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Biomedical subjects

H Rakowski

Publications and source records attributed to H Rakowski.

At least 37 records · Page 2Linked to original sources
PubMed1998

Hemodynamics and left ventricular mass regression following implantation of the Toronto SPV stentless porcine valve.

Stentless tissue valves may provide more favorable hemodynamics than conventional stented valves. Hemodynamic findings from a large multicenter trial have not been previously reported. The present report describes the hemodynamic findings from a multinational, multicenter study after implantation of the Toronto SPV valve. A total of 577 patients underwent aortic valve replacement with the Toronto SPV valve at 12 sites in 3 countries. Echocardiograms were recorded in the early postoperative period, 3 to 6 months after surgery, 1 year after surgery, and yearly thereafter, with follow-up to 3 years. Gradients decreased and effective orifice area increased in the months after surgery. One year after surgery, mean gradient for valve sizes 20 to 22, 23, 25, 27, and 29 mm was 7.3 +/- 4.4, 7.4 +/- 4.5, 6.1 +/- 3.3, 4.9 +/- 2.4, and 4.0 +/- 2.1 mm Hg, respectively; effective orifice area was 1.3 +/- 0.7, 1.5 +/- 0.5, 1.7 +/- 0.4, 2.0 +/- 0.4, and 2.4 +/- 0.6 cm2, respectively. There was a very low prevalence of significant aortic regurgitation at all time periods. There was significant left ventricular (LV) mass regression between the early and 3- to 6-month periods and between the 3- to 6-month and 1-year postoperative periods. The Toronto SPV valve has an excellent hemodynamic profile supported by significant regression of LV hypertrophy in the year after implantation. Data through 3 years demonstrates maintenance of low gradients and freedom from significant aortic regurgitation.

Aged↗
PubMed1998

Recommendations for training in performance and interpretation of stress echocardiography. Committee on Physician Training and Education of the American Society of Echocardiography.

Stress echocardiography has emerged as a clinically useful procedure in the management of patients with ischemic heart disease and other conditions. However, the accuracy of this test relies on the ability of those who carry out the technical aspects of the test and depends critically on proper interpretation of the images. Appreciation of wall motion abnormalities is generally acknowledged as one of the most difficult skills to master in echocardiography. There is consensus that this is also one of the most difficult skills to teach. Appreciating stress-induced changes in wall motion, which sometimes are subtle, requires a significant commitment to initial training in this skill and its maintenance. This document provides recommendations for physician training in stress echocardiography.

Cardiology↗
PubMed1998

Aortic valve replacement with stentless porcine aortic valves: a ten-year experience.

BACKGROUND AND AIMS OF THE STUDY: It has been shown that although stentless porcine aortic valves have better hemodynamic features than stented porcine valves, their long-term durability remains unknown. This study was undertaken to examine the long-term clinical outcome of aortic valve replacement (AVR) with stentless porcine aortic valves. METHODS: Between 1987 and 1989, custom-made stentless valves were implanted in 29 patients (mean age 58 years), and between 1991 and 1997, the Toronto SPV was implanted in 213 patients (mean age 63 years). In addition to AVR, one-third of the patients had coronary artery bypass. All patients were followed up at annual intervals and underwent Doppler echocardiography. RESULTS: There were two operative and 11 late deaths (four cardiac, seven non-cardiac). The actuarial survival rate was 89 +/- 4% at nine years. There were two strokes and seven transient ischemic attacks; freedom from thromboembolic complications was 92 +/- 4% at nine years. Two patients developed infective endocarditis, one early and one late; freedom from prosthetic valve endocarditis was 98 +/- 1% at nine years. Freedom from primary tissue failure was 85 +/- 8% at nine years. Seven patients required repeat AVR, because of endocarditis (two) and aortic insufficiency (five); freedom from repeat AVR was 82 +/- 8% at nine years. Periodic hemodynamic assessment by echocardiography indicated that the mean systolic gradients across the valve decreased during the first year of implantation, the valve effective orifice increased, and valve competence remained stable. CONCLUSIONS: Stentless porcine aortic valves have provided excellent clinical results. These valves may suffer degenerative changes and fail at the same rate as stented porcine aortic valves but, because of their superior hemodynamic performance, they may enhance patients' survival by allowing complete regression of left ventricular hypertrophy and restoration of normal ventricular function.

Animals↗
PubMed1997

Right heart pulmonary embolism in transit: a review of therapeutic considerations.

Two patients with pulmonary emboli and right heart masses detected on echocardiography are described. One patient underwent successful surgical embolectomy and the other was successfully treated with intravenous thrombolysis. Both were alive and well at six months' follow-up. The presence of a right heart clot in the setting of pulmonary emboli carries a very high mortality rate and warrants urgent therapy, which may include anticoagulation, thrombolysis or surgical embolectomy. Because limited information is available, therapy must be individualized based on patient characteristics, clot location and local expertise. The pertinent literature is reviewed and relevant issues in decision making are discussed.

Aged↗
PubMed1997

Role of candidate modifier genes on the phenotypic expression of hypertrophy in patients with hypertrophic cardiomyopathy.

BACKGROUND: The phenotypic expression of left ventricular hypertrophy (LVH) in patients with hypertrophic cardiomyopathy (HCM) is variable. This phenotypic variability is not completely explained by the responsible mutations or other known factors. Recent data denote a role for the modifier genes and environmental factors. We studied the role of 3 potential modifier genes, i.e., angiotensinogen (AGT), angiotensin II receptor 1a (AT1a), and endothelin-1 (END1) on the phenotypic expression of LVH in patients with hypertrophic cardiomyopathy (HCM). METHODS: The study population was comprised of 108 genetically independent patients with HCM. Left ventricular mass index (LVMI) and LVH score were determined per published protocols. The genotypes of AGT (M235T, T174M, and G-6A), AT1a, and END1 were determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) or mutation-specific PCR (MS-PCR). RESULTS: Male patients had higher mean LVMI and LVH score than female patients (146.0 +/- 33.5 vs 129.4 +/- 33.6, p = 0.01 and 6.0 vs 5.0, p = 0.010, respectively). Gender accounted for 4.8% and 5.4% of the variability of LVMI and LVH score, respectively. The END1 genotypes also had a significant influence on LVH scores accounting for 2.9% of their variability (p = 0.042). The median LVH score was greater in patients with the AA and AG genotypes, as compared to patients with the GG genotype (7.0 vs 5.0, p = 0.034). Neither the AGT nor the AT1 genotypes had a significant influence on the expression of LVH. In multivariate regression analysis, END1 and gender accounted for 7.3% of the variability of the LVH score (p = 0.007). CONCLUSIONS: Our results show that gender and the END1 gene modify the phenotypic expression of hypertrophy in patients with HCM.

Adult↗
PubMed1996

Geometric mismatch of the aortic and pulmonary roots causes aortic insufficiency after the Ross procedure.

BACKGROUND: Geometric mismatch between the two semilunar valves can cause aortic insufficiency after the Ross procedure. Thus, whenever the aortic root is larger than the pulmonary root, surgical reduction of the aortic anulus or of the sinotubular junction (or both) to match the diameters of the pulmonary root is necessary to prevent late malfunction of the pulmonary autograft. METHODS: The Ross procedure was performed in 81 patients during the past 5 years. The diameters of the aortic and pulmonary roots were measured in 77 patients. Reduction of the aortic anulus and of the sinotubular junction was necessary in 27 patients, reduction of the aortic anulus alone in 12, and reduction of the sinotubular junction alone in 10. The pulmonary autograft was implanted in the subcoronary position in the aortic root in two patients, as a complete root replacement in 58, and as an inclusion root in 21. RESULTS: There was one operative death, caused by myocardial infarction. Aortic insufficiency developed in one patient who did not have measurement and reduction of the aortic anulus, and aortic root replacement was necessary 2 weeks later. Patients have been followed up from 2 to 64 months (mean 15 months). Two patients have required late reoperations: one because of pulmonary artery stenosis and the other because of a false aneurysm between the autograft and the mitral valve. The most recent Doppler echocardiographic study shows that 90% of the patients have only trace or no aortic insufficiency, and 10% have mild aortic insufficiency. CONCLUSION: This experience suggests that adjustment of the diameter of the aortic anulus or of the sinotubular junction of the aorta may be important to prevent aortic insufficiency after the Ross procedure.

Adolescent↗
PubMed1995

Hypertrophic cardiomyopathy. Clinical spectrum and treatment.

HCM is a heterogeneous disease genotypically, phenotypically, pathophysiologically, clinically, and therapeutically. In decisions on the management of these patients, it is important to recognize this heterogeneity and to direct therapy at the predominant abnormalities.

Adolescent↗
PubMed1995

Angiotensin-I converting enzyme genotypes and left ventricular hypertrophy in patients with hypertrophic cardiomyopathy.

BACKGROUND: The variability of the phenotypic expression of left ventricular hypertrophy (LVH) in patients with hypertrophic cardiomyopathy (HCM) indicates a potential role for additional modifying genes. Variants of angiotensin-I converting enzyme (ACE) gene have been implicated in cardiac hypertrophy. To assess whether ACE genotypes influence the phenotypic expression of hypertrophy, we determined the left ventricular mass index (LVMI) and extent of hypertrophy in 183 patients with HCM. METHODS AND RESULTS: LVMI was derived by the area-length method using two-dimensional echocardiograms. Extent of LVH was determined by a point score method (1 to 10 points). DNA was extracted from blood, and ACE genotyping was performed by polymerase chain reaction (PCR) with an established protocol. Amplification of DNA in the region of polymorphism by PCR of alleles I and D showed 490- and 190-bp products, respectively. ACE genotypes DD, ID, and II were present in 60, 90, and 33 patients with HCM, respectively. In genetically independent patients (n = 108), the mean LVMI (g/m2) was 148 +/- 35.3 in those with DD (n = 35) and 134.2 +/- 33.3 in those with ID and II (n = 73) genotypes (P = .046). LVH score was 6.69 +/- 1.71 in patients with DD and 5.55 +/- 2.19 in those with ID and II genotypes (P = .004). Regression analysis showed that ACE genotypes accounted for 3.7% and 6.5% of the variability of LVMI and LVH score (P = .046 and P = .008, respectively). In 26 patients from a single family, LVMI and LVH score were also greater in patients with DD than in those with ID and II genotypes. ACE genotypes accounted for 14.7% and 10.4% of the variability of the LVMI and extent of hypertrophy, respectively. CONCLUSIONS: ACE genotypes influence the phenotypic expression of hypertrophy in HCM.

Adult↗
PubMed1994

Aortic valve replacement with a stentless porcine aortic valve. A six-year experience.

A stentless porcine aortic valve was used for aortic valve replacement in 123 patients from 1987 to 1993. The mean age of 86 men and 37 women was 61 +/- 12 years. Most patients had aortic stenosis; one-third had coronary artery disease and six had mitral valve disease. The stentless valve was secured in the subcoronary position by the same technique used for a freehand aortic valve homograft. The size of valve was based largely on the diameter of the sinotubular junction of the aortic root. The mean valve size was 26.5 mm (range 19 to 29 mm) and 87% were 25 mm or larger. Two operative deaths occurred, one the result of myocardial infarction and the other the result of infective endocarditis. Patients have been followed up from 3 to 77 months, mean 22 months. Three late deaths, none related to the valve, have occurred. The actuarial survival at 6 years was 91% +/- 4%. Four transient cerebral ischemic events have occurred, but two patients had extracranial cerebrovascular disease. One patient had endocarditis late in the postoperative period and required reoperation. All patients had Doppler echocardiographic studies before discharge from the hospital, 3 to 6 months later and annually. Only 15 patients have aortic insufficiency, trivial in 6 and mild in 9. The peak and mean systolic gradients decreased significantly during the first 3 to 6 months after implantation (p < 0.001), and the effective valve areas increased significantly during this time interval (p < 0.001). This improvement in valve hemodynamics is believed to be due to remodeling of the aortic root and regression of left ventricular hypertrophy. The results of aortic valve replacement with this stentless bioprosthesis have been excellent and justify its continued use in older patients.

Adult↗
PubMed1992

Production and reversibility of right ventricular hypertrophy and right heart failure in dogs.

Combined heart-lung transplantation has been used for end-stage primary pulmonary hypertension. Experience with single-lung transplantation for other conditions suggested that associated severe right ventricular dysfunction resulting from increased afterload would recover after placement of a satisfactory lung allograft. Early experience with the application of single-lung transplantation for pulmonary hypertension supports this contention. We devised a reversible canine model of chronic progressive pressure-overloaded right heart failure by pulmonary artery banding to study the echocardiographic, hemodynamic, and pathological reversibility of the failing right heart. Clinical right heart failure was defined as the development of ascites and pleural effusions. Right heart failure developed in 23 dogs 67 to 348 days after banding, and they were divided into two groups to determine its early and long-term effects. Group 1 dogs (n = 11) were either sacrificed immediately after the onset of right heart failure (n = 5) or unbanded (n = 6); group 2 dogs (n = 12) were maintained in right heart failure for 3 months and then either sacrificed (n = 6) or unbanded. Unbanded dogs in both groups were observed for 4 additional months before sacrifice. A control group of 6 normal dogs was sacrificed for pathological comparisons. After unbanding, the right ventricular systolic pressure fell from 97 +/- 17 mm Hg (group 1) and 88 +/- 31 mm Hg (group 2) to 44 +/- 11 mm Hg and 47 +/- 13 mm Hg, respectively. Despite this persistent gradient across the pulmonary artery, echocardiographic and hemodynamic measures of right ventricular function returned to normal, albeit more slowly in the group 2 dogs.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

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 less than 0.00001] and 20 +/- 2 vs. 15 +/- 3 mm in the control group [p less than 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.

Adult↗
PubMed1992

Aortic valve replacement with the Toronto SPV bioprosthesis.

The Toronto SPV is a Dacron covered stentless porcine aortic prosthesis used for aortic valve replacement (AVR). We implanted this valve in 53 patients with a mean age of 58 years. The predominant valve lesion was aortic stenosis in 39 patients, insufficiency in 13 and a failed bioprosthesis in one. Six patients also had mitral valve disease and 18 had coronary artery disease. There was one operative death. Patients have been followed for four to 58 months, mean 27 months. There have been two late deaths but neither one was valve related. The actuarial survival at four years was 92% +/- 5%. Two patients required reoperation for reasons other than failure of the stentless aortic valve. There have been no thromboembolic complications. No patient had had infective endocarditis. Doppler echocardiographic assessment of the stentless valve revealed excellent effective valve areas and low transvalvular gradients. A few patients developed mild aortic insufficiency after implantation of the valve, but this problem has been practically eradicated by correct sizing of the prosthesis. AVR with the Toronto SPV provides excellent functional and hemodynamic results. This bioprosthesis seems to be associated with an extremely low rate of valve related complications. These findings justify its continued use, but further follow up is needed to determine its durability.

Adult↗
PubMed1992

Surgical treatment of ventricular tachycardia by balloon electric shock ablation. Potential effects on the mitral valve apparatus.

We have previously described a new surgical technique for control of arrhythmogenic foci in patients with recurrent ventricular tachycardia that we call balloon electric shock ablation. With this method sequential shocks are delivered to a grid of electrodes on a balloon that can be introduced across the mitral valve into the intact ventricle. A series of experiments was undertaken to investigate possible deleterious effects of balloon electric shock ablation when shocks are delivered directly to the mitral valve apparatus. In six animals shocks totaling 1200 joules were given through a closely spaced electrode grid applied to the area of the mitral valve. Nine to 12 weeks later, left ventricular and mitral valve function were assessed. Balloon electric shock ablation in the basilar portion of the ventricle was associated with decreased myocardial performance, as evidenced by ejection phase indices. In five of six animals balloon ablation led to minor thickening of the valve leaflets and chordal attachments plus necrosis of adjacent myocardium, including papillary muscles. In these animals there was no significant dysfunction of the valve observed. In the remaining animal, however, ablation was centered on the posterior papillary muscle and resulted not only in necrosis of the base of the papillary muscle but also in full-thickness scarring and thinning of the adjacent left ventricular wall. In this dog, mitral regurgitation was seen on long-term follow-up. We conclude that when balloon electric shock ablation is used to destroy a localized area of myocardium in the basilar portion of the intact ventricle, the procedure results in decreased myocardial performance. When shocks were directly applied to the mitral valve apparatus in five of six animals, ablation did not result in significant negative effects on the structure and function of the valve. In the sixth dog, however, shock delivery resulted in transmural necrosis and thinning at the site of papillary muscle insertion and was associated with severe mitral regurgitation with volume loading. Therefore caution should be used when considering clinical application of this technique if the area to be ablated is in the basal portion of the heart.

Animals↗
PubMed1991

Transoesophageal echocardiogram may fail to diagnose perioperative myocardial infarction.

We report a case in which a 55-yr-old man undergoing aortocoronary bypass was monitored with electrocardiogram and transoesophageal echocardiogram. Intraoperative electrocardiogram and simultaneous ECG recordings using the Holter monitor showed an ST elevation of greater than 2 mm and new Q wave formation in leads AVF and V5 during skin closure. However, the transoesophageal echocardiogram showed no wall motion abnormalities. No significant haemodynamic abnormalities were observed during the period of intraoperative ECG changes. He was treated with nitroglycerin infusion. Confirmation of a perioperative myocardial infarct was documented by postoperative 12-lead ECG and CPK-MB. A post-operative transthoracic echocardiogram showed a hypokinetic left ventricle with an anteroapical infarct. Thus transoesophageal echocardiography failed to detect an apical wall motion abnormality when the probe was placed at the midpapillary level. This limitation can be overcome by periodically obtaining apical views or by using probes with more than one imaging plane.

Aorta↗
PubMed1991

Plasma atrial natriuretic factor concentrations in a canine model of right heart pressure overload.

Two studies were carried out in order to evaluate the plasma atrial natriuretic factor (ANF) concentrations, as well as hemodynamic and renal profiles in a chronic canine model of right heart pressure overload induced by pulmonary artery (PA) banding. In study I (n = 6), the animals were submitted to a gradual increase in pressure to clarify whether an increase in pressure or atrial distension was the main stimulus to ANF secretion. In study II (n = 6), right heart pressure overload was produced more rapidly, resulting in fluid retention and weight gain, thereby completing the model of right heart failure, and allowing an evaluation of the mechanisms involved in ANF resistance. In study I there were significant increases in right atrial pressure over baseline at 20 weeks, ANF levels at 24 weeks and right atrial area at 28 weeks following PA banding. In study II right heart pressures and ANF levels were higher than baseline at 12 weeks (p less than 0.0001), and fluid retention developed between 12-24 weeks in all dogs. The results suggest that increased right heart pressure, rather than atrial size, is a primary stimulus to ANF secretion in chronic right heart pressure overload. Despite the increases in right atrial pressure, clinical fluid retention occurred only with elevations of renin and aldosterone.

Aldosterone↗