atria through the filled pericardial sac are held open like the hole in an inflated inner tube. Through these mechanisms some cardiac filling is assured even with marked pericardial tamponade.

Catheter-tip manometer for measuring blood pressure during g changes.

Catheter-tip manometer for measuring blood pressure during g changes.