Stroke volume and systolic time intervals: Beat-to-beat comparison between echocardiography and ambulatory impedance cardiography in supine and tilted positions

The aim of the study was to compare stroke volume (SV), ejection time (ET) and pre-ejection period (PEP) measurements obtained using a central haemodynamics ambulatory monitoring device based on impedance cardiography (ICG), in supine and tilted positions (60°), with pulsed Doppler echocardiography as a noninvasive reference method. The Holter-type ICG device was used for off-line, beat-to-beat, automatic determination of SV, ET and PEP. ICG data were compared with those obtained simultaneously using pulsed Doppler echocardiography in the ascending aorta from a suprasternal projection, 1 min before and 10 min after tilting. The tests were performed in 13 young, healthy subjects (six men and seven women, aged 23–33 years). Linear regression between the measured values obtained for all subjects was described by the following formulas: SV_icg=13.9+0.813*SV_echo (r=0.857 SEE=9.03, n=496), ET_icg=16.8+0.987*ET_echo (r=0.841, SEE=21.3, n=496), PEP_icg=22.8+0/890*PEP_echo (r=0.727, SEE=14.6, n=496). The data showed that ambulatory impedance cardiography gives useful absolute values of SV and systolic time intervals measured in supine and tilted positions.     

Doppler measurement of cardiac output across prosthetic mitral valves

Summary In 46 patients with a normal functioning mitral valve prosthesis (15 St. Jude, 19 Medtronic Hall, 12 Hancock) cardiac output was measured by pulsed Doppler echocardiography across the valve prosthesis. Simultaneously cardiac output was determined by thermodilution or pulsed Doppler echocardiography in the left ventricular outflow tract (2.8 l/min–9.5 l/min). The prosthetic valve area was calculated using the pressure half-time method. Cardiac output was calculated by multiplying time-velocity integrals with the mitral valve area. Cardiac output measurements across the mitral prosthesis correlated significantly with thermodilution (r=0.96, SEE=0.400 l/min) and pulsed Doppler echocardiography flow measurements in the left ventricular outflow tract (r=0.82, SEE=0.679 l/min). The mean percent error of the Doppler transmitral flow measurement was 10.8%. Doppler transmitral flow underestimated cardiac output values of more than 6.5 l/min in 6 of 7 patients. Cardiac output measurements across Hancock (SEE=0.473 l/min) and St. Jude prostheses (SEE=0.538 l/min) were more accurate than across Medtronic Hall prostheses (SEE=0.847 l/ min).Cardiac output can be calculated by pulsed Doppler echocardiography across normal functioning mitral prostheses. Due to the different flow dynamics the accuracy of cardiac output measurement depends on the prosthetic valve type. Reliable measurements of cardiac output can be performed across Hancock and St. Jude prostheses only. This method is limited in volume flow measurements across Medtronic Hall prostheses.     

A bioenergetic assessment of mitral regurgitation: A new tool to assess severity?

Mitral regurgitation is frequently classified as mild, moderate or severe based on echocardiography. Patients with mild mitral regurgitation are usually managed medically. We hypothesise that mild mitral regurgitation as assessed volumetrically can in fact be severe when analysed from a bioenergetics point of view. The conservation of energy predicts that any regurgitant volume will require the heart to provide more work energy to support the circulation. Mitral regurgitation involves the left ventricle imparting potential energy, via blood pressure, and kinetic energy, via regurgitant velocity, to the regurgitant blood volume. This implies that regurgitant volume, regurgitant velocity, systolic blood pressure, heart rate, regurgitant orifice area and cardiac output are all important factors. We present limited data to demonstrate our hypothesis. A bioenergetic analysis of mitral regurgitation, may identify patients whose mitral regurgitation, assessed via echocardiography as mild, is actually clinically significant. In addition we identify the importance of blood pressure and heart rate control in patients with mitral regurgitation. The concept that a bit of mitral regurgitation in patients with poor left ventricles is a good thing, as it helps offload the left ventricle is from an engineering point fundamentally flawed.     

Quantification of mitral regurgitation using Doppler echocardiography

Examining 18 patients without regurgitation (control group) and 20 patients with mitral regurgitation the method of Doppler echokardiography, the pulsating and continual wave, was applied. Both groups consisted of patients with heart diseases in whom a heart catheterization was indicated for the evaluation of the actual state. Thus, the competence of the mitral orifice was also evaluated. The aim of the investigation was to quantify or more accurately estimate the degree of mitral regurgitation. The accuracy of the Doppler method was tested by means of the measured cardiac stroke volumes of the right heart side in both groups with the probability higher than 80% but lower than 90% (0.80 less than p 0.23 less than 0.90), and by testing the cardiac stroke volumes of the right heart and the diastolic volumes of the left heart (control group: mitral and pulmonal orifice) with the probability higher than 70% and lower than 80% with the error of 6% of the measured volume. The regurgitation mitral fraction (RF) was presented as the difference between the total forwards volume (TFV) in the mitral orifice and the net forwards volume (NFV) in the pulmonal orifice and calculated in cm3, and as the regurgitation fraction index (RFI) in percentages (RFI = 1--NFV/TFV). It was also expressed as the regurgitation volume index (RVI) whose values were divided into degrees, according to the literature data. Numerical values of the regurgitation fraction and the regurgitation fraction index were classified in the mitral insufficiency degrees from 1 to 4. A fast regurgitation screening was possible due to the regurgitation fraction index, which is lower than the 45% of the diastolic volume in the cases of mild mitral insufficiency, while the values over 45% denote severe mitral insufficiency. The obtained values of the regurgitation fraction and index divided into degrees showed a close correlation with the angioventriculographic degrees obtained by heart catheterization. Cardiac output measured by the Doppler and Fick methods in the group with regurgitation showed a high correlation coefficient (r = 0.85) (0.60 less than p 0.47 less than 0.70).     

Gepulste Doppler-Echokardiographie bei Aortenvitien

Summary The diagnostic value of pulsed Doppler echocardiography (PDE) had not been sufficiently assessed up until now. Invasive catheter velocitometric measurements in the central vessels give quantitative information on the blood movement across the aortic and pulmonary valves. It is particularly useful in the quantification of aortic regurgitation. We successfully investigated 52 patients by means of PDE (ATL 500 A); 20 were suffering pure aortic incompetence, 11 pure stenosis and 21 had combined stenosis and regurgitation. Fifteen patients without aortic valvular disease served as controls. Our findings were compared with the results of cardiac catheterization and angiography in each case. In addition, 14 patients with aortic regurgitation were studied invasively by catheter velocitometry. The obtained regurgitation values were compared to the PDE method. In the PDE the underlying criteria for the assessment of the recordings were as follows: formal analysis of the analog signal and of the turbulence content during systole and diastole; in the flow velocity tracings aortic incompetence showed a steep increase with high peak to peak aortic velocities and scant turbulence formation; the reverse flow during regurgitation was accompanied by a high grade turbulent velocity pattern. The area under the diastolic (regurgitant) flow velocity curve (the time-amplitude integral) corresponded significantly with the angiographic severity of aortic insufficiency (r=0.87). In aortic stenosis, turbulence formation leads to an approximately flat velocity profile across the ascending aorta, if the region in the vicinity of the valve is omitted. The flow velocity analog signals are considerably disturbed. However, the turbulence content which can be qualitatively estimated from the recordings, correlates well with the calculated valve area. In combined aortic valve stenosis and incompetence, the prevailing turbulent pattern does not always permit one to assess sufficiently the severity of the stenotic component, whereas the grade of incompetence can be, in general, evaluated. PDE complements the existing non-invasive techniques and probably essentially enriches non-invasive diagnostics.

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Abkürzungsverzeichnis A Vorwärtsfluß - AI Aorteninsuffizienz - Ao Aorta ascendens - AS Aortenstenose - B Rückwärtsfluß - CTV Katheter-Tip-Velocitometrie - Flow Flußgeschwindigkeit - H positive Amplitude der Strömungskurve - LA linker Vorhof - LV linker Ventrikel - MAT Maximale Amplitude der Turbulenz - O Strömungsnull - PDE Gepulste Doppler-Echokardiographie - RPA Rechte Pulmonalarterie - RV Rechter Ventrikel - SV sample volume - T _syst systolisches Zeitintervall - U _max Strömungsgeschwindigkeit - _max Blutbeschleunigung     

Perkutane transfemorale Valvuloplastie bei Patienten mit kalzifizierter Aortenstenose und deutlich erhöhtem Operationsrisiko: Klinischer Verlauf und Wertigkeit der Dopplersonographie zur Beurteilung des Therapieerfolges

Summary Percutaneous transluminal valvuloplasty (PTV) was performed in 24 patients (aged 67–86 years, mean: 76±5.7 years) with calcific aortic stenosis and high operative risk. The gradient between maximal left ventricular and aortic pressures (peak-to-peak gradient, PPPG) could be reduced by 52% from 73±21 to 34±12 mmHg (p<0.001). Peak pressure gradient (PPG), as assessed by continuous wave Doppler, could be reduced from 80±28 to 58±21 mmHg (p<0.001). Aortic valve area (AVA) as determined by Doppler and two dimensional echocardiography increased significantly from 0.39±0.14 to 0.61±0.3 cm² (p<0.05). Clinical symptoms were found to be improved in 5 of 8 patients with impaired ejection fraction and in 11 of 16 patients with normal ejection fraction during the first week after PTV. Complications due to the procedure were surgical revision of femoral artery puncture site in one patient and hemodynamic relevant pericardial effusion in another patient. Transmitral early (E) and late (L) diastolic filling integrals were measured by pulsed Doppler: the ratio E/L decreased significantly after PTV from 0.9±0.5 to 0.63±0.31 (p<0.03) indicating further reduction of left ventricular early diastolic filling. Ejection fraction, stroke volume and cardiac output did not significantly change immediately after PTV.The results indicate, that PTV can successfully reduce aortic pressure gradients and improve symptoms in patients with calcific aortic stenosis and high operative risk. Doppler echocardiography provides an adequate method to noninvasively evaluate the initial outcome of PTV and seems valuable for the assessment of long term results.

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Abkürzungsverzeichnis AKE prothetischer Aortenklappenersatz - AoP maximaler systolischer Aortendruck - AVA Aortenklappenöffnungsfläche - E Integral frühdiastolischer Füllungsgeschwindigkeiten - EF Ejektionsfraktion - HR Herzfrequenz - HZV Herzzeitvolumen - L Integral spätdiastolischer Füllungsgeschwindigkeiten - LVP maximaler systolischer linksventrikulärer Druck - NYHA New York Heart Association - PPG peak pressure gradient - PPPG peak-to-peak pressure gradient - PTV Perkutane transmfemorale Valvuloplastie - SEP Systolische Ejektionsperiode - SV Schlagvolumen     

Gepulste Doppler-Echokardiographie bei prothetischem Aorten- und Mitralklappenersatz

Summary In 94 subjects with normally functioning heart valve prostheses (51 aortic and 43 mitral valve prostheses) and in 35 patients with intact aortic and mitral valves, blood flow velocity within the heart and the aortic root have been recorded using pulsed Doppler velocity studies in patients with diseased valves of the left heart. In addition, a further 7 patients were investigated using invasive catheter tip velocitometry, pre- and postoperatively. The preversus postoperative changes of maximum velocity and acceleration is characterized as follows: postoperative flow velocity tracings show approximately normal profiles comparable to normal valve function. Turbulence formation is diminished and the steep uptroke of the normal flow pattern is restituted. Differencies in transprosthetic blood flow patterns dependent on the implanted prosthesis model can be defined. Bioprostheses, in particular the Carpentier-Edwards device, reliably approximate normal amplitude-time characteristics. This is also true for the St. Jude Medical prosthesis with central flow properties. Velocitometric signs of valve dysfunction were detected in 9 patients: sensitivity was 100%; specificity ranged from 76% in aortic to 96% in mitral prostheses. Pulsed Doppler echocardiography therefore is a useful complement in the non-invasive haemodynamic tools and can be repeatedly applied to a patient with prosthetic cardiac valve replacement.

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Abkürzungsverzeichnis A Vorwärtsfluß - AI Aorteninsuffizienz - AS Aortenstenose - AV kombiniertes Aortenvitium - B Rückfluß - BS Björk-Shiley-Ventil - CE Carpentier-Edwards-Bioprothese - CTV Katheter-Tip-Velocitometrie - H Strömungsamplitude (mm) - H1/T1 Strömungssteilanstieg (cm/s) - HK Hall-Kaster-Ventil - HPX Hancock-Bioprothese - LE Lillehei-Kaster-Ventil - MAT Maximale Strömungsturbulenz (%) - MI Mitralinsuffizienz - MS Mitralstenose - MV kombiniertes Mitralvitium - O Strömungsnull - PDE gepulste Doppler-Echokardiographie - RF Regurgitationsfraktion (%) - SE Starr-Edwards-Ventil - SJM St. Jude Medical-Prothese - T Zeitabschnitt in der Strömungskurve (s) - U _max maximale Blutströmungsgeschwindigkeit (cm/s) - {ie76-1}_max maximale Strömungsbeschleunigung (g) In memoriam Prof. Dr. A. Vöge     

A Novel Coaptation Plate Device for Functional Mitral Regurgitation: An In Vitro Study

A novel mitral valve repair device, coaptation plate (CP), was proposed to treat functional mitral regurgitation. The objective of this study was to test efficacy of the CP in an in vitro model of functional mitral regurgitation. Ten fresh porcine mitral valves were mounted in a left heart simulator, Mitral regurgitation was emulated by means of annular dilatation, and the asymmetrical or symmetrical papillary muscles (PM) displacement. A rigid and an elastic CPs were fabricated and mounted in the orifice of regurgitant mitral valves. Steady flow leakage in a hydrostatic condition and regurgitant volume in a pulsatile flow were measured before and after implantation of the CPs. The rigid and elastic CPs reduced mitral valve regurgitant volume fraction from 60.5 ± 11.4 to 35 ± 11.6 and 36.5 ± 9.9%, respectively, in the asymmetric PM displacement. Mitral regurgitation was much lower in the symmetric PM displacement than in the asymmetric PM displacement, and was not significantly reduced after implantation of either CP. In conclusion, both the rigid and elastic CPs are effective and have no difference in reduction of functional mitral regurgitation. The CP does not aggravate mitral valve coaptation and may be used as a preventive way.     

Value of a modified continuity equation method to quantify mitral valve area in patients with mitral stenosis and sinus rhythm

Summary To quantify valve area in mitral stenosis, a modified continuity equation method using continuous wave Doppler and thermodilution measurements was applied. In 14 patients with mitral stenosis and sinus rhythm (age: 49±11 years), transmitral flow velocity was recorded by continuous wave Doppler during right and left heart catheterization. Mitral valve area was calculated by three different methods: 1. According to the continuity equation, stroke volume (thermodilution technique) was divided by the registered time velocity integral of the mitral stenotic jet (continuous wave Doppler). 2. Mitral valve area was calculated by the pressure half-time method. 3. Simultaneous pulmonary capillary wedge and left ventricular pressure measurements were used for determination of mitral valve area according to the Gorlin formula. The mitral valve area determined by application of the continuity equation (y) showed a close correlation to the valve area calculated by the Gorlin equation (x):y=0.73x+0.12, SEE=0.11 cm²,r=0.88,P<0.001. In contrast, the correlation between mitral valve area determined by pressure half-time (y) and the Gorlin formula (x) was not as good:y=0.77x+0.11, SEE=0.26 cm²,r=0.65,P<0.05. Thus, the continuity equation method using combined continuous wave Doppler and thermodilution technique allows a valid determination of mitral valve area. In patients with mitral stenosis and sinus rhythm, this technique is superior to the noninvasive determination of mitral valve area by the conventional pressure half-time method.Abbreviations bpm beats per minute - CO cardiac output - DFT diastolic filling time - HR heart rate - LV left ventricular - MMVG mean mitral valve gradient - MVA_CE mitral valve area determined according to the continuity equation method - MVA_G mitral valve area calculated according to the Gorlin formula - MVA_T1/2 mitral valve area determined according to the pressure half-time method - PCW pulmonary capillary wedge - SV stroke volume     

The pathogenesis of acute pulmonary edema associated with hypertension

BACKGROUND: Patients with acute pulmonary edema often have marked hypertension but, after reduction of the blood pressure, have a normal left ventricular ejection fraction (> or =0.50). However, the pulmonary edema may not have resulted from isolated diastolic dysfunction but, instead, may be due to transient systolic dysfunction, acute mitral regurgitation, or both. METHODS: We studied 38 patients (14 men and 24 women; mean [+/-SD] age, 67+/-13 years) with acute pulmonary edema and systolic blood pressure greater than 160 mm Hg. We evaluated the ejection fraction and regional function by two-dimensional Doppler echocardiography, both during the acute episode and one to three days after treatment. RESULTS: The mean systolic blood pressure was 200+/-26 mm Hg during the initial echocardiographic examination and was reduced to 139+/-17 mm Hg (P< 0.01) at the time of the follow-up examination. Despite the marked difference in blood pressure, the ejection fraction was similar during the acute episode (0.50+/-0.15) and after treatment (0.50+/-0.13). The left ventricular regional wall-motion index (the mean value for 16 segments) was also the same during the acute episode (1.6+/-0.6) and after treatment (1.6+/-0.6). No patient had severe mitral regurgitation during the acute episode. Eighteen patients had a normal ejection fraction (at least 0.50) after treatment. In 16 of these 18 patients, the ejection fraction was at least 0.50 during the acute episode. CONCLUSIONS: In patients with hypertensive pulmonary edema, a normal ejection fraction after treatment suggests that the edema was due to the exacerbation of diastolic dysfunction by hypertension--not to transient systolic dysfunction or mitral regurgitation.     

Transapical Coaptation Plate for Functional Mitral Regurgitation: An<Emphasis Type="Italic"> In Vitro</Emphasis> Study

A novel transapical coaptation plate (TCP) device was developed and anchored by sutures in the mitral valve to treat functional mitral regurgitation. The objective of this study was to test efficacy of the TCP in an in vitro model. Eight fresh porcine mitral valves were mounted in a left heart simulator to simulate functional mitral regurgitation by means of annular dilatation and asymmetrical or symmetrical papillary muscle (PM) displacement. Six polyurethane TCPs in thickness of 6.4(#1), 4.8(#2), 3.2(#3) mm and hardness of durometer 30 A (H) and 30 OO(S),were fabricated and labeled as H1, H2, H3 and S1, S2, S3, respectively. These TCPs were anchored by the sutures in the mitral annulus and left ventricle apex, and tested. Steady backward flow leakage in a hydrostatic condition and regurgitant volume in a pulsatile flow were measured before and after implantation of the TCPs. Mean regurgitant volume fractions in the asymmetric PM displacement were reduced significantly from 59.1 to 37.2% for H1, 43.2% for H2, 35.9% for S1 and 34.2% for S2 (p < 0.021), after implantation of the TCPs. No significant reduction in mitral regurgitation was seen for H3 and S3 (p > 0.067). Mitral regurgitation was mild in the symmetric PM displacement, and was not significantly reduced after implantation of the TCPs. In conclusion, the TCP anchored by the sutures in the mitral annulus and left ventricle apex functions successfully as a plug in the mitral valve leaflet gap. The TCP with thickness equal to or greater than 4.8 mm is effective to reduce functional mitral regurgitation. The TCP hardness has no effect on difference in reduction of functional mitral regurgitation.     

Beat-to-beat noninvasive stroke volume from arterial pressure and Doppler ultrasound

The proper understanding of the cardiovascular mechanisms involved in complaints of short-lasting dizziness and the evaluation of unexplained recurrent syncope requires continuous monitoring of cardiac stroke volume (SV) in addition to blood pressure and heart rate. The primary aim of the present study was to evaluate a pulse wave analysis method that calculates beat-to-beat flow from non-invasive arterial pressure by simulating a non-linear, time-varying model of human aortic input impedance (Modelflow; MF), by comparing MF stroke volume (SV_MF) to Doppler ultrasound (US) flow velocity SV (SV_US). A second purpose was to compare the two methods under two different conditions: the supine and head-up tilt (30°) position. SV_US and SV_MF with non-invasive arterial pressure (Finapres) as input to the aortic model were measured beat-to-beat during spontaneous supine breathing and in the passive 30° head-up tilt (HUT30) position in six normotensive healthy humans [three females, mean age 24 (21–26) years]. There were variations in supine SV track between the two methods with zero difference and a SD of the beat-to-beat difference (MF–US) of 4.2%. HUT30 induced a systematic difference of 10.5% and an increase in SD to 6.9%, which was reproducible. Beat-to-beat changes in SV in the supine resting condition were equally well assessed by both methods. Systematic differences appear during HUT30 and show opposite signs. The difference between the two methods upon a change in body position may be attributed to limitations in each method.     

A Dynamic Heart System to Facilitate the Development of Mitral Valve Repair Techniques

Objective: The development of a novel surgical tool or technique for mitral valve repair can be hampered by cost, complexity, and time associated with performing animal trials. A dynamically pressurized model was developed to control pressure and flowrate profiles in intact porcine hearts in order to quantify mitral regurgitation and evaluate the quality of mitral valve repair. Methods: A pulse duplication system was designed to replicate physiological conditions in explanted hearts. To test the capabilities of this system in measuring varying degrees of mitral regurgitation, the output of eight porcine hearts was measured for two different pressure waveforms before and after induced mitral valve failure. Four hearts were further repaired and tested. Measurements were compared with echocardiographic images. Results: For all trials, cardiac output decreased as left ventricular pressure was increased. After induction of mitral valve insufficiencies, cardiac output decreased, with a peak regurgitant fraction of 71.8%. Echocardiography clearly showed increases in regurgitant severity from post-valve failure and with increased pressure. Conclusions: The dynamic heart model consistently and reliably quantifies mitral regurgitation across a range of severities. Advantages include low experimental cost and time associated with each trial, while still allowing for surgical evaluations in an intact heart.     

高血压合并阵发性房颤患者心脏超声临床特点

目的:观察分析高血压合并阵发性房颤患者的心脏超声特点,为临床准确诊断提供依据。方法:选取2019年08月至2020年08月我院收治的51例高血压合并阵发性房颤患者作为研究组,同时选取51例单纯高血压患者作为常规组,所有患者均接受心脏超声诊断确定有无二尖瓣返流;同时观察心脏收缩期右房上下径、左房前后径、室间隔厚度、舒张期左心室末期内径、左室射血分数、早期二尖瓣血流速度/心房收缩时二尖瓣充盈峰速(Early mitral valve velocity/Mitral valve filling peak velocity during atrial contraction,E/A)。结果:研究组与常规组血压、腰围、BMI指数、血脂、血糖以及血尿素氮无差异(p>0.05);研究组二尖瓣返流病例数多于常规组(P<0.05);研究组E/A、室间隔厚度、收缩期左房前后径均高于常规组(P<0.05),而收缩期右房上下径、舒张期左心室末期内径、左室射血分数无差异(P>0.05)。通过Logistic分析发现,二尖瓣反流、室间隔厚度、收缩期左房前后径与阵发性房颤相关(P<0.05)。结论:高血压合并阵发性房颤的心脏超声特点包括:室间隔厚度增加、左心房扩大、二尖瓣返流等,与单纯高血压差异显著。     

Hämodynamik,Volumina und Dehnbarkeit des linken Ventrikels bei 167 Patienten mit angeborenen und erworbenen Herzfehlern

Zusammenfassung An 167 Patienten mit angeborenen und erworbenen Herzfehlern (Ventrikelseptumdefekt (VSD), Vorhofseptumdefekt (ASD), hypertrophische obstruktive Kardiomyopathie (HOK), Mitralstenose (MS), Mitralinsuffizienz (MI), kombinierte Mitralvitien (MV), Aortenstenose (AS), Aorteninsuffizienz (AI), kombinierte Aortenvitien (AV)) wurden hämodynamische Größen (Drucke im rechten und linken Herzen, Herzminutenvolumen, Herzindex, Schlagvolumen, Herzarbeit u.a.), linksventrikuläre Volumina (enddiastolisches Volumen, endsystolisches Volumen, Auswurffraktion, Regurgitationsvolumen) sowie diastolische Druck-Volumen-Beziehungen auf der Basis diastolischer Druckänderungen und ventriculographisch gemessener diastolischer Volumenänderungen ermittelt.1. Das enddiastolische Volumen im linken Ventrikel (HOKHOK>ASD>AV>MI>AI>MV>AS>VSD>MS) was 72 per cent (normal) and was lowest in MS (52 per cent). Regurgitant flow of the aortic and mitral valves varied between 38–62 per cent of total stroke volume (AI, MI, MV, AV). There existed a good correlation between ejection fraction and isovolumic indices of myocardial contractility.2. Left ventricular enddiastolic pressure as well as diastolic pressure difference (NdP/dV) (AIdP/dV, that is the greatest ventricular wall stiffness, was found for AS and HOK with increases by 160 per cent and 245 per cent respectively. Diastolic pressure volume relationship exhibited differences in steepness in accord with changes in diastolic compliance.The results demonstrate changes in left ventricular compliance determined on the basis of directly measured left ventricular diastolic pressure and volume changes in congenital and acquired heart disease associated with pressure and/or volume overload. The possibilities and limitations of calculating left ventricular compliance from diastolic pressure volume relationships, the underlying mechanisms and the hemodynamic consequences are discussed.

     

Netto-Effekte von Atembewegungen auf den Kreislauf am narkotisierten Hund

Zusammenfassung Um den mechanischen Nettoeffekt der Atembewegungen auf den Kreislauf zu bestimmen, wurden an narkotisierten Hunden die wichtigsten Kreislaufgrößen (Herzzeitvolumen, Herzfrequenz, Schlagvolumen, arterieller Blutdruck, peripherer Widerstand) vergleichend bei Atemstillstand und bei Spontanatmung oder bei künstlicher Beatmung gemessen, wobei Veränderungen der Blutgase vermieden oder ihre Effekte berücksichtigt wurden.Es wurden die folgenden wichtigsten Befunde erhoben: 1. Sowohl bei Spontanatmung als auch bei künstlicher Beatmung war die Herzfrequenz im Vergleich zum Atemstillstand erhöht (bis um 30%). 2. Bei Spontanatmung wurde diese Zunahme der Herzfrequenz von einer gleich großen Zunahme des Herzzeitvolumens begleitet. Bei künstlicher Beatmung dagegen nahm dabei das Schlagvolumen so ab, daß das Herzzeitvolumen etwa konstant blieb. 3. An vagotomierten Tieren, bei denen keine Herzfrequenzveränderungen auftraten, hatte Spontanatmung keinen Effekt auf den Kreislauf, während bei künstlicher Beatmung das Herzzeitvolumen und das Schlagvolumen im Vergleich zum Atemstillstand etwas erniedrigt waren.Aus den Befunden wurde gefolgert: 1. Künstliche und spontane Atembewegungen steigerten reflektorisch die Herzfrequenz. 2. Die künstlichen Atembewegungen an sich bedingten eine Abnahme des Schlagvolumens und des Herzzeitvolumens. 3. Die spontanen Atembewegungen an sich schienen keinen mechanischen Nettoeffekt auf den Kreislauf zu haben.

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Summary In order to determine the mechanical net effect of respiratory movements on the circulation, the principal circulatory parameters (cardiac output, cardiac frequency, stroke volume, arterial blood pressure, peripheral resistance) were measured in anesthetized dogs comparatively during apnea and during spontaneous breathing or during artificial ventilation. Changes in blood gases were avoided or their effects were taken into account.The following results were obtained: 1. During spontaneous breathing as well as during artificial ventilation the cardiac frequency was increased as compared to apnea (up to 30%). 2. During spontaneous breathing this increase in the cardiac frequency was accompanied by a corresponding increase in the cardiac output. During artificial ventilation the stroke volume decreased simultaneously in such a manner that the cardiac output remained unchanged. 3. In vagotomized animals, in which no changes of the cardiac frequency occurred, spontaneous respiration had no influence on the circulation, whereas with artificial ventilation the cardiac output and the stroke volume were decreased as compared to apnea.It was concluded from the results: 1. Artificial and spontaneous respiratory movements increased the cardiac frequency reflexly. 2. The artificial respiratory movements per se reduced the stroke volume and the cardiac output. 3. The spontaneous respiratory movements appeared to have no direct mechanical net effect on the overall circulation.

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Mit 3 Textabbildungen

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Für finanzielle Unterstützung danken wir der Bergbau-Berufsgenossenschaft, Bochum.     

Analog simulation of aortic and of mitral regurgitation

By using an equivalent electronic circuit either mitral or aortic regurgitation was simulated. Simulation allowed not only a measurement of various pressures within the cardiovascular system and cardiac output, but also mitral and aortic flow.In normal conditions mitral and aortic flows were monophasic, anterograde. In valve regurgitation mitral and aortic flows were, as expected, biphasic.In mitral regurgitation, during systole and diastole the valve flow was retrograde and anterograde, respectively.In aortic regurgitation, during systole and diastole the valve flow was anterograde and retrograde, respectively.The magnitude of the regurgitant valve flow was measured by time-integration and compared to the net flow, i.e. cardiac output. Valve flow was determined not only by the magnitude of valve dysfunction, but also by the resistive/capacitive characteristics of the “falsely” attached regurgitant circuit. If the regurgitant valve flow was large enough, it in turn affected the function of the left ventricle.The present investigation suggests that many features observed in patients with mitral or aortic regurgitation can be qualitatively satisfactorily simulated. In some respects even quantitative simulation is possible. However, for simulation of chronic mitral or aortic regurgitation, in the analog electronic circuit additional adjustments—in capacitance of the left ventricle and pulmonary system—would be required.     

两种人工瓣环置入修复单纯二尖瓣环扩张引起的二尖瓣关闭不全的比较

背景：退行性二尖瓣关闭不全的病例有逐渐增加的趋势,而单纯二尖瓣环扩张引起的二尖瓣关闭不全是退行性二尖瓣关闭不全的一种类型,国内尚无关于此类二尖瓣关闭不全的外科治疗的临床研究报告。 目的：观察单纯瓣环置入修复单纯二尖瓣环扩张引起的二尖瓣关闭不全早中期生物相容性的反应。 方法：单纯二尖瓣瓣环扩张致二尖瓣关闭不全患者48例,均行二尖瓣人工瓣环置入修复,其中使用Carpentier-Edwards生理环23例、SJMTM刚性鞍形成形环25例。出院后随访,采用超声心动图观察心功能和二尖瓣反流程度等变化,并比较两种瓣环与宿主生物相容性有无差别。 结果与结论：围术期无死亡,均治愈出院。48例均获随访,随访率100%,随访时间3个月至4年,无死亡病例。NYHA心功能分级Ⅰ级32例,Ⅱ级16例。与术前比较,随访期超声心动图显示左心房内径、左心室舒张末期内径、左心室收缩末期内径、肺动脉收缩压和反流速面积/左房面积均明显减少(P < 0.01),左室射血分数明显增加(P < 0.01)。跨瓣压差均< 3 mm Hg。二尖瓣无明显返流36例,微量返流10例,轻度反流2例。未出现成形环断裂、成形环撕脱及溶血现象。Carpentier-Edwards生理环组和SJMTM刚性鞍形成形环组比较,上述各指标差异无显著性意义(P > 0.05)。结果提示对于因单纯二尖瓣环扩张引起的退行性二尖瓣关闭不全,通过正确的置入技巧、选择合适的人工瓣环,应用人工瓣环置入有与宿主生物较好的生物相容性反应,置入后的瓣膜替代功能良好。中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程全文链接：     

Evaluation of the theory of cardiac-output computation from transthoracic impedance plethysmogram

To analyse the limit of the stimation of stroke volume by thoracic impedance plethysmography (SV_z), we considered an elastic tube forced with a trapezoidal flow input as a model of the aorta, and, based on Kubicek's equation, the volume input (SV_a) was related to its impedance change via the model system parameters such as elasticity, fiuid inertia, peripheral resistance, total impedance across the tube and the rise and fall time of the input. SV_z is equal to SV_a only when the inflow is a square wave. The ratio SV_z/SV_a decreases with increasing input rise time, while it increases with increasing fall time, if the maximum flow rate and ejection time of the inflow are held constant. SV_z hardly changes in association with changes in elasticity, fluid inertia, peripheral resistance or total impedance. A part of the results, the relationship between SV_z, transthoracic total impedance and aortic flow waveform, was also demonstrated in dogs.     

Die Druckbelastung bei diastolischer Volumkonstanz beim isolierten Froschherzen

Zusammenfassung Die Druckbelastung bei diastolischer Volumkonstanz als neuer methodischer Begriff der Herzmechanik (bzw. der Mechanik eines Hohlmuskels überhaupt) wird eingeführt und erklärt. Grundsätzliche methodische Möglichkeiten zur Durchführung einer volumkonstanten Drucksteigerung des Herzens werden angegeben. Eine eigene mechanisch funktionierende Apparatur zur Volumenarretierung des isolierten Froschherzens bei auxotonischer Tätigkeit wird beschrieben. Vorläufiges Ergebnis von (14) mit dieser Methodik durchgeführten Versuchen: Das Schlagvolumen des auxotonisch tätigen Herzens bleibt bei Drucksteigerungen bis zu 10 cm H₂O in ungefähr vier Fünftel der Fälle unverändert; das Bestehen eines in den restlichen Fällen beobachteten geringen inotropen Effektes ist wahrscheinlich methodisch bedingt.

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Summary Heart action was studied in an isolated frog heart preparation under conditions of pressure increments at constant diastolic volume. The basic methodical possibilities to increase pressure at a constant diastolic volume of the heart ventricle are described and the mechanically functioning apparatus used in our experiments is explained. Preliminary results indicate, that there is mostly no change in stroke volume at auxotonic work up to filling pressures of 10 cm H₂O (80% of the cases). A slight inotropic effect seen in the remaining cases may have methodical reasons.

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