Attempt to prevent doxorubicin-induced acute human myocardial morphologic damage with acetylcysteine.

Doxorubicin induced acute as well as chronic myocardial morphologic alterations. Twenty patients with normal cardiovascular function were randomized to 2 groups based on age and dose of doxorubicin. Group I received placebo 1 hour before doxorubicin administration; group II received acetylcysteine (N-acetyl-L-cysteine) (Nac) 1 hour before doxorubicin. Endomyocardial biopsies were performed at base line at 4 and 24 hours after doxorubicin administration. Biopsy tissue was viewed by electron microscopy, and stereoscopic techniques were used to determine tubular and mitochondrial area. The change of the tubular area was similar in the 2 groups, was maximum at 4 hours, and was proportionately spread throughout the cell. The mitochondrial swelling was also similar in the 2 groups and proportionate throughout the cell but was maximum at 24 hours. This study demonstrated that the acute doxorubicin-induced damage was diffuse and not prevented by Nac.

Dobutamine and hydralazine: comparative influences of positive inotropy and vasodilation on coronary blood flow and myocardial energetics in nonischemic congestive heart failure.

Coronary blood flow and myocardial energetics were assessed after the administration of a parenteral inotrope (dobutamine hydrochloride) and an oral vasodilator agent (hydralazine) in 10 patients with nonischemic congestive heart failure. Dobutamine (5 micrograms/kg per min) and hydralazine (1 mg/kg) when group-matched elicited an identical increase in cardiac index and stroke volume index. Both agents augmented coronary blood flow while reducing coronary vascular resistance. Both forms of therapy elicited a significant increase in myocardial oxygen consumption. Dobutamine, demonstrating a balanced effect on the coronary circulation, induced a proportional increase in coronary blood flow and myocardial oxygen consumption, with the arterial-venous oxygen difference across the coronary vascular bed remaining unchanged. Hydralazine enhanced the myocardial oxygen supply versus demand ratio; despite a significant increase in myocardial oxygen consumption, the arterial-venous oxygen difference and the myocardial extraction ratio diminished. Both forms of therapy enhanced cardiac performance without inducing any electrocardiographic or clinical evidence of ischemia. Dobutamine, a positive inotropic agent, elicited a balanced effect on the coronary circulation while hydralazine, a vasodilator agent, induced a greater increase in coronary flow than in myocardial oxygen demand.

Comparison of front-loaded recombinant tissue-type plasminogen activator, anistreplase and combination thrombolytic therapy for acute myocardial infarction: results of the Thrombolysis in Myocardial Infarction (TIMI) 4 trial.

OBJECTIVES: The aim of our study was to determine a superior thrombolytic regimen from three: anistreplase (APSAC), front-loaded recombinant tissue-type plasminogen activator (rt-PA) or combination thrombolytic therapy. BACKGROUND: Although thrombolytic therapy has been shown to reduce mortality and morbidity after acute myocardial infarction, it has not been clear whether more aggressive thrombolytic-antithrombotic regimens could improve the outcome achieved with standard regimens. METHODS: To address this issue, 382 patients with acute myocardial infarction were randomized to receive in a double-blind fashion (along with intravenous heparin and aspirin) APSAC, front-loaded rt-PA or a combination of both agents. The primary end point "unsatisfactory outcome" was a composite clinical end point assessed through hospital discharge. RESULTS: Patency of the infarct-related artery (Thrombolysis in Myocardial Infarction [TIMI] grade 2 or 3 flow) at 60 min after the start of thrombolysis was significantly higher in rt-PA-treated patients (77.8% vs. 59.5% for APSAC-treated patients and 59.3% for combination-treated patients [rt-PA vs. APSAC, p = 0.02; rt-PA vs. combination, p = 0.03]). At 90 min, the incidence of both infarct-related artery patency and TIMI grade 3 flow was significantly higher in rt-PA-treated patients (60.2% had TIMI grade 3 flow vs. 42.9% and 44.8% of APSAC- and combination-treated patients, respectively [rt-PA vs. APSAC, p < 0.01; rt-PA vs. combination, p = 0.02]). The incidence of unsatisfactory outcome was 41.3% for rt-PA compared with 49% for APSAC and 53.6% for the combination (rt-PA vs. APSAC, p = 0.19; rt-PA vs. combination, p = 0.06). The mortality rate at 6 weeks was lowest in the rt-PA-treated patients (2.2% vs. 8.8% for APSAC and 7.2% for combination thrombolytic therapy [rt-PA vs. APSAC, p = 0.02; rt-PA vs. combination, p = 0.06]). CONCLUSIONS: Front-loaded rt-PA achieved significantly higher rates of early reperfusion and was associated with trends toward better overall clinical benefit and survival than those achieved with a standard thrombolytic agent or combination thrombolytic therapy. These findings support the concept that more rapid reperfusion of the infarct-related artery is associated with improved clinical outcome.

Postural influences on the hemodynamic responses to vasodilating drugs in congestive heart failure.

Supine and upright hemodynamic measurements were performed in 58 patients with congestive heart failure to assess the effects of postural change on the hemodynamic responses to vasodilating drugs. The patient population was divided into three treatment groups and was studied before and after isosorbide dinitrate, nifedipine, or clonidine treatment. When the hemodynamic responses in the upright position were compared with the supine values, isosorbide dinitrate (40 mg orally) evoked a greater reduction in mean systemic blood pressure and stroke volume with augmented increases in heart rate, mean pulmonary artery pressure, and pulmonary vascular resistance while the patient was upright. Nifedipine (10 mg orally) when studied in the upright position caused additional augmentation of cardiac output and stroke volume index with further reduction in total systemic vascular resistance compared with supine values. No position-related changes in hemodynamic measurements were noted with clonidine (0.1 mg orally).

Hydralazine therapy in chronic congestive heart failure. Sustained central and regional hemodynamic responses.

Central and regional hemodynamic parameters were evaluated at baseline and following three months of placebo or hydralazine therapy (100 mg orally every eight hours) in 20 patients with idiopathic dilated cardiomyopathy. Both control (placebo) and hydralazine groups were comparable with respect to functional classification (New York Heart Association classes III and IV) and baseline hemodynamic variables. In the hydralazine group, cardiac index increased 25 percent (2.4 +/- 0.4 to 3.0 +/- 0.5 liters/minute/m2), renal blood flow increased 26 percent (648 +/- 199 to 815 +/- 229 ml/minute), and limb blood flow was augmented by 35 percent (6.8 +/- 3.0 to 9.2 +/- 4.6 ml/dl/minute) with long-term therapy. These changes were significant (all p less than 0.05) when compared with both baseline values and values in the control group. Both central and regional hemodynamic parameters remained unaltered in the control group. Long-term hydralazine therapy (three months) elicited a favorable circulatory response in this group of patients with chronic congestive heart failure. Central or regional hemodynamic tolerance to oral hydralazine failed to develop in the majority of patients.

Electrophysiologic studies of perphenazine and protriptyline in a patient with psychotropic drug-induced ventricular fibrillation.

A 51 year old woman sustained ventricular fibrillation while receiving perphenazine and protriptyline. After successful resuscitation and clinical stabilization, cardiac electrophysiologic studies were performed before and after the administration of each of these medications. Perphenazine widened the ventricular echo zone and facilitated induction of short salvoes of ventricular tachycardia (repetitive ventricular response). Protriptyline also widened the ventricular echo zone and allowed easy induction of long runs of ventricular tachycardia. Both psychotropic agents increased the incidence of ventricular dysrhythmias in this patient. The electrophysiologic study is a useful technique in determining the interaction between psychotropic drugs and life-threatening arrhythmias; it may provide a means of identifying the patients with cardiac disease in whom administration of these agents may be fatal.

Hemodynamic effects of vasodilator therapy in severe left heart failure combined with large atrial septal defects.

Two patients presented with severe left heart failure and large secundum atrial septal defects without severe pulmonary hypertension. The acute hemodynamic effects of two commonly used vasodilator agents, isosorbide dinitrate and hydralazine, are described. Although isosorbide dinitrate improved systemic forward cardiac output, it also increased left-to-right intracardiac shunting in both patients. On the other hand, hydralazine dramatically improved systemic toward output and concomitantly diminished left-to-right shunt flow in each patient (43 and 21 percent). The complexities of combined severe left ventricular failure and a large atrial septal defect with left-to-right shunting, and the importance of extensive hemodynamic monitoring at the time of pharmacologic intervention, are discussed.

Influence of exercise on coronary sinus blood flow determinations.

Consecutively measured values of coronary sinus blood flow were compared to assess the reproducibility of the coronary sinus thermodilution technique. Values measured at rest and during exercise were evaluated and the influence of the respiratory cycle on reproducibility was studied. Correlation of consecutive values revealed a coefficient of 0.94 at rest and 0.93 during exercise. Differences between mean values of consecutive measurements were nonsignificant. A comparison of the coefficients of variation at rest (8.50 +/- 7.09) and exercise (8.02 +/- 4.75) revealed no significant difference. Variation about mean coronary sinus blood flow due to inspiration and expiration was similar at rest and during exercise (42% and 37%, respectively). Provided that critical variables are closely monitored, the coronary sinus thermodilution technique is a highly reproducible technique in a clinically feasible setting.

Rest and exercise cardiovascular effects of terazosin in congestive heart failure.

This study investigated the acute effects of the alpha 1 antagonist terazosin on myocardial circulatory responses at rest and during exercise. Ten patients with congestive heart failure (class III and IV) underwent hemodynamic evaluation before and after a 5-mg oral dose of terazosin. At rest and during exercise, terazosin significantly decreased pulmonary capillary wedge pressure, systemic vascular resistance and mean arterial pressure while cardiac index increased. Stroke volume index increased (p less than 0.01) during exercise while left ventricular stroke work index remained unchanged in both experimental conditions. Terazosin administration significantly decreased both rest and exercise myocardial oxygen consumption while exercise coronary sinus oxygen content increased and arterial-coronary sinus oxygen difference diminished (p less than 0.05). Parallel with these changes, alpha blockade decreased the ratio of coronary blood flow to total cardiac output. Coronary vascular resistance remained unaltered with alpha blockade both at rest and during exercise. Coronary blood flow tended to diminish with decreased myocardial oxygen demand. Alpha 1 blockade induces systemic vasodilation and improves myocardial circulatory parameters without inducing coronary dilation or altering metabolic autoregulation.

Clonidine in congestive heart failure: a vasodilator with negative inotropic effects.

Fourteen patients with moderately severe congestive heart failure (CHF) were given clonidine orally (0.2 and 0.4 mg doses) to determine the hemodynamic effects of a typical centrally acting vasodilator. The 0.2 mg dose significantly reduced mean systemic (15%) and mean pulmonary artery (20%) pressure; the corresponding reductions in vascular resistance were not as great because of a diminished cardiac output. Pulmonary capillary wedge pressure decreased significantly (27%). Heart rate decreased 11% and stroke volume remained unchanged. At a higher dose (0.4 mg), clonidine augmented these reductions but increased stroke volume modestly (15%). Isovolumic developed pressure/duration of isovolumic contraction and the duration of the preejection period were used as indexes of inotropy. After both doses, isovolumic developed pressure/duration of isovolumic contraction decreased dramatically (greater than or equal to 33%) and the preejection period increased substantially (greater than or equal to 18%) (both p less than 0.05). Compared with currently employed vasodilating agents, the centrally acting agent clonidine appears unique in that the drug-induced systemic and pulmonary arterial vasodilation are not accompanied by a commensurate improvement in ventricular systolic function. This lack of improvement appears to be a result of negative inotropic effects.

Regression of myocardial cellular hypertrophy with vasodilator therapy in chronic congestive heart failure associated with idiopathic dilated cardiomyopathy.

Forty-nine patients with idiopathic dilated cardiomyopathy (IDC) were evaluated to determine the hemodynamic and morphologic effects of vasodilator therapy. Hydralazine (225 mg/day, H), isosorbide dinitrate (160 mg/day, I), and combination H + I therapy were compared with placebo (P) at baseline and after 3 months of continuous therapy. Thirty-three randomly assigned patients completed the study. Hemodynamic parameters included the echocardiographic percent change of left ventricular diameter (% delta D), the systolic time intervals ratio of preejection period to left ventricular ejection time (PEP/LVET), the pulmonary capillary wedge pressure, mean pulmonary artery pressure, cardiac index, systemic vascular resistance, and pulmonary vascular resistance. An endomyocardial biopsy was performed at baseline and after 3 months; the myocardial cell diameter of 50 cells per biopsy was measured. During the 3-month study 5 patients died; there was not a significant difference among the groups in the number of deaths. The % delta D and PEP/LVET did not change in the P or I groups but did improve significantly from baseline in the H and H + I groups. The pulmonary capillary wedge and mean pulmonary artery pressures and the pulmonary vascular resistance did not change in the P or H groups but did decrease significantly in the I and H + I groups. The P and I groups did not have improvement in systemic vascular resistance or cardiac index, whereas the H group had a decrease in systemic vascular resistance and an increase in cardiac index from 2.5 +/- 0.4 to 3.1 +/- 0.4 liters/min/m2 (p less than 0.05). The H + I group also had a decrease in systemic vascular resistance; the cardiac index increased from 2.3 +/- 0.4 to 3.1 +/- 0.4 liters/min/m2 (p less than 0.01). Myocardial cell diameter did not change in the P or I group. Cell diameter of the H group decreased from 25.4 +/- 3.1 microns at baseline to 23.1 +/- 3.8 microns (p less than 0.05) after 3 months of continuous therapy. The H + I group decreased its cell diameter from 23.9 +/- 3.7 to 22.2 +/- 2.2 microns (p less than 0.05). Compared with P and H, patients treated with I alone or H + I had a significant reduction of preload. In contrast to P and I, H alone and H + I elicited improvement in parameters of inotropy and afterload, and this improvement was accompanied by a reduction in cell diameter. Chronic therapy of heart failure with H and H + I effects a persistent augmentation of cardiac function and improvement of myocardial cellular morphology.

Interatrial conduction (activation) times.

Left atrial electrograms were recorded simultaneously from sites located in the coronary sinus, right pulmonary artery and esophagus in order to determine and correlate the interatrial conduction times obtained from these locations. Ten patients with normal-sized atria and 16 patients with isolated left atrial enlargement were studied. A high correlation existed between the P wave duration and the interatrial conduction times obtained from the coronary sinus and pulmonary artery; good correlations were also found for the interatrial conduction times recorded from the pulmonary artery and esophagus correlated well with those recorded from the distal coronary sinus (the generally accepted standard for the indirect interatrial conduction time measurements). In addition to providing information on the mechanism of atrial arrhythmias, the electrograms obtained from the various indirect left atrial recording sites provide satisfactory quantification of interatrial conduction.

Development of pharmacodynamic tolerance to prozosin in congestive heart failure.

In order to determine and compare the pharmacodynamic responses to single and multiple dose prazosin therapy in cardiac failure, 14 patients with severe low-output heart failure underwent central and regional hemodynamic measurements after random placement in one of two prazosin dosing schedules. A single 5 mg oral dose of prazosin (Group A, no. = 7) significantly increased the cardiac index and stroke volume index while significantly decreasing systemic, pulmonary and pulmonary capillary wedge pressures and vascular resistances. Hepatic plasma flow and limb blood flow increased after the single dose. Striking attenuation of these hemodynamic effects occurred when the same dose was administered after 24 hours of pretreatment with oral prazosin, 2 mg every 8 hours (Group B, no. = 7). The plasma prazosin levels of the two groups, drawn 2 hours after administration, were 24.5 and 30.5 ng/ml, respectively. Repeated administration of prazosin in patients with congestive heart failure results in rapid attenuation of its beneficial central and regional hemodynamic effects. The usefulness of this vasodilator as a preload- and afterload-reducing agent in the clinical setting of chronic congestive heart failure may be limited by the development of pharmacodynamic tolerance.

Factors influencing the one-year mortality of dilated cardiomyopathy.

This study was designed to determine prognostic risk indicators of nonischemic dilated cardiomyopathy (DC). Sixty-nine patients were studied. Each patient underwent physical examination (including a history), electrocardiography, echocardiography, cardiac catheterization, 24-hour monitoring and endomyocardial biopsy. The mortality rate at 1 year was 35% (24 deaths). Univariate analysis revealed that the most powerful predictor of prognosis was the left intraventricular conduction delay (p = 0.003). The pulmonary capillary wedge pressure was also predictive of mortality (p = 0.005). Other significant factors, in order of importance, were ventricular arrhythmias (p = 0.007), mean right atrial pressure (p = 0.008), angiographic ejection fraction (p = 0.03), atrial fibrillation or flutter (p = 0.01) and the presence of an S3 gallop (p = 0.05). Factors such as duration of symptoms, presence of mitral regurgitation, end-diastolic diameter, myocardial cell size and percent fibrosis in the biopsy and treatment with vasodilators, antiarrhythmic and anticoagulant drugs were not significant predictors. Multivariate analysis was used to determine which combination of factors could most accurately predict survival and death. The most important factors were left conduction delay, ventricular arrhythmias and mean right atrial pressure. An equation was derived that can be applied to the prognosis of patients with DC. Thus, the clinical assessment of patients with DC can accurately predict the probability of surviving or dying in 1 year.

Amrinone therapy for congestive heart failure in outpatients with idiopathic dilated cardiomyopathy.

Amrinone, 100 mg orally every 8 hours, was administered to 13 patients with moderate-to-severe congestive heart failure (CHF) for 1 month on an outpatient basis to determine the beneficial and undesirable effects of this new cardioactive agent in this clinical setting. These subjects received conventional CHF medications during the course of study. Ten patients who received conventional CHF medications alone served as a control group. Changes in functional classification were not significantly different between the 2 treatment groups. Amrinone augmented exercise capacity 37% above baseline compared with a 12% improvement for the control group. Noninvasive indexes of resting left ventricular function (echocardiography and systolic time intervals) did not change significantly for either group, nor was there a significant change in the exercise ejection fraction. All patients treated with amrinone had greater than or equal to 1 symptom-related or laboratory-detected adverse effect. An increase in the frequency of ventricular ectopic beats was noted at rest in 4 and with exercise in 6 patients (salvos of nonsustained ventricular tachycardia in 2). Six subjects treated with amrinone had gastrointestinal symptoms and 8 developed a viral-like illness. Other adverse effects noted in the amrinone-treated group included near-syncope, headaches, marked anxiety, chest pain, palpitations, maculopapular rash, hypokalemia, and elevation of serum transaminase levels. The control patients had significantly fewer adverse effects. Although individual patients with CHF may benefit from long-term amrinone therapy, the low benefit-to-risk-adverse effect ratio does not warrant widespread application of this drug in the outpatient management of CHF and requires caution when prescribing.

Positive inotropic effects of hydralazine in human subjects: comparison with prazosin in the setting of congestive heart failure.

Hydralazine possesses positive inotropic properties in animal model preparations. To determine whether this vasodilator elicits a positive inotropic response in the failing human ventricle, hydralazine, 75 or 100 mg, was administered orally to 14 patients with left ventricular dysfunction and congestive heart failure; the results were compared with those of first-dose prazosin at 5 and 10 mg. The duration of the preejection period and the isovolumic developed pressure/duration of isovolumic contraction (delta P/delta t) were used as indexes of inotropy. Prazosin did not effect a significant response in the duration of the preejection period or in the delta P/delta t. Hydralazine significantly shortened the preejection period and increased the delta P/delta t over 8 hours after administration; these data suggest that hydralazine elicits a positive inotropic response in the failing human ventricle.

Hemodynamic correlates for timing intervals, ejection rate and filling rate derived from the radionuclide angiographic volume curve.

This study was designed to more clearly define the relation between various invasive hemodynamic measurements and left ventricular (LV) timing intervals, ejection rate and filling rate derived from the radionuclide angiographic volume curve. Twenty-eight patients were studied with simultaneous intracardiac micromanometer pressure and dP/dt recordings, gated radionuclide angiography and M-mode echocardiography. These techniques permitted multiple variables of systolic and diastolic function to be measured at a constant atrial paced rate of 100 beats/min. There was a strong correlation between peak ejection rate and ejection fraction (r = -0.97) and between peak ejection rate and maximum positive dP/dt (r = -0.85). There also was a strong correlation between peak filling rate and maximum negative dP/dt (r = -0.85). A weaker correlation existed between the time constant of LV relaxation and the peak filling rate (r = -0.49) and between the LV end-diastolic pressure and the peak filling rate (r = -0.62). There was no correlation between the modulus of chamber stiffness and filling rates, and no association was observed between the time to peak filling rate and the hemodynamic variables. Thus, under the conditions studied, the measured peak ejection and filling rate, determined from the radionuclide angiographic volume curve, correlated well with accepted invasive hemodynamic measurements.

Poloxamer-188 as an adjunct to primary percutaneous transluminal coronary angioplasty for acute myocardial infarction.

Poloxamer-188 is a surfactant polymer with antithrombotic and hemorheologic properties that make it potentially useful as an adjunct to acute reperfusion strategies. Animal studies and early human studies have documented poloxamer-188 to be effective at improving myocardial salvage when used as an adjunct to intravenous thrombolytic therapy for acute myocardial infarction. The current trial was a prospective pilot study involving 150 patients who were randomized in a 2:1 fashion to a poloxamer-188 infusion for 48-hours versus placebo. The poloxamer-188 infusion was well tolerated subjectively. The only clinically significant laboratory abnormality noted was an elevation in the serum creatinine above 2.0 g/dl in 12% (n = 12) of the 98 poloxamer-188 treated patients versus 1 of the 52 (2%) of the placebo treated patients (p = 0.048). Clinical end points including reinfarction (1% vs 4%), cardiogenic shock (7% vs 6%), and death (9% vs 4%) were statistically similar in the poloxamer-188 and placebo groups, respectively (p = NS). Using quantitative nuclear techniques, final infarct size and myocardial salvage were statistically similar in the poloxamer-188 and placebo groups. Mean left ventricular ejection fractions 1 week post after infarction were 51% +/- 12% in the poloxamer-188 group and 52% +/- 13% in the placebo group (p = NS). Final infarct size, was not altered by the poloxamer- 188 infusion; however, it was significantly correlated with normal perfusion (Thrombolysis in Myocardial Infarction grade 3 flow) in the infarct vessel after angioplasty. This study documented poloxamer-188 to be ineffective as an adjunct to primary angioplasty for acute myocardial infarction and resulted in azotemia in 12% of the patients.

Myocardial infarct artery patency and reocclusion rates after treatment with duteplase at the dose used in the International Study of Infarct Survival-3. Burroughs Wellcome Study Group.

Duteplase, 98% double-chain recombinant tissue-type plasminogen activator, was administered intravenously in 488 patients with acute myocardial infarction in a multicenter, open, safety and patency study. Duteplase dosing was based on body weight. Duteplase was administered as a bolus of 0.04 MIU/kg of thrombolytic activity followed by 0.36 MIU/kg over 1 hour and 0.067 MIU/kg/hour for 3 additional hours. The patency rate of the infarct-related artery at 90 minutes was 69% (330 of 478). The reocclusion rate at 3 to 48 hours was 6% (18 of 301). Reinfarction occurred in 7.6% of patients (37 of 488), but 12 reinfarctions occurred after coronary angioplasty. Serious bleeding occurred in 7.6% of patients (37 of 488), predominantly at the catheterization entry site. There were 3 instances of central nervous system bleeding, 1 fatal. Fibrinogen levels declined to 83% of baseline at 24 hours. Weight-based dosing may explain the low incidence of serious bleeding in this study. The in-hospital mortality was 6.6% (32 of 488). This study documents that the dose of duteplase used in the International Study of Infarct Survival-3 results in a 90-minute coronary artery patency rate and safety profile comparable to those reported in published studies on the approved dose of alteplase.

Differentiating characteristics of myocardial nuclei in cardiomyopathy.

Myocardial tissue obtained by endomyocardial biopsy was semiquantitatively evaluated for nuclear and nucleolar characteristics in six groups of patients: patients with normal cardiac function (group 1), doxorubicin-induced cardiomyopathy (group 2), idiopathic cardiomyopathy (group 3), alcoholic cardiomyopathy (group 4), post-viral cardiomyopathy (group 5), and chronic valvular heart disease (group 6). From each patient, ten nuclei containing nucleoli were examined and rated on the basis of the following characteristics: chromatin clumping, number of fibrillar centers per nucleolus, nucleolonemal structure, size of nucleolus, number of nucleoli per nucleus, and stage of nucleolar change. Mean values for the nuclear characteristics in each group were compared with normal values using the unpaired t test. In the doxorubicin treated group there were significantly increased chromatin clumping, decreased fibrillar centers, decreased nucleolonemal structure, and increased numbers of contracted nucleoli (indicating later stage). These changes may be linked to lowered nuclear and nucleolar activity. In the idiopathic and post-viral groups, characteristics were consistent with increased nuclear and nucleolar activity. There were no significant changes from normal in the nucleolar features of either the alcoholic or valvular groups. Further comparisons between groups using one-way analysis of variance and multivariate statistical analysis support the conclusion that there are significant differences in the nuclear and nucleolar characteristics of these groups.