Posterior Left Ventricular Free Wall Research Articles

Thoracoscopic Trans-mitral Septal Myectomy for Hypertrophic Obstructive Cardiomyopathy in the Elderly

BackgroundThe thoracoscopic trans-mitral approach can not only facilitate exposure of the ventricular septum, mitral valve, and subvalvular apparatus, it also enables the surgeons to perform concomitant mitral valve intervention. This study aimed to determine the safety and efficacy of thoracoscopic trans-mitral septal myectomy in elderly patients with hypertrophic obstructive cardiomyopathy (HOCM).MethodsWe reviewed the demographic to clinical characteristics and outcomes of patients who underwent thoracoscopic trans-mitral septal myectomy in our center between April 2019 and April 2021. The population was divided into a younger group (<60 years) and an elderly group (≥60 years).ResultsThere were 46 and 20 patients in the younger and elderly groups, respectively. The majority of patients in the elderly group were female (39.1 vs. 80.0%, P < 0.01). Patients in the elderly group were more likely to be in New York Heart Association Class IV (2.2 vs. 80.0%, P < 0.01). The European System for Cardiac Operation Risk Evaluation II predicted mortality rates were significantly higher (3.97 ± 1.81 vs. 1.62 ± 0.86%, P < 0.01) in the elderly group. In the elderly group, a patient converted to median sternotomy due to left ventricular posterior free wall rupture following septal myectomy and mitral bioprosthetic valve replacement. The patient then underwent double-patch sandwich repair for rupture and mitral mechanical valve replacement and was eventually discharged. All patients in the elderly group were discharged, while one in the younger group died. No patient in the elderly group required permanent pacemaker implantation vs. one in the younger group. Patients in the elderly group were more likely to spend more time in the intensive care unit than those in the younger group (5.44 ± 5.80 days vs. 3.07 ± 2.72, P < 0.05). However, there was no significant intergroup difference in in-hospital mortality or complications. Importantly, the left ventricular outflow tract pressure gradient was significantly decreased from 96.15 ± 32.89 mmHg to 8.2 ± 3.42 mmHg with no residual obstruction in the elderly group. The interventricular septal thickness was significantly decreased from 19.73 ± 3.14 mm to 11.30 ± 2.23 mm. Postoperative mitral regurgitation severity was significantly improved in the elderly group.ConclusionThis study demonstrated that thoracoscopic trans-mitral septal myectomy is a feasible option for selected elderly patients with satisfactory outcomes similar to those of young patients.

Reference Values and Repeatability of B-Mode and M-Mode Echocardiographic Parameters in Healthy Donkey (Equus asinus)—The Guide to Assess Healthy Heart

Donkey (Equus asinus), the cheapest form of agricultural power in Egypt, is used principally as draught or pack animals and may also be ridden, or used for threshing, raising water, milling, and other work. The aim of the present study was to provide B-mode and M-mode echocardiographic reference ranges from a sample of population of donkeys (E. asinus) based on the probability theory and statistics. In the present study, B-mode and 2-dimensional guided M-mode echocardiography were performed on 44 clinically healthy donkeys (E. asinus) (22 males and 22 females), without any neither clinical nor echocardiographic evidence of cardiovascular diseases, aged 2–25 year old, and weighed 150–350 kg. The echocardiographic dimensions, including interventricular septum thickness at end diastole, interventricular septum thickness at end systole, left ventricular internal diameter at end diastole, left ventricular internal diameter at end systole, left ventricular posterior wall thickness at end diastole, and left ventricular posterior wall thickness at end systole were assessed. The cardiac function indices, including end diastolic volume, end systolic volume, stroke volume, ejection fraction, and fractional shortening were also measured. B-mode and guided M-mode echocardiographic examination of healthy donkeys revealed that both the interventricular septum thickness and the left ventricular posterior free wall were greater during systole than diastole. However, the left ventricular dimension during diastole was greater than systole. Furthermore, the recorded data of cardiac function indices, including end diastolic volume, end systolic volume, stroke volume, ejection fraction, and fractional shortening using B-mode echocardiography were closer to those recorded by guided M-mode echocardiography. To our knowledge, this is the first Egyptian study to report the echocardiographic reference ranges of donkeys (E. asinus) based on the probability theory and statistics, the coefficient of variation. The results of the present study can be used as standard and reference values for further echocardiographic studies in donkeys and represent a step in the identification, interpretation, and evaluation of cardiovascular disorders in such animals.

Interventricular septal hematoma complicating placement of a ventricular assist device in an infant and support with bi-atrial cannulation.

Interventricular septal hematoma complicating placement of a ventricular assist device in an infant and support with bi-atrial cannulation.

Inferior ischemic ventricular septal defect: Atypical triple pericardial patch implantation technique

We presented the successful management of an inferior ischemic ventricular septal defect (VSD) associated with posterior left ventricular free wall rupture, following the occlusion of a dominant right coronary artery (RCA). The defect was approached through a longitudinal incision over the infarcted area, 1 cm parallel to the posterior descending coronary artery (PDA). The VSD was repaired using three pericardial patches and GRF (gelatin-resorcinol-formaldehyde) glue. ECMO and IABP were used in order to decrease the LV wall tension, the risk of recurrence of VSD and the risk of free wall rupture. The postoperative echocardiogram documented good biventricular geometry with a left ventricle ejection fraction (LVEF) of 55%. No left-to-right shunt was seen

Ultrastructural myocardial changes in seven cats with spontaneous hypertrophic cardiomyopathy

ObjectivesHypertrophic cardiomyopathy (HCM) is the most common heart disease in cats and shares clinical and pathological characteristics with human HCM. Little is known about the pathogenic mechanisms underlying development of spontaneous feline HCM. AnimalsThe study population consisted of seven cats diagnosed with HCM and eight age-matched cats with no evidence of cardiac disease. MethodsFresh myocardial biopsies taken from the middle of the left ventricular posterior free wall were obtained and examined with transmission electron microscopy. ResultsElectron microscopic examination showed ultrastructural aberrations of the myocardial cytoarchitecture and of the interstitium in the seven cats with HCM. In the most severely affected cats the myofibrils were disorganized and subsarcolemmal mitochondria were depleted. In control cats, contraction band artifacts were commonly seen. ConclusionsIn this preliminary study we show that ultrastructural changes of the myocardium in seven cats with HCM involve the cytoskeleton and mitochondria. We suggest that our findings are important for future research aiming at elucidating the pathogenic mechanisms underlying the phenotypic expression of feline HCM.The results of this study prompt for a larger scale study, including quantitative measurements of mitochondrial distribution and cytoskeletal derangements in feline HCM.

Hypertrophic Cardiomyopathy in Preterm Infants Treated With Methylprednisolone for Bronchopulmonary Dysplasia

To the Editor.Glucocorticoids, and in particular dexamethasone, have been used extensively in the prophylaxis and treatment of bronchopulmonary dysplasia in preterm infants. In fact, extensive studies have proven that dexamethasone, given early (<96 hours of life)1 or moderately early (7–14 days of life),2 is effective in reducing the combined frequency of bronchopulmonary dysplasia and mortality. Unfortunately, such effect is associated with numerous adverse effects such as hyperglycemia, hypertension, hypertrophic cardiomyopathy, psychomotor development delay, and cerebral palsy. In particular, the relative risk for the development of hypertrophic cardiomyopathy is 4.39 (95% confidence interval: 1.40–13.37) in infants who received early dexamethasone treatment1 and 14.3 (95% confidence interval: 1.20–67.69) in infants who received moderately early dexamethasone treatment.2Therefore, the American Academy of Pediatrics advised against the treatment with dexamethasone of infants with birth weights <1500 g (very low birth weight [VLBW]), recommended to limit its use to exceptional clinical circumstances and carefully designed randomized, controlled trials, and suggested the opportunity of following clinical trials investigating the use of alternative antiinflammatory corticosteroids.3 Accordingly, we started to treat VLBW preterm infants on maximal ventilatory and oxygen support (median arterial/alveolar oxygen ratio: 0.09; range: 0.07–0.11) with a 12-day tapering course of methylprednisolone given intravenously every 6 hours (0.6, 0.4, 0.2, 0.1 mg/kg per dose for 3 days each).4 From January 1, 2003, to June 30, 2005, we treated with methylprednisolone 10 preterm infants (median gestational age: 24 weeks [range: 23–26 weeks]; median birth weight: 620 g [range: 430–730 g]) affected by respiratory distress syndrome and mechanically ventilated at the median postnatal age of 16.5 days (range: 9–44 days). These patients did not present adverse effects from steroid treatment other than hyperglycemia (1 case) and hypertrophic cardiomyopathy. In fact, echocardiographic study showed in 4 patients (40%) a thickening of the intraventricular septum (reference value: 1.8–4.5 mm) that ranged between 5 and 7 mm (median value: 6 mm) and was associated in 2 cases with a mild thickening of the posterior left ventricular free wall, without an impairment of left ventricular outflow. No pharmacologic therapy was necessary for these patients. However, methylprednisolone was discontinued immediately (median treatment duration: 8.5 days; range 7–10 days), and the pathologic echocardiographic findings disappeared after a median period of 26 days (range: 22–32 days). Among the methylprednisolone-treated infants, 6 (60%) survived, including 3 infants who developed hypertrophic cardiomyopathy.We compared the occurrence of hypertrophic cardiomyopathy with that found in preterm VLBW infants affected by respiratory distress syndrome who did not receive steroid treatment (n = 20) or who were treated with dexamethasone. These infants were randomly selected between those who were born immediately before of after infants treated with methylprednisolone. We found that hypertrophic cardiomyopathy was strongly more frequent in methylprednisolone-treated versus untreated infants (40% vs 0%; P < .0001, calculated by using Fisher's Exact Test) but was similar in methylprednisolone- versus dexamethasone-treated infants (40% vs 20%; P < .3149).Methylprednisolone may represent a possible alternative to dexamethasone in preventing or treating bronchopulmonary dysplasia. However, we found a strong association between the treatment with methylprednisolone and the development of hypertrophic cardiomyopathy in VLBW preterm infants at risk for bronchopulmonary dysplasia.The mechanisms of cardiac hypertrophy resulting from corticosteroid therapy remain unclear, as do those of neurodevelopment injury associated with dexamethasone treatment. Moreover, actual knowledge does not permit evaluating the eventual pathophysiological correlation between cardiac and brain damage. Thus, it cannot be excluded that, similar to dexamethasone, methylprednisolone can exert detrimental adverse effects on both the heart and central nervous system in preterm infants.For these reasons we suggest that, in planning future clinical trials to investigate the use of corticosteroids in preterm infants, those making the choice of drug take into account all of its reported adverse effects. From this point of view, methylprednisolone and dexamethasone similarly induce the occurrence of hypertrophic cardiomyopathy in preterm infants with respiratory distress syndrome.

The heart in neurofibromatosis type 1: An echocardiographic study

Background Comprehensive data are unavailable for cardiac abnormalities in patients with neurofibromatosis type 1 (NF1). The goal of this study was to evaluate the prevalence of cardiovascular abnormalities with echocardiography with color Doppler scan (ECHO) in a large, consecutive series of patients with NF1. Methods We studied 48 patients with NF1 (mean age, 10 years). Thirty healthy subjects comparable for age and sex served as the control group. All ECHO studies were performed by the same cardiologist and reviewed by a second cardiologist blinded to the physical findings of the subjects. Results Cardiac abnormalities were found in 13 of the 48 young patients (27%). A secundum atrial septal defect with a left to right shunt was found in 2 children. ECHO evidence of mild left pulmonary artery stenosis was found in 1 participant. A moderate coarctation of the thoracic aorta was found in 1 patient. ECHO criteria for mitral valve prolapse and evidence of trivial mitral regurgitation with myxomatous mitral valve was present in 1 case. Mild mitral regurgitation was found in 2 patients. A regurgitant mild flow signal was detected from the aortic valve in 2 subjects. Atrial septal aneurysm was found in 2 patients without patent foramen ovale. Two patients had septal to posterior left ventricular free wall ratio greater than 1.5, suggesting hypertrophic cardiomyopathy. Conclusion This is the first attempt to evaluate the prevalence of cardiovascular abnormalities in patients with NF1 with ECHO. The study's most striking finding is the high prevalence of cardiovascular abnormalities. Congenital lesions have potential long-term hemodynamic consequences that justify an early diagnosis. Thus, a cardiologic assessment at regular intervals, including ECHO study, is mandatory for patients with NF1. (Am Heart J 2002;143:883-8.)

Entire septal patch technique for postinfarction ventricular septal rupture

Postinfarction ventricular septal rupture is still a surgically challenging situation with high operative mortality. We report a case of ventricular septal rupture in a 75-year-old woman successfully treated with our newly devised technique, in which a pliable large septal path is fixed with transmural sutures placed in posterior left ventricular free wall and anterior ventriculotomy closing sutures, thus covering the septal wall almost entirely. Our method may simplify the operation and reduce the risk of residual leakage.

Operative treatment of hypertrophic obstructive cardiomyopathy and aortic valve disease in infants.

The indications for operative intervention for symptomatic hypertrophic obstructive cardiomyopathy (HOCM) in infancy and childhood are not well defined because of the rarity of the lesion. The traditional surgical procedure consists of septal myectomy. In an attempt to further improve the outcome of HOCM associated with concentric left ventricular hypertrophy and aortic valve disease in infancy, we have combined resection of the left ventricular septum and free wall with a Ross-Konno procedure. Three infants (aged 3, 4, and 10 months) with HOCM (left ventricular aortic gradients of 75, 95, and 110 mmHg), associated concentric left ventricular hypertrophy, and valvar aortic stenosis (n = 1) or combined valvar aortic stenosis and regurgitation (n = 2) underwent extensive resection of fibroelastosis and subendocardial myocardium of the left ventricular septum and free wall in combination with a Ross-Konno operation. All three patients had marked systolic anterior motion of the mitral valve. The length of the incision into the ventricular septum was 1.8, 2.0, and 2.3 cm. In all three patients this procedure resulted in a marked reduction of width of the left ventricular septum (median 9 mm vs 14 mm preoperatively) and the left ventricular posterior free wall (median 8 mm vs 12 mm preoperatively) and an almost twofold increase of the left ventricular end-diastolic volume (median 13.5 cm3 vs 7.0 cm3 preoperatively). The neo-aortic valve functioned normally. Systolic anterior motion of the anterior leaflet of the mitral valve had completely resolved in two patients and had markedly regressed in the remaining patient. At follow-up of 15, 17, and 26 months, two patients had absence of a left ventricular outflow tract gradient and the third patient had a residual sub-valvar gradient of 15 mmHg. The reported procedure may be a valuable technique in severe forms of hypertrophic cardiomyopathy associated with aortic valve disease. The operation results in enlargement of the left ventricular stroke volume and improvement of the left ventricular diastolic function, restores aortic valve anatomy and function, and abolishes or decreases systolic anterior motion of the mitral valve.

Ross-Konno Operation With Resection of Endocardial Fibroelastosis for Critical Aortic Stenosis With Borderline-Sized Left Ventricle in Neonates

Background. Critical aortic stenosis with severe concentric left ventricular hypertrophy and endocardial fibroelastosis has a substantial mortality rate when the conventional therapeutic strategy, ie, open surgical or balloon valvuloplasty, is applied. During the last decade, univentricular repair (Norwood operation) and heart transplantation have evolved as the only viable therapeutic options. An alternative in patients with borderline hypoplastic left heart syndrome consists of performance of a Ross-Konno operation with surgical enlargement of the left ventricular cavity, a procedure that has the advantage of achieving a two-ventricle repair. Methods. Two neonates and 2 young infants with critical aortic stenosis, concentric left ventricular hypertrophy, and severe endocardial fibroelastosis, with echocardiographically documented antegrade flow in the ascending aorta, underwent a Ross-Konno operation combined with extensive endocardial and myocardial resection of the left ventricular septum and free wall. The incision in the ventricular septum was closed with a wide cuff of infundibular muscle that was harvested in continuity with the pulmonary autograft. Results. In all 4 patients, the operation resulted in normal aortic valve function, marked reductions of width of the left ventricular septum (median, 6.5 mm, versus 11 mm preoperatively) and the left ventricular posterior free wall (median, 8.5 mm, versus 15.5 mm preoperatively), and enlargement of the left ventricular end-diastolic volume (median, 12.5 cm 3, versus 6.5 cm 3 preoperatively). Three patients had an uneventful recovery, with gradual improvement of left ventricular diastolic and systolic function during the first postoperative week; 1 neonate with associated mitral regurgitation died of left ventricular failure. Conclusions. The Ross-Konno procedure with resection of endocardial fibroelastosis may be a valuable adjunct for achieving a two-ventricle repair in borderline hypoplastic left heart syndrome. The operation results in enlargement of the left ventricular stroke volume and improvement of left ventricular diastolic function; in addition, resection of endocardial fibroelastosis relieves the mechanical impairment of myocardial function and therefore may promote the potential for left ventricular growth. (Ann Thorac Surg 1997;63:112–6)

Changes in myocardial echo amplitude during reversible ischaemia in humans.

This study investigated the changes in regional myocardial ultrasonic backscatter, measured as myocardial echo amplitude, that occur during reversible myocardial ischaemia in humans. Left anterior descending coronary angioplasty was used to produce reversible myocardial ischaemia in human subjects. Regional myocardial echo amplitude was studied in the interventricular septum and left ventricular posterior free wall before, during, and after coronary occlusion with the angioplasty balloon. Wall motion analysis of the left ventricle was performed from simultaneous cross sectional echocardiographic imaging. Patients were studied prospectively. Six patients (mean age 56 (SD 11), range 46 to 69 years) with single vessel, left anterior descending coronary artery stenoses, were investigated during elective coronary angioplasty. A total of 11 balloon inflations were studied. All patient studies were performed at Harefield Hospital. Echo amplitude analysis was performed at the Royal Brompton Hospital. Angioplasty was performed by the usual procedure at Harefield Hospital for elective coronary angioplasty. All routine medication including beta blockers and calcium antagonists were continued. Inflation pressures were up to 12 atm (1212 kPa) and mean inflation time ranged from 30 to 120 (86 (31)) s. In four studies the first inflation was examined, in three the second, in two the third, and in one each the fourth and fifth inflations. Echo amplitude and cross sectional echo-cardiographic studies were recorded with a 3.5 MHz Advanced Technology Laboratories (ATL) (720A/8736 series) mechanical sector scanner and an ATL Mark III (860-1 series) echocardiograph system with 45 dB logarithmic grey scale compression. Regional echo amplitude was examined in four regions of the left ventricle--namely, the basal and mid-septum, and basal and mid-posterior wall. Consecutive end diastolic and end systolic frames were analysed and cyclic variation was determined as the difference between the level of echo amplitude at end diastole and at end systole. Measurements were made before balloon inflation, at peak inflation, and after balloon deflation. Regional wall motion and systolic wall thickening were analysed qualitatively. Before balloon inflation, cyclic variation in echo amplitude was noted in all regions (basal septum, 2.4 (SD 1.1) dB; mid-septum, 2.5 (1.1) dB; basal posterior wall, 3.3 (2.1) dB; mid-posterior wall, 3.9 (1.6) dB). During balloon inflation there was a significant fall in cyclic variation to 0.4 (0.9) dB (p < 0.0002) in the mid-septum. This was predominantly owing to an increase in end systolic echo amplitude from 5.4 (2.0) dB to 9.3 (1.9) dB (p < or = 0.01). This was associated with the development of severe hypokinesis or akinesis in the mid-septum. No significant changes in echo amplitude occurred in the three other regions examined. Changes were completely reversed after balloon deflation. These results suggest a causal relation between occlusion of the supplying coronary artery and blunting of myocardial echo amplitude cyclic variation. It is suggested that balloon occlusion produced myocardial ischaemia. The resultant impairment of myocardial contraction then caused a blunting of cyclic variation in echo amplitude. The results of this study provide further data about the ability of quantitative studies of ultrasonic backscatter to identify alterations in the myocardium during injury.

Progressive cardiac dysfunction with repeated pacing-induced ischemia: protection by AICA-riboside

The effects of repeated episodes of demand-induced ischemia on regional myocardial wall thickening, endocardial electrogram, and regional myocardial blood flow are not well delineated. We studied the cumulative effects of six periods of pacing-induced ischemia in 35 chloralose-anesthetized dogs with circumflex coronary stenosis. Repetitive ischemia of the posterior left ventricular free wall was induced with six 5-min pacing periods separated by 15-min recovery periods. The three groups of dogs studied were 1) saline control, 2) the purine precursor 5-aminoimidazole 4-carboxamide riboside (AICA-r), and 3) nitroglycerin (NTG). During the initial pacing period (before treatment), thickening of the posterior wall declined in the saline group (43 +/- 5% of control), the AICA-r group (47 +/- 8% of control), and the NTG group (55 +/- 3% of control), associated with endocardial S-T segment elevation and a decrease in subendocardial blood flow. Wall thickening continued to decrease in each group with each successive pacing episode. However, during the sixth pacing period wall thickening was significantly (P less than 0.05) less in the saline group (2 +/- 5% of control) than in the AICA-r (31 +/- 7% of control) or NTG (61 +/- 7% of control) group. The progressive decline in wall thickening was accompanied by a further decrease in subendocardial blood flow and a rise in S-T segment in the saline group but not in the AICA-r or NTG group (P less than 0.05). These results demonstrate that sequential periods of ischemia and reperfusion cause a progressive decline in regional wall motion, coincident with a progressive decrease in subendocardial blood flow.(ABSTRACT TRUNCATED AT 250 WORDS)

Hypertrophic cardiomyopathy characterized by marked hypertrophy of the posterior left ventricular free wall: Significance and clinical implications

This report describes a subgroup of 17 patients with hypertrophic cardiomyopathy and an unusual and distinctive pattern of left ventricular hypertrophy characterized on echocardiography by marked thickening of the posterior left ventricular free wall and virtually normal or only modestly increased ventricular septal thickness. This distribution of hypertrophy often created a distinctive pattern of “inverted” asymmetry of the posterior wall relative to the septum. The thickness of the posterior wall was 20 to 42 mm (mean 25), while that of the basal ventricular septum was only 12 to 24 mm (mean 17). The left ventricular outflow tract was narrowed because of anterior displacement of the mitral valve within the small left ventricular cavity. Systolic anterior motion of the mitral valve was present in 16 of the 17 patients.The patients ranged in age from 13 to 54 years (mean 31) at most recent evaluation; most (11 of 17, 65%) were severely symptomatic and had experienced important symptoms early in life (before age 40). The condition of only 4 of these 11 patients improved with medical therapy over an average follow-up period of 9 years; however, 6 of the 7 patients who had unsuccessful medical treatment and underwent operation with mitral valve replacement (5 patients) or ventricular septal myotomy-myectomy (1 patient) experienced symptomatic benefit from surgery.The subgroup of patients described in this report underscores the morphologic and clinical diversity that exists within the overall disease spectrum of hypertrophic cardiomyopathy. Characteristically, the patients were young, severely symptomatic and demonstrated evidence of outflow obstruction and an “inverted” asymmetric pattern of posterior free wall left ventricular hypertrophy. Because of their relatively modest ventricular septal hypertrophy, mitral valve replacement (rather than myotomy-myectomy) may be the operative procedure of choice in such patients with obstructive hypertrophic cardiomyopathy.

Incessant ventricular tachycardia in infancy

Two infants with incessant tachycardia uncontrolled by multiple drug treatment were thought initially to have supraventricular tachycardia. Careful examination of the 12-lead electrocardiogram suggested ventricular tachycardia, which was confirmed by electrophysiological studies. Intra-operative mapping showed that the arrhythmia arose from the posterior left ventricular free wall in one infant and at the left ventricular apex in the other. Cryoablation of these foci led to cessation of ventricular tachycardia. Myocardial biopsy showed hamartomatous involvement in the first infant and normal tissue in the other. In the first infant the incessant arrhythmia was cured but in the other it recurred 4 months later. The origin of the recurrent tachycardia was adjacent to the previously cryoablated arrhythmogenic area. This area was also cryoablated, leading to disappearance of the ventricular tachycardia. Both patients are free of arrhythmia 10 months and 3 months after their surgery. Surgically ablatable lesions are common in infants with incessant ventricular tachycardia. Early diagnosis and prompt surgical treatment usually can effect 'cure' of this potentially fatal problem in childhood.

Time course of sympathetic denervation supersensitivity in canine ventricular recovery

We studied the timing of the electrophysiological effects of sympathetic supersensitivity with chronically implanted electrodes in the anterior and posterior left ventricular free wall in 10 dogs. We produced denervation of the anterior wall in six dogs by application of phenol surrounding the anterior electrode. Drug infusions that were performed under pentobarbital sodium anesthesia included norepinephrine, isoproterenol, and methoxamine. In four controls there was no difference in response of the two sites. Presynaptic supersensitivity was manifest as early as 2 days and as late as 64 days by a parallel left shift (greater than or equal to 8.3 ms) in the norepinephrine dose to effective refractory period shortening response curve in the anterior compared with posterior left ventricle, P less than 0.01. The isoproterenol dose-response curve was also shifted to the left by 5.6 ms (P less than 0.01) but was manifest only after 10 days and only until 28 days from the denervation procedure. Local repolarization in the denervated areas shortened more than the innervated areas with both drugs. The methoxamine dose-response curve was flat, and the anterior-denervated area was not different than the posterior-innervated area. We conclude that recovery properties in ventricular muscle demonstrate evidence of supersensitivity, which is neurotransmitter and beta- but not alpha-receptor specific.

Operative Treatment of Hypertrophic Obstructive Cardiomyopathy and Aortic Valve Disease in Infants

Abstract Background: The indications for operative intervention for symptomatic hypertrophic obstructive cardiomyopathy (HOCM) in infancy and childhood are not well defined because of the rarity of the lesion. The traditional surgical procedure consists of septal myectomy. In an attempt to further improve the outcome of HOCM associated with concentric left ventricular hypertrophy and aortic valve disease in infancy, we have combined resection of the left ventricular septum and free wall with a Ross‐Konno procedure. Methods: Three infants (aged 3, 4, and 10 months) with HOCM (left ventricular aortic gradients of 75, 95, and 110 mmHg), associated concentric left ventricular hypertrophy, and valvar aortic stenosis (n = 1) or combined valvar aortic stenosis and regurgitation (n = 2) underwent extensive resection of fibroelastosis and subendocardial myocardium of the left ventricular septum and free wall in combination with a Ross‐Konno operation. All three patients had marked systolic anterior motion of the mitral valve. The length of the incision into the ventricular septum was 1.8, 2.0, and 2.3 cm. Results: In all three patients this procedure resulted in a marked reduction of width of the left ventricular septum (median 9 mm vs 14 mm preoperatively) and the left ventricular posterior free wall (median 8 mm vs 12 mm preoperatively) and an almost twofold increase of the left ventricular end‐diastolic volume (median 13.5 cm3 vs 7.0 cm3 preoperatively). The neo‐aortic valve functioned normally. Systolic anterior motion of the anterior leaflet of the mitral valve had completely resolved in two patients and had markedly regressed in the remaining patient. At follow‐up of 15, 17, and 26 months, two patients had absence of a left ventricular outflow tract gradient and the third patient had a residual sub‐valvar gradient of 15 mmHg. Conclusions: The reported procedure may be a valuable technique in severe forms of hypertrophic cardiomyopathy associated with aortic valve disease. The operation results in enlargement of the left ventricular stroke volume and improvement of the left ventricular diastolic function, restores aortic valve anatomy and function, and abolishes or decreases systolic anterior motion of the mitral valve. (J Card Surg 1999:14:273–278)

Efferent vagal innervation of canine ventricle

The route efferent vagal fibers travel to reach the left ventricle is not clear and was the subject of this investigation. We measured left ventricular and septal effective refractory period (ERP) changes during vagal stimulation and a constant infusion of norepinephrine, before and after phenol was applied at selected sites of the heart to interrupt efferent vagal fibers that may be traveling in that area. Phenol applied to the atrioventricular (AV) groove between the origin of the right coronary artery anteriorly to the posterior descending branch of the circumflex coronary artery completely eliminated vagal-induced prolongation of ERP in the anterior and posterior left ventricular free wall and reduced, but did not eliminate, ERP prolongation in the septum. A large (3-cm radius) epicardial circle of phenol prevented vagal-induced ERP prolongation within the circle in all dogs, while a small (1-cm radius) epicardial circle of phenol failed to prevent vagal-induced ERP changes within the circle in any dog. An intermediate (2-cm radius) circle eliminated vagal effects on ERP in 13 of 18 dogs. Arcs of phenol, to duplicate the upper portion of the circle, applied sequentially from apex to base eliminated efferent vagal effects only when painted near or at the AV groove. We conclude that the majority of efferent vagal fibers enroute to innervate the anterior and posterior left ventricular epicardium cross the AV groove within 0.25-0.5 mm (depth of phenol destruction) of the epicardial surface.(ABSTRACT TRUNCATED AT 250 WORDS)

Phenol topically applied to canine left ventricular epicardium interrupts sympathetic but not vagal afferents.

The intracardiac pathways carrying the cardiovascular reflex responses mediated by cardiac sympathetic and vagal afferent fibers were examined in this study. We investigated the response to epicardial applications of bradykinin (5 micrograms) and nicotine (50 micrograms) before and after regional epicardial applications of 85% phenol in chloralose anesthetized open-chest dogs. Bradykinin stimulated sympathetic afferents, while nicotine stimulated vagal afferents. Topical applications of phenol were used to interrupt these pathways. Before phenol encircling, bradykinin significantly increased--whereas nicotine significantly decreased--mean arterial blood pressure when applied at the same sites. After phenol, nicotine applied to all sites within and outside the phenol circle continued to decrease mean arterial pressure, whereas bradykinin applied to sites within the circle no longer increased mean arterial pressure. Removal of aortic and carotid baroreceptors did not significantly affect these responses. Painting horizontal stripes of phenol on the anterior and posterior left ventricular free wall basal to the site of bradykinin application eliminated the elevation in mean arterial pressure produced by bradykinin. Reapplication of bradykinin basal to the stripe restored its response. Phenol stripes eliminated the nicotine vasodepressor response only when the stripe was painted in the atrioventricular groove. When bradykinin and nicotine were injected via a nonocclusive intracoronary catheter, both drugs elicited an early depressor response (interrupted by vagotomy) and, in some animals a late pressor response (interrupted by stellectomy). Epicardial phenol encircling the flow distribution of the cannulated coronary artery interrupted most or all of the sympathetic afferents mediating pressor responses to bradykinin or nicotine, while leaving the depressor responses intact. The depressor responses were eliminated by applying phenol to the atrioventricular groove or by transecting the cervical vagi. These data suggest that sympathetic afferent fibers travel in the superficial subepicardium in an apex-to-base direction. Vagal afferent fibers travel deeper in the myocardium until they approach the atrioventricular groove, where they ascend to the superficial subepicardium.

Serial two-dimensional echocardiography in Duchenne muscular dystrophy.

Patients with Duchenne muscular dystrophy (DMD) are known to have progressive epicardial fibrosis of the free wall of the left ventricle, but standard noninvasive M-mode echocardiographic tests of left ventricular function are relatively insensitive detectors of this cardiomyopathy. We therefore used two-dimensional echocardiography to record three short axis levels of the left ventricle in 13 Duchenne patients. Serial studies were separated by 2 years for most patients. The two-dimensional echocardiographic technique allows qualitative evaluation of segmental contraction of the left ventricle. Four general principles were found during this study: (1) Obvious contraction abnormalities of the left ventricle were present in most patients with DMD. (2) In most patients, the contraction deficit was first noted in the left ventricular posterior free wall behind the mitral valve. (3) Once a contraction deficit was observed, the area of abnormal contraction progressed inferiorly to include additional areas of the left ventricular posterior free wall. (4) Standard M-mode left ventricular function techniques were unreliable for detecting individuals with segmental contraction abnormalities.

Improved results of surgical management of postinfarction ventricular septal rupture.

Fifty-five patients had surgical repair of postinfarction ventricular septal rupture in Massachusetts General Hospital from 1968 through 1981. In patients operated more than three weeks after infarction, hospital survival has been 93% (14/15). Before 1975 in patients operated less than three weeks after infarction, hospital survival was 41% (7/17). In this same era patents operated for septal rupture with cardiogenic shock present before operation had a hospital survival rate of only 27% (3/11). Before 1975 patients with cardiogenic shock were supported with intra-aortic balloon pumping (IABP) and vasopressors, and operation deferred pending hemodynamic stabilization. Before 1975 patients with anterior septal rupture had a hospital survival rate of 64% (9/14), while patients with posterior septal rupture had a hospital survival rate of only 38% (5/13). This difference in survival according to the location of septal rupture occurred despite comparable numbers of patients in each group requiring early operation, as well as incidence of cardiogenic shock. Since January 1, 1975 patients operated less than three weeks after infarction have had an overall hospital survival rate of 70% (16/23). Of the 10 most recent patients operated early, nine are survivors. In patients with anterior defects 85% (11/13) survived, while in patients with posterior defects 67% survived (10/15). In patients operated with cardiogenic shock present before operation, survival has been 67% (10/15). Changes in management leading to improved results include (1) immediate operation for patients with cardiogenic shock, (2) cold cardioplegic protection of the myocardium, and (3) prosthetic replacement of posterior left ventricular free wall defect, after infarctectomy and septal repair, in patients with posterior septal rupture.