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PubMed2003

Stress echocardiography using transesophageal atrial pacing in rats.

BACKGROUND: Echocardiography is increasingly used for noninvasive evaluation of cardiac function and morphology in small animal models of cardiovascular diseases. The aims of this study were to develop a simple method for stress echocardiography in rats and to evaluate left ventricular function of the postinfarct remodeling heart during stress induced by rapid atrial pacing. METHODS: Myocardial infarction (MI) was induced in rats by ligation of left coronary artery. Rats with 3 week-old MI (n = 9) and sham operation (n = 7) were examined with transthoracic echocardiography during stress induced by transesophageal pacing. The stress protocol consisted of examinations at baseline; during 2 different pacing rates, at 360 and 600 bpm; and during recovery. Systolic blood pressure was measured at each step. RESULTS: Stroke volume decreased at pacing with 600 bpm in both groups compared with baseline and to pacing at 360 bpm (sham group, 0.15 +/- 0.01 vs 0.24 +/- 0.02 mL; MI group, 0.13 +/- 0.01 vs 0.31 +/- 0.02 mL, P <.05). Cardiac index increased at 360 bpm pacing compared with baseline and remained constant at the higher pacing rate in the sham-operated rats (246 +/- 34 vs 192 +/- 25 mL/kg, P <.05). In the MI rats, cardiac index decreased at 600 bpm pacing compared with baseline (195 +/- 9 vs 235 +/- 15 mL/kg, P <.01). Systolic blood pressure did not change during the stress protocol in the groups. CONCLUSION: Stress echocardiography induced by transesophageal pacing in rats is a feasible and simple method for evaluation of left ventricular function. This method may be useful for noninvasive evaluation of left ventricular function under stress conditions in small animal models of heart diseases.

Animals↗
PubMed1990

[A new Doppler echocardiography parameter of diastolic ventricular function].

The evaluation of flow velocities in left ventricular inflow tract (LVIT) by Doppler echocardiography gives information about the diastolic ventricular function. In late diastole, shortly after the flow velocity of atrial contraction V(A), we notice in the left ventricular outflow tract (LVOT) a laminar flow velocity directed to the aortic valve. The purpose of this study was to compare this flow velocity V(A*) in the LVOT with the flow velocity of the atrial contraction V(A), and the flow velocity of early diastole V(E) in LVIT, to determine whether such comparison would provide information concerning diastolic function. We studied three groups: 39 patients with left ventricular hypertrophy (HY) (mean age 56 +/- 12 y, 77% male), 41 patients with coronary heart disease (KHK) (mean age 53 +/- 10 y, 85% male) and 41 healthy subjects (N) (mean age 50 +/- 16 y, 51% male); all three groups were studied by pulsed Doppler from apical 4 chamber view in LVOT for maximal velocity (Vmax-A*) and time velocity integral of A* (TVI-A*), and in LVIT for maximal velocity of early diastole (Vmax-E), maximal velocity of atrial contraction (Vmax-A), ratio Vmax-E/Vmax-A, and the time velocity integrals (TVI-E, TVI-A). A slight correlation between Vmax-A* and Vmax-A was found (r = .60), being nearly the same as for TVI-A* and TVI-A (r = .64).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed2004

Radiofrequency ablation of atrial fibrillation.

UNLABELLED: Twenty-five patients (16 males, mean age 46 years) underwent radiofrequency ablation because of either paroxysmal (13 patients) or persistent atrial fibrillation (12 patients). Ablation aimed at earliest activation of spontaneous and catheter-induced repetitive ectopy in left and right atria and appendages, and pulmonary veins. Catheter-induced repetitive ectopy was defined as acute onset of a burst of rapid atrial premature beats on touching the wall, sustained irritability while at the spot and acute termination of rapid activity upon release of the catheter. Post-ablation patients received antiarrhythmic drugs to prevent tachycardias, thereby allowing reversal of atrial remodeling. RESULTS: Lone atrial fibrillation was present in 19 patients, 4 patients had hypertension and 2 patients coronary artery disease with preserved left ventricular function. The median duration of the history of atrial fibrillation was 4 years (range 1-14 years) and the median number of antiarrhythmic drug failures 5 (range 1-6). Ablation was successful, i.e. no recurrences of atrial fibrillation with or without antiarrhythmic drugs in eight patients (32%) during a median follow-up of 28 months (range 18-52). The median number of foci was 3 (range 2-6) and 2 (range 1-7) in the successfully and unsuccessfully treated patients, respectively. Minor complications occurred in three patients. CONCLUSIONS: Radiofrequency ablation of atrial fibrillation aiming at spontaneous and catheter-induced repetitive ectopy is a safe procedure. However, it is only successful in one third of the patients. Further investigations are warranted to identify the ideal patient, as well as to develop better ablation strategies.

Anti-Arrhythmia Agents↗
PubMed1970

The effect of physical training upon the mechanical and metabolic performance of the rat heart.

The dynamic and metabolic performance of rats conditioned by a swimming program (CH) and hearts of sedentary rats (SH) was studied in an isolated working rat heart apparatus. Heart rate, filling pressure, and afterload were controlled or kept constant, and heart weights were comparable in both groups. When compared with SH, CH had increased cardiac output and cardiac work. Atrial pacing at more rapid rates caused greater differences in these functions, and left ventricular pressure and maximal rate of pressure rise (dp/dt) became higher in CH than in SH. Atrial pacing was associated in CH with increased oxygen consumption but in SH by increased lactate and pyruvate production. When atrial filling pressure was elevated in order to perform ventricular function curves, CH showed greater dynamic responses than SH. There were also greater increments in oxygen consumption, and the ratio of aerobic to anaerobic energy production was also higher in CH. The mechanism of increasing oxygen consumption during stress in CH was mainly by improved coronary flow. In SH coronary flow did not change, but extraction of oxygen from the perfusing fluid increased. The results indicate that in physically trained rats the function of the heart as a pump is improved. These hearts have greater aerobic and mechanical reserve than hearts of sedentary animals. These effects appear to be at least partially due to improved mechanisms of oxygen delivery.

Animals↗
PubMed1995

[Syncopal ventricular tachycardia complicating paroxysmal atrial fibrillation in severe myocardial ischemia].

The authors report two cases of spontaneous paroxysmal atrial fibrillation closely followed by syncopal ventricular tachycardia resulting in cardiac arrest requiring defibrillation. Both patients, men aged 62 and 64 years, had a past history of myocardial infarction without arrhythmias; atrial fibrillation occurred during severe myocardial ischaemia; coronary arteriography showed tight stenoses of the left main coronary artery with normal left ventricular function. Ventricular tachycardia (or fibrillation) during spontaneous paroxysmal atrial fibrillation is a rare occurrence. This sequence of events has been described in patients with accessory conduction pathways or in hypertrophic cardiomyopathy. It is an exceptionally rare complication of ischemic heart disease with only a very few previously reported cases. Myocardial ischaemia is probably the cause of the arrhythmia in together with irregularity of the ventricular contractions responsible for long cycle-short cycle sequences which are particularly arrhythmogenic and changes in sympathetic tone.

Atrial Fibrillation↗
PubMed2003

Atrial structural remodelling and restoration of atrial contraction after linear ablation for atrial fibrillation.

AIMS: We determined late atrial function following a surgical linear endocardial radiofrequency (RF) ablation procedure that aimed to restore and maintain sinus rhythm (SR) in atrial fibrillation (AF). We tested the hypothesis that successful restoration of SR is accompanied by measurable mechanical atrial function that is at normal or near normal levels. METHODS: Forty-seven patients who underwent the surgical RF procedure at least 6 months previously (median 2.86 years; range: 0.6-4.2 years) were studied using an array of echocardiographic variables. Two patient groups (SR restored [RF-SR], persistent AF [RF-AF]) and an age matched control group were studied. Among the echocardiographic variables measured were left atrial (LA) size and volume, LA active fractional emptying and mitral annular displacement corresponding to atrial contraction (A' velocity) by Doppler tissue imaging. RESULTS: At long term follow up 29/47of patients who underwent the RF procedure were in SR with atrial contraction present echocardiographically. Of the patients initially restored to SR, the proportion remaining in SR at 3 years was 79% (SE 9%). The atrial-emptying fraction was reduced in comparison to that seen in normal controls (27+/-14% vs 46+/-10%). The A' velocity was decreased in the surgical RF cohort vs controls (4.4+/-1.3 vs 9.7+/-1.7cm/s; P=0.0001). Despite LA size preoperatively being similar in both surgical groups, atrial size decreased in those in whom SR was restored (48.6+/-7.6 vs 44.8+/-4.7mm; P=0.0001) but increased in those in whom AF persisted (48.2+/-8.1mm vs 52.3+/-7.8mm; P=0.0001). CONCLUSION: The radial pattern of linear radiofrequency ablation used in the present study resulted in restoration of SR and atrial function. Procedural success was independent of preoperative atrial size. Restoration of SR results in 'reverse' atrial remodelling and improved atrial function. However atrial function remains modestly impaired, either due to the ablation lesions or pre-existing atrial disease.

Aged↗
PubMed1993

Transient mitral regurgitation in acute glomerulonephritis.

During an epidemic of acute glomerulonephritis (AGN) 15 patients were studied by M-mode, cross-sectional, and Doppler echocardiography. All 15 patients had the classical signs of the disease including hematuria, proteinuria, edema, and consistent laboratory findings. There were 10 boys and five girls with a mean age of 8 years. Ten of the 15 patients had an enlarged left atrium and five of these 10 also had transient mild to moderate mitral regurgitation. In the five patients with mitral regurgitation the ratio of left atrium/aorta was 1.48; in the five patients with an enlarged left atria without evidence of mitral regurgitation the left atrium/aorta ratio was 1.34. All the patients had normal left ventricular dimensions, as well as ejection and shortening fractions. The findings of left atrial enlargement and mitral regurgitation disappeared gradually in all patients within 3 months. There was no correlation between the level of systemic blood pressure and the development of mitral regurgitation. A possible cause for these changes is fluid overload in the oliguric phase of the acute glomerulonephritis. The changes are transient and probably functional. There was no significant mitral valve or left atrial anomaly 3 and 6 months after hospital discharge.

Acute Disease↗
PubMed1999

Trandolapril reduces the incidence of atrial fibrillation after acute myocardial infarction in patients with left ventricular dysfunction.

BACKGROUND: Studies have suggested that ACE inhibitors have an antiarrhythmic effect on ventricular arrhythmias. Whether they have an effect on atrial fibrillation is unknown. METHODS AND RESULTS: We investigated the effect of ACE inhibition with trandolapril on the incidence of atrial fibrillation in patients with reduced left ventricular function secondary to acute myocardial infarction. The patients in this study were those who qualified for inclusion into the TRAndolapril Cardiac Evaluation (TRACE) study, a randomized double-blind placebo-controlled study and who had sinus rhythm on the ECG obtained at randomization. Patients who fulfilled the criteria for inclusion were randomized to treatment with the ACE inhibitor trandolapril or placebo and were followed up for 2 to 4 years. Development and time to occurrence of atrial fibrillation in one 12-lead ECG recorded at the outpatient visits was the primary end point of this investigation. Of the 1749 patients included in the TRACE study, 1577 had sinus rhythm on the ECG recorded at randomization. Of these patients, 790 were randomized to trandolapril treatment and 787 to placebo treatment. The groups differed only slightly with respect to baseline characteristics. A total of 64 patients developed atrial fibrillation during the 2- to 4-year follow-up period. Significantly more patients developed atrial fibrillation in the placebo group than in the trandolapril group, 5.3% (n=42) versus 2.8% (n=22), respectively, P<0.05. Cox multivariable regression analysis, adjusting for important baseline characteristics, revealed that trandolapril treatment significantly reduced the risk of developing atrial fibrillation (RR, 0.45; 95% CI, 0.26 to 0.76; P<0.01). CONCLUSIONS: The results from the present study demonstrate that trandolapril treatment reduces the incidence of atrial fibrillation in patients with left ventricular dysfunction after acute myocardial infarction.

Aged↗
PubMed2006

[Left ventricular remodeling in ischemic heart disease patients with signs and symptoms of chronic heart failure: an impact of the long-term exercise training].

Our study aimed at determining the effects of long-term exercise training on cardiorespiratory function and left ventricular remodeling in ischemic heart disease patients with the evidence of chronic heart failure, who had undergone a successful coronary angioplasty. One hundred thirty-five patients were entered into one-year study: 70 patients were assigned to the long-term exercise training group, and the remaining 65 persons--to the control group. All the patients were subjected to ergospirometry and echocardiography at study entry and at 6 and 12 months. At the outset, both groups showed no significant difference (P>0.05) in terms of ergospirometry findings. However, after 6 months, the rehabilitation group demonstrated significant changes (P<0.05) in exercise time, double product, RQ, AT VO2, VE/VO2, while the control group displayed no significant changes. After 12 months, the patients of rehabilitation group showed further increase in exercise time (from 5.6+/-1.9 min to 6.5+/-2.1 min) and AT VO2 (from 17.3+/-7.2 ml/kg/min to 20.8+/-5.4 ml/kg/min) indices (P<0.05). Those of double product and VE/VO2 decreased slightly when compared with findings at 6 months. RQ remained virtually at the same level, but significantly differed from the corresponding indices at the outset. Echocardiography performed at the entry and at 6 and 12 months revealed significant changes in systolic left ventricular function among the patients of rehabilitation group: wall movement index, ejection fraction as well as the left atrial long axis and left ventricular wall thickness. Echocardiographic changes indicate a positive impact of complex rehabilitative measures on systolic left ventricular function as evidenced by the ejection fraction and wall movement index values, as well as by regression of left ventricular wall thickness and left atrial long axis. Ergospirometry findings allow us to propose that the adequate choice of rehabilitative tools favorably affects the cardiovascular system, and this is reflected in exercise time and AT VO2 indices.

Angioplasty, Balloon, Coronary↗
PubMed1991

[Angiocardiographic evaluation of the left ventricular function in adult and pediatric subjects with interatrial defect of the ostium secundum type].

In order to assess left ventricular function in adults and children with ostium secundum atrial septal defect (ASD), 42 patients were examined by hemodynamic and angiocardiographic techniques. Patients were divided into three groups: Group I, 18 patients (mean age 42 years) with ASD; Group II, 14 patients (mean age 9 years) with ASD; Group III, 10 patients without cardiopathies who represented the control group. The following parameters of ventricular function were assessed: left ventricular end diastolic volume, global and regional left ventricular ejection fraction, left ventricular telediastolic pressure, mean pulmonary artery pressure, the ratio between pulmonary flow and systemic flow (QP/QS). Group I patients showed higher values of left ventricular end diastolic pressure and mean pulmonary artery pressure (16 +/- 0.6 mmHg; 33 +/- 1.5 mmHg) in relation to those of Group II (5.1 +/- 0.4 mmHg; 14 +/- 1.4 mmHg) and Group III (8.1 +/- 0.5 mmHg; 18 +/- 1.6 mmHg). In both cases the difference was statistically significant (p less than 0.001). A significant difference (p less than 0.05) was also noted in the incidence of mitral valve prolapse between patients in Group I and II. There was no significant difference (p = NS) however, between overall ejection fraction values in the three groups of patients; a lower regional ejection fraction (postero-basal segment) was recorded in Group I patients with mitral valve prolapse in comparison to patients in the other two groups (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed2004

Effects of right atrial and ventricular DDD pacing on cardiac function and ventricular contraction synchrony.

BACKGROUND: Right ventricular apical pacing has been reported to reduce cardiac performance. But there are few reports on the effects of dual chamber (DDD) pacing on cardiac function compared to sinus rhythm. In this study, we evaluated the effects of right atrial and ventricular DDD pacing on cardiac function and ventricular contraction synchrony using equilibrium radionuclide angiography. METHODS: Ten patients implanted with a right atrial and ventricular DDD pacemaker underwent equilibrium radionuclide angiography. The scintigraphic data were obtained during sinus rhythm and pacing rhythm. Cardiac function parameters were obtained semimanually. Phase analysis was used to study the ventricular activation sequence and ventricular synchrony. RESULTS: The left ventricular 1/3 ejection fraction decreased significantly during pacing compared with that during sinus rhythm [(23.4 +/- 6.1)% vs (27.7 +/- 4.5)%, P = 0.01]. Regional ejection fraction also decreased during pacing, although the difference was not statistically significant. Phase analysis showed that the right ventricle was activated earlier than the left ventricle during pacing, and that the phase shift was significantly greater during pacing than that during sinus rhythm [64.13 degrees +/- 16.80 degrees vs 52.88 degrees +/- 9.26 degrees, P = 0.007]. The activation of both ventricles occurred simultaneously during sinus rhythm, with the activation sequence from proximal septum or base of left ventricle to apex. The earliest activation during pacing occurred at the right ventricular apex, and subsequently spread to the base and left ventricle. CONCLUSION: Right atrial and ventricular DDD pacing impairs left ventricular systolic function and ventricular synchrony.

Cardiac Pacing, Artificial↗
PubMed1991

[Radionuclide assessment of left ventricular diastolic function in patients with mitral stenosis before and after percutaneous transvenous mitral commissurotomy; use of list mode method in patients with atrial fibrillation].

To evaluate the effect of percutaneous transvenous mitral commissurotomy (PTMC), equilibrium radionuclide angiocardiography was performed in eight patients with mitral stenosis who had atrial fibrillation. Accurate cardiac function in patients with atrial fibrillation is difficult to assess, since the wide fluctuation of cardiac cycle makes the ventricular hemodynamics variable. A new processing algorithm was devised to make multiple gated images discriminated from a heart rate distribution histogram. We obtained about 1,000 beats data by list mode acquisition, and processed a heart rate distribution histogram. The data in the area +/- 5% of the most frequent heart rate were converted into frame mode and a representative time activity curve was derived. Mitral valve area calculated by echocardiography increased from 1.3 +/- 0.5 to 2.0 +/- 0.6 (cm2) significantly (p less than 0.01). The mean transmitral pressure gradient measured by catheterization decreased from 12.4 +/- 5.9 to 4.9 +/- 3.7 (mmHg) significantly (p less than 0.01) and the clinical symptoms improved in all patients. The change in left ventricular ejection fraction from 43 +/- 9 to 48 +/- 13 (%) was not statistically significant, but peak filling rate (PFR) derived from the time activity curve increased from 1.5 +/- 0.3 to 2.0 +/- 0.4 (EDV/sec) significantly (p less than 0.01). Thus PFR is a noninvasive parameter that can evaluate the effect of PTMC.

Adult↗
PubMed1997

Participation of the pituitary-thyroid axis in the cardiovascular system in elderly patients with congestive heart failure.

The relationship between the pituitary-thyroid axis and the cardiovascular system in patients with congestive heart failure (CHF) remains unknown. Therefore, we attempted to determine serum levels of thyroid hormones in relation to plasma atrial natriuretic peptide (ANP) levels and left ventricular (LV) function in patients with CHF. The echocardiographic ejection fraction significantly correlated with the thyroid stimulating hormone (TSH) (p < 0.005) and free triiodothyronine (FT3)/free thyroxine (FT4) ratio (p < 0.005), respectively, in patients with CHF but not in control subjects. TSH was positively correlated with the FT3/FT4 ratio (p < 0.01) in CHF. In patients with CHF, TSH and thyroid hormones may participate in regulatory mechanisms of the cardiovascular system and altered thyroid hormone metabolism, which was characterized by a euthyroid sick syndrome.

Aged↗
PubMed1976

An intrathoracic solenoid drive system for chronic left ventricular bypass.

The performance of an implantable Left Ventricular Assist System (LVAS), utilizing an advanced solenoid energy converter, has been extensively studied in vivo. For optimum system efficiency, reliability and responsiveness, the energy converter and blood pump are integrated into a single compact unit, which is implanted intrathoracically in an 80 Kg calf. The MK19 LVAS is battery operated and controlled by a miniature analog computer and is completely self-regulating. The maximum hemodynamic power provided by this circulatory assist system is 4 watts with cardiac outputs up to 10 L/min and a total system efficiency of 30%. LVAS function has been studied in a series of 19 calf experiments progressing through acute, model and chronic evaluations. Development of the implantation protocols and hemodynamic characterization were achieved in a series of 8 acute experiments. Long-term studies were conducted for periods up to 43 days in a series, including 2 control experiments using non-functional models and 9 functional LVAS chronic experiments. Aortic, left ventricular and left atrial pressures, pulmonary artery flow and pump outflow were monitored with chronically implanted transducers. A dedicated minicomputer provided real-time hemodynamic analysis and continuous surveillance of physiologic and LVAS parameters. In acute studies and in the immediate post-operative period of chronic experiments, synchronous LVAS operation reduced peak LV pressures to 30 mm Hg with cardiac outputs of 5 to 7 L/min. In chronic studies, with recovery of normal LV function, long-term synchronous operation was maintained, without capture of the total cardiac output and with significantly reduced ventricular unloading.

Animals↗
PubMed2006

Left atrial volume in normal Japanese adults.

BACKGROUND: Two-dimensional (D) echocardiography-derived left atrial (LA) volume has been shown to provide a more accurate assessment of LA size than the M-mode LA dimension. Our objective was to provide reference ranges of LA volume in healthy Japanese adults. METHODS AND RESULTS: The study subjects consisted of 105 Japanese adults, with a mean age of 39+/-13 years (range 20-63 years old). All subjects had normal ejection fraction (>55%), no wall motion abnormalities, normal diastolic function, no valvular disease, and normal sinus rhythm. The maximum LA volume, at left ventricular end-systole just before the opening of the mitral valve, was measured by using the bi-apical (4- and 2-chamber views) Simpson's rule. Both the absolute LA volume and the volume corrected by body surface area (LA volume index) were obtained. The LA volume ranged from 21 to 53 ml (mean 37+/-8 ml) and the LA volume index ranged from 13 to 30 ml/m(2) (mean 22+/-4 ml/m(2)). The mean LA volume index + 2SDs was 30 ml/m(2). CONCLUSIONS: Recognition of the upper limits of LA volume in normal Japanese subjects is of particular clinical relevance because it offers the opportunity of pathological LA remodeling diagnosis.

Adult↗
PubMed2004

Restitution of sinus rhythm plus stentless mitral valve replacement at three years.

BACKGROUND AND AIM OF THE STUDY: The study aim was to examine results after stentless mitral valve (SMV) replacement (Quattro) and restitution of physiological cardiac rhythm by intraoperative left atrial ablation therapy. METHODS: Twenty patients (13 females; mean age 69.7 +/- 5.9 years) with severe degenerative mitral valve disease (six with valve stenosis, six with valve incompetence, eight with combined lesion) were prospectively evaluated since 1998. The mean NYHA functional class was 3.2 +/- 0.4, and cardiac index 1.8 +/- 0.5 l/min/m2. Ablation therapy was performed by inducing left atrial linear lesion lines to avoid reentrant circuits. RESULTS: Surgery was performed using conventional sternotomy (n = 10) or lateral minithoractomy (n = 10). Sinus rhythm was successfully restituted in 17 patients either postoperatively or in the long term (success rate 85%). However, three patients required DDD-pacemaker implantation, and another three had to be discharged with persistent atrial fibrillation. Intermittent medical therapy (sotalol or amiodarone) was required in nine patients postoperatively, in four patients at six months, and in two patients at one-year follow up. One patient was reoperated on for paravalvular leak after one year, but subsequently died due to sepsis. In the other patients, echocardiographic control proved good SMV function with atrial contraction. CONCLUSION: Restitution of physiological cardiac function is possible by combined stentless MV implantation and left atrial ablation therapy. A persistent benefit, without need for additional re-intervention, was shown at mid-term follow up.

Aged↗
PubMed1991

Coronary hemodynamics and myocardial metabolism in patients with syndrome X: response to pacing stress.

Coronary hemodynamics, myocardial metabolism and left ventricular function at rest and after incremental atrial pacing were evaluated in 12 patients with stress-induced angina and ST segment depression, angiographically normal coronary arteries and no evidence of spasm, generally labeled as syndrome X, and in 10 normal subjects. At baseline study, great cardiac vein flow was comparable in patients and control subjects. During pacing, an equivalent rate-pressure product was reached in the two groups, but the slope of the relation between rate-pressure product and great cardiac vein flow was significantly less steep in patients than in normal subjects (0.0027 vs. 0.0054 ml/mm Hg.beat, p less than 0.001). Nevertheless, the left ventricular ejection fraction was comparable in both groups at rest (66 +/- 6% vs. 71 +/- 7%, p = NS) and during pacing (71 +/- 7% vs. 66 +/- 5%, p = NS). At baseline study, myocardial glucose extraction was more efficient in patients with syndrome X (p less than 0.05), but net myocardial exchange of pyruvate and alanine was, respectively, smaller and greater than in control subjects. Lactate was extracted to a similar extent in the two groups and in no instance was net lactate release observed during pacing or recovery. During pacing and recovery, patients with syndrome X showed net pyruvate release, unlike the control subjects in whom net pyruvate exchange was positive. In addition, patients with syndrome X continued to show net myocardial extraction of alanine during spacing and recovery, whereas normal subjects produced alanine throughout the study. Myocardial carbohydrate oxidation increased significantly during maximal pacing in normal subjects but not in patients, in whom it always remained below (p less than 0.01) the concurrent rate of myocardial uptake of carbohydrate equivalents (glucose, lactate, pyruvate, alanine). Myocardial energy expenditure was significantly lower in patients than in control subjects at maximal rate-pressure product levels (p less than 0.01). The metabolic pattern in patients with syndrome X therefore is not consistent with classic ischemia, although differences in the net exchange of circulating substrates (glucose, pyruvate, alanine) can be demonstrated. Thus, in patients with syndrome X, the symptoms, electrocardiographic signs and impairment in the increase in great cardiac vein flow during pacing coexist with preserved global and regional left ventricular function and myocardial energy efficiency.

Angina Pectoris↗
PubMed2002

Doppler echocardiographic evaluation of right ventricular diastolic function in hypertrophic cardiomyopathy.

AIMS: Left ventricular diastolic function in patients with hypertrophic cardiomyopathy has been adequately studied. In contrast there are few studies concerning right ventricular diastolic function in hypertrophic cardiomyopathy. We studied right ventricular diastolic function in patients with hypertrophic cardiomyopathy using Doppler echocardiography. METHODS AND RESULTS: We studied 20 patients with hypertrophic cardiomyopathy (mean age 43.6+/-13.8 years) and 20 healthy volunteers (control group, mean age 43+/-13.8 years). We calculated left ventricular and right ventricular diastolic indices using pulsed Doppler echocardiography. Hypertrophic cardiomyopathy patients compared with controls had significantly lower right ventricular-E/A ratio (1.01+/-0.40 vs 1.30+/-0.28, P<0.04), significantly prolonged right ventricular isovolumic relaxation time (170+/-72 vs 32+/-23 ms, P<0.001), and also significantly prolonged right ventricular deceleration time (160+/-58 vs 118+/-35 ms, P<0.01). There was also strong significant correlation between right ventricular deceleration time and left ventricular deceleration time (r=0.78), right ventricular-E/A ratio and left atrial filling fraction (r=-0.55) and between right atrial filling fraction and left atrial filling fraction (r=0.75). CONCLUSIONS: Right ventricular diastolic function in patients with hypertrophic cardiomyopathy is impaired, reflecting abnormal relaxation. Right ventricular diastolic indices correlate well with those of left ventricle.

Adolescent↗