Left Ventricular Outflow Gradient Research Articles

Early remodelling of left ventricle and improvement of myocardial performance in patients after percutaneous transluminal septal myocardial ablation for hypertrophic obstructive cardiomyopathy

Background: Percutaneous transluminal septal myocardial ablation (PTSMA) reduces left ventricular outflow (LVOT) gradient in patients with hypertrophic obstructive cardiomyopathy (HOCM) and leads to symptomatic improvement. Effects of PTSMA on left ventricular performance are currently unknown. The purpose of this study was to evaluate changes in the left ventricular performance using Doppler index of myocardial performance (sum of isovolumic contractile and relaxation times divided by left ventricular ejection time) and left ventricular remodelling after PTSMA for HOCM. Methods: Twenty-five patients with symptomatic HOCM underwent echocardiography-guided PTSMA procedure. Clinical and echocardiographic data were collected at baseline and 3 months after PTSMA. Results: PTSMA procedures were uneventful, in one patient (4%), pacemaker implantation was needed for sustained complete heart block after the procedure. At 3-month follow-up, the maximal LVOT gradient decreased from 68±39 to 18.6±12 mmHg ( P<0.001), the provoked maximal LVOT gradient decreased from 128.8±59 to 25±21.4 mmHg ( P<0.001), and basal septal thickness decreased from 21.7±4 to 15.2±3 mm ( P<0.001). The improvement of the index of myocardial performance (from 0.65±7 to 0.56±11; P<0.001) was associated with neither significant change in left ventricular ejection fraction nor left ventricular ejection time. There was no significant difference in the left ventricular dimension at baseline and at follow-up. All patients reported a significant improvement in symptoms at follow-up, the mean NYHA class decreased from 2.6±0.7 to 1.4±0.7 ( P<0.001), and the number of patients suffering from episodes of syncope or attacks of dizziness decreased from 13 to two during the 3-month follow-up. Conclusions: PTSMA is a safe, effective and reproducible method in the treatment of highly symptomatic patients with HOCM. This procedure results in a significant relief of symptoms associated with decrease in LVOT gradient and thickness of basal interventricular septum. Positive changes in Doppler IMP suggest possible improvement of left ventricular function.

Left ventricular remodeling after pulmonary autograft aortic valve replacement: evaluation with color-Doppler echocardiography and magnetic resonance imaging.

The superior hemodynamic performance of the pulmonary autograft in aortic position is expected to reflect complete regression of hypertrophy and improved ventricular function. We evaluated and compared early and midterm transthoracic color-Doppler echocardiography (TTE) and magnetic resonance imaging (MRI) assessment concerning left ventricular (LV) function, LV mass regression, and performance of the semilunar valves. A total of 42 consecutive patients, mean age 36 +/- 6 years (range 15 to 56 years), were studied. TTE and MRI were performed preoperatively, at discharge, and at 6 and 12 months postoperatively. Left ventricular diameters and function and LV wall thickness and mass were assessed. There was no early and one late postoperative death. Maximum and mean LV outflow gradients were significantly reduced (p = 0.0001 and p = 0.0001, respectively). There was a significant reduction in left ventricular mass to near normal for all patients (p = 0.001) seen after 6 months. This was paralleled by significant reductions in the interventricular septum and posterior wall thickness, but difference was slight during further follow-up. There was a strong correlation between the results obtained by TTE and MRI for LV mass and ejection fraction (r = 0.86 and 0. 87, respectively). The pulmonary autograft operation gives excellent results that are translated into greater, rapid, and near complete regression of LV hypertrophy. Magnetic resonance imaging is a sensitive and noninvasive methodology that provides reliable visualization and quantification of ventricular performance.

Evolving indications for permanent pacemakers.

New indications for permanent cardiac pacing have been developed in recent years, with numerous studies demonstrating improved clinical outcomes in a variety of disorders. Because hypertrophic obstructive cardiomyopathy, dilated cardiomyopathy, heart failure, neurocardiogenic syncope, and atrial fibrillation are common conditions, every clinician should be aware of evolving alternative therapies for them. Observational studies in patients with refractory, symptomatic hypertrophic obstructive cardiomyopathy and significant left ventricular outflow gradient at rest suggest that cardiac pacing may result in symptomatic and hemodynamic improvement. Clinical trials have not shown conclusive evidence regarding the long-term benefit from pacing in these patients, and it is unclear whether pacing will be a preferred treatment option. Preliminary data suggest that pacing is a viable adjunctive therapeutic approach for improving symptoms in patients with dilated cardiomyopathy and heart failure. Mortality benefit has yet to be established, but it is to be hoped that ongoing randomized clinical trials will provide definitive information on that issue. Patients with refractory neurocardiogenic syncope or those who are intolerant of medical treatment may benefit from pacing therapies, especially those that use rate-drop sensor algorithms. Biatrial pacing has emerged as a technique that resynchronizes atrial electrical activity and has been shown to prevent atrial fibrillation. Multisite atrial pacing for the prevention of atrial fibrillation is considered investigational but seems promising. Newer indications for pacing are expected to result in improved clinical outcomes for hypertrophic obstructive cardiomyopathy, dilated cardiomyopathy and heart failure, neurocardiogenic syncope, and the prevention of atrial fibrillation.

Heart rate variability in hypertrophic obstructive cardiomyopathy: association with functional classification and left ventricular outflow gradients

Background: The aim of this study was to investigate cardiac autonomic control in patients with hypertrophic obstructive cardiomyopathy (HOCM) and to assess the indexes of heart rate variability (HRV) in relation to the clinical and echocardiographic features. Methods and results: Twenty-three patients (17 male, six female: mean age 43±11) with HOCM and 18 healthy volunteers were included. M-mode and two-dimensional echocardiography, pulsed and continuous-wave Doppler studies were obtained. All patients and volunteers underwent continuous 24-h ambulatory ECG monitoring. Time domain variables considered in this study were standard deviation of mean R–R intervals (SDNN), root mean-squared successive difference (RMSSD) and percentage of cycles differing from the preceding one by more than 50 ms (PNN 50%). Patients were compared to detect associations between indices of heart rate variability, left ventricular outflow tract obstruction and clinical status. Heart rate variability parameters were also correlated with the echocardiographic and clinical characteristics of the patients. Both New York Heart Association (NYHA) functional class I–II patients (group I) and NYHA III–IV patients (group II) had lower values of SDNN, RMSSD and PNN 50% when compared with the control group ( P<0.001, P<0.05 and P<0.01, respectively, for group I and P<0.001, P<0.001 and P<0.001, respectively, for group II). Time domain heart rate variability parameters were found to be significantly correlated with the subaortic dynamic obstruction. Conclusion: Heart rate variability is reduced in HOCM and well correlated with the degree of subaortic obstruction. Heart rate variability indices are also sensitive markers of the functional status.

New treatment methods for patients with hypertrophic obstructive cardiomyopathy.

The past decade has witnessed significant advancements in the treatment of patients with refractory symptoms due to hypertrophic obstructive cardiomyopathy. In this publication, we will review the impact of dual-chamber pacing and nonsurgical septal reduction therapy with ethanol on the outcome of these patients. Both therapies have been shown to result in significant reductions in the left ventricular outflow gradient, which was an entry criterion in all the reported studies, along with symptomatic relief from symptoms of angina and dyspnea on midterm follow-up. Studies currently are under way to compare dual-chamber pacing and nonsurgical septal reduction therapy with myotomy-myomectomy, which is considered to be the standard of care in these patients.

Natural history and surgical outcomes for isolated discrete subaortic stenosis in children

OBJECTIVETo document the natural history and surgical outcomes for discrete subaortic stenosis in children.DESIGNRetrospective review.SETTINGTertiary care paediatric cardiology centres.PATIENTS92 children diagnosed between 1985 and 1998.MAIN OUTCOME MEASURESEchocardiographic left ventricular outflow...

Comparison of dual-chamber pacing versus septal myectomy for the treatment of patients with hypertrophic obstructive cardiomyopathy : A comparison of objective hemodynamic and exercise end points

OBJECTIVESThe purpose of this study was to compare the treatment effects of septal myectomy with dual-chamber pacing in patients with hypertrophic obstructive cardiomyopathy (HOCM).BACKGROUNDThe optimal treatment for symptomatic patients with drug-refractory HOCM is unknown. Both dual-chamber pacing and surgical myectomy may result in subjective symptom improvement. However, no direct comparisons with objective end points have been reported.METHODSThirty-nine patients with symptomatic HOCM were analyzed in this concurrent cohort study. Twenty patients underwent surgical myectomy, and 19 received dual-chamber pacemakers based on patient preference. These patients had prospective baseline and follow-up evaluations including physician assessment, echocardiography and standardized metabolic treadmill exercise testing.RESULTSBaseline symptom status, left ventricular outflow tract gradients, exercise times and maximal oxygen consumption peak were similar between the two groups. Left ventricular outflow gradient was reduced from 76 ± 57 to 9 ± 17 mm Hg (p = 0.0001) after myectomy, and from 77 ± 61 to 55 ± 39 mm Hg (p = 0.07) after pacing (p = 0.02 for comparison with myectomy). Ninety percent of myectomy patients experienced symptomatic improvement as compared with 47% in the pacing group. Exercise duration increased significantly from 6.6 ± 2.8 to 8.7 ± 3.0 min (p = 0.0003) after myectomy compared with a change from 6.4 ± 2.1 to 7.0 ± 2.2 min (p = NS) in the pacing group. Maximal oxygen consumption increased from 19.4 ± 6.4 to 22.2 ± 6.5 ml/kg/min after myectomy (p = 0.004), whereas the pacing group did not experience any significant change (19.6 ± 6.5 vs. 20.1 ± 6.5 ml/kg/min, p = NS).CONCLUSIONSSurgical myectomy and dual-chamber pacing improve subjective measures of functional status in patients with symptomatic HOCM. In this nonrandomized study, myectomy offered greater reduction in left ventricular outflow tract gradients and larger improvements in objective measures of patient symptoms and functional status when compared with dual-chamber pacing.

Full ventricular capture indicated by the QT interval function.

The atrioventricular (AV) interval is critical in dual chamber (DDD) pacing in patients with hypertrophic obstructive cardiomyopathy (HOCM) to obtain full ventricular capture (FVC) with maximal reduction of the left ventricular (LV) outflow gradient and optimal LV diastolic filling. We studied the relationship of FVC, fusion, spontaneous AV conduction, and the QT interval. 11 patients with various cardiac diseases and stable AV conduction received a QT sensing Diamond, Vitatron, DDD pacemaker. Software was downloaded into the pacemaker. In the DDD pacing mode, with the QT interval measured from the ventricular pacing stimulus to the end of the T wave, the AV interval was shortened from 400 ms, in 20-ms steps, to 90 ms. At 90 ms the stimulation rate was increased by 30 beats/min and the AV interval was increased stepwise. FVC and fusion was examined on the surface ECG. At 400 ms interval, spontaneous AV conduction inhibited the pacemaker. Shortening the AV interval resulted in pacing with a short QT interval. Further reduction of the AV interval resulted in a longer QT interval up to a point where the QT interval became stable. This point, the bending point in the plot of measured QT interval versus shortened AV intervals, coincided with the point of FVC. The relation of the QT-AV interval plot and the point of fusion was comparable when lengthening the AV interval at a 30 beats/min faster stimulation rate. The bending point in the QT interval versus AV interval plots showed a good correlation with the FVC and fusion points observed on ECG. The results suggest that automatic discrimination between fusion and full capture using QT interval measurements may be feasible.

Guiding of Percutaneous Transcoronary Septal Myocardial Ablation in Hypertrophic Obstructive Cardiomyopathy by Myocardial Contrast Echocardiography:

Percutaneous transluminal septal myocardial ablation (PTSMA) by alcohol injection into septal branches (SB) of the left coronary artery has evolved as a promising therapeutic option for selected patients with obstructive hypertrophic cardiomyopathy (HOCM). Originally, probatory balloon occlusion of the target vessel was considered to be predictive for definitive reduction of left ventricular outflow gradients (LVOTG). The need for additional information regarding the exact site and extension of the therapeutic septal infarction is demonstrated by a case report. In this patient, myocardial contrast echocardiography (MCE) was performed prior to alcohol injection and showed that the septal area corresponding to LVOTG formation was supplied by a SB originating atypically from an intermediate branch. PTSMA guided by MCE led to complete LVOTG elimination without sustained rhythm disturbances and with a minimum CK rise.

Hypertrophic Cardiomyopathy in Greece: Clinical Course and Outcome

Evaluation of clinical course and outcome of hypertrophic cardiomyopathy in a representative Greek population. Hypertrophic cardiomyopathy is characterized by unexplained left ventricular hypertrophy and varied clinical expression. Recent studies suggest ethnic differences. One hundred seventy-four consecutive Greek patients (117 male, 57 female, age 47+/-16 years) from 143 different families were assessed at the Department of Cardiology of the University of Athens, Greece, and the State Cardiac Department, Hippokration Hospital, both located in Athens, Greece. To reduce selection bias, referral was based on disease diagnosis irrespective of clinical status or treatment needs. All patients were examined clinically, echocardiographically, and by ECG ambulatory monitoring at 6-month intervals for a period of 74+/-22 months (range, 8 to 108 months). Most patients (n = 156, 89.7%) were in New York Heart Association (NYHA) functional class I or II. The disease was familial (at least one affected first-degree relative) in 81 of the 143 families (56.6%), and in 19 of these (13.3%) there was familial history of sudden cardiac death. At initial examination, intraventricular septal thickness was 17.3+/-4.1 mm and posterior wall thickness was 13.7+/-3.8 mm and a left ventricular outflow gradient >30 mm Hg was present in 58 patients (33.3%). Similar were the findings during the last examination (17.5+/-4.3 mm, 13.5+/-4.4 mm, and 56 (32.2%, respectively, p = not significant). Episodes of nonsustained ventricular tachycardia were noted in 15 patients (8.6%). There were eight deaths during follow-up: four sudden deaths and four from intractable heart failure. Syncope was reported by all patients who died. The annual mortality in this study was 1%. Syncope and NYHA class were the only predictors of outcome. In this representative Greek patient cohort with hypertrophic cardiomyopathy, the arrhythmogenic substrate was modest and the clinical course benign. Sudden cardiac death was infrequent and syncope, functional class, and ventricular arrhythmias were the only predictors of a poor outcome.

Altered autonomic cardiac control in hypertrophic cardiomyopathy. Role of outflow tract obstruction and myocardial hypertrophy.

The goal of this study was to investigate the role of left ventricular outflow tract obstruction and myocardial hypertrophy on autonomic cardiac function in patients with hypertrophic cardiomyopathy. The sympatho-vagal function was evaluated by spectral analysis of heart rate variability in 28 patients with hypertrophic obstructive cardiomyopathy, 22 patients with hypertrophic non-obstructive cardiomyopathy, 12 with systemic hypertension and left ventricular hypertrophy and 28 healthy subjects. Left ventricular out-flow tract pressure gradient in patients with hypertrophic cardiomyopathy was evaluated by echo-Doppler methods and the quantitative assessment of left ventricular hypertrophy was based on an echocardiographic index. At rest, patients with hypertrophic non-obstructive cardiomyopathy showed normal spectral patterns, while in patients with hypertrophic obstructive cardiomyopathy and in patients with systemic hypertension we observed, respectively, a significant reduction and increase in the low frequency component relative to the control (P < 0.05). During tilt, the physiological increases in the low frequency component and in the low to high frequency ratio were markedly blunted, or even reverted, only in patients with hypertrophic obstructive cardiomyopathy. In these patients, the heart rate increase during tilt was delayed in comparison to the other groups. Finally, in the hypertrophic obstructive cardiomyopathy group, the impairment of sympathetic activation (lack of increase in the low frequency component during tilt) was significantly correlated to the echocardiographic index of left ventricular hypertrophy (r = -0.800, P < 0.001) rather than to the left ventricular outflow tract pressure gradient (r = 0.295, P: ns). Among patients with hypertrophic cardiomyopathy, only those with outflow tract obstruction show spectral signs of altered autonomic cardiac control. Within this group, the autonomic dysfunction appears to be correlated to myocardial hypertrophy rather than to left ventricular outflow tract obstruction.

Hemodynamic Performance of Small Aortic Valve Bioprostheses: Is There a Difference?

Background. There is the potential for left ventricular outflow obstruction when small aortic valve bioprostheses are employed in normal-sized or large adults. It has been hoped that bovine pericardial valves would improve hemodynamic performance in the smaller tissue valve sizes.Methods. To determine in vivo hemodynamic performance of heterograft aortic valve prostheses, we analyzed echocardiographic data from patients receiving 21- or 23-mm Carpentier-Edwards pericardial, Medtronic Intact, and Carpentier-Edwards porcine bioprostheses. In addition, data from 19-mm Carpentier-Edwards pericardial valves were included for comparison of hemodynamic performance between valve sizes. Doppler echocardiography was performed in 151 patients within 2 weeks of operation. Left ventricular outflow gradient was derived from continuous Doppler measurements of flow velocity, and effective orifice area was calculated by the continuity equation.Results. There were statistically significant differences in hemodynamic performance of different sized prostheses for each valve type (effective orifice area, p < 0.01; valvular gradient, p < 0.03). There were, however, no significant differences in effective orifice area or mean gradient for different valve types within each size category.Conclusions. The in vivo hemodynamic performance of these three different aortic valve heterograft bioprostheses is similar. Patient–prosthesis mismatch with heterograft prostheses, as demonstrated by the indexed effective orifice area can be avoided by appropriate sizing and use of annular enlarging techniques when necessary.(Ann Thorac Surg 1997;63:362–6)

721-2 Aortic Valve Repair and Replacement After Balloon Aortic Valvuloplasty in Children

Little is known about the incidence, indications and results of surgical repair or replacement of the aortic valve following balloon valvuloplasty for congenital aortic stenosis in children. This study was designed to evaluate patterns of failure requiring surgery after balloon aortic valvuloplasty (BAli.) of congenital AS and to review our experience with successful repair, rather than replacement, of some aortic valves after BAV. From 1986 to 1994, 54 patients with congenital AS aged 1 day-27 years (mean ± sd; 8 ± 6 yrs) underwent BAV. Eighteen patients (33%) required surgery a mean of 33 ± 25 mos (range 1 to 80 mos) following BAV. because of severe AI in 10 patients and recurrent or residual AS in 8 patients. Severe AI was invariably due to avulsion of a cusp from the annulus with resulting cusp prolapse and insufficiency. Actuarial freedom from surgical intervention was 90 ± 4% at 1 year, 79 ± 6% at 3 years, and 64 ± 7% at 6 years. The need for aortic valve surgery was unrelated to age at the time of BAV. Surgical intervention consisted of valve replacement in 11 patients and aortic valve repair in 7 patients. Repair techniques included reattachment of an avulsed cusp to the aortic annulus, relief of commissural fusion, and debridement of thickened cusps. All survived operation and are alive 23 ± mos (range 2–44 mos) following aortic valve operation. LV outflow gradient has been well relieved in all patients undergoing valve replacement. The 7 valve repair patients have been followed 17 ± 10 mos (range 4–33 mos). Echocardiographic follow-up of the valve repair patients revealed mild levels of residual AS and mild (1–2+) AI in all patients. Aortic valve surgery is required in 5–10% of patients yearly following BAli. and appears to be unrelated to age at the time of BAV. AI predominates over AS as an indication for operative intervention. Valve repair can be applied in some patients following BAV. with good intermediate-term results and may delay the need for aortic valve replacement.

Effects of nicorandil on left ventricular systolic and diastolic function in patients with hypertrophic cardiomyopathy.

Various evidence suggest that myocardial ischemia is a major factor in the progression of hypertrophic cardiomyopathy (HCM). In this study, we investigated the effects of nicorandil on left ventricular (LV) systolic and diastolic function in 12 symptomatic patients with HCM using echocardiography and radionuclide angiography. Nicorandil (6 mg), when administered intravenously, produced no significant changes in any parameter, including LV filling dynamics. However, accelerated LV peak early filling velocity (0.51 +/- 0.13 to 0.59 +/- 0.14 m/sec, p < 0.01), and reduced peak velocity in atrial contraction (0.54 +/- 0.17 to 0.50 +/- 0.15 m/sec, p < 0.05) were observed by Doppler echocardiography after 4 weeks of oral administration of 10 mg nicorandil 3 times daily. This oral administration did not affect heart rate, blood pressure, LV outflow gradient, or LV systolic function. The same favorable results were observed in a wall motion analysis with radionuclide angiography: peak filling rate (PFR) in global LV (3.21 +/- 0.76 to 3.52 +/- 0.87 end-diastolic volume (EDV)/sec, p < 0.02), and apical (4.73 +/- 1.18 to 5.42 +/- 1.55 EDV/sec, p < 0.01) and lateral (4.78 +/- 1.60 to 5.52 +/- 1.51 EDV/sec, p < 0.05) segments was increased, and the time to peak filling rate (TPF) in septal (245 +/- 31 to 203 +/- 40 msec, p < 0.01) and lateral (222 +/- 54 to 193 +/- 34 msec, p < 0.05) segments was reduced. These findings indicate that nicorandil has beneficial effects on LV diastolic function in HCM. These favorable effects may be due to the improvement of subendocardial ischemia.

Severe left ventricular dynamic outflow tract gradient secondary to localized septal hypertrophy and concomitant acute ischaemic parietal dyssynergy

Localized basal septal hypertrophy (LSH) is usually an incidental echocardiographic finding and, as opposed to asymmetric hypertrophic cardiomyopathy (AHC), is of no clinical significance. We report a case of a patient with LSH who developed a severe left ventricular outflow gradient during acute myocardial ischaemia, apical akinesis and compensatory hyperkinesis of basal parietal segments.

Recognition and management of accessory mitral tissue causing severe subaortic stenosis

Failure to recognize the presence of accessory mitral tissue causing subaortic stenosis can lead to not only the performance of inappropriate operations, but the persistence and recurrence of obstruction or even death. Over a 12-month period, we treated 2 children with severe subaortic stenosis caused by accessory mitral tissue. In 1 patient, who was 4 years old, the echocardiogram showed the accessory mitral tissue to be attached to the anterior mitral leaflet and ballooning into the subaortic area. The other patient, as a newborn, underwent simultaneous repair of a complete canal defect and coarctation. Two years later, the patient was seen because of syncopal episodes, progressive mitral insufficiency, and subaortic stenosis thought to be caused by anterior displacement of the anterior mitral leaflet. Mitral valvuloplasty and a conal enlargement procedure were planned. Intraoperatively, after the mitral valvuloplasty had been done, the subaortic stenosis was found to be due to a tight subaortic ring formed by accessory mitral tissue located at the septum and its fibrous extension to the anterior mitral leaflet. In both patients, excision of the accessory mitral and fibrous tissues resulted in a wide-open subaortic area. Both patients had an uneventful hospital course, and follow-up echocardiography showed no noteworthy residual left ventricular outflow gradient. We believe that increased awareness and sophisticated edchocardiographic techniques should lead to an increased recognition of accessory mitral tissue causing subaortic stenosis. Simple resection of the accessory mitral tissue and its secondary fibrous tissues can be curative.

Altered cardiac hemodynamic and electrical state in normal sinus rhythm after chronic dual-chamber pacing for relief of left ventricular outflow obstruction in hypertrophic cardiomyopathy

Dual-chamber (DDD) pacing relieves left ventricular (LV) outflow tract obstruction in patients with hypertrophic cardiomyopathy. The reduction in LV outflow gradient persists in some patients after cessation of pacing. Twelve-lead and signal-averaged electrocardiograms were obtained before and after 12 weeks of DDD pacing in 18 patients with obstructive hypertrophic cardiomyopathy to determine whether the altered hemodynamic state after chronic pacing is accompanied by electrical changes. Hemodynamic studies were performed at baseline and at follow-up. Signal-averaged electrocardiograms were obtained using a Corazonix Predictor and bidirectional filters at 25 Hz to a noise level of <0.5 μV. At follow-up, LV outflow tract gradients were reduced significantly during DDD pacing and with cessation of pacing in sinus rhythm by 56 ± 10 and 47 ± 10 mm Hg, respectively (p < 0.001). There was no simple relation between changes in LV outflow tract gradient and in the electrocardiogram. For example, amplitude of the R wave in V 5,6 was reduced by ≥0.5 mv in 4 patients, unchanged in 12 and increased in 2. Similarly, the S wave in leads V 1,2 was reduced in 7 patients, unchanged in 7 and increased in 4. The T wave became more negative (≥0.1 mv) in leads II, III, aVF and V 5,6 in 13 patients and more positive in leads I and aVL in 12. The QRS was also altered by signal-averaged electrocardiographic criteria; duration of the total QRS and root-meansquare voltage of the QRS of the filtered Y axis increased (106 ± 12 to 112 ± 13 ms [p = 0.036] and 170 ± 82 to 195 ± 102 μV [p = 0.059], respectively). In conclusion, chronic DDD pacing significantly reduces obstruction to LV outflow, and after discontinuation of chronic DDD pacing, there is evidence of altered mechanical as well as electrical myocardial state.

Transesophageal Doppler echocardiography in obstructive hypertrophic cardiomyopathy: Clarification of pathophysiology and importance in intraoperative decision making

To better understand the pathophysiology of obstruction of left ventricular outflow in hypertrophic cardiomyopathy and to determine the value of intraoperative transesophageal Doppler echocardiography in decision making, 32 consecutive patients undergoing ventriculomyectomy were assessed. The mean preoperative left ventricular outflow gradient was 83 ± 39 mm Hg and the mean basal septal width was 24 ± 6 mm. Compared with transesophageal findings in 10 normal control subjects, the mitral leaflets were longer and the coaptation point was abnormal in the patients with obstructive hypertrophic cardiomyopathy (anterior and posterior leaflet lengths in the patients were 31 ± 4 vs. 22 ± 3 mm in the control group [p < 0.00001] and 20 ± 2 vs. 15 ± 3 mm in the control group [p < 0.00001]). The coaptation point in the patient group was in the body of the leaflets at a mean of 9 ± 2 mm from the anterior leaflet tip, whereas it was at or within 3 mm of the leaflet tip in the normal group.During early systole, the distal third to half of the anterior mitral leaflet angled sharply anteriorly and superiorly (systolic anterior motion), resulting in leaflet-septal contact and incomplete mitral leaflet coaptation in mid-systole. This caused the formation of a funnel, composed of the distal parts of both leaflets, that allowed a jet of posteriorly directed mitral regurgitation to occur in mid- and late systole. The sequence of events in systole was eject/obstruct/leak.Transesophageal echocardiography was also helpful in planning the extent of the resection, assessing the immediate result and excluding important complications. In successful cases, the post-myectomy study showed 1) a dramatic thinning of the septum, with widening of the left ventricular outflow tract to a width similar to that in the normal subjects, 2) resolution of systolic anterior motion and the left ventricular outflow tract color mosaic, and marked reduction or abolition of mitral regurgitation despite persistence of abnormal mitral leaflet length and an abnormal mitral leaflet coaptation point. The routine use of transesophageal echocardiography in patients undergoing surgical myectomy for the treatment of obstructive hypertrophic cardiomyopathy is recommended.

Left ventricular outflow tract obstruction in patients with hypertrophic cardiomyopathy: Increase in gradient after exercise

To define alterations in the magnitude of the left ventricular outflow tract gradient during supine exercise, 10 patients with hypertrophic obstructive cardiomyopathy were studied under basal conditions and during exercise and recovery with simultaneous invasive hemodynamic measurements, particularly of the peak to peak systolic pressure gradient across the left ventricular outflow tract. Basal outflow pressure gradient ranged from 0 to 89 mm Hg (average 37.4 +/- 9.6). No increase was observed during 5 min of exercise (average 29.6 +/- 10 mm Hg, range 0 to 91; p = NS), even though arterial blood pressure, heart rate and cardiac index increased significantly in association with a decrease in peripheral vascular resistance. However, a rapid and highly significant increase in left ventricular outflow gradient occurred after exercise was completed (average 83.5 +/- 11.4 mm Hg, range 10 to 130; p less than 0.001), while arterial blood pressure, heart rate and cardiac index closely approached basal levels and total peripheral vascular resistance increased. In contrast to previous assumptions regarding the behavior of the outflow gradient in hypertrophic cardiomyopathy, obstruction to left ventricular outflow increases after rather than during supine exercise. Rapid changes in preload during recovery represent the most likely explanation for the postexercise development of outflow obstruction. New considerations regarding the mechanisms of sudden cardiac death and the therapeutic approach in patients with hypertrophic cardiomyopathy may result from this pathophysiologic observation.

Intermediate-term survival and functional results after arterial repair for transposition of the great arteries

An assessment of late morbidity and mortality is essential before arterial repair can be considered truly corrective for patients with transposition of the great arteries. We describe the early and intermediate-term results in 126 patients who underwent arterial repair. Operation was performed at a median age of 6 days, with 76 patients operated on within the first 7 days of life. Coronary artery anatomy differed from the usual arrangement in 37 patients. Simultaneous procedures included ventricular septal defect closure (35) and repair of interrupted aortic arch (2) or coarctation (5). Hospital mortality was seven of 126 (5.5%), with three deaths among the most recent 100 patients (3%). There were one late, noncardiac death and one late death after reoperation. Reoperation for pulmonary artery stenosis was required in 10 of the first 63 patients (16%), all of whom underwent pulmonary artery reconstruction with separate patches for closure of the coronary excision sites. Of the last 63 patients, all of whom underwent pulmonary artery reconstruction with a single pantaloon-shaped pericardial patch, one (2%) required reoperation for pulmonary artery stenosis. Doppler flow studies and echocardiography performed in 115 of 119 surviving patients at a mean of 12 months after repair demonstrated normal left ventricular function, minimal left ventricular outflow gradients, and no more than trivial aortic regurgitation. Peak gradient across the right ventricular outflow tract was 19 +/- 3 mm Hg in patients with separate pulmonary artery patches and 5 +/- 2 mm Hg in those with a single pantaloon patch (p = 0.0001). Follow-up is 96% complete from 1 month to 8 years after operation (mean 2.5 years). The actuarial survival rate at 5 years, including operative mortality, was 92%. All patients are in sinus rhythm, and none requires antiarrhythmic medications. These data suggest that pulmonary artery reconstruction with a single pantaloon patch may be associated with a decreased requirement for reoperation. Intermediate-term survival and functional results are excellent after arterial repair for transposition of the great arteries.