Exercise first-pass radionuclide assessment of left and right ventricular function and valvular regurgitation in symptomatic mitral valve prolapse

The changes in right ventricular (RV) and left ventricular (LV) function and in regurgitant fractions on first-pass exercise radionuclide angiography (RNA) were assessed in 29 consecutive patients with symptomatic mitral valve prolapse (MVP). The mean right ventricular ejection fraction (RVEF) was 35 +/- 8% at rest and 46 +/- 15% after exercise (p less than 0.001). The mean left ventricular ejection fraction (LVEF) was 62 +/- 11% at rest and 74 +/- 13% after exercise (p less than 0.001). Seven of 29 patients had an abnormal RV response and 6 had an abnormal LV response. Eight had abnormal wall motion after exercise. A total of 12/29 patients (41%) had one or more abnormalities. The mean left-sided regurgitant fraction before exercise was 27 +/- 17% in 21/29 patients (72%) and 31 +/- 21% after exercise (p = ns). An additional 5 patients (17%) developed left-sided regurgitation after exercise. These findings indicate that wall motion abnormalities and abnormal RVEF and LVEF responses to exercise occur in symptomatic MVP patients. In addition, 26/29 (89.6%) had left-sided regurgitation after exercise. Since the presence of a murmur did not correlate with the presence of mitral regurgitation by RNA, then symptomatic patients with MVP should have first-pass exercise RNA to assess the presence of regurgitation at rest and after exercise. Antibiotic prophylaxis is recommended in MVP patients with systolic murmurs or with regurgitation. Since patients without murmurs can have regurgitation, further study is necessary to determine the need for endocarditis prophylaxis in these patients.     

Detection of exercise induced changes in left ventricular performance by Doppler echocardiography.

A study was performed to test the hypothesis that Doppler echocardiographic measurement of ascending aortic blood flow can detect exercise induced changes in left ventricular performance during exercise in patients suspected of having ischaemic heart disease. Acceleration and peak velocity of flow and stroke volume were determined by non-imaging Doppler echocardiography in the suprasternal notch in 38 patients as they underwent simultaneous exercise radionuclide ventriculography. The patients were divided into four groups: group 1 had resting ejection fractions greater than or equal to 50% and increased their ejection fractions greater than or equal to 5% during exercise; group 2 had resting ejection fractions of greater than or equal to 50% but the ejection fraction either fell or rose less than 5% during exercise; group 3 had resting ejection fractions less than 50% but the ejection fraction rose greater than or equal to 5% during exercise; and group 4 had resting ejection fractions less than 50% and the exercise ejection fraction either fell or rose less than 5% during exercise. Acceleration, velocity, and stroke volume all rose significantly during exercise in group 1. Acceleration also increased in group 2 but to a lesser extent; velocity and stroke volume did not increase. In group 3 acceleration and velocity increased but to a lesser extent than in group 1; stroke volume did not increase. In group 4 velocity increased slightly during exercise but acceleration and stroke volume were unchanged. Doppler echocardiography thus appears capable of detecting exercise induced changes in left ventricular performance and can identify normal and abnormal responses, as defined by radionuclide ventriculography.     

Effects of severity of mitral stenosis on left and right ventricular function at rest and during exercise

Few studies have assessed the effect of severity of mitral stenosis (MS) on ventricular function. Using equilibrium radionuclide ventriculography to measure ejection fraction and volume changes, 63 patients were studied during supine, symptom-limited exercise. To more carefully assess the 12 patients with MS and impaired left ventricular function, 2 groups of patients were formed. Group I (n = 51) had a normal (less than 50%) resting left ventricular (LV) ejection fraction (EF) and group II (n = 12) had an abnormally low (less than 50%) resting LVEF. Both groups were divided into mild (greater than 1.4 cm2), moderate (1.1-1.4 cm2) and severe (less than 1.0 cm2) MS. There were no differences in mean rest or exercise LVEF for group I. Exercise LVEF increased significantly (p less than 0.05) from rest with mild MS, but not with moderate or severe MS. The decrease in exercise LVEF was due to a decrease in exercise end-diastolic volume of 9 +/- 23% and 15 +/- 18% for moderate and severe MS, respectively. Exercise end-systolic volume decreased normally for all degrees of MS severity. Exercise right ventricular (RV)EF did not increase for any degree of MS severity due to an increase in end-systolic volume. All patients in group II had an RVEF of less than 40%. For this group, severity of MS had no effect on resting LVEF and the response to exercise was similar to group I. We conclude that in patients with MS, resting LVEF is unaffected by MS severity whereas exercise LVEF decreases with increased severity of MS due to impaired diastolic filling.(ABSTRACT TRUNCATED AT 250 WORDS)     

Evaluation of right ventricular function in patients with idiopathic dilated and ischemic cardiomyopathy by equilibrium radionuclide ventriculography

We performed equilibrium radionuclide ventriculography in 12 patients with idiopathic dilated cardiomyopathy, 11 patients with ischemic cardiomyopathy and 11 normal subjects to determine whether measurements of right ventricular function could be used to distinguish dilated cardiomyopathy from ischemic cardiomyopathy. The left ventricular ejection fraction in patients with dilated cardiomyopathy (26 +/- 8%, mean +/- SD) or ischemic cardiomyopathy (32 +/- 5%) was significantly lower than in normals (69 +/- 6%, p less than 0.001). The right ventricular ejection fraction (RVEF) in normals was 57 +/- 7%. RVEF was decreased in 11 of 12 patients with dilated cardiomyopathy and the mean value (32 +/- 10%) was significantly lower than that in patients with ischemic cardiomyopathy (56 +/- 7%, p less than 0.001), none of whom had decreased RVEF. Our data show that right ventricular dysfunction commonly exists in patients with dilated cardiomyopathy but not in patients with ischemic cardiomyopathy. This finding may be useful in the differentiation between dilated and ischemic cardiomyopathy.     

Prognostic significance of right ventricular ejection fraction following inferior myocardial infarction

The prognostic significance of right ventricular ejection fraction, measured by radionuclide ventriculography, was assessed in 168 consecutive patients with inferior myocardial infarction. Right ventricular ejection fraction was 0.40 or less in 35 patients. Over a follow-up period of 40 months, there were 15 deaths in the total group of 168 patients, eight (23%) in the 35 with right ventricular ejection fraction of 0.40 or less, and seven (5%) in the remainder of the group. The one year survival of patients with right ventricular impairment (84 +/- 6%) was significantly worse (P less than 0.01) than those with a right ventricular ejection fraction over 0.40 (95 +/- 2%). A multivariate Cox model analysis showed age (P less than 0.001), left ventricular ejection fraction (P less than 0.01), and right ventricular ejection fraction (P less than 0.03) to be independent predictors of survival. Impaired right ventricular function is an adverse prognostic factor in patients with inferior infarction, particularly in those with impaired left ventricular function.     

Hemodynamically important right ventricular infarction: follow-up evaluation of right ventricular systolic function at rest and during exercise with radionuclide ventriculography and respiratory gas exchange

The prognosis and recovery of right ventricular systolic function in patients with hemodynamically documented right ventricular myocardial infarction (RVMI) is unclear. Therefore 27 patients who met hemodynamic criteria for RVMI were followed for at least 1 year. Four patients died within 1 year and 23 survived. Postmortem examination performed in three of the four patients showed extensive infarction of the right and left ventricles. Survivors underwent early and late follow-up resting radionuclide ventriculograms and late exercise studies. During long-term follow-up (1 to 4 years) resting radionuclide ventriculography demonstrated a significant improvement in right ventricular ejection fraction (30 +/- 7% to 43 +/- 8%; p less than .001) and right ventricular wall motion index (2.2 +/- 0.4 to 1.5 +/- 0.5; p less than .001) in 18 patients who survived longer than 1 year. Fourteen of these patients underwent upright bicycle exercise while off beta-blocking drugs and peak radionuclide ejection fraction was acquired after anaerobic threshold was achieved. Right ventricular ejection fraction increased significantly from 41 +/- 10% to 47 +/- 12% (p less than .001), as did the left ventricular ejection fraction (55 +/- 15% to 60 +/- 12%; p less than .05). The direction and magnitude of change of the right ventricular ejection fraction correlated significantly with the left ventricular ejection fraction (r = .82, p less than .02). Deviations from this correlation occurred in patients who had a decreased forced expiratory volume in 1 sec and an abnormal ventilatory reserve during exercise.(ABSTRACT TRUNCATED AT 250 WORDS)     

Response of the right ventricle to exercise in isolated mitral stenosis

Eight patients in sinus rhythm, with varying degrees of isolated mitral stenosis (mitral valve area 0.6 to 1.3 cm2 and total pulmonary vascular resistance 5.0 to 17.5 U-m2), underwent supine rest and symptom-limited exercise radionuclide ventriculography to determine right ventricular (RV) and left ventricular ejection fraction (EF). Cardiac catheterization with hemodynamic measurements at rest and at peak exercise was performed within 24 hours of radionuclide ventriculography. Four of the 8 patients underwent corrective mitral surgery resulting in normal mean pulmonary artery pressures and total pulmonary vascular resistance at rest. These 4 patients had repeat radionuclide ventriculography at rest and during exercise 1 to 2 months after surgery. Preoperatively, all 8 patients had an abnormal exercise RVEF response (mean change +/- standard deviation [SD], -5.0 +/- 4.5%), coincident with an increase in mean pulmonary artery pressure during exercise (mean change, 15 +/- 5.0 mm Hg). The change in RVEF from rest to exercise, corrected for duration of exercise, correlated with peak exercise mean pulmonary artery pressure (r = -0.71, p = 0.05), as well as total pulmonary vascular resistance at rest (r = -0.82, p = 0.02). Postoperatively, all 4 patients who underwent surgical correction showed a normal RVEF response during exercise (mean change +/- SD, +6.8 +/- 4.0%). Thus, in patients with acquired mitral stenosis and no coronary artery disease (1) loading conditions and not contractility are prime determinants of RV exercise response, and (2) an exercise-induced decrease in RVEF may be a sensitive marker for increased total pulmonary vascular resistance and pulmonary hypertension.     

High prevalence of right ventricular systolic dysfunction in early systemic sclerosis

OBJECTIVE: To assess right ventricular (RV) function in patients with early systemic sclerosis (SSc) and the acute effects of calcium channel blockers on RV ejection fraction (RVEF). METHODS: Forty-two consecutive patients with SSc with less than 5 years' disease duration and normal pulmonary arterial pressure (35 women, 7 men; mean age 54.3 +/- 9.7 years; 16 with diffuse and 26 with limited cutaneous forms, systolic pulmonary arterial pressure 30.3 +/- 5.4 mmHg) were prospectively evaluated. All underwent pulmonary function testing, echocardiography, and radionuclide ventriculography at rest and 2 hours after receiving 40 mg oral nicardipine, and were compared at baseline with 20 gender and age matched controls. RESULTS: None of the patients with SSc had clinical evidence of heart failure. At baseline, SSc patients had significantly lower LVEF (68.5% +/- 7.9 vs 72.4% +/- 5.0, p = 0.049) and RVEF (36.5% +/- 7.0 vs 45.8% +/- 5.7, p < 0.0001). Sixteen patients had reduced RVEF (< 35%), 3 had reduced LVEF (< 55%), and 10 had reduced peak filling rate (PFR). RVEF correlated to both LVEF and PFR (r = 0.64, p < 0.0001, and r = 0.36, p = 0.0037, respectively), whereas no correlation was found with pulmonary function impairment or pulmonary arterial pressure. Nicardipine resulted in a significant increase in RVEF (from 36.5% +/- 7.0 to 42.3% +/- 8.4, p < 0.001) whereas afterload indicated by mean arterial pressure did not differ significantly. CONCLUSION: Reduced RVEF appears to be a common feature in early SSc; it may be due to intrinsic myocardial involvement and is acutely improved by nicardipine.     

Effect of oral combination therapy with mexiletine and quinidine on left and right ventricular function

Combination therapy with mexiletine (MEX) and quinidine (Q) may be more efficacious than monotherapy with either drug in suppressing ventricular arrhythmias, but its effects on ventricular performance are not known. Thus, right ventricular ejection fraction (RVEF) and left ventricular ejection fraction (LVEF) and wall motion score (WMS) were assessed in 14 patients with ventricular tachycardia before antiarrhythmic therapy, during MEX and Q monotherapies, and during combination therapy. During monotherapy, the daily doses and serum drug levels were: MEX, 621 mg/day and 3.4 microM/L; Q, 1573 mg/day and 8.3 microM/L, respectively. With combination therapy, the daily doses and serum drug levels were: MEX, 636 mg/day and 3.3 microM/L; Q, 1643 mg/day and 9.5 microM/L, respectively. Drug therapy did not affect group LVEF (drug free = 36 +/- 19%, MEX = 34 +/- 18%, Q = 36 +/- 19%, and combination MEX-Q = 35 +/- 19%), RVEF (drug free = 34 +/- 11%, MEX = 35 +/- 11%, Q = 36 +/- 13%, and combination MEX-Q = 36 +/- 12%), or WMS. Ventricular function reserve was assessed in five patients. Drug therapy did not affect group exercise LVEF (drug free = 44 +/- 14%, MEX = 42 +/- 12%, Q = 43 +/- 13%, and MEX-Q = 45 +/- 12%), RVEF (drug free = 38 +/- 10%, MEX = 40 +/- 11%, Q = 39 +/- 12%, and MEX-Q = 40 +/- 12%), WMS, or exercise duration. Combination MEX-Q therapy did not have a significant effect on exercise performance or ventricular function in seven additional patients in whom no exercise studies were done during monotherapy.(ABSTRACT TRUNCATED AT 250 WORDS)     

Right ventricular function in valvular heart disease: relation to pulmonary artery pressure

Right ventricular angiography was performed in 46 patients with acquired valvular heart disease and 8 normal subjects. Right ventricular ejection fraction (RVEF) correlated highly only with right ventricular peak systolic pressure (RVPSP) and mean pulmonary artery pressure, both in patients with and without tricuspid insufficiency. For the group, RVEF = -0.33 RVPSP + 63 (correlation coefficient [r] = -0.76, probability [p] less than 0.001). Of 20 patients with moderate or severe elevation of pulmonary artery pressure, 17 (85%) had an abnormally low ejection fraction (less than 47%), while 19 (73%) of 26 patients with normal or mildly elevated pulmonary artery pressure had a normal right ventricular ejection fraction. In seven patients with elevated pulmonary artery pressure, a second ventriculogram was performed during intravenous nitroglycerin administration. Nitroglycerin produced a significant decrease in right ventricular peak systolic pressure (59 +/- 22 to 49 +/- 18 mm Hg, mean +/- standard deviation) (p less than 0.05) and in end-systolic volume (71 +/- 16 to 59 +/- 11 m1/m2) (p less than 0.05), and an increase in ejection fraction (43 +/- 9 to 48 +/- 7%) (p less than 0.05). Thus, at least part of the depression of ejection fraction in patients with elevated pulmonary pressure is reversible with a decrease in pulmonary artery pressure.     

Clinical response and effects on left ventricular function of isosorbide dinitrate added to propranolol or diltiazem monotherapy in patients with chronic stable angina

Twenty-four patients were randomized to a double-blind, triple placebo controlled, latin square protocol to examine the relative efficacy of propranolol or diltiazem given as monotherapy or in combination with isosorbide dinitrate. Treatment phases were preceded and followed by placebo control periods. At the end of each phase, symptom-limited treadmill exercise stress tests were performed, as well as rest and exercise radionuclide ventriculography. Both forms of monotherapy were effective in reducing episodes of angina and nitroglycerin use, and in improving exercise tolerance. Diltiazem monotherapy was associated with slightly higher treadmill times (509.9 +/- 123 s) compared to propranolol (462.7 +/- 131 s, P less than 0.05). The addition of isosorbide dinitrate to either form of monotherapy allowed no further improvement in any of the measured clinical responses. Radionuclide ventriculography showed no significant difference in resting left ventricular function. The addition of isosorbide dinitrate to propranolol showed a reduction in end diastolic volume in keeping with a reduction in preload. In response to exercise, stress-induced left ventricular dysfunction was equal in all groups except for the diltiazem-nitrate combination, which was associated with a higher ejection fraction (56.2 +/- 8.6%) compared to monotherapy (52.6 +/- 10.9%, P less than 0.01). A higher cardiac output could be achieved in the groups treated with diltiazem; this was related to increased heart rate and maintenance of stroke volume. It was concluded that diltiazem is equally effective as propranolol for the treatment of chronic stable angina and, in terms of exercise capacity and cardiac output, superior to beta-blockade. The addition of isosorbide dinitrate appears to impart no overt benefits, but some evidence suggests a reduction in left ventricular decompensation in the face of stress.     

Evaluation of right ventricular function in severe left ventricular failure: comparison of old myocardial infarction with dilated cardiomyopathy

To evaluate right ventricular (RV) function in severe left ventricular (LV) failure, we measured RV and LV ejection fractions (EF) in 18 patients with old myocardial infarction (OMI) and in 18 with dilated cardiomyopathy (DCM) using cardiac blood pool scintigraphy. In patients with OMI, RVEF was significantly greater in stage II LV failure than in stage III (functional class of the New York Heart Association, 47 +/- 8% and 28 +/- 12%, respectively: p less than 0.01), and this correlated well with exercise tolerance by bicycle ergometer and mean pulmonary artery pressure (r = 0.83 and r = -0.71, respectively). In patients with DCM, however, there was no correlation between RVEF and these indexes. After the oral administration of denopamine (beta 1 effector), both RVEF and LVEF increased in patients with OMI (35 +/- 13% to 45 +/- 12%, and 27 +/- 9% to 30 +/- 10%: p less than 0.01), but they did not change significantly in patients with DCM. These results indicate that RVEF in patients with OMI correlates well with subjective symptoms, exercise tolerance and RV afterload, but these correlations were not apparent in patients with DCM. We concluded that RV function in cases of severe LV failure has a different meaning between OMI and DCM.     

Improvement of right ventricular systolic performance by long-term domiciliary oxygen therapy in patients with chronic respiratory failure

Eight patients with clinically stable chronic respiratory failure, hypoxemia (PaO2 less than or equal to 60 mmHg) and pulmonary hypertension (mean pulmonary arterial pressure greater than or equal to 20 mmHg) were allocated to long-term domiciliary oxygen therapy, and were followed for three months. Oxygen was supplied for from 15 to 18 hours daily from an oxygen concentrator at a flow rate sufficient to raise the PaO2 to 60 to 80 mmHg. We examined the effects of this therapy on right ventricular performance both at rest and during exercise in these patients. Hemodynamic data were obtained by right heart catheterization. Right ventricular ejection fractions (RVEF) were ascertained using first-pass quantitative radionuclide 81mKr angiocardiography. Thirty minutes of oxygen inhalation at rest had no significant effect on cardiac function, both before therapy (T0) and after 3 months of therapy (T1). The mean pulmonary arterial pressure and the pulmonary vascular resistance during exercise were not significantly different between T0 and T1. On the other hand, at T0, the RVEF tended to decrease from 51.6 +/- 4.9% (during oxygen inhalation at rest) to 48.7 +/- 7.9% (during exercise), whereas at T1 it significantly (p less than 0.05) increased from 48.8 +/- 6.8% (during oxygen inhalation at rest) to 54.2 +/- 8.2% (during exercise). Thus, while 3 months of long-term domiciliary oxygen therapy did not reduce the right ventricular afterload either at rest or during exercise, it was found to improve the right ventricular systolic performance during exercise. This suggested that long-term oxygen therapy could be useful in improving the quality of daily life of patients with chronic respiratory failure.     

Normal right ventricular systolic and diastolic function assessed by krypton-81m equilibrium ventriculography

Krypton-81m equilibrium ventriculography was used to study right ventricular function in 23 healthy male volunteers. Technetium-99m lung perfusion scintigraphy was employed to subtract radionuclide activity within lung during image analysis thereby enhancing image quality. The imaging technique was used to generate a time-activity curve for the right ventricle allowing the definition of indices of normal systolic and diastolic function for the right ventricle. At rest, indices of systolic ejection and diastolic filling were comparable to those previously reported for the left ventricle. Using this imaging technique, movement artifact during exercise reduces image quality and limits accurate measurement of these indices to resting studies.Abbreviations RVEF right ventricular ejection fraction     

Equilibrium radionuclide right ventriculography at rest and during exercise in patients with pulmonary hypertension

Using the method of equilibrium radionuclide ventriculography (RNV), the right ventricular ejection fraction (RVEF) at rest and at a standard workload of 250 kpm per min was determined in 25 control subjects and in 30 patients with pulmonary hypertension (8 patients with chronic obstructive bronchopulmonary disease, 12 with recurrent pulmonary embolism and 10 with pure mitral stenosis). In the same week as RNV, pulmonary artery pressure was registered in patients with pulmonary hypertension at rest and at standard workload. RVEF was significantly higher (45 +/- 5%) in normal subjects than in patients with pulmonary hypertension (33 +/- 5%) and during exercise increased, whereas in patients with pulmonary hypertension it did not markedly change or decreased. The RVEF correlated at rest (r = -0.6293, p less than 0.001) and during exercise (r = 0.6980, p less than 0.05) with the degree of pulmonary hypertension at rest and during exercise. The results show a good correlation between the RVEF and the degree of pulmonary hypertension in patients with pulmonary hypertension at rest and during exercise.     

Function of the right ventricle in patients with mitral valve diseases

To investigate right ventricular function in mitral valve disease, biplane cineventriculograms of the right and left ventricle were performed in 96 patients-35 with mitral stenosis, 26 with mitral regurgitation, 12 with combined mitral valve disease, 14 with mitral stenosis and tricuspid regurgitation, and nine with mitral regurgitation and tricuspid regurgitation, compared to 18 normals (N). Right ventricular enddiastolic volume index was moderately elevated in patients with mitral stenosis and concomitant tricuspid regurgitation (111.6 +/- 35.3 ml/m2, no significance compared to N: 95.9 +/- 21.8 ml/m2) and with mitral regurgitation and tricuspid regurgitation (107.9 +/- 45.1 ml/m2, no significance compared to N). A reduced right ventricular ejection fraction (RVEF less than or equal to 50%) was found in 40 of the 96 patients. Right ventricular ejection fraction was frequently reduced in patients with mitral regurgitation and tricuspid regurgitation (46.7% +/- 15.1%) and significantly reduced in patients with combined mitral valve disease (45.0 +/- 17.6%, compared to N: 58.0 +/- 7.1%, p less than 0.01). No significant correlations were found between right ventricular ejection fraction and left ventricular enddiastolic volume or left ventricular ejection fraction in patients with mitral valve disease. Moreover, right ventricular ejection fraction did not correlate with systolic pulmonary artery pressure, mean pulmonary artery pressure or mean pulmonary capillary wedge pressure. Local wall motion (mean systolic shortening) was determined for the anterior, anteroapical, and inferior segment in the RAO-projection and for the right ventricular free wall in the LAO-projection. 63% of the patients (n = 25) with reduced right ventricular function (RVEF less than of equal to 50%) showed local wall motion abnormalities, preferably in the anterior segment of the RAO- projection (48%) and the right ventricular free wall (30%).(ABSTRACT TRUNCATED AT 250 WORDS)     

Right ventricular function in patients with chronic obstructive pulmonary disease measured by krypton-81m

Right ventricular function was assessed at rest and during exercise in patients with chronic obstructive pulmonary disease (COPD). Right ventricular ejection fraction (RVEF) was measured by first-pass radionuclide angiography using ultrashort-lived radionuclide krypton-81m. The half-life of this nuclide is only 13 sec, and it is completely expired from the lungs. These properties allow measurement of RVEF without correcting for background activity. In 30 patients with cardiac or pulmonary disease, RVEF was first measured by krypton-81 m scintigraphy (Kr-RVEF), then by technetium-99m (Tc-RVEF), without changing the patients' positions. In eight of the 30 cases, right ventricular cineangiography (RVG) was performed within 72 hrs after the radionuclide study, and RVEF was measured according to the Chapman's rule (RVG-RVEF). Kr-RVEF correlated significantly with Tc-RVEF (r = 0.87), and also with RVG-RVEF (r = 0.80). In 10 patients with stable COPD, who had severe hypoxemia (PaO2 less than or equal to 60 mmHg) and pulmonary hypertension [mean pulmonary arterial pressure (mean PAP) greater than or equal to 20 mmHg], and in seven normal control subjects, radionuclide angiographic and hemodynamic monitoring were performed at rest and during supine ergometer exercise. Kr-RVEF at rest was 47.6 +/- 5.4% (mean +/- SD) in patients with COPD and was 54.1 +/- 4.8% in normal subjects. Kr-RVEF during exercise was 51.8 +/- 7.3% in the patients, and 62.3 +/- 3.2% in the normal subjects. Hemodynamically, mean PAP and pulmonary vascular resistance (PVR) increased significantly during exercise, but the RV end-diastolic volume index (RVEDVI) did not change. There was inverse correlation between Kr-RVEF and mean PAP (r = -0.51) or PVR (r = -0.47) as an index of RV afterload. However, there was no correlation between Kr-RVEF and RVEDVI as an expression of RV preload. These findings suggest that a poor response by RVEF during exercise in patients with COPD is associated with elevation of afterload. Thus, right ventricular imaging techniques using the ultrashort-lived nuclide krypton-81 m allow noninvasive, serial and accurate assessments of right ventricular function in patients with COPD.     

Noninvasive diagnosis of pulmonary arterial hypertension in chronic obstructive pulmonary disease: right ventricular ejection fraction at rest

Because right ventricular ejection fraction (RVEF) depends on impedance to RV ejection, the hypothesis was tested that an abnormality in radionuclide-determined RVEF would be a useful noninvasive predictor of pulmonary artery (PA) hypertension in patients with chronic obstructive pulmonary disease (COPD). Simultaneous measurements of resting RVEF and PA pressure were made in 30 patients with COPD. All were stable and without clinical evidence of respiratory decompensation or congestive heart failure. Eleven patients had normal (less than 20 mm Hg) mean PA pressure and 19 patients had PA hypertension. The average RVEF was 41 +/- 7% (range 29 to 60%). Five patients had normal (greater than 45%) and 25 patients depressed RVEF. An inverse linear relation between mean PA pressure and RVEF was present (r = -0.74). In the group with normal PA pressure, RVEF averaged 48% (range 42 to 60%). In the group with PA hypertension, RVEF averaged 36% (range 29 to 44%). RVEF was significantly higher in the group with PA hypertension. Using RVEF less than 45% as an indicator of PA hypertension, the sensitivity was 100%, the specificity 55%, and the predictive accuracy of a positive result 79%. Using RVEF less than or equal to 40% as an indicator of PA hypertension, the sensitivity was 75%, the specificity 100%, and the predictive accuracy of a positive study 100%. Thus, radionuclide-determined RVEF using the first-pass technique and a multicrystal camera is a useful noninvasive test for diagnosing PA hypertension in patients with advanced COPD.     

Rest and exercise ventricular function in adults with congenital ventricular septal defects

Rest and exercise right and left ventricular function were compared using equilibrium gated radionuclide angiography in 19 normal sedentary control subjects (mean age 28 years, range 22 to 34) and 34 patients with hemodynamically documented congenital ventricular septal defect (VSD) (mean age 27 years, range 20 to 40). The 34 patients with VSD were divided into 3 groups: those in Group 1 (17 patients) had pulmonary to systemic blood flow ratios of less than 2 to 1; those in Group 2 (12 patients) had prior surgical closure of VSD (mean interval from surgery 17 years, range 9 to 22), and those in Group 3 (5 patients) had Eisenmenger's complex. Gated radionuclide angiography was performed at rest and during each level of graded supine bicycle exercise to fatigue. Heart rate, blood pressure, maximal work load achieved, and right and left ventricular ejection fractions were assessed. The control subjects demonstrated an increase in both the left and right ventricular ejection fractions with exercise (0.70 +/- 0.07 to 0.79 +/- 0.05 and 0.46 +/- 0.06 to 0.57 +/- 0.04; p less than 0.001 for left and right ventricles, respectively). All study groups failed to demonstrate an increase in ejection fraction in either ventricle with exercise. Furthermore, resting left ventricular ejection fraction in Groups 2 and 3 was lower than that in the control subjects (0.59 +/- 0.09 and 0.54 +/- 0.06 versus 0.70 +/- 0.07; p less than 0.001) and resting right ventricular ejection fraction was lower in Group 3 versus control subjects (0.30 +/- 0.07 versus 0.46 +/- 0.06; p less than 0.001). Thus (1) left and right ventricular function on exercise were abnormal in patients with residual VSD as compared with control subjects; (2) rest and exercise left ventricular ejection fractions remained abnormal despite surgical closure of VSD in the remote past; (3) resting left and right ventricular function was abnormal in patients with Eisenmenger's complex; (4) lifelong volume overload may be detrimental to myocardial function.     

Effects of oral mexiletine on left and right ventricular function

Malignant ventricular arrhythmias often occur in patients with left ventricular (LV) dysfunction. Antiarrhythmic drugs may further impair LV function in these patients. Mexiletine, a lidocaine congener, is an effective antiarrhythmic drug, but when administered orally, its effect on LV and right ventricular (RV) function is unknown. To determine the hemodynamic effects of mexiletine, LV and RV ejection fraction (EF) were measured by radionuclide ventriculography in 10 patients with LV dysfunction (LVEF less than 50%). Symptom-limited exercise tests were also performed. Patients were studied before and during therapy with oral mexiletine. There was no significant change in LVEF (28% vs 27%) or RVEF (46% vs 41%). Also, heart rate at rest, exercise duration and peak heart rate during exercise were unchanged. Thus, in patients with LV dysfunction, oral mexiletine does not significantly affect LV or RV function.