Biomedical subjects

Ganapathy K Subramaniam

Publications and source records attributed to Ganapathy K Subramaniam.

9 recordsLinked to original sources

PubMed2006

Intra-aortic balloon counterpulsation in a patient with the failing Fontan circulation.

We report a 23-year-old patient undergoing functionally univentricular repair who developed cardiac failure due primarily to systemic ventricular dysfunction. The failing Fontan circulation was successfully re-established using intra-aortic balloon counterpulsation. Aortic counterpulsation facilitates recovery of systemic ventricular function, and appears to be a reasonable alternative in select instances of cardiac failure in patients with the Fontan circulation.

Adult↗

PubMed2006

Serial radionuclide angiographic assessment of left ventricular ejection fraction and regional wall motion after mitral valve replacement in patients with rheumatic disease.

BACKGROUND: This study was designed to prospectively investigate the effects of total or partial chordal-sparing and chordal-nonsparing mitral valve replacement (MVR) procedures on regional and global ventricular function in a rheumatic population using sequential multiple-gated acquisition scan. METHODS: One hundred five consecutive patients undergoing different techniques of chordal preservation procedures during MVR are included in this prospective study. Fifteen patients had complete excision of the chordopapillary apparatus (group 1), 34 had total chordal preservation (group 2), and 56 had preservation of the posterior chordopapillary apparatus (group 3). Radionuclide-derived left ventricular ejection fraction (LVEF) and regional wall motion (RWM) studies on 99 survivors were performed preoperatively, at discharge, at 1 year, and at 2 years. RESULTS: At discharge, there was a decline in LVEF in all the 3 groups. Statistically significant improvement in ejection fraction occurred in the chordal preservation groups (2 and 3) (P < .05) as compared with the nonchordal group immediately and late postoperatively. Only the total chordal group (2) demonstrated complete recovery of LVEF by 2 years postoperatively. Significant and persistent RWM abnormalities were noted in both the nonchordal and posterior chordal groups. CONCLUSIONS: We conclude that complete retention of the chordopapillary apparatus during MVR provides superior results compared with nonchordal and partial chordal preservation in terms of preservation of LVEF and reduced incidence of abnormal postoperative RWM.

Adult↗

PubMed2006

Pericardiectomy for constrictive pericarditis: a clinical, echocardiographic, and hemodynamic evaluation of two surgical techniques.

BACKGROUND: This study was designed to compare the outcomes after total versus partial pericardiectomy clinically, echocardiographically, and hemodynamically. METHODS: Three hundred ninety-five patients undergoing pericardiectomy for constrictive pericarditis between January 1985 and December 2004 were studied. Age was 10 months to 71 years (mean, 25.1 +/- 13.4 years). Three hundred thirty-eight patients (85.6%) underwent total pericardiectomy (group I), and 57 patients (14.4%) underwent partial pericardiectomy (group II). RESULTS: Operative and late mortality rates were 7.6% and 4.9%, respectively. Preoperative high right atrial pressure, hyperbilirubinemia, renal dysfunction, atrial fibrillation, pericardial calcification, thoracotomy approach, and partial pericardiectomy were significant risk factors for death. The risk of death was 4.5 times higher (95% confidence interval: 2.05 to 9.75) in patients undergoing partial pericardiectomy. At a mean follow-up of 17.9 +/- 0.3 years (95% confidence interval: 17.3 to 18.6), actuarial survival was 83.8% +/- 0.04% in group I and 73.9% +/- 0.06% in group II (p = 0.004). At their last follow-up, 96.3% survivors of group I and 79.1% survivors of group II were in New York Heart Association class I/II (p < 0.001). CONCLUSIONS: Total pericardiectomy is associated with lower perioperative and late mortality, and confers significant long-term advantage by providing superior hemodynamics that appear to be independent of the etiology of constrictive pericarditis.

Adolescent↗

PubMed2005

Specific issues after extracardiac fontan operation: ventricular function, growth potential, arrhythmia, and thromboembolism.

BACKGROUND: The purpose of this study was to define the prevalence of specific sequelae after extracardiac Fontan operation. METHODS: Sixty-five consecutive patients undergoing extracardiac Fontan operation were studied for mortality, Fontan failure, systemic ventricular function, supraventricular arrhythmias, thromboembolism, and growth potential. Age was 3 to 31 years (mean +/- standard deviation, 9.4 +/- 1.8; median, 7 years). The conduits were constructed of polytetrafluoroethylene (n = 50), and "viable" in situ pericardium (n = 15). The patients underwent serial echocardiogram, dynamic radionuclide studies, and cardiac catheterization. RESULTS: Operative mortality was 3%, and the incidence of conduit thrombosis was 4.6%. There was paradoxic filling of the right lung after femoral injection of the radiotracer in all cases of conduit obstruction. Perioperative and late postoperative supraventricular arrhythmias were observed in 9.2% and 4.7% of patients, respectively. Risk factors for supraventricular arrhythmias included systemic ventricular dysfunction (p = 0.000), heterotaxy syndrome (p = 0.008), systemic venous anomalies (p = 0.015), and previous bidirectional Glenn operation (p = 0.017). At a mean follow-up of 77 +/- 2 months (range, 8 to 79 months), there were no late deaths (actuarial survival at 79 months, 96.9% +/- 0.02%). Serial echocardiograms demonstrated evidence of growth of the viable tunnels. Postoperatively, there was transient depression of ejection fraction in all patients (p = 0.000). CONCLUSIONS: Supraventricular arrhythmias after extracardiac Fontan are more common in patients with heterotaxy syndrome, bilateral superior venae cavae, systemic ventricular dysfunction, and those undergoing completion Fontan operation. The viable tunnel may emerge as an optimal alternative by virtue of reduction of supraventricular arrhythmias, elimination of the need for anticoagulation, and addressing the issue of growth potential in selected patients.

Adolescent↗

PubMed2005

One and one-half ventricle repair: results and concerns.

BACKGROUND: The study was designed to assess the long-term results of one and one-half ventricular repair on systemic and pulmonary circulation, right ventricular growth and function, and the prevalence of arrhythmias. METHODS: Eighty-four patients undergoing one and one-half ventricular repair between January 1990 and December 2003 were studied. Age was 4 to 504 months (mean, 47.9 +/- 57.3 months). Sixty-nine survivors underwent serial echocardiography, radionuclide studies, cardiac magnetic resonance imaging, and cardiac catheterization. RESULTS: Operative and late mortality were 10.7% and 8%, respectively. Perioperative and postoperative supraventricular arrhythmias were observed in 14.3% and 15.9% of patients, respectively. Risk factors for supraventricular arrhythmias included systemic ventricular dysfunction, heterotaxy syndrome, and Ebstein's anomaly. Mean late postoperative superior vena caval pressure was 14.2 +/- 1.52 mm Hg and right atrial pressure was 6.6 +/- 0.74 mm Hg. At a median follow-up of 87 months, actuarial survival was 81.9% +/- 0.04%, and 89.8% were in New York Heart Association class I or II. Serial cine-magnetic resonance imaging demonstrated significant growth of tricuspid valve and right ventricular cavity in 45% of patients. CONCLUSIONS: One and one-half ventricular repair can be performed with an acceptable risk. The operation maintains a low pressure in the inferior vena caval tributaries, and reverses the Fontan paradox. Patients with tripartite right ventricles demonstrated a tendency toward enlargement of the pulmonary ventricular chamber commensurable with somatic growth.

Adolescent↗

PubMed2004

Postoperative assessment of the univentricular repair by dynamic radionuclide studies.

BACKGROUND: The purpose of this investigation was to determine the role of radionuclide studies in evaluating postoperative Fontan hemodynamics and to quantify its diagnostic accuracy. METHODS: One hundred five patients (105), aged 11 months to 35 years old, who had undergone univentricular repair, underwent first-pass and multigated acquisition scan 1 month to 10 years after univentricular repair. Forty-five patients with evidence of Fontan failure underwent radionuclide studies using Technetium-99 m as well as cardiac catheterization (group 1). The remaining sixty randomly selected patients with excellent functional status received radionuclide studies alone (group 2). The receiver operating characteristic curve analysis was done to quantify the diagnostic accuracy of the first-pass study. RESULTS: There was paradoxical filling of the right lung after femoral injection in all cases of tunnel or conduit obstruction. A first-pass transit time of 16 to 25 seconds (mean +/- standard deviation [SD] = 18.82 +/- 2.69) was always associated with Fontan failure and high right atrial pressure (range = 20 to 24 mm Hg, mean +/- SD = 22.02 +/- 1.58). A first-pass transit time of 16 seconds was associated with a sensitivity of 100% and a specificity of 93.33%. The predictive accuracy of a positive or negative result was 91.8% and 100% respectively. The area measured under the receiver operating characteristic curve indicates that 99.41% (SE +/- 0.0035) of the time, the value of first-pass time is higher for the Fontan failure group (group 1) compared to the normal group (group 2; p = 0.000). CONCLUSIONS: Our data indicate that Fontan circuit can be reliably evaluated for both anatomic and functional flaws by radionuclide studies; radionuclide first-pass time may be used to predict the chances of Fontan failure postoperatively as well as its presence; and in the presence of atrial fibrillation with fast ventricular rate, analysis using first-pass radionuclide may be impossible and gated equilibrium radionuclide angiocardiography may be the preferred method. Inspection of the systemic ventricular time-activity curve is of crucial importance in this regard.

Adolescent↗

PubMed2004

Histopathology and morphometry of radial artery conduits: basic study and clinical application.

BACKGROUND: The purpose of this study was to determine the pathohistology, morphometry, and risk factors for the development of intimal hyperplasia, calcification, and arteriosclerosis in the radial artery and to compare the morphometry of the distal and proximal radial arteries. METHODS: A total of 190 proximal and distal radial artery specimens obtained from patients who underwent myocardial revascularization were exposed to histopathologic and morphometric analysis. The severity of disease was evaluated on the basis of the percentage of luminal narrowing, intimal thickness index, and intima-to-media ratio. RESULTS: Sixty-two proximal (32.6%) and 22 distal (11.5%) radial artery segments were indicated as histologically normal. Morphometric analysis (Z test) revealed a lesser degree of intimal hyperplasia and luminal narrowing in the proximal segments compared with the distal segments (p < 0.001). The incidence of intimal hyperplasia, medial calcification, and arteriosclerosis in the distal radial arteries was 76.3%, 6.3%, and 5.78%, respectively. Using multivariate logistic regression, we have identified three significant predictors for intimal hyperplasia. Expressed as an odds ratio with a 95% confidence interval, these included (i) age greater than 50 years (1.052; 1.000-1.106, p = 0.052), (ii) smoking (14.073; 5.293-37.414, p = 0.000), and (iii) hypertension (2.777; 1.171-6.583, p = 0.020). Factors associated with an increased likelihood of medial calcification and arteriosclerosis included a history of smoking, diabetes, hypercholesterolemia, peripheral arterial disease, and chronic renal failure (p < 0.05). CONCLUSIONS: The great majority of radial artery conduits indicate preexisting intimal hyperplasia mostly affecting the distal portion. Therefore in cases of longer diseased segments of radial arteries, the discarded segments should be the distal end. Care should be taken when selecting radial artery as a conduit in myocardial revascularization, particularly in elderly males, diabetics, smokers, hypertensive patients, and in those with associated peripheral vascular disease.

Adult↗

PubMedDate not supplied

Surgical outcome of staged univentricular-type repairs for patients with univentricular physiology and pulmonary hypertension.

BACKGROUND: There is no consensus about the most appropriate limits of pulmonary artery pressure and vascular resistance in case of patients undergoing univentricular or one and one-half ventricular repair. This study was conducted to analyze the mortality and morbidity of a heterogenous group of patients with a functionally univentricular heart and pulmonary artery hypertension, undergoing pulmonary artery banding followed by univentricular-type repairs. METHODS AND RESULTS: Out of 254 patients undergoing pulmonary artery banding for a functionally univentricular heart with increased pulmonary blood flow, 148 patients underwent definitive second stage surgery. Post-band hemodynamic evaluation revealed persistently high pulmonary artery pressure (> 18 mmHg), and pulmonary vascular resistance (>2.0 Woods units/m2) in 78.3% patients. Sixteen patients with moderate right ventricular hypoplasia were given a one and one-half ventricle repair (Group I), 82 patients a bidirectional Glenn connection (Group II), and 50 patients a fenestrated total cavopulmonary connection (Group III). The overall mortality following second stage surgery for the high pulmonary artery pressure group (n=116) was 30.17%, while none of the low pulmonary artery pressure group died (p=0.0009). Pulmonary hypertensive crises and/or systemic desaturation were the main causes of death at second stage repair. All mortality occurred in patients with mean pulmonary artery pressure > 18 mmHg and pulmonary vascular resistance > 3.5 Woods units/m2. Survivors from this group had persistent morbidity in the form of superior vena caval syndrome and suboptimal oxygen saturation (70-75%). CONCLUSIONS: It is advisable not to proceed with definitive second stage repair if post-pulmonary artery banding mean pulmonary artery pressure is over 25 mmHg and pulmonary vascular resistance exceeds 4.0 Woods units/m2. These patients may possibly be deemed to have undergone definitive palliation during their pulmonary artery banding.

Cardiac Surgical Procedures↗

PubMedDate not supplied

Congestive heart failure in unoperated tetralogy of Fallot: can hypoxia be a cause?

A 10-year-old boy with tetralogy of Fallot and congestive heart failure underwent a right-sided modified Blalock-Taussig anastomosis because of severe biventricular dysfunction and repeated hypercyanotic spells. Postoperatively, there was improvement in systemic oxygen saturation and myocardial function. We postulate that congestive heart failure occurred because of severe myocardial hypoxia and its elimination resulted in markedly improved cardiac performance.

Blood Vessel Prosthesis Implantation↗