Mathematical and Ex Vivo Thermal Modeling for Renal Tumor Radiofrequency Ablation with Pyeloperfusion.

BACKGROUND AND PURPOSE: Radiofrequency ablation (RFA) is an effective technique for the treatment of patients with small renal tumors, although it is often limited to tumors at least 2 cm from the renal pelvis or ureter. Retrograde pyeloperfusion (PPF) of the pelvis with cold saline during RFA may protect the pelvis and ureter. We designed a mathematical and ex vivo model of RFA to investigate the effects of PPF. METHODS: Our theoretical model uses heat transfer principles simplifying the RFA probe to a heat-emitting cylinder within a material. In the ex vivo model, an RFA probe was placed 18 mm from the pelvis in porcine kidneys and with temperature probes on either side of the RFA probe. Control trials with no PPF were compared with either cold saline (2°C), warm saline (38°C), or antifreeze (-20°C) pumped into the renal calix at a rate of 60 mL/min. Ablated volumes were measured and confirmed histologically. RESULTS: The average steady state temperatures at each probe were highest with no PPF, followed by warm saline, cold saline, then antifreeze. Compared with no PPF, temperatures were significantly (P<0.05) colder with warm saline (-8.4°C), cold saline (-18°C), and significantly colder at the calix (warm -14°C, cold -27°C). While RFA output a constant voltage, significantly lower resistances in warm (171Ω) and cold (124Ω) PPF vs no PPF (363Ω) translated to significantly greater power outputs in warm (40 W) and cold (42 W) vs no PPF (14 W). The ablated volumes were significantly higher in warm saline (2.3 cm(3)) vs cold saline (0.84 cm(3)) and no PPF (1.1 cm(3)). Mathematical modeling produced a predictive temperature curve with R2=0.44. CONCLUSION: PPF lowers temperatures throughout the entire kidney during RFA, most notably near the collecting system and is dependent on the temperature of the liquid used. In addition, PPF may cause less charring of the tissue around the probe resulting in lower resistance and higher power outputs.

Urology Patients and the Internet: Socioeconomic Status and Language Skills Significantly Impact Use.

INTRODUCTION: Patient Internet use and resources are likely multifactorial. We assess how socioeconomic factors and language skills affect Internet use by patients. METHODS: We prospectively surveyed 116 patients with a bilingual questionnaire before they underwent urological surgery from July to September 2013. We obtained institutional review board approval for this study. Patients were surveyed for demographic data, English abilities, Internet use, anxiety level and understanding of the surgery. RESULTS: Patients with low English abilities were significantly more likely to have lower incomes and education (p <0.05). In addition, patients with low English abilities were significantly more likely neither to have Internet access nor to have used it to research their surgery. On multivariate analysis those with low confidence in English were 2.8 times more likely not to have used the Internet to research their surgery when controlling for age. Increased age remained statistically associated with a lower likelihood of using the Internet even when controlling for all demographic data. Lastly, patients with low confidence in English were significantly less likely to report increased anxiety before surgery (OR 0.147) when controlling for all demographic data including ethnicity. CONCLUSIONS: In our community those patients with low confidence in their English abilities are less likely to have access to, and use, the Internet before undergoing surgery. Older patients also use the Internet less often. Urologists should be aware of this potential language and age gap. Those with low English skills should likely be provided with additional counseling.

Long-term oncologic outcomes following radiofrequency ablation with real-time temperature monitoring for T1a renal cell cancer.

OBJECTIVE: Few studies report long-term follow-up of renal cancer treated by radiofrequency ablation (RFA), thus limiting the comparison of this modality to well-established long-term follow-up series of surgically resected renal masses. Herein, we report long-term oncologic outcomes of renal cancer treated with RFA in a single institution. METHODS AND MATERIALS: We retrospectively reviewed patients treated between November 2001 and October 2012 with laparoscopic-guided or computed tomography-guided RFA. All treatments were performed with real-time thermometry ensuring target ablation temperature (>60°C) was adequately reached. Only patients with biopsy-confirmed T1a-category cancer and a follow-up period>48 months were included in our analysis. Follow-up included office visits, laboratory work, and periodic contrast-enhanced imaging. Survival was calculated using the Kaplan-Meier analysis. Overall complications were reported using the Clavien-Dindo scale. RESULTS: Of 434 RFA cases, 53 treatments in 50 patients met the inclusion criteria. Of these, 29 were treated with computed tomography-guided RFA and 24 with laparoscopic-guided RFA. The mean follow-up interval was 65.6 months (48.5-120.2), and the mean renal mass size was 2.3 cm (0.3-4.0). There were 4 (7.5%) local recurrences and 1 case of distant metastases with no local recurrence. The 5-year overall survival was 98%, cancer-specific survival was 100%, and recurrence-free survival was 92.5%. The complication rate was 26.4%, which included 71% of Clavien-Dindo grade I and 29% of grade II. Mean estimated glomerular filtration rate preoperatively and at the most recent follow-up visit was 77 and 66 ml/min, respectively. CONCLUSIONS: When performed on selected patients, while monitoring real-time temperatures to ensure adequate treatment end points, RFA offers favorable long-term oncologic outcomes approaching those reported for partial nephrectomy.

Some observations on the interdigitation of advances in medical science and mathematics.

The immense advancement of our understanding of disease processes has not been a uniform progression related to the passage of time. Advances have been made in "lurches" and "catches" since the advent of the written word. There has been a remarkable interdependency between such advances in medicine and advances in mathematics that has proved beneficial to both. This work explores some of these critical relationships and documents how the individuals involved contributed to advances in each.

Broken heart syndrome: a risk of teenage rhinoplasty.

"Broken heart" syndrome is a rare phenomenon characterized by transient ballooning of the left ventricle and chronic heart failure, usually presenting in postmenopausal women. It is formally known as acute stress-induced cardiomyopathy and, although described in the cardiology literature, it has not been previously described in plastic surgery patients. It is thought to occur secondary to increased catecholamine levels. This case report outlines two instances of the syndrome occurring in teenage girls undergoing cosmetic rhinoplasty.

Spontaneous coronary artery dissection.

Spontaneous coronary artery dissection (SCAD) is a rare and potentially deadly disease without a clear and universal treatment. Medical as well as mechanical interventions, including percutaneous and coronary bypass surgery, have been used. We present two dissimilar cases of SCAD that required markedly different treatments reflecting the variety in clinical presentation and outcome. A brief review of the literature is included.