Continuous imaging of regional myocardial blood flow in dogs using krypton-81m

The unique physical properties of the freely diffusible gas krypton-81 m allowed continuous imaging of regional myocardial blood flow in dogs when infused into the aortic root. Regional changes in myocardial perfusion related to transient coronary artery occlusion were demonstrated both as high resolution gamma camera images and as a quantitative strip chart record.     

Mechanisms underlying spontaneous and induced ventricular arrhythmias in patients with idiopathic dilated cardiomyopathy

BACKGROUND: To define the electrophysiological mechanism(s) of inducible and spontaneously occurring ventricular arrhythmias associated with nonischemic cardiomyopathy, 3-dimensional intraoperative mapping from 156 intramural sites was performed in 6 patients with idiopathic dilated cardiomyopathy undergoing cardiac transplantation. METHODS AND RESULTS: Electrode density was sufficient to determine the mechanism for 52 of 74 beats of nonsustained ventricular tachycardia (VT) induced by programmed stimulation and 9 of 11 beats of spontaneous ventricular arrhythmias. The first, second, and third extrastimuli (S2 through S4) conducted with progressively greater degrees of conduction delay (total activation times [TAs] of 144+/-5, 166+/-5, and 194+/-5 ms, respectively) owing to slow conduction and on occasion intramural block. The first beats of induced VT arose from subendocardial or subepicardial sites distant from areas of marked conduction delay by a focal mechanism on the basis of the absence of intervening electrical activity between the termination of the last extrastimulus and the initiation of VT (123+/-31 ms). Subsequent beats arose by a focal mechanism and conducted with a TA of 127+/-6 ms (P=NS versus initiating beats of VT [118+/-9 ms]). Spontaneous ventricular arrhythmias initiated in the subendocardium by a focal mechanism and conducted with a TA of 138+/-5 ms. Tissue analysis demonstrated a variable degree of interstitial fibrosis at sites of focal activation. Sites of conduction delay or block typically exhibited marked interstitial and/or replacement fibrosis but were spatially distant from sites initiating VT. CONCLUSIONS: Spontaneous and induced ventricular arrhythmias in patients with end-stage idiopathic cardiomyopathy can arise in the subendocardium or subepicardium by a focal mechanism.     

Right and left ventricular geometry and myocyte contractile processes with dilated cardiomyopathy: myocyte growth and beta-adrenergic responsiveness

OBJECTIVES: Comparison of the effects of supraventricular tachycardia-induced dilated cardiomyopathy on left and right ventricular isolated myocyte geometry and function. BACKGROUND: Chronic ventricular tachycardia and supraventricular tachycardia cause left ventricular dilation and dysfunction in humans. However, it is unknown whether supraventricular tachycardia-induced dilated cardiomyopathy is a homogenous process for both the left and right ventricles. METHODS: Dilated cardiomyopathy was induced by rapid atrial pacing (240 beats/min, 3 weeks) in 5 pigs. Five age- and weight-matched pigs served as controls. Ventricular mass was measured, myocyte dimensions were obtained, and isolated right and left ventricular myocyte contractile performance was evaluated at baseline and after beta-adrenergic receptor stimulation. RESULTS: With the development of dilated cardiomyopathy, there was no change in left ventricular mass. In contrast, right ventricular mass was increased, as was right ventricular myocyte cross-sectional area. In the control group, baseline right ventricular myocyte contractile function was increased compared to left ventricular myocytes. beta-adrenergic receptor stimulation increased myocyte contractile function in both left and right ventricular myocytes. With supraventricular tachycardia-induced cardiomyopathy, both left and right ventricular myocyte contractile function and beta-adrenergic responsiveness were reduced. CONCLUSIONS: This study demonstrated differences in left and right ventricular myocyte growth with supraventricular tachycardia-induced dilated cardiomyopathy and this differential growth response was associated with changes in contractile performance. Thus, in this model of cardiomyopathic disease, left and right ventricular growth and changes in contractile performance are not a homogenous process.     

Combined assessment of myocardial perfusion and left ventricular function with exercise technetium-99m sestamibi gated single-photon emission computed tomography can differentiate between ischemic and nonischemic dilated cardiomyopathy

The purpose of this study was to determine whether exercise technetium-99m sestamibi gated single-photon emission computed tomography (SPECT) accurately distinguishes between patients with ischemic cardiomyopathy and patients with nonischemic left ventricular systolic dysfunction. Noninvasive tests have previously failed to accurately separate patients with ischemic cardiomyopathy from those with nonischemic cardiomyopathy. Technetium-99m gated SPECT imaging offers advantages that have the potential to overcome the limitations of previous studies. Thirty-seven adults with a left ventricular ejection fraction < or = 35%, including 24 patients with nonischemic cardiomyopathy and 13 patients with ischemic cardiomyopathy, were prospectively evaluated using symptom-limited metabolic exercise treadmill testing with technetium-99m sestamibi gated SPECT imaging. Interpretation of myocardial perfusion and regional wall motion was performed, using a 17-segment model. Summed stress, rest, and reversibility perfusion defect scores were determined, and the variance of segmental wall motion scores was computed. Summed stress, rest, and reversibility perfusion defect scores were significantly lower in nonischemic cardiomyopathy patients, compared with those with ischemic cardiomyopathy (summed stress defect score: 6.9 +/- 3.8 vs 32.9 +/- 7.7, respectively, p <0.001). Variability in segmental wall motion was also significantly lower in patients with nonischemic cardiomyopathy compared with those with ischemic cardiomyopathy (variance: 0.3 +/- 0.3 vs 1.2 +/- 0.8, respectively, p <0.001). Thus, assessment of myocardial perfusion and regional ventricular function with exercise technetium-99m sestamibi gated SPECT imaging can reliably distinguish between patients with ischemic cardiomyopathy and patients with nonischemic dilated cardiomyopathy.     

Evaluation of myocardial perfusion and ventricular shape in hypertrophic cardiomyopathy using 99mTc-tetrofosmin scintigraphy: comparison with 201Tl myocardial scintigraphy

Hypertrophic cardiomyopathy (HCM) is known to have the impairment of myocardial perfusion as well as irregularly hypertrophic myocardium. To evaluate myocardial perfusion and ventricular shape in HCM, 99mTc-Tetrofosmin scintigraphy was performed after exercise (Ex) and at resting state (Re) in 10 patients with HCM and was compared with early image (Ea) and delayed image (De) of 201Tl scintigraphy performed after exercise. SPECT images of both 99mTc-Tetrofosmin and 201Tl scintigraphy were analyzed with five scaled visual scores set in 18 segments. The complete concordance ratio between 99mTc-Tetrofosmin (Ex and Re) and 201Tl (Ea and De) images in segmental analysis was 75%. Image quality of 99mTc-Tetrofosmin was seemed to be superior to that of 201Tl scintigraphy. In 9 patients with HCM, 99mTc-Tetrofosmin scintigraphy was performed under the ECG gating and the thickness of septal and free wall was measured. Good correlation was observed with the data by ultrasound cardiography (r = 0.79, p < 0.002 in wall thickness, r = 0.84, p < 0.01 in the ratio of septal wall thickness to free wall thickness). Left ventricular shape (ventricular long axis) was closely resemble to that of left ventriculography by contrast medium. In conclusion, 99mTc-Tetrofosmin scintigraphy is useful for the evaluation of myocardial morphology as well as perfusion abnormality.     

Ultrastructural changes of blood capillaries in patients with microvascular angina, hypertrophic cardiomyopathy, and dilated cardiomyopathy

The rat model has been used to present evidence of the effect of surgical damage on the immune system. Syngeneic small bowel transplantation (SBT) has been used to show an increased incidence of graft-versus-host disease (GVHD) as well as thymic atrophy and altered host T cell proliferative response. Syngeneic auxiliary SBT was carried out between (LEW x BN)F1 hybrids. Varying amounts of LEW mesenteric lymphocytes were injected into the last animals to induce GVHD. Results showed that in the SBT recipients the incidence of lethal GVHD was increased when compared with untreated or sham-laparotomy controls. Marked thymic atrophy was also observed, while the number of hepatic lymphocytes increased transiently. Lymphocyte proliferation in response to concanavalin A or interleukin-2 was impaired for up to 21 days postoperatively, whereas the mixed lymphocyte reaction reactivity was not affected. These results show that the number and proliferative activity of thymic T cells were impaired after major small bowel transplantation surgery and that extrathymic lymphocytes were developed in the liver.     

Effects of partial left ventriculectomy on left ventricular performance in patients with nonischemic dilated cardiomyopathy

OBJECTIVES: This study sought to assess the effects of partial left ventriculectomy (PLV) on left ventricular (LV) performance in a series of consecutive patients with nonischemic dilated cardiomyopathy. BACKGROUND: Reduction of LV systolic function in patients with heart failure is associated with an increase of LV volume and alteration of its shape. Recently, PLV, a novel surgical procedure, was proposed as a treatment option to alter this process in patients with dilated cardiomyopathy. METHODS: We studied 19 patients with severely symptomatic nonischemic dilated cardiomyopathy, before and 13+/-3 days after surgery, and 12 controls. Single-plane left ventriculography with simultaneous measurements of femoral artery pressure was performed during right heart pacing. RESULTS: The LV end-diastolic and end-systolic volume indexes decreased after PLV (from 169 to 102 ml/m2, and from 127 to 60 ml/m2, respectively, p < 0.0001 for both). Despite a decrease in LV mass index (from 162 to 137 g/m2, p < 0.0001), there was a significant decrease in LV circumferential end-systolic and end-diastolic stresses (from 277 to 159 g/cm2, p < 0.0001 and from 79 to 39 g/cm2, p = 0.0014, respectively). Ejection fraction improved (from 24% to 41%, p < 0.0001); the stroke work index remained unchanged. CONCLUSIONS: The PLV improves LV performance by a dramatic reduction of ventricular end-systolic and end-diastolic stresses. Further studies are needed to assess whether this effect is sustained during long-term follow-up and to define the role of PLV in the treatment of patients with dilated cardiomyopathy.     

Assessment of right ventricular function and interstitial fibrosis in idiopathic dilated cardiomyopathy: hemodynamic correlates and prognostic value

BACKGROUND: Right ventricular (RV) function and morphometric quantitation of interstitial fibrosis in idiopathic dilated cardiomyopathy (IDC) have not been the subject of specifically designed clinical observations. In particular, their role in routine assessment and prognostic evaluation of patients (pts) with IDC remains to be settled. METHODS: Eighty-one consecutive IDC patients (63 M, 18 F; mean age 52 +/- 11 yrs) with left ventricular (LV) systolic dysfunction (angiographic ejection fraction - EF - < 55%), normal coronary arteries and no histologic evidence of myocarditis were studied. Cardiac catheterization and endomyocardial biopsy (EMB) were routinely performed in all cases. RV volumes and EF were obtained by angiography according to Ferlinz' method and interstitial fibrosis was quantitated by computer-assisted morphometric analysis. These data were analyzed in order to study correlations with hemodynamic parameters and to assess their prognostic value in a long-term follow-up. RESULTS: In the study population, right ventricular EF was significantly lower than in normal controls (35 +/- 11% vs 53 +/- 6%, p < 0.0001) and showed a significant positive correlation with LV EF (r = 0.54; p < 0.0001), and a weak but significant negative correlation with fibrosis (r = -0.29; p = 0.03). RV volumes, but not EF, were significantly related to mean pulmonary pressure. At multivariate analysis, RV end-diastolic volume (EDV) and EF were the two independent predictors of severe heart failure (NYHA class III-IV). After a mean follow-up of 64 +/- 36 months, 20 pts died and 9 had heart transplantation, for a 63% transplant-free survival rate (TFS). Multivariate analysis identified three independent predictors of TFS: LV stroke work index (p < 0.0001), RV stroke work index (p = 0.02) and RV EDV (p = 0.03). Fibrosis was predictive of survival only in the subgroup with LV EF < 20%. CONCLUSIONS: Assessment of RV function provides useful information in the evaluation of hemodynamic profile and prognosis of pts with IDC. Quantitation of interstitial fibrosis by morphometry provides little additional data.     

Coronary vasodilatory capacity is impaired in patients with dilated cardiomyopathy

Increases in wall stress because of left ventricular enlargement and/or alterations in coronary vasomotor tone might affect myocardial blood flow and vasodilatory capacity in patients with dilated cardiomyopathy. To test this hypothesis myocardial blood flow was measured at rest and during intravenous administration of dipyridamole (0.56 mg/kg) using dynamic nitrogen 13-ammonia positron emission tomography (two-compartment model) in 10 patients with dilated cardiomyopathy (mean left ventricular ejection fraction 28 +/- 8% 1 woman, 9 men; 47 +/- 13 years of age). Ten age and gender matched healthy volunteers served as controls. Coronary artery disease was ruled out by coronary angiography and left ventricular hypertrophy by two dimensional-echocardiography. Baseline heart rate (70 +/- 13 v 64 +/- 12 bpm), systolic blood pressure (111 +/- 20 v 114 +/- 12 mm Hg) and rate pressure product (7,686 +/- 1264 v 7,306 +/- 1,645) were similar in patients and controls. During dipyridamole administration, the rate pressure product increased similarly in both groups. Myocardial blood flow at rest did not differ between groups of patients and volunteers (0.69 +/ -0.27 v 0.67 +/- 0.17 mL/g/min) but correlated with the rate pressure product only in controls (myocardial blood flow, 0.18 + 0.000068214; rate pressure product, .67; P < .05). Hyperemic myocardial blood flow was lower in patients (1.57 +/- 0.39 v 1.92 +/- 0.31 mL/g/min, p < .05, whereas myocardial flow reserve did not differ between groups of patients and controls (2.57 +/- 1.15 v 3.02 +/- 0.94). Coronary vasodilatory capacity is reduced in patients with severe nonischemic cardiomyopathy. Increases in extravascular compressive forces or increased serum catecholamine levels, which in turn induce coronary vasoconstriction, might account for this finding.     

Klippel-Trenaunay-Weber syndrome with adrenal pseudocyst: characterization by blood pool and adrenocortical iodocholesterol scintigraphy

A 44-year-old woman with Klippel-Trenaunay-Weber syndrome (KTWS) was evaluated for an adrenal mass incidentally discovered on CT. An NP-59 scintigraph showed normal symmetric adrenal tracer uptake, and a Tc-99m labeled RBC scan showed no evidence for an adrenal hemangioma but did show characteristic dilated and tortuous vasculature at multiple other sites. The mass was removed and found to be an adrenal pseudocyst. The pseudocyst was believed to have arisen from a pre-existing, thrombosed and organized adrenal hemangioma. This case demonstrates the previously reported utility of RBC scintigraphy in the depiction of the vascular abnormalities in the diagnosis and treatment of patients with Klippel-Trenaunay-Weber syndrome, as well as the utility of NP-59 scintigraphy in evaluating patients with adrenal masses.     

Transient normalization of systolic and diastolic function after support with a left ventricular assist device in a patient with dilated cardiomyopathy

A 19-year-old man who had fulminant heart failure caused by an idiopathic dilated cardiomyopathy was supported with a left ventricular assist device for 183 days as a bridge to heart transplantation. At the time of intended transplantation it was noted that the patient's heart had returned to normal size, had a normal ejection fraction, and was able to maintain normal pressures and flows. In view of the apparent recovery of cardiac properties, the left ventricular assist device was explanted and the transplantation was not performed. However, the heart dilated, ejection fraction worsened, and the patient died of heart failure exacerbated acutely by a systemic viral illness. Although such recovery of systolic function is uncommon, as use of the left ventricular assist devices becomes more widespread other physicians might encounter similar findings and, in this regard, they might find our experience useful as they contemplate their treatment options.     

Temporary mechanical left heart support. Recovery of heart function in patients with end-stage idiopathic dilated cardiomyopathy

BACKGROUND: Implantation of a mechanical cardiac support system (MCSS) in patients with idiopathic dilated cardiomyopathy (IDC) may improve cardiac function and allow explantation of the device. Our experience now includes 13 patients who have been "weaned" from MCSS and we report about the overall results of this treatment as well as the effects of ventricular unloading on cardiac function, anti-beta 1-adrenoceptor-autoantibody (A-beta 1-AAB) level and the degree of myocardial fibrosis. METHODS: 13 patients with non-ischemic IDC who had been admitted here in cardiogenic shock (CI < 1.61.min-1.m2, left ventricular ejection fraction [LVEF] < 16% and left ventricular internal diameter in diastole [LVIDd] > 68 mm) and who all tested positive for A-beta 1-AABs were implanted with an uni-(12 patients) or a biventricular (1 patient) mechanical assist device. Echocardiographic evaluation and A-beta 1-AAB-level-monitoring was routinely performed after implantation and explantation of the MCSS and the degree of myocardial fibrosis was assessed at the time of implantation and after explantation. RESULTS: During a mean duration of mechanical support of 236 +/- 201 days (range: 30 to 794 days), LV-EF improved to a mean of 46% and LVIDd decreased to a mean value of 56 mm in these 13 patients. A-beta 1-AABs decreased and disappeared 11.7 weeks after implantation of the device and did not reincrease thereafter. The highly pathologic degree of fibrosis at the time of implantation diminished to normal values about 1 year after explantation. One patient died of anesthesiologic complications and another patient shortly presented with a new episode of cardiac insufficiency 6 months after explantation. He was implanted again with an univentricular assist device was successfully transplanted 3 weeks later. Mean observation period of the remaining 11 patients now amounts to 12.6 +/- 9.77 (range: 3 to 26) months after explantation of the device--as of May, 31, 1997--with a cumulative observation period of 139 patient months. CONCLUSION: Temporary implantation of a MCSS may normalize cardiac function in selected patients with IDC. The striking degree of myocardial fibrosis can reduce to normal values after explantation of the device. A-beta 1-AABs disappear during ventricular unloading and do not increase thereafter. "Weaning" from mechanical device may constitute an alternative treatment to cardiac transplantation in selected patients.     

Recovery of cardiac function by long-term left ventricular support in patients with end-stage cardiomyopathy

Effects of long-term left ventricular (LV) support on end-stage cardiomyopathy patients is unclear. We applied our LV assist system (LVAS) to six heart transplant candidates, aged 17 to 49, with dilated cardiomyopathy, including one dilated phase hypertrophied cardiomyopathy. LVAS was installed between the left atrium and the ascending aorta, and the pump was positioned parecorporeally. In all patients, their general condition improved, and their pump flows were kept at 4 to 5 L/min. Exercise was started after stabilization of their general condition under constant pump flow. Natural heart size and function were examined by echocardiography. In the beginning of assist, all patients showed impaired cardiac function and LV dilation. During LV assist, systolic function measured by ejection time improved in all patients. Left ventricular end-diastolic dimension (LVDd), showed a remarkable decrease in two patients, who were weaned from LVAS after 3 months of support. They are doing well more than 1 year and 3 years after removal; peak VO2 levels (ml/min/kg) were 30 at 1.2 years and 27 at 2.7 years after removal. In the other four patients, however, LVDd had no remarkable changes, and three could not be weaned from LVAS. The last was discontinued from LVAS after 5 months of support because of infection and died 2 months after removal. From this experience, long-term LVAS may provide the chance for recovery of the natural heart in patients with end-stage cardiomyopathy. The patients whose hearts showed remodeling were able to be weaned from LVAS, and their heart function maintained in good condition for several years.     

Effects of partial ventriculectomy on left ventricular mechanical properties, shape, and geometry in patients with dilated cardiomyopathy

This study evaluated the 6-month clinical response to sustained-release tetracycline fibers used alone or with scaling and root planing in 25 adult periodontal maintenance patients. All subjects had at least one pocket > or = 4.0 mm that bled on probing and required therapy. Thirty-six teeth were treated with tetracycline fibers for 7 to 12 days; twelve of the 36 teeth also received scaling and root planing. The selection of teeth for scaling and root planing was based on the condition of the teeth. Therapeutic results were evaluated by changes in probing depth and frequency of bleeding on probing. Use of tetracycline fibers and fibers with scaling produced 1.8- and 1.7-mm reductions in probing depth, respectively, 1 month after treatment; reductions declined to 1.3 and 0.8 mm at 3 months, but rebounded to 1.5 and 1.3 mm at 6 months. The percentage of teeth exhibiting bleeding on probing decreased from 100% at baseline to 68% and 50% in the fiber and fiber plus scaling groups, respectively, at 6 months. None of the differences was statistically significant. Tetracycline fibers clearly decreased clinical signs of periodontal inflammation. Addition of scaling and root planing at the time of fiber placement further decreased, although not significantly, the degree of inflammation.     

Chronic inflammation in the myocardium of patients with clinically suspected dilated cardiomyopathy

The beta-thymosins are a family of small proteins originally isolated from the thymus. Recently, two of the major mammalian isoforms, thymosin beta 4 (T beta 4) and thymosin beta 10 (T beta 10), are identified as significant actin monomer sequestering proteins which may be involved in regulating actin filament assembly. To study the cellular function of beta-thymosins, we have used isoform-specific antibodies to determine their concentration and intracellular distribution, and examined the effects of inducing overexpression of T beta 4 and T beta 10 on actin filament structures. Immunofluorescence labeling of peritoneal macrophages showed that both beta-thymosins are uniformly distributed within the cytoplasm. cDNA-mediated overexpression of beta-thymosins in CV1 fibroblasts induced extensive loss of phalloidin-stained actin stress fibers. Stress fibers in the cell center were more susceptible than those at the periphery. There was a decrease in the number of focal adhesions, as evidenced by a decrease in discrete vinculin staining and an increase in diffuse vinculin fluorescence. The majority of the transfected cells had normal shape in spite of extensive loss of actin filaments. Occasionally, cells overexpressing beta-thymosin were observed to divide. In these cells, beta-thymosin was excluded from the midbody which contains an actin filament-rich contractile ring. Our results indicate that T beta 4 and T beta 10 are functionally very similar and both are effective regulators of a large subset of actin filaments in living cells.     

Circannual variation of malignant ventricular tachyarrhythmias in patients with implantable cardioverter-defibrillators and either coronary artery disease or idiopathic dilated cardiomyopathy

We studied the possible relation between the frequency of ventricular tachyarrhythmic events and thermal stress in patients with an implantable cardioverter-defibrillator (ICD) living in a locally limited area under homogeneous climatic conditions. The frequency of tachyarrhythmic events was correlated with the thermal stress level according to the "Klima Michel Model," a complete thermophysiologic model that calculates "felt-temperature" values on the basis of the outdoor temperature and further meteorologic data. During a mean follow-up time of 40 +/- 17 months (range 4 to 72), 761 ventricular tachyarrhythmic events occurred in 50 of 138 consecutive ICD recipients. Analysis of the monthly felt-temperature levels and the mean circannual variation of the registered ventricular arrhythmias suggested that very cold and very hot conditions may be associated with an increased frequency of ventricular tachyarrhythmias. This finding was confirmed by calculation of the sum of tachyarrhythmias on all 2,039 days of the follow-up period divided into 5-degree-step felt-temperature classes. Thus, thermal stress may be 1 factor triggering the occurrence of ventricular tachyarrhythmias in patients with cardiac disease and suppressed cardiac function. Part of the increase in cardiac mortality under above-average hot and cold atmospheric conditions may be attributed to ventricular arrhythmic events.     

Ionic basis of the action potential prolongation in ventricular myocytes from Syrian hamsters with dilated cardiomyopathy

OBJECTIVE: The aim of our study was to determine the main electrophysiological alterations associated with cardiac dilation in MS200 strain Syrian hamsters, a model of genetically determined cardiomyopathy. METHODS: Ventricular action potentials (APs) were recorded with standard microelectrodes in isolated hearts from 120-day-old cardiomyopathic (strain MS200) and age-matched control (strain CHF148) Syrian hamsters. Ionic currents were recorded from single ventricular myocytes using the whole-cell patch-clamp technique. RESULTS: In MS200, AP was prolonged and the plateau phase was markedly increased as compared to CHF148. Differences in both AP duration and 4-aminopyridine-induced AP lengthening between epicardial and endocardial tissues were less marked in MS200 than in CHF148 ventricles. Cell size and membrane capacitance were not higher in MS200 than in CHF148 myocytes, indicating the absence of cell hypertrophy in myopathic ventricles. The L-type calcium current (ICa,L) density was significantly reduced in MS200 and the voltage-dependence of both steady-state activation and inactivation was altered. The voltage-dependent outward current was composed of both transient (Ito1) and sustained (Iss) components, respectively sensitive and insensitive to 4-aminopyridine. Ito1 density was strongly depressed in MS200 compared to CHF148, whereas Iss density was only slightly reduced. The conductance-voltage and steady-state inactivation relationships for Ito1 were shifted to more positive potentials in MS200. The Ito1 recovery process was markedly slower in MS200 than in CHF148. The steady-state current-voltage relationships, in the physiological voltage range, were superimposable in MS200 and CHF148. CONCLUSIONS: In ventricular myocytes from dilated heart of MS200 Syrian hamsters, Ito1 is more drastically depressed than ICa,L. Such an observation might partially explain dilation-induced AP lengthening.     

Combined study with FDG PET and Tl SPECT in patients with idiopathic dilated cardiomyopathy

This study aimed to determine whether combined examinations of myocardial 2-[18F]fluoro-2-deoxy-D-glucose positron emission tomography (FDG PET) and stress-redistribution 201Tl single-photon emission computed tomography (Tl SPECT) were useful in clarifying myocardial ischaemia and evaluating the prognosis in patients with idiopathic dilated cardiomyopathy (IDCM). Twenty-two patients with IDCM underwent echocardiography, cardiac catheterization, FDG PET, and Tl SPECT. In scintigraphic analysis, the total defect score (TDS) was semiquantitatively determined as the sum of scores of the 17 left ventricular (LV) segments with a 5-point scale (0 as normal to 4 as absent). Patients were classified according to the scintigraphic findings as follows: eight patients with small defects on Tl and FDG (TDS < or = 20) (group I), eight patients with small defects on FDG (TDS < or = 20) with FDG uptake increased relative to Tl or 'mismatch' (group II), and six patients with large defects on FDG and Tl (TDS >20) (group III). Eleven patients (50%) showed reversible defects on Tl and all showed preserved FDG uptake. The patients in group III had significantly lower LV ejection fraction (LVEF) (P<0.05, respectively) and a poorer prognosis as shown by the Kaplan-Meier event-free curve compared with those in groups I and II (P<0.01, respectively). Although patients in group II had significantly greater TDS on Tl compared with those in group I (P<0.01), no significant differences in LVEF and prognosis were found between patients in groups I and II. In multivariate analysis, a TDS on FDG revealed an independent predictor of subsequent cardiac events. In conclusion, such mismatched areas can be assumed to consist of impaired but viable myocardium, and may be associated with ischaemia of the microvasculature. Impaired myocardial glucose metabolism is a more powerful predictor of future cardiac events than perfusion abnormality in patients with IDCM.     

Partial left ventriculectomy with mitral valve preservation in the treatment of patients with dilated cardiomyopathy

OBJECTIVE: This study reports initial results of partial left ventriculectomy performed with preservation of the mitral valve in the treatment of 27 patients with idiopathic dilated cardiomyopathy. METHODS: Patients were in New York Heart Association class III or IV. Partial ventriculectomy was performed as an isolated procedure in four patients and associated with mitral annuloplasty in 23 patients. There were four hospital deaths (14.8%) and the remaining patients were followed for 11.2 +/- 6 months. RESULTS: Decrease of left ventricular diastolic diameter (81.8 +/- 8.7 to 68.5 +/- 7.6 mm, p < 0.001) and improvement of left ventricular wall shortening (12% +/- 3.1% to 18.1% +/- 3.9%, p < 0.001) were demonstrated by echocardiography after the operation. Left ventricular radioisotopic angiography showed reduction of diastolic volume (495 +/- 124 ml to 352 +/- 108 ml, p < 0.001) and increase of ejection fraction (17.7% +/- 4.6% to 23.7% +/- 8.8%, p < 0.001). Right-sided heart catheterization demonstrated improvement of stroke index (24.3 +/- 7.7 ml/m2 to 28.3 +/- 7.6 ml/m2, p < 0.01) and decrease of pulmonary wedge pressure (23.2 +/- 8.8 mm Hg to 17 +/- 7 mm Hg, p < 0.01). Similar results were documented at 6 and 12 months of follow-up. Functional class improved from 3.6 +/- 0.5 to 1.4 +/- 0.6 (p < 0.001). However, seven patients died at midterm follow-up because of heart failure progression or arrhythmia-related events, and survival rate was 59.2% +/- 9.4% from 6 to 24 months of follow-up. CONCLUSIONS: Partial left ventriculectomy performed with preservation of the mitral valve improves left ventricular function and congestive heart failure in patients with dilated cardiomyopathy. Nevertheless, the high incidences of heart failure progression and arrhythmia-related deaths observed after this procedure preclude its wide clinical application.