Microstructural alterations owing to handling of bovine pericardium to manufacture bioprosthetic heart valves: A potential risk for cusp dehiscence.

INTRODUCTION: Cross-linking and anti-calcification of prosthetic heart valves have been continuously improved to prevent degeneration and calcification. However, non-calcific structural deteriorations such as cuspal dehiscences along the stent still require further analysis. MATERIAL AND METHOD: Based upon the previous analysis of an explanted valve after 7 years, a fresh commercial aortic valve was embedded in poly(methyl methacrylate) (PMMA) and cut into slices to ensure the detailed observation of the assembly and material structures. A pericardial patch embossed to provide the adequate shape of the cusps was investigated after paraffin embedding and appropriate staining. The microstructural damages that occurred during manufacturing process were identified and evaluated by light microscopy, polarized microscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). RESULTS: The wavy collagen bundles, the key structure of the pericardium patch, were damaged to a great extent at suture sites along the stent and in the compressed areas around the stent post. The fixation of the embossed pericardium patch along the plots of the stent aggravated the microstructural modifications. The damages mainly appeared as the elimination of collagen bundle waviness and delamination between the bundles. CONCLUSION: Considering the modes of failure of the explant, the damages to the collagen bundles may identify the vulnerable sites that play an important role in the cusp dehiscence of heart valve implants. Such information is important to the manufacturers. Recommendations to prevent in vivo cusp dehiscence can therefore be formulated.

Estimation of the ejection fraction in patients with myocardial infarction obtained from the combined index of systolic and diastolic left ventricular function: a new method.

UNLABELLED: The index of myocardial performance combining systolic and diastolic time intervals (Index) is a useful method, already explained in past studies, that offers new values that have not been widely known among clinical cardiologists. The aim of this study is to obtain from this Index a measurement of the ejection fraction (EF), which is a very well-known value. The study involved 97 patients with myocardial infarction, 55 of whom were studied retrospectively (group A, aged 46-62 years, 50 men) to obtain and test the formula EF = 60 - (34 x Index). The second group (group B, aged 47-63 years, 40 men) included 42 patients who were evaluated prospectively. The EF obtained was compared with that reached through the use of radionuclide angiography (EF-RNA). The Index was obtained through the use of the formula (a - b)/b, where a is the interval between cessation and onset of the mitral inflow, and b is the ejection time. In group A the EF obtained by the Index (EF-Index) was 37.5% +/-.8%, and the EF-RNA was 37.7% +/- 11% (r = 0.76). In group B the EF-Index was 41.6% +/- 7%, and the EF-RNA was 41.2% +/- 10% (r = 0. 75). CONCLUSION: Through the new formula described here it is possible to obtain a reliable measurement of the EF in patients with myocardial infarction, a well-known and extremely useful value, especially for those patients with poor acoustic windows.

Ambulatory blood pressure monitoring and diastolic left ventricular abnormalities in established and borderline hypertension

In order to evaluate left ventricular diastolic function by means of Doppler echocardiography in borderline and established hypertension, identified by office and ABPM, compared with normotensives, 54 subjects: 15 normotensives, 11 borderlines and 28 nontreated mild to moderate essential hypertensives were studied. Age and weight were similar among groups. Established hypertensives showed higher left ventricular mass index (p < 0.05), peak velocity of late left ventricular filling (peak A; p < 0.01), ratio peak A/peak velocity of early ventricular filling, peak E (p < 0.01), velocity time integral of systolic atrial volume (p < 0.001), deceleration half time of peak early diastolic inflow velocity (p < 0.05), left ventricular isovolumic relaxation period (IRP; p < 0.01) than normotensives and lower Doppler indexes of early diastolic left ventricular filling (p < 0.01), peak filling rat normalized to mitral stroke volume (PFRn; p < 0.01) than normotensives. Although borderline hypertensives showed intermediate LVM and Doppler indexes between hypertensives and normotensives only IRP (p < 0.05) and PFRn (p < 0.05) were significant different to normotensives. In conclusion, established hypertension leads to abnormalities in left ventricular diastolic function which can be detected by Doppler echocardiography. In borderline hypertension, the left ventricular diastolic abnormalities are predominantly related to the active process of early diastole. Therefore, these indexes may be early markers of left ventricular dysfunction in hypertension.

Ambulatory blood pressure monitoring and diastolic left ventricular abnormalities in established and borderline hypertension.

In order to evaluate left ventricular diastolic function by means of Doppler echocardiography in borderline and established hypertension, identified by office and ABPM, compared with normotensives, 54 subjects: 15 normotensives, 11 borderlines and 28 nontreated mild to moderate essential hypertensives were studied. Age and weight were similar among groups. Established hypertensives showed higher left ventricular mass index (p < 0.05), peak velocity of late left ventricular filling (peak A; p < 0.01), ratio peak A/peak velocity of early ventricular filling, peak E (p < 0.01), velocity time integral of systolic atrial volume (p < 0.001), deceleration half time of peak early diastolic inflow velocity (p < 0.05), left ventricular isovolumic relaxation period (IRP; p < 0.01) than normotensives and lower Doppler indexes of early diastolic left ventricular filling (p < 0.01), peak filling rat normalized to mitral stroke volume (PFRn; p < 0.01) than normotensives. Although borderline hypertensives showed intermediate LVM and Doppler indexes between hypertensives and normotensives only IRP (p < 0.05) and PFRn (p < 0.05) were significant different to normotensives. In conclusion, established hypertension leads to abnormalities in left ventricular diastolic function which can be detected by Doppler echocardiography. In borderline hypertension, the left ventricular diastolic abnormalities are predominantly related to the active process of early diastole. Therefore, these indexes may be early markers of left ventricular dysfunction in hypertension.

The value of the echo-Doppler in cardiomyoplasty procedures.

UNLABELLED: Echo-Doppler determinations were performed in patients submitted to cardiomyoplasty procedure using the latissimus dorsi muscle graft (LDMG). In four patients who had 1 year of follow-up or more the left ventricular internal dimension in diastole (LVIDd), left ventricular internal dimension in systole (LVIDs), septal-E point separation (E-septum), distance of the mitral valve (E-E'), maximal aortic cuspid separation (MACS) and left atrium dimension (LA) were determined by two-dimensional echocardiogram. With a pulsed Doppler in the aortic root the following parameters were obtained: aortic peak flow (AoPF), velocity time integral (VTI), and ejection period (EP). With the stimulator on, the determinations were done using a ventricle muscle (VM) delay of 25, 75, and 250 msec. RESULTS: No significant differences were observed by Echo determinations between the stimulator off and on. With the supporting contraction of the LDMG the best hemodynamic performance was obtained when the VM delay ranged between 75 and 250 msec. Values with the stimulator off and on were as follows: AoPF: 90.8 +/- 8 cm/sec and 104.5 +/- 9 cm/sec; VTI: 14.8 +/- 2 cm and 19.2 +/- 2 cm; EP: 230 +/- 10 msec and 245 +/- 20 msec. A decrease in the systolic pressure of the pulmonary artery and a decreased functional regurgitation of the mitral and tricuspid valve were observed in the follow-up determinations. All patients showed restricted mitral flows that remained unchanged during the follow-up. CONCLUSIONS: In this group of patients the echo-Doppler showed an improvement of the systolic function of the left ventricle when it is supported by the LDMG.(ABSTRACT TRUNCATED AT 250 WORDS)

Long-term evaluation of cilazapril in severe hypertension. Assessment of left ventricular and renal function.

The effect of cilazapril as monotherapy or in combination with hydrochlorothiazide was assessed in 30 severely hypertensive patients, 23 men and seven women, aged 38 to 68 years, with sitting diastolic blood pressure of more than 115 mmHg. Fifteen patients had left ventricular hypertrophy documented by two-dimensional echo-cardiography. Sitting systolic blood pressure was reduced from 175.8 +/- 2.0 to 143.3 +/- 3.0 mmHg within 25 days of therapy (p less than 0.0001); sitting diastolic blood pressure decreased in the same period from 117.0 +/- 1.0 to 87.8 +/- 2.0 mmHg (p less than 0.0001), whereas heart rate remained unchanged. In 19 patients treated for an average of 48 weeks the therapeutic response was maintained during the long-term period. The mean effective dose was cilazapril 10 mg plus hydrochlorothiazide 12.5 to 25 mg in 90 percent of the patients. Left ventricular mass decreased from 357 +/- 17 to 314 +/- 22 g (nine patients; p less than 0.005) and a correlation (Spearman r = 0.57, p less than 0.01) was found between left ventricular mass and sitting systolic blood pressure before and during treatment. Deceleration half time of peak early diastolic inflow velocity decreased significantly from 128 +/- 9 to 108 +/- 7 msec (p less than 0.05). Glomerular filtration rate and renal blood flow remained within normal limits, whereas renal vascular resistance decreased from 0.16 +/- 0.0 to 0.10 +/- 0.0 resistance units (10 patients; p less than 0.01). Cilazapril in combination with hydrochlorothiazide was effective in the treatment of severe hypertension. Left ventricular hypertrophy regression influenced favorably left ventricular diastolic function in some patients, whereas renal hemodynamics were generally not affected by the therapy.

[Evaluation of the anti-arrhythmia effect of intravenous flecainide in supraventricular tachyarrhythmias]. / Valoración antiarrítmica de la flecainida endovenosa en las taquiarritmias supraventriculares.

We studied the effects of intravenous flecainide acetate, given as a single dose of 2 mg/kg in no less than 15 minutes, on 31 patients with supraventricular tachyarrhythmias. Fourteen (87%) of the 16 patients with paroxysmal atrial fibrillation converted to sinus node rhythm. All 7 (100%) of the patients with paroxysmal supraventricular tachycardia converted to sinus node rhythm. Five (60%) of the 8 patients with paroxysmal atrial flutter converted to sinus node rhythm. The average time of conversion, after completion of drug administration, was 15 +/- 20 minutes. The QRS was prolonged an average of 82 to 91 milliseconds; in those cases who converted, the PR interval duration was 180 milliseconds average; QT was prolonged an average of 425-450 milliseconds. There were no changes in the JT interval, and we observed no hemodynamic untoward effects.