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PubMed1990

Differential enhancement of postischemic segmental systolic thickening by diltiazem.

Prolonged depression of segmental systolic thickening after brief coronary artery occlusion may result principally from events during reperfusion rather than during the ischemic interval. Thus, cellular calcium overload at reperfusion may be a mediator of contractile dysfunction after brief ischemia, and reduction of calcium entry by diltiazem, a calcium channel antagonist, may enhance recovery of systolic thickening after brief periods of ischemia. Thirteen awake unsedated dogs instrumented with hemodynamic catheters, left anterior descending coronary artery occluders and five to six pairs of intramyocardial sonomicrometers underwent two 15 min coronary artery occlusions with 24 h reperfusion. The order of infusion of diltiazem (15 micrograms/kg per min) or saline solution was alternated. Systolic thickening, hemodynamic variables and regional myocardial blood flow were measured serially over 24 h. Despite equally severe ischemic dysfunction during coronary occlusion, diltiazem-treated segments with systolic thinning during ischemia recovered control segmental thickening significantly earlier than saline solution-treated segments (at 30 versus 180 min of reperfusion). Blood pressure was mildly decreased during diltiazem treatment; therefore, a second group of 10 dogs underwent a similar occlusion and reflow period during infusion of nitroprusside to lower mean arterial pressure equivalently. Decreases in blood pressure in this group resulted in some improvement in segmental systolic function; however, this did not reach statistical significance at any time. Regional myocardial blood flows were similar in the saline solution- and diltiazem-treated groups during ischemia and reflow. Thus, it is concluded that 1) diltiazem infusion significantly enhanced recovery of segmental systolic thickening after 15 min of ischemia and 24 h of reperfusion; 2) the enhancement in segmental systolic function could not entirely be attributed to decreased mean arterial pressure; 3) improvement in postischemic segmental ventricular function was seen only in those segments with systolic thinning during ischemia; thus, segments with the most severe ischemic dysfunction benefited most; and 4) there were no important differences in regional myocardial blood flow during ischemia and reperfusion between saline- and diltiazem-treated animals.

Animals↗
PubMed1994

Regional nonischemic performance as assessed by end-systolic measures of shortening and thickening.

OBJECTIVES: Nonischemic contractile segmental performance was characterized by the end-systolic pressure-length and pressure-thickness relations during regional ischemia induced by proximal left anterior descending and left circumflex coronary artery occlusions. BACKGROUND: The increases in shortening and thickening of the nonischemic myocardium during acute ischemia have been attributed to alterations in the regional loading conditions. However, it is uncertain to what extent ischemia affects the contractile performance of the nonischemic zone. METHODS: Twenty-seven beagle dogs were instrumented with sonomicrometers and micromanometer pressure gauges. End-systolic pressure-length and pressure-thickness relation data were obtained during vena cava balloon inflation. Control data were obtained in both left anterior descending and left circumflex regions. Then, in random order, either the left anterior descending or left circumflex coronary artery was occluded for 90 s, and hemodynamic and nonischemic end-systolic pressure-length and pressure-thickness data were obtained. After a 45-min recovery period, the other artery was occluded, and the same recordings were obtained. RESULTS: The end-systolic pressure-length relation exhibited variable degrees of rightward and downward shifts and the end-systolic pressure-thickness relation variable degrees of leftward and downward shifts. Left circumflex coronary artery occlusion was associated with a greater downward displacement (decreased slope) of the nonischemic end-systolic pressure-length relation than left anterior descending coronary artery occlusion. The baseline slope was the best predictor of the change in slope of the end-systolic pressure-length and pressure-thickness relations. The left circumflex coronary artery supplied a larger proportion of left ventricular myocardial mass than the left anterior descending coronary artery. CONCLUSION: Acute ischemia profoundly affects the end-systolic performance of the nonischemic segment. Furthermore, the site, and probably size, of the ischemic zone may be important determinants of nonischemic contractile performance.

Animals↗
PubMed1997

Transesophageal Doppler echocardiographic assessment of systolic and diastolic coronary blood flow velocities at baseline and during adenosine triphosphate-induced coronary vasodilation in chronic aortic regurgitation.

Few reports exist on the changes in systolic and diastolic coronary flow velocities (CFVs) at baseline and during coronary vasodilation in patients with chronic aortic regurgitation (AR). We examined the left anterior descending CFVs in 21 patients with AR (11 patients with mild AR and 10 patients with moderate to severe AR), 9 patients without AR (no AR group), and 6 patients who had undergone surgery for moderate to severe AR (postoperation group) with transesophageal Doppler echocardiography. Adenosine triphosphate (ATP) was infused into a peripheral right arm vein at four different doses (35, 70, 100, and 140 micrograms/kg/min). Coronary flow velocity response in systole and diastole was calculated as the ratio of systolic peak and mean and diastolic peak and mean CFVs during maximal ATP infusion to those at baseline. The systolic peak and mean CFVs and the diastolic peak and mean CFVs at baseline were significantly increased in the moderate to severe group compared with those in the other groups (p < 0.05, respectively). Systolic and diastolic CFVs were significantly increased during ATP infusions in the four groups. No significant differences of systolic and diastolic CFVs were observed among the four groups during maximal ATP infusion. The coronary flow velocity response calculated from the peak and mean diastolic CFVs were significantly decreased in the moderate to severe group (1.6 +/- 0.3 and 1.7 +/- 0.4) compared with those in the other three groups (3.6 +/- 0.7 and 3.2 +/- 1.1 in the no AR group, 2.6 +/- 0.6 and 2.5 +/- 0.4 in the mild group, and 2.5 +/- 0.7 and 2.4 +/- 0.6 in the postoperation group) (p < 0.05, respectively). In conclusion, the systolic and diastolic left CFVs at baseline appeared to be significantly increased in patients with moderate to severe chronic AR. However, the velocities during coronary vasodilation by ATP were equal to those in other groups, resulting in a decrease of coronary flow velocity response in systole and diastole.

Adenosine Triphosphate↗
PubMed1983

Aortic valve systolic flutter as a screening test for severe aortic stenosis.

Previous efforts using M-mode echocardiography or 2-dimensional (2-D) echocardiography have not consistently separated patients with and without significant aortic stenosis (AS). We postulated that an aortic valve sufficiently pliant to produce systolic flutter on M-mode echocardiography could exclude significant AS and reviewed the M-mode echocardiograms of 50 consecutive patients (mean age 59 years) catheterized for presumed AS; 2-D echocardiography was also performed in 18 of 50 patients (36%). In 40 of 50 patients (80%) the aortic valve cusps were easily identified on M-mode echocardiography: 19 of 40 (48%) had systolic flutter with a mean aortic valve gradient of 4 +/- 8 mm Hg (mean +/- standard deviation [SD]) and an aortic valve area of 2.8 +/- 0.4 cm2; 21 of 40 (52%) had no systolic flutter with a mean aortic valve gradient of 55 +/- 19 mm Hg and an aortic valve area of 0.7 +/- 0.3 cm2. In the 10 of 50 patients (20%) in whom aortic valve cusps were not clearly identified, the mean aortic valve gradient was 50 +/- 24 mm Hg and the aortic valve area 0.8 +/- 0.4 cm2. Systolic flutter was not seen with an aortic valve gradient greater than 30 mm Hg or an aortic valve area less than 1 cm2. Aortic valve systolic opening by M-mode echocardiography or 2-D echocardiography did not accurately predict the severity of AS. Thus, aortic valve systolic flutter seen on M-mode echocardiography is strong evidence against significant AS, but the absence of systolic flutter does not allow reliable prediction of the severity of AS. The finding of systolic flutter by M-mode echocardiography may be a useful screening test in patients presumed to have AS.

Aortic Valve↗
PubMed2000

Elevated systolic blood pressure as a cardiovascular risk factor.

This paper reviews the evolution of attitudes toward the treatment and diagnosis of hypertension. In particular, there is a growing realization that elevated systolic pressure may be a more valuable measurement in evaluating and controlling hypertension than is generally acknowledged. A large number of epidemiologic studies in a wide variety of populations have revealed that systolic blood pressure exerts a stronger influence than diastolic blood pressure. The largest of these, the Framingham Heart Study, showed that in subjects with systolic hypertension, diastolic blood pressure was only weakly related to the risk of cardiovascular events, but in those with diastolic hypertension, the risk of these events was strongly influenced by the level of systolic pressure. Furthermore, cardiovascular event rates were found to increase steeply with systolic pressure and were higher in cases of isolated systolic hypertension than diastolic hypertension. Clinical trials produced similar results, again suggesting that a greater reliance should be placed on systolic pressure in evaluating the risk of cardiovascular problems. This review concludes that the health community needs to be reeducated to consider the importance of systolic and diastolic blood pressure in assessing appropriate management strategies for hypertensive patients.

Cardiovascular Diseases↗
PubMed2004

Isolated systolic hypertension in a cohort of type 2 diabetic patients.

BACKGROUND AND AIMS: Previous studies of the adverse effects of isolated and borderline isolated systolic hypertension excluded or under-represented type 2 diabetic patients. The aim of this study was to evaluate the prevalence and role of isolated and borderline isolated systolic hypertension in a cohort of 3892 type 2 diabetic patients. METHODS AND RESULTS: The hypertensive patients were classified as treated (n= 1806; 46.4%), untreated diastolic hypertension (n=407; 10.4%), untreated isolated systolic hypertension (n=166; 4.3%) and untreated borderline isolated systolic hypertension (n=625; 16%). A Cox proportional hazard model including several confounders showed that the patients with untreated isolated systolic hypertension were at significantly higher risk of hospital admissions due to cerebrovascular diseases than the normotensive and untreated diastolic hypertensive patients (HR=2.05; 95% CI: 1.2-3.4 and HR=1.97; 95%CI: 1.1-3.5, respectively). In the same model, borderline isolated systolic hypertension significantly correlated with admissions for cerebrovascular diseases in comparison with normotensive patients (HR=1.73; 95% CI: 1.2-2.6). CONCLUSIONS: This is the first report concerning the prevalence of isolated and borderline isolated systolic hypertension in a large cohort of type 2 diabetic patients. The results are in line with population-based estimates. Our data show that isolated systolic hypertension is an independent predictor of hospital admissions due to cerebrovascular diseases.

Age Distribution↗
PubMed2003

Treatment and blood pressure control in isolated systolic hypertension vs diastolic hypertension in primary care.

Cross-sectional surveys on prevalence, treatment and control of hypertension could not satisfactorily distinguish between diastolic hypertension and isolated systolic hypertension because the definition of hypertension included patients under pharmacological treatment. We assessed the situation in the two types of hypertension in general practice in Belgium, based on current blood pressure (BP) measurements and on BP prior to the initiation of drug therapy. Participating physicians enrolled the first 15 at least 55-year-old men visiting the surgery, measured their BP and recorded data on medical history including pretreatment BP, drug utilization, cardiovascular risk factors and target organ damage. Diastolic hypertension was defined as diastolic BP> or =90 mmHg, irrespective of systolic BP, and isolated systolic hypertension as systolic BP > or =140 mmHg and diastolic BP < 90 mmHg. Among 3761 evaluable patients, 74% were hypertensive. Among the 1533 hypertensive patients in whom blood pressure was known prior to treatment (n=965) or who were untreated at the study visit (n=568), 1164 had diastolic hypertension and 369 isolated systolic hypertension. The prevalence of antihypertensive treatment was, respectively, 75 and 25% (P<0.001) in these two types of hypertension. The odds of being treated were independently determined by type of hypertension, severity of hypertension and level of risk (P<0.001). BP was controlled in 25% of all patients with diastolic hypertension and in 13% of all patients with isolated systolic hypertension (P<0.001). About half of the treated patients with systolic hypertension were on a diuretic and/or a calcium-channel blocker. In conclusion, isolated systolic hypertension is less frequently treated than diastolic hypertension, overall BP control is poor and actual drug therapy diverges from recommendations based on placebo-controlled intervention trials.

Aged↗
PubMed1997

A simple versatile method for measuring tail cuff systolic blood pressure in conscious rats.

1. The non-invasive measurement of tail cuff systolic blood pressure in conscious rats is routinely used in long-term cardiovascular studies. There are a number of commercially available tail cuff systems, however, these apparatus are generally expensive and are dedicated for single-task operations. In the present study, a simple method for measuring systolic blood pressure, which requires only minor modifications to the existing hardware found in most cardiovascular laboratories, is described. 2. Systolic blood pressure measurements were made in the conventional manner by determining the systolic blood pressure which coincided with the restoration of the caudal artery pulse. This was achieved by using an inexpensive piezo-electric pulse transducer to detect the pulse, and this was coupled to a standard data-acquisition system (MacLab, ADInstruments) normally set up to record blood pressure. This method was compared with another established tail cuff method, as well as with direct intra-arterial recordings. 3. It was found that the results obtained using both tail cuff systems were in good agreement when systolic blood pressure was measured in Wistar-Kyoto rats and spontaneously hypertensive rats. In addition, systolic blood pressure was measured over 4 weeks in 2K1C rats and sham-operated rats, with both tail cuff methods producing similar results, which were not significantly different from direct intra-arterial recordings in the same animals. 4. Thus, in the present study, with only minor modifications, the same equipment was used for both direct and indirect determinations of systolic blood pressure. This situation differs from other conventional tail cuff systems since these items are designed for a single purpose. Therefore, the current method using piezo-electric sensor/MacLab-technology should be viewed as a relatively simple, flexible and cheap alternative method to measure tail cuff systolic blood pressure in conscious rats.

Animals↗
PubMed2001

Deterioration in peak systolic velocity is closely related to ischaemia during angioplasty: a vectorcardiographic and tissue Doppler imaging study.

We tested the hypothesis that the extent of signs of ischaemia detected by vectorcardiography (VCG) during elective coronary angioplasty (percutaneous transluminal coronary angioplasty; PTCA) is related to systolic and diastolic myocardial velocities, as determined by tissue Doppler echocardiography. A total of 15 patients undergoing PTCA (12 men/three women; age 61+/-9 years), without prior myocardial infarction and with an ejection fraction of >50%, were included. The balloon inflation was repeated three times, with minimum intervals of 2 min between inflations. Tissue Doppler echocardiography was performed, in an apical two- or four-chamber view, before and at the end of each inflation. Peak systolic velocity, time-to-peak systolic velocity (TTP), peak early (E(m)) and late (A(m)) diastolic velocities, the E(m)/A(m) ratio and isovolumic relaxation time were measured in the basal segments of the left ventricle. VCG recordings were carried out during the whole procedure. ST vector magnitude (ST-VM) and ST change vector magnitude (STC-VM) were monitored. The total duration and area of each VCG change during inflation were calculated for each patient. Isovolumic relaxation time, peak E(m) and A(m) values and the E(m)/A(m) ratio did not change significantly during inflation. Peak systolic velocity decreased (6.7+/-2.0 to 5.3+/-1.9 cm/s; P<0.001) and TTP increased (157+/-60 to 192+/-60 ms; P<0.01) during inflation. Both STC-VM time (r=-0.68, P<0.01) and STC-VM area (r=-0.68, P<0.01) were related to peak systolic velocity during inflation. STC-VM time was also related (r=0.55, P<0.05) to the difference in peak systolic velocity during compared with before inflation. ST-VM was less closely related to peak systolic velocity. Thus the duration and degree of ischaemia, as measured by VCG, are related to peak systolic velocity in the basal segments of the left ventricle.

Aged↗
PubMed1997

Two-dimensional echocardiographic evaluation of ventricular systolic function in human fetuses with ductal constriction.

Ventricular systolic function was assessed in fetuses, 18 with and 18 without constriction of the ductus arteriosus by serial two-dimensional and Doppler echocardiographic studies. Ductal constriction was defined as maximum systolic velocity of > 140 cm/s and diastolic flow velocity of > 30 cm/s. Ventricular end-diastolic and end-systolic areas were measured from a four-chamber view and area shortening fraction (SF) was calculated: area SF = (area in end-diastole--area in end-systole)/area in end-diastole. In fetuses with ductal constriction, right ventricular end-diastolic and end-systolic areas were significantly increased and right ventricular area SF decreased significantly compared with those values in fetuses without ductal constriction (186 +/- 48 vs. 150 +/- 30 mm2, 112 +/- 34 vs. 81 +/- 19 mm2 and 0.40 +/- 0.05 vs. 0.47 +/- 0.03, respectively, p < 0.01) without any significant changes in left ventricular area SF. Serial studies were available in eight ductal constriction fetuses before and during indomethacin administration, and after withdrawal of the drug for a mean of 24 h. Both systolic and diastolic ductal flow velocities in all fetuses returned to normal range after discontinuation of the drug. During ductal constriction during indomethacin therapy, right ventricular end-diastolic and end-systolic cavity areas were significantly larger and area SF was significantly less than those values before and after the therapy (179 +/- 38 vs. 157 +/- 30 and 154 +/- 27 mm2, 108 +/- 33 vs. 82 +/- 15 and 83 +/- 15 mm2 and 0.40 +/- 0.07 vs. 0.48 +/- 0.03 and 0.46 +/- 0.03, respectively, p < 0.01). This study suggests that ductal constriction influences right ventricular systolic performance.

Blood Flow Velocity↗
PubMed2000

Pulse pressure and isolated systolic hypertension: association with microalbuminuria. The GUBBIO Study Collaborative Research Group.

BACKGROUND: The long-term risk of end-stage renal disease is high in persons with isolated systolic hypertension, that is, those with an elevation of pulse pressure and not of diastolic pressure. Other data suggest that pulse pressure is a predictor of the hypertension-induced organ damage. Microalbuminuria is considered an early sign of glomerular damage caused by hypertension. The study shows the relationship of pulse pressure and isolated systolic hypertension to microalbuminuria in nondiabetic subjects. METHODS: This is a cross sectional analysis for a population sample of 677 men and 890 women, aged 45 to 64 years, who were without diabetes mellitus and macroalbuminuria. Data collection included: overnight urinary albumin and creatinine excretion; fasting plasma glucose, cholesterol, and creatinine; creatinine clearance; and blood pressure, weight, height, medical history, and smoking habit. Pulse pressure was calculated as systolic minus diastolic pressure. Isolated systolic hypertension was defined as systolic pressure > or =140 mm Hg in persons not on antihypertensive drugs and with diastolic pressure <90 mm Hg. Microalbuminuria was defined as urinary albumin excretion > or =20 microg/min. RESULTS: Pulse pressure and isolated systolic hypertension were significantly related to urinary albumin excretion and the prevalence of microalbuminuria in univariate and multivariate analyses. Controlling for gender and other variables, the risk of microalbuminuria was 1.71 with a 15 mm Hg higher pulse pressure (95% CI, 1.31 to 2.22) and 4.95 in the presence of isolated systolic hypertension (95% CI, 3.15 to 7.76). CONCLUSIONS: In nondiabetic, middle-aged adults, pulse pressure and isolated systolic hypertension are directly related to microalbuminuria, independent of diastolic pressure and other correlates.

Age Distribution↗
PubMed2000

Restrictive left ventricular filling pattern after myocardial infarction: significance of concomitant preserved systolic function.

Restrictive left ventricular (LV) filling identifies a high risk subgroup, following myocardial infarction (MI). The extent and significance of systolic dysfunction in this group is not clear. The aim of our study was to determine the incidence and extent of systolic dysfunction in patients with restrictive filling and nonrestrictive filling examining the prognostic implications. Doppler parameters of LV diastolic function were measured in 102 post-MI subjects within 4 days. Restrictive filling was defined as the presence of E:A ratio > 2 or E:A ratio 1-2 with MDT < or = 140 msec. Follow-up was to a median of 11 months. Restrictive filling (group A) was found in 19 (19%) of 102 patients. Patients with this pattern were more likely to have systolic dysfunction than those without (group B); 63% and 35%, respectively, P = 0.024. Eight (42%) of 19 patients in group A had relatively preserved systolic function. At 11 months 14 patients had developed heart failure (HF), 6 in group A (32%) and 8 in group B (10%), P = 0.012. There were two deaths (11%) in group A and 7 (8%) in group B, P = ns. Seven (88%) of 8 patients in group A with relatively preserved systolic function were alive and free of heart failure at follow-up compared to 4 of 11 patients (36%) in group A with systolic dysfunction (P = 0.026). Restrictive filling can be associated with relatively preserved systolic function after MI and these patients have a relatively good outcome. Patients with restrictive filling post-MI are a heterogeneous group emphasizing the evaluation of both systolic and diastolic function.

Aged↗
PubMed2003

The value of middle cerebral artery peak systolic velocity in the diagnosis of fetal anemia after intrauterine death of one monochorionic twin.

OBJECTIVE: The purpose of this study was to assess the value of the fetal middle cerebral artery peak systolic velocity in the prediction of anemia within 24 hours of the death of one monochorionic twin in twin-to-twin-transfusion syndrome and to establish the correlation between middle cerebral artery peak systolic velocity and hemoglobin concentration in fetuses who are at risk for acute anemia. STUDY DESIGN: Doppler examination of the middle cerebral artery peak systolic velocity was performed in 20 monochorionic survivors of pregnancies that were complicated by twin-to-twin-transfusion syndrome that occurred between 20 and 34 weeks of gestation. Doppler examination was performed before cordocentesis and after intrauterine transfusion when appropriate. Both hemoglobin concentration and middle cerebral artery peak systolic velocity were expressed in multiples of the median. Severe anemia was defined as hemoglobin concentration of <0.55 multiples of the median, and we used the cutoff point of 1.50 times the median values at any gestational age to calculate the sensitivity and specificity of middle cerebral artery peak systolic velocity in detecting moderate or severe anemia. RESULTS: Fetal anemia was confirmed in 10 of 20 fetuses. We performed seven intrauterine transfusions. The sensitivity and specificity of middle cerebral artery peak systolic velocity in the prediction of severe fetal anemia were of 90%, with a false-negative rate of 10%. The correlation between peak systolic velocity and hemoglobin concentration both before and after transfusion was evaluated by regression analysis and was strongly significant. CONCLUSION: In fetuses who are at risk of acute anemia, the measurement of middle cerebral artery peak systolic velocity was found to be a reliable noninvasive diagnostic tool and may be helpful in counseling and planning invasive assessment.

Acute Disease↗
PubMed1991

Localization and regulation of c-fos and c-jun protooncogene induction by systolic wall stress in normal and hypertrophied rat hearts.

The effect of changes in left ventricular (LV) systolic force generation on cardiac c-fos and c-jun protooncogene expression was studied by using isolated beating hearts from male Wistar rats. An isovolumic buffer-perfused heart preparation was utilized in which coronary flow and heart rate were held constant and increments in LV balloon volume were used to generate defined levels of LV systolic wall stress. Using Northern and slot-blot analyses, we found that LV tissue from control hearts that generated high levels of LV systolic wall stress expressed 3- to 4.4-fold higher c-fos and c-jun mRNA levels in comparison with tissue from the respective flaccid right ventricles, and in comparison with LV tissue from hearts that generated minimal LV systolic wall stress. To distinguish the role of passive LV diastolic wall stretch from active LV force generation, we found that distension of the LV balloon per se did not have a significant effect on protooncogene induction in hearts perfused with 2,3-butanedione monoxime, which prevents systolic cross-bridge cycling and force generation. In additional hearts studied at a constant LV balloon volume to generate an LV end-diastolic pressure of 10 mm Hg, c-fos mRNA levels were proportional to the magnitude of peak LV systolic wall stress (r = 0.823, P less than 0.05). In these protocols, Fos protein was localized by immunohistochemistry in myocyte nuclei with minimal staining in fibroblasts and vascular smooth muscle. When c-fos and c-jun mRNA expression was compared in hearts with chronic LV hypertrophy due to ascending aortic banding and age-matched control hearts that generated similar incremental levels of LV systolic wall stress, significantly lower levels of c-fos and c-jun mRNA were measured in the hypertrophied hearts. However, there was no difference in protooncogene mRNA expression in response to stimulation by the Ca2+ ionophore A23187. These data suggest that, in this isolated isovolumic beating heart preparation, the active generation of an acute increment in LV systolic force independent of passive diastolic myocardial stretch causes a rapid induction of both c-fos and c-jun, which is down-regulated in the presence of established LV hypertrophy.

Animals↗
PubMed1980

Effects of changes in the aortic input impedance on systolic pressure-ejected volume relationships in the isolated supported canine left ventricle.

We examined the effects of aortic input impedance alteration on left ventricular pressure, aortic flow and ejected volume (integral value of aortic flow), in an isolated blood perfused ejecting canine heart, with special reference to end-systolic values. A hydraulic model which stimulates an aortic input impedance was attached to the aortic root of an excised heart. Left ventricular end-diastolic pressure was kept constant by electrical pacing. Three coronary arteries were perfused with arterial blood from support dogs. When the peripheral resistance in the hydraulic model was changed, there were inverse linear relationships between stroke volume and mean left ventricular systolic pressure and between ejected volume and pressure at end-systole. Time interval from the onset of contraction to end-systole did not change. Thus the relation between stroke volume and mean left ventricular pressure obtained by changes in peripheral resistance is governed by a source resistance, which can be considered as the contractile state of the ventricle. When the capacitance (arterial compliance) was changed, there was no inverse linear relation between stroke volume and mean systolic pressure. In many cases, there was an inverse linear relationship between ejected volume and pressure at end-systole. However, an increase in capacitance prolonged the time interval from the onset of contraction to end-systole. We conclude that the end-systolic pressure-ejected volume relationship in the ejecting heart is governed not only by contractility but also by arterial capacitance.

Animals↗
PubMed1991

Comparative significance in systolic ventricular interaction.

STUDY OBJECTIVE: The aim was to measure the systolic coupling between the ventricles and to determine the relative importance of ventricular interaction in the pressure development of each ventricle. DESIGN: Acute studies were done in dogs to measure the changes in right and left ventricular pressures (dPr, dPl) caused by sudden changes in left ventricular pressure (dPl') with release of an aortic constriction, and sudden changes in right ventricular pressure (dPr') with release of a pulmonary artery constriction, respectively. The instantaneous cross talk gain [dPr/dPl' (Klr) or dPl/dPr' (Krl)] was calculated during the ejection phase. The potential systolic pressure generated by the contralateral ventricle was evaluated as the cross talk gain multiplied by the contralateral systolic developed pressure. EXPERIMENTAL MATERIAL: Studies were done in eight random source dogs (12-18 kg), anaesthetised with sodium pentobarbitone. MEASUREMENTS AND MAIN RESULTS: The maximal Klr was lower than the maximal Krl, at 0.09 (SD 0.05) v 0.25 (0.06), and the mean Klr also was lower than the mean Krl, at 0.04 (0.02) v 0.10 (0.03), p less than 0.05. The potential right ventricular pressures developed by the left ventricle [maximum 10.3(5.6), mean 4.8(2.7) mm Hg] were not significantly different from the potential left ventricular pressures developed by the right ventricle [maximum 8.8(2.7), mean 3.4(0.7) mm Hg]. However, the ratio between the potential transmitted pressure and the measured developed pressure was greater in the right ventricle [maximum 39.0(21.1), mean 17.8(8.9)%] than in the left ventricle [maximum 11.1(7.1)%, p less than 0.05; mean 3.9(1.5)%, p less than 0.01]. This suggests that about 20-40% of the right ventricular systolic pressure may result from the left ventricle and about 4-10% of the left ventricular systolic pressure may result from right ventricle. CONCLUSIONS: Although the pressure coupling was greater in right to left ventricular interaction, right ventricular pressure generation may be more dependent on the left ventricle. Systolic ventricular interaction may be more important for right ventricular systolic function. Further, the parameters of right ventricular systolic function currently used may be considerably affected by the left ventricle.

Animals↗
PubMed2001

Lowering of blood pressure and coronary blood flow in isolated systolic hypertension.

BACKGROUND: In essential hypertension, the lower limit of autoregulation of coronary flow shifts to higher perfusion and the hypertensive ventricle is at a higher than normal risk of ischemia, and less able to tolerate acute reduction of coronary perfusion pressure. Little is known about pattern of coronary flow in isolated systolic hypertension, a pathologic condition in which the elevated systolic blood pressure is associated with a lower than normal vascular compliance and normal or slightly greater than normal mean arterial pressure and vascular resistance. OBJECTIVE: To evaluate the effects of rapid normalization of blood pressure on coronary blood flow in isolated systolic hypertension. METHODS: We subjected 20 patients with isolated systolic hypertension to intraoperative hemodynamic and transesophageal echocardiographic monitoring during peripheral vascular surgery. Coronary flow velocity integrals and diameters in the left anterior descending coronary artery were evaluated under baseline conditions and after normalization of blood pressure, which occurred spontaneously during anesthesia (10 cases; group 1A) or was induced by infusion of nitrate (10 cases, group 1B). RESULTS: After normalization of systolic blood pressure integrals decreased significantly only for patients in group 1A; percentage changes of diameter were significantly greater for patients in group 1B. Therefore, coronary blood flow after normalization of systolic blood pressure increased for patients in group 1B (by 28+/-25%) and decreased for patients in group 1A (by 30+/-21%). Changes in integrals were inversely related to those in diameter (r= -0.72, P < 0.001); for patients in group 1A changes in coronary perfusion pressure and diameter were related to those of integrals (r= 0.94; P < 0.0005). CONCLUSIONS: In isolated systolic hypertension, despite there being similar changes of the systolic blood pressure, administration of nitrates caused a marked increase of coronary flow through direct effects on coronary circulation, whereas spontaneous normotension was associated with a significant reduction of coronary flow.

Aged↗
PubMed2001

Pmax, end systolic elastance, and Starling's law of the heart.

Starling's law is a description relating the energy released by the contracting ventricle to the end diastolic fiber length. The peak systolic pressure during isovolumic contraction is an example of this relationship; Sunagawa and coworkers (12) termed that pressure Pmax. It may also be estimated during ejecting beats. Here we compare the variable Pmax at a given end diastolic volume with that of end systolic elastance as an indicator of ventricular function, changes in either being indicative of changes in the inotropic state of the heart. We specifically investigate 2 points on the end systolic pressure-volume relationship (ESPVR) plot: 1) the Pmax, EDV point, obtained from the concept of the maximum pressure, Pmax, the pressure an isovolumically contracting ventricle would produce at a given end diastolic volume (EDV); and 2) the end systolic pressure, end systolic volume point. Both points would be expected to shift proportionally with changes in the slope of ESPVR. Data were obtained from 2 published reports in humans in the literature and from a group of 5 dogs subjected to a wide range of preloads and afterloads. High correlations (>0.9) were obtained for changes in the slope of ESPVR and the Pmax, EDV points. The latter, a more readily obtainable variable from single ejecting beats, is proposed as a version of Starling's law, the changes in which are directly comparable with the changes in end systolic elastance. The changes in the end systolic pressure, end systolic volume points, were not as reliable (<0.7).

Animals↗