Isovolumic relaxation period in hypertrophic cardiomyopathy: assessment by radionuclide angiography

Left ventricular isovolumic relaxation and the relation between relaxation and filling were studied in 90 patients with hypertrophic cardiomyopathy and 29 control subjects using radionuclide angiography. The isovolumic relaxation period was determined automatically on left ventricular time-activity curves as the interval between minimal volume and onset of rapid filling. In 17 patients, M-mode echocardiography performed simultaneously with radionuclide angiography demonstrated that onset of mitral valve opening correlated well with onset of rapid filling (r = 0.84, p less than 0.001). The isovolumic relaxation period was longer in patients with hypertrophic cardiomyopathy than in control subjects (95 +/- 44 versus 50 +/- 23 ms, p less than 0.01) and was longer in patients without an outflow tract gradient at rest than in patients with a gradient (109 +/- 37 versus 86 +/- 35 ms, p less than 0.05). In these patients without obstruction, a weak linear relation between duration of the isovolumic period and peak filling rate was found (r = 0.48, p less than 0.02). Filling was impaired in patients with hypertrophic cardiomyopathy, as assessed by lower peak filling rate (3.2 +/- 1.2 versus 3.5 +/- 0.5 end-diastolic volume/s, p less than 0.05) and prolonged time to peak filling rate (185 +/- 44 versus 145 +/- 20 ms, p less than 0.01) compared with values in control subjects. The delay in time to peak filling rate was caused primarily by the prolonged isovolumic period, because the interval from onset of rapid filling to peak filling rate was similar in patients with hypertrophic cardiomyopathy and control subjects (87 +/- 31 versus 95 +/- 25 ms, NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Indications for coronary artery bypass surgery in patients with chronic angina pectoris: implications of the multicenter randomized trials

The three major randomized studies of medical vs surgical therapy in patients with coronary artery disease have had a major impact in the management of patients with this disease. For the most part, these multicenter trials have provided concordant information regarding the influence of surgery on survival in asymptomatic or mildly symptomatic patients. It has been demonstrated that coronary artery bypass surgery improves survival in patients with stenosis of the left main coronary artery. Bypass surgery probably should be performed in most patients with this lesion, although studies have identified low-risk subgroups in whom surgery may not improve survival. There are also concordant data that survival is not enhanced by surgery in mildly symptomatic patients with either one- or two-vessel disease. The important discrepancies regarding the role of surgery in three-vessel disease have been resolved to a major extent. Long-term follow-up studies in the Veterans Administration Cooperative Study and the Coronary Artery Surgery Study (CASS) demonstrate improved survival with surgical management in patients with three-vessel disease and left ventricular dysfunction. The remaining controversy regards management of patients with three-vessel disease and normal left ventricular function; this may be resolved by studies indicating that inducible left ventricular ischemia in patients with three-vessel disease and preserved left ventricular function at rest identifies patients at higher risk during medical management. Different proportions of such patients entered into the multicenter studies may explain the discordant results in three-vessel disease and normal left ventricular function reported by the European trial and CASS.(ABSTRACT TRUNCATED AT 250 WORDS)

Survival and functional results after valve replacement for aortic regurgitation from 1976 to 1983: impact of preoperative left ventricular function

Recent studies suggest that preoperative left ventricular function may no longer be an important determinant of survival or functional results after operation for aortic regurgitation because of improved operative techniques. To assess the effect of left ventricular function on prognosis in the current surgical era, we performed echocardiographic and radionuclide angiographic studies in 80 consecutive patients undergoing valve replacement from 1976 to 1983. No patient had associated coronary artery disease. For all patients, 5 year survival was 83 +/- 5%, significantly better than the 62 +/- 9% 5 year survival in our patients operated on from 1972 to 1976. Preoperative resting left ventricular ejection fraction (p less than .001), fractional shortening (p less than .001), and end-systolic dimension (p less than .01) were the most significant predictors of survival (univariate life-table analysis). Five year survival was 63 +/- 12% in patients with subnormal ejection fraction (n = 50) compared with 96 +/- 3% in those with normal ejection fraction (n = 30). Patients with subnormal left ventricular ejection fraction and poor exercise tolerance or prolonged duration of left ventricular dysfunction (greater than 18 months) comprised the high-risk subgroup (5 year survival 52 +/- 11%). Patients in this subgroup also had persistent left ventricular dysfunction after operation, with greater left ventricular end-diastolic dimensions and reduced ejection fraction (both p less than .001) compared with patients with normal preoperative left ventricular ejection fraction or a brief duration of left ventricular dysfunction (less than 14 months). Cold hyperkalemic cardioplegia was used for myocardial preservation in 46 patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of sublingual nifedipine on hemodynamics and systolic and diastolic function in patients with hypertrophic cardiomyopathy

The hemodynamic effects of sublingual nifedipine were examined in 36 patients with hypertrophic cardiomyopathy. Twenty-one patients were initially given 20 mg and 15 patients were given 10 mg of the drug; 30 min after this first dose 26 patients received 10 mg and one patient 20 mg as a second dose. Hemodynamic findings in patients who received different doses of the drug were similar. Peak effects included an increase in heart rate from 79 +/- 12 to 91 +/- 14 (mean +/- 1 SD) beats/min (p less than .01), and a decrease in mean blood pressure from 89 +/- 12 to 77 +/- 10 mm Hg (p less than .01). Cardiac index increased after nifedipine (2.8 +/- 0.6 to 3.3 +/- 0.8 liters/min/m2; p less than .01); stroke volume index, however, did not change (36 +/- 7 to 36 +/- 8 ml/beat/m2; NS). Peripheral vascular resistance index fell significantly from 822 +/- 261 to 610 +/- 197 dynes X sec X cm-5 (p less than .01). Overall, left ventricular outflow tract gradient (LVOTG) did not change in patients with significant (greater than or equal to 30 mm Hg) basal LVOTG (75 +/- 22 to 83 +/- 22 mm Hg; NS), but it increased significantly in those six patients in whom peripheral vascular resistance fell by 25% or more (73 +/- 28 to 99 +/- 22 mm Hg; p less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)

Verapamil-induced improvement in left ventricular diastolic filling and increased exercise tolerance in patients with hypertrophic cardiomyopathy: short- and long-term effects

Verapamil improves exercise tolerance and decreases symptoms in many patients with hypertrophic cardiomyopathy. The mechanisms responsible for these effects are not completely understood, although previous studies indicate that verapamil enhances left ventricular relaxation and diastolic filling in such patients. To investigate the association between changes in left ventricular filling and exercise tolerance after verapamil, we studied 55 patients with hypertrophic cardiomyopathy by radionuclide angiography and graded treadmill testing before and after 1 to 4 weeks of therapy with orally administered verapamil, 320 to 640 mg/d. The verapamil-induced increase in peak left ventricular filling rate at rest (from 3.1 +/- 1.3 to 3.7 +/- 1.3 end-diastolic volumes/sec; p less than .001) was associated with an increase in exercise tolerance (from 5.9 +/- 3.6 to 8.7 +/- 4.7 min; p less than .001); exercise capacity increased in 34 of 43 patients (79%) manifesting an increase in peak filling rate but only one of 12 patients (8%) with unchanged or decreased peak filling rate (p less than .001). This initial trend persisted in 25 patients studied after 1 year of therapy; 11 of 16 patients (69%) with a persistent increase in peak filling rate had persistent improvement in exercise tolerance relative to preverapamil values, compared with only one of nine patients (11%) in whom peak filling rate was unchanged or decreased relative to preverapamil levels (p less than .02). Verapamil withdrawal after 1 to 2 years in 24 patients resulted in reduction in peak filling rate (p less than .001) and was associated with deterioration in exercise tolerance in 17 patients (71%). Hence, verapamil-induced changes in left ventricular peak filling rate were associated significantly with objective symptomatic improvement. These data support the concept that enhanced left ventricular diastolic filling is an important mechanism contributing to the clinical improvement experienced by many patients with hypertrophic cardiomyopathy during therapy with verapamil.

Myocardial ischemia in patients with hypertrophic cardiomyopathy: contribution of inadequate vasodilator reserve and elevated left ventricular filling pressures

To study the mechanism and hemodynamic significance of myocardial ischemia in hypertrophic cardiomyopathy, 20 patients (nine with resting left ventricular outflow tract obstruction greater than or equal to 30 mm Hg) with a history of angina pectoris and angiographically normal coronary arteries underwent a pacing study with measurement of great cardiac vein flow, lactate and oxygen content, and left ventricular filling pressure. Compared with 28 control subjects without hypertrophic cardiomyopathy, their resting coronary blood flow was higher (91 +/- 27 vs 66 +/- 17 ml/min; p less than .001) and their coronary resistance was lower (1.13 +/- 0.38 vs 1.55 +/- 0.45 mm Hg/ml/min; p less than .001). Left ventricular end-diastolic pressure (16 +/- 6 vs 11 +/- 3 mm Hg; p less than .001) and pulmonary arterial wedge pressure (13 +/- 5 vs 7 +/- 3 mm Hg; p less than .001) were significantly higher in patients with hypertrophic cardiomyopathy. During pacing, coronary flow rose in both groups, although coronary and myocardial hemodynamics differed greatly. In contrast to the linear increase in flow in control subjects up to heart rate of 150 beats/min (66 +/- 17 to 125 +/- 28 ml/min), patients with hypertrophic cardiomyopathy demonstrated an initial rise in flow to 133 +/- 31 ml/min at an intermediate heart rate of 130 beats/min. At this point, 12 of 20 patients developed their typical chest pain. With continued pacing to a heart rate of 150 beats/min, mean coronary flow fell to 114 +/- 29 ml/min (p less than .002), with 18 of 20 patients experiencing their typical chest pain and metabolic evidence of myocardial ischemia. This fall in coronary flow was associated with a substantial rise in left ventricular end-diastolic pressure (30 +/- 9 mm Hg immediately after peak pacing). In the 14 patients whose coronary flow actually fell from intermediate to peak pacing, the rise in left ventricular end-diastolic pressure in the same interval was greater than that of the six patients whose flow remained unchanged or increased (11 +/- 8 vs 2 +/- 2 mm Hg; p less than .01). In addition, despite metabolic and hemodynamic evidence of myocardial ischemia, the arteriovenous O2 difference actually narrowed at peak pacing. Thus most patients with hypertrophic cardiomyopathy achieved maximum coronary vasodilation and flow at modest increases in heart rate. Elevation in left ventricular filling pressure, probably related to ischemia-induced changes in ventricular compliance, was associated with a decline in coronary flow.(ABSTRACT TRUNCATED AT 400 WORDS)

Asynchronous left ventricular regional function and impaired global diastolic filling in patients with coronary artery disease: reversal after coronary angioplasty

Left ventricular diastolic filling is impaired in many patients with coronary artery disease and normal left ventricular systolic function, and is improved in many patients after coronary angioplasty (PTCA). To investigate the mechanisms for this improvement, we studied regional asynchrony by radionuclide angiography in 26 patients with single-vessel coronary artery disease before and after successful PTCA. Before PTCA, all patients had normal ejection fractions at rest and normal qualitative left ventricular regional wall motion, as determined by radionuclide and contrast angiography. Quantitative left ventricular regional function was assessed by dividing the left ventricular region of interest into 20 sectors. Phase analysis was performed on each sector's time-activity curve, and the average intersector phase difference was used as an index of left ventricular regional synchrony. Before PTCA, average intersector phase difference was increased compared with normal (6.0 +/- 2.2 vs 4.0 +/- 1.7 degrees, p less than .005), indicating asynchronous regional function. After PTCA, ejection fraction at rest was unchanged, but peak left ventricular filling rate at rest increased from 2.5 +/- 0.6 to 3.0 +/- 0.6 end-diastolic volume/sec (p less than .001) and was associated with a decrease in average intersector phase difference from 6.0 +/- 2.2 to 5.1 +/- 2.3 degrees (p less than .05). Average intersector phase difference decreased in 16 of 21 patients in whom peak filling rate increased after PTCA (p less than .005), compared with one of five patients in whom peak filling rate was unchanged or decreased. Hence, improved global left ventricular filling after PTCA was associated with more synchronous left ventricular regional behavior. To identify the cause of regional asynchrony before PTCA, we then generated time-activity curves from each of four left ventricular quadrants. These data indicated that the asynchrony was caused by regional variation in timing of diastolic rather than systolic events and that PTCA resulted in reduction in regional diastolic asynchrony. These data suggest that in many patients with coronary artery disease and normal left ventricular systolic function, impaired global diastolic filling may result from asynchronous left ventricular regional diastolic function, which is a reversible manifestation of myocardial ischemia or reduced coronary flow.

Left ventricular dysfunction in patients with angina pectoris, normal epicardial coronary arteries, and abnormal vasodilator reserve

Thirty-three patients with chest pain despite angiographically normal coronary arteries underwent both coronary flow studies during pacing and resting and exercise gated blood pool scintigraphy. During atrial pacing after administration of ergonovine, those patients developing their typical chest pain demonstrated significantly lower great cardiac vein flow (97 +/- 31 vs 150 +/- 33 ml/min, p less than .001), higher coronary resistance (1.27 +/- 0.43 vs 0.77 +/- 0.18 mm Hg/ml/min, p less than .005), and less lactate consumption (30.5 +/- 22.0 vs 69.7 +/- 41.1 mM . ml/min, p less than .005) and a higher left ventricular end-diastolic pressure after pacing (20 +/- 4 vs 12 +/- 1, p less than .001) compared with those without pain and in the absence of significant luminal narrowing of the epicardial coronary arteries. The 26 patients with abnormal vasodilator reserve demonstrated reduced left ventricular ejection fraction during exercise (58 +/- 8%) compared with the seven patients with appropriate vasodilator reserve (66 +/- 4%, p less than .05) and with a group of 52 control patients of similar age and sex distribution and free of known heart disease (66 +/- 10%, p less than .001). In addition, 12 of the 26 patients with abnormal vasodilator reserve demonstrated exercise-induced regional wall motion abnormalities. Many of these patients also manifested impaired left ventricular diastolic filling at rest compared with the control subjects (peak filling rate 2.6 +/- 0.7 vs 3.2 +/- 0.7 end-diastolic volume/sec, p less than .005). Thus, patients with chest pain resulting from abnormal vasodilator reserve demonstrate abnormalities of left ventricular systolic and diastolic function suggestive of myocardial ischemia.

Use of calcium-channel blocking drugs in hypertrophic cardiomyopathy

Verapamil exerts a wide spectrum of hemodynamic effects in patients with hypertrophic cardiomyopathy (HC), and its administration offers an important alternative to beta-receptor blocker therapy in such patients. The intravenous administration of verapamil to 62 patients in the catheterization laboratory decreased systolic blood pressure from 118 +/- 17 to 102 +/- 17 mm Hg (p less than 0.001). It had no significant effect on heart rate, mean pulmonary artery wedge pressure, left ventricular (LV) end-diastolic pressure or cardiac output; however, LV outflow gradient in the basal state decreased from 62 +/- 34 to 29 +/- 34 mm Hg (p less than 0.05). These findings demonstrate a decrease in LV outflow tract obstruction. Radionuclide angiography indicated the major action responsible for the reduction in obstruction appears to be an improvement in LV diastolic function. Short-term nifedipine administration to patients with HC produced no significant effect on LV outflow tract gradients and early diastolic filling. Short-term double-blind studies showed that verapamil improved exercise time by 26 +/- 35% (p less than 0.005) compared with placebo, whereas propranolol improved it by 21 +/- 35% (p less than 0.025). In a separate study, verapamil improved exercise duration by 38 +/- 58% (p = 0.02) compared with placebo, whereas nifedipine improved it by 20 +/- 47% (difference is not significant). Verapamil resulted in a more beneficial subjective symptomatic response than propranolol or nifedipine when compared with placebo. Long-term verapamil therapy was instituted in 227 patients; 133 of these patients have continued taking the medication for an average of 25 +/- 13 months because their quality of life improved compared with what they experienced with their former therapy (usually beta blocker). Improved exercise capacity of 40% has been maintained in 32 patients for 2 years. A decrease in ventricular septal thickness of 1.5 +/- 2.6 mm was also found in 32 patients studied after 39 +/- 8 months of verapamil therapy. Nine patients died during follow-up study, but it is unclear whether the drug increased survival or, conversely, whether any of the deaths could be attributed to verapamil administration. Significant adverse electrophysiologic and hemodynamic effects were seen in 59 instances. The electrophysiologic events, atrioventricular block and sinus arrest, were definitely verapamil-related, but it is uncertain how many of the hemodynamic problems of hypotension and pulmonary congestion were drug-related.(ABSTRACT TRUNCATED AT 400 WORDS)

Effects of calcium-channel blocking agents on left ventricular diastolic function in hypertrophic cardiomyopathy and in coronary artery disease

Abnormal left ventricular (LV) diastolic performance is a characteristic feature of hypertrophic cardiomyopathy (HC) and an important contributor to the development of symptoms. Impaired diastolic filling of the hypertrophied left ventricle results from both diminished distensibility and prolonged or incomplete relaxation. LV distensibility is not only influenced by fixed anatomic abnormalities (such as fibrosis or hypertrophy) that determine the passive elastic properties of the left ventricle, but also is modulated by the dynamics of myocardial relaxation: prolonged or incomplete LV relaxation may restrict the rate and extent of LV filling and result in altered pressure-volume relations throughout diastole. Several studies indicate that impaired LV relaxation and filling in HC may be modified favorably by verapamil or nifedipine administered on a short-term basis in the catheterization laboratory, associated with improved diastolic pressure-volume relations. Verapamil also improves LV filling during oral therapy. Improved indexes of LV filling correlate with symptomatic improvement, both short-term and long-term: Approximately 80% of patients having a persistent increase in peak LV filling rate have persistent improvement in objective exercise tolerance compared with preverapamil values. Altered LV relaxation and filling are also often observed in patients with coronary artery disease (CAD) after myocardial infarction or during acute ischemia. Moreover, impaired filling occurs under resting conditions in many patients who have normal systolic function and no evidence of previous infarction. Nifedipine improves indexes of LV relaxation and distensibility during pacing-induced ischemia and verapamil improves indexes of LV filling at rest and during exercise-induced ischemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Dynamic coronary obstruction as a cause of angina pectoris: implications regarding therapy

The strong link demonstrated at autopsy between coronary atherosclerosis and angina pectoris led to the important concept that a fixed obstruction of 1 or more coronary arteries was the pathophysiologic cause of angina: myocardial ischemia and angina occurred when myocardial oxygen demand out-stripped the capacity of the diseased coronary artery to deliver oxygen. Therapeutic strategies were based on attempts to lower myocardial oxygen needs induced by physical and emotional stress. However, the finding that dynamic increases in coronary vascular resistance can also either precipitate ischemia or reduce the threshold of myocardial oxygen consumption (MVO2) at which it occurs has profoundly altered our understanding of the pathophysiologic features of angina and, therefore, its treatment. Dynamic coronary obstruction can occur at the large-vessel level, causing Prinzmetal's or variant angina. It is also possible that in some patients a continuum of large-vessel coronary vasoconstrictor tone exists, causing the common clinical situation manifested by angina with variable thresholds of onset. Recent studies have demonstrated that increases in the resistance offered to flow by small coronary arteries too small to be imaged by angiography can also decrease anginal threshold. The fact that ischemia can be precipitated by dynamic increases in large- or small-vessel coronary resistance has important implications for the therapy of angina pectoris. In those persons who mostly have a dynamic component contributing to their coronary obstruction, primary intervention with vasodilator therapy, including nitrates and calcium-channel blocking agents, are probably most effective therapeutically.(ABSTRACT TRUNCATED AT 250 WORDS)

Combination therapy with calcium-channel blockers and beta blockers for chronic stable angina pectoris

Combination therapy using calcium-channel blockers and beta blockers in patients with refractory chronic stable angina has gained much popularity, but remains highly controversial because of the potential for serious additive deleterious hemodynamic or electrophysiologic reactions. In studies involving patients with preserved left ventricular function receiving chronic oral beta blockers, short-term administration of intravenous verapamil has been shown to cause a further lowering in heart rate and blood pressure while prolonging atrioventricular node conduction; additive cardiodepressant effects were noted, including a tendency toward increased left and right heart filling pressures. Nifedipine, on the other hand, when added acutely to beta blockers, causes an increase in heart rate, a decrease in blood pressure and either no change or a slight improvement in most cardiac performance variables. Controlled, double-blind clinical trials have demonstrated that combinations of calcium-channel blockers and beta blockers result in augmented symptom benefit compared with either drug class alone. The predominant mechanism responsible for such improvement is increased lowering of myocardial oxygen demand by virtue of additive diminution in heart rate, blood pressure and, consequently, pressure-rate product both at rest and during exercise. Verapamil (and possibly diltiazem) plus beta blockers appears to have the greatest therapeutic efficacy but also the highest frequency of harmful adverse cardiac effects, whereas nifedipine plus beta blockers is generally safer but also less efficacious. Factors that should be carefully considered by clinicians contemplating combination therapy are the choice of calcium-channel blocker, the dose of calcium-channel blocker and beta blocker, the presence of antecedent left ventricular dysfunction or conduction system disease and the possibility of drug interactions. Concomitant calcium-channel blocker and beta-blocker therapy is an important contribution to the pharmacologic management of resistant patients who remain symptomatic during single drug treatment. However, the possibility of additive adverse cardiac effects mandates careful patient selection and close clinical monitoring.

Timing of operation for chronic aortic regurgitation: influence of left ventricular function on clinical management

Since symptomatic patients with aortic regurgitation and normal ventricular function (ejection fraction greater than or equal to 50%, fractional shortening greater than or equal to 29%, end-systolic diameter less than or equal to 55 mm) have a significantly higher three year survival postoperatively than patients with impaired left ventricular function (ejection fraction less than 50%, fractional shortening less than 29%, end-systolic diameter greater than 55 mm), the indication for surgery should be established prior to the onset of left ventricular functional impairment. In two-thirds or more of asymptomatic patients with left ventricular dysfunction, symptoms are incurred within two to three years. Additionally, in patients with impaired left ventricular function but with only slight or no symptoms or a normal exercise capacity, respectively, postoperatively there is a higher three year survival rate than in patients with marked symptoms or compromised exercise capacity. In patients in whom preoperative left ventricular dysfunction is present for only a relatively short duration (less than 14 months), the probability of postoperative regression of ventricular dilation and dysfunction is higher than in those whose left ventricular functional impairment is of longer duration (greater than 18 months). Thus, in asymptomatic patients with left ventricular dysfunction, the indication for surgery should be established before the onset of symptoms or compromise of exercise capacity. In asymptomatic patients with normal left ventricular function, symptoms or left ventricular dysfunction develop at a low incidence of 4% per year. Accordingly, with conservative, nonsurgical management, these patients have an excellent prognosis. Patients in whom the onset of symptoms or left ventricular dysfunction can be anticipated to develop, may be identified on the basis of an end-systolic diameter greater than 50 mm, a decrease in left ventricular ejection fraction during exercise, a progressive increase in the end-systolic as well as end-diastolic diameter or a rapid decrease in fractional shortening or ejection fraction seen during follow-up observation. The indication for surgery, however, should be established only at the onset of symptoms or left ventricular dysfunction since in all of these patients, regression of ventricular dilatation and normalization of left ventricular function can be expected postoperatively. The preoperative left ventricular function is a primary determinant of postoperative results even on employment of myocardial protection and a hemodynamically-favorable prosthesis.(ABSTRACT TRUNCATED AT 400 WORDS)

Exercise-induced ischemia in mildly symptomatic patients with coronary-artery disease and preserved left ventricular function. Identification of subgroups at risk of death during medical therapy

To determine prospectively whether the severity of reversible left ventricular ischemia provides prognostic information in mildly symptomatic patients with coronary-artery disease and preserved left ventricular function at rest (ejection fraction greater than 40 per cent), we studied 117 patients by means of exercise electrocardiography and radionuclide angiography. No patient had stenosis of the left main coronary artery. Mortality during subsequent medical therapy was significantly associated (by univariate life-table analysis) with three-vessel coronary-artery disease and the magnitude of the ejection fraction during exercise. In patients with three-vessel disease who had both ST-segment depression of 1 mm or more and a decrease in ejection fraction during exercise, in association with an exercise tolerance of 120 W or less, the probability of survival at four years was only 71 +/- 11 per cent (S.E.). All deaths occurred in this subgroup. Thus, objective evidence of left ventricular ischemia during exercise and exercise capacity identify one subgroup of minimally symptomatic patients with three-vessel disease with an excellent prognosis and another subgroup at relatively high risk of dying during subsequent medical therapy.

Reversal of left ventricular dysfunction after aortic valve replacement for chronic aortic regurgitation: influence of duration of preoperative left ventricular dysfunction

Preoperative left ventricular systolic function is an important predictor of postoperative prognosis in patients with aortic regurgitation. Although left ventricular dysfunction is reversible after aortic valve replacement to a greater extent in patients with good preoperative exercise capacity compared with patients with impaired exercise capacity, not all patients with preserved exercise capacity demonstrate improved left ventricular function after aortic valve replacement. To determine the influence of duration of preoperative left ventricular dysfunction on postoperative reversal of left ventricular dysfunction, we studied 37 patients with aortic regurgitation who preoperatively had left ventricular dysfunction, defined as subnormal echocardiographic fractional shortening (less than 29%), and good preoperative exercise capacity, defined as completion of stage I of the NIH treadmill protocol without limiting symptoms. Eight patients were asymptomatic. In 11 patients left ventricular dysfunction was documented 18 to 57 months preoperatively (prolonged); in 10 patients left ventricular dysfunction developed in an interval of 14 months or less preoperatively (brief); in 16 patients duration of left ventricular dysfunction was unknown. Patients with brief vs those with prolonged left ventricular dysfunction did not differ with respect to severity of preoperative symptoms or exercise tolerance, echocardiographically determined left ventricular dimensions or fractional shortening (25 +/- 3% [SD] vs 25 +/- 3%), or radionuclide angiographic ejection fraction (42 +/- 5% vs 42 +/- 5%).(ABSTRACT TRUNCATED AT 250 WORDS)

Exercise, electrocardiographic and functional responses after percutaneous transluminal coronary angioplasty

Exercise testing after successful PTCA showed improved cardiac functional status on examination of electrocardiographic and symptomatic responses, myocardial perfusion and global and regional left ventricular function. Sixty-six patients were studied before and after persistently successful PTCA. Follow-up studies an average of 8 months after the successful procedure showed an incidence of abnormal testing of only 7% using both electrocardiographic and subjective symptomatic criteria during treadmill studies and no abnormal studies with thallium scintigraphy. Radionuclide cineangiography demonstrated similar left ventricular ejection fractions at rest before and after PTCA, but an improvement of 9 +/- 10% (p less than 0.001) in the exercise ejection fraction at follow-up. However, 52% of patients with paired data still had an abnormal radionuclide cineangiographic study after successful PTCA, raising the question of the presence of subclinical ischemia or a false-positive result.

Relation between marked changes in left ventricular outflow tract gradient and disease progression in hypertrophic cardiomyopathy

Spontaneous and persistent changes in left ventricular (LV) outflow gradient have been observed occasionally in patients with hypertrophic cardiomyopathy (HC). However, the significance and frequency of such hemodynamic alterations have not been established. In this study, the serial preoperative hemodynamic status of 409 patients with HC was analyzed. Basal LV outflow tract obstruction either spontaneously appeared (or increased) or disappeared (or decreased) in 19 nonoperated patients (about 5%). Changes in hemodynamic state were shown by serial cardiac catheterization in 17 patients and by catheterization and M-mode echocardiography in 2 patients. In most patients (12 of 19), subaortic obstruction under basal conditions appeared or increased; 8 became more symptomatic and in 4 the condition remained stable. Reduction or loss of LV outflow gradient occurred in 7 patients; in 5 of these the condition deteriorated clinically and in 2 it did not change. Hence, in 13 of the 19 patients (70%), spontaneous changes in the magnitude of the basal LV outflow gradient were associated with symptomatic progression. The mechanism of the decrease or disappearance of subaortic obstruction in those patients who deteriorated clinically appeared to be related in 4 patients to impaired global and/or segmental LV function. Chronic atrial fibrillation probably contributed to the worsening clinical condition in 2 of these patients as well as in 2 others. In conclusion, substantial changes in the magnitude of basal subaortic obstruction may occur in a small proportion of patients with HC as part of the natural history of their disease, and such hemodynamic alterations are usually associated with clinical deterioration. It is exceedingly rare for the hemodynamic state of a patient with HC to change from totally nonobstructive to obstructive or vice versa, because such patients usually retain the capacity to generate gradients with provocative maneuvers.

Optimum fourier filtering of cardiac data: a minimum-error method: concise communication

Random fluctuations limit the accuracy of quantities derived from cardiac time-activity curves (TACs). To overcome this problem, TACs are often fitted with a truncated Fourier series giving rise to two sources of error: (a) the truncated series may not adequately describe the TAC shape, causing errors in parameters calculated from the fit: and (b) successive TACs acquired from the same subject under identical circumstances will fluctuate due to limited counts, causing the Fourier fits (and parameters derived from them) to fluctuate. These two errors, respectively, decrease and increase as the number of harmonics increases, suggesting the existence of a minimum in total error. This number of harmonics for minimum error (NHME) was calculated for each of six common parameters used to describe LV TACs. The "true" value of each parameter was determined from TACs of very high statistical precision. Poisson noise was added to simulate lower count rates. For low-count TACs, use of either a smaller or a larger number of harmonics resulted in significantly greater error. NHME was found to occur at two harmonics for the systolic parameters studied, regardless of the noise level present in the TAC. For diastolic parameters, however, NHME was a strong function of the noise present in the TAC, varying from three harmonics for noise levels typical of regional TACs, to five or six harmonics for high-count global TACs.

The acute and chronic effects of verapamil on left ventricular function in patients with hypertrophic cardiomyopathy

Verapamil therapy improves exercise tolerance and decreases symptoms in many patients with both obstructive and nonobstructive forms of hypertrophic cardiomyopathy. These salutory clinical effects result from favorable modification by verapamil of the pathophysiologic abnormalities in left ventricular function characteristic of this disease: impaired early diastolic relaxation and filling, reduced end-diastolic volume and stroke volume, hypercontractile systolic function, and, in many patients, subvalvular outflow tract obstruction. The acute administration of intravenous verapamil produces both significant negative inotropic effects and significant effects on left ventricular diastolic function, resulting in reduced contractile state, diminished outflow gradient, increased end-diastolic volume and stroke volume and improved relaxation and diastolic filling. In some patients, one effect may predominate over the other, and improved diastolic function may be masked by the profound changes in systolic function. During short-term oral therapy, enhanced diastolic function is the predominant effect, although negative inotropic mechanisms are evident in some patients. These effects on left ventricular systolic and diastolic function persist during chronic oral verapamil therapy, contributing to the long-term clinical improvement experienced by many patients.

Effects of verapamil on left ventricular systolic and diastolic function in patients with hypertrophic cardiomyopathy: pressure-volume analysis with a nonimaging scintillation probe

To investigate the effects of verapamil on left ventricular systolic and diastolic function in patients with hypertrophic cardiomyopathy, we studied 14 patients at catheterization with a nonimaging scintillation probe before and after serial intravenous infusions of low-, medium-, and high-dose verapamil (total dose 0.17 to 0.72 mg/kg). Percent change in radionuclide stroke counts after verapamil correlated well with percent change in thermodilution stroke volume (r = .87), and changes in diastolic and systolic counts were used to assess relative changes in left ventricular volumes after verapamil. Verapamil produced dose-related increases in end-diastolic counts (19 +/- 9% increase; p less than .001), end-systolic counts (91 +/- 54% increase; p less than .001), and stroke counts (7 +/- 10% increase; p less than .02). This was associated with a decrease in ejection fraction (83 +/- 8% control, 73 +/- 10% verapamil; p less than .001) and, in the 10 patients with left ventricular outflow tract gradients, a reduction in gradient (62 +/- 27 mm Hg control, 32 +/- 35 mm Hg verapamil; p less than .01). The end-systolic pressure-volume relation was shifted downward and rightward in all patients, suggesting a negative inotropic effect. In 10 patients, left ventricular pressure-volume loops were constructed with simultaneous micromanometer pressure recordings and the radionuclide time-activity curve. In five patients, verapamil shifted the diastolic pressure-volume curve downward and rightward, demonstrating improved pressure-volume relations despite the negative inotropic effect, and also increased the peak rate of rapid diastolic filling. In the other five patients, the diastolic pressure-volume relation was unaltered by verapamil, and increased end-diastolic volumes occurred at higher end-diastolic pressures; in these patients, the peak rate of left ventricular diastolic filling was not changed by verapamil. The negative inotropic effects of intravenous verapamil are potentially beneficial in patients with hypertrophic cardiomyopathy by decreasing left ventricular contractile function and increasing left ventricular volume. Verapamil also enhances left ventricular diastolic filling and improves diastolic pressure-volume relations in some patients despite its negative inotropic effect.