Myocardial viability as a determinant of the ejection fraction response to carvedilol in patients with heart failure (CHRISTMAS trial): randomised controlled trial

BACKGROUND

The improvement in left-ventricular ejection fraction (LVEF) in response to beta blockers is heterogeneous in patients with heart failure due to ischaemic heart disease, possibly indicating variations in the myocardial substrate underlying left-ventricular dysfunction. We investigated whether improvement in LVEF was associated with the volume of hibernating myocardium (viable myocardium with contractile failure).

METHODS

We did a double-blind, randomised trial to compare placebo and carvedilol for 6 months in individuals with stable, chronic heart failure due to ischaemic left-ventricular systolic dysfunction. We enrolled 489 patients, of whom 387 were randomised. Patients were designated hibernators or non-hibernators according to the volume of hibernating myocardium. The primary endpoint was change in LVEF, measured by radionuclide ventriculography, in hibernators versus non-hibernators, on carvedilol compared with placebo. Analysis was by intention to treat.

RESULTS

82 patients dropped out of the study because of adverse events, withdrawal of consent, or failure to complete the investigation. Thus, 305 (79%) were analysed. LVEF was unchanged with placebo (mean change -0.4 [SE 0.9] and -0.4 [0.8] for non-hibernators and hibernators, respectively) but increased with carvedilol (2.5 [0.9] and 3.2 [0.8], respectively; p<0.0001 compared with baseline). Mean placebo-subtracted change in LVEF was 3.2% (95% CI 1.8-4.7; p=0.0001) overall, and 2.9% (0.7-5.1; p=0.011) and 3.6% (1.7-5.4; p=0.0002) in non-hibernators and hibernators, respectively. Effect of hibernator status on response of LVEF to carvedilol was not significant (0.7 [-2.2 to 3.5]; p=0.644). However, patients with more myocardium affected by hibernation or by hibernation and ischaemia had a greater increase in LVEF on carvedilol (p=0.0002 and p=0.009, respectively).

INTERPRETATION

Some of the effect of carvedilol on LVEF might be mediated by improved function of hibernating or ischaemic myocardium, or both. Medical treatment might be an important adjunct or alternative to revascularisation for patients with hibernating myocardium.

Left ventricular preload and function during graded haemorrhage and retranfusion in pigs: analysis of arterial pressure waveform and correlation with echocardiography

BACKGROUND

Arterial pressure waveform analysis is a new method for assessment of cardiac preload. Despite the close correlation of parameters derived by its use with the degree of blood loss, their relationship with more precise estimates of cardiac preload remains controversial.

METHODS

Systolic pressure variation (SPV), delta up (dUp), and delta down (dDown), which are the changes in the arterial blood pressure (BP) during mechanical ventilation, were measured during graded haemorrhage and retransfusion in seven pigs under light halothane anaesthesia, and compared with changes in cardiac filling pressures and left ventricular end-diastolic volume (LVEDV), measured by echocardiography.

RESULTS

Significant changes in preload parameters and stroke volume (SV) but not in BP and heart rate occurred. SPV, dDown, and cardiac filling pressures correlated significantly with LVEDV. Following retransfusion, LVEDV returned to baseline values but the SV and left ventricular ejection fraction were significantly low. This deterioration in myocardial performance was associated with elevated dUp.

CONCLUSIONS

During mechanical ventilation, dDown and the SPV may serve as minimally invasive indicators of preload. The retransfusion stage that follows significant blood loss may be associated with deterioration in LV function.

Insulin-like growth factor I and II preserve myocardial structure in postinfarct swine

BACKGROUND

Insulin-like growth factors (IGF) I and II improve myocardial function after coronary occlusion in different animal models.

OBJECTIVES

To investigate the mechanism of improved myocardial function after administration of IGF-I or IGF-II in acute myocardial infarction.

METHODS

Female pigs (mean (SD) weight 25 (5) kg) were subjected to acute myocardial infarction by microembolisation with 75-150 micrometer affigel blue beads. The beads contained and slowly released 150 microgram/pig of IGF-I (n = 6), IGF-II (n = 6), or pig albumin (n = 6). Echocardiography, perfusion imaging, and haemodynamic measurements were performed before infarction and during four weeks after infarction. Regional wall motion of different left ventricular segments was scored semiquantitatively on the basis of a three point scoring system, from normal = 0 to dyskinesia = 3. Serum cardiac troponin I concentration was measured before, immediately after, and three hours after the infarct. Excised hearts were analysed for actin, desmin, blood vessel density, and DNA laddering within the infarct, border, and normal myocardial areas.

RESULTS

Myocardial function of the infarct related area improved significantly during the four weeks of follow up in both the IGF groups (p = 0.01). Myocardial perfusion, heart rate, and blood pressure were similar in all the animals during the study. Treated animals had lower serum cardiac troponin I concentration (p = 0.001), more actin in the border area (p = 0.01) and infarct area (p = 0.0001), and reduced DNA laddering in the infarct area compared with the controls (p < 0.05). IGF groups had more blood vessels in the border area (p = 0.04) and the infarct area (p = 0.003).

CONCLUSIONS

Both types of IGF improved myocardial function and the improvement was associated with preservation of myocardial structure. IGF-I was more effective than IGF-II.

Retrograde embolism and atherosclerosis development in the human thoracic aorta: are the fluid dynamics explanations valid?

The mechanisms of atherosclerosis development in the thoracic aorta is miscellaneous and still only partially understood. The marked variability of the sites of deposition of atherosclerotic plaques in the aorta could not be clarified based solely on the risk-factors theory of atherosclerosis. The sites of deposition of atherosclerotic plaques are considered to be affected by blood-flow patterns that cause areas of altered shear stress on the aortic wall. Close relations between protruding aortic plaques (PAP), stroke and peripheral emboli were established. The analysis of PAP distribution and motion to characterize atherogenesis in the human thoracic aorta and the pathogeneses of embolic events was performed. We concluded that protruding aortic plaques and markers of relative aortic flow instability (occurrences of vortices) are predominantly noticed in the human arch and in the descending aorta, whereas the ascending aorta showed lesser prevalence of atheromatosis. Reversal and rotational blood-flow in the thoracic aorta most likely exist in all patients with systemic emboli and mobile protruding aortic atheromas. Therefore, retrograde cerebral embolism from distal aortic plaques is conceivable.

Tezosentan (an intravenous endothelin receptor A/B antagonist) reduces peripheral resistance and increases cardiac power therefore preventing a steep decrease in blood pressure in patients with congestive heart failure

OBJECTIVE

This study investigated the effect of tezosentan (an intravenous endothelin-1 receptor antagonist) on vascular resistance and cardiac function and determined the dose response in patients with stable congestive heart failure (CHF) due to left ventricular systolic dysfunction.

METHODS

In a double-blind fashion, tezosentan or placebo were administered in ascending doses (5, 20, 50, 100 mg h(-1)) to 38 CHF (NYHA class III) patients with ejection fraction <or=35%, cardiac index <or=2.7 l min(-1) m(-2) and pulmonary capillary wedge pressure >or=15 mmHg. Systemic vascular resistance index (SVRi) was estimated as mean arterial blood pressure [(MAP-right atrial pressure)/cardiac index (CI)]. Cardiac function was assessed as cardiac power index (Cpi), calculated as pressure x flow (MAP x CI), where MAP represents pressure and CI represents cardiovascular flow.

RESULTS AND DISCUSSION

Compared to the placebo, tezosentan induced a dose-dependent decrease in SVRi (-32%), an increase in Cpi (+20%) and a small decrease in MAP (-9%). By contrast, patients treated with nitrate vasodilators or nesiritide (a natriuretic peptide) showed a decrease in SVRi not accompanied by a significant increase in Cpi leading to a steep decrease in MAP.

CONCLUSIONS

The use of Cpi in the assessment of the hemodynamic effects of tezosentan, provides a useful alternative characterization of the complex influences of vasodilators on cardiac function in patients with CHF.

Caseous calcification of the mitral annulus: a neglected, unrecognized diagnosis

BACKGROUND

Mitral annular calcification is a common echocardiographic finding. Caseous calcification is a rare variant seen as a large mass with echolucencies that resembles a tumor, occasionally resulting in exploratory cardiotomy. The aim of this study was to assess the prevalence of caseous calcification of the mitral annulus, to evaluate patient characteristics and the echocardiographic variables for diagnosing this entity, and to describe the clinical outcome on follow-up of such patients.

METHODS

Caseous calcification was defined as a large, round, echo-dense mass with smooth borders situated in the periannular region, with no acoustic shadowing artifacts and containing central areas of echolucencies resembling liquefaction. Eighteen patients were diagnosed by 2-dimensional echocardiography as having caseous calcification of the mitral annulus. One had calcification of the tricuspid annulus. Nine patients underwent transesophageal echocardiographic studies.

RESULTS

A typical finding of a round, sometimes semilunar, large, echo-dense, soft mass with central echolucencies seen on both transthoracic and in particular transesophageal echocardiography, resembling a periannular mass, was demonstrated. The mass was posteriorly located in all mitral patients. Transesophageal echocardiography added limited information. Three patients underwent mitral valve replacement. The operative findings were a solid mass adherent to the posterior portion of the mitral valve. Sectioning revealed a toothpaste-like, white, caseous material. Sixteen (84%) patients were treated conservatively. On follow-up of 3.8 +/- 2.4 years, 4 patients died of unrelated causes.

CONCLUSION

The characteristic appearance of a large, soft, echo-dense mass containing central areas of echolucencies resembling liquefaction at the posterior periannular region of the mitral valve on 2D echocardiography is compatible with the diagnosis of caseous abscess. Such a finding should not be confused with a tumor. Transesophageal echocardiography does not appear to contribute to the diagnosis. This rather impressive lesion appears to carry a benign prognosis.

Shu 508 A (Levovist)-enhanced Doppler echocardiography improves the assessment of valvular heart disease

OBJECTIVE

To investigate whether intravenous injection of SHU 508 A improves the diagnostic accuracy of Doppler echocardiography in the assessment of valvular pathologies.

METHODS AND RESULTS

One hundred and twenty-five consecutive patients with valvular pathology (aortic stenosis, n = 48; aortic regurgitation, n = 20; mitral stenosis, n = 21; and mitral regurgitation, n = 36) and diagnostically insufficient Doppler signal were enrolled in this multicenter study. The severity of valvular pathology was graded on a four-point scale using unenhanced and contrast-enhanced Doppler echocardiography as well as cardiac catheterization. Agreement with cardiac catheterization findings increased from 63% using the unenhanced examination to 73% using the contrast-enhanced Doppler examination. Grading was possible in all patients using SHU 508 A, whereas the unenhanced Doppler examination remained inconclusive in six patients. The weighted kappa coefficient between contrast-enhanced Doppler and cardiac catheterization for all diagnoses was 0.76 as compared to 0.68 between unenhanced Doppler and cardiac catheterization. Agreement was especially improved in aortic stenosis (kappa 0.69 unenhanced vs 0.81 contrast-enhanced) and in aortic regurgitation (kappa 0.45 unenhanced vs 0.75 contrast-enhanced). Patients with mitral stenosis and mitral regurgitation experienced less improvement.

CONCLUSIONS

In case of an inconclusive unenhanced Doppler echo study, the administration of a left heart contrast agent should be considered. SHU 508 A is especially useful in improving the severity grading of aortic stenosis and aortic regurgitation, while grading of mitral stenosis and mitral regurgitation is less improved.

Dobutamine echocardiography in patients with aortic stenosis and left ventricular dysfunction: predicting outcome as a function of management strategy

STUDY OBJECTIVE

To prospectively address the question whether the assessment of valvular hemodynamics and myocardial function during low-dose dobutamine infusion can guide decision making in patients with aortic stenosis and left ventricular (LV) dysfunction.

PATIENTS AND MEASUREMENTS

Twenty-four patients with aortic stenosis and LV dysfunction (mean ejection fraction, 28%; New York Heart Association class, II to IV) were studied by dobutamine echocardiography assessing mean pressure gradient, aortic valve area, and aortic valve resistance. Patients were prospectively divided into severe and nonsevere aortic stenosis groups according to the response of the valve area to the augmentation of systolic flow. The clinical decision was considered to be concordant with the results of dobutamine echocardiography, when patients with severe aortic stenosis and preserved contractile function were referred by a specialist for aortic valve replacement and when patients with nonsevere aortic stenosis were not. Patients were observed for up to 3 years.

RESULTS

All eight patients with severe aortic stenosis who were referred for surgery survived and had good cardiovascular outcomes, and six of eight patients who were not initially referred for surgery had poor outcomes, including heart failure and sudden cardiac death. The eight patients with nonsevere aortic stenosis did comparatively well without valve replacement. Cardiac death or pulmonary edema occurred in 4 of 16 patients (25%) when the clinical decision was concordant with the results of the dobutamine echocardiogram and occurred in 6 of 8 patients (75%) when the clinical decision was discordant (p = 0.019 [chi(2) test]).

CONCLUSION

Patients with aortic stenosis, LV dysfunction, and relatively low gradients have better outcomes when management decisions are based on the results of dobutamine echocardiograms. Those patients identified as having severe aortic stenosis and preserved contractile reserve by dobutamine echocardiography should undergo surgery, while patients identified as having nonsevere aortic stenosis can be managed conservatively.

Pulmonary edema: new insight on pathogenesis and treatment

Pulmonary edema is one of the most serious and life-threatening situations in emergency medicine. Lately it has become apparent that in most cases pulmonary edema is not caused by fluid accumulation but rather fluid redistribution that is directed into the lungs because of heart failure. Based on a series of recently published studies, we propose that often the pathogenesis of pulmonary edema is related to a combination of marked increase in systemic vascular resistance superimposed on insufficient systolic and diastolic myocardial functional reserve. This resistance results in increased left ventricular diastolic pressure causing increased pulmonary venous pressure, which yields a fluid shift from the intravascular compartment into the pulmonary interstitium and alveoli, inducing the syndrome of pulmonary edema. Therefore, the emphasis in treating pulmonary edema has shifted from diuretics (ie, furosemide) to vasodilators (ie, high-dose nitrates) combined with noninvasive positive airway pressure ventilation and rarely inotropes. New classes of drugs that are currently being investigated for treating decompensated heart failure such as natriuretic peptides, calcium promoters, and endothelin antagonist are also being assessed for treating pulmonary edema. This review will explore this new hypothesis put forward to explain the pathogenesis of pulmonary edema and the evolving management strategies.

Fluid dynamics and atherosclerosis development in the human thoracic aorta: a transesophageal echocardiographic evaluation of protruding aortic plaque distribution and motion

The pathogeneses of atherosclerosis in the thoracic aorta is heterogeneous and still incompletely elucidated. Protruding aortic plaques (PAP), reliable markers of atherosclerosis development and extension, could be easily identified by transesophageal echocardiography (TEE). A close relation between atherosclerosis development in the thoracic aorta, stroke and peripheral emboli were established. The purpose of this study was to use PAP distribution and motion on TEE to characterize atherogenesis in the human thoracic aorta. Out of 569 consecutive patients (age range 18-83 years), 108 were referred for TEE to evaluate recent embolism (Group I). The remaining 461 patients were referred for TEE for reasons unrelated to embolism (Group II). The plaque thickness was measured perpendicularly to the aortic wall. In the subgroup of patients with multiple mobile lesions, multiple vortices were suggested to be present when simultaneous rotations in different directions were found. The presence of a fixed PAP was associated with a statistically significant, albeit moderate, increase in the risk for embolism (adjusted odds ratio 4.1). The presence of mobile lesions was linked to an abrupt augmentation in this risk (adjusted odds ratio 30.1). Among the 35 patients in Group I there were 69 PAP: 8 (12%) in the ascending, 28 (41%) in the arch and 33 (48%) in the descending aorta. A total of 34 mobile lesions was detected: 1 (one patient) in the ascending aorta, 15 (10 patients) in the arch and 18 (11 patients) in the descending aorta. There was no significant difference between the arch and the descending aorta regarding the frequency of the plaques in these regions, whereas the ascending aorta presented the lowest prevalence for atheromatosis. Diastolic retrograde and rotational flows were observed in all patients. There were 16 multiple mobile PAP in 6 patients: in all these cases simultaneous rotations of mobile aortic plaques (MAP) in different directions (highly suggestive for the presence of multiple vortices and significant flow instability) were found in the arch and the descending but not the ascending aorta. Protruding aortic plaques and signs of relative aortic flow instability (presence of vortices) are mainly observed in the human arch and in the descending aorta, whereas the ascending aorta presented the lowest prevalence for atheromatosis. This issue may have significant implications in the study of atherosclerosis development in the human thoracic aorta and the pathogeneses of embolic events.

Retrograde flow in the thoracic aorta in patients with systemic emboli: a transesophageal echocardiographic evaluation of mobile plaque motion

STUDY OBJECTIVES

Blood flow in the aorta is complex and incompletely characterized. Mobile aortic plaques (MAPs), moving freely with the pulsatile aortic flow, in fact represent natural tracers that reflect the flow pattern itself. Our aim was to use MAP motion on transesophageal echocardiography (TEE) in order to characterize flow patterns in the atheromatous thoracic aorta of patients with systemic emboli.

DESIGN AND PATIENTS

The study group was recruited from 250 patients referred for TEE to evaluate recent embolism. Among them, 22 patients (14 men and 8 women; mean +/- SD age, 66.3 +/- 7.2 years; 16 patients with cerebrovascular and 6 patients with peripheral emboli) with MAPs of > or = 3 mm in length formed the study group. The longest amplitudes of three spatial components of mobile lesion motions were measured: x (antegrade/retrograde [A/R]), y (up/down [U/D], and z (right/left [R/L]).

RESULTS

A total of 33 mobile lesions were detected: 3 in the ascending aorta (1 patient), 13 in the arch (10 patients), and 17 in the descending aorta (11 patients). The length of mobile plaque components ranged from 3 to 13 mm; amplitudes of A/R, U/d, R/L, and retrograde flow motions ranged from 3 to 26 mm, from 1 to 16 mm, from 1 to 17 mm, and from 1 to 13 mm, respectively. Systolic rotational motion was clockwise in six patients (27%), counterclockwise in five patients (23%), incomplete (semicircle) in six patients (27%), and alternate clockwise/counterclockwise in five patients (23%). Diastolic rotational motion was clockwise in 5 patients (23%), counterclockwise in 6 patients (27%), and incomplete (semicircle) in 11 patients (50%). There were 18 multiple MAPs in seven patients: in all these cases, simultaneous rotations of MAP in different directions (as a marker for the presence of multiple vortices) were found. In nine patients with cerebral embolism, MAPs on the distal part of aortic arch solely were found; in five of them, all alternative potential sources of stroke were excluded. Therefore, retrograde cerebral embolism from distal aortic plaques in these patients is highly probable.

CONCLUSIONS

Retrograde and rotational blood flow in the thoracic aorta probably exists in all patients with systemic emboli and mobile protruding aortic atheromas. Therefore, retrograde cerebral embolism from distal aortic plaques is theoretically possible.

Impact of atrioventricular compliance on pulmonary artery pressure in mitral stenosis: an exercise echocardiographic study

BACKGROUND

The decay of the pressure gradient across a stenotic mitral valve is determined by the size of the orifice and net AV compliance (C(n)). We have observed a group of symptomatic patients, usually in sinus rhythm, characterized by pulmonary hypertension (particularly during exercise) despite a relatively large mitral valve area by pressure half-time. We speculated that this discrepancy was due to low atrial compliance causing both pulmonary hypertension and a steep decay of the transmitral pressure gradient despite significant stenosis. We therefore tested the hypothesis that C(n) is an important physiological determinant of pulmonary artery pressure at rest and during exercise in mitral stenosis.

METHODS AND RESULTS

Twenty patients with mitral stenosis were examined by Doppler echocardiography. C(n), calculated from the ratio of effective mitral valve area (continuity equation) and the E-wave downslope, ranged from 1.7 to 8.1 mL/mm Hg. Systolic pulmonary artery pressure (PAP) increased from 43+/-12 mm Hg at rest to 71+/-23 mm Hg (range, 40 to 110 mm Hg) during exercise. There was a particularly close correlation between C(n) and exercise PAP (r=-0.85). Patients with a low compliance were more symptomatic (P<0.025). Catheter- and Doppler-derived values for C(n), determined in 10 cases, correlated well (r=0.79).

CONCLUSIONS

C(n), which can be noninvasively assessed, is an important physiological determinant of PAP in mitral stenosis. Patients with low C(n) represent an important clinical entity, with symptoms corresponding to severe increases in PAP during stress echocardiography.

Prognostic significance of mild mitral regurgitation by color Doppler echocardiography in acute myocardial infarction

Mitral regurgitation (MR) complicating acute myocardial infarction (AMI) is associated with increased mortality. The prognostic significance of only mild MR detected by echocardiography in patients with AMI is unknown. This study assessed the long-term risk associated with mild MR detected by color Doppler echocardiography within the first 48 hours of admission in 417 consecutive patients with AMI. No MR was detected in 271 patients (65%), mild MR was seen in 121 patients (29%), and moderate or severe MR was noted in 25 patients (6%). One-year mortality rates were 4.8%, 12.4%, and 24%, respectively (p<0.001). Multivariate analysis revealed that mild MR was independently associated with increased 1-year mortality (p<0.05) after adjustment for age, gender, previous myocardial infarction, diabetes mellitus, systemic hypertension, Killip grade > or =2 on admission, and left ventricular ejection fraction < or =40%. The hazard ratio for 1-year mortality was 2.31 (95% confidence interval 1.03 to 5.20) for mild MR and 2.85 (95% confidence interval 0.95 to 8.51) for moderate or severe MR. Thus, mild MR detected by color Doppler echocardiography within the first 2 days of admission in patients with AMI is a significant independent risk predictor for 1-year all-cause mortality.

High-dose intravenous isosorbide-dinitrate is safer and better than Bi-PAP ventilation combined with conventional treatment for severe pulmonary edema

OBJECTIVE

To determine the feasibility, safety and efficacy of bilevel positive airway ventilation (BiPAP) in the treatment of severe pulmonary edema compared to high dose nitrate therapy.

BACKGROUND

Although noninvasive ventilation is increasingly used in the treatment of pulmonary edema, its efficacy has not been compared prospectively with newer treatment modalities.

METHODS

We enrolled 40 consecutive patients with severe pulmonary edema (oxygen saturation <90% on room air prior to treatment). All patients received oxygen at a rate of 10 liter/min, intravenous (IV) furosemide 80 mg and IV morphine 3 mg. Thereafter patients were randomly allocated to receive 1) repeated boluses of IV isosorbide-dinitrate (ISDN) 4 mg every 4 min (n = 20), and 2) BiPAP ventilation and standard dose nitrate therapy (n = 20). Treatment was administered until oxygen saturation increased above 96% or systolic blood pressure decreased to below 110 mm Hg or by more than 30%. Patients whose conditions deteriorated despite therapy were intubated and mechanically ventilated. All treatment was delivered by mobile intensive care units prior to hospital arrival.

RESULTS

Patients treated by BiPAP had significantly more adverse events. Two BiPAP treated patients died versus zero in the high dose ISDN group. Sixteen BiPAP treated patients (80%) required intubation and mechanical ventilation compared to four (20%) in the high dose ISDN group (p = 0.0004). Myocardial infarction (MI) occurred in 11 (55%) and 2 (10%) patients, respectively (p = 0.006). The combined primary end point (death, mechanical ventilation or MI) was observed in 17 (85%) versus 5 (25%) patients, respectively (p = 0.0003). After 1 h of treatment, oxygen saturation increased to 96 +/- 4% in the high dose ISDN group as compared to 89 +/- 7% in the BiPAP group (p = 0.017). Due to the significant deterioration observed in patients enrolled in the BiPAP arm, the study was prematurely terminated by the safety committee.

CONCLUSIONS

High dose ISDN is safer and better than BiPAP ventilation combined with conventional therapy in patients with severe pulmonary edema.

Feasibility of mitral flow assessment by echo-contrast ultrasound, part I: determination of the properties of echo-contrast agents

Data on the ultrasonic properties of commercially available contrast agents are limited by being instrument-dependent, especially with regard to their backscattering properties. The present work describes methods of measurements that provide instrument-independent estimations of a contrast agent's attenuation coefficient and integrated backscatter index and provide them as functions of its concentration. The two studied commercially available contrast agents were Albunex and Levovist SHU 508-A, both representative of agents in common use for echocardiography. The attenuation coefficients and integrated backscatter indices of both agents were found to be a linear function of their concentrations. Proportionality coefficients +/- their standard deviations are provided. Actually, square root values of the averaged backscatter indices normalized with respect to the rms of the reference signal were determined. The coefficients of proportionality were found to be: C(A) = 3.11+/-0.1813 dB/mm; C(L) = 0.07+/-0.005 dB/mm for attenuation coefficients of the Albunex and Levovist contrast agents, respectively, and the corresponding values for backscattering were: D(A) = 0.07+/-0.0054; D(L) = 0.02+/-0.0012. Being apparatus-independent, the findings of the study are important prerequisites for the use of these echo-contrast agents as an indicator in research for a quantitative assessment of blood flow.

The effect of aortic valve replacement on left ventricular mass assessed by echocardiography

AIMS

The aim of the study was to investigate whether aortic valve replacement (AVR) has different effects on the left ventricular mass (LVM) in patients with different types of aortic valve disease, i.e. aortic stenosis (AS), aortic regurgitation (AR), or combined disease.

METHODS AND RESULTS

We studied 100 patients with AS; (n=57), AR; (n=22), and combined disease; (n=21). Each patient was evaluated before and up to 8.7 years (mean follow-up period 1.42 +/- 1.65 years) after operation by transthoracic echocardiography. LVM was calculated based on echocardiographic parameters. Following AVR, the LVM for the entire group decreased from 373 +/- 145 g to 280 +/- 102 g (P=0.0001). The AS subgroup lost 13.7 +/- 30.7% from the preoperative LVM, compared to 28.8 +/- 24.8% in the AR subgroup (P<0.05) and 23.1 +/- 33.1% in the combined subgroup. The preoperative LVM was higher among patients with AR vs. AS patients (501 +/- 173 g vs. 319 +/- 100 g respectively, P<0.05). The decrease in LVM was significantly higher in patients with preoperative AR compared to AS patients (165 +/- 150 g vs. 58 +/- 96 g, respectively, P<0.05). However, the postoperative LVM remained higher among the former. The only preoperative parameter (of the LVM formula) that was different between AR and AS patients was the left ventricular end diastolic diameter (68 +/- 11 mm vs. 51 +/- 7 mm, respectively, P<0.05). No significant differences were found in wall thickness among the groups studied. Univariate analysis showed that gender (male), type of aortic valve disease (AR vs. AS), and larger prosthetic valve diameter correlated significantly with greater decrease in postoperative LVM. In multivariate analysis comparing the above variables between AS and AR subgroups, only the patient's gender (i.e. male) was identified as an independent predictor of LVM regression.

CONCLUSION

Patients with AR have a greater decline in LVM compared with patients with AS following AVR. The postoperative decline in LVM is higher among males and those with larger prosthetic valve diameter.

Feasibility of mitral flow assessment by echo-contrast ultrasound, part II: experimental study on a mechanical model of the left heart

The feasibility of assessing mitral flow by means of ultrasonic monitoring of backscattered power from an echo-contrast agent in the left atrium and left ventricle was studied. A mechanical model of the left heart was built in which two thin rubber balloons connected to each other in a feedback loop via two artificial heart valves mimicked the left atrium and left ventricle. The model was driven by compressed air. Its input and output flows were measured as the functions of a pacing rate, driving pressure and artificially introduced mitral regurgitation. These were compared with the corresponding data derived from the ultrasonic measurements that are based on the correlation between echo-contrast agent concentration in the volume of interest and the flow through it. Algorithms for quantitative estimations of forward stroke volume (cardiac output) and mitral regurgitation are given. This study shows, for the first time, both analytically and experimentally, that the pulsating modulation of contrast agent concentration vs. time curves in the ventricle and atrium volumes is closely related to the pulsating nature of the flow in the system. It also shows that the amplitude of the atrium concentration modulation is directly proportional to the maximum value of the incoming (to atrium) flow.

Minimal heparinization in coronary angioplasty--how much heparin is really warranted?

The purpose of the study was to assess the results of percutaneous transluminal coronary angioplasty (PTCA), performed with a single intravenous bolus of 2,500 U of heparin, in a nonemergency PTCA cohort. Three hundred of 341 consecutive patients (87.9%) undergoing PTCA were prospectively enrolled in the study. They received heparin, 2,500-U intravenous bolus, before PTCA, with intention of no additional heparin administration. Patient and lesion characteristics as well as PTCA results were evaluated independently by 2 physicians. Patients were followed up by structured telephone questionnaires at 1 and 6 months after PTCA. Mean activated clotting time obtained 5 minutes after heparin administration was 185+/-19 seconds (range 157 to 238). There were 3 (1%) in-hospital major adverse cardiovascular events: 2 deaths (0.66%), 1 (0.33%) Q-wave myocardial infarction. Emergency coronary surgery and stroke were not reported. Six patients (2%) experienced abrupt coronary occlusion within 14 days after PTCA, warranting repeat target vessel revascularization. Angiographic and clinical success were achieved in 96% and 93.3%, respectively. No bleeding or vascular complications were recorded. Six-month follow-up (184 patients) revealed 3 cardiac deaths (1 arrhythmic, 2 after cardiac surgery), 1 Q-wave myocardial infarction, and 9.7% repeat target vessel revascularization. This study suggests that very low doses of heparin and reduced activated clotting time target values are safe in non-emergency PTCA, and can reduce bleeding complications, hospital stay, and costs. Larger, randomized, double-blind heparin dose optimization studies need to confirm this notion.

L-NMMA (a nitric oxide synthase inhibitor) is effective in the treatment of cardiogenic shock

BACKGROUND

The objective was to assess the safety and efficacy of L-NMMA in the treatment of cardiogenic shock.

METHODS

We enrolled 11 consecutive patients with cardiogenic shock that persisted after >24 hours from admission, despite coronary catheterization and primary percutaneous transluminal coronary revascularization, when feasible, and treatment with mechanical ventilation, intraaortic balloon pump (IABP), and high doses of catecholamines. L-NMMA was administered as an IV bolus of 1 mg/kg and continuous drip of 1 mg. kg(-1). h(-1) for 5 hours. Treatment with catecholamines, mechanical ventilation, and IABP was kept constant throughout the study.

RESULTS

Within 10 minutes of L-NMMA administration, mean arterial blood pressure (MAP) increased from 76+/-9 to 109+/-22 mm Hg (+43%). Urine output increased within 5 hours from 63+/-25 to 156+/-63 cc/h (+148%). Cardiac index decreased during the steep increase in MAP from 2. 0+/-0.5 to 1.7+/-0.4 L/(min. m(2)) (-15%); however, it gradually increased to 1.85+/-0.4 L/(min. m(2)) after 5 hours. The heart rate and the wedge pressure remained stable. Twenty-four hours after L-NMMA discontinuation, MAP (+36%) and urine output (+189%) remained increased; however, cardiac index returned to pretreatment level. No adverse events were detected. Ten out of eleven patients could be weaned off mechanical ventilation and IABP. Eight patients were discharged from the coronary intensive care unit, and seven (64%) were alive at 1-month follow-up.

CONCLUSIONS

L-NMMA administration in patients with cardiogenic shock is safe and has favorable clinical and hemodynamic effects.

Aspergillus niger endocarditis in an immunocompetent patient: an unusual course

Aspergillus is an opportunistic nosocomial fungus generally associated with a high mortality rate. A niger has been rarely associated with infection, and most cases have occurred in patients who have recently undergone heart surgery or in immunocompromised patients. We present a case of an immunocompetent patient with A niger endocarditis which illustrates the difficulties in diagnosis and the possible insidious course of fungal endocarditis.

Spiral computerized tomography (dual helical mode) as a detector of aortic atheromas in patients with stroke and systemic emboli: additional benefit of the contrast-enhanced technique

BACKGROUND

Protruding aortic atheromas are a potential source of stroke and systemic emboli. The single modality currently available for their detection has been transesophageal echocardiography. However, TEE does not allow full visualization of the upper part of the ascending aorta and proximal aortic arch.

OBJECTIVES

To investigate whether double helical computerized tomography--both with and without contrast injection--may represent a useful technique for noninvasive detection of PAA in stroke patients.

METHODS

Forty consecutive patients > or = 50 years of age who sustained a recent ischemic stroke and/or systemic emboli (within 15 days after the onset of the event) were enrolled in the study and underwent TEE and DHCT without contrast injection using thin slice acquisition (3.2 mm thickness and 1.5 mm reconstruction increment). In addition, the last eight consecutive patients, after obtaining an unenhanced scan, underwent a contrast-enhanced DHCT following peripheral intravenous injection of a small amount of contrast material (15 ml of diatrizoate).

RESULTS

PAAs were demonstrated by TEE in 18 patients (45%); in 16 of them (89%) the atheromas were recognized by DHCT. Of the 22 patients without PAA on TEE, DHCT confirmed their absence in 18 (82%). DHCT yielded a sensitivity of 89%, a specificity of 82%, and an overall accuracy of 85%. The total number of protruding plaques detected by TEE was 43, of which 41 (95%) were correctly identified by DHCT. The mean thickness of the plaques was 5.6 +/- 2.4 mm on TEE, and 5.4 +/- 2.3 on DHCT (P = NS), with a good correlation between the modalities (r = 0.84). Contrast-enhanced DHCT scans demonstrated absolute equivalence to TEE in aortic areas defined as "clearly visualized by TEE." DHCT detected PAA between the distal ascending aorta and the proximal arch in seven patients; these atheromas were not included in the comparative analysis. In these "occult" areas, DHCT may be superior to TEE.

CONCLUSIONS

DHCT without contrast injection using thin slice acquisition may become a useful modality for rapid noninvasive detection of PAA. Contrast-enhanced DHCT scans significantly improve imaging quality and may be superior to TEE in the upper ascending aorta and the proximal arch (areas not well visualized by TEE).

Conversion of recent onset paroxysmal atrial fibrillation to normal sinus rhythm: the effect of no treatment and high-dose amiodarone. A randomized, placebo-controlled study

BACKGROUND

Spontaneous conversion of recent onset paroxysmal atrial fibrillation to normal sinus rhythm occurs commonly and is not affected by low-dose amiodarone treatment.

METHODS

In a randomized, placebo-controlled trial of 100 patients with paroxysmal atrial fibrillation of recent onset (<48 h) we compared the effects of treatment with continuous intravenous amiodarone 125 mg per hour (total 3 g) and intravenous placebo. Patients in the placebo group who did not convert to normal sinus rhythm within 24 h were started on amiodarone therapy.

RESULTS

Conversion to normal sinus rhythm occurred within 24 h in 32 of 50 patients (64%) in the placebo group, most of whom converted within 8 h. Lower conversion rates were observed in patients with hypertension, ischaemic heart disease or congestive heart failure and in patients with echocardiographic findings of left atrial diameter above 45 mm, ejection fraction below 45% or significant mitral regurgitation. However, in most patients these clinical or echocardiographic risk factors of decreases in conversion rate were not present. In such patients the spontaneous conversion rate was approximately 90%. The conversion rate during 24 h of treatment in the amiodarone group was 92% (P=0.0017, compared to the placebo group). In this group, the conversion rate was largely unaffected by baseline characteristics. Of the 18 patients who did not convert with placebo, 15 (85%) converted after being crossed over to amiodarone. All patients not responding to high-dose amiodarone were in chronic atrial fibrillation within 1 month. In patients still in atrial fibrillation after 8 h of treatment, the pulse rate decreased significantly more in the amiodarone as compared to the placebo group (83+/-15 vs 114+/-20 beats. min(-1), P=0.0014).

CONCLUSION

The spontaneous conversion of recent onset paroxysmal atrial fibrillation is high and approaches 90% in specific clinical and echocardiographically defined subgroups. Intravenous high-dose amiodarone safely facilitates conversion of paroxysmal atrial fibrillation. However, such treatment should be reserved for patients with unfavourable risk factor profiles, not converting during 8 h of observation or requiring rate control.

Allicin-induced decrease in formation of fatty streaks (atherosclerosis) in mice fed a cholesterol-rich diet

BACKGROUND

Garlic (Allium sativum) has been considered to exhibit therapeutic features for many years. The effects of garlic on levels of serum lipids and on atherosclerosis have been investigated extensively. We have previously demonstrated that allicin, an active component of garlic, exerts a beneficial effect on lipid profile in hyperlipidemic rabbits.

OBJECTIVE

To investigate the effects of allicin on formation of fatty streaks (atherosclerosis) and lipid profile in mice.

METHODS

Allicin was extracted from garlic and kept in a buffer citrate solution at 4 degrees C. Sixty C57BL/6 mice were fed Paigen diet (17% fat, 1.25% cholesterol) for 15 weeks. Thirty randomly selected animals were administered allicin solution (9 mg/kg) and 30 were administered placebo. Blood lipid profile was evaluated five times during the study. At the end of the 15-week period, the animals were killed and the aortic sinus was evaluated for formation of fatty streaks (atherosclerosis).

RESULTS

We observed no statistically significant differences between blood lipid profiles of groups. Microscopic evaluation of aortic sinus formation of fatty streaks (atherosclerosis), however, showed that values for mice in the allicin-treated group were significantly lower: areas of formation of fatty streaks (atherosclerosis) were 13,440 +/- 3310 and 23,410 +/- 3723 micron 2, respectively, for allicin-treated and control mice (means +/- SEM; P = 0.023).

CONCLUSIONS

These results indicate that allicin reduces formation of fatty streaks (atherosclerosis) in hyperlipidemic mice. These changes do not seem to occur through an alteration in blood lipid profile.

Usefulness of losartan, captopril, and furosemide in preventing nitrate tolerance and improving control of unstable angina pectoris

Sixty consecutive normotensive patients with unstable angina pectoris, who were on continuous intravenous isosorbide dinitrate (ISDN) treatment and had not previously received angiotensin II receptor antagonists, angiotensin-converting enzyme (ACE) inhibitors, or diuretics were randomly assigned to treatment groups receiving intravenous ISDN for 72 hours. No additional treatment was given to group A (n = 15). Captopril, in a test dose of 6.25 mg, and followed by 12.5 mg 3 times daily for 24 hours and 25 mg 3 times daily for the next 24 hours, was given to group B (n = 15). The same dose of captopril plus 40 mg of furosemide in the morning were given to group C (n = 15). Losartan, in a single dose of 25 mg/day and increased to 50 mg after 24 hours was given to group D (n = 15). Nitrate tolerance was evaluated at 24-hour intervals at trough levels of each of the drugs by administering intravenous ISDN (1 mg bolus dose every 4 minutes) and recording the total ISDN test dose required to decrease the mean arterial blood pressure by > or =10%. Treatment with continuous ISDN only (group A) induced nitrate tolerance. The ISDN (mean +/- SD) test dose was 3.5 +/- 1.8 mg at baseline, increasing to 4.9 +/- 2.4 mg at 24 hours, and 8.0 +/- 3.0 mg at 48 hours. The addition of increasing doses of captopril to the continuous ISDN treatment (group B) completely prevented nitrate tolerance. Losartan, however, did not attenuate nitrate tolerance at 24 hours and attenuated it only partially at 48 hours. The addition of furosemide to captopril had no further effect on nitrate tolerance. Of 15 patients in group A (ISDN only), 4 (27%) experienced recurrent ischemic events requiring urgent coronary catheterization. No such events were recorded in group B (captopril), but did occur in 1 patient in each of group C (captopril plus furosemide) and D (losartan) (p = 0.083). Thus, the addition of captopril to the ISDN treatment regimen prevented tolerance to nitrates and improved angina control with apparent safety. Losartan also decreased nitrate tolerance, although to a lesser extent, and also improved angina control. The addition of furosemide to captopril conferred no further benefit.

Dual-helical CT for detecting aortic atheromas as a source of stroke: comparison with transesophageal echocardiography

PURPOSE

To investigate whether unenhanced dual-helical computed tomography (CT) is useful in the rapid, noninvasive detection of protruding aortic atheromas.

MATERIALS AND METHODS

Thirty-two consecutive patients at least 50 years of age who had recent ischemic stroke, systemic emboli, or both, underwent transesophageal echocardiography (TEE) and unenhanced dual-helical CT with thin sections (section thickness, 3.2 mm; reconstruction increment, 1.5 mm).

RESULTS

TEE demonstrated protruding aortic atheromas 15 patients (47%); dual-helical CT depicted protruding aortic atheromas in 13 of those 15 patients (87%). Of the 17 patients without a protruding aortic atheroma at TEE, dual-helical CT helped confirm the absence in 14 (82%). Dual-helical CT yielded a sensitivity of 87%, a specificity of 82%, and an overall accuracy of 84%. Thirty-six protruding plaques were detected with TEE, of which 34 (94%) were correctly identified with dual-helical CT. Of those 34 plaques, 27 (79%) contained variable amounts of calcium and seven (21%) showed hypoattenuation suggestive of soft plaques and thrombi. In six patients, dual-helical CT depicted a protruding aortic atheroma between the distal ascending aorta and the proximal arch; these plaques were not included in the comparative statistics and were analyzed separately.

CONCLUSION

Unenhanced dual-helical CT with thin sections appears to be useful for the rapid, noninvasive detection of a protruding aortic atheroma, especially in areas not clearly visualized with TEE.

Automatic assessment of cardiac function from short-axis MRI: procedure and clinical evaluation

Cardiac magnetic resonance imaging (MRI) provides a wealth of morphological and physiological information. Automatic extraction of this information is possible by implementing various image processing techniques. However, existing procedures mostly rely on extensive human interaction and are seldom evaluated on a clinical scale. In this study, a nearly automatic process that extracts physiological parameters from cardiac MR images has been both developed and clinically evaluated. Raw images were obtained in the short-axis view and acquired by a gradient-cho (GE) protocol. In images selected to be analyzed, the only manual step required is the indication of a point in the center of the left ventricle (LV). From a set of such images, the process extracts endocardial and epicardial contours and calculates left ventricular volumes, mass and ejection fraction (EF). The process implements novel approaches to image processing techniques such as thresholding and shape extraction and can be adapted to other acquisition protocols. The process has demonstrated a clear potential for accurate extraction of the endocardial contour but a lower one with respect to the epicardial contour as a result of the low contrast between myocardium and some surrounding tissues, generated by the gradient-echo protocol. The ability of the process to asses physiological parameters has been subjected to a systematic clinical evaluation, which compared parameters, derived manually and automatically, in 10 healthy subjects and 10 patients. The evaluation has indicated that although individual volumes and mass were not accurately assessed, the automatic process has shown high potential for assessing the ejection fraction with relatively high accuracy and reliability.

Disrupted mobile aortic plaques are a major risk factor for systemic embolism in the elderly

Protruding aortic plaques--especially those with mobile properties--on transesophageal echocardiography (TEE) are a potential source of stroke and systemic embolism in the elderly. Whether the various morphologies of atheromas with mobile components represent potential differences in the risk for embolic events has not been thoroughly elucidated. The goal of the present study was to determine the association between embolic events and the various types of mobile lesions in the thoracic aorta. Our population consisted of 569 consecutive patients (age 18-83 years) referred for TEE over 27 months; 108 (19%) of them were referred to evaluate recent embolism (cerebral in 97 and peripheral or both in 11; group I) and the remaining 461 were admitted for reasons unrelated to embolism (group II). In group I, 35 patients (32%) exhibited protruding plaques; those were fixed in 10 (9%) and with a mobile component in 25 (23%). In group II, plaques were found in only 13 patients (3%); fixed in 9 (2%) and mobile in 4 (1 %). Twenty-four patients with mobile lesions in group I were > 50 years old, and 21 of them (88%) were > 60 years old. While the presence of fixed plaques was associated with a moderate increase in the risk for systemic embolism (adjusted odds ratio 4.1; 95% confidence interval 1.3-56.4), mobile lesions were linked to a striking augmentation of this risk (odds ratio 30.1; 95% confidence interval 7.8-132.6). The majority of mobile lesions (76%) in group I represented disrupted atheromas with characteristic ulcerations or echolucency within the plaque suggestive of intraatheroma hemorrhage, whereas these TEE features were not observed in 89% of the mobile lesions in group II (p = 0.0003). We conclude that among the various types of mobile aortic lesions, the disrupted protruding plaques are a major risk factor for stroke and embolic events in the elderly.

Echocardiographic left ventricular remodeling and pseudohypertrophy as markers of hypovolemia. An experimental study on bleeding and volume repletion

BACKGROUND

Monitoring intravascular volume during surgery, especially in major cardiovascular procedures is necessary for appropriate fluid restoration and the maintenance of an adequate cardiac output. In estimating preload, both standard hemodynamic and echocardiographic parameters have been limited. The purpose of this study was to further define the effects of induced hypovolemia on the echocardiographic parameters. In particular, we sought to show whether a decrease in echocardiographic left ventricular area and volume was associated with a significant increase in left ventricular wall thickness (left ventricular pseudohypertrophy) and with changes in LV function. In addition, we sought to investigate the effects of rapid restoration of blood volume on cardiac dimensions and function.

METHODS AND RESULTS

Seven anesthetized pigs underwent systemic and right heart pressures and cardiac output measurements. Two-dimensional echocardiographic parasternal long- and short-axis views were obtained during graded bleeding by rapid withdrawal of blood from an arterial cannula, with increments of 5% each up to 30% of calculated blood volume. After completion of the bleeding, the entire amount of the blood withdrawn was retransfused within 4 to 5 minutes. Both hemodynamic and echocardiographic measurements were performed at baseline, immediately after the completion of each stage of bleeding and after blood restoration. Mean (+/- standard deviation) left ventricular wall thickness (mean of septal and posterior wall thickness) was 6.3 +/- 0.1 mm at baseline, 8.3 +/- 1.5 mm at peak bleeding, and 6.2 +/- 0.1 after restoration (p < 0.01). Left ventricular mass did not change during the experiment. Left ventricular end-diastolic volume was 62.8 +/- 20.3 ml at baseline, 37.5 +/- 12.4 ml at peak bleeding (p < 0.0001), and 65.9 +/- 16.7 ml after blood restoration (p < 0.001 compared with 30% bleeding). H/r ratio (posterior wall thickness divided by left ventricular radius) increased from 0.29 +/- 0.07 at baseline to 0.50 +/- 0.19 at peak bleeding returning to 0.26 +/- 0.04 after restoration. Left ventricular ejection fraction was 0.53 +/- 0.10 at baseline and 0.55 +/- 0.20 at peak bleeding (not significant), decreasing to 0.38 +/- 0.11 after blood restoration (p < 0.05 compared with 30% bleeding). End-diastolic volume correlated closely with right atrial pressure (r = -0.82), capillary wedge pressure (r = -0.78), and stroke volume (r = 0.74). Left ventricular ejection fraction inversely correlated with left ventricular end-diastolic volume (r = -0.48) and with end-systolic wall stress (r = -0.62). The changes in interventricular septal and posterior wall thickness were inversely related to left ventricular end-diastolic volume (r = -0.72 and -0.35, respectively).

CONCLUSIONS

This study shows that transient concentric left ventricular remodeling (pseudohypertrophy), a phenomenon previously described in cardiac tamponade and during rapid atrial pacing is commonly seen during hypovolemia. This new sign may further enhance the echocardiographic estimation of left ventricular preload.

Stress echocardiography beyond coronary artery disease

Doppler echocardiography has become the major diagnostic tool of evaluation of valvular heart disease and the cardiomyopathies because of its ability to provide valuable haemodynamic information accurately and non-invasively. It is therefore ideally suited for haemodynamic stress testing in these patients. In aortic stenosis, dobutamine echocardiography can distinguish severe from non-severe stenosis in patients with depressed left ventricular function, low transvalvular gradients, and a relatively small (flow-related) valve area at baseline. Patients with non-severe aortic stenosis increase cardiac output and valve area with dobutamine infusion while the transvalvular gradient does not change significantly. In severe aortic stenosis, the pressure gradient increases significantly with stroke volume, but valve area does not. In patients who fail to increase stroke volume (absent contractile reserve) and therefore do not show a change in haemodynamics, the severity of the lesion is 'indeterminate'; these patients are characterized by a very poor prognosis. In mitral stenosis, patients can be identified who increase valve area during exercise, which is the fundamental mechanism by which stroke volume can be increased in mitral stenosis. The increase in pulmonary artery pressure during exercise (assessed from tricuspid regurgitant signal) can be dramatically different in patients with comparable resting haemodynamics; therefore exercise echocardiography provides information which cannot be obtained from resting measurements alone and can help to guide medical and surgical therapy. Whether stress echocardiography may be similarly helpful in patients with regurgitant lesions is still a subject of investigation. Exercise Doppler echocardiographic studies following aortic valve replacement (small valves) can identify impairment of systolic and diastolic function indicative of 'valve prosthesis-patient mismatch'. In hypertrophic cardiomyopathy the dynamics of outflow obstruction can be assessed following exercise or pharmacological intervention. In dilative cardiomyopathy, contractile reserve can be assessed by dobutamine echocardiography which may help in evaluating prognosis, guiding heart failure therapy, and monitoring therapy with cardiotoxic chemotherapeutic agents.

Echocardiographic imaging of a basket catheter for mapping and ablation of ventricular tachycardia in pigs

Our objective was to assess the feasibility and efficacy of the recently described left ventricular simultaneous deployment of a new multi-electrode mapping catheter and a standard radio-frequency ablation catheter in pigs, with echocardiography monitoring and fluoroscopy guidance. Introduction and deployment of both catheters in five healthy anesthetized pigs were guided on-line by fluoroscopy and monitored with transthoracic echocardiography. Heart rate and femoral blood pressure were also continuously monitored. Both catheters were deployed for up to 5 hours. Three animals underwent three to five radio-frequency energy applications. Left ventricular dimensions obtained from long axis two-dimensional echocardiography imaging before and after basket-catheter deployment in the left ventricular cavity, were 3.9 +/- 0.3 versus 3.7 +/- 0.6 cm at end-diastole and 2.8 +/- 1.1 versus 2.6 +/- 0.8 cm at end-systole, respectively (mean +/- standard error of the mean, p > 0.05). Shortening fraction measured from long axis two-dimensional echocardiography images before and after catheter deployment was 28% +/- 10% versus 25% +/- 5%, respectively (mean +/- standard error of the mean, p > 0.05). Additional findings included the following: (1) good conformation of the multi-electrode mapping catheter to the left ventricular dimensions during diastole; (2) absence of catheter-induced aortic and/or mitral insufficiency, as well as left ventricular outflow tract obstruction; (3) absence of damage to mitral and aortic valves or to the left ventricular wall. Postmortem examination and hemodynamic measurements confirmed these findings and showed only minor subendocardial hemorrhages; (4) radio-frequency energy application produced intracavitary bubbles, which were demonstrable echocardiographically, enabling identification of the gross anatomic location of ablation sites. Echocardiography during simultaneous deployment of multi-electrode mapping catheter and radio-frequency ablation catheters enables estimation of mechanical interaction with the left ventricle and detects interaction with myocardial/valvular function. During radio-frequency energy application, bubble production may identify gross anatomic location of ablation.

Percutaneous multielectrode endocardial mapping during ventricular tachycardia in the swine model

BACKGROUND

Identification of critical areas within the ventricular tachycardia circuit is a prerequisite for catheter ablation. Currently, mapping during ventricular tachycardia, usually performed with standard catheters, is difficult and time-consuming and can be used only in patients with hemodynamically stable tachycardia.

METHODS AND RESULTS

A total of 43 pigs underwent closed-chest induction of myocardial infarction. A basket-shaped catheter carrying 64 electrodes was deployed in the left ventricle during normal sinus rhythm. Unipolar pacing at 3 mA was successful in 78% of the basket catheter electrodes, demonstrating good electrode-tissue contact. Hemodynamic and echocardiographic measurements did not reveal any significant interference with myocardial or valvular function during or after catheter deployment. One hundred eighteen episodes of monomorphic ventricular tachycardia were induced in 28 pigs through right ventricular stimulation, 81 of which were mapped and analyzed. Ventricular tachycardia mapping was rapid, requiring only several beats and < 10 seconds to complete. Presystolic potentials, a possible target for ablation, were identified in 58% of the tachycardia episodes mapped. Pathological examination revealed only minor valvular and endocardial catheter-induced lesions immediately after mapping and none a month later.

CONCLUSIONS

The multielectrode catheter enables rapid and safe percutaneous endocardial mapping of ventricular tachycardia in the swine model. Exploration of the clinical potential of the multielectrode catheter seems warranted.

Shortened Doppler-derived mitral A wave deceleration time: an important predictor of elevated left ventricular filling pressure

OBJECTIVES

The aim of this study was to investigate whether a new variable of mitral inflow, A wave deceleration time, identifies patients with elevated left ventricular filling pressures.

BACKGROUND

In patients with an elevated left ventricular end-diastolic pressure, the increase in left ventricular pressure after atrial contraction rapidly exceeds left atrial pressure, resulting in abrupt cessation of the A wave. Therefore, we postulated that a shortening of A wave deceleration time might be a marker for elevated end-diastolic pressure.

METHODS

Adequate pulsed Doppler mitral inflow velocities could be recorded in 40 of 44 consecutive patients undergoing cardiac catheterization with capillary wedge pressure in 20 patients, and within 1 h after left ventricular end-diastolic pressure recording in 20. Fifteen healthy volunteers were also studied.

RESULTS

Left ventricular end-diastolic pressure was 8 to 35 mm Hg, and mean pulmonary wedge pressure was 6 to 37 mm Hg. Close correlations were found between A wave deceleration time and mean pulmonary wedge pressure (r = -0.87) and left ventricular end-diastolic pressure (r = -0.74). There were modest correlations between both pressures and peak E/A, E wave deceleration time and A wave duration, respectively; r = 0.59, -0.30 and -0.58 for capillary wedge and r = 0.25, -0.38 and -0.49 for end-diastolic pressures. A wave deceleration time </= 60 ms predicted left ventricular end-diastolic and mean pulmonary wedge pressures > 18 mm Hg, respectively, with a sensitivity of 67% and 89% and specificity of 100% for both.

CONCLUSIONS

A shortened Doppler mitral inflow A wave deceleration time is a useful index of elevated left ventricular filling pressure.

Alteration of lipid profile in hyperlipidemic rabbits by allicin, an active constituent of garlic

BACKGROUND

The effect of garlic on the serum lipid profile has been the subject of controversy. This study was therefore designed to examine the effects of allicin, an active constituent of garlic, on the lipid profile in a rabbit model.

METHODS

Allicin was produced by reacting alliin, synthesized in our laboratory, with purified alliinase. Nineteen New Zealand White rabbits were fed a cholesterol-rich diet (0.25% cholesterol) for 18 weeks. Ten rabbits received freshly produced allicin (3 mg/kg orally) starting at 8 weeks, and nine received placebo. There was no significant difference between the lipid profiles of the two groups at baseline up to 8 weeks.

RESULTS

From day 28 of allicin supplementation a significant difference was found between the allicin and placebo groups in the graph regression lines describing the influence of allicin on serum cholesterol: Y = 41.39 + 8.69 multiplied by day (control) versus Y = -877.24 + 17.67 multiplied by day (allicin). The same trend was found for low-density lipoprotein concentrations: Y = 10.3 + 8.4 multiplied by (control) versus Y = -750.4 + 15.7 multiplied by day (allicin). The serum high-density lipoprotein levels also differed significantly between the groups: Y = 20.29 + 0.24 multiplied by day (control) versus Y = -109.9 + 1.65 multiplied by day (allicin).

CONCLUSIONS

Our results indicate that allicin has a beneficial effect on the serum lipid profile in hyperlipidemic rabbits, and should be further tested clinically.

Exogenous insulin-like growth factor II enhances post-infarction regional myocardial function in swine

OBJECTIVES

Insulin-like growth factor II (IGF-II) promotes cardiac myocyte growth and contractility in vitro. This study was designed to investigate the effect of exogenous IGF-II on regional myocardial function at the area of infarct in the pig.

METHODS

Myocardial infarction was induced in 12 female anaesthetized pigs by affigel blue beads, embolizing microvessels of the left anterior descending coronary artery distribution. In the experimental group (n = 6), IGF-II (0.12 microgram.kg-1 in two animals and 0.6 microgram.kg-1 in four) was incorporated into the beads and delivered by them to the infarct area. Myocardial function was followed echocardiographically, and the excised heart was analysed immunohistochemically and histopathologically.

RESULTS

Myocardial function in injured zones, inversely related to an echocardiographic segmental wall motion score (mean +/- SEM), was similar between the two groups at baseline, but at 4 weeks post-infarction was significantly (P = 0.008) reduced in the control group (0.58 +/- 0.38 vs 3.42 +/- 0.84), in contrast to nearly baseline values in the experimental group (0.58 +/- 0.33 vs 1.17 +/- 0.42, P = 0.41). Cardiac performance in injured segments was significantly better after myocardial injury in the experimental group (P = 0.04). Tissue samples from both groups (4 weeks post-infarction), stained with haematoxylin and eosin demonstrated peri-infarct myocyte hypertrophy, corresponding to regions selectively stained by an antibody for CD56, which highlights growing cardiac myocytes. By image analysis semi-quantification, staining for CD56 was significantly (P = 0.04) higher in the peri-infarct region of the experimental group, as compared with controls (106.5 +/- 2.8 vs 92 +/- 4.4 gray level units). Microvessels stained for von-Willebrand factor were similar in number in both groups (P = 0.8), as were mesenchymal cells stained for vimentin (P = 0.7).

CONCLUSIONS

Exogenous IGF-II, delivered to the infarct area ameliorates regional cardiac function in the pig, perhaps by inducing peri-infarct myocyte growth.