Experimental Studies Comparing Iohexol and 51Cr-Edta for Glomerular Filtration Rate Measurements

The total plasma clearance as well as the renal clearance of iohexol were evaluated for determination of the glomerular filtration rate (GFR) in 16 anesthetized pigs. The iohexol levels in urine and plasma were measured by X-ray fluorescence. The total plasma clearance of 1 and 4 ml/kg b.w. of iohexol 300 mg I/ml was compared to the simultaneously as well as nonsimultaneously calculated total plasma clearance of 51Cr-EDTA. The total plasma clearance of 51Cr-EDTA and of iohexol turned out to be equal and independent of the injected dose of iohexol. The injected dose did not have any effect on the renal clearance of iohexol either. It is concluded that iohexol and 51Cr-EDTA are similar as marker substances for determination of the GFR.

Simultaneous Urography and Determination of Glomerular Filtration Rate

The total plasma clearance of iohexol at urography and 51Cr-EDTA was compared in 31 patients with di- or tetraparesis. A reference 51Cr-EDTA clearance was also performed 24 hours prior to the urography. The GFR was calculated from one, 2 or 4 plasma samples collected 180, 210, 240 and 270 min after the injection. An X-ray fluorescence analyzer was used for the analysis of iohexol in plasma as well as the contrast medium clearance calculations. It was shown that single or multiple sample clearance of iohexol and 51Cr-EDTA were equivalent methods for measurement of the GFR. The GFR was not affected by iohexol in a dose routinely used for urography. It was concluded that the patient comfort is improved if 51Cr-EDTA clearance is replaced by contrast medium clearance in association with urography.

Comparison of stent free cell area and cerebral lesions after unprotected carotid artery stent placement

OBJECTIVE

This study evaluates the correlation between closed, semi-closed and open-cell stent design and the association between stent type and clinical outcome as well as magnetic resonance imaging (MRI) findings.

DESIGN

A total of 194 patients who underwent unprotected carotid artery stenting (CAS) as well as diffusion-weighted magnetic resonance imaging (DW-MRI) before and after intervention were retrospectively reviewed.

MATERIALS AND METHODS

Three stent designs were studied: closed cell, semi-closed cell and open cell. Spearman's Rho test was performed between the stent free cell area and the number and area of ischaemic lesions found after intervention. Adverse events were evaluated.

RESULTS

There was no significant difference in clinical outcome between the three stent groups (Zilver, Cook Europe, Denmark; Smart, Codman, MA; and Wallstent, Stryker, MN, USA). A significant correlation was found between the stent free cell area and the number and area of new ischaemic lesions on DW-MRI (P = 0.023). There were significantly fewer new lesions with an open-cell design (Zilver; 12.76 mm(2) free cell area) than with a closed-cell design (Wallstent; 1.08 mm(2) free cell area).

CONCLUSIONS

Open-cell stent was related to a lower number and area of silent cerebral ischaemic lesions after unprotected CAS. However, clinical outcome, measured by incidence of adverse events and clinical neurologic assessment, was not significantly different between patients with different stent designs.

Non-invasive estimation of pulmonary capillary wedge pressure at rest and during exercise by electrocardiography, phonocardiography and Doppler echocardiography

Non-invasive estimation of the mean pulmonary capillary wedge pressure was accomplished by simultaneous electrocardiographic, phonocardiographic and continuous wave Doppler echocardiographic recordings. The interval from the onset of the QRS complex to the Doppler determined mitral valve closure (Q-MC) and the interval from the phonocardiographic aortic component of the second heart sound to the Doppler determined mitral valve opening (A2-MO) were measured. The non-invasive registrations were carried out simultaneously with direct measurements of the wedge pressure. In an initial group of 22 patients, a significant correlation was observed between the intervals alone and the wedge pressure, r = 0.60, SEE = +/- 6.9 mmHg, p less than 0.01, for the Q-MC interval and r = -0.70, SEE = 6.2 mmHg, p less than 0.001 for the A2-MO interval. A closer correlation was observed between the ratio Q-MC/A2-MO and the measured wedge pressure, r = 0.93, SEE = +/- 3.1 mmHg, p less than 0.001. The linear regression equation, PCW = 19.5 (Q-MC/A2-MO) + 3.0 (mmHg), was applied prospectively to a second group of 23 patients. Again the relationship between estimated and measured wedge pressure was highly significant, r = 0.90, SEE = +/- 3.1 mmHg, p less than 0.001. Twenty-two patients were also studied during an exercise test, and acceptable non-invasive recordings were obtained in 19 of them. The change in estimated wedge pressure during activity related closely to the change in actual wedge pressure, r = 0.80, SEE = +/- 5.7 mmHg, p less than 0.001. A simplified equation suitable for routine clinical practice, PCW = 24 (Q-MC/A2-MO) (mmHg), yielded almost equally accurate estimates of the wedge pressure over a wide range of pressures. The simplicity and reasonable accuracy of Doppler-assisted estimation of the wedge pressure makes it useful in the evaluation and follow-up of patients with suspected cardiac disorders. The method may assist in evaluating the effects of diagnostic or therapeutic procedures, since it is sufficiently sensitive to detect acute directional changes in wedge pressure.

Exercise test in patients with sarcoidosis. The importance of repolarization disturbances

The study population comprises 28 patients with sarcoidosis who all had repolarization disturbances in their exercise ECGs. None of the patients had hypertension or known cardiovascular disease, and all but two were non-smokers. The mean age was 45 years. Exercise test with beta-adrenergic blockade was performed within one month of the first examination. Persisting abnormal ST-T changes in exercise ECGs after beta-blockade were seen in 12 (43%) patients. No significant relationship was found between persisting ST-T changes and age, sex, chest X-ray stage, lung function or working capacity. In an earlier study, we found ST-T abnormalities in exercise ECG in 56 of 127 individuals (44%) in a consecutive 5-year study of patients with newly detected sarcoidosis. From this and the present report we postulate that, in our region, as much as 20% of the patients with newly detected sarcoidosis might have organic myocardial disease, possibly of sarcoid origin, as shown by repolarization disturbances in exercise ECG. If ECG abnormalities in the ST-T region are present in patients with sarcoidosis, exercise ECG with beta-blockade is a simple way of establishing suspicion of organic myocardial lesions. If exercise ECG abnormalities in the ST-T region persist after beta-blockade, careful clinical follow-up is recommended, and, in some patients early steroid therapy should be considered.

Increased prevalence of atherosclerosis in patients with medium term rheumatoid arthritis

OBJECTIVE

To measure the extent of atherosclerosis in patients with rheumatoid arthritis (RA) with a disease duration of considerable length, and in age and sex matched individuals.

METHODS

Thirty-nine patients with RA (30 women, 9 men) with disease onset occurring between 1974 and 1978, and less than 65 years of age at the time of investigation, were enrolled together with 39 sex and age matched controls. Quantitative measurement of intima-media thickness (IMT) and semiquantitative assessment of the presence of plaque were undertaken by B-mode ultrasound of the common carotid artery (CCA-IMT) and the common femoral artery on the right-hand side. Echo Doppler cardiography was performed with an Accuson Aspen. The results were related to disease activity variables and accumulated disease activity, to lipid levels [i.e., cholesterol, high density lipoproteins, low density lipoproteins, triglycerides (TG)], to hemostatic factors [tissue plasminogen activator antigen (tPAag), plasminogen activator inhibitor-1 (PAI-1), von Willebrand factor (vWF)], and to soluble adhesion molecules (sICAM-1 and sE-selectin).

RESULTS

Patients with RA had higher maximal and mean IMT values compared with controls. The difference concerning mean CCA-IMT reached statistical significance in patients with RA and correlated significantly with lipids (cholesterol, LDL, LDL/HDL ratio, TG) and tPAag. The prevalence of plaques, as well as of aortic cusp sclerosis, was higher in RA but only the difference in aortic cusp sclerosis was statistically significant. Patients with plaques had significantly higher levels of lipids (cholesterol, LDL, LDL/HDL ratio) than patients without plaques, while patients with cusp sclerosis had significantly higher cholesterol and TG levels. sICAM-1 was significantly higher both in patients with plaques and in those with aortic cusp sclerosis compared to patients without.

CONCLUSION

Our results suggest an accelerated atherosclerosis in patients with RA that is related mainly to lipid levels.

Expression of inhibitory "killer cell lectin-like receptor G1" identifies unique subpopulations of effector and memory CD8 T cells

T cell and natural killer (NK) cell functions are regulated by triggering of activating and inhibitory cell surface receptors. Here, we have studied the expression profile and predicted inhibitory function of mouse "killer cell lectin-like receptor G1" (KLRG1) on CD8 T cells. KLRG1 was present on 1 - 3 % of adult splenic CD8 cells that expressed CD8alpha beta heterodimers as well as a polyclonal TCR Vbeta repertoire indicative of conventional CD8 cells. The majority of KLRG1(+) CD8 cells belonged to the memory pool as determined by extensive phenotypic marker analysis. Spontaneous IFN-gamma production by approximately 20 % of KLRG1(+) CD8 cells identified them as pro-inflammatory effector cells. In contrast to NK cells, Ly49 and KLRG1 expression on CD8cells was found to be mutually exclusive. Therefore, distinct programs regulate KLRG1 expression in CD8 and NK cells. Finally, we provide evidence that KLRG1 triggering interferes with TCRalpha beta-mediated Ca(++) mobilization and cytotoxicity, raising the possibility that KLRG1 functionally participates in down-regulation of CD8 T cell responses.

Assessment of myocardium at risk in pigs with single photon emission computed tomography and computerized vectorcardiography during transient coronary occlusion

Since myocardium at risk (MAR) is the major prognosticator of final infarct size and outcome in patients with acute myocardial infarction, it is highly desirable to estimate the size of the acutely ischemic myocardium, that is the MAR, in these patients. We assessed MAR size by Tc-99m-sestamibi-SPECT and computerized vectorcardiography using autoradiography as reference method. Transient myocardial ischemia was achieved in 12 pigs by coronary artery occlusion with PTCA catheters. During the procedure, computerized vectorcardiography was continuously recorded. After injection of Tc-99m-sestamibi and gadolinium-153-labelled microspheres, MAR size was estimated by SPECT and post-mortem autoradiography. Different cut-off levels (50-70%) were compared with respect to MAR-SPECT. Tc-99m-sestamibi-SPECT showed a good correlation with autoradiography (r = 0.94). Computerized vectorcardiography showed a good correlation with autoradiography as well as with Tc-99m-sestamibi-SPECT (STC-VM: r = 0.75 and 0.80, respectively, ST-VM: 0.75 and 0.87, respectively). It was found that 1) MAR assessed by Tc-99m-sestamibi-SPECT correlates closely with the autoradiographic reference; 2) a lower cut-off point of 60% of maximum uptake for MAR by Tc-99m-sestamibi-SPECT gives the closest correlation with the autoradiographic reference; and 3) ST-VM and STC-VM correlate well with MAR assessed by Tc-99m-sestamibi-SPECT and autoradiography.

Pulmonary venous blood flow pattern in patients with univentricular hearts following total cavo-pulmonary connection

The objective of the study was evaluation of the pulmonary venous blood flow (PVF) pattern and the influence of ventricular function and atrioventricular valve regurgitation on this flow in patients with univentricular hearts post total cavo-pulmonary connection (TCPC). Transthoracic or transoesophageal echocardiographic studies were performed in 24 children with normal hearts (group A) and in 24 patients with univentricular hearts (group B). Ventricular function and atrioventricular valve regurgitation was semiquantitatively assessed. Systolic/diastolic maximal velocities and velocity time integrals (VTI) were measured from PVF tracings. Ejection fraction was measured by radionuclide angiography in 11 patients. Twelve patients underwent heart catheterization and angiography. In group B the PVF showed a biphasic flow velocity curve. The systolic integrals were smaller and the diastolic integrals were larger than in group A (6.4 vs. 13.0 cm, P = 0.0001, and 13.9 vs. 10.0 cm, P = 0.005). The pulmonary venous systolic flow fraction in 13 patients with an open fenestration and/or atrioventricular valve regurgitation grade 2-3 was significantly lower than in those 11 patients without fenestration and none/small regurgitation (0.19 vs. 0.40, P = 0.05). In conclusion, the PVF pattern in children with univentricular hearts pallitated with TCPC is similar to the PVF pattern found in individuals with biventricular hearts showing a biphasic flow velocity curve despite the absence of pulsatile pulmonary artery flow. The PVF in patients with TCPC-palliated univentricular hearts is influenced by atrioventricular valve regurgitation and fenestration flow.

The utilization of automated ST segment analysis in the determination of myocardial ischemia

Perioperative cardiac morbidity is a recognized complication of anesthesia and surgery. Morbidity includes myocardial infarction, new onset of unstable angina, congestive heart failure, and arrhythmias. Almost one third of all patients undergoing noncardiac surgery may be at increased risk of cardiac complications by virtue of age, coronary artery disease (CAD), or presence of two or more risk factors for CAD. Although postoperative ischemia has been identified as a significant risk factor for morbidity, automated ST segment analysis systems available with the new generation bedside monitors have not been used to identify ischemic episodes in patients recovering from anesthesia. Twenty-eight patients, age 41 to 80 years, were monitored in the postanesthesia care unit for ST segment changes (mean monitoring period, 97 minutes). Four patients had ischemic episodes from 7 to 44 minutes, and two of these patients had subsequent postoperative morbidity. All episodes were clinically silent. Automated ST segment analysis is an easily used technology that shows promise as a means of early detection of clinically silent perioperative myocardial ischemia.

Invasive evaluation of mitral regurgitation: the importance of hemodynamic measurements during exercise

BACKGROUND AND AIMS OF THE STUDY

In patients with mitral regurgitation, left ventricular angiography is usually performed to grade the regurgitation. This is a semi-quantitative method which gives some information related to the regurgitant volume at a certain time. The aim of our study was to evaluate the benefits of invasive hemodynamic examinations during stress. Patients with mitral regurgitation according to Doppler color flow mapping, and regurgitation of no more than grade 2+ according to left ventricular angiography, were of special interest.

METHODS

One hundred and four consecutive patients were examined with transesophageal echocardiography (TEE), left ventricular angiography and cardiac catheterization during rest and during hemodynamic stress.

RESULTS

All patients had mitral regurgitation according to Doppler color flow mapping. Thirty eight patients had a mitral regurgitation of grade 0, 1+ or 2+ according to left ventricular angiography. Of these, seven had a resting v-wave < or = 25 mmHg, and a v wave > or = 50 mmHg during stress. When these seven patients were compared with those with severe grade 3+ and 4+ regurgitation, there was a significant difference between the v-wave at rest (p = 0.02) but no significant difference during stress (p = 0.42).

CONCLUSIONS

Mitral regurgitation is a dynamic lesion, the complete assessment of which cannot be obtained from a single measure during one hemodynamic situation. Additional information from v-wave recordings during hemodynamic stress identified a subgroup of patients who had near-normal pressures at rest, but whose v-wave measurements during stress did not differ significantly from those of patients with severe angiographically assessed regurgitation (grades 3+ and 4+). In patients with only minor mitral regurgitation which is suspected to contribute to their clinical symptoms, the monitoring of invasive hemodynamic parameters during stress is important.

Evaluation of mitral regurgitation by pulmonary venous blood flow patterns. Relation to angiographic and haemodynamic parameters in subgroups of patients

OBJECTIVES

To study the relationship between pulmonary venous systolic flow fraction (PVSFfr) recorded using pulsed Doppler transesophageal echocardiography and angiographic grading and haemodynamic parameters in subgroups of patients with mitral regurgitation.

BACKGROUND

Reversed systolic pulmonary venous flow is a sensitive sign of severe mitral regurgitation. Scarse data are available regarding the effects of atrial fibrillation and coronary artery disease.

METHODS

PVSFfr was calculated as the systolic flow velocity integral divided by the total inflow integral. PVSFfr is negative when systolic flow is dominantly reversed. 111 patients were studied.

RESULTS

PVSFfr < 0 was 91% sensitive for angiographic severe mitral regurgitation (MR) (specificity 75%). In patients with sinus rhythm and without coronary artery disease the sensitivity was 100% and specificity was 86% (n = 25). PVSFfr correlated to angiographic grade (r = -0.63, P = 0.0001), mean PCW (r = -0.63, P = 0.0001), v-wave (r = -0.72, P = 0.0001), systolic blood pressure (r = 0.28, P = 0.003) and left atrial diameter (r = -0.42, P = 0.0001) (n = 111). Stepwise linear regression analysis revealed the v-wave, angiographic grading, left atrial diameter and systolic blood pressure to be independent predictors of PVSFfr. Subgroup analysis revealed a correlation (r = 0.85, n = 25) between angiographic grading and PVSFfr in patients with sinus rhythm without CAD and (r = 0.35, n = 23) in patients with CAD in atrial fibrillation.

CONCLUSIONS

PVSFfr is valuable in assessing mitral regurgitation. In the presence of atrial fibrillation and coronary artery disease the correlation with angiographic grading decreases indicating the dynamic nature of this valvular lesion.

Long term follow up of patients with anterior myocardial infarction complicated by left ventricular thrombus in the thrombolytic era

OBJECTIVES

To examine the appearance and resolution of left ventricular thrombi and to study the relation between thrombus and mortality during long term follow up after anterior myocardial infarction.

DESIGN

Ninety nine consecutive patients were prospectively studied until the last included patient had been followed for one year. Streptokinase and aspirin were used routinely, anticoagulants only after a decision by the attending physician. Echocardiography was performed within 3 d of admission, before discharge, and after one, three, and 12 months.

SETTING

Umeå University Hospital, a teaching hospital in Northern Sweden.

MAIN OUTCOME MEASURES

Left ventricular thrombus, segmental myocardial function, and mortality during follow up.

RESULTS

Thirty patients (30%) had a thrombus on discharge. One month, three months, and 12 months after hospital discharge, the thrombus had resolved in 81%, 84%, and 90% of the patients, respectively. The proportion of resolved thrombi at one month was high irrespective of whether anticoagulants were given (10/11, 91%) or not (12/16, 75%), P = 0.4. New thrombi appeared in 12 patients after discharge and resolution and reapperance of thrombi continued during the follow up period. Patients who developed a thrombus during the hospital stay (n = 44, 44%) had more extensive myocardial dysfunction on discharge (P < 0.001) and significantly higher mortality during the follow up period than those without a thrombus (23% v 7%, P < 0.01).

CONCLUSIONS

With routine thrombolytic and aspirin treatment of anterior myocardial infarction, left ventricular thrombi usually resolve during the first month after hospital discharge. Appearance and resolution of thrombi continue, however, in a significant proportion of the patients during long term follow up. A left ventricular thrombus during the initial hospital stay is associated with high long term mortality.

Left ventricular thrombosis after anterior myocardial infarction with and without thrombolytic treatment

OBJECTIVES

To examine the incidence of left ventricular thrombus in patients with anterior myocardial infarction, with and without streptokinase treatment. To identify predictors of thrombus development.

DESIGN

Consecutive patients prospectively studied during the hospitalized period. Echocardiography was performed within 3 days of admission and before discharge.

SETTING

Umeå University Hospital, a teaching hospital in Northern Sweden.

SUBJECTS

Ninety-nine patients with anterior myocardial infarction of whom 74 were treated with streptokinase.

MAIN OUTCOME MEASURES

Left ventricular thrombus and left ventricular segmental myocardial function.

RESULTS

During the hospital stay, a thrombus developed in 46% (95% confidence interval [CI], 35-57%) of the patients in the thrombolysis group and in 40% (95% CI, 21-59%) of the patients in the non-thrombolysis group. No difference in left ventricular segmental myocardial function was found between the thrombolysis and non-thrombolysis groups at hospital discharge. No embolic events were observed. The occurrence of a left ventricular thrombus at hospital discharge was significantly associated with previous myocardial infarction, peak enzyme levels, left ventricular global and segmental dysfunction and an increased dose of peroral diuretics or use of parenteral diuretics. In a multiple logistic regression model, left ventricular segmental dysfunction was the most important predictor of left ventricular thrombus.

CONCLUSION

Thrombolytic treatment with streptokinase does not prevent the development of a left ventricular thrombus but the risk of embolic complications is low. The left ventricular segmental myocardial score can be used to assess the risk of thrombus development, also, after thrombolysis.

Pulmonary venous systolic flow fraction in patients with mitral regurgitation: transoesophageal echocardiographic findings in relation to haemodynamic and angiographic evaluation

In patients with mitral regurgitation (MR), pulmonary venous systolic flow fraction (PVSFfr) recorded using pulsed Doppler transoesophageal echocardiography (TEE) was compared with PVSFfr in normal subjects, to angiographic grading and to haemodynamic parameters. PVSfr was calculated as the systolic flow velocity integral divided by total inflow integral. PVSfr is negative when systolic flow is reversed. Forty patients with MR were studied. PVSFfr < 0 was 100% sensitive for angiographic severe MR (specificity 83%). In 35 patents heart rate differed by 10 bpm or less between TEE and cath, either at rest or during stress. PVSFfr was correlated with angiographic grade (r = -0.69, P < 0.0001), with mean PCW (r = -0.61, P < 0.0001), with the v-wave (r = -0.72, P < 0.0001), with systolic blood pressure (r = 0.48, P < 0.005) and with left atrial diameter (r = -0.52, P < 0.005). Stepwise forward multiple linear regression analysis revealed the v-wave, angiographic grading and systolic blood pressure to be independent predictors of PVSFfr. PVSFfr differed in normal subjects, patients with 0-2+ and patients with 3-4+ regurgitation. PVSFfr is a valuable index in assessing mitral regurgitation. This index may be less dependent on equipment and operator than colour flow imaging.

Experimental studies comparing iohexol and 51Cr-EDTA for glomerular filtration rate measurements

The total plasma clearance as well as the renal clearance of iohexol were evaluated for determination of the glomerular filtration rate (GFR) in 16 anesthetized pigs. The iohexol levels in urine and plasma were measured by X-ray fluorescence. The total plasma clearance of 1 and 4 ml/kg b.w. of iohexol 300 mg I/ml was compared to the simultaneously as well as nonsimultaneously calculated total plasma clearance of 51Cr-EDTA. The total plasma clearance of 51Cr-EDTA and of iohexol turned out to be equal and independent of the injected dose of iohexol. The injected dose did not have any effect on the renal clearance of iohexol either. It is concluded that iohexol and 51Cr-EDTA are similar as marker substances for determination of the GFR.

Anaesthesia for abdominal aortic surgery in patients with coronary artery disease, Part II: Effects of nitrous oxide on systemic and coronary haemodynamics, regional ventricular function and incidence of myocardial ischaemia

This study examines the effects of nitrous oxide on haemodynamics, anterior left ventricular (LV) function and incidence of myocardial ischaemia in abdominal vascular surgical patients with coronary artery disease. Forty-seven patients were randomly assigned to isoflurane-fentanyl anaesthesia with nitrous oxide-oxygen vs air-oxygen (control). Systemic and coronary haemodynamics, 12-lead ECG, LV anterior wall motion by cardiokymography (CKG) and myocardial lactate balance were recorded at four intervals: before and during anaesthesia and 10 and 30 minutes into surgery. Systemic haemodynamics were controlled by anaesthetic dose, and, when insufficient, by i.v. nitroglycerine (NG) in case of LV failure (PCWP > 18 mmHg) and by phenylephrine during hypotension. We found that nitrous oxide was associated with greater need for i.v. nitroglycerin (patients: P = 0.031, episodes P = 0.005) and more myocardial ischaemia (patients P = 0.012, episodes P = 0.001) despite systemic and coronary haemodynamics comparable to the control group. We conclude that nitrous oxide, known to have both sympathomimetic and cardiodepressive actions, produced cardiodepression in the face of sympathetic stimulation. Our study design did not allow to conclude if myocardial ischaemia was the consequence of increased wall stress or a reason for the observed LV dysfunction. The higher incidence of introperative myocardial ischaemia and need for NG did not cause increased cardiac morbidity.

Simultaneous urography and determination of glomerular filtration rate. A comparison of total plasma clearances of iohexol and 51Cr-EDTA in plegic patients

The total plasma clearance of iohexol at urography and 51Cr-EDTA was compared in 31 patients with di- or tetraparesis. A reference 51Cr-EDTA clearance was also performed 24 hours prior to the urography. The GFR was calculated from one, 2 or 4 plasma samples collected 180, 210, 240 and 270 min after the injection. An X-ray fluorescence analyzer was used for the analysis of iohexol in plasma as well as the contrast medium clearance calculations. It was shown that single or multiple sample clearance of iohexol and 51Cr-EDTA were equivalent methods for measurement of the GFR. The GFR was not affected by iohexol in a dose routinely used for urography. It was concluded that the patient comfort is improved if 51Cr-EDTA clearance is replaced by contrast medium clearance in association with urography.

Computer-assisted evaluation of dipyridamole thallium-201 SPECT in patients with aortic stenosis

Dipyridamole SPECT detects significant coronary artery disease (CAD) in patients without aortic stenosis. This study was done to establish normal 201Tl distribution limits in patients with aortic stenosis and to apply these normal limits to patients with aortic stenosis and angiographically significant CAD (> or = 75% area reduction).

METHODS

Fifty-two patients (mean age 68 yr; mean valve area 0.67 cm2) were examined with 201Tl SPECT after dipyridamole infusion (0.56 mg/kg during 4 min). After tomographic reconstruction, basal, mid-ventricular and apical short-axis slices were selected. The highest activity in each six-degree segment was normalized to the maximal activity of each slice.

RESULTS

Significant CAD was found in 24 patients. Five patients without CAD, but with localized hypokinesia or left bundle-branch block, were excluded from the reference group which finally consisted of 16 patients. Sensitivity for CAD was 88% when the lowest relative activity in each segment was used as the lower limit of normal. With -2 s.d. and -2.5 s.d. curves the sensitivity was 83% and 75%, respectively. Gender-specific limits were not used. Nonsignificant CAD was found in seven patients (< 75% stenoses).

CONCLUSIONS

This study presents the normal distribution of 201Tl uptake for patients with aortic stenosis, using dipyridamole SPECT. The range method had the highest sensitivity for detection of significant CAD.

Significance of simple renal cysts and percutaneous cyst puncture on renal function

Renal function was investigated in 17 patients with simple renal cysts. Single kidney glomerular filtration rate was estimated by gamma camera renography with 99mTc-DTPA before, 5 days and 6 months after percutaneous puncture and evacuation of the cysts. Prior to the puncture and evacuation, the only negative effects on renal function noted were signs of moderate obstruction of the renal outflow in 2 patients. Percutaneous puncture with evacuation of the cystic fluid did not change the renal function significantly. It was concluded that simple renal cysts do not have any functional consequences nor does percutaneous puncture and evacuation of the cysts.

Quantitative assessment of aortic regurgitation by combined two-dimensional, continuous-wave and colour flow Doppler measurements

The width of the regurgitant jet at the aortic valve plane, i.e. the core flow diameter, the ratio of the jet width to the left ventricular outflow diameter, the regurgitant volume and regurgitant fraction were determined using two-dimensional, continuous wave and colour flow Doppler echocardiography. The relationship between the non-invasive measurements and semiquantitative angiographic grading of the regurgitant flow (1 + to 4+) was examined in a primary group of 20 patients with chronic aortic regurgitation. Cut-off points for the non-invasive measurements were selected so as to separate patients with mild or moderate regurgitation (1+ or 2+) from patients with moderately severe or severe regurgitation (3+ or 4+). These cut-off points were prospectively applied in a new group of 35 patients with aortic regurgitation to predict the angiographic grading. Jet width correctly predicted the angiographic grading in 86% of cases, the ratio of the jet width to the outflow diameter in 83% of cases, the regurgitant volume in 86% of cases and the regurgitant fraction in 91% of cases. We conclude that the severity of aortic regurgitation as determined by angiographic grading can be estimated with reasonable accuracy by non-invasive techniques based on colour flow imaging.

Quantification of left to right shunts by echo Doppler cardiography in patients with ventricular septal defects

Thirty-one patients with ventricular septal defect were evaluated with Echo Doppler cardiography and colour flow mapping. The ventricular septal defect area was estimated by measurement of the jet diameter by colour flow mapping. The ventricular septal defect flow was calculated as the product of the cross-sectional area of the ventricular septal defect and the velocity time integral of flow through the defect. In ten patients the diameter obtained by colour flow mapping was compared with the diameter obtained at angiography, r = 0.88 (SD = 0.14 cm). The aortic flow was calculated as the product of left ventricular outflow tract cross-sectional area and the corresponding velocity time integral. QP/QS ratio was estimated as (ventricular defect flow + aortic flow)/aortic flow and compared to estimates by a radionuclide or oximetric method. A correlation of r = 0.95 (SD = 0.23) was found.

Surfactant protein-A in bronchoalveolar lavage fluid from neonates with RDS on conventional and high-frequency oscillatory ventilation

Surfactant protein-A (SP-A) was measured in bronchoalveolar lavage (BAL) samples from ventilated neonates in order to study the concentration of SP-A with regard to: 1) high-frequency oscillatory ventilation (HFOV) vs. conventional mechanical ventilation (CMV); 2) the postnatal course and ontogeny of SP-A; and 3) the correlation with measurements of pulmonary function. Patients on HFOV had markedly lower BAL SP-A concentrations on days 1 and 2 compared to those on CMV, which may indicate influence of mode of ventilation on surfactant metabolism. The SP-A concentrations increased postnatally concurrent with resolution of acute respiratory distress syndrome. Finally, there were only weak correlations between BAL SP-A concentration and dynamic lung compliance and oxygen requirement.

Doppler echocardiographic assessment of the valve area in patients with atrioventricular valve stenosis by application of the continuity equation

The orifice area was non-invasively assessed in 19 patients with mitral or mitral and tricuspid stenosis by combined cross-sectional and Doppler echocardiography. Stroke volume was calculated as the product of aortic or pulmonic cross-sectional area and the time velocity integral of the flow across that valve, and the stenotic valve area was obtained as the stroke volume divided by the time velocity integral of the stenotic valve. In addition, the mitral valve area was estimated by the pressure half-time method of Hatle et al. The non-invasive determinations were compared with those calculated by the Gorlin formula at cardiac catheterization. The valve area obtained by combined cross-sectional and Doppler echocardiography showed a close correlation with the Gorlin area, r = 0.90, SEE = 0.13 cm2, n = 20. In contrast, the valve area estimated by the pressure half-time method showed only a moderate correlation with the Gorlin area, r = 0.68, SEE = 0.38 cm2, n = 18, and estimates by this method tended to significantly overestimate the Gorlin area. In conclusion, non-invasive valve area determinations based on combined cross-sectional and Doppler echocardiography can be used to accurately quantify the severity of the lesion in patients with atrioventricular valve stenosis, while determinations by the pressure half-time method may show errors of a magnitude that limits its clinical applicability.

Reassessment of valve area determinations in mitral stenosis by the pressure half-time method: impact of left ventricular stiffness and peak diastolic pressure difference

Estimation of the orifice area is of major importance in the timing of valve dilation or surgery in patients with mitral stenosis. Determination of the area has traditionally been accomplished at cardiac catheterization by the Gorlin equation. The valve area can also be estimated noninvasively with Doppler echocardiographic measurements of the pressure half-time, which is inversely proportional to the area. This method has gained widespread acceptance, but its accuracy has recently been questioned and factors other than reduction of orifice area appear to modify the pressure half-time. In the present study, the influence of left ventricular stiffness (defined as diastolic pressure rise per milliliter of mitral flow) and peak atrioventricular pressure difference on the pressure half-time was examined both in a hydraulic model and by review of data from 35 patients with mitral stenosis. Left ventricular stiffness less than 0.13 mm Hg/ml was considered normal. In the model study, the orifice area correlated only moderately with inverted pressure half-time (1/PHT) (r = 0.67). By multiple linear regression, inverted pressure half-time was shown to be dependent on valve area, chamber stiffness and peak pressure difference (R = 0.89), area and stiffness being most important (R = 0.85). In the clinical study, an increased ventricular stiffness was found in 22 of the 35 patients. The pressure half-time method overestimated the Gorlin-derived area by an average of 72% in these patients compared with only 10% in 13 patients with normal stiffness (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Noninvasive determination of the valvar area in aortic valve disease by Doppler echocardiography and radionuclide angiography

To assess the severity of outlfow obstruction in patients with aortic valve disease, the aortic valvar area was noninvasively determined in 22 patients with isolated aortic stenosis or combined stenosis and regurgitation. The ejection time (ET), maximal velocity (Vmax), and systolic velocity integral (SVI) of the aortic flow was obtained by continuous wave Doppler ultrasound. Left ventricular stroke volume (SV) was determined by radionuclide angiography, using a counts-based nongeometric technique with individual attenuation correction. Aortic valve area (AVA) was calculated using a modified Gorlin formula; AVA = SV/(71.2 X ET X Vmax), and also by dividing the stroke volume by the systolic velocity integral; AVA = SV/SVI. The two noninvasive determinations correlated closely with the valve areas obtained by invasive measurements; r = 0.95, SEE = +/- 0.13 cm2 by the modified Gorlin formula, and r = 0.94, SEE = +/- 0.14 cm2 by the integration method. The two noninvasive calculations showed almost uniform results; r = 0.98, SEE = +/- 0.09 cm2. In conclusion, aortic valve area can be determined with reasonable accuracy by combining Doppler echocardiography and radionuclide angiography. This noninvasive approach may reduce the need for invasive measurements in patients with suspected aortic valve disease. In addition, radionuclide angiography provides important information about left ventricular function.

Technetium-99m pyrophosphate single-photon emission computed tomography of the heart in familial amyloid polyneuropathy

A patient with familial amyloid polyneuropathy and congestive heart failure underwent myocardial imaging using technetium-99m pyrophosphate. Planar scintigraphy showed an intense, diffuse biventricular uptake of the radiotracer. Single-photon emission computed tomography demonstrated an unevenly distributed uptake of the isotope. The greatest activity corresponded to regions with marked echocardiographic changes. Emission tomography may aid in assessing the degree and distribution of the infiltrative lesions in cardiac amyloidosis.

Non-invasive estimation of the mean pressure difference in aortic stenosis by Doppler ultrasound

The mean pressure difference across the valve in aortic stenosis is an indicator of the severity of the obstruction to flow. Non-invasive determination of the mean pressure gradient by Doppler ultrasonography is, however, complicated by the squared relation between instantaneous velocities and pressure differences. The validity of a new simple formula for calculation of the mean pressure difference from the peak pressure difference was evaluated in 26 patients with aortic stenosis. The formula is: delta pmean = 0.64 delta ppeak, where delta pmean is the mean pressure gradient and delta ppeak the peak pressure gradient. There was a close correlation between the mean pressure differences determined by application of the formula to the peak pressure differences measured at catheterisation and the mean pressure differences obtained by planimetry (r = 0.97, SEE = 4.7 mm Hg). The correlation between mean pressure differences determined by continuous wave Doppler ultrasound and the formula and those measured by planimetry was also close (r = 0.91, SEE = 7.6 mm Hg) and only three patients showed a difference between the two methods of greater than 10 mm Hg. The new formula is a simple and reliable means of estimating the mean pressure difference from Doppler recordings and it facilitates the comparison of Doppler and catheterisation data.

Disturbances of cardiac rhythm and conduction in familial amyloidosis with polyneuropathy

Sixteen consecutive patients with familial amyloidosis with polyneuropathy of varying duration and severity underwent 24 hour ambulatory electrocardiographic monitoring. A high incidence of sinus node dysfunction, supraventricular and ventricular arrhythmias, and disturbances of atrioventricular conduction was found. Considerably more arrhythmias and disturbances of conduction were detected by long term electrocardiographic monitoring than by conventional 12 lead electrocardiograms. During a follow up period of three to 14 months five patients needed treatment by a pacemaker, three of them because of symptomatic complete heart block, one because of second degree heart block with heart failure, and one because of symptomatic dysfunction of the sinus node. The tachyarrhythmias did not require specific treatment. Long term electrocardiographic monitoring is a useful adjunct in the evaluation of patients with familial amyloidosis with polyneuropathy as it may detect otherwise unrecognised symptomatic disturbances of heart rhythm. The results may be valid also for other forms of amyloidosis involving the heart.